Data dictionary of the Level II aggregated forest soil condition database AFSCDB.LII.2.2
based on
Fleck, S., Cools, N., De Vos, B., Meesenburg, H., Fischer, R. (2016): The Level II aggregated forest soil condition database links soil physicochemical and hydraulic properties with long-term observations of forest condition in Europe
1 Data Dictionary for the Aggregated Forest Soil Condition Database of the Level II, Second Soil Survey (AFSCDB.LII.2.2)
This data dictionary shall provide a direct link to the measurement methods applied for those of the 252 variables in the database that were defined by measurement protocols or code lists. The table below contains all variables in alphabetical order with reference to the database tables they are used in (. Direct links to the different sources of information are offered in its last column. The bibliographic information of the references is given below the table with corresponding numbers. In the case that different versions of a literature source are needed to exactly describe the methods, the number of the source is followed by a minor case letter (1a, 1b, etc.).
Variable Name Description Unit Sources
bdest Estimated bulk density of the kg m-3 4 (SOM) fine earth
bdsample Mean dry soil bulk density of kg m-3 4 (SWR) fine earth of the samples (Cools and De Vos 2010)
bs Base saturation of the horizon % 3 (PFH, SOM) [(exchangeable Ca+Mg+K+Na)/cation exchange capacity * 100]
bulk_density Mean bulk density of fine kg m-3 4 (SOM, SWA) earth
carbonates Carbonate content g kg-1 4 (SOM)
cn C:N ratio: 3 (SOM) [organic_carbon_total] / [n_total]
coarse_fragment_mass Mass of coarse fragments (> 2 g 100g-1 4 (SOM) mm)
coarse_fragment_vol Volume of coarse fragments (> Vol % 4 (SOM) 2 mm)
code_altitude Altitude in 50 metre classes Code 1 (PLS) (from 1 till 51, PCC (2012))
code_country number code for the country Code 1 (LQA, PFH, PLS, PRF, (PCC 2012) SOM, STO, SWA, SWR)
2 code_determination Determination method (see Code 1 (LQA) reference list) code_horizon_coarse_vol Code of volume class of coarse Code 1, 4 (PFH) fragments (stones and gravel with a diameter > 2 mm) code_horizon_discont Number to indicate a Code 1 (PFH) discontinuity in the horizon designation code_horizon_distinct Code of horizon distinction Code 1 (PFH) code_horizon_master Symbol of the master part of Code 1 (PFH) the horizon designation code_horizon_porosity Class of total porosity Code 1, 4 (PFH) code_horizon_subordinat Symbol of the subordinate Code 1 e characteristics of the horizon (PFH) designation code_horizon_texture_cl Horizon textural class (USDA) Code 3, 4, 7 ass (PFH) code_horizon_topo Code of horizon topography Code 1 (PFH) code_humus Code referring to the humus Code 1 (PLS) type (PCC 2012) code_layer The code of the fixed depth Code 1 4 (SOM, SWA, SWR) layer (PCC 2012) code_parameter Code of soil variable Code 1, 4 (LQA) code_parent_material_1 Code for the dominant parent Code 1, 9 (PRF) material of the plot (PCC 2012) code_parent_material_2 Code for a second parent Code 1, 9 (PRF) material (PCC 2012) code_plot code for the plot given by the Code 1 (LQA, PFH, PLS, PRF, country SOM, STO, SWA, SWR) code_pretreatment Digestion/Extraction method Code 1 (LQA) (pretreatment)
3 code_prof Identification code of the Code 1 (PFH, PRF) profile code_roots_coarse Abundance class of coarse Code 1, 4 (PFH) roots code_roots_fine Abundance class of fine roots Code 1, 4 (PFH) code_roots_medium Abundance class of medium Code 1, 4 (PFH) roots code_roots_very_fine Abundance class of very fine Code 1, 4 (PFH) roots code_sieving Sieving/milling method Code 1, 4 (LQA) code_soil_structure Type of the soil structure Code 1 (PFH) code_swprf ID of the most representative Code 1 (SWR) soil water profile for the plot code_texture_class USDA texture class Code 4, 7 (SOM) code_water Code referring to the water Code 1 (PLS) availability for trees (PCC 2012) code_water_level_high Mean highest groundwater Code 1, 4 (PRF) depth (in depth classes) code_water_level_low Mean lowest groundwater Code 1, 4 (PRF) depth (in depth classes) code_water_type Type of water table (9 = no Code 1, 4 (PRF) water table; 1 = perched; 2 = permanent) code_wrb_publication Reference to WRB version Code 1, 2a, 2b, 2c (PRF) (IUSS Working Group WRB 2006, 2007) code_wrb_qualifier_x (x xth qualifier describing the Code 1, 2a, 2b , 2c (see being numbers from 1 to reference soil group code_wrb_publication) 6) (PRF)
4 code_wrb_soil_group World Reference Base, Code 1, 2a, 2b , 2c (see (PRF) Reference Soil Group of the code_wrb_publication) plot code_wrb_specifier_x (x Specifier for the xth qualifier Code 1, 2a, 2b , 2c (see being numbers from 1 to code_wrb_publication) 6) (PRF) colour_dry Dry colour of the soil matrix 1, 10 (PFH) (Munsell soil colour charts) colour_moist Moist colour of the soil matrix 1, 10 (PFH) (Munsell soil colour charts) control_chart_mean Mean of control chart 3, 8 (LQA) control_chart_std Relative standard deviation 3, 8 (LQA) [%] datasource Name of the project under Text (PLS) which countries did the soil sampling date_end end date YYYY-MM- 1 (LQA) DD date_labor_analyses Date of the final (most recent) YYYY-MM- 1 (PFH, SOM, SWA, SWR) laboratory analysis DD date_profile_desc Date of description of the soil YYYY-MM- 1 (PRF) profile DD date_sampling Date of sampling YYYY-MM- 1 (PLS, SWA, SWR) DD date_start start date YYYY-MM- 1 (LQA) DD ddlat Latitude of the plot in decimal degrees Unit conversion from (PLS) degrees, datum = WGS84 latitude ddlong Longitude of the plot in degrees Unit conversion from (PLS) decimal degrees, datum = longitude WGS84 depth_diagnostic_x (x Depth of appearance of xth cm 1 being numbers from 1 to diagnostic horizon, property 10) or material from top of (PRF) mineral soil
5 depthstock Depth to be used for stock cm actual paper (PRF) calculation (max. 1 m) diagnostic_x (x being Code of xth diagnostic horizon, 1, 2a, 2b , 2c (see numbers from 1 to 10) property or material code_wrb_publication) (PRF) esp Exchangeable sodium % 1, 2a, 2b , 2c (see (PFH) percentage of the horizon code_wrb_publication) (expressed as % of CEC) etrs89x Longitude of the plot in m ETRS89-LAEA (PLS) European Terrestrial Reference System 1989 – Lambert Azimuthal Equal Area Projection Coordinate Reference System etrs89y Latitude of the plot in m ETRS89-LAEA (PLS) European Terrestrial Reference System 1989 – Lambert Azimuthal Equal Area Projection Coordinate Reference System
-1 exch_ace Sum of acid cations (Al, Fe, Mn cmol+ kg actual paper (SOM) and Free H+)
-1 exch_acidity Total exchangeable acidity cmol+ kg 4 (SOM)
-1 exch_al Exchangeable Al cmol+ kg 4 (SOM)
-1 exch_bce Sum of basic cations (Ca, K, cmol+ kg actual paper (SOM) Mg, Na)
-1 exch_ca Exchangeable Ca cmol+ kg 4 (SOM)
-1 exch_cec Cation exchange capacity: cmol+ kg actual paper (SOM) Sum of [exch_bce] and 4 [exch_ace]
-1 exch_fe Exchangeable Fe cmol+ kg 4 (SOM)
-1 exch_k Exchangeable K cmol+ kg 4 (SOM)
-1 exch_mg Exchangeable Mg cmol+ kg 4 (SOM)
6 -1 exch_mn Exchangeable Mn cmol+ kg 4 (SOM)
-1 exch_na Exchangeable Na cmol+ kg 4 (SOM) extrac_al Aqua regia extractable Al mg kg-1 4 (SOM) extrac_ca Aqua regia extractable Ca mg kg-1 4 (SOM) extrac_cd Aqua regia extractable Cd mg kg-1 4 (SOM) extrac_cr Aqua regia extractable Cr mg kg-1 4 (SOM) extrac_cu Aqua regia extractable Cu mg kg-1 4 (SOM) extrac_fe Aqua regia extractable Fe mg kg-1 4 (SOM) extrac_hg Aqua regia extractable Hg mg kg-1 4 (SOM) extrac_k Aqua regia extractable K mg kg-1 4 (SOM) extrac_mg Aqua regia extractable Mg mg kg-1 4 (SOM) extrac_mn Aqua regia extractable Mn mg kg-1 4 (SOM) extrac_na Aqua regia extractable Na mg kg-1 4 (SOM) extrac_ni Aqua regia extractable Ni mg kg-1 4 (SOM) extrac_p Aqua regia extractable P mg kg-1 4 (SOM) extrac_pb Aqua regia extractable Pb mg kg-1 4 (SOM) extrac_s Aqua regia extractable S mg kg-1 4 (SOM) extrac_zn Aqua regia extractable Zn mg kg-1 4 (SOM)
7 -1 free_h Free H+ acidity of the layer cmol+ kg 4 (SOM)
-1 freeh Free H+ of the horizon cmol+ kg 4 (PFH) horizon_bulk_dens_est Estimated bulk density of fine kg m-3 4 (PFH) earth if no measured bulk density exists horizon_bulk_dens_meas Measured bulk density of the kg m-3 4 ure fine earth in the horizon (PFH) horizon_c_organic_total Organic carbon content g kg-1 1, 4 (PFH) horizon_caco3_total Total calcium carbonate g kg-1 1, 4 (PFH) (CaCO3) content
-1 horizon_cec Cation exchange capacity cmol+ kg 1, 4 (PFH) (CEC) of the horizon horizon_clay Mass fraction of clay (0-2 µm g 100g-1 4, 7 (PFH) fraction) related to fine earth horizon_coarse_weight Mass percentage of coarse % 4 (PFH) fragments (stones and gravel with a diameter > 2 mm) horizon_elec_cond Electrical conductivity of the dS m-1 1, 4 (PFH) horizon
-1 horizon_exch_acid Exchangeable acidity of the cmol+ kg 4 (PFH) horizon
-1 horizon_exch_al Exchangeable aluminium of cmol+ kg 4 (PFH) the horizon
-1 horizon_exch_ca Exchangeable calcium of the cmol+ kg 1, 4 (PFH) horizon
-1 horizon_exch_fe Exchangeable iron of the cmol+ kg 4 (PFH) horizon
-1 horizon_exch_k Exchangeable potassium of cmol+ kg 1, 4 (PFH) the horizon
-1 horizon_exch_mg Exchangeable magnesium of cmol+ kg 1, 4 (PFH) the horizon
-1 horizon_exch_mn Exchangeable manganese of cmol+ kg 4 (PFH) the horizon
8 -1 horizon_exch_na Exchangeable sodium of the cmol+ kg 1, 4 (PFH) horizon horizon_limit_low The lower limit of the horizon cm 1 (PFH) depth horizon_limit_up The upper limit of the horizon cm 1 (PFH) depth horizon_n_total Total nitrogen content g kg-1 1, 4 (PFH) horizon_number Identification number of the 1 (PFH, SWA, SWR) horizon horizon_ph pH value of the soil horizon 1, 4 (PFH) horizon_sand Mass fraction of sand (63 – g 100g-1 4, 7 (PFH) 2000 µm fraction) related to fine earth horizon_silt Mass fraction of silt (2 – 63 g 100g-1 4, 7 (PFH) µm fraction) related to fine earth horizon_vertical Order number of the vertical 1 (PFH) subdivision in the horizon designation ksat Hydraulic conductivity at cm d-1 6 (SWR) saturation (AG Boden 2005) laboratory_id ID of laboratory (e.g. H45, 1 (LQA) B78, etc.) latitude Latitude of the plot in Degrees 1 (PLS) geographical coordinates Minutes (degrees, sexagesimal Seconds minutes, sexagesimal seconds), datum = WGS84, no projection (+/- DDMMSS) layer_limit_inferior The lower limit of the layer cm (SOM) depth layer_limit_superior The upper limit of the layer cm (SOM) depth laytype Type of layer: Mineral layer (SOM) (“Min”), Forest floor (“FF”) or peat layer (“Peat”)
9 longitude Longitude of the plot in Degrees 1 (PLS) geographical coordinates Minutes (degrees, sexagesimal Seconds minutes, sexagesimal seconds), datum = WGS84, no projection (+/- DDMMSS) loq Quantification limit (unit of 1, 8 (LQA) parameter) loq_half Half of the limit of 1, 8 (LQA) quantification matric_potential Matric potential hPa 4, 5 (SWA) moisture_content Moisture content by mass of % 4 (SOM) air dried sample vs. oven dried sample mvg_alpha Mualem/van Genuchten cm-1 4, 5 (SWR) parameter alpha (Van Genuchten et al. 1991) mvg_awc Plant available water capacity m3 m-3 4, 5 (SWR) (mvg_theta_fc minus mvg_theta_pwp) mvg_m Mualem / van Genuchten 4, 5 (SWR) parameter m (Van Genuchten et al. 1991) mvg_n Mualem / van Genuchten 4, 5 (SWR) parameter n (Van Genuchten et al. 1991) mvg_rsquared r²-value of the selected M/vG- actual paper (SWR) approximation in relation to all data points mvg_theta_fc Water content at field capacity m3 m-3 4, 5 (SWR) (volumetric fraction at pF 1.8) mvg_theta_pwp Water content at permanent m3 m-3 4, 5 (SWR) wilting point (pF 4.2) mvg_theta_sat Saturated water content m3 m-3 4, 5 (SWR) (volumetric fraction, Van Genuchten et al. 1991)
10 n_total Total nitrogen content g kg-1 4 (SOM) obstacle_depth Obstacle depth of the soil cm 1 (PRF) profile organic_carbon_total Organic carbon content g kg-1 4 (SOM) organic_layer_weight Total dry mass of the organic kg m-2 4 (SOM) layer other_obs Any additional observations Text 1 (LQA, PFH, PLS, PRF, SOM, relevant at the specified level: SWR ) (laboratory quality, horizons, plot, profile, layers, and pF- curves) part_size_clay Mass fraction of clay (0 - 2 μm) g 100g-1 4 (SOM) related to fine earth part_size_sand Mass fraction of sand (63 - g 100g-1 4 (SOM) 2000 ųm) related to fine earth part_size_silt Mass fraction of silt (2 - 63 g 100g-1 4 (SOM) μm) related to fine earth pf_total_datapoints Total number of data points actual paper (SWR) on soil water retention curves related to one fixed depth layer pf_total_replicates Total number of pF-curves per actual paper (SWR) layer on the plot (across SW profiles) pfh_id Code of reference profile on 1 (SWA) the plot used for horizon description ph_cacl2 pH measured in calcium 4 (SOM) chloride CaCl2 ph_h2o pH measured in water 4 (SOM) porosity Total porosity of the horizon Vol % 4 (PFH) rea_al Acid oxalate extractable Al mg kg-1 4 (SOM)
11 rea_fe Acid oxalate extractable Fe mg kg-1 4 (SOM) reacal Acid ammonium oxalate mg kg-1 4 (PFH) extractable aluminium content of the horizon reacfe Acid ammonium oxalate mg kg-1 4 (PFH) extractable iron content the horizon removal_comp Code removal compounds 1, 4 (LQA) replicate ID of the sample replicate at a 1 (SWA) given soil water profile and depth requali_info Requalification information 8 (LQA) (yes = 1, no = 0) ring_depth_lower Lower limit of the sampling cm 4, 5 (SWA) depth (distance below surface of the mineral soil) ring_depth_upper Upper limit of the sampling cm 4, 5 (SWA) depth (distance below surface of the mineral soil) ring_test_number ICP Forests Ring Test Number 1 (LQA) ring_test_particip Participated at ring Test (yes = (LQA) 1, no = 0) ring_test_result Percentage of results of ring % 1 (LQA) test within tolerable limits for each ring test ring-test_result_requali Percentage of results of ring % 1 (LQA) test within tolerable limits for each ring test in requalification rock_depth Rock depth of the soil profile cm 1 (PRF) rooting_depth Root depth of the soil profile cm 1 (PRF) sample_limit_low Lower limit of the sampling cm 4, 5 (SWR) depth below surface of the mineral soil
12 sample_limit_up Upper limit of the sampling cm 4, 5 (SWR) depth below surface of the mineral soil stocks_ff_c Total carbon stock in Forest t ha-1 actual paper (STO) Floor (OL, OF, OH layers combined) stocks_ff_n Total nitrogen stock in Forest t ha-1 actual paper (STO) Floor (OL, OF, OH layers combined) stocks_ff_p Total phosphorus stock in t ha-1 actual paper (STO) Forest Floor (OL, OF, OH layers combined) stocks_ff_s Total sulphur stock in Forest t ha-1 actual paper (STO) Floor (OL, OF, OH layers combined) stocks_min_c Total carbon stock between t ha-1 actual paper (STO) top of mineral soil (0 cm) and 100 cm or effective depth stocks_min_n Total nitrogen stock between t ha-1 actual paper (STO) top of mineral soil (0 cm) and 100 cm or effective depth stocks_min_p Total phosphorus stock t ha-1 actual paper (STO) between top of mineral soil (0 cm) and 100 cm or effective depth stocks_min_s Total sulphur stock between t ha-1 actual paper (STO) top of mineral soil (0 cm) and 100 cm or effective depth stocks_min30_c Total carbon stock between t ha-1 actual paper (STO) top of mineral soil (0 cm) and 30 cm of depth stocks_min30_n Total nitrogen stock between t ha-1 actual paper (STO) top of mineral soil (0 cm) and 30 cm of depth stocks_min30_p Total phosphorus stock t ha-1 actual paper (STO) between top of mineral soil (0 cm) and 30 cm of depth stocks_min30_s Total sulphur stock between t ha-1 actual paper (STO) top of mineral soil (0 cm) and 30 cm of depth
13 survey_year Year of the final laboratory YYYY (LQA, PFH, PRF, SOM, analysis or profile description STO, SWA)
sw_id ID of the soil water profile used 1 (SWA) for pF-sampling
thickness Vertical extension of the layer cm (SOM)
tot_al Total Al content mg kg-1 4 (SOM)
tot_ca Total Ca content mg kg-1 4 (SOM)
tot_fe Total Fe content mg kg-1 4 (SOM)
tot_k Total K content mg kg-1 4 (SOM)
tot_mg Total Mg content mg kg-1 4 (SOM)
tot_mn Total Mn content mg kg-1 4 (SOM)
tot_na Total Na content mg kg-1 4 (SOM)
totnsamples Total number of subsamples (SOM) on which aggregation is based
water_content_vol Water content of the sample at m3 m-3 4, 5 (SWA) a given matric potential (volumetric fraction)
Sources used
[1]: PCC (Project Coordinating Center of ICP Forests) (2012) Forms and explanatory items to be applied for data submission 2011 onwards, Version 2011n6, 30th October 2012. Thünen Institute, Hamburg [2a]: Food and Agriculture Organization of the United Nations (2006) IUSS Working Group WRB. World reference base for soil resources 2006. World Soil Resources Reports 103. ftp://ftp.fao.org/docrep/fao/009/a0510e/a0510e00.pdf - reproduced with permission
[2b]: Food and Agriculture Organization of the United Nations (2007) IUSS Working Group WRB. World reference base for soil resources 2006. First update 2007. World Soil Resources Reports 103. http://www.fao.org/fileadmin/templates/nr/images/resources/pdf_documents/wrb2007_red.pdf reproduced with permission
14 [2c]: IUSS Working Group WRB (2007) World Reference Base for Soil Resources 2006. Erstes Update 2007. Deutsche Ausgabe. – Übersetzt von Peter Schad. Herausgegeben von der Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover. http://www.bgr.bund.de/DE/Themen/Boden/Produkte/Schriften/Downloads/WRB_deutsche_Ausga be.pdf?__blob=publicationFile
[3]: FSEP (Expert Panel on Soil), FSCC (Forest Soil Coordinating Centre) (2006): Sampling and Analysis of Soil. Part IIIa, 26 pp. In: Manual on methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests, UNECE, ICP Forests, Hamburg. ISBN: 978-3-926301-03-1. [http://www.icp-forests.org/Manual.htm]
[4]: Cools, N, De Vos, B (2010) Sampling and Analysis of Soil. Manual Part X, 208 pp. In: Manual on methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests, UNECE, ICP Forests, Hamburg. ISBN: 978-3-926301-03-1. [http://www.icp- forests.org/Manual.htm]
[5]: Futmon (2009) Field Protocol: Determination of the soil water retention characteristics V 1.1. Instituut voor Natuur- en Bosonderzoek, Geraardsbergen, Belgium http://www.futmon.org/sites/default/files/documenten/field_prot_SoilWater_v1_150509.pdf Accessed 14 April 2016
[6]: AG Boden (2005) Bodenkundliche Kartieranleitung. Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover (cited excerpt: adapted and translated)
[7]: Food and Agriculture Organization of the United Nations (2006) Jahn, R, Blume, H-P, Asio, VB, Spaargaren, O, Schad, P, Langohr, R, Brinkman, R, Nachtergaele, FO, Krasilnikov, RP. Guidelines for Soil Description and Classification, 4th edition. ftp://ftp.fao.org/agl/agll/docs/guidel_soil_descr.pdf reproduced with permission [8]: König N, Kowalska A, Brunialti G, Ferretti M, Clarke N, Cools N, Derome J, Derome K, De Vos B, Fuerst A, Jakovljevič T, Marchetto A, Mosello R, O’Dea P, Tartari GA, Ulrich E, 2010: Quality Assurance and Control in Laboratories. 53 pp. Part XVI. In: Manual on methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests. UNECE, ICP Forests Programme Co-ordinating Centre, Hamburg. ISBN: 978-3-926301-03-1. [http://www.icp-forests.org/Manual.htm]
[9] Finke, P. Hartwich, R., Dudal, R., Ibàñez, J., Jamagne, M., King, D., Montanarella, L., Yassoglou, N. 2001. Georeferenced soil database for Europe. Manual of Procedures. Version 1.1. Edited by European Soil Bureau Scientific Committee, Research Report N°5. EUR 18092 EN.
[10] Munsell Soil Color Book. Munsell.com
15
Forms and Explanatory Items To be applied for data submission 2011 onwards Version 2011n6 Last update 30 October 2012
Contents List of Abbreviations and Acronyms ...... 3 1 Introduction ...... 4 2 General Remarks ...... 4 3 Amendment Index ...... 6 3.1 Amendments to Version 1.0f and 1.0g ...... 6 3.2 Amendments to Version 1.0e ...... 6 3.3 Amendments to Version 1.0d ...... 6 3.4 Amendments to Version 1.0c ...... 6 3.5 Amendments to Version 1.0b (printed Task Force Meeting 2010 in Garmisch Partenkirchen) ...... 6 3.6 Amendments to last form definitions for data years 2009 and 2010 ...... 7 4 Forms ...... 15 4.1 Part II System Installation ...... 15 4.2 Part IV Crown Condition ...... 19 4.3 Part VAssessment of Growth and Increment ...... 23 4.4 Part VI Phenological Observations ...... 31 4.5 Part VII Assessment of Ground Vegetation ...... 34 4.6 Part VIII Assessment of Ozone Injury ...... 36 4.7 Part IX Meteorological Measurements ...... 40 4.8 Part X Sampling and Analysis of Soil ...... 44 4.9 Part XI Soil Solution Collection and Analysis ...... 53 4.10 Part XII Sampling and Analysis of Needles and Leaves ...... 57 4.11 Part XIII Sampling and Analysis of Litterfall ...... 60 4.12 Part XIV Sampling and Analysis of Deposition ...... 63 4.13 Part XV Monitoring of Air Quality ...... 67 4.14 Soil water ...... 72 4.15 Ground Vegetation Biomass and Nutrients Analyses ...... 74 4.16 Leaf Area Index (LAI) and Radiation Measurements ...... 77
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5 Explanatory Items ...... 81 6 Literature ...... 178
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List of Abbreviations and Acronyms
AAS Atomic Absorption Spectrometer BD Bulk Density BS Base Saturation CEC Cation Exchange Capacity DAR-Q Data Accompanying Report Questionnaire
Ec Electrical conductivity F Fermentation horizon FAO Food and Agriculture Organization FES Flame Emission Spectrometer GPS Global Positioning System H Humus horizon ICP Inductivity Coupled Plasma Spectrometer IRM International Reference Material ISO International Organization for Standardization JRC Joint Research Centre, Ispra, European Commission L Litter horizon LAI Leaf Area Index LRM Local Reference Material M Mandatory parameter MBD Mineral Bulk Density NFC National Focal Centre of the Intensive Monitoring Programme NRM National Reference Material O Optional parameter OM Organic Matter QA/QC Quality Assurance and Quality Control SA Soil Analysis method SAG Scientific Advisory Group of the Intensive Monitoring Programme SD Standard Deviation SFC Standing Forestry Committee WRB World Reference Base for Soil Resources
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1 Introduction
This document concludes all forms which are used for data submission from the year 2009 onwards in the frame of the FutMon project as well as of the ICP Forests programme. Changes which are made in comparison with the latest adopted version of the respective ICP Forests forms are highlighted by using bold font and blue colour. In addition all amendments and changes are summarized in the amendment index.
2 General Remarks
Some general remarks are made here in order to allow a high quality data submission: As the combination of parameters which are submitted with a specific form may vary over time due to manual changes it is necessary to document in the submission files which fields/parameters are submitted with this file. The submitting project partners will do so by including a first line into each submission file which starts with an exclamation mark followed by a comma separated list of the submitted fields/parameters. Example for first (comment) line submitted within the file XXGENER.PLT: !Sequence, country, plot, latitude, longitude, X, Y, altitude_m, altitude, plot_design, orientation, slope,date_installation, plot_size, status_plot, status_NFI, other_observations Those fields which are expected to be continuous and not to change over time are underlined. Fields which are part of the key of the respective form/table are printed in bold font. Thus, each line in a submitted file must be identified by its own and unique combination of the values in those key fields. Further comments may made before the data specification line but will not be tested automatically during the validation process. Each comment paragraph or line has to start with an exclamation mark. The last comment line before the first data record must be the data specification line which is specified on top of each form (s. below). Only in case of the last table fields which are named “other_observations” (or similar) please use left alignment. Data submission will be done using the submission module of the ICP Forests data base. The data will be submitted survey by survey and year by year. Thus, each project partner has to submit a complete set of a survey of a specific year to the submission module. This set includes in general a reduced plot file, data files, data accompanying reports (word documents) and in case of surveys with data from laboratory analyses a laboratory QA file (.LQA). The data will be submitted using fixed format ASCII files. The formats are described in this document including start and end column of each parameter. For each parameter the number of digits is defined in the forms below. Metric values are not defined to have a specific number of decimal units but will be stored in the database as floating point values. Thus, a parameter with 4 digits could have values as: “3456” or “22.4” or “2.63” or “02.6” or “ 2.6” or “2.6 “ or “.123” The parameter values are separated by blanks. A decimal point is used.
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In case that not all digits are needed for data submission the data should be stored right-aligned. If e.g. a field with 5 digits is defined for a form and the three digit code "BHI" should be submitted in this specific field it is recommended to insert it in the data submission file in form of " BHI" instead of "BHI ". In case of values which are too high to be submitted with the specified number of digits (e.g. “10243.1” in case of a parameter with only 4 digits “9999” should be submitted instead and the true value (“10243.1”) should be submitted in the text field “other observations”. This should be done following the form “VALUE FOR is
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3 Amendment Index
3.1 Amendments to Version 1.0f and 1.0g
a) TRE, TRC: Discolouration deleted (now to be submitted via TRF and TRD).
b) GENER.PL1 as well as XX2011.STA and XX2011.ST1 created
c) date_analysis in FOM changed to be key value in order to enable multiple samples per year
3.2 Amendments to Version 1.0e
d) LA: LAM and LAP: Text in forms was revised in order to adapt name specification for photo files to the format of the explanatory item(153).
3.3 Amendments to Version 1.0d
e) MM, MEO: The unit for Matric Potential in explanatory item (93) was corrected to hPa (as already stated in explanatory item (95) instead of kPa.
3.4 Amendments to Version 1.0c
f) SO, SOM and LQA: Parameter It was corrected in parameter list in explanatory item (141)that parameter Ca_CO3 is specified to be “Carbonates” instead of C_CO3. In addition, in form SOM carbonates was amended by “Ca_CO3”: Carbonates (g/kg Ca_CO3)
g) LQAs: In all LQA forms the format for the coefficient of variation of the control charts was changed from I 3 to F 3 in order to allow for submission of values from .01 to 999. Lower or higher values are to be reported as defined in the General Remarks section for higher values.
3.5 Amendments to Version 1.0b (printed Task Force Meeting 2010 in Garmisch Partenkirchen)
a) GR, status of tree: explanatory item (120), explanation of code 14 now reads “cut, stump found but reason unknown” instead of “cut, reason unknown”. Explanation of code 24 now reads “breakage of the tip(s) or part of crown broken” instead of “breakage of the tip(s) of the tree (shoot)”.
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b) System Installation, XXGENERa.PLT (Level II) und XXGENERaLI.PLT (LevelI):Code list for ownership was revised in Explanatory item (23) and the format was changed from I 1 to I 2.
3.6 Amendments to last form definitions for data years 2009 and 2010 Survey Form Description SI GENER.PLT The fields
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Survey Form Description SI, C1, G1 GENER.PL1, The width of field
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Survey Form Description CC TRC Field
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Survey Form Description FO FOM Form FOM: Fields for Sample numbers (Tree species + leaves type) were deleted from the form. The tree species and leaves type are now to be submitted with the new form FOT. As many lines per sample have to be submitted as trees were sampled, each line corresponds to a sample tree.>. In addition the new field
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Survey Form Description G1 XX2011.G1M New form on Growth periodic measurement data (Level I) introduced GR IRA, IRH, IRM Form IRA for submission of data from tree ring analyses was replaced by the forms IRH (header data) and IRM (ring data) GR INV Fields
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Survey Form Description GV PLV, VEM New field
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Survey Form Description OZ LSS Species code “000.000.000” and scientifc name “Empty”were introduced in order to indicate empty rectangles. OZ LSS Field “Perennial/Annual” has been deleted as for the LESS, only woody species are reported now. OZ PLL The field
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Survey Form Description LA LAC The form LAC was shifted to System installment (SI). LA LAI The form LAI has been introduced for the submission of summarized LAI results. LA LAM The fields
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4 Forms
4.1 Part II System Installation
XXGENER.PLT Contents of file with the information on Plot level Level II The file for system installation XXGENER.PLT has to be submitted if new plots have to be defined or in case that respective data have to be changed in the data base. Only the information concerning new plots or plots with information updates has to be submitted. All other plots may be re-submitted with the XXGENER.PLT file.Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, latitude, longitude, X, Y, altitude_m, altitude, plot_design, orientation, slope, date_installation, plot_size, status_plot, status_NFI, other_observations Ref_ o/m Column Description Format Item # Tab 1 – 4 Sequence number of plots (1 to 9999) I 4 m Country Code (France = 01, Belgium = 02, m 6 – 7 I 2 X (1) etc.) 9 – 12 Observation plotnumber (max. 9999) I 4 (2) m 14 – 20 Latitude in +DDMMSS (e.g.+505852) C 7 (4) m Longitude in (+ or -)DDMMSS (e.g. m 22 – 28 C 7 (4) +035531) X coordinate local plot centre (metric o 30 – 37 F 8 (6) coordinate west – east ) Y coordinate local plot centre (metric o 39 – 46 F 8 (6) coordinate south – north) Altitude in meter (e.g. measured with o 48 – 51 I 4 GPS) 53 – 54 Altitude (in 50 metre classes from 1 to 51) I 2 X (32) m 56 – 58 Plot design I 3 X (5) m 60 Orientation (N =1, NE = 2, etc.) I 1 X (33) m 62 – 63 Slope in degree I 2 m 65 – 70 Installation date in DDMMYY Date (3) m 72 – 77 Total plot size (in ha) F 6 (39) m 79 Plot status I 1 X (24) m 81 NFI status I 1 X (25) o Number of trees in total plot I 4 (39) Size of sub-plot (in ha) F 6 (38) Mean age of dominant storey I 2 X (30) (in 20 year classes from 1 to 8) Main tree species I 3 X (43)
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Yield estimate – absolute I 1 X (40) Yield estimate – relative I 1 X (40) 83 – 122 Other observations (text) C 40 (177)
XXGENER.PL1 Contents of file with the information on Plot level Level I The file for system installation on Level I XXGENER.PL1 has to be submitted if new plots have to be defined or in case that respective data have to be changed in the data base. Only the information concerning new plots or plots with information updates has to be submitted. All other plots may be re-submitted with the XXGENER.PLT file.Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, latitude, longitude, X, Y, altitude_m, altitude, plot_design, orientation, slope, date_installation, plot_size, status_plot, status_NFI, other_observations Ref_ Item o/m Column Description Format Tab # 1 – 4 Sequence number of plots (1 to 9999) I 4 m Country Code (France = 01, Belgium = m 6 – 7 I 2 X (1) 02, etc.) 9 – 14 Observation plotnumber (max. 999999) I 6 (2) m 16 – 22 Latitude in +DDMMSS (e.g.+505852) C 7 (4) m Longitude in (+ or -)DDMMSS (e.g. m 24 – 30 C 7 (4) +035531) X coordinate local plot centre (metric o 32 – 39 F 8 (6) coordinate west – east ) Y coordinate local plot centre (metric o 41 – 48 F 8 (6) coordinate south – north) Altitude in meter (e.g. measured with o 50 – 53 I 4 GPS) 55 – 56 Altitude (in 50 metre classes from 1 to 51) I 2 X (32) m 58 – 60 Plot design I 3 X (5) m 62 Orientation (N =1, NE = 2, etc.) I 1 X (33) m 64 – 65 Slope in degree I 2 o 67 – 72 Installation date in DDMMYY Date (3) m 74 – 79 Total plot size (in ha) F 6 (39) m 81 Plot status I 1 X (24) o 83 NFI status I 1 X (25) m 85 – 124 Other observations (text) C 40 (177) o – optional, m - mandatory
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XX2012.STA (Level II) and XX2011.ST1 (Level I) contents of file with the information on stand description – every five years In case that at least one parameter has to be updated please send the complete list of all parameters and not only the updated parameter(s) of the resepective plot(s). Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, history, prev_landuse, origin_stand, tree_species, tspec_mix, top_height, det_toph, foresttype, age, n_layers, cov_layers, canclosure, status_protect, fence, nontimb_util, man_type, int_man, man_meth, owner, other_observations Ref_ Item Level I Level II Column Description Format Tab # 1 – 4 Sequence number of plots I 4 Country Code (France = 01, 6 – 7 I 2 X (1) Belgium = 02, etc.) 9 – 14 Observation plotnumber I 6 (2) 16 Stand history I 1 X (7) o m 18 Previous land use I 1 X (8) o m 20 Origin of actual stand I 1 X (9) o m 22 – 24 Main tree species I 3 X (42) m m 26 Type of tree species mixture I 1 X (10) o m 28 – 32 Top height (in meters) F 5 (11) o m 34 – 35 Determination of top height I 2 X (12) o m 37 – 38 Forest type I 2 X (13) m m 40 Age class I 1 X (34) m m 42 Number of tree layers I 1 X (14) o m 44 – 46 Coverage of tree layers I 3 (15) o m 48 – 50 Canopy closure I 3 (16) m m 52 Protection status I 1 X (17) o m 54 Fencing I 1 X (18) o m 56 Non-timber utilisation I 1 X (19) o m 58 Management type I 1 X (20) o m 60 Intensity of management I 1 X (21) o m 62 Management method I 1 X (22) o m 64 – 65 Forest ownership I 2 X (23) o M 67 – 106 Other observations (text) C 40 (177) o – optional, m – mandatory
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XX2009.LAC coordinates of LAI measurement points and other surveys (Level II) (former LAI form) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot,survey, device,x_coordinate, y_coordinate, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number of plots (1 to 9999) I 4 6 – 7 Country Code (France = 01, Belgium = 02, etc.) I 2 X (1) 9 – 12 Observation plotnumber (max. 9999) I 4 (2) 14 – 15 Survey C 2 X (26) Device_ ID (e.g. measurement point on LAI, trap 17 – 19 C 3 (27) number on Litterfall, sampler on deposition survey) 21 – 28 X coordinate (metric system; relative plot coordinate) F 8 (6) 30 – 37 Y coordinate (metric system; relative plot coordinate) F 8 (6) 39 – 78 Other observations (text) C 40 (177)
XX2011.TCO Tree coordinates (Level II) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, date, tree, tree_species, x_coordinate, y_coordinate, tree_within, tree_status, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number of plots (1 to 9999) I 4 6 – 7 Country Code (France = 01, Belgium = 02, etc.) I 2 X (1) 9 – 12 Observation plotnumber (max. 9999) I 4 (2) 14 – 19 Date of survey in DDMMYY (e.g. 050509) 21 – 24 Tree number C 4 (41) 26 – 28 Tree species I 3 X (42) X coordinate (metric system; relative plot 30 – 37 F 8 (6) coordinate) Y coordinate (metric system; relative plot 39 – 46 F 8 (6) coordinate) 48 Tree within Level II plot (Y/N) C 1 (28) 50 Status of Tree I 1 X (29) 52 – 91 Other observations (text) C 40 (177)
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Part IV CC & C1 Visual Assessment of Crown Condition
4.2 Part IV Crown Condition
XX2012.PLO Contents of file with the information on Plot level to be used in combination with the tree vitality inventory Level I Each data file has to start with a comment line. This line starts with an exclamation mark !Sequence, country, plot, date,latitude, longitude, team_ID, water, humus, altitude, orientation, mean_age, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number of plots (1 to 9999) I 4 6 – 7 Country code I 2 X (1) 9 – 14 Observation plotnumber (max. 999999) I 6 (2) 16 – 21 Date Date (3) 23 – 29 Latitude C 7 (4) 31 – 37 Longitude C 7 (4) 39 – 43 Field team ID I 5 (88) 45 Water availability I 1 X (30) 47 Humus type I 1 X (31) 49 – 50 Altitude I 2 X (32) 52 Orientation I 1 X (33) 54 – 55 Mean age of dominant storey I 2 X (34) 57 – 96 Other observations (text) C 40 (177)
XX2012.TRE Crown condition parameters Level I Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, date, tree,tree_species,removal_mortality, defol, discol, fruiting_assess, assessable crown, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number of trees (1 to 99999) I 5 7 – 12 Observation plot number (max. 999999) I 6 (2) 14 – 19 Date of survey in DDMMYY (e.g. 220704) Date (3) 21 – 24 Tree number (as marked during installation) I 4 (41) 26 – 28 Species I 3 X (42) 30 – 31 Removals & mortality: status of tree I 2 X (43)
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Column Description Format Ref_Tab Item # 33 – 35 Defoliation (0,5,10,15 ... 95,99,100%) I 3 X (48) Discolouration (0,1,2,3,4) [optional] Fruiting in assessable crown (1.1, 1.21,2,3) F 3 X (51) 37– 39 [optional] 41 Assessable crown I 1 X (44) 43 – 82 Other observations (text) C 40 (177)
XX2012.TRF Damage parameters Level I Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, date, tree, affected_part, symptom, symptom_spec, crown_loc, damage_age, cause,cause_sc_name, extent, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number of trees (1 to 99999) I 5 7 – 12 Observation plot number (max. 999999) I 6 (2) Date of survey in DDMMYY (e.g. 14 – 19 Date (3) 220704) Tree number (as marked during 21 – 24 I 4 (41) installation) Specification of affected part 26 – 27 I 2 X (54) (11, ..., 34) 29 – 30 Symptom (01,..., 22) I 2 X (55) Specification of symptom (31, ..., 67) 32 – 33 I 2 X (55) [optional] 35 Location in crown (1,2,3,4) [optional] I 1 X (54) 37 Age of damage (1,2,3) [optional] I 1 X (56) 39 – 43 Cause (e.g. 81001) I 5 X (57) Scientific name of cause (e.g. 45 – 51 C 7 X (58) LOPHSED) 53 Extent (0,1,2,3,4,5,6,7) I 1 X (59) 55 – 94 Other observations (text) C 40 (177)
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XX2012.PLT Contents of file with the information on plot level to be used with the crown assessment on Level II Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, date,latitude, longitude, altitude, team_ID, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number of plots (1 to 9999) I 4 6 – 7 Country code I 2 X (1) 9 – 12 Observation plot # I 4 (2) 14 – 19 Date of assessment (DDMMYY) Date (3) 21 – 27 Latitude in + DDMMSS (e.g. +505852) C 7 (4) Longitude in (+ or -) DDMMSS 29 – 35 C 7 (4) (e.g. -035531) Altitude (in 50 meter classes 37 – 38 I 2 X (32) from 1 to 51) 40 – 44 Field team ID I 5 (88) 46 – 85 Other observations (text) C 40 (177)
XX2012.TRC Crown condition parameters Level II All parameters listed are mandatory if not otherwise stated.Only one data line is expected per tree and assessment date. Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, date, tree,tree_species, removal_mortality, social_class, shading_crown, visibility, defol, discol, flowering_assess, flowering_whole, fruiting_assess, fruiting_whole, transparency, form_crown, secondary_shoots,CDRD_N, shoot_arch, tree_age_class, method_age, as_crown, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number of trees (1 to 99999) I 5 7 – 10 Observation plot number (max. 9999) I 4 (2) 12 – 17 Date of survey in DDMMYY (e.g. 220704) Date (3) 19 – 22 Tree number (as marked during installation) I 4 (41) 24 – 26 Species I 3 X (42) 28 – 29 Removals & mortality: status of tree I 2 X (43) 31 Social class (1,2,3,4,5) I 1 X (45) 33 Crown shading (1,2,3,4,5,6) [optional] I 1 X (46) 35 Visibility (1,2,3,4) I 1 X (47) 37- 39 Defoliation (0,5,10,15 ... 95,99,100%) I 3 X (48) 41 Discolouration (0,1,2,3,4) [empty] I 1 X 43 Flowering in assessable crown (1,2,3) [optional] I 1 X (50)
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Column Description Format Ref_Tab Item # 45 Flowering in whole crown (1,2,3) [optional] I 1 X (50) 47 – 49 Fruiting in assessable crown (1.1, 1.21,2,3) [optional] F 3 X (51) 51 – 53 Fruiting in whole crown (1.1, 1.21,2,3) [optional] F 3 X (51) Foliage transparency (0,5,10,15,...,95,99,100) I 3 X (49) 55 – 57 [optional] 59 – 60 Crown form (11 to 39) [optional] I 2 X (53) 62 Secondary shoots & epicormics (1,2,3) [optional] I 1 X (52) Crown related distance to neighbour; F 5 X (38) 64 – 68 CDRD_N[optional] 70 Apical shoot architecture (beech only)[optional] I 1 X (36) 72 Tree age class [optional] I 1 X (35) 74 Method of age assessment[optional] I 1 X (36) 76 Assessable crown[optional] I 1 X (44) 78 – 117 Other observations (text) C 40 (177)
XX2012.TRD Damage parameters Level II All parameters listed are mandatory. Due to the fact that more than one damage per tree may occur at the same time submitted TRD files may have more than one line per tree. Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, date, tree, affected_part, symptom,symptom_spec,crown_loc, damage_age, cause,cause_sc_name, extent, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number of trees (1 to 99999) I 5 7 – 10 Observation plot number (max. 9999) I 4 (2) 12 – 17 Date of survey in DDMMYY (e.g. 220704) Date (3) 19 – 22 Tree number (as marked during installation) I 4 (41) 24 – 25 Specification of affected part (11, ..., 34) I 2 X (54) 27 – 28 Symptom (01,..., 22) I 2 X (55) 30 – 31 Specification of symptom (31, ..., 67) I 2 X (55) 33 Location in crown (1,2,3,4) I 1 X (54) 35 Age of damage (1,2,3) I 1 X (56) 37 – 41 Cause (e.g. 81001) I 5 X (57) 43 – 49 Scientific name of cause (e.g. LOPHSED) C 7 X (58) 51 Extent (0,1,2,3,4,5,6,7) I 1 X (59) 53 – 92 Other observations (text) C 40 (177)
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Part V GR and G1
4.3 Part V Assessment of Growth and Increment
Tree Coordinates of the Growth plots have to be submitted with XX2011L1.TCO for Level I and XX2011.TCO for Level II plots (optional).
XX2011.G1P Content of reduced plot file to be used for increment on Level I !Sequence, country, plot, date,latitude,longitude,sample_plot_size,trees_G1, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number of plots (1 to 9999) I 4 6 – 7 Country code (France = 01, Belgium = 02, etc.) I 2 X (1) 9 – 14 Plot number (maximum 999999) I 6 (2) 16 – 21 Date of observation in DDMMYY (e.g. 220694) Date (3) 23 – 29 Latitude in +DDMMSS (e.g. + 501027) C 7 (4) 31 – 37 Longitude in + or –DDMMSS (e.g. – 011532) C 7 (4) 39 – 44 Growth (= sample) plot size in hectares F 6 (39) 46 – 50 Number of all standing trees in Growth plot. I 5 (75) 52 – 91 Other observations (text) C 40 (177)
XX2011.G1M Contents of file with increment information – periodic measurements on Level I+++) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, tree,tree_species, diameter, diameter_qc, diameter2, diameter2_qc, bark, bark_qc, height, height_qc, volume, volume_qc, crown_base_height, crown_base_qc, crown_width, crown_widht_qc, removal, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number records (1 to 99999) I 5 7 – 12 plot number (maximum 999999) I 6 (2) 14 – 17 Tree number C 4 (41) 19 – 21 Species I 3 X (42) 23 – 27 Diameter at breast height (dbh) F 5 (60) 29 Diameter quality code I 1 X (74) 31 – 35 Diameter 2 (dbh2) +) F 5 (60)
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Column Description Format Ref_Tab Item # 37 Diameter 2 quality code I 1 X (74) 39 – 41 Bark [cm] F 3 (61) 43 Bark quality code I 1 X (74) 45 – 48 Height rounded to the nearest 0.1 (62) F 4 meters (maximum 99.9 m) 50 Height quality code I 1 X (74) 52 – 57 Tree volume (63) F 6 [m3] 59 Tree volume quality code I 1 X (74) 61 – 64 Height to crown base rounded to F 4 (64) the nearest 0.1 meters [m] ++) 66 Height to crown base quality code I 1 X (74) 68 – 71 Crownwidth rounded to the nearest F 4 (65) 0.1 meters [m] 73 Crown width quality code I 1 X (74) 75 – 76 Status, mortality and removal code I 2 X (76) 78 – 117 Other observations (text) C 40 (177) +) when calipers are used ++) when tree height is measured and the crown base is visible +++) no submission of data on old dead trees (not even a line with the tree number and/or the removal code; newly dead/removed trees have to be submitted only with its tree number and the respective status/removal/mortality code.
XX2012.PLI Contents of reduced plotfile to be used for increment on Level II Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, date, latitude, longitude, sample_plot_size, trees_GR, other_observations Item Column Description Format Ref_Tab # 1 – 4 Sequence number of plots (1 to 9999) I 4 6 – 7 Country code (France = 01, Belgium = 02, etc.) I 2 X (1) 9 – 12 Plot number (maximum 9999) I 4 (2) 14 – 19 Date of observation in DDMMYY (e.g. 220694) Date (3) 21 – 27 Latitude in +DDMMSS (e.g. + 501027) C 7 (4) 29 – 35 Longitude in + or –DDMMSS (e.g. – 011532) C 7 (4) 37 – 42 Growth (= sample) plot size in hectares F 6 (39) 44 – 48 Number of all standing trees (living and newly I 5 (75) dead trees) in Growth plot. The total number of trees (shoots in coppice forests) in the growth plot.
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Item Column Description Format Ref_Tab # 50 – 89 Other observations (text) C 40 (177)
XX2012.IPM Contents of file with increment information – periodic measurements on tree level+++) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, tree,tree_species, diameter, diameter_qc, diameter2, diameter2_qc, bark, bark_qc, height, height_qc, volume, volume_qc, crown_base_height, crown_base_qc, crown_width, crown_width_qc, removal, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number records (1 to Mandatory I 5 99999) 7 – 10 plot number (maximum 9999) I 4 (2) Mandatory 12 – 15 Tree number C 4 (41) Mandatory 17 – 19 Species I 3 X (42) Mandatory 21 – 25 Diameter F 5 (60) Mandatory 27 Diameter quality code I 1 X (74) 29 – 33 Diameter 2 F 5 (60) Mandatory+) 35 Diameter 2 quality code I 1 X (74) 37 – 39 Bark [cm] F 3 (61) Optional 41 Bark quality code I 1 X (74) 43 – 46 Height rounded to the nearest 0.1 (62) Optional F 4 meters (maximum 99.9 m) 48 Height quality code I 1 X (74) 50 – 55 Tree volume (63) Optional F 6 [m3] 57 Tree volume quality code I 1 X (74) 59 – 62 Height to crown base rounded to (64) Mandatory++) F 4 the nearest 0.1 meters [m] 64 Height to crown quality code I 1 X (74) 66 – 69 Crownwidth rounded to the (65) Optional F 4 nearest 0.1 meters [m] 71 Crown width quality code I 1 X (74) 73 – 74 Status, Mortality and removal X (76) Mandatory+++) I 2 code 76 – 115 Other observations (text) C 40 (177) Optional +) when calipers are used ++) when tree height is measured and the crown base is visible Page 25/178 40
+++) no submission of data on old dead trees (not even a line with the tree number and/or the removal code; newly dead/removed trees have to be submitted only with its tree number and the respective status/removal/mortality code.
XX2012.INV Contents of reduced plot file to be used to report the results on plot level for periodic plot wise growth data Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, latitude, longitude, altitude, date, tree_species, trees_remaining, trees_newlydead, trees_removed, volume_stemwood_remaining, volume_stemwood_newlydead, volume_stemwood_removed, diameter_basal, height_basal, top_height_abs, n_largest, top_height_rel, per_rel_top_height, other_observations Column Description Format Ref_Tab Item # 1- 4 Sequence number of plots (1 to 9999) I 4 6 – 7 Country Code (France = 01, Belgium = 02, etc.) I 2 X (1) 9 – 12 Plotnumber (max. 9999) I 4 (2) 14 – 21 Latitude in +DDMMSS (e.g.+505852) C 7 (4) 22 – 28 Longitude in (+ or -)DDMMSS (e.g. +035531) C 7 (4) 30 – 31 Altitude (in 50 meter classes from 1 to 51) I 2 X (32) 33 – 38 Date of sampling in DDMMYY (e.g. 221199) Date (3) 40 – 42 Tree species or group of tree species I 3 (70) 44 – 48 Number of remaining trees (alive trees only) in I 5 (71) Growth plot calculated per hectare 50 – 54 Number of newly dead trees in Growth plot I 5 (71) calculated per hectare 56 – 60 Number of removed trees (removed = alive in I 5 (71) previous ass. trees missing since last inventory) in Growth plot calculated per hectare 62 – 66 Stemwood volume (remaining = alive trees only) F 5 (68) [m3/ha] 68 – 72 Stemwood volume (newly dead) [m3/ha] F 5 (68) 74 – 78 Stemwood volume (removed = alive in previous F 5 (68) ass. trees missing since last inventory ) [m3/ha] 80 – 84 Diameter of basal area mean tree (remaining = F 5 (72) alive trees only)rounded to the nearest 0.1 centimeters [cm] 86 – 90 Height of basal area mean treerounded to the F 5 (72) nearest 0.1 meters [m] 92 – 96 Top height absolute rounded to the nearest 0.1 F 5 (73) meters [m]
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Column Description Format Ref_Tab Item # 98 – 101 Number of largest trees absolute top height I 4 (73) was calculated for (e.g. “100”) 103 – 107 Top height relative rounded to the nearest 0.1 F 5 (73) meters [m] 109 – 112 Percentage of largest trees relative top height F 4 (73) was calculated for (e.g. “10.5”) 114 – 153 Other observations (text) C 40 (177)
XX2012.IRH Header information – tree ring analysis and stemdisk analysis (optional; together with IRM replacing old IRA form) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, tree, tree_species, repetition, date_analyses, year_most_recent, tree_rings, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number (1 to 9999) I 4 6 – 9 Plot number (maximum 9999) I 4 (2) 11 – 14 Tree number with initial R for Ring C 4 (152) analysis and D for Disk sampling 16 – 18 Tree species I 3 X (42) 20 – 21 Repetition (e.g. four lines with “1”, “2”, I 2 “3”, or “4” in case of four cores, one line in file with “1” in case of a single core or only one direction on stem disc measured) 23 – 28 Date analyses (DDMMYY) Date (3) 30 – 33 Most recent year I 4 (year of ring with number “1“ in form IRM) 35 – 38 Number of tree rings (number of I 4 rows/lines in form IRM related to this tree and repetition) 40 – 79 Other observations (text) C 40 (177)
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XX2011.IRM Measurements – tree ring analysis and stemdisk analysis (optional) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, tree, repetition, tree_ring, ring_width, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number (1 to 9999) I 4 6 – 9 Plot number (maximum 9999) I 5 (2) 11 – 14 Tree number with initial R for Ring C 4 (152) analysis and D for Disk sampling 16 – 17 Repetition (e.g. 1, 2, 3, 4 in case of four I 2 cores, “1” in case of a single core or a stemd disc analysis) 19 – 22 Number of ring (starting with “1” for I 4 most recent ring of each combination of plot, tree and repectition) 24 – 28 Tree ring width in [0.01 mm] I 5 (e.g. “376” means 3.76 mm; “-9” in case of a “lost” tree ring) 30 – 69 Other observations (text) C 40 (177)
XX2012.IRP Form to be used for submission of diameter measurements (girthband or dendrometer) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, tree, date, diameter, time, measurement_average, dendrometer, sensor_exchanged, other_observations Column Description Format Ref_Tab Item # 1 - 6 Sequence number (1-999999) I 6 8 – 9 Country code I 2 X (1) 11 – 14 Plot Number I 4 (2) 16 – 19 Tree number (as marked during installation; I 4 (41) same as in .TRC; if not in TRC same as IPM-tree number) 21 – 26 Date of Assessment Date (3) 28 – 34 Actual diameter (girthband or dendrometer F 7 measurement) or diameter of period [cm] 36 – 41 Time of diameter measurement or reference Time time for which period diameter was calculated [HHMMSS] (e.g. 094357) 43 Measurement (code 1) or period value (2) I 1 X (77)
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Column Description Format Ref_Tab Item # 45 – 47 Continuous dendrometer (point dendrometer C 3 X (78) code: 1.1; circumference dendrometer code: 1.2) or permanent girthband measurement (code: 2) 49 Sensor was exchanged before this Y/N measurement or girthband adjusted [Yes=Y, No = N] 51 – 90 Other observations C 40 (177)
XX2007.IEV Contents of evaluated data on increment (optional) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, trees, basal_plot_per, volume_plot_per, basal_plot, volume_plot, thinning_5, basal_5, volume_5, thinning_10, basal_10, volume_10, thinning_15, basal_15, volume_15, thinning_20, basal_20, volume_20, thinning_25, basal_25, volume_25, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number I 4 6 – 9 Plot number (maximum 9999) I 4 (2) 11 – 14 Number of trees per plot (40) I 4 (maximum 9999 trees per plot) 16 – 20 Basal area per plot (67) F 5 (maximum 999.9 m2/plot) 22 – 26 Volume per plot (68) F 5 (maximum 999.9 m3/plot) above: periodic measurements below: evaluation of ring and stem disk samples 28 – 32 Basal area per plot (67) F 5 (maximum 999.9 m2/plot) 34 – 38 Volume per plot (68) F 5 (maximum 999.9 m3/plot) 40 Thinning between now and 5 years ago (yes (69) I 1 = 1, no = 0) 42 – 46 Basal area per plot 5 years ago (maximum (67) F 5 999.9 m2/plot) 48 – 52 Volume per plot 5 years ago (maximum (68) F 5 999.9 m3/plot) 54 Thinning between 5 and 10 years ago (yes = (69) I 1 1, no = 0) 56 – 60 Basal area per plot 10 years ago (maximum (67) F 5 999.9 m2/plot)
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Column Description Format Ref_Tab Item # 62 – 66 Volume per plot 10 years ago (maximum (68) F 5 999.9 m3/plot) 68 Thinning between 10 and 15 years ago (yes (69) I 1 = 1, no = 0) 70 – 74 Basal area per plot 15 years ago (maximum (67) F 5 999.9 m2/plot) 76 – 80 Volume per plot 15 years ago (maximum (68) F 5 999.9 m3/plot) 82 Thinning between 15 and 20 years ago (yes (69) I 1 = 1, no = 0) 84 – 88 Basal area per plot 20 years ago (maximum (67) F 5 999.9 m2/plot) 90 – 94 Volume per plot 20 years ago (maximum (68) F 5 999.9 m3/plot) 96 Thinning between 20 and 25 years ago (yes (69) I 1 = 1, no = 0) 98 – 102 Basal area per plot 25 years ago (maximum (67) F 5 999.9 m2/plot) 104 – 108 Volume per plot 25 years ago (maximum (68) F 5 999.9 m3/plot) 110 – 149 Other observations (text) C 40 (177)
Page 30/178 45 Part VI PH
4.4 Part VI Phenological Observations
XX2012.PHE Phenological phenomena (plot level – extensive) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, tree_species, event, date, score, other_observations Column Description Format Ref_Tab Item # 1 –5 Sequence number record (1 to 99999) I 5 7 – 10 Plot number (maximum 9999) I 4 (2) 12 – 14 Tree species I 3 X (42) 16 Event code I 1 X (79) 18 – 23 Date of observation Date (3) 25 - 27 Score of the event C3 X (84) 29 – 68 Other observations (text) C 40 (177)
No more damage assessment on form PHE
XX2009.PLP Form for registration of trees selected for intensive phenological monitoring Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, tree_species, date_installation, tree, visible_part, visible_from, vertical_from, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number record (1 to 99999) I 5 7 – 10 Plot number (maximum 9999) I 4 (2) 12 – 14 Tree species code I 3 X (42) 16 – 21 Installation date in DDMMYY Date (80) 23 – 26 Tree number is the existing identification number C 4 (41) on tree or newly given number preceeded by an M 28 – 29 Codes for visible part crown (during all year): I 2 X (81) 31 Codes for visible direction FROM where the crown I 1 X (82) is observed crown 33 Code for vertical direction from where the I 1 X (83) observations are made
Page 31/178 46 35 – 74 Other observations (text) C 40 (177)
XX2012.PHI Recording of phenological phenomena (tree level – intensive) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, tree, event, date, score, method, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number record (1 to 99999) I 5 7 – 10 Plot number (maximum 9999) I 4 (2) 12 – 15 Tree number C 4 (41) 17 Event code I 1 X (79) 19 – 24 date of the observation Date (3) 26 - 28 score of the event C 3 X (84) 30 Method used for making the observation C 1 X (85) 32– 71 Other observations (text) C 40 (177)
XX2009.PHD Submission of information related to digital images and movies on phenological observations (tree level – intensive) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, tree, tree_species, event, file, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number record (1 to 99999) I 5 7 – 10 Plot number (maximum 9999) I 4 (2) 12 – 15 Tree number C 4 (41) 17 – 19 Tree species code I 3 X (42)
21 – 21 Event code I 1 X (79)
23 – 50 File name of image / movie consisting of C 28 (86) country code, plot number, date of observation, plot and date specific sequence number 52 – 91 other observations C 40 (177)
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XX2012.PHC Submission of information related to control observations (tree level – intensive) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, tree, event, date, score, method, team_ID, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number record (1 to 99999) I 5 7 – 10 Plot number (maximum 9999) I 4 (2) 12 – 15 Tree number („PHE“ in case of plot assessment) C 4 (41) 17 Event code I 1 X (79) 19 – 24 Date of the observation by control team Date (3) 26 - 28 Score of the event by control team C 3 X (84) 30 Method used for making the observation C 1 X (85) 32 – 36 Team_ID I 5 (88) 37 – 76 Other observations (text) C 40 (177)
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Part VII BGV
4.5 Part VII Assessment of Ground Vegetation
XX2012.PLV Contents of reduced plot file to be used in combination with the survey of ground vegetation Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, sample_ID, team_ID, no_members, survey_type, survey_nr, date, latitude, longitude, altitude, fence, sampled_area, tree_cover, shrub_height, shrub_cover, herb_height, herb_cover, mosses_cover, bare_soil_cover, litter_cover, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number of plots (1 to 9999) I 4 6 – 7 Country Code (France = 01, Belgium = 02, etc.) I 2 X (1) 9 – 12 Plot number (max. 9999) I 4 (2) 14 – 15 Sample_ID I 2 (87) 17 – 21 Team ID I 5 (88) 23 Number of Team members I 1 (89) 25 Survey type I 1 X (90) 27 – 28 Survey number (max 99) I 2 (91) 30 – 35 Date of sampling in DDMMYY (e.g. 220690) Date (3) 37 – 43 Latitude in +DDMMSS (e.g.+505852) C 7 (4) 45 – 51 Longitude in (+ or -)DDMMSS (e.g. +035531) C 7 (4) 53 – 54 Altitude (in 50 meter classes from 1 to 51) I 2 X (32) 56 Fence (Yes = 1, No = 2) I 1 X (92) 58 – 61 Total sampled area (in m2) I 4 (93) 63 – 65 Tree layer cover (in % of total area) I 3 (94) 67 – 70 Shrub layer height (in m) F 4 (94) 72 – 75 Shrub layer cover (in % of total area) F 4 (94) 77 – 80 Herb layer height (in m) F 4 (94) 82 – 85 Herb layer cover (in % of total area) F 4 (94) 87 – 90 Mosses cover (in % of total area) F 4 (94) 92 – 95 Bare soil cover (in % of total area) F 4 (94) 97 – 100 Litter cover (in % of total area) F 4 (94) 102 – 141 Other observations (text) C 40 (177)
Page 34/178 49 For covers of shrub, herb, moss bare soil and litter layers: indicate a zero “0” if assessed but not present and leave a blank if not assessed!
XX2012.VEM Contents of datafile with ground vegetation assessments Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, sample_ID, survey_nr, species, layer, substrate, species_cover, certainty, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number of plots (1 to 99999) I 5 7 – 10 Plot number (max. 9999) I 4 (2) 12 – 13 Sample_ID I 2 (87) 15 – 16 Survey number I 2 (91) 18 – 28 Species code (see codelists in Annex) C 11 X (97) 30 Layer (1 = tree, 2 = shrub, 3 = herb, 4 = moss) I 1 X (95) 32 - 33 Substrate I 2 X (96) 35 – 39 Cover of the species in the layer (in %) F 5 (98) 41 Certainty of species determination I 1 X (99) 43 – 82 Other observations (text) C 40 (177)
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Part VIII OZ
4.6 Part VIII Assessment of Ozone Injury
XX2012.PLL OZONE INJURY ASSESSMENT – reduced plot file Special case: In PLL form, it is possible that a country reports that the OTS survey has been conducted, even though that thereare no data reported forthis plot in the OTS file. In such cases, in the PLL it may beindicated that the OTS survey has been carried out, but if no species are reported in the OTS form, this indicatesthat there were no symptomatic species in that plot. Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, survey_tp, latitude, longitude, altitude, rectangles, precision, soil_moisture, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number (1 to 99999) I 5 7 – 8 Country code I 2 X (1) 10 – 13 Plotnumber I 4 (2) 15 – 17 Survey type C 3 X (100) 19 – 25 Latitude (+DDMMSS) C 7 (4) 27 – 33 Longitude (+/-DDMMSS) C 7 (4) Altitude: altitude class code I 2 X (32) 35 – 36 (50m classes from 1-51 ) Total number of rectangles (quadrats) I 2 38 – 39 established*) 41 – 42 Precision level of the sampling (10 or 20, corresponding to 10% or 20% error, see Table I 2 X (103) 4 of submanual) *) (for 2011 onwards only a 10% error is permitted) 41 Soil Moisture within the LESS I 1 X (101) 43 – 82 Other observations (text) C 40 (177) *) only to be reported if survey type is LSS
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XX2004.LTF OZONE INJURY ASSESSMENT – assessment on main tree species (foliar trees) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, tree, tree_species, tree_species_sc_name, sample, date, date_analysis, percentage_symptomatic_actual_c, percentage_symptomatic_cl, validated, validation, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number of plots (1 to 99999) I 5 7 – 8 Country code C 2 X (1) 10 – 13 Plot number I 4 (2) 15 – 18 Tree number (identical to the number in the foliar (152) C 4 X assessment, e.g. F003) 20 – 22 Tree species code I 3 X (42) 24 – 61 Scientific name of tree species C 38 X (42)
63 – 64 Sample number I 2 66 – 71 Date sampling (in DDMMYY) Date (3) 73 – 78 Date analysis (in DDMMYY) Date (3) 80 Percentage of symptomatic leaves for actual year's I 1 X (102) leaves or needles (C). 82 Percentage of symptomatic needles of last year I 1 X (102) (C+1) in code. 84 – 85 Validated (Y/N/NR) C 2 X (104) 87 – 89 Type of validation: The ozone symptom has been C 3 X (105) validated by the validation centre based on code 91 – 130 Other observations (e.g. presence of other biotic or C 40 (177) abiotic factors)
XX2012.LSS OZONE INJURY ASSESSMENT – Less Exposed Sampling Site (LESS) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, rectangle, date, species_sc_name, species, perennial, symptoms, collected_leaves, collected_seeds, validated, validation, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number I 5 7 – 8 Country code I 2 X (1) 10 – 13 Plot number O 4 (2) 15 – 16 Rectangle (quadrat) number I 2 (106)
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Column Description Format Ref_Tab Item # 18 – 23 Date sampling (in DDMMYY) Date (3) 25 – 62 Scientific name (“Empty” in case of empty C 38 X (97) rectangle) 64 – 75 Species code (code of ground vegetation, Flora Europaea; “000.000.000” in case of empty C 12 X (97) rectangle) 77 Perennial/Annual (P/A) C 1 X (187) 77 Ozone symptoms? (Y/N) Y/N 79 Leaves collected (Y/N) Y/N 81 Seeds collected (Y/N) Y/N 83 – 84 Validated (Y/N/NR) C 2 X (104) Type of validation: The ozone symptom has C 3 X 86 – 88 been validated by the validation centre based on (105) code 90 – 129 Other observations (text) C 40 (177)
XX2004.OTS OZONE INJURY ASSESSMENT - OTHER SYMPTOMATIC SPECIES Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, date, species_sc_name, species, perennial woody, validated, validation, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number I 5 7 – 8 Country code I 2 X (1) 10 – 13 Plot number I 4 (2) 15 – 20 Date sampling (in DDMMYY) Date (3) 22 – 59 Scientific name C 38 X (97) 61 – 72 Species code (code of ground vegetation, C 12 X (97) Flora Europaea) 74 Perennial/Annual (P/A) Woody/Non-Woody C 1 X (107) (W/A) 76-77 Validated (Y/N/NR) C 2 X (104) Type of validation: The ozone symptom has 79 – 81 C 3 X (105) been validated by the validation centre. 83-122 Other observations (text) C 40 (177)
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XX2012.OZP OZONE photo documentation Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, date, time, rectangle, photo_file, object_LTF, object_LSS, object_OTS, other_observations Item Column Description Format Ref_Tab # 01 – 04 Sequence number (1 to 9999) I 4 06 – 07 Country code (France = 01, Belgium = 02, etc.) I 2 X (1) 09 – 12 Observation Plot number (maximum 9999) I 4 (2) 14 – 19 Date of field observation (photography) Date (3) 21 – 26 Time of file observation (HHMMSS) (e.g. 095401) C 6 Number of rectangle 28 – 29 I 2 (in case of not being an LSS object submit “-9”) Photo file name in case of photo documentation 31 – 67 C 37 (86) [XXPPPPNNN.NNN.NNN.NDDDDDDTTTTTTSS.jpg] 69 Object is foliar tree (according to form LTF) Y/N 71 Object is part of LESS (according to form LSS) Y/N 73 Object is other species (according to form OTS) Y/N 75 – 114 Other observation (text) C 40 (177)
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Part IX MM
4.7 Part IX Meteorological Measurements
XX2012.PLM Contents of reduced plot file to be used in combination with the meteorological measurements Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, instrument, location, latitude, longitude, altitude,variable,vertical_position, recording, scanning,storing, profile_pit, date_monitoring_1st, date_monitoring_last, measuring_days, instrument_description, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number of plots I 4 6 – 7 Country Code (France = 01, Belgium = 02, etc.) I 2 X (1) 9 – 12 Observation Plot / Corresponding plot I 4 (2) 14 – 16 Instrument number (999) I 3 (108) 18 Location (S = stand, F = open field in forest area, W C 1 (109) = weather station, O = other) X 20 – 26 Latitude in +DDMMSS (e.g.+505852) C 7 (4) 28 – 34 Longitude in (+ or -)DDMMSS (e.g. +035531) C 7 (4) 36 – 37 Altitude (in 50 meter classes from 1 to 51) I 2 X (32) 39 – 40 Variable (AT= air temp, ST = soil temp, PR= C 2 X (110) precipitation, etc.) 42 – 47 Vertical position (in meters above(+) or below F 6 (111) (-) the ground) 49 – 50 Recording code (10 = manual reading, 20 = I 2 X (111) mechanical recording, 30 = paper recording, etc.) 52 – 54 Scanning interval in seconds F 3 (111) (for automatic stations only) 56 – 59 Storing interval in minutes F 4 (111) (for automatic stations only) 61 – 65 Soil Water pit ID. Only submitted for soil moisture C5 (175) measurements 67 – 72 First date of monitoring period Date (140) 74– 79 Final date of monitoring period Date (140) 81– 83 Number of (measuring) days I 3 (141) 85 – 96 Description of instrument C 12 (115) 98– 137 Other observations (text) C 40 (177)
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XX2012.MEM Contents of datafile with meteorological measurements Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, instrument, variable, date, mean_sum min, max, completeness, origin, status, other_observations Column Description Format Ref_Tab Item # 1 – 7 Sequence number of samples I 7 9 – 12 Observation Plot / Corresponding plot I 4 (2) 14 – 16 Instrument number (999) I 3 (108) 18 – 19 Variable code (PR, AT, RH, WS, WD, or SR) C 2 X (110) 21 – 26 Date (in DDMMYY) Date (3) 28 – 33 Daily mean (e.g. temperature) or sum (precipitation) F 6 (110) values 35 – 40 Daily minimum value F 6 (110) 42 – 47 Daily maximum value F 6 (110) 49 – 51 Completeness of measurements over the day (in % of I 3 (112) measurements that should have been recorded) 53 Origin of data I 1 X (113) 55 Status of data I 1 X (114) 57 – 96 Observations (text) C 40 (177)
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XX2012.MEO Contents of datafile with meteorological measurements Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, instrument, variable, date, mean_sum, min, max, completeness, origin, status, other_observations Column Description Format Ref_Tab Item # 1 – 7 Sequence number of samples I 7 9 – 12 Observation Plot / Corresponding plot I 4 (2) 14 – 16 Instrument number I 3 (108) 18 – 19 Variable code (UR, TF, SF, ST, MP, WC, or others) C 2 X (110) 21 – 26 Date (in DDMMYY) Date (3) 28 – 33 Daily mean (e.g. soil temperature) or sum (throughfall) F 6 (110) values 35 – 40 Daily minimum value F 6 (110) 42 – 47 Daily maximum value F 6 (110) 49 – 51 Completeness of measurements over the day (in % of I 3 (112) measurements that should have been recorded) 53 Origin of data; if calculated, method must be specified I 1 X (113) in the DAR 55 Status of data I 1 X (114) 57 – 96 Observations (text) C 40 (177) *) Methods and recomputations that have been used shall be described in detail in an annex to the Data Accompanying Report on meteorology
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XX2012.MEH Contents of datafile with hourly meteorological measurements Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, instrument, variable, date,time_period, mean_sum_H, min_H, max_H, completeness, origin, status, other_observations Column Description Format Ref_Tab Item # 1 – 8 Sequence number of samples I 8 10 – 14 Observation Plot / Corresponding plot I 4 (2) 16 – 17 Instrument number (999) I 3 (108) 19 – 20 Variable code (PR, AT, RH, WS, WD, SR, UR, TF, C 2 X (110) SF, ST, MP, WC) 22 – 27 Date (in DDMMYY) Date (3) 29 – 30 Time period I 2 (166) 32 – 37 Hourly mean (e.g. temperature) or sum (precipitation) F 6 (110) values 39 – 44 Hourly minimum value F 6 (110) 46 – 51 Hourly maximum value F 6 (110) 53 – 55 Completeness of measurements during the respective I 3 (112) hour (in % of measurements that should have been recorded) 57 Origin of data; if calculated, method must be specified I 1 X (113) in the DAR 59 Status of data I 1 X (114) 61 – 100 Observations (text) C 40 (177)
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Part X SO
4.8 Part X Sampling and Analysis of Soil
During the FutMon project we will rely on the BioSoil definitions and recommendations. Concerning the data submission the forms below will be used for data on plots which were not already submitted to the BioSoil data base. Some amendments to BioSoil were made already and highlighted by blue bold font.
XX2012.PLS Contents of reduced plot file Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, date, latitude, longitude, altitude, water, humus, other_observations Column Description Format Ref_Tab Item # l – 4 Sequence number of plots (1 to 9999) I 4 6 – 7 Country Code I 2 X (1) 9 – 12 Plot number (max. 9999) I 4 (2) 14 – 19 Date of sampling in DDMMYY (e.g. Date (3) 220690) 21 – 27 Latitude in +DDMMSS (e.g. + 505852) C 7 (4) 29 – 35 Longitude in (+ or -) DDMMSS (e.g. + C 7 (4) 035531) 37 – 38 Altitude (in 50 meter classes from 1 to 51) I 2 X (32) 40 Water availability I 1 X (30) (insufficient = 1, sufficient = 2, excessive = 3) 42 Humus type ( Mull = 1, Moder = 2, etc.) I 1 X (31) 44 – 83 Other observations C 40 (177)
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XX2009.PFR Soil profile description The information on the WRB soil classification name is not longer part of the PLS file. The same file can be used on Level I and Level II. Mainly based on BioSoil submission forms; amended parameter in blue bold font; Mandatory/Optional also picked from BioSoil; final discussion and definition after submission of the BioSoil database to FutMon data centre and FSCC. Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, profile_pit, date,latitude, longitude, elevation, soil_group, qualifier_1, specifier_1, qualifier_2, specifier_2, qualifier_3, specifier_3, qualifier_4, specifier_4, qualifier_5, specifier_5, qualifier_6, specifier_6, diagnostic_1, diagnostic_depth_1, diagnostic_2, diagnostic_depth_2, diagnostic_3, diagnostic_depth_3, diagnostic_4, diagnostic_depth_4, diagnostic_5, diagnostic_depth_5, diagnostic_6, diagnostic_depth_6, diagnostic_7, diagnostic_depth_7, diagnostic_8, diagnostic_depth_8, diagnostic_9, diagnostic_depth_9, diagnostic_10, diagnostic_depth_10,WRB_publication, parent_material_1, parent_material_2, ground_water_highest, ground_water_lowest, water_table, rooting_depth, rock_depth, obstacle_depth, other_observations Column Description Format Ref_ Item # M/O Tab 1 – 4 Sequence number of plots (1 to 9999) I 4 M 6 – 7 Country code I 2 X (1) M 9 – 12 Observation plot number (maximum 9999) I 4 (2) M 14 – 17 Profile pit ID (maximum 4 characters) C 4 (167) M (same as used in BioSoil) 19 – 24 Date profile description (DDMMYY) Date (3) M 26 – 32 Latitude of profile pit C 7 (4) M (in +DDMMSS) 34 – 40 Longitude of profile pit in C 7 (4) M (+/-DDMMSS) 42 – 45 Elevation of profile pit in metres above sea I 4 O level 47 – 48 Code of WRB Reference Soil Group C 2 X (119) M 50 – 51 WRB Qualifier 1 C 2 X (120) O (1 = most important) 53 – 53 WRB Specifier 1 C 1 X (121) O 55 – 56 WRB Qualifier 2 C 2 X (120) O (2 = second most important,…) 58 – 58 WRB Specifier 2 C 1 X (121) O 60 – 61 WRB Qualifier 3 C 2 X (120) O 63 – 63 WRB Specifier 3 C 1 X (121) O 65 – 66 WRB Qualifier 4 C 2 X (120) O 68 – 68 WRB Specifier 4 C 1 X (121) O 70 – 71 WRB Qualifier 5 C 2 X (120) O 73 – 73 WRB Specifier 5 C 1 X (121) O
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Column Description Format Ref_ Item # M/O Tab 75 – 76 WRB Qualifier 6 C 2 X (120) O 78 – 78 WRB Specifier 6 C 1 X (121) O 80 – 82 Diagnostic 1 C 3 X (122) O 84 – 86 Depth of appearance of diagnostic 1 I 3 (123) O 88 – 90 Diagnostic 2 C 3 X (122) O 92 – 94 Depth diagnostic 2 I 3 (123) O
96 – 98 Diagnostic 3 C 3 X (122) O
100 – 102 Depth diagnostic 3 I 3 (123) O
104 – 106 Diagnostic 4 C 3 X (122) O
108 – 110 Depth diagnostic 4 I 3 (123) O
112 – 114 Diagnostic 5 C 3 X (122) O
116 – 118 Depth diagnostic 5 I 3 (123) O
120 – 122 Diagnostic 6 C 3 X (122) O
124 – 126 Depth diagnostic 6 I 3 (123) O
128 – 130 Diagnostic 7 C 3 X (122) O
132 – 134 Depth diagnostic 7 I 3 (123) O
136 – 138 Diagnostic 8 C 3 X (122) O
140 – 142 Depth diagnostic 8 I 3 (123) O
144 – 146 Diagnostic 9 C 3 X (122) O
148 – 150 Depth diagnostic 9 I 3 (123) O
152 – 154 Diagnostic 10 C 3 X (122) O
156 – 158 Depth diagnostic 10 I 3 (123) O
160 – 163 WRB publication code C 4 X (124) O
165 – 168 Parent Material Code 1 I 4 X (118) M
170 – 173 Parent Material Code 2 I 4 X (118) O
175 – 175 Mean highest ground water level I 1 X (136) M
177 – 177 Mean lowest ground water level I 1 X (136) M
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Column Description Format Ref_ Item # M/O Tab 179 – 179 Type of water table I 1 X (137) M
181 – 183 Effective rooting depth I 3 (138) M (in cm from mineral soil surface) 185 – 187 Rock depth of the soil profile I 3 (138) M if (in cm from mineral soil surface) exist ing 189 – 191 Obstacle depth of the soil profile I 3 (138) M if (in cm from mineral soil surface) exist ing 193 – 232 Other observations (text) C 40 (177) O
XX2009.PFH Soil profile horizons Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, profile_pit, horizon, date_analysis, hor_discontinuity, hor_master, hor_subordinate, hor_vertical, hor_upper, hor_lower, hor_distinctness, hor_topography, structure, colour_moist, colour_dry, hor_texture_class, hor_clay, hor_silt, hor_sand, hor_coarse_vol, hor_coarse_weight, hor_organic_carbon, hor_total_nitrogen, hor_total_CaCO3, hor_gypsum, hor_pH, hor_conductivity, hor_exchange_Ca, hor_exchange_Mg, hor_exchange_K, hor_exchange_Na, hor_exchange_cation_cap, hor_porosity, hor_bulk_density_measure, hor_bulk_density_estimate, roots_very_fine, roots_fine, roots_medium, roots_coarse,other_observations Column Description Format Ref_Tab Item # M/O 1 – 4 Sequence number (maximum 9999) I 4 M 6 – 7 Country code I 2 X (1) M 9 – 12 Observation plot number I 4 (2) M (maximum 9999) 14 – 17 Profile pit ID (maximum 4 characters) C 4 (174) M (same as used in BioSoil) 19 – 20 Horizon number I 2 (128) M 22 – 27 Date laboratory analysis (DDMMYY) Date (3) M 29 Horizon discontinuity I 1 X (129) M if exists 31 – 33 Horizon master C 3 X (129) M 35 – 38 Horizon subordinate C 4 X (129) M if exists 40 Horizon vertical I 1 (129) M if exists
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42 – 44 Upper horizon limit (in cm) I 3 (130) M 46 – 48 Lower horizon limit (in cm) I 3 (130) M 50 Horizon distinctness I 1 X (131) O 52 Horizon topography I 1 X (132) O 54 – 55 Structure I 2 X (133) M for mineral hor. 57 – 69 Moist colour of the soil matrix (Munsell C 13 M for soil colour charts) mineral hor. 71 – 83 Dry colour of the soil matrix (Munsell C 13 M for soil colour charts) mineral hor. 85 –88 Horizon Textural class C 4 X (116) M for mineral hor. 90–93 Horizon Clay (0 – 2 micrometer fraction) F 4 M for (%) mineral hor. 95 – 98 Horizon Silt (2 – 63 micrometer fraction) F 4 M for (%) mineral hor. 100–103 Horizon Sand (63 – 2000 micrometer F 4 M for fraction) (%) mineral hor. 105 Horizon code coarse fragments (code I 1 X (134) M for based on volume %) mineral hor. 107– 109 Horizon coarse fragments (weight % in I 3 O for g/100g) mineral hor. 111 – 115 Horizon Total Organic Carbon content F 5 M (g/kg) 117 – 121 Horizon Total Nitrogen (g/kg) F 5 M 123 – 125 Horizon Total Calcium Carbonate (g/kg) F 3 M if present 127 – 129 Horizon Gypsum content (g/kg) F 3 O 131 – 134 Horizon pH F 4 M 136 – 139 Horizon Electrical conductivity (dS.m-1) F 4 O 141 – 146 Horizon Exchangeable Ca (cmol(+)/kg) F 6 M 148 – 153 Horizon Exchangeable Mg (cmol(+)/kg) F 6 M 155 – 160 Horizon Exchangeable K (cmol(+)/kg) F 6 M 162 – 167 Horizon Exchangeable Na (cmol(+)/kg) F 6 M
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169 – 174 Horizon Cation Exchange Capacity F 6 M for (cmol(+)/kg) mineral hor. 176 Horizon Code Porosity I 1 X (135) M 178 – 181 Horizon Measured Bulk Density (in F 4 M kg/m3) 183 – 186 Horizon Estimated Bulk Density (in F 4 M if not kg/m3) measur ed 188 Very fine roots: abundance class I 1 X (138) O 190 Fine roots: abundance class I 1 X (138) O 192 Medium roots: abundance class I 1 X (138) O 194 Coarse roots: abundance class I 1 X (138) O 196 – 245 Other observations C 50 (177) O
XX2009.SOM Contents of datafile with soil analysis information (Mandatory and optional as required by the BioSoil project) Level I + Level II
Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, layer, repetition, layer_superior, layer_inferior, subsamples, date_analysis, moisture_content, clay, silt, sand, texture, bulk_density_dry_fine_earth, coarse_fragments_vol, organic_layer_dry_weight, pH_CaCl, pH_H2O, total_organic_carbon, total_nitrogen, carbonates, exchange_acidity, exchange_Al, exchange_Ca, exchange_Fe, exchange_K, exchange_Mg, exchange_Mn, exchange_Na, Free_H_acidity, extract_Al, extract_Ca, extract_Cd, extract_Cr, extract_Cu, extract_Fe, extract_Hg, extract_K, extract_Mg, extract_Mn, extract_Na, extract_Ni, extract_P, extract_Pb, extract_S, extract_Zn, total_Al, total_Ca, total_Fe, total_K, total_Mg, total_Mn, total_Na, reactive_Al, reactive_Fe, other_observations Item Column Description Format Ref_Tab # 1 – 5 Sequence number I 5 7 – 8 Country code I 2 X (1) 10 – 13 Observation plot number I 4 (2) 15 – 17 Code layer C 3 X (117) 19 – 20 Repetition I 2 (125) 22 – 25 Layer limit superior F 4 (126) 27 – 30 Layer limit inferior F 4 (126) 32 – 33 Subsamples (N° in the composite) I 2 (127) Date laboratory analysis (DDMMYY) of most 35 – 40 Date (3) recent analysis on the concerning sample Moisture content 42 – 45 F 4 (difference between air dry and oven dry moisture)
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Item Column Description Format Ref_Tab # in % 47 – 50 Clay (0 – 2 micrometer fraction) (%) F 4 52 – 55 Silt (2 – 63 micrometer fraction) (%) F 4 57 – 60 Sand (63 – 2000 micrometer fraction) (%) F 4 62 – 65 Texture class C 4 X (116) 67 – 70 Mean dry bulk density of the fine earth in kg/m3 F 4 72 – 74 Volume coarse fragments (volume %) I 3 76 – 80 Total dry weight of the organic layer (kg/m2) F 5
82 – 85 pH(CaCl2) F 4
87 – 90 pH(H2O) F 4 92 – 96 Total Organic Carbon (g/kg) F 5 98 – 102 Total Nitrogen (g/kg) F 5
104 – 106 Carbonates (g/kgCa_CO3) F 3 108 – 113 Exchangeable acidity (cmol(+)/kg) F 6 115 – 120 Exchangeable Al (cmol(+)/kg) F 6 122 – 127 Exchangeable Ca (cmol(+)/kg) F 6 129 – 134 Exchangeable Fe (cmol(+)/kg) F 6 136 – 141 Exchangeable K (cmol(+)/kg) F 6 143 – 148 Exchangeable Mg (cmol(+)/kg) F 6 150 – 155 Exchangeable Mn (cmol(+)/kg) F 6 157 – 162 Exchangeable Na (cmol(+)/kg) F 6 164 – 169 Free H+ acidity (cmol(+)/kg) F 6 171 – 178 Extractable Al (mg/kg) F 8 180 – 187 Extractable Ca (mg/kg) F 8 189 – 192 Extractable Cd (mg/kg) F 4 194 – 198 Extractable Cr (mg/kg) F 5 200 – 206 Extractable Cu (mg/kg) F 7 208 – 215 Extractable Fe (mg/kg) F 8 217 – 222 Extractable Hg (mg/kg) F 6 224 – 230 Extractable K (mg/kg) F 7 232 – 239 Extractable Mg (mg/kg) F 8 241 – 247 Extractable Mn (mg/kg) F 7 249 – 254 Extractable Na (mg/kg) F 6 256 – 260 Extractable Ni (mg/kg) F 5 262 – 267 Extractable P (mg/kg) F 6 269 – 274 Extractable Pb (mg/kg) F 6 276 – 281 Extractable S (mg/kg) F 6 283 – 288 Extractable Zn (mg/kg) F 6 290 – 297 Total Al (mg/kg) F 8 299 – 306 Total Ca (mg/kg) F 8 308 – 315 Total Fe (mg/kg) F 8 317 – 324 Total K (mg/kg) F 8 326 – 333 Total Mg (mg/kg) F 8 335 – 342 Total Mn (mg/kg) F 8 344 – 351 Total Na (mg/kg) F 8 Reactive Al (acid oxalate extractable Al) 353 – 359 F 7 (mg/kg)
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Item Column Description Format Ref_Tab # Reactive Fe (acid oxalate extractable Fe) 361 – 367 F 7 (mg/kg) 369 – 418 Other observations C 50 (177)
Methods and recomputations that have been used shall be described in detail in the Data Accompanying Report.
XX2009SO.LQA Soil analysis – Laboratory QA/QC information Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, date_start, date_end, parameter, extraction, sieving, removal_compounds, determination, quantification_limit, control_chart_mean, control_chart_std, ring_test_participation, ring_test_number, Laboratory_ID, percentage_within, requalification, percentage_within_requal, other_observations
Column Description Format Ref_Tab Item #
01 – 04 Sequence number (1 to 9999) I 4 06 – 07 Country code (France = 01, Belgium = 02, etc.) I 2 X (1) 09 – 12 Observation Plot number (maximum 9999) I 4 (2) 14 – 19 start date Date (188) 21 – 26 end date Date (188) 28 – 36 Parameter Code* (N, S, Ca etc.) C 9 X (185) 38 – 41 Digestion/Extraction method (pretreatment) C 4 X (178) 43 – 45 Sieving/milling method F 3 X (187) 47 – 49 code removal compounds F 3 X (186) 51 – 54 Determination method (see reference list) F 4 X (179) 56 – 61 Quantification limit (unit of parameter) F 6 (180) 63 – 68 Mean of control chart F 6 (180) 70 – 72 Relative standard deviation [%] F3 (180) 74 Participated at ring Test (yes = 1, no = 0) I 1 (180) 76 – 78 ICP Forests Ring Test Number C 3 (180) 80 – 82 ID of laboratory (e.g. H45, B78, etc.) C 3 (180) Percentage [%] of the results of the ring tests 84 – 86 I 3 (180) within tolerable limits for each ring test 88 Requalification information (yes = 1, no = 0) I 1 (180) Percentage [%] of the results of the ring tests 90 – 92 within tolerable limits for each ring test in I 3 (180) requalification
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Column Description Format Ref_Tab Item #
94 – 133 Other observations (freetext) C 40 (177)
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Part XI SS
4.9 Part XI Soil Solution Collection and Analysis
XX2012.PSS Contents of reduced plot file to be used in combination with the soil solution measurements Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, latitude, longitude, altitude, sampler_ID, sampler_type, layer, depth, samplers, date_monitoring_1st, date_monitoring_last, periods, other_observations Item Column Description Format Ref_Tab # 1 – 4 Sequence number of plots (1 to 9999) I 4 6 – 7 Country Code (France = 01, Belgium = 02, etc.) I 2 X (1) 9 – 12 Observation plot number I 4 (2) 14 – 20 Latitude in +DDMMSS (e.g.+505852) C 7 (4) 22 – 28 Longitude in (+ or -)DDMMSS (e.g. +035531) C 7 (4) 30 – 31 Altitude (in 50 meter classes from 1 to 51) I 2 X (32) 33 – 35 Sampler_IDNumber (1 – 999) I 3 (143) 37 Sampler Type (1 = Tension lysimeter, 2 = Zero I 1 X (146) tension lysimeter, 3 = Centrifugation, 4 = Saturation extraction) 39 Layer (H, O = Organic, M = Mineral) C 1 X (145) 41 – 45 Sampling depth (in meters below surface) F 5 (147) 47 – 48 N of samplers (number of used samplers) I 2 (148) 50 – 55 1st period start date (DDMMYY) Date (140) 57 – 62 last period final date (DDMMYY) Date (140) 64– 65 Number of (equal) monitoring periods I 2 (141) 67– 106 Other observations (text) C 40 (177)
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XX2012.SSM Contents of datafile with soil solution measurements (mandatory) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, sampler_ID, sample_ID, date_start, date_end, period, sample_vol, pH, conductivity, K, Ca, Mg, N_NO3, S_SO4, alkalinity, Al, DOC,Na,N_NH4,Cl,Tot_N,Fe,Mn, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number of samples (1 to 99999) I 5 7 – 10 Observation plot number (max. 9999) I 4 (2) 12 – 14 Sampler_ID I 3 (143) 16 – 19 Sample_ID I 4 (144) 21 – 26 Start date (DDMMYY) Date (3) 28 – 33 End date (DDMMYY) Date (3) 35 – 36 Period number (max. 99) I 2 (142) 38 – 42 Volume per sample [ml] F 5 (149) 44 – 46 pH F 3 48 – 51 Conductivity (S/cm) F 4 53 – 57 K (mg/L) F 5 59 – 63 Ca (mg/L) F 5 65 – 69 Mg (mg/L) F 5
71 – 75 N-NO3 (mg/L) F 5
77 – 81 S-SO4 (mg/L) F 5 83 – 86 Alkalinity (µmolc/L) F 4 88 – 92 Al**) (mg/L) F 5 94 – 98 DOC (mg/L) F 5 100 – 104 Na (mg/L) F 5
106 – 110 N-NH4 (mg/L) F 5 112 – 116 Cl (mg/L) F 5 118 – 122 Total N (mg/L) F 5 124 – 128 Fe (mg/L) F 5 130 – 134 Mn (mg/L) F 5 136 – 175 Observation Text C 40 (177) Methods and recomputations that have been used shall be described in detail in an annex to the Data Accompanying Report on soil solution. **) Mandatory if pH<5
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XX2012.SSO Contents of datafile with soil solution measurements (Optional) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, sampler_ID, sample_ID, date_start, date_end, period,water_vol, Na, Al_labile, Fe, Mn, P, N_NH4, Cl, Cr, Ni, Zn, Cu, Pb, Cd, Si, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number of samples (1 to 99999) I 5 7 – 10 Corresponding plot number (max. (2) I 4 9999) 12 - 14 Sampler_ID I 3 (143) 16 – 19 Sample_ID I 4 (144) 21 – 26 Start date (DDMMYY) Date (3) 28 – 33 End date (DDMMYY) Date (3) 35 – 36 Period number (max. 99) I 2 (142) 32 – 35 Water content (extraction only) F 4 (cm3/cm3) 37 – 41 Na (mg/L) F 5 38 – 42 Al-labile (mg/L) F 5 49 – 53 Fe (mg/L) F5 55 – 59 Mn (mg/L) F 5 44 – 48 P (mg/L) F 5
67 – 71 N-NH4 (mg/L) F 5 73 – 77 Cl (mg/L) F 5 50 – 54 Cr (µg/L) F 5 56 – 60 Ni (µg/L) F 5 62 – 65 Zn (µg/L) F 4 67 – 70 Cu (µg/L) F 4 72 – 75 Pb (µg/L) F 4 77 – 81 Cd (µg/L) F 5 83 – 87 Si (mg/L) F 5 89 – 128 Observations Text C 40 (177) Methods and recomputations that have been used shall be described in detail in an annex to the Data Accompanying Report on soil solution.
XX2009SS.LQA Soil Solution – Laboratory QA/QC information Each data file has to start with a comment line. This line starts with an exclamation mark:
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!Sequence, country, plot, date_start, date_end, parameter, determination, quantification_limit, control_chart_mean, control_chart_std, ring_test_participation, ring_test_number, Laboratory_ID, percentage_within, requalification, percentage_within_requal, other_observations Column Description Format Ref_Tab Item # 01 – 04 Sequence number (1 to 9999) I 4 06 – 07 Country code (France = 01, Belgium = 02, etc.) I 2 X (1) 09 – 12 Observation Plot number (maximum 9999) I 4 (2) 14 – 19 start date Date (188) 21 – 26 end date Date (188) 28 – 36 Parameter Code (Ca, Mg, etc.) C 9 X (182) 38 – 41 Determination method (see reference list) F 4 X (179) 43 – 48 Quantification limit (unit of parameter) F 6 50 – 55 Mean of control chart F 6 (180) 57 – 59 Relative Standard Deviation [%] F 3 (180) 61 Participated at ring Test (yes = 1, no = 0) I 1 (180) 63 – 65 ICP Forests Ring Test Number C 3 (180) 67 – 69 ID of laboratory (e.g. H45, B78, etc.) C 3 (180) Percentage [%] of the results of the ring tests (180) 71 – 73 I 3 within tolerable limits for each ring test 75 Requalification information (yes = 1, no = 0) I 1 (180) Percentage [%] of the results of the ring tests (180) 77 – 79 within tolerable limits for each ring test in I 3 requalification 81 – 120 Other observations (freetext) C 40 (177)
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Part XII FO
4.10 Part XII Sampling and Analysis of Needles and Leaves
XX2005.PLF Contents of reduced plot fileto be used in combination with the survey of chemical contentof needles and leaves Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, date, latitude, longitude, altitude, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number of plots (1 to 9999) I 4 6 – 7 Country Code (France = 01, Belgium = 02, etc.) I 2 X (1) 9 – 12 Plotnumber (max. 9999) I 4 (2) 14 – 19 Date of sampling in DDMMYY (e.g. 220690) Date (3) 21 – 27 Latitude in +DDMMSS (e.g.+505852) C 7 (4) 29 – 35 Longitude in (+ or -)DDMMSS (e.g. +035531) C 7 (4) 37 – 38 Altitude (in 50 meter classes from 1 to 51) I 2 X (32) 40 – 79 Other observations (text) C 40 (177)
XX2012.FOT Tree Numbers of trees from which samples were taken !Sequence, plot, sample_ID,tree,tree_species, leaves_type, foliage_age_classes, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence Number (1 to 99999) I 5 7 – 10 Observation Plot number (max. 9999) I 4 (2) 12 – 13 Sample_ID I 2 (151) 15 - 18 Tree number (e.g. F201) C 4 (152) 20 – 22 Tree species I 3 X (42) 24 leaves type (0 = current, 1 = current + 1, 2 = older than current + 1, 3 as I 1 X (150) combination of codes 1 and 2) 26 – 27 Number of foliage age I 2 (153) classes 29 – 68 other observations (text) C 40 (177)
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XX2012.FOM Contents of file with foliar analysis information (mandatory) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, sample_ID, date_start, date_end, tree_1_6, tree_2_7, tree_3_8, tree4_9, tree_5_10, mass_leaves, mass_needles, N, S, P, Ca, Mg, K, C, Zn, Mn, Fe, Cu, Pb, Cd, B, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence Number(1 to 99999) I 5 7 – 10 Observation Plot number (max. 9999) I 4 (2) 12 – 13 Sample ID I 2 (151) 15 – 20 Start date of analysis (ddmmyy) Date (3) 22–27 End date of analysis (ddmmyy) Date (3) 25 – 28 Number of first tree in sample C 4 (152) 30 – 33 Number of second tree in sample C 4 (152) 35 – 38 Number of third tree in sample C 4 (152) 40 – 43 Number of fourth tree in sample C 4 (152) 45 – 48 Number of fifth tree in sample C 4 (152) 29 – 32 Mass of 100 leaves. Dry mass of 100 F 4 (154) current year leaves [g] 34 – 37 Mass of 1000 needles Dry mass of 1000 current year or 1000 F 4 (154) current+1 year needles or 1000 needles older than current+1 year[g] By reference at 105° dried material: 39 – 43 N mg/g F 5 45 – 49 S mg/g F 5 51 – 54 P mg/g F 4 56 – 60 Ca mg/g F 5 62 – 66 Mg mg/g F 5 68 – 72 K mg/g F 5 74 – 78 C g/100g F 5 80 – 84 Zn µg/g F 5 86 – 91 Mn µg/g F 6 93 – 97 Fe µg/g F 5 99 – 103 Cu µg/g F 5 105 – 109 Pb µg/g F 5 Page 58/178 73
Column Description Format Ref_Tab Item # 111– 115 Cd ng/g F 5 117 – 121 B µg/g F 5 123 – 162 other observations (text) C 40 (177)
XX2011.FOO Contents of file with foliar analysis information (optional) former FOO has been merged with FOM
XX2009FO.LQA Foliar analysis – Laboratory QA/QC information Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, date_start, date_end, parameter, pretreatment, determination, quantification_limit, control_chart_mean, control_chart_std, ring_test_participation, ring_test_number, Laboratory_ID, percentage_within, requalification, percentage_within_requal, other_observations Column Description Format Ref_Tab Item # 01 – 04 Sequence number (1 to 9999) I 4 06 – 07 Country code (France = 01, Belgium = 02, etc.) I 2 X (1) 09 – 12 Observation Plot number (maximum 9999) I 4 (2) 14 – 19 start date Date (188) 21 – 26 end date Date (188) 28 – 29 Parameter Code (N, S, Ca etc.) C 2 X (181) 31 – 34 Pretreatment method (see reference list) F 4 X (178) 36 – 39 Determination method (see reference list) F 4 X (179) 41 – 46 Quantification limit (unit of parameter) F 6 (180) 48 – 53 Mean of control chart F 6 (180) 55 – 57 Relative Standard Deviation [%] F 3 (180) 59 Participated at ring Test (yes = 1, no = 0) I 1 (180) 61 – 63 ICP Forests Ring Test Number C 3 (180) 65 – 67 ID of laboratory (e.g. H45, B78, etc.) C 3 (180) Percentage [%] of the results of the ring tests 69 – 71 I 3 (180) within tolerable limits for each ring test 73 Requalification information (yes = 1, no = 0) I 1 (180) Percentage [%] of the results of the ring tests 75 – 77 within tolerable limits for each ring test in I 3 (180) requalification 79 – 118 Other observations (text) C 40 (177)
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Part XIII LF
4.11 Part XIII Sampling and Analysis of Litterfall
XX1996.LFP Contents of reduced plot file to be used in combination with the survey on litterfall Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, latitude, longitude, altitude, traps, collecting_area, date_monitoring_1st, date_monitoring_last, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number of plots (1 to 9999) I 4 Country Code (France = 01, Belgium = 02, I 2 X (1) 6 – 7 etc.) 9 – 12 Plotnumber (max. 9999) I 4 (2) 14 – 20 Latitude in +DDMMSS (e.g.+505852) C 7 (4) Longitude in (+ or -)DDMMSS (e.g. C 7 (4) 22 – 28 +035531) 30 – 31 Altitude (in 50 meter classes from 1 to 51) I 2 X (32) 33 – 34 Number of traps I 2 36 – 39 Total Collecting area (in m2) F 4 Active sampling period (from) in Date (140) 41 – 46 DDMMYY (e.g. 010690) Date Active sampling period (till) in DDMMYY (140) 48 – 53 (e.g. 300690) 55 – 94 Other observations (text) C 40 (177)
XX2012.LFM Contents of data file with litterfall analysis information (mandatory)
Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot,date_start_collect, date_end_collect,date_start_ana, date_end_ana, trap,pooling,tree_species, sample, dry_weight, dry_mass, area, N, S, P, Ca, Mg, K, C, Zn, Mn, Fe, Cu, Pb, Cd, B,other_observations
Item Column Description Format Ref_Tab # 1 – 5 Sequence Number (1 to 99999) I 5
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Item Column Description Format Ref_Tab # 7 – 10 Observation Plot number (max. 9999) I 4 (2) 12 – 17 Collection period (from) Date (3) 19 – 24 Collection period (till) Date (3) 26 – 31 Start date of analysis (ddmmyy) Date (3) 33 –38 End date of analysis (ddmmyy) Date (3) 40 – 41 Trap number: "-9" means plot average I 2 (155) 43 Pooled periods (Y/N) Y/N Tree species: dominant or co-dominant species I 3 X (42) 45 – 47 (code) (in case of “all species” use 888) 49 – 52 Sample code F 4 X (156) 54 – 59 Dry weight per m2 [kg/m2] F 6 61 – 64 Dry mass of 100 leaves or of 1000 needles [g] F 4 (154) 66 – 69 Area of 100 leaves or of 1000 needles [m2] F 4 (154) Parameters Units **) C shifted to columns 92-102 – same order as in
FOM 71 – 75 N [mg/g] F 5 77 – 81 S [mg/g] F 5 83 – 86 P [mg/g] F 4 88 – 92 Ca [mg/g] F 5 94 – 98 Mg [mg/g] F 5 100 – 104 K [mg/g] F 5 106 – 110 C [g/100g] F 5 112 – 116 Zn [μg/g] F 5 118 – 123 Mn [μg/g] F 6 125 – 129 Fe [μg/g] F 5 131 – 136 Cu [μg/g] F 6 138 – 142 Pb [μg/g] F 5 144 – 148 Cd [ng/g] F 5 150 – 154 B [μg/g] F 5 156 – 195 Other observations text C 40 (177) **) By reference at 105° dried material
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XX2009LF.LQA Litterfall – Laboratory QA/QC information Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, date_start, date_end, parameter, pretreatment, determination, quantification_limit, control_chart_mean, control_chart_std, ring_test_participation, ring_test_number, Laboratory_ID, percentage_within, requalification, percentage_within_requal, other_observations Column Description Format Ref_Tab Item # 01 – 04 Sequence number (1 to 9999) I 4 06 – 07 Country code (France = 01, Belgium = 02, etc.) I 2 X (1) 09 – 12 Observation Plot number (maximum 9999) I 4 (2) 14 – 19 start date Date (188) 21 – 26 end date Date (188) 28 – 29 Parameter Code (C, N, etc.) C 2 X (184) 31 – 34 Pretreatment method (see reference list) F 4 X (178) 36 – 39 Determination method (see reference list) F 4 X (179) 41 – 46 Quantification limit (unit of parameter) F 6 (180) 48 – 53 Mean of control chart F 6 (180) 55 – 57 Relative Standard Deviation [%] F 3 (180) 59 Participated at ring Test (yes = 1, no = 0) I 1 (180) 61 – 63 ICP Forests Ring Test Number C 3 (180) 65 – 67 ID of laboratory (e.g. H45, B78, etc.) C 3 (180) Percentage [%] of the results of the ring tests (180) 69 – 71 I 3 within tolerable limits for each ring test 73 Requalification information (yes = 1, no = 0) I 1 (180) Percentage [%] of the results of the ring tests (180) 75 – 77 within tolerable limits for each ring test in I 3 requalification 79 – 118 Other observations (freetext) C 40 (177)
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Part XIV DP
4.12 Part XIV Sampling and Analysis of Deposition
XX2012.PLD Contents of reduced plot file to be used in combination with the deposition measurements Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, sampler,sampler_ID,latitude, longitude, altitude, date_monitoring_1st, date_monitoring_last, periods, sampler_model, sampler_height, sampler_surface, samplers, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number of plots (1 to 9999) I 4 6 – 7 Country Code (France = 01, Belgium = 02, etc.) I 2 X (1) 9 – 12 Observation plot number I 4 (2) 14 Sampler type code I 1 X (157) 16 – 18 Sampler_ID I 3 (158) 20 – 26 Latitude in +DDMMSS (e.g.+505852) C 7 (4) 28 – 34 Longitude in (+ or -)DDMMSS (e.g. +035531) C 7 (4) 36 – 37 Altitude (in 50 meter classes from 1 to 51) I 2 X (32) 39 – 44 First date of monitoring period Date (140) 46 – 51 Final date of monitoring period Date (140) 53 – 54 Number of (equal) measuring periods I 2 (141) Sampler model 56 I 1 X (160) (1=national sampler, 2=harmonised samplers) 58 – 61 Sampler Height [m] F 4 (161) 63 – 67 Sampler Surface [m²] F 5 (162) 69 – 70 N of samplers (number of used samplers) I 2 (163) 72 – 111 Other observations (text) C 40 (177)
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XX2012.DEM Contents of datafile with deposition measurements (mandatory) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, date_start, date_end, period, sampler,sampler_ID,sample_ID, V_sampling, quantity, pH, conductivity, K, Ca, Mg, Na, N_NH4, Cl, N_NO3, S_SO4, alkalinity, N_total, DOC, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number of samples (1 to 99999) I 5 7 – 10 Observation Plot number (max.9999) I 4 (2) 12 – 17 Start date (DDMMYY) Date (3) 19 – 24 End date (DDMMYY) Date (3) 26 – 27 Period number (max. 99) I 2 (142) 29 Sampler type code I 1 X (157) 31- 33 Sampler_ID I 3 (158) 35 – 38 Sample_ID I 4 (159) 40 V_sampling I 1 X (164)
42 – 45 Quantity of the total collected sample expressed in mm F 4 (165) 47 – 49 pH F 3 51 – 54 Conductivity (µS/cm) F 4 56 – 59 K (mg/L) F 4 61 – 65 Ca (mg/L) F 5 67 – 70 Mg (mg/L) F 4 72 – 76 Na (mg/L) F 5
78 – 82 N-NH4 (mg/L) F 5 84 – 88 Cl (mg/L) F 5
90 – 94 N-NO3 (mg/L) F 5
96 – 100 S-SO4 (mg/L) F 5 102 – 105 Alkalinity (µeq/L) F 4 107 – 111 N (total) (mg/L) F 5 113 – 117 DOC (Dissolved organic carbon) (mg/L) F 5 119 – 158 Observation text (e.g. orientation , liming ...) C 40 (177) *) Methods and recomputations that have been used shall be described in detail in an annex to the deposition report.
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XX2012.DEO Contents of datafile with deposition measurements (Optional) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, date_start, date_end, period, sampler, sampler_ID,sample_ID, V_sampling, quantity, Al, Mn, Fe, P_PO4, Cu, Zn, Hg, Pb, Co, Mo, Ni, Cd, S_total, C_total, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence number of samples (1 to 99999) I 5 7 – 10 Observation Plot number (max.9999) I 4 (2) 12 – 17 Start date (DDMMYY) Date (3) 19 – 24 End date (DDMMYY) Date (3) 26 – 27 Period number (max. 99) I 2 (142) 29 Sampler type code I 1 X (157) 31 – 33 Sampler_ID I 3 (158) 35 – 38 Sample_ID I 4 (159) 40 V_sampling I 1 X (164) 42 – 45 Quantity of the total collected sample expressed in (165)
mm (max. 9999) F 4 47 – 50 Al3+ (µg/L) F 4 52 – 56 Mn2+(µg/L) F 5 58 – 62 Fe3+(µg/L) F 5 3- 64 – 67 P-PO4 (mg/L) F 4 69 – 72 Cu (µg/L) F 4 74 – 77 Zn (µg/L) F 4 79 – 82 Hg (µg/L) F 4 84 – 87 Pb (µg/L) F 4 89 – 92 Co (µg/L) F 4 94 – 97 Mo (µg/L) F 4 99 – 102 Ni (µg/L) F 4 104 – 107 Cd (µg/L) F 4
109 – 113 Stotal (mg/L) F 5
115 – 118 Ctotal (mg/L) F 4 120 – 159 Observation text (e.g. orientation, liming ...) F 40 (177) *) Methods and recomputations that have been used shall be described in detail in an annex to the deposition report
XX2009DP.LQA Deposition – Laboratory QA/QC information Each data file has to start with a comment line. This line starts with an exclamation mark:
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!Sequence, country, plot, date_start, date_end, parameter, pretreatment, determination, quantification_limit, control_chart_mean, control_chart_std, ring_test_participation, ring_test_number, Laboratory_ID, percentage_within, requalification, percentage_within_requal, other_observations Column Description Format Ref_Tab Item # 01 – 04 Sequence number (1 to 9999) I 4 06 – 07 Country code (France = 01, Belgium = 02, etc.) I 2 X (1) 09 – 12 Observation Plot number (maximum 9999) I 4 (2) 14 – 19 start date Date (188) 21 – 26 end date Date (188) 28 – 34 Parameter Code (K, Ca, etc.) C 7 X (183) 36 – 39 Pretreatment method (see reference list) F 4 X (178) 41 – 44 Determination method (see reference list) F 4 X (179) 46 – 51 Quantification limit (unit of parameter) F 6 (180) 53 – 58 Mean of control chart F 6 (180) 60 – 62 Relative Standard Deviation [%] F 3 (180) 64 Participated at ring Test (yes = 1, no = 0) I 1 (180) 66 – 68 ICP Forests Ring Test Number C 3 (180) 70 – 72 ID of laboratory (e.g. H45, B78, etc.) C 3 (180) Percentage [%] of the results of the ring tests 74 – 76 I 3 (180) within tolerable limits for each ring test 78 Requalification information (yes = 1, no = 0) I 1 (180) Percentage [%] of the results of the ring tests 80 – 82 within tolerable limits for each ring test in I 3 (180) requalification 84 – 123 Other observations (freetext) C 40 (177)
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Part XV AQ
4.13 Part XV Monitoring of Air Quality
XX2009.PAC Form with plot info on the station with the active sampler(s) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, latitude, longitude, altitude,compound, sampler, inlet_height, date_monitoring_1st, hour_start, date_monitoring_last, hour_end, col, altitude_m, elevation_lowest2500, elevation_lowest5000, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number I 4 6 – 7 Country code (France = 01, etc.) I 2 X (1) 9 – 12 Plot number I 4 (2) 14 – 20 Latitude in +DDMMSS C 7 (4) 22 – 28 Longitude in (+ or -) DDMMSS C 7 (4) 30 – 31 Altitude (in 50 m classes 1-51) I 2 X (32) 33 – 35 Compound air quality C 3 X (167) 37 – 38 Sampler ID I 2 (169) 40 – 43 Inlet height (in m with accuracy 0.1m) F 4 45 – 50 Start date measurements (DDMMYY) Date (140) Start hour (HH) (First Hour of measurement 52 – 53 I 2 (166) period) 55 – 60 End date measurements (DDMMYY) Date (140) End hour (HH) (Last Hour of sampling 62 – 63 period) I 2 (166)
Continuous analyzers co-located with 65-65 Y/N (172) passive samplers (Y/N) 67-70 Altitude (in m)* I 4 Lowest elevation in a circular area of 2.5 km 72-75 I 4 (173) radius* (in 9999 m) Lowest elevation in a circular area of 5.0 km 77-80 I 4 (173) radius* (in 9999 m) 82 – 121 Other observations (text) C 40 (177) *Only for ozone measurements Note: For continuous analyzers: If for a given pollutant and plot measurements are taken with more than one continuous analyzer, identify them with a different sampler_ID (e.g. with
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XX2012.PPS Form with information on passive sampler(s) on intensive monitoring plot and at stations Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot,latitude longitude altitude, compound, sampler,manufacturer, date_monitoring_1st, date_monitoring_last, measurements, col, altitude_m elevation_lowest2500 elevation_lowest5000, sampling_height, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number I 4 6 – 7 Country code (France = 01, etc.) I 2 X (1) I 4 9 – 12 Observation plot number (2)
14 – 20 Latitude in +DDMMSS C 7 (4) 22 – 28 Longitude in (+ or -) DDMMSS C 7 (4) 30 – 31 Altitude (in 50 m classes 1-51) I 2 X (32) 33 – 35 Compound air quality C 3 X (167) 37 – 38 Sampler ID I 2 (169) 40–41 Passive sampler manufacturer I 2 X (170) 43–48 Start date measurements (DDMMYY) Date (140) 50–55 End date measurements (DDMMYY) Date (140) Number of measurements with passive sampler 57–58 I 2 (99) Passive sampler co-located with continuous 60–60 Y/N (172) analyzers (Y/N) 62–65 Altitude (in m)* I 4 Lowest elevation in a circular area of 2.5 km 67–70 I 4 (173) radius* (in 9999 m) Lowest elevation in a circular area of 5.0 km 72–75 I 4 (173) radius* (in 9999 m) Sampling height; standardized at 2 meters(in 77 – 80 m; accuracy 0.01m; e.g submit "2.15" for F 4 2meters and 15 centimeters) 82 – 121 Observations C 40 (177)
*Only for ozone measurements Note: If for a given pollutant and plot measurements are taken with more than one passive sampler, identify them with a different sampler_ID (e.g. with succesive numbers: 01, 02, 03, ...)Note that each passive sampler has a unique code. This is Country code – plotnumber – sampler ID
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.XX2009.AQA data file to be used for data from active samplers Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, sampler, date, hour, O3, SO2, NO2, NH3, other_observations Column Description Format Ref_Tab Item # 1 – 6 Sequence number I 6 8 – 9 Country code (France = 01, etc.) I 2 X (1) 11 – 14 Plot number I 4 (2) 16 – 17 Sampler ID I 2 (169) 19 – 24 Date (DDMMYY) Date (3) 26 – 27 Hour (HH) (hour of measurement data) I 2 (166) 29 – 34 Hourly O3 concentration (ppb) F 6 (171)
36 – 41 Hourly SO2 concentration (µg SO2/m³) F 6 (171)
43 – 48 Hourly NO2 concentration (µg NO2/m³) F 6 (171)
50 – 55 Hourly NH3 concentration (µg NH3/m³) F 6 (171) 57 – 96 Other observations (text) C 40 (177)
XX2009.AQP data file to be used for data from passive samplers Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, sampler, date_start, date_end, compound, value, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number I 4 6 – 7 Country code (France = 01, etc.) I 2 X (1) 9 – 12 Plot number I 4 (2) 14 – 15 Sampler ID I 2 (169) 17 – 22 Start date measurement period (DDMMYY) Date (3) 24 – 29 End date measurement period (DDMMYY) Date (3) 31 – 33 Compound air quality C 3 X (167) 3 35 – 40 Value (O3 in ppb; NH3, NO2 and SO2 in µg /m ) F 6 (171) 42 – 81 Other observations (text) C 40 (177)
XX2011.COL Co-located passive samplers and continuous analyzers at intensive monitoring plots or at air quality station Each data file has to start with a comment line. This line starts with an exclamation mark:
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!Sequence, country, plot, latitude, longitude, altitude,compound, inlet_height, date_start, hour_start,date_end, hour_end, manufacturer, replicates, mean, stdev, mean_cont, percentage_valid, detection_limit, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number I 4 6 – 7 Country code (France = 01, etc.) (1) I 2 X (1) 9 - 12 Plot number (9999) or Station number (S999) I 4 (2) 14 - 20 Latitude in +DDMMSS C 7 (4) 22 - 28 Longitude in (+ or -) DDMMSS C 7 (4) 30 - 31 Altitude (in 50 m classes 1-51) I 2 X (32) Compound air quality measured (NH3, NO2, 33 - 35 C 3 X (167) O3, SO2) Inlet height (in m; accuracy 0.1m; only for 37 - 40 F 4 active samplers) 42 - 47 Start date measurement period (DDMMYY) Date (3) 49 - 50 Start time measurement period (HH) I 2 52 - 57 End date measurement period (DDMMYY) Date (3) 59 - 60 End time measurement period (HH) I 2 62 - 63 Passive sampler manufacturer C 2 X (170) Number of co-located passive samplers 65 - 66 I 2 (replicates) used for the measurement Mean value of replicates of co-located passive 68 - 73 F 6 (171) samplers Standard deviation of replicates of co-located 75 - 80 F 6 passive samplers Related continuous analyzer mean value for the 82 - 87 F 6 measurement period Related continuous analyzer percentage of valid 89 - 91 I 3 hourly data for the measurement period (%) Lowest detection limit of the continuous 93 - 98 F 6 analyzer 100 - 139 Observations (text) C 40 (177)
XX2009.AQB – Submission of Analyses of Blanks (blank passive samplers) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, sampler, date_start, date_end, compound, value, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number I 4 6 – 7 Country code (France = 01, etc.) I 2 X (1)
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9 – 12 Plot number I 4 (2) 14 – 15 Sampler ID I 2 (169) Start date of the exposure period of the exposed 17 – 22 samplers for which this is a travel blank Date (3) (DDMMYY) End date of the exposure period of the exposed 24 – 29 samplers for which this is a travel blank Date (3) (DDMMYY) 31 – 33 Compound air quality C 3 X (167) 35 – 40 Value F 6 (171) 42 – 81 Other observations (text) C 40 (177)
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SW Soil Water samples
4.14 Soil water
XX2009.SWC Soil water content – sample definition and dry soil bulk densityone record/line/observation on each sample unit Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, date, profile_pit, horizon, SW_pit, depth_layer, ring_depth_upper, ring_depth_lower, replicate, bulk_density, date_analysis, other_observations Columns parameter Format Ref_Tab Item# 1 – 4 Sequence number (1-9999) I 4 6 – 7 Country code I 2 X (1) 9 – 12 Plot Number I 4 (2) 14 – 19 Sampling date Date (3) 21 – 24 Profile pit ID (maximum 4 characters, same as C 4 (174) in BioSoil and PFH) 26 – 27 Horizon number I 2 (128) 29 – 33 Soil water pit ID C 5 (175) 35 – 37 Code depth layer C 3 (176) 39 – 41 Sample ring depth (upper side of ring) in cm below I 3 (176) the top of the mineral soil; negative values for sampling rings taken in organic layer. 43 – 45 Sample ring depth (lower side of ring) in cm below I 3 (176) the top of the mineral soil; so negative values for sampling rings taken in organic layer. 47 – 47 Replicate (in case multiple samples are taken I 1 (176) in one SW pit: 1, 2, 3…) 49 – 52 Dry soil bulk density of the fine earth (kg m-3) F 4 54 – 59 Date laboratory analysis (DDMMYY) Date (3) 61 – 100 Other observations (text) C 40 (177)
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XX2009.SWA FutMon D3 Soil water content – sample analysis results on water retention Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, date, SW_pit, depth_layer, replicate, water_content, matric_pressure, date_analysis, other_observations Columns parameter Format Ref_Tab Item# 1 – 5 Sequence number (1-99999) I 5 7 – 8 Country code I 2 X (1) 10 – 13 Plot Number I 4 (2) 15 – 20 Sampling date Date (3) 22 – 25 SW pit ID (maximum 4 characters) C 4 (175) 27 – 29 Code depth layer C 3 (176) 31 – 31 Replicate (in case multiple samples are taken I 1 (176) in one SW pit: 1, 2, 3…) 33 – 38 Volumetric water content in m3.m-3 at matric F 6 (199) pressure specified in field "matric pressure" 40 – 47 Matric pressure [kPa]; e.g. value -5 indicating F 8 (199) -5kPa; mandatory for new calculations under FutMon: 0kPa, -1kPa, -5kPa, -33kPa, -1500kPa 49 – 54 Date laboratory analysis (DDMMYY) Date (3) 56 – 95 Other observations (text) C 40 (177)
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GB
4.15 Ground Vegetation Biomass and Nutrients Analyses
XX2009.PGB Contents of reduced plot file to be used in combination with the survey of chemical content of ground vegetation Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, date,latitude, longitude, altitude, frame_area, frames, sampled_area,other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number of plots (1 to 9999) I 4 6 – 7 Country Code (France = 01, Belgium = 02, etc.) I 2 X (1) 9 – 12 Plotnumber (max. 9999) I 4 (2) 14 – 19 Date of sampling in DDMMYY (e.g. 220690) Date (3) 21 – 27 Latitude in +DDMMSS (e.g.+505852) C 7 (4) 29 – 35 Longitude in (+ or -)DDMMSS (e.g. +035531) C 7 (4) 37 – 38 Altitude (in 50 meter classes from 1 to 51) I 2 X (32) 40 – 43 Frame area [m²] F 4 (201) 45 – 46 No of frames I 2 (202) 48 – 52 Total sampled area [m²] F 5 (203) 54 – 93 Other observations (text) C 40 (177)
XX2009.GBM Contents of file with ground vegetation analysis information (mandatory) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, sample, date_analysis, mass, N, S, P, Ca, Mg, K, C, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence Number (1 to 99999) I 5 7 – 10 Observation Plot number (max. 9999) I 4 (2) 12 – 13 Sample number: Functional group C 2 X (200) 15 – 20 Date of analysis (DDMMYY) Date (3) 22 – 26 Mass of the sample [g] F 5 By reference at 105° dried material: 28 – 32 N [mg/g] F 5 34 – 38 S [mg/g] F 5
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Column Description Format Ref_Tab Item # 40 – 43 P [mg/g] F 4 45 – 49 Ca [mg/g] F 5 51 – 55 Mg [mg/g] F 5 57 – 61 K [mg/g] F 5 63 – 67 C [g/100g] F 5 69 – 108 other observations (text) C 40 (177) all parameters by reference at 105° dried material
XX2009.GBO Contents of file with ground vegetation analysis information (optional) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, sample, date_analysis, Zn, Mn, Fe, Cu, Pb, Cd, B, other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence Number (1 to 99999) I 5 7 – 10 Observation Plot number (max. 9999) I 4 (2) 12 – 13 Sample number: Functional group C 2 X (200) 15 – 20 Date of analysis (DDMMYY) Date (3) By reference at 105° dried material: 22 – 26 Zn [μg/g] F 5 28 – 32 Mn [μg/g] F 5 34 – 39 Fe [μg/g] F 6 41 – 45 Cu [μg/g] F 5 47 – 51 Pb [μg/g] F 5 53 – 57 Cd [ng/g] F 5 59 – 63 B [μg/g] F 5 65 – 104 other observations (text) C 40 (177) all parameters by reference at 105° dried material
XX2009.GBH form to be used for submission of height of sampled species (at least 5 most abundant) within frames Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, plot, sample, date_analysis, species, height,other_observations Column Description Format Ref_Tab Item # 1 – 5 Sequence Number (1 to 99999) I 5 7 – 10 Observation Plot number (max. 9999) I 4 (2)
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Column Description Format Ref_Tab Item # 12 – 13 Sample number: Functional group C 2 X (200) 15 – 20 Date of analysis (ddmmyy) Date (3) 22 – 32 Species code (Ground Vegetation Suvey) C 11 X (97) 34 – 37 Height of species [cm] F 4 39 – 78 Other observations (text) C 40 (177)
XX2009GB.LQA Ground Vegetation Biomass – Laboratory QA/QC information Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, date_start, date_end, parameter, pretreatment, determination, quantification_limit, control_chart_mean, control_chart_std, ring_test_participation, ring_test_number, Laboratory_ID, percentage_within, requalification, percentage_within_requal, other_observations Column Description Format Ref_Tab Item # 01 – 04 Sequence number (1 to 9999) I 4 06 – 07 Country code (France = 01, Belgium = 02, etc.) I 2 X (1) 09 – 12 Observation Plot number (maximum 9999) I 4 (2) 14 – 19 start date Date (188) 21 – 26 end date Date (188) 28 – 29 Parameter Code (N, S, Ca etc.) C 2 X (181) 31 – 34 Pretreatment method (see reference list) F 4 X (178) 36 – 39 Determination method (see reference list) F 4 X (179) 41 – 46 Quantification limit (unit of parameter) F 6 (180) 48 – 53 Mean of control chart F 6 (180)
55 – 57 Relative Standard Deviation [%] F 3 (180) 59 Participated at ring Test (yes = 1, no = 0) I 1 (180) ICP Forests Ring Test Number (Needle/Leaf 61 – 63 C 3 (180) Interlaboratory Test) 65 – 67 ID of laboratory (e.g. H45, B78, etc.) C 3 (180) Percentage [%] of the results of the ring tests 69 – 71 I 3 (180) within tolerable limits for each ring test 73 Requalification information (yes = 1, no = 0) I 1 (180) Percentage [%] of the results of the ring tests 75 – 77 within tolerable limits for each ring test in I 3 (180) requalification 79 – 118 Other observations (freetext) C 40 (177)
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4.16 Leaf Area Index (LAI) and Radiation Measurements
XX2012.PLA reduced plot file on LAI measurements Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot ,latitude, longitude, altitude, slope, exposition, date_LAI, LAI_survey_ID, determination, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number of plots (1 to 9999) I 4 Country Code (France = 01, Belgium = 02, I 2 X (1) 6 – 7 etc.) 9 – 12 Plotnumber (max. 9999) I 4 (2) 14 – 20 Latitude in +DDMMSS (e.g.+505852) C 7 (4) Longitude in (+ or -)DDMMSS C 7 (4) 22 – 28 (e.g. +035531) 30 – 31 Altitude (in 50 meter classes from 1 to 51) I 2 X (32) 33 – 34 Slope in degree I 2 36 – 38 Exposition in degree 1 to 360 I 3 40 – 45 Date of measurement Date (3) 47 – 49 LAI survey ID I 3 (189) 51 – 52 Method of determination I 2 X (190) 54– 93 Other observations (text) C 40 (177)
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Form XX2009.LAC (coordinates of LAI measurement points and other surveys) was shifted to System installment (starting with 2011 data).
XX2012.LAI Leaf Area Index (LAI) summarized measurement outcome LAI form is mandatory to submit LAImax Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot,LAI_survey_ID,date_maxfol,LAImax,PAIeff,PAIeff_maxfol,other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number (1 to 9999) I 4 6 – 7 Country code (France = 01, Belgium = 02, etc.) I 2 X (1) 9 – 12 Observation Plot number (maximum 9999) I 4 (2) 14 – 16 LAI_Survey ID I 3 (189) 18 – 23 Date of maximum foliation (DDMMYY) Date (191) 2 2 25 – 28 LAImax (m /m ) F4 (192) 2 2 30 – 33 PAIeff(m /m ) F4 (191) 35 – 74 Other observation (text) C 40 (177)
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XX2012.LAM Leaf Area Index (LAI) results ofhemispherical measurements Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, LAI_survey_ID, time, point_ID,parameter, value,date_SAI,sky,sun, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number (1 to 9999) I 4 6 – 7 Country code (France = 01, Belgium = 02, etc.) I 2 X (1) 9 – 12 Observation Plot number (maximum 9999) I 4 (2) 14 – 16 LAI survey ID I 3 (189) Time of field observation (HHMMSS) (e.g. 18 – 23 C 6 095401) Point ID 25 – 26 I 2 (193) (99 = plot mean calculated) 28 - 30 Parameter Code I 3 (194) 32 – 35 Specified value F4 Date of related SAI measurement (winter, if 37 – 42 Date (195) applicable) (DDMMYY) 44 – 45 Sky conditions I 2 X (196) 47 – 48 Sun position I 2 X (197) 50 – 89 Other observation (text) C 40 (177)
XX2009.LAP Leaf Area Index (LAI) photo documentationfor hemispherical photos Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, LAI_survey_ID, time, point_ID, photo_file,camera,lens,exposure, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number (1 to 9999) I 4 Country code (France = 01, Belgium = 02, 6 – 7 I 2 X (1) etc.) 9 – 12 Observation Plot number (maximum 9999) I 4 (2) 14 – 16 LAI survey ID I 3 (189) Time of field observation (HHMMSS) (e.g. 18–23 C 6 095401) Point ID 25 – 26 I 2 (193) (99 = plot mean calculated)
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photo file name 28 – 55 C 28 (86) [XXPPPPNNNNDDDDDDTTTTTTSS.jpg] 57 – 76 Camera brand and model C 20 78 – 97 Lens brand and model C 20 99 – 103 Exposure setting F 5 (198) 105 – 144 Other observation (text) C 40 (177)
XX2012.LLF Results of direct LAI measurements (Litterfall) Each data file has to start with a comment line. This line starts with an exclamation mark: !Sequence, country, plot, LAI_survey_ID,date_start,date_end, date_analysis, species, traps, collecting_area, date_max_foliation,parameter,value, other_observations Column Description Format Ref_Tab Item # 1 – 4 Sequence number of plots (1 to 9999) I 4 Country Code (France = 01, Belgium = 02, I 2 X (1) 6 – 7 etc.) 9 – 12 Plotnumber (max. 9999) I 4 (2) 14 – 16 LAI survey ID I 3 (189) Sampling period (from) in DDMMYY (e.g. Date (3) 18 – 23 010611) Sampling period (till) in DDMMYY (e.g. Date (3) 25 – 30 290312) Date of analysis in (DDMMYY) (e.g. Date (3) 32 – 37 140412) 39 – 41 Tree species, (888 for “all species”) I 3 X (42) 43 – 44 Number of traps installed on plot I 2 46 – 49 Total Collecting area (in m2) F 4
51 – 55 SLAi (species mean in cm²/g) F 5 (204)
57 – 60 Yearly cumulated LAI per species (LAIcum, i) F 4 (204) LAI cumulated after date of maximum F 4 (204) 62 – 65 foliation, per species (LAImax, i) 67 – 70 Average area of leaves (cm²/leaf) F 4 (204) 72 – 75 Standard deviation of average area of leaves F 4 (204) 77 – 116 Other observations (text) C 40 (177)
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5 Explanatory Items
1. Country code (France = 1, Belgium = 2, etc.) (all) Code Country Code Country 1 France 59 Estonia 2 Belgium 60 Slovenia 3 Netherlands 61 Republic of Moldova 4 Germany 62 Russia 5 Italy 63 Bulgaria 6 United Kingdom 64 Latvia 7 Ireland 65 Belarus 8 Denmark 66 Cyprus 9 Greece 67 Serbia 10 Portugal 68 Andorra 11 Spain 69 Malta 12 Luxembourg 70 Monaco 13 Sweden 71 Albania 14 Austria 72 Turkey 15 Finland 73 Liechtenstein 50 Switzerland 74 Ukraine 51 Hungary 75 Iceland 52 Romania 76 Holy See (Vatican City State) 53 Poland 77 San Marino 54 Slovak Republic 78 Former Yugoslavian Republic of Macedonia 55 Norway 79 Bosnia and Herzegovina 56 Lithuania 80 Montenegro 57 Croatia 95 Canaries (Spain) 58 Czech Republic 96 Azores (Portugal)
2. Observation plot number (maximum Level II 9999, Level I 999999) (all) The observation plot number corresponds to a unique number given to the permanent plot during the selection or installation.
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3. Date of observation, date of assessment, date of analysis (all) Dates shall be completed in the following order (day, month and year):
DDMMYY
Day Month Year 31 03 09
310309
4. Latitude-longitude coordinates (all) The coordinates of plot and subplot centres or reference points are specified in degree, minutes and seconds (WGS84): Fill in the full six figure latitude and longitude coordinates of the centre of the observation plot, e.g: +/- Degress Minutes Seconds — latitude + 5 0 2 0 2 7 — longitude - 0 1 1 5 3 2 the first box/digit is used to indicate a + or – coordinate +502027 and -011532 to be submitted The coordinates need to be expressed in a sexagesimal system (base 60). So minuets and seconds should never exceed ‘59’.
5. Plot design (SI, Y1) The plot design of Level I and Level II plots is described using the following codes:
Code Description 110 Level I cross-cluster plot (e.g. Figure 1 a) 120 Level I circular fixed area (one radius defined) 121 Level I circular fixed area (more than one radius for one centre point defined; e.g. Figure 1 b and c) 122 Level I more than one circles (distinct centres) 123 Relascope used to determine trees 130 Level I combination of 110 and 120 131 Level I combination of 110 and 121 140 Level I quadratic plot 141 Level I rectangular plot 150 Level I polygonal plot
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Code Description 199 other Level I plot design 210 Level II quadratic plot 211 Level II rectangular plot 220 Level II polygonal plot 230 Level II circular fixed area (one radius defined) 231 Level II circular fixed area (more than one radius for one centre point defined) 232 Level II more than one circles (distinct centres) 299 other Level II plot design
N
E 1 1 2
2 3
25 m S
A. Cross-cluster sample, B. Circular plot, C. BioSoil plot, undefined shape and area defined shape and area defined shape and area Figure 1: Examples of designs adopted for Level I plots in Europe. A. Cross-cluster; B. Circular: 1, subplot for all tree above given DBH thresholds; 2, subplot for large trees only; C. BioSoil plot: 1, 30 m2 subplot; 400 m2 subplot; 2000 m2 subplot. (Drawing: M. Ferretti).
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Access road off-site measurements: Meteorology Bulk deposition Gaseous pollutants Ozone injury at forest edge
Open areas Forest
Access road Monitoring site in-site measurements: Path to access the site Tree condition Tree growth Buffer zone Tree phenology Ozone injury on MTS Plot Soil Soil solution Foliar chemistry Litterfall Throughfall/stemflow
Sub-plots (when necessary)
Figure 2: Example of location of a monitoring site and its possible organization, with buffer zone, plot and sub-plots. In-site measurements are those that must be carried out within the site; off-plot measurements are those to be carried out in an open area close to the plot. Note that different shape (e.g rectangles, polygons) and size (min 0.25 ha) are possible, as well as different type of internal organization of the plot. Size and shape must however be known and reported (Drawing: M. Ferretti).
6. Local/metric X and Y coordinates (SI) The plot centre is defined by geographic latitude and longitude coordinates (see (4)) and these coordinates are submitted to the programme data centre with form XXGENER.PLT. X and Y coordinates of local plot centregive the position of a local plot centre in relation to the plot centre. They are specified with “0” if the plot centre is the origin of the local metric coordinate system. In any case the orientation of the local metric coordinate system must be from west to east (X coordinate) and from south to north (Y coordinate). E.g X (Y) coordinate “17.83” means that the local plot centre is 17 meters and 83 centimeters east (north) of the plot centre, “-5.61” means that the respective point is 5 meters and 61 centimeters west (south) of the plot centre. X coordinate and Y coordinate in the forms LAC and TCO give the position of measurement devices or trees in relation to the local plot centreas specified in forms PLT or PL1. Note: All geographic coordinates which are specified in the reduced plots files are the coordinates of the plot centre mentioned above. All coordinates are defined in horizontal level (compareFigure 3). Thus, if a horizontal distance (coordinate difference or radius) from one point (A) to another (B) must be measured at a slope, the horizontal distance (h) has to be used for coordinate calculations instead of the slope parallel one (s). The horizontal distance can be calculated from slope parallel distance and slope as follows: h = s * cos(α)
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Figure 3: Adjustment of a distance between two points for slope
In analogy, the elevation difference (e) between both points can be calculated as: e = s * sin(α) Note: It is important that distance (s) and slope (α) are measured in the same direction!
7. Stand history (SI, Y1) Code Description 1 Forested more than 300 years 2 Forested more than 100 years 3 Forested 25 – 100 years ago 4 Forested in the past 25 years 9 unknown
8. Previous land use (SI, Y1) Previous land use information is reported using the code below. That land use shall be classified which had been at the respective area before the actual stand has been established.
Code Description 1 farmland, cropland 2 grassland 3 pasture, including silvo-
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pastural systems 4 drained wetland 5 primary forest 6 other 9 unknown
9. Origin of actual stand (SI, Y1) Code Description 1 Planted 2 Seeded 3 Natural regeneration 4 Mixed 9 Unknown
10. Type of tree species mixture (SI, Y1) Code Description 1 Monoculture 2 Single tree wise mixture 3 Group wise mixture 4 Mixture by layers 9 Irregular, none of the above
11. Top Height (SI) Average top height can be derived from measured values (usually the case at Level II plots) or from estimates. The method of determination is to be indicated in the data submission forms. Top height is defined here as the mean height of the 100 thickest stems per ha. For more details on the calculations see explanatory item (73) on absolute top height. It is determined and submitted with an accuracy of 10cm.
12. Top height determination (SI) Code Description 1 all heights measured and top height calculated from them 2 heights of at least 10 trees of the 100 thickest were measured 3 Top height was calculated based on earlier measurement of all relevant trees 4 Top height was calculated based on earlier measurement of at least 10 trees of the 100 thickest trees
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5 Top height was calculated based on locally adapted dbh/height tables 9 other method (please specifiy in data accompanying report)
13. Forest Type (SI, Y1) The forest type of the plot is reported following the nomenclature of State of Europe’s Forests Report 2011 (FOREST EUROPE, UNECE and FAO 2011: State of Europe’s Forets 2011. Status and Trends in Sustainalbe Forest Management in Europe. 337 pp). 1 Boreal forest Extensive boreal, species-poor forests, dominated by Picea abies and Pinus sylvestris. Deciduous trees including birches (Betula spp.), aspen (Populus tremula), rowan (Sorbus aucuparia) and willows (Salix spp.) tend to occur as early colonisers. 2 Hemiboreal Latitudinal mixed forests located in between the boreal and nemoral (or and nemoral temperate) forest zones with similarcharacteristics to EFT 1, but a coniferous and slightly higher tree species diversity, including also temperate mixed deciduous trees likeTilia cordata, Fraxinus excelsior, Ulmus glabra and broadleaved- Quercus robur. Includes also: pure and mixed forests in thenemoral coniferous forest zone dominated by coniferous species native within the borders forest of individual FOREST EURO PEmember states like Pinus sylvestris, pines of the Pinus nigra group, Pinus pinaster, Picea abies, Abies alba. 3 Alpine forest High-altitude forest belts of central and southern European mountain ranges, covered by Picea abies, Abies alba,Pinus sylvestris, Pinus nigra, Larix decidua, Pinus cembra and Pinus mugo. Includes also the mountain forestdominated by birch of the boreal region. 4 Acidophilous Scattered occurrence associated with less fertile soils of the nemoral oak and forest zone; the tree species composition ispoor and dominated by oakbirch forest acidophilous oaks (Q. robur, Q. petraea) and birch (Betula pendula). 5 Mesophytic Related to medium rich soils of the nemoral forest zone; forest deciduous composition is mixed and made up of a relativelylarge number of forest broadleaved deciduous trees: Carpinus betulus, Quercus petraea, Quercus robur, Fraxinus, Acerand Tilia cordata. 6 Beech forest Widely distributed lowland to submountainous beech forest. Beech, Fagus sylvatica and F. orientalis (Balkan) dominate, locally important is Betula pendula. 7 Mountainous Mixed broadleaved deciduous and coniferous vegetation belt in the beech forest main European mountain ranges. Speciescomposition differs from EFT 6, including Picea abies, Abies alba, Betula pendula and mesophytic deciduoustree species. Includes also mountain fir dominated stands. 8 Thermophilous Deciduous and semi-deciduous forests mainly of the Mediterranean deciduous region dominated by thermophilous species, mainly of Quercus; Acer, forest Ostrya, Fraxinus, Carpinus species are frequent as associated secondary trees.Includes also Castanea sativa dominated forest. 9 Broadleaved Broadleaved evergreen forests of the Mediterranean and Macaronesian evergreen regions dominated by sclerophyllous orlauriphyllous trees, mainly forest Quercus species. 10 Coniferous Varied group of coniferous forests in Mediterranean, Anatolian and forests of the Macaronesian regions, from the coast tohigh mountains. Dry and often Mediterranean, poorly-developed soils limit tree growth. Several tree species, including
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Anatolian and a number of endemics, of Pinus, Abies and Juniperus species. Macaronesian regions 11 Mire and Wetland forests on peaty soils widely distributed in the boreal region. swamp forest Water and nutrient regimes determine thedominant tree species: Pinus sylvestris, Picea abies or Alnus glutinosa. 12 Floodplain Riparian and riverine species-rich forests characterised by different forest assemblages of species of Alnus, Betula,Populus, Salix, Fraxinus, Ulmus. 13 Non-riverine Pioneer forests dominated by Alnus, Betula or Populus. alder, birch or aspen forest 14 Introduced tree Introduced tree species can be identified at regional (recommended) or species national level and comprise: forestForests • tree species that are not native to Europe (e.g. Eucalyptus spp., dominated by Robinia pseudoacacia, Acaciadealbata, Ailanthus altissima, Prunus introduced serotina, Quercus rubra, Fraxinus alba, Picea sitchensis, Pinuscontorta, trees above Pinus banksiana, Pseudotsuga menziesii, Tsuga heterophylla); categories. • tree species native to Europe, but not naturally occurring within the borders of individual countries; • tree species native only in some regions of an individual country.
14. Number of tree layers (SI, Y1) Code Description 1 One Layer 2 Two layers (each min of 10 % coverage); 3 Multilayered (each min of 10% coverage) 9 Irregular
15. Coverage of tree layers (SI) The coverage of each layer is reported in 5% steps, only layers are included that have at least a 10% coverage. The sum of the coverages of all tree layers may be > 100%. The coverage estimate refers to the plot area, whereas tree coverage estimates conducted within the ground vegetation survey are related to the ground vegetation subplot. Coverage of tree layers is estimated as a projection of branches and foliage to the plot surface.
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16. Canopy Closure (SI) Canopy closure is reported as the estimated percentage coverage of tree layer > 5 m in 5% steps. The maximum value is 100% as multiple coverage is not considered separately. In single layered stands the sum of the coverage of all tree layers = canopy closure. As layers may overlap, the sum of the coverage of the layers may be higher than the canopy closure. The canopy closure estimate refers to the plot area, whereas tree coverage estimates conducted within the ground vegetation survey are related to the ground vegetation subplot. Canopy closure is estimated as a projection of branches and foliage to the plot surface. If canopy closure has not been determined in 2011 insert 999 and determine canopy closure in 2012. For reporting of Level I data in 2012 the 999 code will not be valid anymore
17. Forest protection (SI, Y1) The Protection status of the monitoring plot is described following the MCPFE classification (FOREST EUROPE/UNECE/FAO 2010): MCPFE Class 1.1: No Active Intervention The main management objective is biodiversity. No active, direct human intervention is taking place. Activities other than limited public access and non-destructive research not detrimental to the management objective are prevented in the protected area. MCPFE Class 1.2: Minimum Intervention Guidelines The main management objective is biodiversity. Human intervention is limited to a minimum. Activities other than listed below are prevented in the protected area : - ungulate/game control -control of diseases/insect outbreaks* -public access - fire intervention - non-destructive research not detrimental to the management objective -subsistence resource use ** * in case of expected large disease/insect outbreaks control measures using biological methods are allowed, provided no other adequate control possibilities in the buffer zone are feasible. ** subsistence use to cover the needs of indigenous people and local communities, in so far as it will not adversely affect the objectives of management MCPFE Class 1.3: Conservation Through Active Management The main management objective is biodiversity A management with active interventions directed to achieve specific conservation goal of the protected area is taking place
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Any resource extraction, harvesting, silvicultural measures detrimental to the management objective, as well as other activities negatively affecting the conservation goal, are prevented in the protected area. MCPFE Class 2 : Main Management Objective ‘Protection of Landscape and Specific Natural Elements’ Interventions are clearly directed to achieve the management goals landscape diversity, cultural, aesthetic, spiritual and historical values, recreation, specific natural elements. The use of forest resources is restricted. A clear long-term commitment and an explicit designation as specific protection regime, defining a limited area is existing. Activities negatively affecting characteristics of landscapes or/and specific natural elements mentioned are prevented in the protected area. MCPFE Class 3 : Main Management Objective ‘Protective Functions’ The management is clearly directed to protect soil and its properties or water quality and quantity other forest ecosystem functions, or to protect infrastructure and managed natural resources against natural hazards. Forests and other wooded lands are explicitly designated to fulfil protective functions in management plans or other legally authorised equivalents. Any operation negatively affecting soil or water or the ability to protect other ecosystem functions, ability to protect infrastructure and managed natural resources against natural hazards is prevented.
Code Description 1 MCPFE Class 1.1: Main Management Objective “Biodiversity”- “No Active Intervention” 2 MCPFE Class 1.2: Main Management Objective “Biodiversity”- “Minimum Intervention” 3 MCPFE Class 1.3: Main Management Objective “Biodiversity”- “Conservation Through Active Management” 4 MCPFE Class 2: Main Management Objective "Protection of Landscapes and Specific Natural Elements" 5 MCPFE Class 3: Main Management Objective “Protective Functions” 9 No protection status
18. Fencing (SI, Y1) Fencing is reported in classes. Code Description 1 Fenced 2 Not Fenced 3 Fenced in parts
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19. Non timber utilisation (SI, Y1) Non-timber utilisation is reported in classes. Only regular non-timber utilization is to be reported which may have a measurable impact on nutrient and water cycles. Do not report very occasional utilizations. Code Description 1 Grazing 2 Fire wood collection 3 Litter raking 4 Other 9 No non-timber utilization
20. Management type (SI, Y1) Management type is reported in classes. Code Description 1 High forest 2 Coppice without standards 3 Coppice with standards
21. Intensity of management (SI, Y1) Intensity of management is reported in classes. Code Description 1 Unmanaged (no evidence) 2 Management (evidence but for more than 10 years ago) 3 Managed (within the last 10 years) 9 Unknown
22. Management method (SI, Y1) Management method is reported in classes. Code Description 1 clear cut 2 clear cut with reservoirs 3 selective cut 4 shelterwood 9 Unknown
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23. Forest ownership (SI, Y1) Forest ownership is reported in classes following the FAO Forest Resource Assessment 2010 (FRA 2010,www.fao.org/forestry/fra) Public ownership: forest owned by the State; or administrative units of the public administration; or by institutions or corporations owned by the public administration. Private ownership: forest owned by individuals, families, communities, private co- operatives, corporations and other business entities, private religious and educational institutions, pension or investment funds, NGOs, nature conservation associations and other private institutions. o Individuals (sub-category of Private ownership): Forest owned by individuals and families. o Private business entities and institutions (sub-category of Private ownership): Forest owned by private corporations, co-operatives, companies and other business entities, as well as private non-profit organizations such as NGOs, nature conservation associations, and private religious and educational institutions, etc. o Local communities (sub-category of Private ownership): Forest owned by a group of individuals belonging to the same community residing within or in the vicinity of a forest area. The community members are co-owners that share exclusive rights and duties, and benefits contribute to the community development. o Indigenous / tribal communities (sub-category of Private ownership): Forest owned by communities of indigenous or tribal people. Other types of ownership:Other kind of ownership arrangements not covered by the categories above. Also includes areas where ownership is unclear or disputed.
Code description 1 Public ownership 2 Private ownership 21 Private ownership: Individuals 22 Private ownership: Private business entities and institutions 23 Private ownership: Local communities 24 Private ownership: Indigenous / tribal communities 6 Other types of ownership 9 unknown
24. Plot status (SI, Y1) For each plot it has to be submitted in case that plot status has changed. This information is used for data validation and evaluation. Use the following codes:
Code description 1 Plot is active (at least one survey has been conducted in reported year)
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2 Plot was newly installed in reported year 3 Plot was re-activated 9 Plot is not active
25. NFI status (SI, Y1) It has to be submitted if the plot is identical or co-located with a plot of the National Forest Inventory. This information is used for cross-linkage and data evaluation..
Code description 1 Plot is in addition NFI plot, same sample for both monitoring schemes 2 Plot is co-located with a NFI plot 9 No combination with NFI at this plot
26. Two letter code of Surveys (SI) code Survey SI System Installation on Level II Y1 System Installation on Level I CC Crown Condition SO Soil SS Soil Solution FO Foliage GR Growth and Yield GV Ground Vegetation GB Ground Vegetation Biomass DP Deposition MM Meteorology PH Phenology OZ Ozone AQ Air Quality LF Litterfall LA Leaf Area Index TV Tree Vitality SW Soil Water C1 Cronw Condition Level I F1 Foliage Level I S1 Soil Level I G1 Growth Level I
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27. Device_ID (SI) Each device (deposition sampler, litterfall trap etc.) or measurement point on LAI plot shall be numbered in a permanent and unique way (1-999).
28. Tree within Level II plot (SI) A tree which is in the area of a Level II plot, usually 0.25 ha is within a Level II plot. A tree which is located in the bufferzone or in a subplot outside the core area is not within the Level II plot.
29. Status of tree (SI)
Code Description 1 Standing living tree 2 Standing dead tree 3 Lying dead tree
30. Availability of water to principal species (estimate) (CC) Code description 1 Insufficient 2 Sufficient 3 Excessive
31. Humus type (CC, SO) Code description 1 Mull 2 Moder 3 Mor 4 Amphi (or Amphihumus) 5 Anmoor 6 Histomull 7 Histomoder 8 Histomor 9 Histoamphi
32. Altitude (all)
Code lower upper code lower upper code lower upper code lower upper 1 50 m 14 651— 700 m 27 1301— 1350 m 40 1951— 2000 m
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2 51— 100 m 15 701— 750 m 28 1351— 1400 m 41 2001— 2050 m 3 101— 150 m 16 751— 800 m 29 1401— 1450 m 42 2051— 2100 m 4 151— 200 m 17 801— 850 m 30 1451— 1500 m 43 2101— 2150 m 5 201— 250 m 18 851— 900 m 31 1501— 1550 m 44 2151— 2200 m 6 251— 300 m 19 901— 950 m 32 1551— 1600 m 45 2201— 2250 m 7 301— 350 m 20 951— 1000 m 33 1601— 1650 m 46 2251— 2300 m 8 351— 400 m 21 1001— 1050 m 34 1651— 1700 m 47 2301— 2350 m 9 401— 450 m 22 1051— 1100 m 35 1701— 1750 m 48 2351— 2400 m 10 451— 500 m 23 1101— 1150 m 36 1751— 1800 m 49 2401— 2450 m 11 501— 550 m 24 1151— 1200 m 37 1801— 1850 m 50 2451— 2500 m 12 551— 600 m 25 1201— 1250 m 38 1851— 1900 m 51 > 2500 m 13 601— 650 m 26 1251— 1300 m 39 1901— 1950 m
33. Orientation (SI, Y1, CC, C1) Code description 1 N 2 NE 3 E 4 SE 5 S 6 SW 7 W 8 NW 9 flat
34. Mean age of dominant storey (years) (SI, Y1, C1) Code description 1 ≤ 20 2 21— 40 3 41— 60 4 61— 80 5 81—100 6 101—120 7 > 120 8 Irregular stands
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35. Tree age (CC) Code description 1 ≤ 20 2 21— 40 3 41— 60 4 61— 80 5 81—100 6 101—120 7 121—140 8 141—160 9 >160
36. Apical shoot architecture (Beech) (CC) Code Description
1 Exploratory phase: Apical shoots and upper side buds form long shoots. Flat, longitudinal, expansive shoot development. 2 Intermediary form 1/3 Degeneration phase: Only apical bud forms long shoot. Shoots of side buds are 3 stunted. Spear-shaped development of main shoots with reduced side shoot formation "spear-shaped". 4 Intermediary form 3/5 5 Stagnation phase: Stunted long shoots, claw-like appearance because of pluriannual short shoot chains. 6 Intermediary form 5/7 7 Resignation phase: Die-back of twigs of the topmost part of the crown or even the whole crown itself.
37. Method of age determination (CC) Code description 1 assured dates of stand establishment 2 tree stumps age determination of the lowermost twigs (add 3 estimated time it has taken to grow to that height) increment borer, stem discs (from similar sized 4 trees/median sized trees) outside the plot 5 assessment (impossible in most cases) 6 estimation without any exact information
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38. Crown diameter related distance to neighbours (CC) Calculation:
[Score1 + Score2 + Score3 + Score4] / 4 = CDRD_N
Score for Description calculation 1 cramped. Canopies overlap. 2 closed. Crowns touch one another. 3 loose spread. Gap between crowns up to one third of average crown diameter Gap between crowns up to two thirds of average crown 4 spread. diameter Gap between crowns from two thirds up to one whole of 5 Distant. average crown diameter 6 very distant. Gap between crowns > than 1/1 of average crown diameter
39. Total plot size in hectares or sub-plot size or growth (=sample) plot size (SI, Y1, GR, G1) The size of the total plot or sub-plot shall be stated in hectares with 1m² accuracy (e.g. 0.0001 ha). In case of Level I cross cluster plots (compare (5)) no plot size (-1) has to be submitted.Within the GR survey the growth plot size refers to the area on which tree growth was measured, i.e. the area to which the growth information is related. In most cases this equals the total plot size of the Level II plot or the subplot (as submitted within systm installment - SI), but deviations may occur based on national samplingapproaches (e.g. growth plotsize as sum of several subplots with growth data submission).
40. Number of trees in total plot (SI, GR) The total number of trees (shoots in coppice forests) in the total plot. All trees (shoots) from 5 (3) cm (DBH) and more are counted.
41. Sample tree number (SI, CC, C1, FO, GR, GR1, PH, OZ, LA) The tree number is the number which has been assigned to the tree during the installation of the plot. On Level II plots the tree number should be permanently marked. The tree number must be unique and must not change over time.
Note: a copy of the numbers of sample trees that were assessed the year before and which must be included in the assessment in the current year should be provided to the surveyors each year. Further information should not be supplied as repeated assessments of, for example, species, will act as a control on the quality of the observations.
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42. Main tree species (Reference Flora Europaea) (SI, CC,C1, FO, GR, G1, PH, OZ, LF, LA) Broadleaves (* = species to be used for the foliage inventory) 51: Quercus robur (Q. pedunculata)* 52: Quercus rotundifolia* 000: Unknown 53: Quercus rubra* 54: Quercus suber* 1: Acer campestre* 55: Quercus trojana 2: Acer monspessulanum* 56: Robinia pseudoacacia* 3: Acer opalus 57: Salix alba 4: Acer platanoides 58: Salix caprea 5: Acer pseudoplatanus* 59: Salix cinerea 6: Alnus cordata* 60: Salix eleagnos 7: Alnus glutinosa* 61: Salix fragilis 8: Alnus incana* 62: Salix sp. 9: Alnus viridis 63: Sorbus aria 10: Betula pendula* 64: Sorbus aucuparia 11: Betula pubescens* 65: Sorbus domestica 12: Buxus sempervirens 66: Sorbus torminalis 13: Carpinus betulus* 67: Tamarix africana 14: Carpinus orientalis 68: Tilia cordata 15: Castanea sativa (C. vesca)* 69: Tilia platyphyllos 16: Corylus avellana* 70: Ulmus glabra (U. scabra, U. scaba, U. 17: Eucalyptus sp.* montana) 18: Fagus moesiaca* 71: Ulmus laevis (U. effusa) 19: Fagus orientalis* 72: Ulmus minor (U. campestris, U. carpinifolia) 20: Fagus sylvatica* 73: Arbutus unedo 21: Fraxinus angustifolia spp. oxycarpa (F. 74: Arbutus andrachne oxyphylla)* 75: Ceratonia siliqua 22: Fraxinus excelsior* 76: Cercis siliquastrum 23: Fraxinus ornus* 77: Erica arborea* 24: Ilex aquifolium 78: Erica scoparia 25: Juglans nigra 79: Erica manipuliflora 26: Juglans regia 80: Laurus nobilis 27: Malus domestica, Malus sylvestris 81: Myrtus communis 28: Olea europaea* 82: Phillyrea latifolia 29: Ostrya carpinifolia* 83: Phyllyrea angustifolia 30: Platanus orientalis 84: Pistacia lentiscus 31: Populus alba 85: Pistacia terebinthus 32: Populus canescens* 86: Rhamnus oleoides 33: Populus hybrides* 87: Rhamnus alaternus 34: Populus nigra* 88: Betula tortuosa 35: Populus tremula* 36: Prunus avium* 90: Crataegus monogyna 37: Prunus dulcis (Amygdalus communis) 91: Ilex canariensis 38: Prunus padus 92: Laurus azorica 39: Prunus serotina 93: Myrica faya 40: Pyrus communis, Pyrus pyraster 98: Quercus petrea_or_robur 41: Quercus cerris* 99: Other broadleaves 42: Quercus coccifera (Q. calliprinos)* 201: Quercus hartwissiana 43: Quercus faginea* 202: Quercus vulcanica 44: Quercus frainetto (Q. conferta)* 203: Quercus infectoria 45: Quercus fruticosa (Q. lusitanica) * 204: Quercus macranthera 46: Quercus ilex* 205: Quercus libani 47: Quercus macrolepis (Q. aegilops) 206: Quercus brantii 48: Quercus petraea* 207: Quercus ithaburensis 49: Quercus pubescens* 208: Quercus aucheri 50: Quercus pyrenaica (Q. toza)* 209: Tilia spp. 210: Populus spp. 211: Platanus hybrides 212: Betula spp.
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213: Ulmus spp. 214: Betula x hybrida
Conifers (* = species to be used for the foliage inventory) 128: Pinus mugo (P. montana) * 100: Abies alba* 129: Pinus nigra* 114: Juniperus sabina 101: Abies borisii-regis* 130: Pinus pinaster* 115: Juniperus thurifera* 102: Abies cephalonica* 131: Pinus pinea* 116: Larix decidua* 103: Abies grandis 132: Pinus radiata (P.insignis)* 117: Larix kaempferi (L.leptolepis) 104: Abies nordmanniana* 133: Pinus strobus 118: Picea abies (P. excelsa)* 105: Abies pinsapo 134: Pinus sylvestris* 119: Picea omorika 106: Abies procera 135: Pinus uncinata* 120: Picea sichensis* 107: Cedrus atlantica 136: Pseudotsuga menziesii* 121: Pinus brutia* 108: Cedrus deodara 137: Taxus baccata 122: Pinus canariensis* 109: Cupressus lusitanica 138: Thuja spp. 123: Pinus cembra* 110: Cupressus sempervirens 139: Tsuga spp. 124: Pinus contorta* 111: Juniperus communis 140: Chamaecyparis lawsoniana 125: Pinus halepensis* 112: Juniperus oxycedrus* 141: Cedrus brevifolia 126: Pinus heldreichii 113: Juniperus phoenicea 147: Abies amabilis 127: Pinus leucodermis
199: Other conifers For Leaf area and Litterfall: 888 all species
43. Removals and mortality (CC, C1) The following classification must be used:
Tree is in sample and values for parameters (e.g. defoliation) were assessed and submitted: Code for tree alive and measurable (note: this is different than a missing value) 01 tree alive, in current and previous inventory (formerly blanc) 02 new alive tree (ingrowth) 03 alive tree (present but not assessed in previous inventory)
Tree is not in sample or at least no data are available for this tree in the submitted year: 04 alive tree but tree not longer in crown sample due to heavydisturbances (e.g. heavy storm damage); may be assessed and datasubmitted 07 no info on this tree with this submission (e.g. tree forgotten during field work) 08 alive tree but due to alternating tree selection not in submitted sample
Tree has been cut and removed, only its stump has been left 11 planned utilization, e.g. thinning 12 utilization for biotic reasons, e.g. insect damage 13 utilization for abiotic reasons, e.g. windthrow 14 cut, reason unknown 18 reason for disappearance unknown 19 reason for disappearance not determined/observed
Tree is still standing and alive, but crown condition parameters are no longer assessed 21 lop-sided or hanging tree 22 heavy crown break (over 50% of the crown) or broken stem
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23 tree is no longer in Kraft classes 1, 2 or 3 (not applicable to the first inventory in a plot) 29 other reasons (specify)
Standing dead tree 31 biotic reasons, e.g. bark beetle attack 32 abiotic reasons, e.g. drought, lightning 38 unknown cause of death 39 cause was not determined/observed
Trees that have fallen (living or dead) 41 abiotic reasons (e.g. storm) 42 biotic reasons (e.g. beavers) 48 unknown cause 49 cause was not determined/observed
Note: Class 22 is only applicable in those countries that do not record trees with more than 50% crown damage. Note: Class 23 is only applicable to those countries that restrict sampling to Kraft classes 1, 2 and 3.
Note: Mortality and the number of dead trees present in a plot are two different issues. Annual mortality can be calculated from the number of living trees that are dead the following year. The total number of dead trees in a plot at any one time provides no information on mortality rates, but provides information on the condition of a stand in the year of assessment. Note: If trees in the plot have not been mapped, there may be some difficulty in identifying the fate of individual trees that have disappeared between surveys.
44. Assessable crown (CC, C1) Class Description 1 Upper third of the crown 2 Upper half of the crown 3 Widest span of the crown is lower limit 4 Crown part without effects of competition 5 Entire crown Other (please specify and communicate to 9 data centre)
45. Social class (CC) Four classes are recognized:
Code Description 1 Dominant (including free-standing): Trees with upper crown standing above the general level of the canopy.
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2 Codominant: Trees with crowns forming the general level of the canopy. 3 Subdominant: Trees extending into the canopy and receiving some light from above, but shorter than 1 or 2. 4 Suppressed: Trees with crowns below the general level of the canopy, receiving no direct light from above. 5 Dying
Note: The assessment of the social class of a tree is in some cases difficult. Suppressed trees should not be equated with dying trees as, in a mixed-age stand, they represent future generations of trees. Classification on steep slopes presents a problem as even relatively short trees may receive direct light from above. In such cases, classification should be based on the relative heights of the trees.
46. Crown shading (CC) Crown shading is assessed on a six-point scale as follows: 1 crown significantly affected (shading or physical interactions) on one side 2 crown significantly affected (shading or physical interactions) on two sides 3 crown significantly affected (shading or physical interactions) on three sides 4 crown significantly affected (shading or physical interactions) on four sides 5 crown open-grown or with no evidence of shading effects 6 suppressed trees
47. Visibility (CC) The following codes should be used for the assessable crown: 1 Whole crown is visible 2 Crown only partially visible 3 Crown only visible with backlighting (i.e. in outline) 4 Crown not visible
Note: Class 3 is distinguished from Class 4, as some parameters can still be assessed when only back-lighting is present.
48. Defoliation (CC, C1) Defoliation is assessed in 5% steps. These classes are 0, 5 (>0-5%), 10 (>5-10%) and so on. A tree with between >95% and 100% defoliation, which is still alive, is scored as 99. The score 100 is reserved for dead trees (EC Regulation). Trees’ defoliation isshould be reported in these 5% classes: and not in aggregated groupings.
Code Description 0 0% 5 >0-5% 10 >5-10% 15 >10-15% 20 >15-20%
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25 >20-25% 30 >25-30% 35 >30-35% 40 >35-40% 45 >40-45% 50 >45-50% 55 >50-55% 60 >55-60% 65 >60-65% 70 >65-70% 75 >70-75% 80 >75-80% 85 >80-85% 90 >85-90% 95 >90-95% 99 >95-100% (alive) 100 100% (dead)
49. Foliage transparency (CC) Estimate foliage transparency in 5% classes based on the live, normally foliated portion of the crown and branches using the transparency diagram in Fig. A1-2. Dead branches, crown dieback and missing branches where foliage is expected to be missing are deleted from the estimate (Fig. IV 4A1-3).
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Fig. IV 4: Guide to estimating transparency (derived from Tallent-Halsell, 1994).
Code Description 0 0% 5 >0-5% 10 >5-10% 15 >10-15% 20 >15-20% 25 >20-25% 30 >25-30% 35 >30-35% 40 >35-40% 45 >40-45% 50 >45-50% 55 >50-55% 60 >55-60% 65 >60-65% 70 >65-70% 75 >70-75% 80 >75-80% 85 >80-85% 90 >85-90%
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95 >90-95% 99 >95-100% (alive) 100 100% (dead)
50. Flowering (CC, C1) Two assessments are made: of the assessable part of the crown and of the wholecrown. Scoring is: Code Description 1 Absent or scarce. The flowers are not seen in a cursory examination. 2 Common. Flowering effect is clearly visible. 3 Abundant. Flowering dominates the appearance of the tree.
51. Fruiting (CC, C1) As with flowering, two assessments are made: of the assessable part of the crown and of the whole crown. Scoring is: code short description 1.1 absent Fructification is absent or inconsiderable. Even reasonably lengthy observation of the crown with binoculars yielded no signs of fruiting. 1.2 scarce Sporadic occurrence of fruiting, not noticeable at first sight. It must be looked for on purpose with binoculars. 2 Common Fruting is clearly visible, can be observed with the naked eye. The appearance of the tree is influenced but not dominated by fructification. 3 Abundant Fruting dominates the appearance of the tree, immediately meets the eye, determines the tree’s appearance
1 Absent or scarce. The fruits are not seen in a cursory examination. 2 Common. Fruiting is clearly visible. 3 Abundant. Fruiting dominates the appearance of the tree.
Note: Quantitative estimates of both flowering and fruiting can be obtained by the use of litter traps. However, such data cannot be readily related to individual trees.
52. Secondary shoots and epicormics (CC) Separate assessments are made of the frequency (3 classes) of epicormics in the assessable crown and on the stem. The assessment must include all epicormics, not only the ones of the current year. Scoring is in three classes:
Code Description 1 None or rare
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2 Medium: light development or only present in parts of the crown or stem 3 Abundant: present throughout the majority of the crown or all over the stem
53. Crown form/morphology (CC) Crown form classifications have so far been developed for Picea spp., Fagus sylvatica and Pinus sylvestris. Note: the use of the Roloff classification system for species other than Fagus sylvatica must be undertaken with special care and is not recommended.
Code Tree species Description 11 Picea abies Comb 12 Picea abies Brush 13 Picea abies Plate 14 Picea abies Mix 21 Fagus sylvatica trees with vigorous growth both of apical and side shoots 22 Fagus sylvatica reduced apical shoot growth, side shoots are still formed but at lower frequency (mainly consisting of short shoots) 23 Fagus sylvatica strongly reduced apical shoot growth, no new lateral branches are formed. Shoot appearance is “claw-like” 24 Fagus sylvatica development of 23, with loss of side shoots 29 Fagus sylvatica other 31 Pinus sylvestris vigorous apical dominance with tree growing strongly upwards 32 Pinus sylvestris reduced or no apical dominance with crown showing signs of widening 33 Pinus sylvestris as 32, but lower branches being lost through suppression 34 Pinus sylvestris platform developing, with dominant growth direction no longer upwards, but crown still with some depth 35 Pinus sylvestris platform fully developed, no vertical growth 39 Pinus sylvestris other (specify)
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54. Affected part of the tree and location in crown (CC, C1) Location in crown Specification of affected part Affected part Code (optional Level I, Code (mandatory Level I and Level II) mandatory Level II) Leaves/ Current needle year 11 Upper crown 1 Leedles Older needles 12 Lower crown 2 Needles of all ages 13 Patches 3 Broadleaves (incl. evergreen spec.) 14 Total crown 4 Branches, Current year shoots 21 Upper crown 1 shoots & buds Twigs (diameter < 2 cm) 22 Lower crown 2 Branches diameter 2 – < 10 cm 23 Patches 3 Branches diameter 10 cm 24 Total crown 4 Varying size 25 Top leader shoot 26 Buds 27 Stem & collar Crown stem: main trunk or bole within 31 the crown Bole: trunk between the collar and the 32 crown Roots (exposed) and collar ( 25 cm 33 height) Whole trunk 34 Dead tree see below 04 No symptoms see below on any part of 00 tree No assessment see below 09
Special cases: The following codes for special cases shall be reported in the column for ‘specification of affected part’ of the tree: a. Dead trees: Dead trees should be reported using code 04. Defoliation score of this tree is “100”.and discolouration score is “4”.The cause of death should be reported in the column for the causal agent / factor. The death is reported in the first year when it is observed. In general, no information is submitted in the succeeding years. Only in case that in the succeeding years the reason – i.e. a biotic damage – may be found to
Page 106/178 121 be the reason for the tree’s dying, this damage should be submitted with the respective forms. b. No symptoms at all are observed on any part of the tree (no further damage parameters are assessed or submitted): In order to avoid that the observers have to report that there are no symptoms on the foliage, nor at the branches and the stem, this case should be reported using code 00. c. No assessment of damage causes was made(no further damage parameters are assessed or submitted)
Report code 09 in the column for specification of affected part.
55. Symptoms and their specification (CC, C1) Each code for
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Affected part Symptom / sign Code Symptom/sign specification Code (mandatory Level I and Level II) (optional Level I, mandatory Level II) Leaves/needles Partly or totally devoured/missing 01 holes or partly devoured/missing 31 notches (leaf/needle margins affected) 32 totally devoured/missing 33 skeletonised 34 mined 35 Premature falling 36
Light green to yellow discolouration 02 overall 37 Red to brown discolouration (incl. necrosis) 03 flecking, spots 38 Bronzing 04 marginal 39 Other colour 05 banding 40 interveinal 41 tip, apical 42 partial 43 along veins 44 microfilia (small leaves) 06 other abnormal size 07 Deformations 08 curling 45 bending 46 rolling 47 stalk twisting 48 folding 49 Galls 50 wilting 51 other deformations 52 other symptom 09 Signs of insects 10 black coverage on leaves 53 nest 54 adults, larvae, nymph, pupae, egg masses 55 Signs of fungi 11 white coverage on leaves 56 fungal fruiting bodies 57 Other signs 12 Branches devoured / missing 01 shoots& buds Broken 13 Dead / dying 14 Abortion / abscission 15 Necrosis (necrotic parts) 16 Wounds (debarking, cracks etc.) 17 debarking 58 cracks 59 other wounds 60 Resin flow (conifers) 18 Slime flux (broadleaves) 19 Decay/rot 20 Deformations 08 wilting 51 bending, drooping, curving 61 cankers 62 tumors 63 whitches broom 64 other deformations 52 other symptom 09 Signs of insects 10 boring holes, boring dust 65 nest 54 white dots or covers 66 adults, larvae, nymph, pupae, egg masses 55 Signs of fungi 11 fungal fruiting bodies 57 Other signs 12 Table A2-2: Symptoms/signs and specification of symptoms/signs; part I / II
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Affected part Symptom / sign Code Symptom/sign specification Code (mandatory Level I and Level II) (optional Level I, mandatory Level II) Stem / collar Wounds (debarking, cracks etc.) 17 debarking 58 cracks (frost cracks, …) 59 other wounds 60 Resin flow (conifers) 18 Slime flux (broadleaves) 19 Decay/rot 20 Deformations 08 cankers 62 tumors 63 Longitudinal ridges (frost ribs, …) 68 other deformations 52 tilted 21 fallen (with roots) 22 broken 13 Necrosis (necrotic parts) 16 other symptom 09 Signs of insects 10 boring holes, boring dust 65 white dots or covers 66 adults, larvae, nymph, pupae, egg masses 55 Signs of fungi 11 fungal fruiting bodies 57 yellow to orange blisters 67 Other signs 12 Table A2-2: Symptoms/signs and specification of symptoms/signs; part II / II In case that no value for symptom and/or no value for symptom specification was specified (e.g. when no assessment was done and affected part was submitted with code 09) the code "-9" should be submitted to the database in order to have a value in those key fields (see first bullet point in section "General Remarks" on key fields).
56. Age of damage (CC, C1) Code Class damage age Description
1 Fresh damage that has begun after the last year’s inventory
2 Old damage that has begun earlier
3 Fresh and old both, fresh and old damage is visible In case that no value for age of damage was specified (e.g. when no assessment was done and affected part was submitted with code 09) the code "-9" should be submitted to the database in order to have a value in this key field (see first bullet point in section "General Remarks" on key fields).
57. Causal agents/factor (CC, C1) In case that no value for age of damage was specified (e.g. when no assessment was done and affected part was submitted with code 09) the code "-9" should be submitted to the database in order to have a value in this key field (see first bullet point in section "General Remarks" on key fields).
Agent group Code Game and grazing 100 Insects 200 Fungi 300 Abiotic agents 400
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Direct action of men 500 FIRE 600 Atmospheric pollutants 700 Other factors 800 (Investigated but) unidentified 999 Table A2-3: Main categories of causal agents / factors
Agent group Code Class Code Type Code Game and grazing 100 Cervidae 110 Roe deer 111 Red deer 112 Reindeer 113 Elk/Moose (Alces alces ) 114 Other Cervidae 119 Suidae 120 Wild boar 121 Other Suidae 129 Rodentia 130 Rabbit 131 Hare 132 Squirrel etc. 133 Vole 134 Beaver 135 Other Rodentia 139 Aves 140 Tetraonidae 141 Corvidae 142 Picidae 143 Fringillidae 144 Other Aves 149 Domestic animals 150 Cattle 151 Goats 152 Sheeps 153 Other domestic 159 Other vertebrates 190 Bear 191 Other vertebrate 199 Table A2-4: Codes for agent group 100 (game and grazing)
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CONIFERS Agent Code Class Code Main species Code Affected genus Symptoms group
200 210 Acantholyda sp. Pinus Shelter made of silky threads and frass, on the needles, Finesurrounded spots with by devoured a central holeolder in needles the needles and presence Brachonyx pineti Pinus of small holes in the sheaths Devoured needles forming a thick saw edge Brachyderes suturalis Pinus
Summer defoliations. False caterpillars, greenish with Diprion pini Pinus brown - orange head. Eggs in the needle margins and pupas in the soil Silky threads in dry twigs Gelechia senticetella Juniperus, Cupressus
Defoliators Devoured needles; caterpillars with long hairs, variable Lymantria dispar Larix, Picea, Pinus yellow to black coloured with characteristic double row of blue and red spots on the back Eggs disposed in cracks of the bark. Recently born Lymantria monacha Pinus caterpillars disposed in lines in the trunk. Summer defoliations. Bupalus piniarius Pinus Choristoneura Abies murinana Cephalcia abietis Picea Cephalcia lariciphila Larix Dendrolimus pini Pinus
Boring hole with resin crumb on the trunk along with 220 Dioryctria sylvestrella Pinus sawdust and reddish excrement rests Hylobius abietis Pinus Shallow bites in thin twigs and young pines Star - shaped system of galleries under the bark . Trees Ips acuminatus Pinus damaged situated in sparce close groups. Death of trees in summer. Star - shaped system of galleries under the bark . Trees damaged situated in close groups. Death of trees in Ips sexdentatus Pinus summer. Adult is bigger than the adult Ips sexdentatus
Ips typographus Picea Bark beetle, borer, killing red spruce, dangerous for whole forest Punctures in buds and young twigs. Dry and hollow young Magdalis sp. Pinus shoots Long star - shaped system of galleries under the bark Stem, branch Orthotomicus sp. Pinus & twig borers Adults of very small size. (incl. shoot damage of larvae in part of stem with thick bark, galleries of Phaenops cyanea older larvae with 'cloudy' boring dust; beetle dark blue with miners) Pinus green glow Very small holes with resin drop resina in buds and shoots. Pissodes castaneus Pinus Galleries under the bark and pupation chambers with thick wood chips. Pityogenes Picea, Larix, Abies, chalcographus Pseudotsuga
Pityokteines curvidens Abies
Thick and big resin crumb, hollow inside, along with Retinia resinella Pinus excrements, in small branches and/or buds Galleries and pupation chambers in branches and twigs. Semanotus laurasi Juniperus
I N S E C T S C T E I N S Reddish small areas disperse in the crown. Dry and hollow apical twigs. Resin crumb in trunk with a Tomicus destruens Pinus hole for entering. Under bark galleries with shape of fish thorns. Death of the trees in spring.
Bud boring 230 Rhyacionia buoliana Pinus Hollow buds and young shoots (bayonet shaped shoots), Hollowalong with buds resin and crumbs. young shoots (bayonet shaped shoots), insects Rhyacionia duplana Pinus along without resin crumbs.
240 Irregular shaped boring holes filled with resin in the fruit Dioryctria mendacella Pinus (pine cones). Presence of galleries with excrements and Fruit boring silky threads. insects Round and clean boring holes in the pine cones. Egg - Pissodes validirostris Pinus layings are covered with a dark stopper and disposed in the pine cone scales
Haematoloma 250 Pinus, Juniperus Eggs - laying in shape of a "spit" over grasses. Reddened dorsatum needles. Suking Adults with eliptic white bodies (like white scales stucked to Leucaspis pini Pinus insects the needles). Breakage and formation of scales in stems. Adults with Matsucoccus sp. Pinus eliptic sessile bodies under the bark.
Mining 260 Brown and curved needle in part of its length, with a boring Epinotia subsequana Abies hole. insects
Gallmakers 270
Other insects 290 Table A2-5: Codes for agent group 200 (insects): Conifers
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BROADLEAVES
Agent Code Class Code Main species Code Affected genus Symptoms group
200 210 Abraxas pantaria Fraxinus It attacks leaves during the summer. Caterpillars let themselves down from the crown by means of silky threads
Agelastica alni Alnus Leaves are skeletonized and devoured irregularly. Eggs are yellow and the egg - laying is over the leaf. Altica quercetorum Quercus Leaves look brown due to the skeletonizing. Epirrita autumnata Betula leaves devoured Galerucela linneola Populus, Salix Leaves skeletonized with the veins intact and damages in buds. Eggs - layings in the back side of the leaf.
Gonipterus scutellatus Eucalyptus Leaves devoured, with margins looking as narrow and deep saw teeth Leucoma salicis Populus, Salix, Betula White eggs - layings in trunks and branches. Lymantria dispar Quercus Attacks the current year leaves and in extreme cases also the older ones. Eggs - laying look like yellow mass and are Archips xylosteana Quercus Attacksdisposed the in tipsheltered of the current areas ofyear trunk shoots. and thick Shelter branches. is made Defoliators with young leaves tied toghether by means of silk threads. (incl. skeletonizers, Lymantria monacha Quercus, Fagus, Betula u.a. Greyish caterpillar. leaf rollers etc.) Melolontha spec. Quercus u.a. Operophthera brumata Quercus
Operophthera fagata Fagus
Thaumetopoea Quercus processionea Melasoma populi = Populus, Salix Leaves devoured starting from the margins and /or in holes. Chrysomela populi Orange eggs - laying over the leaf. Very typical larvae (easy to recognise) Tortrix viridana Quercus Attacks the current year shoot tips. Makes a shelter with young leaves tied toghether by means of silky threads. Greenish caterpillar, they let themseves down by means of silky threads. Xanthogaleruca luteola Ulmus Leaves look brown due to skeletonizing.
220 Agrilus grandiceps Quercus Death of thin twigs as it is a twig girdler - galleries . Circular exit holes Cerambyx sp. Quercus Big eliptic holes at the base of the trunk and thick branches through which sawdust flows. Big sized galleries
Coroebus florentinus Quercus Death of small and median sized branches. Death of twigs due to twid girdling (galleries) Tha damage looks like red flashes distributed all along the crown Agrilus biguttatus Quercus
Agrilus viridis Fagus
Stem, branch Crematogaster Quercus Great number of small holes in the cork. Ants. & twig borers scutellaris (incl. shoot Cryptorrhynchus Populus, Salix Circular holes in the trunk trough which small wood chips miners) lapathi flow. Superficial girdling damages. Melanophila picta Populus Debarking and eliptic holes with a compact dark brown coloured detritus at the base of the trunk.
I N S E C T S Paranthrene Populus, Salix Circular holes in the trunk through which flows round wood tabaniformis chips Rests of the chrysalis in the hole. Affects to young Phoracantha Eucalyptus Elipticplants holes(10-15 in cm the of trunk. dbh) Wide galleries under the bark. semipunctata Platipus cylindrus Quercus Circular holes in the trunk through wich flows sawdust , which is acumulated at the base of the trunk. Sesia apiformis Populus, Salix Circular holes at the base of the trunk and chrysalid cocoons made of sawdust. Affects to trees of more than 10 - 15 centimetres of dbh
Bud boring 230 insects
Fruit boring 240 Curculio glandium Quercus Boring holes in the acorns insects
Ctenaritaina eucalypti Eucalyptus Small aphids over young shoots. Bent shoots and sap fluxes Sucking 250 insects Kermes sp. Quercus Spherical bodies covered by a brilliant black reddish wax cover, situated in the stalks insertion areas of leaves, buds or branch axils. Mining Rhynchaenus fagi Fagus Many small holes in the leaf, it mines the leaf starting from the central vein to the margins insects 260
270 Cynips tozae Quercus Big spherical greyish - brown galls with a crown of teeth on the top, in small branches or twigs. Gallmakers Dryomyia lischtensteini Quercus Hemispheric or irregular shaped swellings at the back side Mikiola fagi Fagus Smallof the pinkleaf. galls with a shape like waters drops, on the leaf
Other insects 290 Table A2-6: Codes for agent group 200 (insects): Broadleaves
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CONIFERS Agent Code Class Code Main species Code Affected genus Symptoms 300 Needle casts 301 Lophodermium pini = Pinus Long brilliant black carpophores located on the upper needle surface and needle- rust Leptostroma pinostri fungi Lophodermium sulcigena Pinus sp. Cyclaneusma minus = Pinus (Sylvestris, Formation of traverse reddish brown stripes (banding) and presence of elliptic Naemacyclus minor radiata) carpophores (ligth brown or the same colour than the needle) Phaeocryptopus gaeumannii Pseudotsuga
Rhabdocline pseudotsugae Pseudotsuga
Mycosphaerella laricina Larix Naemacyclus nivens Pinus Ligth coloured carpophores. When they come off, they leave holes in the needles. Thyriopsis halepensis Pinus Needles with circular black carpophores with brown centre. Mycospherella pini = Pinus (radiata, It is the so called "red banding" in needles F Dothistroma septospora nigra, halepensis) Chrysomyxa abietis Picea yellow to orange-brown spots on needles which fall prematurely U Stem and shoot 302 Melampsora pinitorqua Pinus Shoots are curved in shape of "C" or "S". To complete its biological cycle rusts needs host trees pertaining to Populus and/or Pinus genus Cronartium ribicola Pinus strobus N Coleosporium tussilaginis = Pinus "Blister rust" of the needles. Blisters are orange when full and white when Coleosporium senecionis empty. Cronartium flaccidum = Pinus "Blister rust" of the bark. Girdling of the branches or trunk with abundant resin G Peridermium pini flows. Blisters are orange when full and white when empty. Dieback and 309 Gremmeniela abietina Pinus Death of branches and buds with black carpophores over the bark. When it canker fungi ripens pink pendants with conidia go out. I Cenangium ferruginosum Pinus Death of branches and buds. Black carpophores over the bark Blight 303 Shaeropsis sapinea = Pinus Side shoots are curved, presenting deformations, resin flows and black Diplodia pinea carpophores. Sirococcus conigenus Pinus (halepensis) Death of shoots and reddish brown hanging needles.
Decay & root 304 Fomes pini = Trametes pini Pinus Flat woody carpophores with "horse hoofs" shape, greyish brown rot fungi Amillaria mellea many tree species White leather cover visible when debarking roots and root collar, goes up. Forms honey coloured mushrooms with foot, in small groups
Heterobasidion annosum Abies, Pinus, Picea, White leather cover but less dense than the one from Armillaria visible when Larix, Pseudotsuga debarking the root or root collar. Mushrooms are greyish brown with white margins and they are stuck to the root collar surface Other fungi 390
BROADLEAVES Agent Code Class Code Main species Code Affected genus Symptoms 300 Leaf Spot fungi 305 Drepanopeziza punctiformis = Populus, Salix Small round spots, with brown margins and greyish white centre. marssonina brunea Rhytisma spp Salix, Acer Big black irregularly- shaped scabby spots Taphrina aurea Populus Yellowish swellings or bumps Mycosphaerella maculiformis Castanea Chestnut rust. Reddish brown dots distributed all along the leaf Septoria populi Populus Grey spots limited by a necrotic margin Harknessia eucalypti Eucalyptus Reddish brown irregular spots Mycosphaerella eucalypti Eucalyptus Red spots Anthracnose 306 Apiognomonia spp. Quercus, Juglans Affects to the veins Powdery 307 Uncinula spp. Populus, Salix, Greyish white powder over buds and/or leaves (oidium) mildew Microsphaera alphitoides QuercusUlmus White powder over the leaves (oidium) Wilt 308 Ophiostoma novo - ulmi Ulmus Shoots and buds wilt, when cutting the buds and thin branches you can see a necrotic ring which corresponds to the vascular collapsing Ceratocystis fagacearum Quercus Venturia populina = Pollaccia Populus leaves are brown coloured and curved by the stalk elegans Rust Mellampsora allii - populina Populus Yellow to orange dots in the back side of the leaf F 302 Melampsoridium betulinum Betula rapidly multiplying small spots on leaves which fall prematurely U Blight 303 Botryosphaeria stevensii = Quercus Dry and curved shoots (dieback) with necrosed bark and longitudinal cracks Diplodia mutila where the carpophores appear N Hypoxilon mediterraneum Quercus The bark comes off, showing plates, in trunk and branches Fusicoccum quercus Quercus Dothichiza populea Populus Black carpophores in buds and branches bark G Canker 309 Cryphonectria parasitica = Castanea Yellowish leather cover (triangle shaped) under the cracks of the bark Endothiella parasitica Pezicula cinnamomea Quercus I Stereum rugosum Quercus, Fagus Cytospora crysosperma= Populus Orange carpophores over the bark valsa sordida Nectria spp. Quercus Red carpophores under the bark cracks Decay & Root 304 Fomes fomentarius Fagus Flat woody carpophores with a "horse hoofs" shape. The upper part has a rot concentric flat area greyish brown coloured Ganoderma applanatum Fagus Flat woody carpophores with a "horse hoofs" shape. The upper part is covered by a reddish brown powder Ungulina marginata Fagus Flat woody carpophores with a "horse hoofs" shape. The upper part is reddish brown with yellowish margins and the bottom part is yellowish.
Amillaria mellea many tree species Phytophthora spec. Alnus, Castanea, Black spot with jagged margins under the bark and blackish flows Quercus, Betula, Fagus Deformations 310 Taphrina kruchii Quercus Witches broom, with many buds presenting chlorotic and abnoramlly small sized leaves Other fungi 390 Table A2-7: Codes for agent group 300 (fungi)
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CONIFERS/BROADLEAVES Agent Code Class Code Type Code Specific factor Code Symptoms group 400 Chemical factors 410 Nutritional disorders- 411 Cu - deficiency 41101 nutrient deficiencies
Fe - deficiency 41102 Mg - deficiency 41103 Mn - deficiency 41104 K - deficiency 41105 N - deficiency 41106 B-deficiency 41107 Mn - toxicity 41108 A Other 41109 marine salt + 412 B surfactants Physical factors 420 Avalanche 421
Drought I 422 Flooding /High 423 water O Frost 424 Winter frost 42401
Late frost 42402 T Hail 425 Heat /Sun scald 426 I Ligthning 427 Mud/ land slide 429 C Snow /Ice 430 Wind/ Tornado 431 Winter injury - 432 winter desiccation
Shallow/ poor soil 433
Rock fall 434 Other abiotic factor 490 Table A2-8: Codes for the agent group 400 (abiotic factors).
Agent group Code Class Code Type Code Symptoms Direct action of 500 Imbedded 510 men objects Improper 520 planting technique Land use 530 conversion Silvicultural 540 Cuts 541 operations or Pruning 542 forest harvesting Resin tapping 543 Cork stripping 544 Silvicultural operations in close trees and other 545 silvicultural operations Mechanical/ 550 vehicle damage Road 560 construction
Soil 570 compaction Improper use 580 Pesticides 546, 581 of chemicals
Deicing salt 547, 582 Other direct 590 action of men
Table A2-9: Codes for the agent group 500 (direct action of man).
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Agent group Code Class Code
Atmospheric 700 SO2 701 pollutants H2S 702 O3 703 PAN 704 F 705 HF 706 Other 790 Table A2-10: Codes for the agent group 700 (atmospheric pollutants).
Agent Code Class Code Species/Type Code Affected Symptoms group genus Other 800 Parasitic/Epiphytic/ 810 Viscum album 81001 conifers, Climbing plants broadleaves
Arceuthobium 81002 Juniperus oxycedri Hedera helix 81003 All sps Lonicera sp 81004 All sps Clematis spp 81005 All sps Clematis vitalba 81006 All sps Loranthus 81007 Quercus europaeus Humulus lupulus 81008 All sps Vitis vinifera ssp 81009 All sps sylvestris Bacteria 820 Bacillus vuilemini 82001 Pinus Swellings of different sizes in halepensis branches and branchlets Brenneria quercinea 82002 Quercus Slime flux in fruits Virus 830 Nematodes 840 Bursaphelenchus 84001 Pinus fast reddening of the crown and xylophilus sudden death of the tree Competition 850 Lack of ligth 85001 Physical 85002 interactions Competition in 85003 general (density) Other 85004 Somatic mutations 860 Mites 870 Eriophyes ilicis 87001 Quercus Areas with abundant reddish brown hair at the backside of the leaf Other (known cause 890 but not included in the list) Table A2-11: Codes for the agent group 800 (other)
58. Scientific name of cause (CC, C1) If the organism involved can be identified the scientific name must be reported, using the codes of 7 letters. As a general rule the codes consist of the first 4 letters of the Genus name, followed by the first 3 letters of the species name (e.g. Lophodermium seditiosum = LOPHSED). If the Genus name has only 3 letters, these are followed by the first 4 letters of the species name (e.g. Ips typographus = IPSTYPO). Codes for the most common damaging species are listed in the internet file http://icp-forests.net/page/ad- hoc-group-on-assessment-of>> click on annex 3. This table also provides information on synonyms and tree species on which the damaging agents occur most frequently. In case that no scientific name of case is specified (e.g. when no assessment was done and affected part was submitted with code 09) the code "-9" should be submitted to the database in order to have a value in this key field (see first bullet point in section "General Remarks" on key fields).
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The following sources of information provide information for the field observers to facilitate the diagnosis: Tables A2-3 – A2-11 contain the coding system for damaging agents. Especially the sheets on insects and fungi provide information about specific symptoms caused by a selection of relevant organisms. http://www.icp-forests.org/WGbiotic.htm>> click on Annex 3, provides codes for the scientific names of causal agents. http://www.icp-forests.org/WGbiotic.htm>> click on Annex 4, provides examples, descriptions and photographs of damage caused by important categories of insects and fungi. http://www.icp-forests.org/WGbiotic.htm>> click on Annex 5, provides a key with symptoms linked to frequently occurring damage causes. However keep in mind that these are possible damage causes, other factors may cause similar symptoms. Diagnosis should always be confirmed by an expert phytopathologist whenever possible.
59. Extent classes (CC, C1) The damage extent will be reported in the following classes:
Code Description 0 0 % 1 1 – 10 % 2 11 – 20 % 3 21 – 40 % 4 41 – 60 % 5 61 – 80 % 6 81 – 99 % 7 100 %
60. Diameter at breast height (DBH) (GR, G1) The diameter at breast height (1.30 m) over bark in 0.1 centimetres. When a diameter tape is used a single value will be needed. When calipers are used the maximum and the minimum diameter (over bark) shall be determined and reported (diameter 1 and diameter 2).
61. Bark (GR, G1) The thickness of the bark at 1.30 m, expressed in centimetres with one decimal (e.g. “2.1” means “2 cm and 1mm” or “2.1 cm”).
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62. Tree Height (GR, G1) The height of the tree expressed in metres rounded to an accuracy of 0.1 metres.
63. Tree Volume (GR, G1) Based on the measured diameter(s) and height, the tree volume can be estimated using locally known form factors or through the use of valid volume tables. The tree volume shall be expressed in cubic metres (m³) with three decimals. The formula used to compute tree volume and the minimum diameter used for the volume calculation should be reported in the data accompanying form.
64. Height to crown base rounded to the nearest 0.1 meters (GR, G1) The height (length) of the crown rounded to the nearest 0.1 metres is determined from the tip of the highest stem tip to the junction of the lowest live branch excluding water shoots.
65. Crownwidth rounded to the nearest 0.1 meters (GR, G1) The average crown width is determined by the average of at least four crown radii, multipled by two, and rounded to the nearest 0.1 metres.
66. Diameter under bark (GR, G1) The actual diameter under bark is calculated as the diameter over bark deducted with the width of the bark at the two sides. The diameter under bark of five years ago is calculated as the actual diameter under bark less the increment of the last five years of the tree at both sides. The diameter under bark is expressed in centimeters rounded to one decimal: 0.1 centimetres.
67. Basal area per hectare (GR) The actual basal area per plot is calculated as the total basal areas of all the trees in the plot expanded or reduced to one hectare. Basal area per hectare is expressed in m² rounded to one decimal: 0.1 m2.
68. Volume per hectare (GR) The actual volume per plot is calculated as the total volume of all the trees in the plot expanded or reduced to one hectare. Volume per hectare is expressed in m³ rounded to one decimal: 0.1 m3.
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69. Thinning (GR) If a thinning has taken place in the five-year period between the two years of determination of diameter, basal area per plot and volume per plot, this will be indicated (Yes = 1, No = 0). In an additional part the details of this thinning may be described as detailed as possible (including: thinning method, exact year of thinning, thinning intensity expressed as number of trees, basal area/ha, volume/ha).
70. Tree species group (GR) In stands with only one tree species the tree species code is submitted using the code specified in explanatory item (43). In case of more tree species on the growth plot the most frequent tree species should be submitted in distinct rows/lines of the INV file/form. Less frequent tree species may be neglected or incorporated to one of the main tree species. In this case, please note respective tree species in the field
71. Number of trees (GR) All trees (shoots) from 5 (3) cm (DBH) and more are counted.
72. Basal area mean tree (GR) Basal area is defined as the area per hectare (usually expressed in m²) which is built by all trees standing on one hectare measured at a height of 1.3 m. The basal area mean tree is defined by its dbh and its height as follows: Diameter of basal area mean tree (quadratic mean diameter): Is calculated from the arithmetric mean of the basal area of all trees (or species specific) or directly from the square root of mean quadratic diameter. Height of basal area mean tree (height of quadratic mean diameter): Is derived as the height from a diameter-height function coresponding to the basal area mean tree diameter.
73. Top height (GR) Top height is little affected by thinning under most thinning regimes, therefore it is a more practical parameter than stand mean height for classifying growing condition (site quality, yield class). There are two common ways to determine top height: Defined by a number of largest trees (field
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Current practice is to determine the 100 trees per hectare (or less if growth plot is smaller) of largest dbh to calculate the mean basal area diameter of this sample (72) and to derive the coresponding height from a diameter-height function. Defined by a percentage of largest trees (field
74. Growth data quality code (GR, G1) code Description 0 No data, thus no information on check procedures 1 Raw data without any quality checking after measurement 2 Data checked and qualified to be correct 3 Data checked and found to be outside plausible range; not corrected 4 Data checked and found to be inconsistent with other measures from same assessment (h/d-ratio, ...); not corrected 5 Data checked and found to be inconsistent with the same measure from other assessments (negative increment, ...); not corrected 6 data checked and found to be outside plausible range; corrected 7 data checked and found to be inconsistent with other measurements from same assessment (h/d-ratio, …); corrected 8 data checked and found to be inconsistent with the same measurement from other assessments (negative increment, ...); corrected 9 data not measured but estimated
75. Number of all standing trees (GR, G1) The total number of trees (shoots in coppice forests) in the growth plot. All trees (shoots) from 5 (3) cm (DBH) and more are counted. The trees must be living or have recently died.
76. Status, removals and mortality (GR, G1) Tree alive and diameter or circumference measurable (note this is different than a missing value) 01 tree alive, in current and previous inventory (formerly blank) 02 new alive tree (ingrowth)
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03 alive tree (present but not assessed in previous inventory) 04 alive tree but tree not longer in growth sample due to heavy disturbances (e.g. heavy storm damage) 07 no info on this tree with this submission (e.g. tree forgotten during field work) 08 alive tree but due to alternating tree selection not in submitted sample Tree removed, disappeared 11 planned utilization 12 utilization for biotic reason 13 utilization for abiotic reason 14 cut, stump found butreason unknown 18 reason for disappearance unknown 19 reason for disappearance not determined/observed Tree still alive and standing, but no tree crown measurements taken or height measurements should not be used in stand or growth calculations. 21 lop-sided or hanging tree 24 breakage of the tip(s) or part of crown brokenof the tree (shoot) 25 tree not in height growth sample 29 other reasons, specify Standing dead (at least 1.3 m in height) 31 tree with intact crown, biotic reason 32 tree with intact crown, abiotic reason 33 crown breakage 34 stem breakage, below crown base and above 1.3 m 38 tree with intact crown, unknown cause of death 39 cause was not determined/observed Fallen alive or dead, (height below 1.3 m or tree stem or crown touches the ground at one place) 41 abiotic reasons 42 biotic reasons 48 unknown cause 49 cause was not determined/observed In cases that more than one remark is needed, chose the most important remark and explain the second remark in the comment column: for example a loop-sided ingrowth tree without height measurements would receive the code 21 – as no concerning data will be submitted and comments 02: ingrowth tree.
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77. Measurement or Average Value (GR) Code Survey 1 Measurement 2 Average value
78. Continuous dentrometer or girthband (GR) code Survey 1.1 Point dendrometer 1.2 Circumference dendrometer 2 Girthband measurement
79. Event (PH) Code Description 1 Flushing 2 Colour changes 3 Leaf/needle fall 4 Leaf or crown damage 5 Other damage 6 Lammas shoots / secondary flushing 7 Flowering
80. Installation date – Pheno tree selection (PH) Date at which the trees for phenology monitoring were selected and the visible part of the crown and the observation direction were defined.
81. Code for visible part of crown (PH) code description 1 top of the crown visible 2 middle of the crown visible top and the middle of the crown 3 visible 4 The whole crown
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82. Direction FROM where observations are made (PH) Code Description 1 North 2 North-east 3 East 4 South-east 5 South 6 South-west 7 West 8 North-west
83. Vertical direction FROM where the observations are made (PH) Code Description 1 From below 2 At crown level 3 From above
84. Score of event (PH) The score gives the relative share of affected tree compartments of the observed crown in case of intensive survey. In case of observation on plot level it is the proportion of the forest crown affected.
Code Description score All events but flowering and damage: 1 <1% 2 Infrequent or slight 1 – 33% 3 Common or moderate >33 – 66% 4 Abundant or severe >66% – 99% 5 >99% Codes for flowering and damage events: 6 Flowering / Damage absent 7 Flowering / Damage present Codes for flowering events (optional quantification): 7.1 Flowering sparse (optional) 7.2 Flowering moderate (optional)
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Code Description score 7.3 Flowering abundant or mast (optional)
85. Method used for making the observation (PH) Code Description 1 field observation 2 digital camera 3 both field observation and digital camera
86. Name of submitted digital image files (PH, LAI, OZ) The name is built from the code of the country as described in Explanatory item (1), four digits for the plot number (2), and 6 digits for date of observation (3). In case of a photo this would read e.g. “040534000114050913541301.jpg”. In case that more than one tree is observed by a movie, as many records (lines) in the submission file .PHD are to be submitted as the number of observed trees is (see example below). Name of image will be for submission: XXPPPPNNNNDDDDDDTTTTTTSS.jpg or in case of Ozone: XXPPPPNNN.NNN.NNN.NDDDDDDTTTTTTSS.jpg X – country code (ICP Forests manual, Expl. Item (1)) P – plot number (ICP Forests manual, Expl. Item (2)); "9" and 3 further letters for assigning a location not being a ICP Forests / FutMon plot N – measurement point number (LAI Field Protocol) or tree number (Pheno; Expl. Item (41))or in case of Ozone photos species code (13 digits instead of only 4) followed by “.1” in case of ozone damage and “.0” in case of no ozone damage observed. Use 9999 in case that plot representative image or image which is relevant on more than one trees, respectively, is submitted. D – date of image production (DayMonthYear, DDMMYY: e.g. 140509) T – time of image production (HHMMSS) Sequence number (01, 02, 03,.) to indicate which photo in a respective time. Example: Country Germany, Plot 534, observation from 14th of May 2009, Trees number 2, 5, 6, 8, 10, 12, 15, 16, 19, and 20 were observed with a movie in format .m2v leads to the following name of the movie: 040534000214050913541301.m2v for file .PHD: The respective lines in the .PHD should be ("camera type 1" example for
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00454 0534 05 020 07040534000514050913541301.m2v camera type 1 00455 0534 06 020 07040534000614050913541301.m2v camera type 1 00456 0534 08 020 07040534000814050913541301.m2v camera type 1 00457 0534 10 020 07040534001014050913541301.m2v camera type 1 00458 0534 12 020 07040534001214050913541301.m2v camera type 1 00459 0534 15 020 07040534001514050913541301.m2v camera type 1 00460 0534 16 020 07040534001614050913541301.m2v camera type 1 00461 0534 19 020 07040534001914050913541301.m2v camera type 1 00462 0534 20 020 07040534002014050913541301.m2v camera type 1 … (further records / lines if needed)
87. Sample_ID (GV) For each sampling unit (inside outside fence, CSA, etc) use an unique ID, which must not change over time. If you have already a unique number for each subplot and you have submitted this until the monitoring year 2010 as ‘Survey number’use this number as new Sample_ID and note it in the ‘other observations as “old survey number”. The Sample_ID must be identical on both PLV and VEM forms. By combining the plot number with the Sample_ID and the survey number a unique plot/survey number is created. For the species occurring on remaining plot use an own Sample_ID. Note: With the old coding system (only Survey number) it was not possible to code that e.g. two assessments within one year (Spring and Summer) were made on the same subplot.
88. Team_ID (GV, PH, C1, CC) Each field crew which is responsible for the assessment should have an ID which must be unique and must not change over time. National Focal Centres need to maintain lists that link Team_ID with real names of experts
89. Number of team members (GV) Indicate the number of persons the field crew of the defined team consists.
90. Survey type (GV) Indicate the type of the Ground vegetation survey. Code Type
1 CSA (Common Sample Area); 400m²
2 SSA (Standardized Sampling Area) (each 100m²)
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3 Addional Species List of CSA (2100m²)
4 Other (e.g. for population studies)
91. Survey number (GV) Each time (day), or situation (inside outside fence), that an assessment of ground vegetation is made on a given subplot (coded by the sample_ID), a survey number is given (identical on both PLV and VEM forms). By combining the plot number with the sample_ID and the survey number a unique plot/survey number is created. Example: A spring and a summer assessment on a Sublot should be submitted as follows: PLV !Sequence, country, plot, sample_ID, team_ID, no_members, survey_type, survey_nr, date,... 0001 04 0001 01 01 2 1 01 250312 ... 0001 04 0001 01 01 2 1 02 140612 ...
92. Fencing_GV (GV) As the vegetation can be very different inside and outside a fence, it was decided that in principle the ground vegetation is surveyed always outside the fence. In case that also inside the fence a survey is carried out this should be reported as a separate survey and the fencing code be indicated: 1 Yes, survey within the fence 2 No, survey was done outside fenced area.
93. Total sampled area (GV) The total sampled area (CSA) shall be 400 m2. Sampled areas of all other surveys, which have an own Sample_ID should be specified too. In the Data Accompanying Report the exact details of the number of repetitions and the location/orientation of the ground vegetation plots shall be given.
94. Height and cover of layers (GV) The estimated cover of the tree layer, the shrub layer, the herb layer and the moss layer shall be submitted as % of the total sampled area. The estimated cover of bare soil and litter shall be submitted as separate “layers” as % of the total sampled area (effective surfaces covered by visible mineral soil and rocks
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and visible litter (even if under shrubs, herbs or trees). The submission is done using up to 4 digits for cover values with a floating decimal separator (between 0.01 and 9999). The average height of the layers shall be given in meters using up to 4 digits height (in m) cover (in %) Tree layer ======x Shrub layer x x Herb layer x x Moss layer ======x Bare soil “layer” ======x Litter “layer” ======x
95. Layers (GV) The following layers are defined.
Code Layer
1 Tree layer (only ligneous and all climbers) > 5 m height
2 Shrub layer (only ligneous an all climbers) > 0.5 m height
3 Herb layer (all non-ligneous, and ligneous < 0.5m height)
4 Moss layer (i.e. terricolous bryophytes and lichens)
96. Substrate type (GV) The following substates species could grow on are:
Code Substrate type
1 Terricolous
2 Deadwood
21 Deadwood, standing trees
22 Deadwood, lying trees
23 Deadwood, stumps/snags
24 Deadwood, other (e.g branches)
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3 Bedrocks, boulder, stones
4 Epiphytic on living trees
41 Epiphytic on living trees, prevailing on roots
42 Epiphytic on living trees, prevailing at stem
43 Epiphytic on living trees, prevailing in crown
44 Epiphytic on non-ligneous plants
5 Water suface
6 Submerged
7 Anthropogenic/artificial surfaces
8 Other
The standard assessment of the ground vegetation assessment takes into account all terricolous species (Code 1). All non-terricoulous species can be noted addionally.
97. Species code (GV) The species code exists of the code for the family (999), the code for the genus (999), the code for the species (999). Family, genus, and species codes are separated by a dot (“.”). Determination at Genus level, using ‘999’ as the code for sp/spp (‘species pluralis’), is the minimal submission requirement; the “Other observations” text field should be used for additional information (e.g. if there are obvious more than one unknown species of the same Genus within the plot). The coded lists for vascular plants and cryptogams are available via the internet page of the responsible Expert Panel of ICP Forests (http://www.icp-http://icp- forests.net/page/expert-panel-on-biodiversity). In case that species will occur that are not included on this list, the National Focal Centre will take contact with the Expert Panel prior to the formal data submission to the European data centre. The Expert Panel will assign a new (999.999.999) code and include it on the list available on the internet. The new species will be submitted to the European data centre with the new code. An additional list of nationally important or problematic species can be prepared and maintained by the NFC if regarded necessary.
98. Cover of plant species (GV) Countries are free in the assessment of the abundance/cover of the plant species. The submission of this cover is done in % using up to 5 digits with a floating decimal separator (between .0001, 99.99 and 100.0). In the DAR the complete assessment methods, as well as the adopted conversion to % shall be specified.
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99. Certainty of species determination (GV) Information about the certainty of the species determination should be given. The subspecies and/or the variant should be specified in “other observation”. Apart from aspects of quality assurance, this enables to transfer national addional information like subspecies, variant or cf. (species determination is uncertain). Also for questions of species richness it is important to know if species which could be only determined on genus level (Genus sp.) are certainly different from those which are already part of the species list of the respective survey. In practice, the majority of species records are assigned to Certainty code “5”. Please use the following codes:
Code Descripion
1 Uncertain on species level, species could be same than already listed species in the survey (Genus sp.). Species code ends with ‘.999’.
2 Uncertain on species level, but certain that species is different to listed species of same genus (Genus sp.). Species code ends with ‘.999’.
3 cf., uncertain on species level, but very likely the specified species (Genus cf. species).
4 agg./x: aggregated species/hybrids: Species determination/taxonomic ranking is rather complicate due to hybridization among several recognized species and/or apomictic plants (e.g. Taraxacum officinale agg. / group).
5 Certain on species level.
6 Certain on species level, but uncertain on subspecies level (Genus species cf. subspecies). Specify subspecies in other observations.
7 Certain on subspecies level (Genus speciessubspecies). Specify subspecies in other observations).
8 Certain on variant level (Genus speciessubspecies variety). Specify subspecies and variety in other observations). Note: In cases of uncertainity on species level (Genus sp.) it is for reasons of data integrity not possible to submit more than one record per certainty class for the same Genus.
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100. Survey type (OZ) Code Description LTF Ozone injury assessment on main tree species at Intensive Monitoring Plot (requires to submit a LTF form) LSS Ozone injury assessment on LESS plots (requires to submit a LSS form) OTS Ozone injury assessment on other symptomatic species outside the LESS plots (requires to submit a OTS form)
101. Soil moisture (OZ) Code Description 1 Wet or damp (riparian zones and wet or damp areas along a stream, meadow or bottom land) 2 Moderately dry (grassland or meadow, or North or East facing slopes) 3 Very dry (exposed rocky edges)
102. Percentage of symptomatic leaves (OZ) Percentage of symptomatic leaves for actual year's leaves or needles (C), and the needles of last year (C+1) in code. Code Description 0 No injury, none of the leaves or needles injured 1 In broadleaves, 1%-5% of the leaves show ozone symptoms; in conifers, 1%-5% of the needle surface is affected 2 In broadleaves, 6%-50% of the leaves show ozone symptoms; in conifers, 6%-50% of the needle surface is affected 3 In broadleaves, 51-100% of the leaves show ozone symptoms; in conifers, 51-100% of the needle surface is affected.
103. Sample sizes at specified precision level (OZ) Precision Level "10" or "20"is to be submitted with form PLL.
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Adjusted sample size Length of the light Possible 2x1 m non (FPC adjusted), exposed forest edge. overlapping 10% error quadrates code: 10 10 5 5 15 8 7 20 10 9 25 13 11 30 15 13 35 18 15 40 20 17 45 23 18 50 25 20 60 30 23 70 35 26 80 40 28 90 45 31 100 50 33 150 75 42 200 100 49 250 125 54 300 150 59 350 175 62 400 200 65 450 225 67 500 250 69 600 300 73 700 350 75 800 400 77 900 450 79 1000 500 81 2000 1000 88
104. Validation status (OZ)
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Code Description NR Not revised. Material was not sent to the validation center for validation Y Sent to the validation centre, which confirmed that the symptoms were produced by ozone N Sent to the validation centre, which confirmed that the symptoms were not produced by ozone
105. Type of validation (OZ) The ozone symptom has been validated by the validation centre based on: Code Description L Leaves M Microscopy P Photos LP Leaves and photos LM Leaves and microscopy MP Microscopy and photos LMP Leaves, microscopy and photos
106. Quadrat number (OZ) This field is used to identify the assessments of ozone injury at each single rectangle (quadrat). Number the different rectangles (quadrats) progressively. E.g., if 10 rectangles (quadrats) are assessed, this field is used to identify rectangles 1, 2, 3….10. If a rectangle is without any plant for ozone assessment (e.g. a gap, skidder trail, rock) the number of the
107. Woody/non woody (OZ) code Survey P Perennial A Annual W woody
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code Survey N non – woody
108. Instrument number (MM) All instruments that are installed in or near the plot are given an unique instrument number which must not change over time. When instruments are replaced or added, new codes are applied (e.g. the fifth instrument in plot 3426 will thus receive instrument number 5. From data submission year 2011 onwards the plot number and the instrument number are submitted in two distinct fields. Instrument numbers should be directly transferred from the old numbering before the year 2010. If this is not be possible, please indicate this in the field
109. Location (MM) The location of the instrument is indicated: Code Location of the instrument instrument is located on site, i.e. in (the bufferzone) of the plot. This could be S under the canopy, above the canopy or in the forest soil. F instrument is located in a (nearby) open field in the forest area. W instrument is located at a weather station (in general outside the forest area). O instrument is located somewhere else.
110. Variable (MM) Indication of the variable that is measured with the instrument Aggregation Forms Code Variable measured Unit Sum Mean** Min Max Daily Hourly AT Air temperature °C X X X MEM MEH Total precipitation PR mm X MEM MEH including snow, etc. RH Relative humidity % X X X MEM MEH WS Wind speed m/s X X MEM MEH angular WD Wind direction* X MEM MEH degree SR Global radiation W/m² X MEM MEH UR UV b radiation X MEO MEH TF Throughfall ( mm X MEO MEH
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Aggregation Forms Code Variable measured Unit Sum Mean** Min Max Daily Hourly SF Stemflow mm X MEO MEH ST Soil temperature °C X X X MEO MEH Matric potential in MP hPa X X X MEO MEH the soil Water content in the WC Vol % X X X MEO MEH soil Other codes for additional variables may be used, but should be specified in the DAR-Q; code XX to be specified with MEO MEH data base management before submission
* The windrose will be split into 12 sections of 30o starting from 15o onwards. The most frequent wind direction is reported by its middle value e.g.: 30 o = the sector 15 o -45 o, 60 o for the sector 45 o -75 o, 90 o for the sector 75 o -105 o, etc.)
**arithmetic average of all values from the period, with the exception for the prevailing wind direction where the most frequent section is meant
111. Instrument information (MM) Vertical position The vertical position (height or depth) of the instruments shall be indicated in meters with a plus (=height above the ground) or a minus sign (depth below the ground).
Recording code The following codes shall be used for the samplers and recording method of data: Samplers and recording method of data Code Manual reading and recording on paper 10 Mechanical recording (manual reading and recording on paper) 20 Direct paper recording 30 Digital recording (in stand alone situation) 40 Digital recording (integrated datalogger) 50
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Details on the equipment shall be stated in the Data Accompanying Report.
Scanning interval Scanning interval in seconds (automatic instruments only).
Storing interval The interval between two consecutive data storage moments shall be stated in minutes.
112. Completeness (MM) The completeness is an indicator of the coverage of the scanning and storing procedures and is stated in % of measurements that should have been recorded (e.g. for daily values with a storing interval of 15 minutes there should be 96 measurements per day) using the format of up to three digits ("100" = 100% = complete).
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113. Origin of data (MM)
Code Origin Data measured on plotas described under location 1 in form PLM Data measured on nearby meteo stationother than 2 described under location in form PLM 3 Modelled data for gap filling 4 Modelled data 9 Missing value (data field must be blank)
114. Status of data (MM)
Code Status 1 Raw data / not calibrated 2 Validated data, not calibrated 3 Validated data, calibrated 9 Missing value (data field must be blank)
115. Description of instrument (MM) Short description of the instrument in Text format.
116. Codes for FAO Texture Classes (SO) The FAO Texture Triangle distinguished 12 classes of which the codes are given below (FAO, 1990): Texture Class Code Clay C Loam L Clay loam CL Silt Si Silt loam SiL Silty clay SiC Silty clay loam SiCL Sandy clay SC Sandy clay loam SCL Sandy loam SL Loamy sand LS
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Sand S
117. Code for depth level– Layers (SO)
CODE description OL Not saturated organic layer, litter horizon OF Not saturated organic layer, fermented horizon OFH Not saturated organic layer, fermented plus humus horizon (sampled together if OH horizon is not thicker than 1 cm) OH Not saturated organic layer, humus horizon Hf Saturated organic layer, poorly decomposed Hfs Saturated organic layer, fragmentized and partly oxidized Hs Saturated organic layer, well decomposed H05 Organic (peat) soil between 0 and 5 cm H51 Organic (peat) soil between 5 and 10 cm H01 Organic (peat) soil between 0 and 10 cm H12 Organic (peat) soil between 10 and 20 cm H24 Organic (peat) soil between 20 and 40 cm H48 Organic (peat) soil between 40 and 80 cm M05 Mineral soil between 0 and 5 cm M51 Mineral soil between 5 and 10 cm M01 Mineral soil between 0 and 10 cm M12 Mineral soil between 10 and 20 cm M24 Mineral soil between 20 and 40 cm M48 Mineral soil between 40 and 80 cm
118. Code for Parent Material (after Lambert et al., 2003(*)) (SO) The parent material code must be selected from the list provided below. It includes four levels: Major Class, Group, Type and Subtype. Depending on the level of detail available to describe the dominant and secondary parent materials, i.e. Major Class or Group or Type or Sub-type, the user will choose any one of the codes provided in the table. Whenever possible, it is recommended to identify as precisely as possible the exact type of parent material, using the full 4 digit code. For example, calcareous sandstone (1211) is preferable to sandstone (1210) or to psammite (1200). The later should be used either
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if the type of sandstone has can precisely been defined, or when more than one type of sandstone is present in the plot.
Major Sub- Group Type Class type level level level level 0000 No information 0000 No information 0000 No information 0000 No information 1000 consolidated-clastic- 1100 psephite or rudite 1110 conglomerate 1111 pudding stone sedimentary rocks 1120 breccia 1200 psammite or arenite 1210 sandstone 1211 calcareous sandstone 1212 ferruginous sandstone 1213 clayey sandstone 1214 quartzitic sandstone / orthoquartzite 1215 micaceous sandstone 1220 arkose 1230 graywacke 1231 feldspathic graywacke 1300 pelite, lutite or 1310 claystone / mudstone 1311 Kaolinite argilite 1312 Bentonite 1320 siltstone 1400 facies bound rock 1410 flysch 1411 sandy flisch 1412 clayey and silty flysch 1413 conglomeratic flysch 1420 molasse 2000 sedimentary rocks 2100 calcareous rocks 2110 limestone 2111 hard limestone (chemically precipitated, evaporated, or organogenic or biogenic in origin) 2112 soft limestone 2113 marly limestone 2114 chalky limestone 2115 detrital limestone 2116 carbonaceous limestone 2117 lacustrine or freshwater limestone 2118 Travertine/calcareous sinter 2119 Cavernous limestone 2120 dolomite 2121 Cavernous dolomite 2122 calcareous dolomite 2130 marlstone 2140 marl 2141 chalk marl 2142 gypsiferous marl 2150 chalk 2200 evaporites 2210 gypsum 2220 anhydrite 2230 halite 2300 siliceous rocks 2310 chert, hornstone, flint 2320 diatomite / radiolarite 3000 igneous rocks 3100 acid to intermediate 3110 granite plutonic rocks 3120 granodiorite 3130 diorite 3131 quartz diorite
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Major Sub- Group Type Class type level level level level 3132 gabbro diorite 3140 syenite 3200 basic plutonic rocks 3210 gabbro 3300 ultrabasic plutonic 3310 peridotite rocks 3320 pyroxenite 3400 acid to intermediate 3410 rhyolite 3411 Obsidian volcanic rocks 3412 quartz porphyrite 3420 dacite 3430 andesite 3431 porphyrite (interm,) 3440 phonolite 3441 tephritic phonolite 3450 trachyte 3500 basic to ultrabasic 3510 basalt volcanic rocks 3520 diabase 3530 pikrite 3600 dike rocks 3610 aplite 3620 pegmatite 3630 lamprophyre 3700 pyroclastic rocks 3710 tuff/tuffstone 3711 agglomeratic tuff (tephra) 3712 block tuff 3713 lapilli tuff 3720 tuffite 3721 sandy tuffite 3722 silty tuffite 3723 clayey tuffite 3730 volcanic scoria/ volcanic breccia 3740 volcanic ash 3750 ignimbrite 3760 pumice 4000 metamorphic rocks 4100 weakly metamorphic 4110 (meta-)shale / rocks argilite 4120 slate 4121 graphitic slate 4200 acid regional 4210 (meta-)quartzite 4211 quartzite schist metamorphic rocks 4220 phyllite 4230 micaschist 4240 gneiss 4250 granulite (sensu stricto) 4260 migmatite 4300 basic regional 4310 greenschist 4311 Prasinite metamorphic rocks 4312 Chlorite 4313 talc schist 4320 amphibolite 4330 eclogite 4400 ultrabasic regional 4410 serpentinite 4411 greenstone metamorphic rocks 4500 calcareous regional 4510 marble metamorphic rocks 4520 calcschist, skam 4600 rocks formed by 4610 contact slate 4611 nodular slate contact metamorphism
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Major Sub- Group Type Class type level level level level 4620 hornfels 4630 calsilicate rocks 4700 tectogenetic 4710 tectonic breccia metamorphism rocks or cataclasmic metamorphism 4720 cataclasite 4730 mylonite 5000 unconsolidated 5100 marine and 5110 pre-quaternary 5111 tertiary sand deposits (alluvium, estuarine sands sand weathering residuum and slope deposits) 5120 quaternary sand 5121 holocene coastal sand with shells 5122 delta sand 5200 marine and 5210 pre-quaternary clay 5211 tertiary clay estuarine clays and and silt silts 5212 tertiary silt 5220 quaternary clay and 5221 Holocene clay silt 5222 Holocene silt 5300 fluvial sands and 5310 river terrace sand 5311 river terrace sand gravels or gravel 5312 river terrace gravel 5320 floodplain sand or 5321 floodplain sand gravel 5322 floodplain gravel 5400 fluvial clays, silts 5410 river clay and silt 5411 terrace clay and silt and loams 5412 floodplain clay and silt 5420 river loam 5421 terrace loam
5430 overbank deposit 5431 floodplain clay and silt 5432 floodplain loam 5500 lake deposits 5510 lake sand and delta sand 5520 lake marl, bog lime 5530 lake silt 5600 residual and 5610 residual loam 5611 stony loam redeposited loams from silicate rocks 5612 clayey loam 5620 redeposited loam 5621 running-ground 5700 residual and 5710 residual clay 5711 clay with flints redeposited clays from calcareous rocks 5712 ferruginous residual clay 5713 calcareous clay 5714 non-calcareous clay 5715 marly clay 5720 redeposited clay 5721 stony clay 5800 slope deposits 5810 slope-wash alluvium
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Major Sub- Group Type Class type level level level level 5820 colluvial deposit 5830 talus scree 5831 Stratified slope deposits 6000 unconsolidated 6100 morainic deposits 6110 glacial till 6111 boulder clay glacial deposits / 6120 glacial debris glacial drift 6200 glaciofluvial 6210 outwash sand, deposits glacial sand 6220 outwash gravels glacial gravels 6300 glaciolacustrine 6310 varves deposits 7000 eolian deposits 7100 loess 7110 loamy loess 7120 sandy loess 7200 eolian sands 7210 dune sand 7220 cover sand 8000 organic materials 8100 peat (mires) 8110 rainwater fed moor 8111 folic peat peat (raised bog) 8112 fibric peat 8113 terric peat 8120 groundwater fed bog peat 8200 slime and ooze 8210 gyttja, sapropel deposits 8300 carbonaceaous 8310 lignite (brown coal) rocks (caustobiolite) 8320 hard coal 8330 anthracite 9000 anthropogenic 9100 redeposited natural 9110 sand and gravel fill deposits materials 9120 loamy fill 9200 dump deposits 9210 rubble/rubbish 9220 industrial ashes and slag 9230 industrial sludge 9240 industrial waste 9300 anthropogenic organic materials
(*) J.J. Lambert, J. Daroussin, M. Eimberck, C. Le Bas, M. Jamagne, D. King and L. Montanarella. 2003. Soil Geographical Database for Eurasia & The Mediterranean: Instructions Guide for Elaboration at scale 1:1,000,000, Version 4.0. European Soil Bureau Research Report N°8. EUR 20422 EN 64 pp. Office for Official Publications of the European Communities, Luxembourg.
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119. Code of the WRB Reference Soil Group (2006) (SO) Code Description Code Description AC Acrisol KS Kastanozem AB Albeluvisol LP Leptosol AL Alisol LX Lixisol AN Andosol LV Luvisol AT Anthrosol NT Nitisol AR Arenosol PH Phaeozem CL Calcisol PL Planosol CM Cambisol PT Plinthosol CH Chernozem PZ Podzol CR Cryosol RG Regosol DU Durisol SC Solonchak FR Ferralsol SN Solonetz FL Fluvisol ST Stagnosol GL Gleysol TC Technosol GY Gypsisol UM Umbrisol HS Histosol VR Vertisol
120. Code of the WRB Qualifier (1 till 6) (SO) Code Qualifier Code Qualifier Code Qualifier ap Abruptic ge Gelic pe Pellic ae Aceric gt Gelistagnic pt Petric ac Acric gr Geric pc Petrocalcic ao Acroxic gi Gibbsic pd Petroduric ab Albic gc Glacic py Petrogleyic ax Alcalic gl Gleyic pg Petrogypsic al Alic gb Glossialbic pp Petroplinthic aa Aluandic gs Glossic ps Petrosalic au Alumic gz Greyic px Pisoplinthic an Andic gm Grumic pi Placic aq Anthraquic gy Gypsic pa Plaggic am Anthric gp Gypsiric pl Plinthic ar Arenic ha Haplic po Posic ai Aric hm Hemic pf Profondic ad Aridic hi Histic pr Protic az Arzic ht Hortic pu Puffic br Brunic hu Humic ra Reductaquic ca Calcaric hg Hydragric rd Reductic cc Calcic hy Hydric rg Regic cm Cambic hf Hydrophobic rz Rendzic cb Carbic hb Hyperalbic * rh Rheic cn Carbonatic hl Hyperalic ro Rhodic cl Chloridic hc Hypercalcic ru Rubic cr Chromic hd Hyperdystric rp Ruptic ce Clayic he Hypereutric rs Rustic co Colluvic hp Hypergypsic sz Salic cy Cryic ho Hyperochric sa Sapric ct Cutanic hs Hypersalic sn Silandic
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Code Qualifier Code Qualifier Code Qualifier dn Densic hk Hyperskeletic sl Siltic dr Drainic wc Hypocalcic sk Skeletic du Duric wg Hypogypsic so Sodic dy Dystric wl Hypoluvic sc Solodic ek Ekranic ws Hyposalic sm Sombric nd Endoduric wn Hyposodic sd Spodic ny Endodystric ir Irragric sp Spolic ne Endoeutric ll Lamellic st Stagnic nf Endofluvic la Laxic sq Subaquic ng Endogleyic le Leptic su Sulphatic nl Endoleptic lg Lignic ty Takyric ns Endosalic lm Limnic te Technic et Entic lc Linic tf Tephric ed Epidystric li Lithic tr Terric ee Epieutric lx Lixic ba Taptantic el Epileptic lv Luvic bv Taptovitric ea Episalic mg Magnesic ti Thionic ec Escalic mf Manganiferric tp Thixotropic eu Eutric mz Mazic td Tidalic es Eutrosilic ml Melanic tx Toxic fl Ferralic ms Mesotrophic tn Transportic fr Ferric mo Mollic tu Turbic fi Fibric mi Mollicglossic um Umbric ft Floatic na Natric ug Umbriglossic fv Fluvic ni Nitic ub Urbic fo Folic nv Novic vm Vermic fp Fractipetric nt Nudilithic vr Vertic fa Fractiplinthic om Ombric vt Vetic fg Fragic oc Ornithic vi Vitric fu Fulvic os Ortsteinic vo Voronic ga Garbic oa Oxyaquic xa Xanthic ph Pachic ye Yermic
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The following codes are to be used for buried soils only. To use with the specifier Thapto:
Code Description Code Description AC Acrisolic KS Kastanozemic AB Albeluvisolic LP Leptosolic AL Alisolic LX Lixisolic AN Andosolic LV Luvisolic AT Anthrosolic NT Nitisolic AR Arenosolic PH Phaeozemic CL Calcisolic PL Planosolic CM Cambisolic PT Plinthosolic CH Chernozemic PZ Podzolic CR Cryosolic RG Regosolic DU Durisolic SC Solonchakic FR Ferralsolic SN Solonetzic FL Fluvisolic ST Stagnosolic GL Gleysolic TC Technosolic GY Gypsisolic UM Umbrisolic HS Histosolic VR Vertisolic
121. Code of the WRB Specifier (1 till 6) (SO) Note: if no specifier is needed, this field will have no value. Code Description Code Description Code Description d Bathi h Hyper r Para c Cumuli w Hypo t Proto n Endo o Ortho b Thapto p Epi
122. Code of WRB diagnostics (1 till 10) (SO) You may provide information of up till 10 diagnostic horizons, properties or materials. This field contains the code of the concerning horizon, property or material. a) Diagnostic horizons Code Description Code Description Code Description hab Albic horizon hgy Gypsic horizon hpx Pisoplinthic horizon haq Anthraquic horizon hhi Histic horizon hpa Plaggic horizon ham Anthric horizon hht Hortic horizon hpl Plinthic horizon hlv Argic horizon hhg Hydragric horizon hsz Salic horizon hcc Calcic horizon hir Irragric horizon hsm Sombric horizon hcm Cambic horizon hml Melanic horizon hsd Spodic horizon hcy Cryic horizon hmo Mollic horizon hty Takyric horizon hdu Duric horizon hna Natric horizon htr Terric horizon hfl Ferralic horizon hni Nitic horizon hti Thionic horizon hfr Ferric horizon hpc Petrocalcic horizon hum Umbric horizon
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hfo Folic horizon hpd Petroduric horizon hvr Vertic horizon hfg Fragic horizon hpg Petrogypsic horizon hvo Voronic horizon hfu Fulvic horizon hpp Petroplinthic horizon hye Yermic horizon b) Diagnostic properties Code Description Code Description pap Abrupt textural change pgl Gleyic colour pattern pab Albeluvic tonguing prp Lithological discontinuity pan Andic properties prd Reducing conditions pad Aridic properties pcc Secondary carbonates ple Continuous rock pst Stagnic colour pattern pfl Ferralic properties pvr Vertic properties pgr Geric properties pvi Vitric properties c) Diagnostic materials Code Description Code Description mte Artefacts mmn Mineral material mca Calcaric material mhi Organic material mco Colluvic material moc Ornithogenic material mfv Fluvic material mti Sulphidic material mgp Gypsiric material mek Technic hard rock mlm Limnic material mtf Tephric material
123. Depth of appearance of diagnostic (1 till 10) (SO) The depth of the upper limit of the diagnostic horizon/property/material in cm from upper limit of mineral soil is provided in this field. Note that on peat soils thicker than 40 cm, the 0 cm line is located at the upper limit of the peat layer.
124. WRB publication code (SO) Several editions of the WRB 2006 soil classification system exist. Here you should put a code referring the year of publication of the reference document used for the soil classification. The version used for Soil Classification has to be submitted with field "WRB publication code" in form .PRF using the code in the table below: code WRB publication (URL) 06en http://www.fao.org/ag/Agl/agll/wrb/doc/wrb2006final.pdf 07en http://www.fao.org/ag/agl/agll/wrb/doc/wrb2007_corr.pdf 07ge http://www.bgr.bund.de/cln_101/nn_336362/DE/Themen/Boden/Produkte/Schriften/ Downloads/ WRB__deutsche__Ausgabe,templateId=raw,property=publicationFile.pdf/ WRB_deutsche_Ausgabe.pdf
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code WRB publication (URL) XX99 other publication; respective link must be submitted in the field "observation text" and be announced to the FSCC at least 4 weeks before data submission for adoption or correction. document specification: code Reference document 06en IUSS Working Group WRB, 2006. World Reference Base for soil resources 2006. 2nd edition. World Soil Resource Reports N°. 103. FAO. Rome. 07en IUSS Working Group WRB. 2007. World Reference Base for Soil Resources 2006, first update 2007. World Soil Resources Reports No. 103. FAO, Rome. 07ge IUSS Working Group WRB. 2007. World Reference Base for Soil Resources 2006. Erstes Update 2007. Deutsche Ausgabe. – Übersetzt von Peter Schad. Herausgegeben von der Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover.
125. Repetition (SO) This is the order number of the composite when several composites are analysed for the same plot and depth layer. The first composite is numbered 1, the second composite is numbered 2, etc.
126. Layer limit superior/inferior (SO) The upper (lower) limit of the layer depth (in centimetres). The limit between the organic and mineral layer corresponds to 0 cm. For organic layers (OL, OF, OH, OFH, Hf, Hfs, Hs), the limits are negative values. For mineral layers (M05, M01, M51, M12, M24, M48) the limits are positive numbers.
127. Number of subsamples (SO) Number of subsamples in the composite.
128. Code horizon (horizon number) (SO, SW) Identification number of the horizon (horizon 1 = 1, horizon 2 = 2, etc.). The horizon is further indentified by the horizon designation (129) in the xx2009.PFH file.
129. Horizon designation (SO) The horizon designation is a combination of several symbols: (129).1 A number that gives information about discontinuities, i.e. the number of materials in which the soil has formed. This number is stored in the field HORIZON_DISCONTINUITY.
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(129).2 One or two capital letters that designate the type of master horizon (or transitional horizon). These letters are stored in the field HORIZON_MASTER. (129).3Lowercase letters that designate subordinate characteristics of the horizon. These letters are stored in the field HORIZON_SUBORDINATE. (129).4A number that designate vertical subdivisions. This number is stored in the field HORIZON_VERTICAL. (129).1 Horizon discontinuity This field contains a number to indicate a discontinuity in the horizon designation (mandatory if exists).
. When the soil has formed entirely in one kind of material, a zero (0) is used (the field is NOT empty). . When the soil has formed in several materials: o The upper part of the soil profile (corresponding to the first material) will be designated without number 1. o The part of the soil profile corresponding to the second material will be designated with the number 2. o The part of the soil profile corresponding to the third material will be designated with the number 3.
(129).2 Horizon master This field contains the code of the master horizon, following the descriptions below. Code Description H H horizon O O horizon OL OL horizon OF OF horizon OH OH horizon A A horizon E E horizon B B horizon C C horizon R R(ock) layer I I(ce) layer AB, BA, EB, Transitional horizon dominated by properties of one master horizon BE, BC, CR, (symbolised by the first letter) but having subordinate properties of another etc. master horizon (symbolized by the second letter). E/B, B/E, B/C Transitional horizon in which distinct parts have recognizable properties of etc. two kinds of master horizons.
(129).3 Horizon subordinate a Evidence of cryoturbation b Buried horizon
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c Concretions or nodules d Dense layer (physically root-restrictive, not used in combination with m) f Frozen soil (not used in combination with l) g Strong gleying h Accumulation of organic matter i Slickensides j Jarosite accumulation k Accumulation of pedogenetic carbonates m Strong cementation or induration (pedogenetic, massive) n Pedogenetic accumulation of exchangeable sodium o Residual accumulation of sesquioxides (pedogenetic) p Ploughing or other artificial disturbance q Accumulation of pedogenetic silica r Strong reduction s Illuvial accumulation of sesquioxides t Illuvial accumulation of clay u Urban and other man-made materials v Plinthite w Development of colour or structure in B (only used with B) x Fragipan y Pedogenetic accumulation of gypsum z Pedogenetic accumulation of salts more soluble than gypsum
(129).4 Horizon vertical A number is given to designate the vertical subdivision of a master horizon on the basis of structure, texture, colour, etc. The number 1 is used to designate the upper part of the master horizon. The number 2 the part of the master horizon situated below, etc. If there is no vertical subdivision,a0 (zero) shall be submitted.
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130. Horizon limit superior/inferior (SO) The upper/lower limit of the horizon depth (in centimetre). The limit between organic and mineral horizons corresponds to 0 cm. For organic horizons, the limits are negative values. For mineral horizons, the limits are positive values. Note that on peat soils thicker than 40 cm, the 0 cm line is located at the upper limit of the peat layer.
131. Horizon distinctness (SO) The distinctness of the lower horizon boundary refers to the thickness of the boundary zone in between adjacent horizons. The topography of the boundary indicates its shape.
Code Distinctness (cm) 1 Extremely abrupt 0.3 - 1 cm 2 Very abrupt 1 – 2 cm 3 Abrupt 0 - 2 cm 4 Clear 2 - 5 cm 5 Gradual 5 - 15 cm 6 Diffuse >15 cm
132. Horizon Topography (SO) The topography of the boundary indicates its shape.
Code Topography 1 Smooth Nearly plane surface 2 Wavy Pockets shallower than they are wide 3 Irregular Pockets deeper than they are wide 4 Broken Discontinuous 5 Complex
133. Structure (SO) Code Description 1 Platy 2 Prismatic 3 Columnar 4 Angular blocky 5 Subangular blocky 6 Granular 7 Crumbly 8 Massive
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9 Single grain 10 Wedge-shaped (e.g. slickensides)
134. Code coarse fragments (SO) Code Description 9 No stones or gravel 1 Very few (< 5% by volume) 2 Few (5 -15% by volume) 3 Frequent or many (15 – 40% by volume) 4 Very frequent, very many (40 – 80% by volume) 5 Dominant or skeletal (> 80% by volume)
135. Code porosity (SO) Code Description 1 very low (< 2 % by volume) 2 low (2 – 5 % by volume) 3 medium (5 – 15 % by volume) 4 high (15 – 40 % by volume) 5 very high (> 40 % by volume)
136. Mean highest and mean lowest ground water table (SO) Code Description 9 No groundwater table observed 1 Groundwater table between 0 – 50 cm 2 Groundwater table between 50 – 100 cm 3 Groundwater table between 100 – 150 cm 4 Groundwater table between 150 – 200 cm 5 Groundwater table between below 200 cm
137. Type of water table (SO) Code Description 9 No water table observed 1 Perched water table 2 Permanent water table
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138. Profile Depth measurement (SO) The effective rooting depth is the maximum depth till where roots have been observed during the profile description. The rock depth of the soil profile, is the depth where the continuous rock, if present, starts. In case the profile depth is limited by an obstacle different from continuous rock, (e.g. cemented layer, iron pan, permanent water table...) this depth should be reported in column 189-191 and the kind of obstacle should be noted in the field other observation. In case no rock or obstacle has been observed, the related fields should be left empty.
139. Root abundance (SO) The abundance of roots should be reported for four different size classes, using the codes ‘9, 1, 2, 3 or 4’ based on the frequency as number of roots/dm2.
Code Size class: Very fine Fine Medium Coarse Abundance: <0.5 mm 0.5-2 mm 2-5 mm >5 mm 9 None 0 0 0 0 1 Very few 1 - 20 1 - 20 1 - 2 1 - 2 2 Few 20 - 50 20 - 50 2 - 5 2 - 5 3 Common 50 - 200 50 - 200 5 - 20 5 - 20 4 Many >200 >200 >20 >20
140. First or last date of monitoring period (SS, DP,LF, MM, AQ) The first and final dates of each monitoring period shall be stated on the forms, using the same format as the date of observation, assessment and analysis (see item(3)). A monitoring period shall consist of one or more measuring periods. The measuring periods within one monitoring period should have the same length. The minimum length of a measuring period is one week, the maximum one month. When it is necessary to use different measuring periods during the year (e.g. weekly in summer and monthly in winter), two separate monitoring periods shall be identified and the results shall be reported separately on the forms.
141. Number of measuring periods/days (SS, DP, MM) The number of measuring periods or days (MM) in each monitoring period shall be indicated in the forms.
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142. Period (SS, DP) The measuring period number in which the sample has been collected shall be stated. Each year (on or around 1 January) a new set of measuring periods will be stated. When samples from several measuring periods are combined before analysis, the exact details of the mixing shall be stated in the Annex to the document with background information. The number of the first measuring period shall be used to indicate the period for analysis (e.g. when the samples from period 9, 10, 11, and 12 are combined into a single sample for the analysis, this sample will be given the period number 9).
143. Sampler(group)_ID (SS) The sampler(group)_ID defines a single sampler (Lysimeter) or a group of samplers (Lysimeters)with same attributes (Sampler type, depth and layer), from which a sample is collected in the field. The sampler_ID shall be numbered in a permanent and unique way (1-999). If the former attribute sampler number was already used in line with this definition of the sampler(group)_ID, the former numbers should be used now as sampler(group)_ID. If not please use sampler(group)_IDs which were not used already as Sampler numbers before to avoid confusions.
If a lysimeter needs replacement there are two options. If the sampler is replaced at the same spot, sampling depth, horizon and if the lysimeter is of the same type as before, the sampler(group)_ID should be kept to allow for time trend analysis. If the sampler is removed and another sampler is placed at another spot within the same plot, soil, depth horizon (for example in the case of big disturbance) or if the sampler even is of another type, it must be given a new ID that has not yet been used at this plot. Replacements of samplers can be reported using the field “other observations”. Only such a numbering guarantees consistency of plot information and data. This means that all samplers or a group of samplers at one plot must first be given first a (running) ID and then be described by assigning sampler type, sampled horizon, sampled depth and sample(group)_ID.
144. Sample_ID (SS) The sample_ID defines a sample which is foreseen for analysis. This might be a single ID for each sample of a single lysimeter (recommended) or one sample_ID for a pooled sample from serveral lysimeters of the same depth. The sample_ID must be unique and together with Country, Plotnumber, and Sampler(group)_ID clearly identifies data for the analysis.
Two examples for SSM:
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1. Sample from each Sampler/Sampler group (same Sampler(group)_ID) was analysed separately (each sampler creates an own sample_ID): !Sequence, plot, sampler_ID, sample_ID,date_start, date_end, period, sample_vol, pH, […] other_observations 0001 04 4321 001 01 010112 070112 1 00120 6.5 […] Sampler 1 0002 04 4321 001 02 070112 130112 2 00250 6.4 […] Sampler 1 0003 04 4321 001 03 130112 190112 3 00330 6.8 […] Sampler 1 […] 0053 04 4321 002 53 010112 070112 1 00460 6.2 […] Sampler 2 0054 04 4321 00254 070112 130112 2 00440 6.4 […] Sampler 2 0055 04 4321 00255 130112 190112 3 00370 6.1 […] Sampler 2
2. Pooled samples from different lysimeters with same attributes (sampled layer, depth and type) were analysed together due to e.g. too few volume in one period (several samplers contribute to one sample_ID): !Sequence, plot, sampler_ID, sample_ID,date_start, date_end, period, sample_vol, pH, […] other_observations 0001 04 4321 001 01 010112 070112 1 00250 6.5 […] Sampler 1 period 1 and 2 pooled 0002 04 4321 001 01 070112 130112 2 00250 6.5 […] Sampler 1period 1 and 2 pooled 0003 04 4321 001 02 130112 190112 3 00450 6.8 […] Sampler 1 […] 0053 04 4321 002 52 010112 070112 1 00460 6.2 […] Sampler 2 period 1 and 2 pooled 0054 04 4321 00252 070112 130112 2 00460 6.2 […] Sampler 2 period 1 and 2 pooled 0055 04 4321 00253 130112 190112 3 00370 6.1 […] Sampler 2 Summing up: sampler_id refers to the instrument, the sample_id refers to the gained sample which is analysed.
145. Type of layer (SS) The Type of layer should be specified using following codes: Code Describtion H Organic, water saturated, Hygromorphic M Mineral O Organic
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146. Sampler code (SS) The following codes shall be used for the samplers for soil solution:
Code Samplers for soil solution 1 Tension lysimeter 2 Zero tension lysimeter 3 Centrifugation 4 Saturation extraction 9 Other
147. Sampling depth (SS) The sampling depth in metres below the surface of the mineral soil in mineral soils, or below the top of all soil layers in organic soils (e.g. -0.40).
148. Number of Samplers (SS) Indicate the number of single lysimeters, which generating a sampler_ID. In case that every single lysimeter will produce a sample, which will be separately analysed, the number will be “1”. In case of pooling the samples (automatically) in the field the number of lysimeters should be recorded.
149. Volume per sample (SS) The sampling volume of each single sample should be reported. In case that single lysimeters are analysed this corresponds to the sample volume per lysimeter. If samples are pooled for analysis the mean, i.e. the volume of the pooled sample divided by the number of lysimeters should be reported.
150. Leaves type (FO) The definition of Leaves type:
Code Description 0 type 0: current = needle set 1 1 type 1: current+1 = needle set 2 2 type 2: older than current + 1 3 type 3: older than current foliage (combination of type 1 and type 2)
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151. SampleID Foliage (FO) The sample_ID defines samples of leaves which are analysed together. This might be a sample by 5 trees of the same species and leaves type or every tree will be analysed seperatly. In the first case all trees have the same sample ID for the same leaves type, in the second every tree (and leaves type) has an own sample ID. The Sample_ID should be unique in combination with Plot number.The sample ID allows for linkage between the forms FTR and FOM. In case that e.g. from a specific plot and a specific tree species and leaves type concentrations were measured for 5 single trees it is possible now to submit those 5 results with the sample IDs 1 to 5 and in addition (or alternatively) the pooled sample data may be submitted with an additional sample ID (e.g. “6”). The sample ID 1 to 5 would be linked to the respective tree numbers in form FTR (5 lines or records) and the pooled sample would be linked by sampleID 6 to the same 5 trees in additional 5 lines or records.
152. Tree number with initial F for Foliage, R for Ring and D for Disk sampling (FO, GR, PH, OZ) As in some samplings (foliar, increment, ozone injury) trees outside the normal plot (or sub plot) have to be used, special numbers have to be applied. The number of these trees will start with a letter (F=Foliage), R=Ring analysis by increment borings, D=Disc analysis) followed with a sequence number (e.g. F001). The numbers are to be reported. Ozone injury assessments are carried out on trees with foliar assessments and thus are numbered like these (e.g. F001). Only if additional trees are sampled specifically for ozone injury new codes are given (e.g. O001). The tree number must not change over time on individual trees. Assessment trees should be numbered in a unique way and permantly marked. The numbering should be valid for all surveys and should not differ from the numbering of the assessment given in the tree coordinate assessment.
153. Foliage Age class (FO) Specify the number of age classes, e.g. if only current leaves/needles insert “1”, if current plus last years leaves/needles insert “2” … etc. in case of unknown number of foliage classes insert “99”. A foliage age class is considered to be present if more than 50% of the needles / leaves are left in the annual shoot.
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154. Mass of 100 leaves or of 1000 needles (FO, LF) The mass is determined of 100 leaves or 1000 needles (oven-dry) in grams.
155. Trap number (LF) Trap number ist the unique number of the trap that has been assigned during installation. (Not: number of the traps per plot!)
156. Sample Code Litter Fractions (LF) code Fraction of Litterfall 10 Total litter biomass (all species) 11 Foliar litter (all species) 11.1 Foliar litter of main tree species 11.2 Foliar litter of other tree species 12 Non foliar litter total (all species) 13 Flowering total (including catkins) 13.1 Flowering main tree species 13.2 Other Flowering 14 Fruiting/seeds total (all species) 14.1 Fruiting/seeds + green cones (main species) 14.2 Fruit Capsules + empty cones (main species) 14.3 Rest of fruiting 14.4 Fruiting/seeds + green cones (other species) 14.5 Fruit Capsules + empty cones (other species) 15 Budshells Bud scales 16 Twigs/branches (<2cm) 17 Fines and Frass (<1mm) 19 Other biomass (lichen, moss etc.) In case that results are reported separately for compartments from different tree species (e.g. 11.1 and 11.2), make sure that the correct tree species (tree_species) is reported for each data set.
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157. Deposition sampler code (DP) The following codes shall be used for the samplers for deposition: Samplers for deposition Code Throughfall 1 Bulk deposition 2 Wet-only deposition 3 Stemflow 4 Fog 5 Frozen fog (rime) 6 Other 9
158. Sampler_ID Deposition (DP) The sampler(group)_ID defines a single sampler or a group of samplers from which a sample is collected in the field (1-999). This will be a group of samplers of the same sampler type, e.g. all throughfall samplers, which are pooled already in the field or only one sampler (e.g. wet only). The number of single samplers forming one Sampler_ID should be stated in the subsequent field
159. Sample_ID Deposition (DP) A Sample_ID is assigned to each sample that is analysed in the lab. The Sample_ID allows a clear coding if the same samples gained in the field are used in lab analysis with different temporal resolution. The Sample_ID should be unique in combination with Plot, Sampler_ID, Sampler code, Start date, and period for each sample used for analysis.
Examples for PLD and DEM/DEO for Sampler Code 1 = Throughfall: PLD: !Sequence, country, plot, sampler, sampler_ID, […], date_monitoring_1st, date_monitoring_last, periods, sampler_model, […] other_observations
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0001 04 4321 1 […] 001 010111 311211 12 1 […] standard sampling 0002 04 4321 1 […] 002 010111 311211 12 2 […] parallel with harmonized samplers 0003 04 4321 1 […] 003 010111 311211 04 1 […] quarterly aliquot for heavy metals DEM: !Sequence, plot, date_start, date_end, period, sampler, sampler_ID, sample_ID, V_sampling, quantity, pH, […], other_observations 0001 4321 010111 290111 1 1 001 0001 1 0031 5.6 […] standard sampling 0002 4321 290111 260211 2 1 001 0002 1 0042 5.4 […] standard sampling Too little volume for any analyses; sample pooled with following sample period: Same Sample_ID, quantity, and results for both periods: 0003 4321 260211 250311 3 1 001 0003 9 0032 5.5 […] too little volume, pooled 0004 4321 250311 220411 4 1 001 0003 1 0032 5.5 […] standard sampling […] Parallel equipment (harmonized sampler) installed on the same plot (Sampler_ID =2): 0013 4321 010111 290111 1 1 002 0012 1 0021 5.5 […] parallel equipment 0014 4321 290111 260211 2 1 002 0013 1 0032 5.3 […] parallel equipment […] DEO Quarterly aliquot for heavy metals (Sampler_ID = 3): !Sequence, plot, date_start, date_end, period, sampler, sampler_ID, sample_ID, V_sampling, quantity, Al, […] other_observations 0025 4321 010111 010411 1 1 003 0023 1 0035 1.06 […] aliquot only for hm 0026 4321 010411 010711 2 1 003 0024 1 0046 2.04 […] aliquot only for hm
160. Sampler Model – national / harmonised (DP)
Code Sampler Model 1 National 2 Harmonised
161. Sampler Height – deposition (DP) The height of the collecting surface above ground level in meters.
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162. Sampler Surface – deposition (DP) The area of the collecting surface for one sampler in m².
163. N of samplers (number of used samplers) (DP) Indicate the number of single samplers, which generating a sampler_ID. In case that every single sampler will produce a sample (and thus it has an own Sampler_ID), which will be separately analysed, the number will be “1”. In case of pooling the samples (auomatically) in the field the number of samplers should be recorded.
164. V_Sampling – missing/adjusted/estimated samples (DP) Code to be used to explain missing/adjusted/estimated samples:
Code Description 1 normal sampling 2 contamination (suspected or confirmed, whether analysis done or not) 3 sampler destroyed 4 sampling not performed 5 overflow, minimal precipitation derived from sampler volume given in 'quantity' is a minimum value 6 overflow, estimated precipiation (e.g. from meteorological station) given in 'quantity', estimation method specified in column 'Observations' or in the DAR-Q files 7 Normal sampling, but too little volume for any analyses (including zero precipitation) 8 normal sampling, but SOME analyses not done (e.g. due to too little volume) too little volume for analyses of SOME parameters 9 sample pooled in the lab for analysis with following sample period (e.g. due to too little volume) too little volume for any analyses; sample pooled with following sample period
165. Sample quantity (DP) In the DEM and DEO forms, the submission of with no analysis (e.g. no precipitation, no analytical results) should be distinguished from periods with missing data:
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For periods without precipitation, the start and end date has to be filled in and the column “sample quantity” has to be filled in with “0”, leaving all the other columns blank and in the column “Observations” the following remark has to be made “no precipitation”. For periods with missing data (e.g. lost samples), the start and end date has to be filled in and the precipitation quantity has to be indicated (if available) and in the column “Observations” the following remark has to be made “sample lost”. In case that no quantity value is availabe for a specific period the code “-9” should be used. Don’t use “0” here as this could be interpreted as “no precipitation” in this period.
166. Time Period of Hourly Measurement (AQ, MM) Time period of measurement. “00” to “23”, Hour in UTC, the period between 00:00 and 01:00 hours is referred to hour “00”, the period between 01:00 and 02:00 to hour “01”, etc.. Value “0“ is not valid for this data field.
167. Compound air quality (AQ) Code Description Unit
NH3 NH3 µg NH3/m³
NO2 NO2 µg NO2/m³
O3 O3 ppb
SO2 SO2 µg SO2/m³
168. Plot number in Air Quality files (AQ) See also (2) for format of this field. From 2009 onwards plot number is specified instead of active station ID. Each active sampler device is identified by plot number and sampler_ID (see (124)). These parameters are also used for link to the data submitted with form .AQA. General situation: In forms PAC, PPS, AQP and AQA passive sampler data (PPS and AQP) and hourly continuous analyzer data (PAC and AQA) measured at Intensive Monitoring Plots [IMP] are reported. Besides measurements taken at IMPs, passive samplers can also be co-located with continuous analyzers at Air Quality Stations [AQ_ST] (e.g. regional or EMEP Air Quality Stations, but not IMP) for quality control. In this case, for each of the exposure periods of the passive samplers (typically 2-weeks), both the measured value and its corresponding mean value measured with continuous analyzers for the same period have to be reported under form COL. If there are IMP with continuous analyzers and passive samplers measuring in parallel, then, both forms PAC, PPS, AQP
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and AQA, and COL as well have to be filled. In form COL, AQ_STs are identified with an S before the number (e.g. S004), while IMPs are identified only with plot numbers (e.g. 102).
169. Sampler ID (AQ) For continuous analyzers: If for a given pollutant and plot measurements are taken with more than one continuous analyzer, identify them with a different sampler_ID (e.g. with succesive numbers: 01, 02, 03, ...). For passive samplers: If for a given pollutant and plot, measurements are taken using several passive samplers (replicates), identify them with a different sampler_ID (e.g. with succesive numbers: 01, 02,03, ...)
170. Passive sampler manufacturer (AQ)
Passive sampler manufacturer Code CEAM with shelter 01 CEAM without shelter 02 Gradko with shelter 03 Gradko without shelter 04 Gradko combined SO2/NO2 with shelter 05 Gradko combined SO2/NO2 without shelter 06 IVL with shelter 07 IVL without shelter 08 Ogawa with shelter 09 Ogawa without shelter 10 Passam with shelter 11 Passam without shelter 12 Others with shelter (specify in "Observations") 13 Others without shelter (specify in "Observations") 14
171. Value Active/Passive Samplers (AQ)
For passive samplers, if measured values are below the limit ofquantification, use the code “-1” (in field “Value” of forms AQP and AQB or in the hourly concentration value fields of the respective componds in the AQA form) and report this limitunder the field “Other observations”. Missing data should be submitted as blank (NULL value).
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172. Continuos Analysers co-located with passive samplers (AQ) Y = Continuous analyzers and passive samplers co-located. If Yes, fill in also form COL.
173. Lowest evaluation in a circular area around ozone measurement (AQ) Draw a 2.5 km or 5.0 km, respectively, radius circle with the center being the point of ozone measurements (either with continuous analyzers of with passive samplers), and provide the lowest altitude in this area.
174. Profile pit ID (SW, SO) In general, samples from at least 3 pits on each depth with replicates are taken for the soil water determination. The PFHprofile pit ID is the Pit ID of the main pit on the plot for which the profile description was made and submitted with the PRF and the PFH file. In case that the profile description was made already during the BioSoil project or during a comparable assessment it is the same ID. The linkage between Soil Water data (SWC form) and Soil Profile description data (PRF and PFH) is built by a combination of the data fields
175. Soil Water pit ID (SW, MM) The Soil Water pit ID is used for numbering of the pit where samples for the soil water retention curve (SWRC) determination are taken, and for numbering of the pits where soil moisture measurements (SMM) are conducted. If both investigations are done in the same pit, the Soil Water pit ID should be the same in the forms SWC/SWA and PLM to apply the SWRC to the SMM at the same point. If this not the case, the ID should be different for SWRC and SMM measurements. In general, samples from at least 3 pits on each depth with replicates are taken for the soil water determination. The soil water ID of the actual Soil Water pit indicates where the soil water sample (SWRC or SMM) was taken. In case that this pit is the one on the plot for which the profile description was made (submitted with forms .PRF and .PFH) it is the same as the Profile pit ID (see (101)). In all other cases it is a new one.
176. Code for depth level – Layers Soil Water (SW) The linkage between the SWA and the SWC table is built by the key parameters of SWC. This means that each observation/line in SWA can be linked to exactly one observation/line in SWC by the combination of country, plot, date, SW_pit, depth_layer, and replicate. Each line in SWC is identified by such a specific combination of the respective values. Each line in SWA is identified by such a specific combination of the respective values and, in addition, a specific value for matric pressure.
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This data model implies that the depth layer code must be more or less unique. It is not possible to have to samples (one from 10 to 20 cm and one from 15 to 20cm) at the same pit with the identic depth layer code „M12“. Only 3 codes are fixed which are the mandatory depth layers M02, M24, and M48 (see table below). All others have to be defined by the submitting partner, making sure that each combination of country, plot, date, SW_pit, depth_layer, and replicate is unique in SWC and each observation in SWA can be linked to exactly one observation in SWC. In general, the depth layer code is built by an “O“ in case of organic layers or a “M” in case of mineral layers. Each succeed by two numbers. The first number is the decimeter of the upper limit and the second number it the decimeter of the lower limit. Example: A mineral layer from 19 cm to 22 cm would be “M12”, the layer below from 22 to 35cm would be “M23”. A layer below from 35 to 38cm would be “M33” and the next from 38 to 51cm would be “M35”. The depth layer codes M02, M24, and M48 are exclusively defined for the upper and lower limits in the table below:
Example Upper Lower Layers description for Code limit limit Organic layer (Forest floor > 5 cm thick Oxx mandatory) -10 0 Sample ring depth lower limit is top of mineral O10 layer (depth is “0”) and upper limit is 10 cm above (value “-10”) Mxx Mineral layer M01 0 10 Mineral soil between 0 and 10 cm (optional) M12 10 20 Mineral soil between 10 and 20 cm (optional) M02 0 20 Mineral soil between 0 and 20 cm (mandatory) M24 20 40 Mineral soil between 20 and 40 cm (mandatory) M48 40 80 Mineral soil between 40 and 80 cm (mandatory) M81 80 100 Mineral soil below 80cm to 1m (optional) M82 80 200 Mineral soil below 80cm to 2m (optional) The code is specified in order to allow for a fast evaluation of mandatory soil water data classified as foreseen in the above table. The sample ring depths allow a more detailed description. Examples for SWC and SWA tables and the linkage of data between them: !SWC !Sequence, country, plot, date, profile_pit, horizon, SW_pit, depth_layer, ring_depth_upper, ring_depth_lower, replicate, bulk_density, date_analysis, other_observations 1 22 901 010709 901A 1 901A M02 0 20 1 810 010809 testdata 2 22901 020709 901B 1 901B M02 0 20 1 820 020809 testdata 3 22 901 050709 901B 2 901B M24 20 40 1 850 050809 testdata
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…. The data line below (sequence number 142) is linked by the values for country, plot, date, SW_pit, depth_layer, and replicate to the second observation in SWC: !SWA !Sequence, country, plot, date, SW_pit, depth_layer, replicate, water_content, matric_pressure, date_analysis, other_observations …. 142 22 901 020709 901BM021 0.15 -1 020809 testdata ….
177. Other observations (all) Any supplementary comments.
178. Foliage & Litterfall & Ground Vegetation & Deposition & Soil – pretreatment methods (QA-Forms) Code Pretreatment methods FO LF GB DP SO 0 No information X X X X X 1 No pretreatment X X X X X 2 Extractions X X X X
2.11 Single BaCl2 extraction X
2.12 Triple BaCl2 extraction X 2.2 Extraction KCl 2.3 Extraction aqua regia X X X X
2.4 Total extraction with HF/HClO4 X
2.5 Total extraction with LiBO2 X 2.6 Extraction with Acid ammonium oxalate X
2.7 Extraction H2O X X X X
2.8 Extraction HNO3 X X X
2.9 Extraction CaCl2 X 3 Wet ashings at room pressure (open system) X X X X
3.1 Wet ashing HNO3 X X X
3.11 Wet ashing HNO3 /H2SO4 X X X
3.12 Wet ashing aqua regia (HCl/HNO3) X X X X 3.2 Wet ashing HNO3/HF X X X
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Code Pretreatment methods FO LF GB DP SO 3.21 Wet ashing HClO4/H2O2 X X X 3.22 Wet ashing HClO4/H2SO4 X X X 3.3 Wet ashing HNO3/HClO4 X X X 3.31 Wet ashing H2SO4/H2O2 X X X 3.32 Wet ashing H2SO4/K2CrO7 X X X 3.4 Wet ashing HNO3/HClO4/HF X X X 3.5 Wet ashing HNO3/H2O2 X X X 3.51 Kjeldahl H2SO4/ Se-catalyst X X X 3.52 Kjeldahl H2SO4/Cu-catalyst X X X 3.53 Kjeldahl H2SO4/Ti-Cu-catalyst X X X X 3.54 Kjeldahl H2SO4/Hg-catalyst X X X 3.6 Wet ashing HNO3/HClO4 /H2SO4 X X X 3.7 Wet ashing HNO3/HClO4/CaCl2 X X X 3.8 Wet ashing HNO3/HClO4/H2O2 X X X 3.9 Wet ashing HNO3,/HClO4/HCl X X X 4 Pressure digestions (closed system) X X X X 4.1 Pressure digestion HNO3 X X X X 4.2 Pressure digestion HNO3/HF X X X X 4.3 Pressure digestion HNO3/HClO4 X X X X 4.4 Pressure digestion HNO3/HClO4/HF X X X X 4.5 Pressure digestion HNO3/H2O2 X X X X 5 Microwave pressure digestions (closed X X X X system) 5.1 Microwave digestion HNO3 X X X X 5.2 Microwave digestion HNO3/HF X X X X 5.3 Microwave digestion HNO3/HClO4 X X X X 5.4 Microwave digestion HNO3/HClO4/HF X X X X 5.5 Microwave digestion HNO3/H2O2 X X X X 5.6 Microwave digestion HNO3/H2O2/HF X X X X 5.7 Microwave digestion HNO3/H2O2/HCl X X X X 5.8 Microwave aqua regia X X X X 6 Dry ashings X X X X 6.1 Dry ashing dissolution with HNO3 X X X X 6.2 Dry ashing dissolution with HNO3/MgNO3 X X X X 6.3 Dry ashing dissolution with HNO3/HF X X X X 6.4 Dry ashing dissolution with HNO3/HCl X X X X
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Code Pretreatment methods FO LF GB DP SO 6.5 Dry ashing dissolution with HCl X X X X 6.6 Dry ashing dissolution with HCl/HF X X X X 6.7 Dry ashing dissolution with H2SO4 X X X X 7 Oxygen ashings X X X 7.1 Oxygen ashing Schöniger X X X 7.2 Oxygen ashing Wickbold X X X 7.3 Oxygen ashing calorimetric bomb X X X 8.2 Hydrolysis with X K2S2O8 + H3BO3 + NaOH 8.3 Persulfate digestion X (K2S2O8 + H2SO4) 8.4 Persulfate digestion X (K2S2O8 + NaOH) 8.7 Other deposition pretreatment X (please specify per email) 9 X-ray-pretreatments and other pretreatments X X X 9.1 Material pressed (pellet) X X X 9.2 Material melted and formed (tablet) X X X 9.5 Melting (NaOH) X X X
179. Foliage, Soil Solution, Soil, Litterfall, Ground Vegetation Biomass, Deposition – determination methods (QA forms) Code Determination method FO/LF/ SO SS/ DP GB 0 No information x 1 No detection x x x 10 Elemental-analyzers x x x 11 Kjeldahl-apparatus x x x 11.1 Kjeldahl-apparatus (Tecator) x x x 11.2 Kjeldahl-apparatus (Gerhardt) x x x 11.3 Kjeldahl-apparatus (Büchi) x x x 12 N-Analyzer x x x 12.1 N-Analyzer (Heraeus/Elementar ) x x x 12.2 N-Analyzer (Vario) x x x 12.3 N-Analyzer (Leco) x x x
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Code Determination method FO/LF/ SO SS/ DP GB 13 C-Analyzer x x x 13.1 C-Analyzer (Leco) x x x 13.2 TOC Analyzer x x x 13.3 C-Analyzer (Heraeus/Elementar) x x x 14 S-Analyzer x x x 14.1 S-Analyzer (Leco)x x x x 15 C/N-Analyzer x x x 15.1 C/N-Analyzer (Carlo-Erba=CE Instruments) x x x 15.2 C/N-Analyzer (Leco) x x x 15.3 C/N-Analyzer (Heraeus/Elementar) x x x 15.4 C/N-Analyzer (Vario) x x x 15.5 C/N-Analyzer (Hekatech) x x x 16 C/S-Analyzer x x x 16.1 C/S-Analyzer (Leco) x x x 17 C/N/S-Analyzer x x x 17.1 C/N/S-Analyzer (Leco) x x x 17.2 C/N/S-Analyzer (Heraeus/Elementar) x x x 17.3 C/N/S-Analyzer (Thermo Electron) x x x 17.4 C/N/S-Analyzer (Carlo-Erba=CE Instruments) x x x 18 C/N/H-Analyzer x x x 18.1 C/N/H-Analyzer (Leco) x x x 18.2 C/H/N-Analyzer (Heraeus/Elementar) x x x 19 C/H/N/S-Analyzer x x x 20 Mono-Atom-Spectrometry-Techniques x x x 21 AAS-flame technique x x x 21.1 AAS-flame technique (C2H2/Air) x x x 21.2 AAS-flame technique (C2H2/N2O) x x x 22 AAS-flameless (electrothermal technique) x x x 24 AAS-hydride technique x x x 25 AAS-cold vapor technique x x x 25.1 AAS-LECO/ALTEC Mercury Analyzer x x x 26 AFS-hydride-technique x x x 28 AES-Flame photometer x x x 30 Multi-Atom-Spectrometry-techniques x x x 31 ICP-AES without Ultrasonic nebulisation x x x
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Code Determination method FO/LF/ SO SS/ DP GB 32 ICP-AES with Ultrasonic nebulisation x x x 35 ICP-MS x x x 40 Physical techniques x x x 41 X-ray-energy dispersive x x x 42 X-ray-wavelength dispersive x x x 45 Neutron activation analysis (NAA) x x x 47 Gamma-spectroscopy x x x 48 Laser diffraction x x x 50 UV-VIS-spectrophotometry-techniques x x x 51 Colorimetric N-Determination x x x 51.1 Indophenol-blue-method x x x 51.2 Flow Injection (FIAS)-NH3-Membrane- x x x diffusion 566 nm 51.3 Continuous flow method, Indophenol blue x x x 52 Colorimetric S-Determination x x x 52.1 Nephelometry x x x 52.2 Turbidimetry x x x 53 Colorimetric P-Determination x x x 53.1 Molybdene-blue-method x x x 53.2 Vanadium-Mo-blue-method x x x 53.3 Continuous flow method, Molybdene-blue x x x 54 Colorimetric B-Determination x x x 54.1 Azomethin – H x x x 54.2 Carmine x x x 55 Colorimetric C-Determination x x 60 Ion-chromatographic techniques x x x 61.1 Anion-Chromatography w. chemical x x x suppression 61.2 Anion-Chromatography w. electr. suppression x x x 62.1 Kation-Chromatography w. chemical x x x suppression 62.2 Kation-Chromatography w. electr. suppression x x x 70 Electrochemical methods x x x 71 Conductimetry x x x 71.1 Conductometric titration x x x 72 Potentiometry x x x
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Code Determination method FO/LF/ SO SS/ DP GB 72.1 pH x x 72.2 other ion selective electrodes x x x 73 Potentiometric titrations x x x 74 Stripping potentiometry x x x 75 Voltammetry x x x 76 Polarography x x x 77 Amperometry x x x 78 Electrophoresis x x x 79 Redox potential x x x 80 Classical analytical techniques x x x 81 Gravimetry x x x 81.1 Pipette x x 81.2 Hydrometer x x 82 Titration x x x 82.1 NH4-back titration x x x 82.2 Thiocyanate-titration x x x 82.3 FeNH4SO4-Titration x x x 82.4 Barimetric titration x x x 82.5 AgNO3-Titration x x x 83 Calcimeter (Scheibler unit) x x 84 Carbon determinations x x 84.1 Loss on ignition x x 84.2 Walkley-Black x x 84.3 Tjurin method x x 90 other detections x x x 91 Calculation x x
180. QA parameter (QA forms) a) Laboratories For each parameter the laboratory has to evaluate the quantification limit (in unit of parameter) and to use a control chart over the year. Then the mean of the control chart and the relative standard deviation in [%] (= absolute value of coefficient of variation in % = (stdev / mean)*100) has to be evaluated and to be submitted.
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b) Ringtests For each parameter the results from the last ring test have to be submitted. The participation (yes=1, no =0 (or 9)), the ring test number and the lab ID are the same for all parameters. In the exceptional case that a lab ID shall be submitted even though there is no ringtest participation ring_test_participation =9. The percentage of results within tolerable limit (see your individual ring test report) for each parameter has to be reported; if the percentage is lower than 50 % the laboratory has to requalify. In this case success of the requalification (yes=1, no =0) has to be reported. The percentage of results within tolerable limit after requalification can be submitted in the last column of the form.
181. Foliage and Ground Vegetation biomass – parameter (QA forms) code Compound Units N Nitrogen mg/g S Sulphur mg/g P Phosphorus mg/g Ca Calcium mg/g Mg Magnesium mg/g K Potassium mg/g C Carbon g/100g Zn Zinc μg/g Mn Manganese μg/g Fe Iron μg/g Cu Copper μg/g Pb Lead μg/g Cd Cadmium ng/g B Boron μg/g
182. Soil Solution – parameter (QA forms) code parameter unit pH pH value Cond conductivity µS/cm K Potassium mg/L Ca Calcium mg/L Mg Magnesium mg/L N_NO3 Nitrate-N mg/L S_SO4 Suphate-S mg/L Alkalin Alkalinity µmolc/L
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code parameter unit Al Aluminium mg/L DOC Dissolved Organic Carbon mg/L Na Sodium mg/L Al_labile labile Aluminium mg/L Fe Iron mg/L Mn Manganese mg/L P total Phosphorus mg/L N_NH4 Ammonium- N mg/L Cl Chloride mg/L Zn Zinc µg/L Cu Copper µg/L Cr Chromate µg/L Ni Nickel µg/L Pb Lead µg/L Cd Cadmium µg/L Si Silicium mg/L
P_PO4 Phosphate mg/L N_total Total Nitrogen mg/L
183. Deposition – parameter (QA forms) code parameter unit pH pH value Cond Conductivity µS/cm K Potassium mg/L Ca Calcium mg/L Mg Magnesium mg/L Na Sodium mg/L N_NH4 Ammonium- N mg/L Cl Chloride mg/L N_NO3 Nitrate- N mg/L S_SO4 Sulphate- S mg/L Alkalin Alkalinity μeq/L N_total total Nitrogen mg/L DOC Dissolved Organic Carbon mg/L Al Aluminium μg/L Mn Manganese μg/L Fe Iron μg/L
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code parameter unit P_PO4 Phosphate- P mg/L Cu Copper μg/L Zn Zinc μg/L Hg Mercury μg/L Pb Lead μg/L Co Cobalt μg/L Mo Molybdenum μg/L Ni Nickel μg/L Cd Cadmium μg/L S_total total Sulphur mg/L C_total total Carbon mg/L
184. Litterfall – parameter (QA forms) code parameter unit N Nitrogen mg/g S Sulphur mg/g P Phophor mg/g Ca Calcium mg/g Mg Magnesium mg/g K Potassium mg/g C Carbon g/100g Zn Zinc μg/g Mn Manganese μg/g Fe Iron μg/g Cu Copper μg/g Pb Lead μg/g Cd Cadmium ng/g B Boron μg/g
185. Soil – parameter (QA forms) code parameter Pclay percentage clay Psilt percentage silt Psand percentage sand pH_CaCl2 pH in CaCl2 pH_H2O pH in H2O
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code parameter org_C Organic Carbon Total_N total Nitrogen CaCO3 Carbonate Acid_exch Exchangeable Acidity Al_exch Exchangeable Aluminium Ca_exch Exchangeable Calcium Fe_exch Exchangeable Iron K_exch Exchangeable Potassium Mg_exch Exchangeable Magnesium Mn_exch Exchangeable Manganese Na_exch Exchangeable Sodium Free_H+ Free Acidity Al_extr Extractable Aluminium Ca_extr Extractable Calcium Cd_extr Extractable Cadmium Cr_extr Extractable Chromium Cu_extr Extractable Copper Fe_extr Extractable Iron Hg_extr Extractable Mercury K_extr Extractable Potassium Mg_extr Extractable Magnesium Mn_extr Extractable Manganese Na_extr Extractable Sodium Ni_extr Extractable Nickel P_extr Exctractable Phosphorus Pb_extr Extractable Lead S_extr Extractable Sulphur Zn_extr Extractable Zinc Al_tot total Aluminium Ca_tot total Calcium Fe_tot total Iron K_tot total Potassium Mg_tot total Magnesium Mn_tot total Manganese Na_tot total Sodium Al_react Reactive Aluminium Fe_react Reactive Iron
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186. SoilRemoval Compounds (QA forms) CODE Description 1 No removal 2 Removal of organic carbon 2.1 Hydrogen peroxide 2.2 Pre-ignition at 850°C 3 Removal of soluble salts and gypsum 3.1 Washing with water 4 Removal of carbonates 4.1 Hydrochloric acid 4.2 Hydrochloric acid/Calcium chloride 5 Removal of OC and carbonates 6 Removal of OC, carbonates, soluble salts and gypsum
187. Soil – sieving / milling (QA forms) CODE soil – sieving/milling 1 Sieving and/or crushing 1.1 mesh size < 2 mm 1.2 other mesh size 2 Milling 2.1 To 150 micrometer 2.2 As fine as possible 9 Other method
188. start_date, end_date (QA forms) In order to enable the coding of the change of the analyzing laboratory during a year start_date and end_date were integrated into the QA forms. The start_date is the first (analysing) date from which the laboratory analysed the data from the respective plot, sampler and parameter. The end_date is the last day of the analyses of the respective plot sampler and parameter combination. Only in case, that a laboratory has been changed during one monitoring year, it would be nessecary to use an additional data row with the respective time period in which the new laboratory has been analysing the data. The format of the field is the same as described in explanatory item 3 (DDMMYY).
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189. LAI Survey_ID (LA) For each type of measurement or sampling on a given plot use an unique ID, which must not change over time. If e.g. hemispherical photos are taken on a plot in Aug 2012 and in Aug 2013, both surveys may receive the same ID (001), if SAI is measured in December 2012, this will receive LAI survey ID 002.
190. Method for LAI determination (LA) According to Field Protocol on LAI measurement: Code Description 10 Direct determination (Litterfall) 21 Canopy analyzer – LICOR 2000 22 Canopy analyzer – TRAC 23 Canopy analyzer – other (to be described in detail) 31 digital camera – WinScanopy 32 digital camera – HemiView 33 digital camera – GLA 34 digital camera – other (to be described in detail in the “observations” field) 35 digital camera - Hemisfer 41 SunScan Ceptometer 51 Air borne LIDAR 61 Biomass harvest 99 Other (to be described in detail in the “observations” field)
191. Date of maximum foliation and PAI (LA) The expected date of maximum foliation shall be given as an independent estimation. In most cases this is based on literature or on expert estimation. If only a certain month can be specified, insert the 15th day of the month (e.g. 150712 indicates that maximum foliation is expected in July).
PAIeff always needs to be submitted. If LAImax can not be calculated (e.g. due to missing clumping correction, or missing SAI), only submit PAI.
192. LAImax (LA) LAImax is the final measurement outcome and needs to be entered here irrespective of what method has been used.
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193. Point_ID (LA) Each measurement point is given a unique number with four digits, e.g. 0016. A separate entry is given for the average of all measurement points, the measurement point number is 9999 in this case. The measurement point number is similar to the device ID (27) in form LAC and is a key field to link these forms.
194. LAI – results (LA)
Code Parameter 500 Gap fraction [%]* Woody to total plant area ratio α (if 600 applied)** 700 Stem area index SAI (if measured)** 800 Within-shoot clumping coefficient γ ** 900 Clumping coefficient [-]* * Hemispherical measurement values Gap fraction, PAIeff, andare given without correction in the pure form that is calculated from the image evaluation software used. If is derived from other sources (e.g. TRAC), the date of observation and measurement type are given in the observations field. ** Indirect optical measurement values Only in case of the use of a hemispherical method, within shoot clumping and the contributions of woody material need to be considered. Then, either SAI (derived from the respective PAIeff winter values in form .LAP or taken from form .LBH) or α needs to be given. Species-specific values for α and γ may be taken from the literature or own measurements, the source shall be indicated in the observations field. The within-shoot clumping coefficient γ may be assumed to be 1 for most broadleaf trees.
195. Date of related SAI measurement (winter, if applicable) (LA) The date of related SAI measurement does not need to be submitted if the parameter to be specified is SAI. For the other cases the date of related SAI measurement needs to be submitted. This does not necessarily be in the same year,
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instead it may be up to five years old as SAI is not expected to change as dynamically as LAI.
196. Sky conditions (LA) Sky conditions during the measurement are classified according to the following scheme: Code Description 10 Standard overcast (homogenous sky) 11 cloudy (more than 50% of the sky covered by clouds) 12 clear (less than 50% of the sky covered by clouds)
197. Sun position (LA) Sun position can only be given as one of two values: Code Description 20 Sun above the horizon 21 Sun below the horizon
198. Exposure time (LA) Exposure time is given relatively to the exposure settings proposed by the camera spotmeter measurement for the sky observed through a gap or in open area. E.g. +1.5a means that exposure is +1.5 step higher than automatic ABOVE CANOPY exposure settings.
199. Matric pressure – Volumetric water content (SW) Determinations of volumetric water content made in the FutMon project should be done according to following pre-set matric pressures: pF kPa volumetric soil water content (m3.m-3) 0.0 0 (= Total Porosity) Mandatory 1.0 -1 Mandatory 1.7 -5 Mandatory 2.0 -10 Optional 2.5 -33 Mandatory
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pF kPa volumetric soil water content (m3.m-3) 3.0 -100 Optional 3.4 -250 Optional 4.2 -1500 Mandatory
200. Functional Group – Ground Vegetation Biomass Analyses (GB) code Functional group 1 Bryophytes 2 Lichens 3 Ferns 4 Grasses 5 Herbs 6 Foliage of deciduous shrubs 6b Stems of deciduous shrubs 7 Foliage of evergreen shrubs 7b Stems of evergreen shrubs 8 Rest
201. Frame area [m²] (GB) Ground vegetation is sampled using a frame of known area. In case that modeled results are submitted (e.g. based on Phytocalc) insert “-9”.
202. No of frames (GB) In case that modeled results are submitted (e.g. based on Phytocalc) insert “-9”.
203. Sampled area [m²] (GB) Total sampled area as sum of all frames, or in case of modeled results (e.g. Phytocalc) area for which results apply.
204. Cumulative LAI and SLAsampled_area (LA)
The collected leaf area is summed up over the whole litterfall year (LAIcum) or over the time after maximum foliation has been reached (LAImax), for each species separately. Adapted to the seasons of the northern hemisphere, a whole year is
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often defined from March to February, but this may need to be adapted regionally according to the vegetation period. It is important to report LAI not only until end of December but until the end of the complete litterfall year. Specific leaf area and the average leaf area of leaves sampled for its determination are as well given per species.
6 Literature UNECE/FAO 2010: Annex to Enquiry State of Forests and Sustainable Forest Management in Europe 2011. New European Forest Types. Complementary documentation. http://timber.unece.org/fileadmin/DAM/publications/european- forest-type.pdf(accessed 18 March 2010)
Page 178/178 193 Food and Agriculture Organization of the United Nations (2006) IUSS Working Group WRB. World reference base for soil resources 2006. World Soil Resources Reports 103. ftp://ftp.fao.org/docrep/fao/009/a0510e/a0510e00.pdf reproduced with permission
194 iii
Contents
Foreword vii Acknowledgements viii List of acronyms and abbreviations ix 1. Background to the world reference base for soil resources 1 History 1 From its beginnings to the first edition in 1998 1 From the first edition in 1998 to the second edition in 2006 2 Basic principles 3 Architecture 4 Key to the Reference Soil Groups 4 The qualifier level 6 Principles and use of the qualifiers in the WRB 6 The geographical dimension of WRB qualifiers – match to mapping scale 7 The object classified in the WRB 7 Rules for classification 8 Step one 8 Step two 8 Step three 8 Example of WRB soil classification 9
2. Diagnostic horizons, properties and materials 11 Diagnostic horizons 11 Albic horizon 11 Anthraquic horizon 12 Anthric horizon 12 Argic horizon 13 Calcic horizon 15 Cambic horizon 16 Cryic horizon 17 Duric horizon 17 Ferralic horizon 18 Ferric horizon 19 Folic horizon 20 Fragic horizon 20 Fulvic horizon 21 Gypsic horizon 22 Histic horizon 23 Hortic horizon 23 Hydragric horizon 24 Irragric horizon 24 Melanic horizon 25 Mollic horizon 25 Natric horizon 26 Nitic horizon 28 195 iv
Petrocalcic horizon 29 Petroduric horizon 30 Petrogypsic horizon 30 Petroplinthic horizon 31 Pisoplinthic horizon 32 Plaggic horizon 32 Plinthic horizon 33 Salic horizon 34 Sombric horizon 35 Spodic horizon 35 Takyric horizon 36 Terric horizon 37 Thionic horizon 38 Umbric horizon 38 Vertic horizon 39 Voronic horizon 40 Yermic horizon 41 Diagnostic properties 41 Abrupt textural change 41 Albeluvic tonguing 41 Andic properties 42 Aridic properties 43 Continuous rock 44 Ferralic properties 44 Geric properties 45 Gleyic colour pattern 45 Lithological discontinuity 46 Reducing conditions 46 Secondary carbonates 47 Stagnic colour pattern 47 Vertic properties 47 Vitric properties 47 Diagnostic materials 48 Artefacts 48 Calcaric material 48 Colluvic material 49 Fluvic material 49 Gypsiric material 49 Limnic material 49 Mineral material 50 Organic material 50 Ornithogenic material 50 Sulphidic material 51 Technic hard rock 51 Tephric material 51
3. Key to the reference soil groups of the WRB with lists of prefix and suffix qualifiers 53
4. Description, distribution, use and management of reference soil groups 67 Acrisols 67 Albeluvisols 68
196 v
Alisols 69 Andosols 70 Anthrosols 71 Arenosols 72 Calcisols 74 Cambisols 75 Chernozems 76 Cryosols 76 Durisols 77 Ferralsols 78 Fluvisols 79 Gleysols 80 Gypsisols 81 Histosols 82 Kastanozems 83 Leptosols 84 Lixisols 85 Luvisols 86 Nitisols 87 Phaeozems 88 Planosols 88 Plinthosols 89 Podzols 91 Regosols 92 Solonchaks 92 Solonetz 94 Stagnosols 95 Technosols 95 Umbrisols 96 Vertisols 97
5. Definitions of formative elements for second-level units of the WRB 101
References 121
Annexes 1. Summary of analytical procedures for soil characterization 123 2. Recommended codes for the reference soil groups, qualifiers and specifiers 127
197 vi
List of tables
1. Rationalized Key to the WRB Reference Soil Groups 5 2. Prefix and suffix qualifiers in the WRB – case of Cryosols 6
198 vii
Foreword
The first official version of the World Reference Base for Soil Resources (WRB) was released at the 16th World Congress of Soil Science at Montpellier in 1998. At the same event, it was also endorsed and adopted as the system for soil correlation and international communication of the International Union of Soil Sciences (IUSS). After eight years of intensive worldwide testing and data collection, the current state- of-the-art of the WRB is presented. This publication reflects the valuable work of the authors of the earlier drafts and the first version of the WRB, as well as the experiences and contributions of many soil scientists who participated in the work of the IUSS Working Group on the WRB. Globalization and global environmental issues necessitate harmonization and correlation of technical languages, such as the one used in soil science. It is hoped that this publication will contribute to the understanding of soil science in the public debate and in the scientific community. The publication has been made possible by the sustained efforts of a large group of expert authors, and the cooperation and logistic support of the IUSS, the International Soil Reference and Information Centre (ISRIC) and the Food and Agriculture Organization of the United Nations (FAO).
Erika Michéli (Chair), Peter Schad (Vice-Chair) and Otto Spaargaren (Secretary) IUSS Working Group WRB
David Dent ISRIC – World Soil Information
Freddy Nachtergaele FAO Land and Water Development Division
199 viii
Acknowledgements
The text of this publication is based on numerous valuable contributions from hundreds of soil scientists worldwide. They participated in field tours, workshops and conferences; they sent comments, and they tested the World Reference Base for Soil Resources (WRB) approach. This publication would not have been possible without the support of a number of international institutes and organizations, notably the Food and Agriculture Organization of the United Nations (FAO), the National Resources Conservation Service of the United States of America, the European Soils Bureau hosted by the Joint Research Centre of the European Commission, the West and Central African Union of Soil Scientists Association, and the International Soil Reference and Information Centre (ISRIC) – World Soil Information, to name only the major ones. Last but not least, the Working Group World Reference Base of the International Union of Soil Sciences (IUSS) was supported by other IUSS working groups, in particular the Soils in Urban, Industrial, Traffic and Mining Areas Working Group and the Cryosol Working Group of the IUSS/International Permafrost Association. National soil institutes in many countries assisted in WRB field tours, and organized conferences and WRB summer schools (listed in Chapter 1). This edition has been edited by Erika Michéli (Szent István University, Hungary), Peter Schad (Technische Universität München, Germany) and Otto Spaargaren (ISRIC – World Soil Information, Netherlands). Particular mention should go to Richard Arnold (United States of America), Hans-Peter Blume (Germany) and Rudi Dudal (Belgium). They were involved from the inception of the International Reference Base, more than 25 years ago, and have provided invaluable institutional memory for the objectives and approach. The Working Group wishes to express its gratitude to FAO for its support and for making possible the printing and distribution of this publication.
200 ix
List of acronyms and abbreviations
Al Aluminium Ca Calcium
CaCO3 Calcium carbonate CEC Cation exchange capacity COLE Coefficient of linear extensibility EC Electrical conductivity
ECe Electrical conductivity of saturation extract ECEC Effective CEC ESP Exchangeable sodium percentage FAO Food and Agriculture Organization of the United Nations Fe Iron HCl Hydrochloric acid IRB International Reference Base for Soil Classification ISRIC International Soil Reference and Information Centre ISSS International Society of Soil Science IUSS International Union of Soil Sciences K Potassium KOH Potassium hydroxide Mg Magnesium Mn Manganese N Nitrogen Na Sodium NaOH Sodium hydroxide ODOE Optical density of the oxalate extract P Phosphorus RSG Reference Soil Group S Sulphur SAR Sodium adsorption ratio
SiO2 Silica SUITMA Soils in Urban, Industrial, Traffic and Mining Areas (special working group) Ti T itanium TRB Total reserve of bases UNEP United Nations Environment Programme UNESCO United Nations Educational, Scientific, and Cultural Organization USDA United States Department of Agriculture WRB W orld Reference Base for Soil Resources Zn Zinc
201 202 1
Chapter 1 Background to the world reference base for soil resources
HISTORY
From its beginnings to the first edition in 1998 In the early 1980s, countries became increasingly interdependent for their supplies of food and agricultural products. Problems of land degradation, disparity of production potentials and of population-carrying capacities became international concerns that required harmonized soil information. Against this background, the Food and Agriculture Organization of the United Nations (FAO) felt that a framework should be created through which existing soil classification systems could be correlated and harmonized. Concurrently, it would serve as an international means of communication and for exchange of experience. The elaboration of such a framework required a more active involvement of the entire soils community. At the initiative of FAO, the United Nations Educational, Scientific, and Cultural Organization (UNESCO), the United Nations Environment Programme (UNEP), and the International Society of Soil Science (ISSS), a group of soil scientists representing a broad range of soil institutions met in Sofia, Bulgaria, in 1980 and 1981 to enhance international involvement in a follow-up to the Soil Map of the World (FAO–UNESCO, 1971–1981). The meeting was hosted by the Poushkarov Institute of Soil Science and Yield Programming. The meeting decided to launch a programme to develop an International Reference Base for Soil Classification (IRB) with the aim to reach agreement on the major soil groupings to be recognized at a global scale, as well as on the criteria to define and separate them. It was expected that such an agreement would facilitate the exchange of information and experience, provide a common scientific language, strengthen the applications of soil science, and enhance communication with other disciplines. The group met in 1981 for a second time at Sofia and laid down the general principles of a joint programme towards the development of an IRB. In 1982, the 12th Congress of the ISSS, in New Delhi, India, endorsed and adopted this programme. The work was conducted by a newly created IRB working group, chaired by E. Schlichting with R. Dudal serving as secretary. At the 13th Congress of the ISSS, in Hamburg, Germany, in 1986, the IRB programme was entrusted to Commission V, with A. Ruellan as chair and R. Dudal as secretary. These charges were continued through the 14th Congress of the ISSS, in Kyoto, Japan, in 1990. In 1992, the IRB was renamed the World Reference Base for Soil Resources (WRB). Hence, a WRB working group was established at the 15th Congress of the ISSS, in Acapulco, Mexico, in 1994, with J. Deckers, F. Nachtergaele and O. Spaargaren as chair, vice-chair and secretary, respectively, through the 16th Congress of the ISSS, in Montpellier, France, in 1998. At the 17th World Congress of Soil Science, in Bangkok, Thailand, in 2002, the leadership for the WRB programme was entrusted to E. Michéli, P. Schad and O. Spaargaren as chair, vice-chair and secretary, respectively. At a meeting of the IRB Working Group in Montpellier in 1992, it was decided that the revised FAO–UNESCO legend would form the basis for the further development of the IRB and that efforts were to be merged. It would be the task of the IRB to apply its general principles to the further refinement of the FAO–UNESCO units and to provide them with the necessary depth and validation. 203 2 World reference base for soil resources 2006
Progress in the preparation of the WRB was reported to the 15th Congress of the ISSS at Acapulco in 1994 (FAO, 1994). Numerous contributions were received from soil scientists; the WRB was discussed and tested in meetings and excursions at Leuven, Belgium (1995), Kiel, Germany (1995), Moscow, Russian Federation (1996), South Africa (1996), Argentina (1997) and Vienna, Austria (1997). The first official text of the WRB was presented at the 16th World Congress of Soil Science in Montpellier in 1998 in three volumes: 1. World Reference Base for Soil Resources. An introduction. 2. World Reference Base for Soil Resources. Atlas. 3. World Reference Base for Soil Resources. The WRB text was then adopted by the ISSS Council as the officially recommended terminology to name and classify soils. By general agreement, it was then decided that the text would remain unchanged for at least eight years, but that it would be tested extensively during this period and a revision proposed at the 18th World Congress of Soil Science in 2006.
From the first edition in 1998 to the second edition in 2006 In the period 1998–2006, the WRB became the official reference soil nomenclature and soil classification for the European Commission and was adopted by the West and Central African Soil Science Association as the preferred tool to harmonize and exchange soil information in the region. The main text was translated in 13 languages (Chinese, French, German, Hungarian, Italian, Japanese, Latvian, Lithuanian, Polish, Rumanian, Russian, Spanish and Vietnamese) and adopted as a higher level of the national soil classification system in a number of countries (e.g. Italy, Mexico, Norway, Poland and Viet Nam). The text was further illustrated by lecture notes and a CD-ROM on the major soils of the world (FAO, 2001a and 2001b) and a World Soil Resources Map at a scale 1:25 000 000 by the Joint Research Centre, FAO and the International Soil Reference and Information Centre (ISRIC) in 2002. A Web site was established (http://www.fao.org/landandwater/agll/wrb/default.stm) and a newsletter was distributed to hundreds of soil scientists. Specific attention was paid to land-use and soil management issues for tropical and dryland soils using WRB information (FAO, 2003 and 2005). Numerous articles appeared in peer-reviewed soil science journals and books, suggesting improvements to the system. Two conferences were held together with field trips: in 2001 in Velence (Hungary, organized by the Szent István University in Gödöllö); and in 2004 in Petrozavodsk (Russian Federation, organized by the Institute of Biology, Karelian Research Centre). At the same time, a number of field excursions were organized to test and refine the WRB approach in the field: Burkina Faso and Côte d’Ivoire (1998); Viet Nam and China (1998); Italy (1999); Georgia (2000); Ghana and Burkina Faso (2001); Hungary (2001); South Africa and Namibia (2003); Poland (2004); Italy (2004); Russian Federation (2004); Mexico (2005); Kenya and the United Republic of Tanzania (2005); and Ghana (2005). Summer schools, coordinated by E. Michéli (Hungary), were organized under the auspices of the EU Joint Research Centre in Ispra, Italy (2003 and 2004), and in Gödöllö, Hungary (2005), to teach the system to soil science students and practitioners. In the same period, the European Commission issued the Soil Atlas of Europe based on the WRB (European Soil Bureau Network/European Commission, 2005). A major effort was undertaken to harmonize nomenclature with the soil taxonomy of the United States Department of Agriculture (USDA) and other major national soil classification systems. Some national classifications took up elements of the WRB, e.g. the Chinese soil taxonomy (CRGCST, 2001), the Czech soil classification (N me ek et al., 2001), the Lithuanian soil classification (Buivydaité et al., 2001), and the Russian soil classification system (Shishov et al., 2001). A WRB e-mail forum was organized in 2005 to enable finalization of suggestions for each Soil Reference Soil Group. Independently, 204 Chapter 1 – Background to the world reference base for soil resources 3
special working groups of the International Union of Soil Sciences (IUSS) (formerly the ISSS), such as the ones on Cryosols and on Soils in Urban, Industrial, Traffic and Mining Areas (SUITMA) proposed changes to the system, some of which have been adopted in the present text. The second edition of the WRB has undergone a major revision. Technosols and Stagnosols have been introduced, leading to 32 Reference Soil Groups (RSGs) instead of 30. The Technosols are soils with a certain amount of artefacts, a constructed geomembrane or technic hard rock. The Stagnosols unify the former Epistagnic subunits of many other RSGs. Some re-arrangement has taken place in the order of the key, with Anthrosols, Solonetz, Nitisols and Arenosols moving upwards. The definitions of many diagnostic soil horizons, soil properties, and materials have been adjusted. The qualifiers are now subdivided into prefix and suffix ones. Prefix qualifiers comprise those that are typically associated with the RSG (in order of their importance) and the intergrades to other RSGs (in order of the key). All other qualifiers are listed as suffix qualifiers.
BASIC PRINCIPLES
The general principles on which the WRB is based were laid down during the early Sofia meetings in 1980 and 1981, and further elaborated upon by the working groups entrusted with its development. These general principles can be summarized as follows: ÿ The classification of soils is based on soil properties defined in terms of diagnostic horizons, properties and materials, which to the greatest extent possible should be measurable and observable in the field. ÿ The selection of diagnostic characteristics takes into account their relationship with soil forming processes. It is recognized that an understanding of soil-forming processes contributes to a better characterization of soils but that they should not, as such, be used as differentiating criteria. ÿ To the extent possible at a high level of generalization, diagnostic features are selected that are of significance for soil management. ÿ Climate parameters are not applied in the classification of soils. It is fully realized that they should be used for interpretation purposes, in dynamic combination with soil properties, but they should not form part of soil definitions. ÿ The WRB is a comprehensive classification system that enables people to accommodate their national classification system. It comprises two tiers of categorical detail: • the Reference Base, limited to the first level only and having 32 RSGs; • the WRB Classification System, consisting of combinations of a set of prefix and suffix qualifiers that are uniquely defined and added to the name of the RSG, allowing very precise characterization and classification of individual soil profiles. ÿ Many RSGs in the WRB are representative of major soil regions so as to provide a comprehensive overview of the world’s soil cover. ÿ The Reference Base is not meant to substitute for national soil classification systems but rather to serve as a common denominator for communication at an international level. This implies that lower-level categories, possibly a third category of the WRB, could accommodate local diversity at country level. Concurrently, the lower levels emphasize soil features that are important for land use and management. ÿ The Revised Legend of the FAO/UNESCO Soil Map of the World (FAO, 1988) has been used as a basis for the development of the WRB in order to take advantage of international soil correlation that has already been conducted through this project and elsewhere. 205 4 World reference base for soil resources 2006
ÿ The first edition of the WRB, published in 1998, comprised 30 RSGs; the second edition, published in 2006, has 32 RSGs. ÿ Definitions and descriptions of soil units reflect variations in soil characteristics both vertically and laterally so as to account for spatial linkages within the landscape. ÿ The term Reference Base is connotative of the common denominator function that the WRB assumes. Its units have sufficient width to stimulate harmonization and correlation of existing national systems. ÿ In addition to serving as a link between existing classification systems, the WRB also serves as a consistent communication tool for compiling global soil databases and for the inventory and monitoring of the world’s soil resources. ÿ The nomenclature used to distinguish soil groups retains terms that have been used traditionally or that can be introduced easily in current language. They are defined precisely in order to avoid the confusion that occurs where names are used with different connotations. Although the basic framework of the FAO Legend (with its two categorical levels and guidelines for developing classes at a third level) was adopted, it has been decided to merge the lower levels. Each RSG of the WRB is provided with a listing of possible prefix and suffix qualifiers in a priority sequence, from which the user can construct the second-level units. The broad principles that govern the WRB class differentiation are: ÿ At the higher categorical level, classes are differentiated mainly according to the primary pedogenetic process that has produced the characteristic soil features, except where special soil parent materials are of overriding importance. ÿ At the second level, soil units are differentiated according to any secondary soil- forming process that has affected the primary soil features significantly. In certain cases, soil characteristics that have a significant effect on use may be taken into account. It is recognized that a number of RSGs may occur under different climate conditions. However, it was decided not to introduce separations on account of climate characteristics so that the classification of soils is not subordinated to the availability of climate data.
ARCHITECTURE
Currently, the WRB comprises two tiers of categorical detail: 1. Tier 1: The RSGs, comprising 32 RSGs; 2. Tier 2: The combination of RSGs with qualifiers, detailing the properties of the RSGs by adding a set of uniquely defined qualifiers.
Key to the Reference Soil Groups The Key to the RSGs in the WRB stems from the Legend of the Soil Map of the World. The history behind the Key to the Major Soil Units of the Legend of the Soil Map of the World reveals that it is mainly based on functionality; the Key was conceived to derive the correct classification as efficiently as possible. The sequence of the Major Soil Units was such that the central concept of the major soils would come out almost automatically by specifying briefly a limited number of diagnostic horizons, properties or materials. Table 1 provides an overview and logic for the sequence of the RSGs in the WRB Key. The RSGs are allocated to sets on the basis of dominant identifiers, i.e. the soil- forming factors or processes that most clearly condition the soil formation. The sequencing of the groups is done according to the following principles: 1. First, organic soils key out to separate them from mineral soils (Histosols). 206 Chapter 1 – Background to the world reference base for soil resources 5
2. The second major distinction in the WRB is to recognize human activity as a soil-forming factor, hence the position of the Anthrosols and Technosols after the Histosols; it also appears logical to key out the newly-introduced Technosols close to the beginning of the Key, for the following reasons: ÿ one can almost immediately key out soils that should not be touched (toxic soils that should be handled by experts); ÿ a homogeneous group of soils in strange materials is obtained; ÿ politicians and decision-makers who consult the Key will immediately encounter these problematic soils. 3. Next are the soils with a severe limitation to rooting (Cryosols and Leptosols). 4. Then comes a group of RSGs that are or have been strongly influenced by water: Vertisols, Fluvisols, Solonetz, Solonchaks, and Gleysols. 5. The following set of soil groups are the RSGs in which iron (Fe) and/or aluminium (Al) chemistry plays a major role in their formation: Andosols, Podzols, Plinthosols, Nitisols and Ferralsols.
TABLE 1 Rationalized Key to the WRB Reference Soil Groups 1. Soils with thick organic layers: Histosols 2. Soils with strong human influence Soils with long and intensive agricultural use: Anthrosols Soils containing many artefacts: Technosols 3. Soils with limited rooting due to shallow permafrost or stoniness Ice-affected soils: Cryosols Shallow or extremely gravelly soils: Leptosols 4. Soils influenced by water Alternating wet-dry conditions, rich in swelling clays: Vertisols Floodplains, tidal marshes: Fluvisols Alkaline soils: Solonetz Salt enrichment upon evaporation: Solonchaks Groundwater affected soils: Gleysols 5. Soils set by Fe/Al chemistry Allophanes or Al-humus complexes: Andosols Cheluviation and chilluviation: Podzols Accumulation of Fe under hydromorphic conditions: Plinthosols Low-activity clay, P fixation, strongly structured: Nitisols Dominance of kaolinite and sesquioxides: Ferralsols 6. Soils with stagnating water Abrupt textural discontinuity: Planosols Structural or moderate textural discontinuity: Stagnosols 7. Accumulation of organic matter, high base status Typically mollic: Chernozems Transition to drier climate: Kastanozems Transition to more humid climate: Phaeozems 8. Accumulation of less soluble salts or non-saline substances Gypsum: Gypsisols Silica: Durisols Calcium carbonate: Calcisols 9. Soils with a clay-enriched subsoil Albeluvic tonguing: Albeluvisols Low base status, high-activity clay: Alisols Low base status, low-activity clay: Acrisols High base status, high-activity clay: Luvisols High base status, low-activity clay: Lixisols 10. Relatively young soils or soils with little or no profile development With an acidic dark topsoil: Umbrisols Sandy soils: Arenosols Moderately developed soils: Cambisols Soils with no significant profile development: Regosols 207 6 World reference base for soil resources 2006
6. Next comes a set of soils with perched water: Planosols and Stagnosols. 7. The next grouping comprises soils that occur predominantly in steppe regions and have humus-rich topsoils and a high base saturation: Chernozems, Kastanozems and Phaeozems. 8. The next set comprises soils from the drier regions with accumulation of gypsum (Gypsisols), silica (Durisols) or calcium carbonate (Calcisols). 9. Then comes a set of soils with a clay-rich subsoil: Albeluvisols, Alisols, Acrisols, Luvisols and Lixisols. 10. Finally, relatively young soils or soils with very little or no profile development, or very homogenous sands, are grouped together: Umbrisols, Arenosols, Cambisols and Regosols.
The qualifier level In the WRB, a distinction is made between typically associated qualifiers, intergrades and other qualifiers. Typically associated qualifiers are referred to in the Key to the particular RSGs, e.g. Hydragric or Plaggic for the Anthrosols. Intergrade qualifiers are those that reflect important diagnostic criteria of another RSG. The WRB Key will, in that case, dictate the choice of the RSG and the intergrade qualifier will provide the bridge to the other RSG. Other qualifiers are those not typically associated with an RSG and that do not link to other RSGs, e.g. Geric or Posic for Ferralsols. This group reflects characteristics such as colour, base status, and other chemical and physical properties provided that they are not used as a typically associated qualifier in that particular group.
Principles and use of the qualifiers in the WRB A two-tier system is used for the qualifier level, comprising: ÿ Prefix qualifiers: typically associated qualifiers and intergrade qualifiers; the sequence of the intergrade qualifiers follows that of the RSGs in the WRB Key, with the exception of Arenosols; this intergrade is ranked with the textural suffix qualifiers (see below). Haplic closes the prefix qualifier list indicating that neither typically associated nor intergrade qualifiers apply. ÿ Suffix qualifiers: other qualifiers, TABLE 2 sequenced as follows: (1) qualifiers related Prefix and suffix qualifiers in the WRB – case of to diagnostic horizons, properties or Cryosols materials; (2) qualifiers related to chemical Prefix qualifiers Suffix qualifiers Glacic Gypsiric characteristics; (3) qualifiers related to Turbic Calcaric physical characteristics; (4) qualifiers Folic Ornithic* related to mineralogical characteristics; (5) Histic Dystric qualifiers related to surface characteristics; Technic Eutric (6) qualifiers related to textural Hyperskeletic Reductaquic* characteristics, including coarse fragments; Leptic Oxyaquic Natric Thixotropic (7) qualifiers related to colour; and (8) Salic Aridic remaining qualifiers. Vitric Skeletic ÿ Table 2 provides an example of the listing Spodic Arenic of prefix and suffix qualifiers. Mollic Siltic Prefix qualifier names are always put Calcic Clayic* before the RSG; suffix qualifier names are Umbric Drainic* always placed between brackets following Cambic Novic* Haplic the RSG name. Combinations of qualifiers * = newly introduced qualifiers that indicate a similar status or duplicate each Examples: other are not permitted, such as combinations 1. Histic Turbic Cryosol (Reductaquic, Dystric). 2. Haplic Cryosol (Aridic, Skeletic). of Thionic and Dystric, Calcaric and Eutric, or Rhodic and Chromic. 208 Chapter 1 – Background to the world reference base for soil resources 7
Specifiers such as Epi-, Endo-, Hyper-, Hypo-, Thapto-, Bathy-, Para-, Proto-, Cumuli- and Ortho- are used to indicate a certain expression of the qualifier. When classifying a soil profile, all applying qualifiers of the listing must be recorded. For mapping purposes, the scale will determine the number of qualifiers used. In that case, prefix qualifiers have priority over the suffix qualifiers. The qualifier listing for each RSG accommodates most cases. Where not listed qualifiers are needed, the cases should be documented and reported to the WRB Working Group.
The geographical dimension of WRB qualifiers – match to mapping scale The WRB was not designed originally for mapping soils but its roots are in the Legend of the Soil Map of the World. Before the WRB came into existence, the FAO Legend was used for soil mapping at various scales, and rather successfully (e.g. soil mapping in Bangladesh, Botswana, Ethiopia, the European Union, Kenya, and the United Republic of Tanzania). Whether desirable or not, people are using the WRB as a tool for soil mapping (e.g. 1:1 000 000 scale Soil Map of Europe; 1:250 000 Soil Map of the Central Highlands of Viet Nam). A basic principle in soil mapping is that the soil surveyor designs the legend of the map so as to best suit the purpose of the survey. If the WRB is designed to support small-scale mapping of the global soil landscapes, it would be advantageous to have a structure that lends itself to support such overview maps. Hence, the discussion on the qualifier listings should not be held in isolation of the overview maps of the soils of the world or the continents in the WRB. Therefore, it is suggested that the WRB qualifiers be linked to small-scale soil maps as follows: ÿ prefix qualifiers for mapping between 1/5*106 and 1/106 scale; ÿ suffix qualifiers for mapping between 1/106 and 1/250*103 scale. For larger mapping scales, it is suggested that, in addition, national or local soil classification systems be used. They are designed to accommodate local soil variability, which can never be accounted for in a world reference base.
THE OBJECT CLASSIFIED IN THE WRB
Like many common words, the word soil has several meanings. In its traditional meaning, soil is the natural medium for the growth of plants, whether or not it has discernible soil horizons (Soil Survey Staff, 1999). In the 1998 WRB, soil was defined as: “… a continuous natural body which has three spatial and one temporal dimension. The three main features governing soil are: ÿ It is formed by mineral and organic constituents and includes solid, liquid and gaseous phases. ÿ The constituents are organized in structures, specific for the pedological medium. These structures form the morphological aspect of the soil cover, equivalent to the anatomy of a living being. They result from the history of the soil cover and from its actual dynamics and properties. Study of the structures of the soil cover facilitates perception of the physical, chemical and biological properties; it permits understanding the past and present of the soil, and predicting its future. ÿ The soil is in constant evolution, thus giving the soil its fourth dimension, time.” Although there are good arguments to limit soil survey and mapping to identifiable stable soil areas with a certain thickness, the WRB has taken the more comprehensive approach to name any object forming part of the epiderm of the earth (Nachtergaele, 2005). This approach has a number of advantages, notably that it allows tackling environmental problems in a systematic and holistic way and avoids sterile discussions 209 8 World reference base for soil resources 2006
on a universally agreed definition of soil and its required thickness and stability. Therefore, the object classified in the WRB is: any material within 2 m from the Earth s surface that is in contact with the atmosphere, with the exclusion of living organisms, areas with continuous ice not covered by other material, and water bodies deeper than 2 m1. The definition includes continuous rock, paved urban soils, soils of industrial areas, cave soils as well as subaqueous soils. Soils under continuous rock, except those that occur in caves, are generally not considered for classification. In special cases, the WRB may be used to classify soils under rock, e.g. for palaeopedological reconstruction of the environment. The lateral dimension of the object classified should be large enough to represent the nature of any horizon and variability that may be present. The minimum horizontal area may range from 1 to 10 m2 depending on the variability of the soil cover.
RULES FOR CLASSIFICATION
Classification consists of three steps.
Step one The expression, thickness and depth of layers are checked against the requirements of WRB diagnostic horizons, properties and materials, which are defined in terms of morphology and/or analytical criteria (Chapter 2). Where a layer fulfils the criteria of more than one diagnostic horizon, property or material, they are regarded as overlapping or coinciding.
Step two The described combination of diagnostic horizons, properties and materials is compared with the WRB Key (Chapter 3) in order to find the RSG, which is the first level of WRB classification. The user should go through the Key systematically, starting at the beginning and excluding one by one all RSGs for which the specified requirements are not met. The soil belongs to the first RSG for which it meets all specified requirements.
Step three For the second level of WRB classification, qualifiers are used. The qualifiers are listed in the Key with each RSG as prefix and suffix qualifiers. Prefix qualifiers comprise those that are typically associated to the RSG and the intergrades to other RSGs. All other qualifiers are listed as suffix qualifiers. For classification at the second level, all applying qualifiers have to be added to the name of the RSG. Redundant qualifiers (the characteristics of which are included in a previously set qualifier) are not added. Specifiers can be used to indicate the degree of expression of qualifiers. Buried layers can be indicated by the Thapto- specifier, which can be used with any qualifier, listed in Chapter 5. Where a soil is buried under new material, the following rules apply: 1. The overlying new material and the buried soil are classified as one soil if both together qualify as Histosol, Technosol, Cryosol, Leptosol, Vertisol, Fluvisol, Gleysol, Andosol, Planosol, Stagnosol or Arenosol. 2. Otherwise, the new material is classified at the first level if the new material is 50 cm or more thick or if the new material, if it stood alone, fits the requirements of a RSG other than a Regosol. 3. In all other cases, the buried soil is classified at the first level.
1 In tidal areas, the depth of 2 m is to be applied at low tide. 210 Chapter 1 – Background to the world reference base for soil resources 9
4. If the overlying soil is classified at the first level, the buried soil is recognized with the Thapto- specifier and -ic added to the RSG name of the buried soil. The whole is placed in brackets after the name of the overlying soil, e.g. Technic Umbrisol (Greyic) (Thapto-Podzolic). If the buried soil is classified at the first level, the overlying material is indicated with the Novic qualifier. It is recommended that the Guidelines for Soil Description (FAO, 2006) be used to describe the soil and its features. It is useful to list the occurrence and depth of diagnostic horizons, properties and materials identified. The field classification provides a preliminary assessment using all observable or easily measurable properties and features of the soil and associated terrain. The final classification is made when analytical data are available. It is recommended that Procedures for Soil Analysis (Van Reeuwijk, 2006) is followed in determining chemical and physical characteristics. A summary of these is included in Annex 1.
Example of WRB soil classification A soil has a ferralic horizon; texture in the upper part of the ferralic horizon changes from sandy loam to sandy clay within 15 cm. The pH is between 5.5 and 6, indicating moderate to high base saturation. The B horizon is dark red; below 50 cm, mottling occurs. The field classification of this soil is: Lixic Ferralsol (Ferric, Rhodic). If subsequent laboratory analysis reveals that the cation exchange capacity (CEC) of the -1 ferralic horizon is less than 4 cmolc kg clay, the soil finally classifies as Lixic Vetic Ferralsol (Ferric, Rhodic).
211 212 11
Chapter 2 Diagnostic horizons, properties and materials
Diagnostic horizons and properties are characterized by a combination of attributes that reflect widespread, common results of the processes of soil formation (Bridges, 1997) or indicate specific conditions of soil formation. Their features can be observed or measured, either in the field or in the laboratory, and require a minimum or maximum expression to qualify as diagnostic. In addition, diagnostic horizons require a certain thickness, thus forming a recognizable layer in the soil. Diagnostic materials are materials that influence pedogenetic processes significantly.
DIAGNOSTIC HORIZONS
Albic horizon General description The albic horizon (from Latin albus, white) is a light-coloured subsurface horizon from which clay and free iron oxides have been removed, or in which the oxides have been segregated to the extent that the colour of the horizon is determined by the colour of the sand and silt particles rather than by coatings on these particles. It generally has a weakly expressed soil structure or lacks structural development altogether. The upper and lower boundaries are normally abrupt or clear. The morphology of the boundaries is variable and sometimes associated with albeluvic tonguing. Albic horizons usually have coarser textures than the overlying or underlying horizons. However, with respect to an underlying spodic horizon, this difference may only be slight. Many albic horizons are associated with wetness and contain evidence of reducing conditions.
Diagnostic criteria An albic horizon has: 1. a Munsell colour (dry) with either: a. a value of 7 or 8 and a chroma of 3 or less; or b. a value of 5 or 6 and a chroma of 2 or less; and 2. a Munsell colour (moist) with either: a. a value of 6, 7 or 8 and a chroma of 4 or less; or b. a value of 5 and a chroma of 3 or less; or c. a value of 4 and a chroma of 2 or less1. A chroma of 3 is permitted if the parent materials have a hue of 5 YR or redder, and the chroma is due to the colour of uncoated silt or sand grains; and 3. a thickness of 1 cm or more.
Field identification Identification in the field depends on soil colours. In addition, a ×10 hand-lens may be used to ascertain that sand and silt grains are free of coatings.
1 Colour requirements have been changed slightly with respect to those defined by FAO–UNESCO–ISRIC (FAO, 1988) and Soil Survey Staff (1999) in order to accommodate albic horizons with a considerable shift in chroma when wetted. Such albic horizons occur frequently in, for example, southern Africa.
213 12 World reference base for soil resources 2006
Additional characteristics The presence of coatings around sand and silt grains can be determined using an optical microscope for analysing thin sections. Uncoated grains usually show a very thin rim at their surface. Coatings may be of an organic nature, consist of iron oxides, or both, and are dark coloured under translucent light. Iron coatings become reddish in colour under reflected light, while organic coatings remain brownish-black.
Relationships with some other diagnostic horizons Albic horizons are normally overlain by humus-enriched surface layers but may be at the surface as a result of erosion or artificial removal of the surface layer. They can be considered an extreme type of eluvial horizon, and usually occur in association with illuvial horizons such as an argic, natric or spodic horizon, which they overlie. In sandy materials, albic horizons can reach considerable thickness, up to several metres, especially in humid tropical regions, and associated diagnostic horizons may be hard to establish.
Anthraquic horizon General description An anthraquic horizon (from Greek anthropos, human, and Latin aqua, water) is a human-induced surface horizon that comprises a puddled layer and a plough pan.
Diagnostic criteria An anthraquic horizon is a surface horizon and has: 1. a puddled layer with both: a. a Munsell hue of 7.5 YR or yellower, or GY, B or BG hues; value (moist) of 4 or less; chroma (moist) of 2 or less1; and b. sorted soil aggregates and vesicular pores; and 2. a plough pan underlying the puddled layer with all of the following: a. a platy structure; and b. a bulk density higher by 20 percent or more (relative) than that of the puddled layer; and c. yellowish-brown, brown or reddish-brown iron–manganese mottles or coatings; and 3. a thickness of 20 cm or more.
Field identification An anthraquic horizon shows evidence of reduction and oxidation owing to flooding for part of the year. When not flooded, it is very dispersible and has a loose packing of sorted small aggregates. The plough pan is compact, with platy structure and very slow infiltration. It has yellowish-brown, brown or reddish-brown rust mottles along cracks and root holes.
Anthric horizon General description An anthric horizon (from Greek anthropos, human) is a moderately thick, dark- coloured surface horizon that is the result of long-term cultivation (ploughing, liming, fertilization, etc.).
Diagnostic criteria An anthric horizon2 is a mineral surface horizon and: 1. meets all colour, structure and organic matter requirements of a mollic or umbric horizon; and 1 Colour requirements taken from the Chinese soil taxonomy (CRGCST, 2001). 2 Modified after Krogh and Greve (1999). 214 Chapter 2 – Diagnostic horizons, properties and materials 13
2. shows evidence of human disturbance by having one or more of the following: a. an abrupt lower boundary at ploughing depth, a plough pan; or b. lumps of applied lime; or c. mixing of soil layers by cultivation; or -1 d. 1.5 g kg or more P2O5 soluble in 1-percent citric acid; and 3. has less than 5 percent (by volume) of animal pores, coprolites or other traces of soil animal activity below tillage depth; and 4. has a thickness of 20 cm or more.
Field identification Anthric horizons are associated with old arable lands that have been cultivated for centuries. Signs of mixing or cultivation, evidence of liming (e.g. remnants of applied lime chunks) and their dark colour are the main criteria for recognition.
Relationships with other horizons Anthric horizons can resemble or overlap with mollic or umbric horizons. Anthric horizons may have developed from umbric horizons through human intervention. As they have been limed for a considerable period of time, their base saturation is high. This sets them apart from umbric horizons. The usually low biological activity below tillage depth is uncommon in soils with mollic horizons.
Argic horizon General description The argic horizon (from Latin argilla, white clay) is a subsurface horizon with distinct higher clay content than the overlying horizon. The textural differentiation may be caused by: ÿ an illuvial accumulation of clay; ÿ predominant pedogenetic formation of clay in the subsoil; ÿ destruction of clay in the surface horizon; ÿ selective surface erosion of clay; ÿ upward movement of coarser particles due to swelling and shrinking; ÿ biological activity; ÿ a combination of two or more of these different processes. Sedimentation of surface materials that are coarser than the subsurface horizon may enhance a pedogenetic textural differentiation. However, a mere lithological discontinuity, such as may occur in alluvial deposits, does not qualify as an argic horizon. Soils with argic horizons often have a specific set of morphological, physico-chemical and mineralogical properties other than a mere clay increase. These properties allow various types of argic horizons to be distinguished and their pathways of development to be traced (Sombroek, 1986).
Diagnostic criteria An argic horizon: 1. has a texture of loamy sand or finer and 8 percent or more clay in the fine earth fraction; and 2. one or both of the following: a. has, if an overlying coarser textured horizon is present that is not ploughed and not separated from the argic horizon by a lithological discontinuity, more total clay than this overlying horizon such that: i. if the overlying horizon has less than 15 percent clay in the fine earth fraction, the argic horizon must contain at least 3 percent more clay; or
215 14 World reference base for soil resources 2006
ii. if the overlying horizon has 15 percent or more but less than 40 percent clay in the fine earth fraction, the ratio of clay in the argic horizon to that of the overlying horizon must be 1.2 or more; or iii. if the overlying horizon has 40 percent or more total clay in the fine earth fraction, the argic horizon must contain at least 8 percent more clay; or b. has evidence of clay illuviation in one or more of the following forms: i. oriented clay bridging the sand grains; or ii. clay films lining pores; or iii. clay films on both vertical and horizontal surfaces of soil aggregates; or iv. in thin section, oriented clay bodies that constitute 1 percent or more of the section; or v. a coefficient of linear extensibility (COLE) of 0.04 or higher, and a ratio of fine clay1 to total clay in the argic horizon greater by 1.2 times or more than the ratio in the overlying coarser textured horizon; and 3. has, if an overlying coarser textured horizon is present that is not ploughed and not separated from the argic horizon by a lithological discontinuity, an increase in clay content within a vertical distance of one of the following: a. 30 cm, if there is evidence of clay illuviation; or b. 15 cm; and 4. does not form part of a natric horizon; and 5. has a thickness of one-tenth or more of the sum of the thicknesses of all overlying horizons, if present, and one of the following: a. 7.5 cm or more, if it is not entirely composed of lamellae (that are 0.5 cm or more thick) and the texture is finer than loamy sand; or b. 15 cm or more (combined thickness, if composed entirely of lamellae that are 0.5 cm or more thick).
Field identification Textural differentiation is the main feature for recognition of argic horizons. The illuvial nature may be established using an ×10 hand-lens if clay skins occur on ped surfaces, in fissures, in pores and in channels – illuvial argic horizon should show clay skins on at least 5 percent of both horizontal and vertical ped faces and in the pores. Clay skins are often difficult to detect in shrink–swell soils. The presence of clay skins in protected positions, e.g. in pores, meets the requirements for an illuvial argic horizon.
Additional characteristics The illuvial character of an argic horizon can best be established using thin sections. Diagnostic illuvial argic horizons must show areas with oriented clays that constitute on average at least 1 percent of the entire cross-section. Other tests involved are particle-size distribution analysis, to determine the increase in clay content over a specified depth, and the fine clay/total clay analysis. In illuvial argic horizons, the fine clay to total clay ratio is larger than in the overlying horizons, caused by preferential eluviation of fine clay particles. If the soil shows a lithological discontinuity over or within the argic horizon, or if the surface horizon has been removed by erosion, or if only a plough layer overlies the argic horizon, the illuvial nature must be clearly established.
Relationships with some other diagnostic horizons Argic horizons are normally associated with and situated below eluvial horizons, i.e. horizons from which clay and Fe have been removed. Although initially formed as a
1 Fine clay: < 0.2 μm equivalent diameter. 216 Chapter 2 – Diagnostic horizons, properties and materials 15
subsurface horizon, argic horizons may occur at the surface as a result of erosion or removal of the overlying horizons. Some clay-increase horizons may have the set of properties that characterize the ferralic horizon, i.e. a low CEC and effective CEC (ECEC), a low content of water- dispersible clay and a low content of weatherable minerals, all over a depth of 50 cm. In such cases, a ferralic horizon has preference over an argic horizon for classification purposes. However, an argic horizon prevails if it overlies a ferralic horizon and it has, in its upper part over a depth of 30 cm, 10 percent or more water-dispersible clay, unless the soil material has geric properties or more than 1.4 percent organic carbon. Argic horizons lack the sodium saturation characteristics of the natric horizon. Argic horizons in cool and moist, freely drained soils of high plateaus and mountains in tropical and subtropical regions may occur in association with sombric horizons.
Calcic horizon General description The calcic horizon (from Latin calx, lime) is a horizon in which secondary calcium carbonate (CaCO3) has accumulated in a diffuse form (calcium carbonate present only in the form of fine particles of less than 1 mm, dispersed in the matrix) or as discontinuous concentrations (pseudomycelia, cutans, soft and hard nodules, or veins). The accumulation may be in the parent material or in subsurface horizons, but it can also occur in surface horizons. If the accumulation of soft carbonates becomes such that all or most of the pedological and/or lithological structures disappear and continuous concentrations of calcium carbonate prevail, a hypercalcic qualifier is used.
Diagnostic criteria A calcic horizon has: 1. a calcium carbonate equivalent in the fine earth fraction of 15 percent or more; and 2. 5 percent or more (by volume) secondary carbonates or a calcium carbonate equivalent of 5 percent or more higher (absolute, by mass) than that of an underlying layer; and 3. a thickness of 15 cm or more.
Field identification Calcium carbonate can be identified in the field using a 10-percent hydrochloric acid (HCl) solution. The degree of effervescence (audible only, visible as individual bubbles, or foam-like) is an indication of the amount of lime present. This test is important if only diffuse distributions are present. When foam develops after adding 1 M HCl, it indicates a calcium carbonate equivalent near or more than 15 percent. Other indications for the presence of a calcic horizon are: ÿ white, pinkish to reddish, or grey colours (if not overlapping horizons rich in organic carbon); ÿ a low porosity (interaggregate porosity is usually less than that in the horizon immediately above and, possibly, also less than in the horizon directly underneath). Calcium carbonate content may decrease with depth, but this is difficult to establish in some places, particularly where the calcic horizon occurs in the deeper subsoil. Therefore, accumulation of secondary lime is sufficient to diagnose a calcic horizon.
Additional characteristics Determination of the amount of calcium carbonate (by mass) and the changes within the soil profile of the calcium carbonate content are the main analytical criteria for establishing the presence of a calcic horizon. Determination of the pH (H2O) enables 217 16 World reference base for soil resources 2006
distinction between accumulations with a basic (calcic) character (pH 8.0–8.7) due to
the dominance of CaCO3, and those with an ultrabasic (non-calcic) character (pH > 8.7)
because of the presence of MgCO3 or Na2CO3. In addition, microscopical analysis of thin sections may reveal the presence of dissolution forms in horizons above or below a calcic horizon, evidence of silicate epigenesis (calcite pseudomorphs after quartz), or the presence of other calcium carbonate accumulation structures, while clay mineralogical analyses of calcic horizons often show clays characteristic of confined environments, such as smectite, palygorskite and sepiolite.
Relationships with some other diagnostic horizons When calcic horizons become indurated, transition takes place to the petrocalcic horizon, the expression of which may be massive or platy. In dry regions and in the presence of sulphate-bearing soil or groundwater solutions, calcic horizons occur associated with gypsic horizons. Calcic and gypsic horizons typically (but not everywhere) occupy different positions in the soil profile because of the difference in solubility of calcium carbonate and gypsum, and they can normally be distinguished clearly from each other by the difference in morphology. Gypsum crystals tend to be needle-shaped, often visible to the naked eye, whereas pedogenetic calcium carbonate crystals are much finer in size.
Cambic horizon General description The cambic horizon (from Italian cambiare, to change) is a subsurface horizon showing evidence of alteration relative to the underlying horizons. Diagnostic criteria A cambic horizon: 1. has a texture in the fine earth fraction of very fine sand, loamy very fine sand1, or finer; and 2. has soil structure or absence of rock structure2 in half or more of the volume of the fine earth; and 3. shows evidence of alteration in one or more of the following: a. higher Munsell chroma (moist), higher value (moist), redder hue, or higher clay content than the underlying or an overlying layer; or b. evidence of removal of carbonates3 or gypsum; or c. presence of soil structure and absence of rock structure in the entire fine earth, if carbonates and gypsum are absent in the parent material and in the dust that falls on the soil; and 4. does not form part of a plough layer, does not consist of organic material and does not form part of an anthraquic, argic, calcic, duric, ferralic, fragic, gypsic, hortic, hydragric, irragric, mollic, natric, nitic, petrocalcic, petroduric, petrogypsic, petroplinthic, pisolithic, plaggic, plinthic, salic, sombric, spodic, umbric, terric or vertic horizon; and 5. has a thickness of 15 cm or more.
1 Very fine sand and loamy very fine sand: 50 percent or more of the fraction between 63 and 125 μm. 2 The term rock structure also applies to unconsolidated sediments in which stratification s still visible. 3 A cambic horizon always has less carbonate than an underlying horizon with calcium carbonate accumulation. However, not all primary carbonates have to be leached from a horizon in order for it to qualify as a cambic horizon. If all coarse fragments in the underlying horizon are completely coated with lime, some of these fragments in the cambic horizon are partly free of coatings. If the coarse fragments in the horizon showing calcium carbonate accumulation are coated only on the underside, those in the cambic horizon are free of coatings. 218 Chapter 2 – Diagnostic horizons, properties and materials 17
Relationships with some other diagnostic horizons The cambic horizon can be considered the predecessor of many other diagnostic horizons. All these horizons have specific properties, such as illuvial or residual accumulations, removal of substances other than carbonates or gypsum, accumulation of soluble components, or development of specific soil structure, that are not recognized in the cambic horizon. Cambic horizons in cool and moist, freely drained soils of high plateaus and mountains in tropical and subtropical regions may occur in association with sombric horizons.
Cryic horizon General description The cryic horizon (from Greek kryos, cold, ice) is a perennially frozen soil horizon in mineral or organic materials.
Diagnostic criteria A cryic horizon has: 1. continuously for two or more consecutive years one of the following: a. massive ice, cementation by ice or readily visible ice crystals; or b. a soil temperature of 0 °C or less and insufficient water to form readily visible ice crystals; and 2. a thickness of 5 cm or more.
Field identification Cryic horizons occur in areas with permafrost1 and show evidence of perennial ice segregation, often associated with evidence of cryogenic processes (mixed soil material, disrupted soil horizons, involutions, organic intrusions, frost heave, separation of coarse from fine soil materials, cracks, patterned surface features, such as earth hummocks, frost mounds, stone circles, stripes, nets and polygons) above the cryic horizon or at the soil surface. Soils that contain saline water do not freeze at 0 °C. In order to develop a cryic horizon, such soils must be cold enough to freeze. To identify features of cryoturbation, sorting or thermal contraction, a soil profile should intersect different elements of patterned ground, if any, or be wider than 2 m. Engineers distinguish between warm and cold permafrost. Warm permafrost has a temperature higher than -2 °C and has to be considered unstable. Cold permafrost has a temperature of -2 °C or lower and can be used more safely for construction purposes provided the temperature remains under control.
Relationships with some other diagnostic horizons Cryic horizons may bear characteristics of histic, andic or spodic horizons, and may occur in association with salic, calcic, mollic or umbric horizons. In cold arid regions, yermic horizons may be found in association with cryic horizons.
Duric horizon General description The duric horizon (from Latin durus, hard) is a subsurface horizon showing weakly cemented to indurated nodules or concretions cemented by silica (SiO2), presumably in the form of opal and microcrystalline forms of silica (durinodes). Durinodes often have
1 Permafrost: layer of soil or rock, at some depth beneath the surface, in which the temperature has been continuously below 0 °C for at least some years. It exists where summer heating fails to reach the base of the layer of frozen ground. Arctic Climatology and Meteorology Glossary, National Snow and Ice Data Center, Boulder, USA (http://nsidc.org). 219 18 World reference base for soil resources 2006
carbonate coatings that have to be removed with HCl before slaking the durinodes with potassium hydroxide (KOH).
Diagnostic criteria A duric horizon has: 1. 10 percent or more (by volume) of weakly cemented to indurated, silica- enriched nodules (durinodes) or fragments of a broken-up petroduric horizon that show all of the following: a. when air-dry, less than 50 percent slake in 1 M HCl even after prolonged soaking, but 50 percent or more slake in concentrated KOH, concentrated NaOH or in alternating acid and alkali; and b. are firm or very firm and brittle when wet, both before and after treatment with acid; and c. have a diameter of 1 cm or more; and 2. a thickness of 10 cm or more.
Additional characteristics Dry durinodes do not slake appreciably in water, but prolonged soaking can result in the breaking-off of very thin platelets and in some slaking. In cross-section, most durinodes are roughly concentric, and concentric stringers of opal may be visible under a hand-lens.
Relationships with some other diagnostic horizons In arid regions, duric horizons occur associated with gypsic, petrogypsic, calcic and petrocalcic horizons. In more humid climates, the duric horizon may grade into fragic horizons.
Ferralic horizon General description The ferralic horizon (from Latin ferrum, iron, and alumen, alum) is a subsurface horizon resulting from long and intense weathering in which the clay fraction is dominated by low-activity clays and the silt and sand fractions by highly resistant minerals, such as (hydr)oxides of Fe, Al, Mn and titanium (Ti).
Diagnostic criteria A ferralic horizon: 1. has a sandy loam or finer particle size and less than 80 percent (by volume) gravel, stones, pisoplinthic nodules or petroplinthic gravel; and -1 1 2. has a CEC (by 1 M NH4OAc) of less than 16 cmolc kg clay and an ECEC (sum of exchangeable bases plus exchangeable acidity in 1 M KCl) of less than -1 12 cmolc kg clay; and 3. has less than 10 percent water-dispersible clay, unless it has one or both of the following: a. geric properties; or b. 1.4 percent or more organic carbon; and 4. has less than 10 percent (by grain count) weatherable minerals2 in the 0.05– 0.2 mm fraction; and 1 See Annex 1. 2 Examples of minerals that are included in the meaning of weatherable minerals are all 2:1 phyllosilicates, chlorite, sepiolites, palygorskite, allophane, 1:1 trioctahedral phyllosilicates (serpentines), feldspars, feldspathoids, ferromagnesian minerals, glass, zeolites, dolomite and apatite. The intent of the term weatherable minerals is to include those minerals that are unstable in humid climates compared with other minerals, such as quartz and 1:1 lattice clays, but that are more resistant to weathering than calcite (Soil Survey Staff 2003). 220 Chapter 2 – Diagnostic horizons, properties and materials 19
5. does not have andic or vitric properties; and 6. has a thickness of 30 cm or more.
Field identification Ferralic horizons are associated with old and stable landforms. The macrostructure seems to be moderate to weak at first sight but typical ferralic horizons have a strong microaggregation. The consistence is usually friable; the disrupted, dry soil material flows like flour between the fingers. Lumps of ferralic horizons are usually relatively light in mass because of the low bulk density; many ferralic horizons give a hollow sound when tapped, indicating high porosity. Illuviation and stress features such as clay skins and pressure faces are generally lacking. Boundaries of a ferralic horizon are normally diffuse and little differentiation in colour or particle-size distribution within the horizon can be detected. Texture is sandy loam or finer in the fine earth fraction; gravel, stones, pisoplinthic nodules or petroplinthic gravel comprise less than 80 percent (by volume).
Additional characteristics As an alternative to the weatherable minerals requirement, a total reserve of bases (TRB = exchangeable plus mineral calcium [Ca], magnesium [Mg], potassium [K] and sodium -1 [Na]) of less than 25 cmolc kg soil may be indicative.
Relationships with some other diagnostic horizons Ferralic horizons may meet the clay increase requirements that characterize the argic horizon. If the upper 30 cm of the horizon showing a clay increase contains 10 percent or more water-dispersible clay, an argic horizon has preference over a ferralic horizon for classification purposes, unless the soil material has geric properties or more than 1.4 percent organic carbon.
Acid ammonium oxalate (pH 3) extractable Fe, Al and silicon (Alox, Feox, Siox) in ferralic horizons are very low, which sets them apart from the nitic horizons and layers with andic or vitric properties. Nitic horizons have a significant amount of active iron oxides: more than 0.2 percent acid oxalate (pH 3) extractable Fe from the fine earth fraction which, in addition, is more than 5 percent of the citrate-dithionite extractable
Fe. Vitric properties require an Alox + ½Feox content of at least 0.4 percent, and andic properties at least 2 percent. The interface with the cambic horizon is formed by the CEC/ECEC/weatherable mineral requirements. Some cambic horizons have a low CEC; however, the amount of weatherable minerals (or, alternatively, the TRB) is too high for a ferralic horizon. Such horizons represent an advanced stage of weathering and form the transition between the cambic and the ferralic horizon. Ferralic horizons in cool and moist, freely drained soils of high plateaus and mountains in tropical and subtropical regions may occur in association with sombric horizons.
Ferric horizon General description The ferric horizon (from Latin ferrum, iron) is one in which segregation of Fe, or Fe and manganese (Mn), has taken place to such an extent that large mottles or discrete nodules have formed and the intermottle/internodular matrix is largely depleted of Fe. Generally, such segregation leads to poor aggregation of the soil particles in Fe- depleted zones and compaction of the horizon.
Diagnostic criteria A ferric horizon has: 221 20 World reference base for soil resources 2006
1. one or both of the following: a. 15 percent or more of the exposed area occupied by coarse mottles with a Munsell hue redder than 7.5 YR and a chroma of more than 5, moist; or b. 5 percent or more of the volume consisting of discrete reddish to blackish nodules with a diameter of 2 mm or more, with at least the exteriors of the nodules being at least weakly cemented or indurated and the exteriors having redder hue or stronger chroma than the interiors; and 2. less than 40 percent of the volume consisting of strongly cemented or indurated nodules and an absence of continuous, fractured or broken sheets; and 3. less than 15 percent consisting of firm to weakly cemented nodules or mottles that change irreversibly to strongly cemented or indurated nodules or mottles on exposure to repeated wetting and drying with free access of oxygen; and 4. a thickness of 15 cm or more.
Relationships with some other diagnostic horizons If the amount of weakly-cemented nodules or mottles reaches 15 percent or more (by volume) and these harden irreversibly to hard nodules or a hardpan or to irregular aggregates on exposure to repeated wetting and drying with free access of oxygen, the horizon is considered to be a plinthic horizon. Therefore, ferric horizons may, in tropical or subtropical regions, grade laterally into plinthic horizons. If the amount of hard nodules reaches 40 percent or more, it is a pisoplinthic horizon.
Folic horizon General description The folic horizon (from Latin folium, leaf) is a surface horizon, or a subsurface horizon occurring at shallow depth, that consists of well-aerated organic material.
Diagnostic criteria A folic horizon consists of organic material that: a. is saturated with water for less than 30 consecutive days in most years; and b. has a thickness of 10 cm or more.
Relationships with some other diagnostic horizons Histic horizons have similar characteristics to the folic horizon; however, these are saturated with water for one month or more in most years. Moreover, the composition of the histic horizon is generally different from that of the folic horizon as the vegetative cover is often different.
Fragic horizon General description The fragic horizon (from Latin frangere, to break) is a natural non-cemented subsurface horizon with pedality and a porosity pattern such that roots and percolating water penetrate the soil only along interped faces and streaks. The natural character excludes plough pans and surface traffic pans.
Diagnostic criteria A fragic horizon: 1. shows evidence of alteration1, at least on the faces of structural units; separations between these units, which allow roots to enter, have an average horizontal spacing of 10 cm or more; and 2. contains less than 0.5 percent (by mass) organic carbon; and
1 As defined in the cambic horizon. 222 Chapter 2 – Diagnostic horizons, properties and materials 21
3. shows in 50 percent or more of the volume slaking or fracturing of air-dry clods, 5–10 cm in diameter, within 10 minutes when placed in water; and 4. does not cement upon repeated wetting and drying; and 5. has a penetration resistance at field capacity of 50 kPa or more in 90 percent or more of the volume; and 6. does not show effervescence after adding a 10-percent HCl solution; and 7. has a thickness of 15 cm or more.
Field identification A fragic horizon has a prismatic and/or blocky structure. The inner parts of the prisms may have a relatively high total porosity (including pores larger than 200 mm) but, as a result of a dense outer rim, there is no continuity between the intraped pores and the interped pores and fissures. The result is a closed box system with 90 percent or more of the soil volume that cannot be explored by roots and is isolated from percolating water. It is essential that the required soil volume be measured from both vertical and horizontal sections; horizontal sections often reveal polygonal structures. Three or four such polygons (or a cut up to 1 m2) are sufficient to test the volumetric basis for the definition of the fragic horizon. The ped interface can have the colour, mineralogical and chemical characteristics of an eluvial or albic horizon, or meet the requirements of albeluvic tonguing. In the presence of a fluctuating water table, this part of the soil is depleted of Fe and Mn. A concomitant Fe accumulation is observed at the level of the ped surface and Mn accumulations will occur further inside the peds (stagnic colour pattern). Fragic horizons are commonly loamy, but loamy sand and clay textures are not excluded. In the latter case, the clay mineralogy is dominantly kaolinitic. Dry clods are hard to extremely hard; moist clods are firm to extremely firm; moist consistence may be brittle. A ped or clod from a fragic horizon tends to rupture suddenly under pressure rather than to undergo slow deformation. The fragic horizon has little active faunal activity except, occasionally, between the polygons.
Relationships with some other diagnostic horizons A fragic horizon may underlie, although not necessarily directly, an albic, cambic, spodic or argic horizon, unless the soil has been truncated. It can overlap partly or completely with an argic horizon. Laterally, fragic horizons may grade into (petro-) duric horizons in dry regions. Moreover, fragic horizons can have reducing conditions and a stagnic colour pattern.
Fulvic horizon General description The fulvic horizon (from Latin fulvus, dark yellow) is a thick, dark-brown horizon at or near to the surface that is typically associated with short-range-order minerals (commonly allophane) or with organo-aluminium complexes. It has a low bulk density and contains highly humified organic matter that shows a lower ratio of humic acids to fulvic acids compared with the melanic horizon.
Diagnostic criteria A fulvic horizon has: 1. andic properties; and 2. one or both of the following: a. Munsell colour value or chroma (moist) of more than 2; or
223 22 World reference base for soil resources 2006
b. melanic index1 of 1.70 or more; and 3. a weighted average of 6 percent or more organic carbon, and 4 percent or more organic carbon in all parts; and 4. a cumulative thickness of 30 cm or more with less than 10 cm non-fulvic material in between.
Field identification When dark brown, the fulvic horizon is easily identifiable by its colour, thickness, as well as its typical, although not exclusive2, association with pyroclastic deposits. Distinction between the blackish coloured fulvic and melanic horizons is made after determining the melanic index, which requires laboratory analyses.
Gypsic horizon General description The gypsic horizon (from Greek gypsos) is a commonly non-cemented horizon
containing secondary accumulations of gypsum (CaSO4.2H2O) in various forms. If the accumulation of gypsum becomes such that all or most of the pedological and/or lithological structures disappear and continuous concentrations of gypsum prevail, a hypergypsic qualifier is used.
Diagnostic criteria A gypsic horizon has: 1. 5 percent3 or more gypsum and 1 percent or more (by volume) of visible secondary gypsum; and 2. a product of thickness (in centimetres) times gypsum content (percentage) of 150 or more; and 3. a thickness of 15 cm or more.
Field identification Gypsum occurs as pseudomycelia, as coarse crystals, as nests, beards or coatings, as elongated groupings of fibrous crystals, or as powdery accumulations. The last form gives the gypsic horizon a massive structure. The distinction between compact powdery accumulations and the others is important in terms of soil capability. Gypsum crystals may be mistaken for quartz. Gypsum is soft and can easily be broken between thumbnail and forefinger. Quartz is hard and cannot be broken except by hammering. Gypsic horizons may be associated with calcic horizons but usually occur in separate positions within the soil profile, because of the higher solubility of gypsum compared with lime.
Additional characteristics Determination of the amount of gypsum in the soil to verify the required content and increase, as well as thin section analysis, is helpful to establish the presence of a gypsic horizon and the distribution of the gypsum in the soil mass.
Relationships with some other diagnostic horizons When gypsic horizons become indurated, transition takes place to the petrogypsic horizon, the expression of which may be as massive or platy structures.
1 See Annex 1. 2 Fulvic horizons may also be found in aluandic-type of soils derived from other material than pyroclastics. 3 -1 The percentage gypsum is calculated as the product of gypsum content, expressed as cmolc kg soil, and the equivalent mass of gypsum (86) expressed as a percentage. 224 Chapter 2 – Diagnostic horizons, properties and materials 23
In dry regions, gypsic horizons are associated with calcic or salic horizons. Calcic and gypsic horizons usually occupy distinct positions in the soil profile as the solubility of calcium carbonate is different from that of gypsum. They normally can be distinguished clearly from each other by the morphology (see calcic horizon). Salic and gypsic horizons also occupy different positions for the same reasons.
Histic horizon General description The histic horizon (from Greek histos, tissue) is a surface horizon, or a subsurface horizon occurring at shallow depth, that consists of poorly aerated organic material.
Diagnostic criteria A histic horizon consists of organic material that: 1. is saturated with water for 30 consecutive days or more in most years (unless drained); and 2. has a thickness of 10 cm or more. If the layer with organic material is less than 20 cm thick, the upper 20 cm of the soil after mixing, or if continuous rock is present within 20 cm depth, the entire soil above after mixing, must contain 20 percent or more organic carbon.
Relationships with some other diagnostic horizons The folic horizon has similar characteristics to the histic horizon; however, the folic horizon is saturated with water for less than one month in most years. Moreover, the composition of the histic horizon is generally different from that of the folic horizon as the vegetative cover is often different. The lower limit of organic carbon content, varying from 12 percent (20 percent organic matter) to 18 percent organic carbon (30 percent organic matter), sets the histic horizon apart from mollic or umbric horizons, which have these contents as upper limits. Histic horizons with less than 25 percent organic carbon may have andic or vitric properties.
Hortic horizon General description A hortic horizon (from Latin hortus, garden) is a human-induced mineral surface horizon that results from deep cultivation, intensive fertilization and/or long- continued application of human and animal wastes and other organic residues (e.g. manures, kitchen refuse, compost and night soil).
Diagnostic criteria A hortic horizon is a mineral surface horizon and has: 1. a Munsell colour value and chroma (moist) of 3 or less; and 2. a weighted average organic carbon content of 1 percent or more; and 1 -1 3. a 0.5 M NaHCO3 extractable P2O5 content of 100 mg kg fine earth or more in the upper 25 cm2; and
4. a base saturation (by 1 M NH4OAc) of 50 percent or more; and 5. 25 percent (by volume) or more of animal pores, coprolites or other traces of soil animal activity; and 6. a thickness of 20 cm or more.
1 Known as the Olsen routine method (Olsen et al., 1954). 2 Gong et al., 1997. 225 24 World reference base for soil resources 2006
Field identification The hortic horizon is thoroughly mixed. Potsherds and other artefacts are common although often abraded. Tillage marks or evidence of mixing of the soil can be present.
Relationships with some other diagnostic horizons Hortic horizons closely resemble mollic horizons. Therefore, the human influence must be clearly established in order to separate the two diagnostic horizons.
Hydragric horizon General description A hydragric horizon (from Greek hydor, water, and Latin ager, field) is a human- induced subsurface horizon associated with wet cultivation.
Diagnostic criteria A hydragric horizon is associated with wet cultivation and has: 1. one or more of the following: a. Fe or Mn coatings or Fe or Mn concretions; or b. dithionite-citrate extractable Fe 2 times or more, or dithionite-citrate extractable Mn 4 times or more that of the surface horizon; or c. redox depleted zones with a Munsell colour value 4 or more and a chroma of 2 or less (both moist) in macropores; and 2. a thickness of 10 cm or more.
Field identification The hydragric horizon occurs below the puddled layer and the plough pan. It has either reduction features in pores, such as coatings or halos with a colour hue of 2.5 Y or yellower and a chroma (moist) of 2 or less, or segregations of Fe and/or Mn in the matrix as a result of the oxidative environment. It usually shows grey clay-fine silt and clay-silt-humus cutans on ped faces.
Irragric horizon General description The irragric horizon (from Latin irrigare, to irrigate, and ager, field) is a human- induced mineral surface horizon that builds up gradually through continuous application of irrigation water with substantial amounts of sediments, and which may include fertilizers, soluble salts, organic matter, etc.
Diagnostic criteria An irragric horizon is a mineral surface horizon and has: 1. a uniformly structured surface layer; and 2. a higher clay content, particularly fine clay, than the underlying original soil; and 3. relative differences among medium, fine and very fine sand, clay and carbonates less than 20 percent among parts within the horizon; and 4. a weighted average organic carbon content of 0.5 percent or more, decreasing with depth but remaining at 0.3 percent or more at the lower limit of the irragric horizon; and 5. 25 percent (by volume) or more of animal pores, coprolites or other traces of soil animal activity; and 6. a thickness of 20 cm or more.
226 Chapter 2 – Diagnostic horizons, properties and materials 25
Field identification Soils with an irragric horizon show evidence of surface raising, which may be inferred either from field observation or from historical records. The irragric horizon shows evidence of considerable biological activity. The lower boundary is clear and irrigation deposits or buried soils may be present below.
Relationships with some other diagnostic horizons Irragric horizons differ from fluvic materials in lacking evidence of stratification owing to continuous ploughing.
Melanic horizon General description The melanic horizon (from Greek melas, black) is a thick, black horizon at or near the surface, which is typically associated with short-range-order minerals (commonly allophane) or with organo-aluminium complexes. It has a low bulk density and contains highly humified organic matter that shows a lower ratio of fulvic acids to humic acids compared with the fulvic horizon.
Diagnostic criteria A melanic horizon has: 1. andic properties; and 2. a Munsell colour value and chroma (both moist) of 2 or less, and 3. a melanic index1 of less than 1.70; and 4. a weighted average of 6 percent or more organic carbon, and 4 percent or more organic carbon in all parts; and 5. a cumulative thickness of 30 cm or more with less than 10 cm non-melanic material in between.
Field identification The intense dark colour, its thickness, as well as its common association with pyroclastic deposits help to recognize the melanic horizon in the field. However, laboratory analyses to determine the type of organic matter may be necessary to identify the melanic horizon unambiguously.
Mollic horizon General description The mollic horizon (from Latin mollis, soft) is a well-structured, dark-coloured surface horizon with a high base saturation and a moderate to high content of organic matter.
Diagnostic criteria A mollic horizon, after mixing either the upper 20 cm of the mineral soil or, if continuous rock, a cryic, petrocalcic, petroduric, petrogypsic or petroplinthic horizon is present within 20 cm of the mineral soil surface, the entire mineral soil above, has: 1. a soil structure sufficiently strong that the horizon is not both massive and hard or very hard when dry in both the mixed part and the underlying unmixed part if the minimum thickness is larger than 20 cm (prisms larger than 30 cm in diameter are included in the meaning of massive if there is no secondary structure within the prisms); and 2. Munsell colours with a chroma of 3 or less when moist, a value of 3 or less when moist and 5 or less when dry on broken samples in both the mixed part and the underlying unmixed part if the minimum thickness is greater than 20 cm. If
1 See Annex 1. 227 26 World reference base for soil resources 2006
there is 40 percent or more finely divided lime, the limits of dry colour value are waived; the colour value, moist, is 5 or less. The colour value is one unit or more darker than that of the parent material (both moist and dry), unless the parent material has a colour value of 4 or less, moist, in which case the colour contrast requirement is waived. If a parent material is not present, comparison must be made with the layer immediately underlying the surface layer; and 3. an organic carbon content of 0.6 percent or more in both the mixed part and the underlying unmixed part if the minimum thickness is larger than 20 cm. The organic carbon content is 2.5 percent or more if the colour requirements are waived because of finely divided lime, or 0.6 percent more than in the parent material if the colour requirements are waived because of dark coloured parent materials; and
4. a base saturation (by 1 M NH4OAc) of 50 percent or more on a weighted average throughout the depth of the horizon; and 5. a thickness of one of the following: a. 10 cm or more if directly overlying continuous rock, or a cryic, petrocalcic, petroduric, petrogypsic or petroplinthic horizon; or b. 20 cm or more and one-third or more of the thickness between the soil surface and the upper boundary of continuous rock, or a calcic, cryic, gypsic, petrocalcic, petroduric, petrogypsic, petroplinthic or salic horizon or calcaric, fluvic or gypsyric material within 75 cm; or c. 20 cm or more and one-third or more of the thickness between the soil surface and the lower boundary of the lowest diagnostic horizon within 75 cm and, if present, above any of the diagnostic horizons listed under b.; or d. 25 cm or more.
Field identification A mollic horizon may easily be identified by its dark colour, caused by the accumulation of organic matter, well-developed structure (usually a granular or fine
subangular blocky structure), an indication of high base saturation (e.g. pHwater > 6), and its thickness.
Relationships with some other diagnostic horizons The base saturation of 50 percent separates the mollic horizon from the umbric horizon, which is otherwise similar. The upper limit of organic carbon content varies from 12 percent (20 percent organic matter) to 18 percent organic carbon (30 percent organic matter), which is the lower limit for the histic horizon, or 20 percent, the lower limit for a folic horizon. A special type of mollic horizon is the voronic horizon. It has a higher organic carbon content (1.5 percent or more), a specific structure (granular or fine subangular blocky), a very dark colour in its upper part, a high biological activity, and a minimum thickness of 35 cm.
Natric horizon General description The natric horizon (from Arabic natroon, salt) is a dense subsurface horizon with distinct higher clay content than the overlying horizon or horizons. It has a high content in exchangeable Na and/or Mg.
Diagnostic criteria A natric horizon: 1. has a texture of loamy sand or finer and 8 percent or more clay in the fine earth fraction; and 228 Chapter 2 – Diagnostic horizons, properties and materials 27
2. one or both of the following: a. has, if an overlying coarser textured horizon is present that is not ploughed and not separated from the natric horizon by a lithological discontinuity, more clay than this overlying horizon such that: i. if the overlying horizon has less than 15 percent clay in the fine earth fraction, the natric horizon must contain at least 3 percent more clay; or ii. if the overlying horizon has 15 percent or more and less than 40 percent clay in the fine earth fraction, the ratio of clay in the natric horizon to that of the overlying horizon must be 1.2 or more; or iii. if the overlying horizon has 40 percent or more clay in the fine earth fraction, the natric horizon must contain at least 8 percent more clay; or b. has evidence of clay illuviation in one or more of the following forms: i. oriented clay bridging the sand grains; or ii. clay films lining pores; or iii. clay films on both vertical and horizontal surfaces of soil aggregates; or iv. in thin sections, oriented clay bodies that constitute 1 percent or more of the section; or v. a COLE of 0.04 or higher, and a ratio of fine clay1 to total clay in the natric horizon greater by 1.2 times or more than the ratio in the overlying coarser textured horizon; and 3. has, if an overlying coarser textured horizon is present that is not ploughed and not separated from the natric horizon by a lithological discontinuity, an increase in clay content within a vertical distance of 30 cm; and 4. has one or more of the following: a. a columnar or prismatic structure in some part of the horizon; or b. a blocky structure with tongues of an overlying coarser textured horizon in which there are uncoated silt or sand grains, extending 2.5 cm or more into the natric horizon; or c. a massive appearance; and 5. has an exchangeable Na percentage (ESP2) of 15 or more within the upper 40 cm, or more exchangeable Mg plus Na than Ca plus exchange acidity (at pH 8.2) within the same depth if the saturation with exchangeable Na is 15 percent or more in some subhorizon within 200 cm of the soil surface; and 6. has a thickness of one-tenth or more of the sum of the thicknesses of all overlying horizons, if present, and one of the following: a. 7.5 cm or more, if it is not entirely composed of lamellae (that are 0.5 cm or more thick) and the texture is finer than loamy sand; or b. 15 cm or more (combined thickness, if composed entirely of lamellae that are 0.5 cm or more thick).
Field identification The colour of the natric horizon ranges from brown to black, especially in the upper part. The structure is coarse columnar or prismatic, sometimes blocky or massive. Rounded and often whitish tops of the structural elements are characteristic. Both colour and structural characteristics depend on the composition of the exchangeable cations and the soluble salt content in the underlying layers. Often, thick and dark-coloured clay coatings occur, especially in the upper part of the horizon. Natric horizons have a poor aggregate stability and very low permeability under wet conditions. When dry, the natric horizon becomes hard to extremely hard. Soil reaction is strongly alkaline; pH (H2O) is more than 8.5.
1 Fine clay: < 0.2 µm equivalent diameter. 2 ESP = exchangeable Na × 100/CEC (at pH 7). 229 28 World reference base for soil resources 2006
Additional characteristics
Natric horizons are characterized by a high pH (H2O), which is frequently more than 9.0. Another measure to characterize the natric horizon is the sodium adsorption ratio (SAR), which has to be 13 or more. The SAR is calculated from soil solution data (Na+, 2+ 2+ + 2+ 2+ 0.5 Ca , Mg given in mmolc/litre): SAR = Na /[(Ca + Mg )/2] . Micromorphologically, natric horizons show a specific fabric. The peptized plasma shows a strong orientation in a mosaic or parallel-striated pattern. The plasma separations also show a high content in associated humus. Microcrusts, cutans, papules and infillings appear when the natric horizon is impermeable.
Relationships with some other diagnostic horizons A surface horizon usually rich in organic matter overlies the natric horizon. This horizon of humus accumulation varies in thickness from a few centimetres to more than 25 cm, and may be a mollic horizon. An albic horizon may be present between the surface and the natric horizon. Frequently, a salt-affected layer occurs below the natric horizon. The salt influence may extend into the natric horizon, which besides being sodic then also becomes saline. Salts present may be chlorides, sulphates or carbonates/bicarbonates.
The humus-illuvial part of natric horizons has a base saturation (by 1 M NH4OAc) of more than 50 percent, which separates it from the sombric horizon.
Nitic horizon General description The nitic horizon (from Latin nitidus, shiny) is a clay-rich subsurface horizon. It has moderately to strongly developed polyhedric or nutty structure with many shiny ped faces, which cannot or can only partially be attributed to clay illuviation.
Diagnostic criteria A nitic horizon has: 1. less than 20 percent change (relative) in clay content over 12 cm to layers immediately above and below; and 2. all of the following: a. 30 percent or more clay; and b. a water-dispersible clay to total clay ratio less than 0.10; and c. a silt to clay ratio less than 0.40; and 3. moderate to strong, angular blocky structure breaking to flat-edged or nut- shaped elements with shiny ped faces. The shiny faces are not, or are only partially, associated with clay coatings; and 4. all of the following: a. 4.0 percent or more citrate-dithionite extractable Fe (free iron) in the fine earth fraction; and b. 0.20 percent or more acid oxalate (pH 3) extractable Fe (active iron) in the fine earth fraction; and c. a ratio between active and free iron of 0.05 or more; and 5. a thickness of 30 cm or more.
Field identification A nitic horizon has a clay loam or finer texture but feels loamy. The change in clay content with the overlying and underlying horizons is gradual. Similarly, there is no abrupt colour change with the horizons above and below. The colours are of low value and chroma with hues often 2.5 YR, but sometimes redder or yellower. The structure is moderate to strong angular blocky, breaking to flat-edged or nut-shaped elements showing shiny faces. 230 Chapter 2 – Diagnostic horizons, properties and materials 29
Additional characteristics -1 In many nitic horizons, the CEC (by 1 M NH4OAc) is less than 36 cmolc kg clay, -1 1 or even less than 24 cmolc kg clay . The ECEC (sum of exchangeable bases plus exchangeable acidity in 1 M KCl) is about half of the CEC. The moderate to low CEC and ECEC reflect the dominance of 1:1 lattice clays (either kaolinite and/or [meta]halloysite).
Relationships with some other diagnostic horizons The nitic horizon may be considered as a special type of argic horizon, or a strongly expressed cambic horizon, with specific properties such as a low amount of water- dispersible clay and a high amount of active iron. As such, the nitic horizon has preference over both for classification purposes. Its mineralogy (kaolinitic/ [meta]halloysitic) sets it apart from most vertic horizons, which have dominantly a smectitic mineralogy. However, nitic horizons may grade laterally into vertic horizons in lower landscape positions. The well-expressed soil structure, the high amount of active iron, and the frequently intermediate CEC in nitic horizons set them apart from ferralic horizons. Nitic horizons in cool and moist, freely drained soils of high plateaus and mountains in tropical and subtropical regions may occur in association with sombric horizons.
Petrocalcic horizon General description A petrocalcic horizon (from Greek petros, rock, and Latin calx, lime) is an indurated calcic horizon that is cemented by calcium carbonate and, in places, by calcium and some magnesium carbonate. It is either massive or platy in nature, and extremely hard.
Diagnostic criteria A petrocalcic horizon has: 1. very strong effervescence after adding a 10-percent HCl solution; and 2. induration or cementation, at least partially by secondary carbonates, to the extent that air-dry fragments do not slake in water and roots cannot enter except along vertical fractures (which have an average horizontal spacing of 10 cm or more and which occupy less than 20 percent [by volume] of the layer); and 3. extremely hard consistence when dry, so that it cannot be penetrated by spade or auger; and 4. a thickness of 10 cm or more, or 1 cm or more if it is laminar and rests directly on continuous rock.
Field identification Petrocalcic horizons occur as non-platy calcrete (either massive or nodular) or as platy calcrete, of which the following types are the most common: ÿ Lamellar calcrete: superimposed, separate, petrified layers varying in thickness from a few millimetres to several centimetres. The colour is generally white or pink. ÿ Petrified lamellar calcrete: one or several extremely hard layers, grey or pink in colour. They are generally more cemented than the lamellar calcrete and very massive (no fine lamellar structures, but coarse lamellar structures may be present). Non-capillary pores in petrocalcic horizons are filled, and the hydraulic conductivity is moderately slow to very slow.
1 See Annex 1. 231 30 World reference base for soil resources 2006
Relationships with some other diagnostic horizons In arid regions, petrocalcic horizons may occur in association with (petro-) duric horizons, into which they may grade laterally. The cementing agent differentiates petrocalcic and duric horizons. In petrocalcic horizons, calcium and some magnesium carbonate constitute the main cementing agent while some accessory silica may be present. In duric horizons, silica is the main cementing agent, with or without calcium carbonate. Petrocalcic horizons also occur in association with gypsic or petrogypsic horizons.
Petroduric horizon General description A petroduric horizon (from Greek petros, rock, and Latin durus, hard), also known as duripan or dorbank (South Africa), is a subsurface horizon, usually reddish or reddish
brown in colour, that is cemented mainly by secondary silica (SiO2, presumably opal and microcrystalline forms of silica). Air-dry fragments of petroduric horizons do not slake in water, even after prolonged wetting. Calcium carbonate may be present as accessory cementing agent.
Diagnostic criteria A petroduric horizon has: 1. induration or cementation in 50 percent or more of some subhorizon; and 2. evidence of silica accumulation (opal or other forms of silica), e.g. as coatings in some pores, on some structural faces or as bridges between sand grains; and 3. when air-dry, less than 50 percent slakes in 1 M HCl even after prolonged soaking, but 50 percent or more slake in concentrated KOH, concentrated NaOH or in alternating acid and alkali; and 4. a lateral continuity such that roots cannot penetrate except along vertical fractures (which have an average horizontal spacing of 10 cm or more and which occupy less than 20 percent [by volume] of the layer); and 5. a thickness of 1 cm or more.
Field identification A petroduric horizon has a very to extremely firm consistence when moist, and is very or extremely hard when dry. Effervescence after applying 1 M HCl may take place, but is probably not as vigorous as in petrocalcic horizons, which appear similar. However, it may occur in conjunction with a petrocalcic horizon.
Relationships with some other diagnostic horizons In dry and arid climates, petroduric horizons may grade laterally into petrocalcic horizons, and/or occur in conjunction with calcic or gypsic horizons, which they normally overlie. In more humid climates, petroduric horizons may grade laterally into fragic horizons.
Petrogypsic horizon General description A petrogypsic horizon (from Greek petros, rock, and gypsos) is a cemented horizon
containing secondary accumulations of gypsum (CaSO4.2H2O).
Diagnostic criteria A petrogypsic horizon has: 1. 5 percent1 or more gypsum and 1 percent or more (by volume) visible secondary gypsum; and
1 -1 The percentage gypsum is calculated as the product of gypsum content, expressed as cmolc kg soil, and the equivalent mass of gypsum (86) expressed as a percentage. 232 Chapter 2 – Diagnostic horizons, properties and materials 31
2. induration or cementation by secondary gypsum, at least partially, to the extent that air-dry fragments do not slake in water and that it cannot be penetrated by roots except along vertical fractures (which have an average horizontal spacing of 10 cm or more and which occupy less than 20 percent [by volume] of the layer); and 3. a thickness of 10 cm or more.
Field identification Petrogypsic horizons are hard, whitish and composed predominantly of gypsum. They may be capped by a thin, laminar layer about 1 cm thick.
Additional characteristics Determinations of the amount of gypsum in the soil to verify the required content and increase, as well as thin section analysis, are helpful techniques to establish the presence of a petrogypsic horizon and the distribution of the gypsum in the soil mass. In thin sections, the petrogypsic horizon shows a compacted microstructure with only a few cavities. The matrix is composed of densely packed lenticular gypsum crystals mixed with small amounts of detrital material. The matrix has a faint yellow colour in plain light. Irregular nodules formed by colourless transparent zones consist of coherent crystal aggregates with a hypidiotopic or xenotopic fabric and are mostly associated with pores or former pores. Traces of biological activity (pedotubules) are sometimes visible.
Relationships with some other diagnostic horizons As the petrogypsic horizon develops from a gypsic horizon, the two are closely linked. Petrogypsic horizons frequently occur associated with calcic horizons. Calcic and gypsic accumulations usually occupy different positions in the soil profile because the solubility of calcium carbonate is different from that of gypsum. Normally, they can be distinguished clearly from each other by their morphology (see calcic horizon).
Petroplinthic horizon General description A petroplinthic horizon (from Greek petros, rock, and plinthos, brick) is a continuous, fractured or broken layer of indurated material, in which Fe (and in cases also Mn) is an important cement and in which organic matter is either absent or present only in traces.
Diagnostic criteria A petroplinthic horizon: 1. is a continuous, fractured or broken sheet of connected, strongly cemented to indurated a. reddish to blackish nodules; or b. reddish, yellowish to blackish mottles in platy, polygonal or reticulate patterns; and 2. has a penetration resistance1 of 4.5 MPa or more in 50 percent or more of the volume; and 3. has a ratio between acid oxalate (pH 3) extractable Fe and citrate-dithionite extractable Fe of less than 0.102; and 4. has a thickness of 10 cm or more.
1 Asiamah (2000). From this point onwards, the horizon will start hardening irreversibly. 2 Estimated from data given by Varghese and Byju (1993). 233 32 World reference base for soil resources 2006
Field identification Petroplinthic horizons are extremely hard; typically rusty brown to yellowish brown; either massive, or show an interconnected nodular, or a reticulate, platy or columnar pattern that encloses non-indurated material. They may be fractured or broken.
Relationships with some other diagnostic horizons Petroplinthic horizons are closely associated with plinthic horizons from which they develop. In some places, plinthic horizons can be traced by following petroplinthic layers, which have formed, for example, in road cuts. The low ratio between acid oxalate (pH 3) extractable Fe and citrate-dithionite extractable Fe separates the petroplinthic horizon from thin iron pans, bog iron and indurated spodic horizons as occurring in, for example, Podzols, which in addition contain a fair amount of organic matter.
Pisoplinthic horizon General description A pisoplinthic horizon (from Latin pisum, pea, and Greek plinthos, brick) contains nodules that are strongly cemented to indurated with Fe (and in some cases also with Mn).
Diagnostic criteria A pisoplinthic horizon has: 1. 40 percent or more of the volume occupied by discrete, strongly cemented to indurated, reddish to blackish nodules with a diameter of 2 mm or more; and 2. a thickness of 15 cm or more.
Relationships with some other diagnostic horizons A pisoplinthic horizon results if a plinthic horizon hardens in the form of discrete nodules. The hardness and the amount of the nodules separate it also from the ferric horizon.
Plaggic horizon General description A plaggic horizon (from Dutch plag, sod) is a black or brown human-induced mineral surface horizon that has been produced by long-continued manuring. In medieval times, sod and other materials were commonly used for bedding livestock and the manure was spread on fields being cultivated. The mineral materials brought in by this kind of manuring eventually produced an appreciably thickened horizon (in places as much as 100 cm or more thick) that is rich in organic carbon. Base saturation is typically low.
Diagnostic criteria A plaggic horizon is a mineral surface horizon and: 1. has a texture of sand, loamy sand, sandy loam or loam, or a combination of them; and 2. contains artefacts, but less than 20 percent, or has spade marks below 30 cm depth; and 3. has Munsell colours with a value of 4 or less, moist, 5 or less, dry, and a chroma of 2 or less, moist; and 4. has an organic carbon content of 0.6 percent or more; and 5. occurs in locally raised land surfaces; and 6. has a thickness of 20 cm or more.
234 Chapter 2 – Diagnostic horizons, properties and materials 33
Field identification The plaggic horizon has brownish or blackish colours, related to the origin of source materials. Its reaction is slightly to strongly acid. It shows evidence of agricultural operations such as spade marks as well as old cultivation layers. Plaggic horizons commonly overlie buried soils although the original surface layers may be mixed. The lower boundary is typically clear.
Additional characteristics The texture is in most cases sand or loamy sand. Sandy loam and silt loam are rare.
The P2O5 content (extractable in 1-percent citric acid) in plaggic horizons may be high, often more than 0.25 percent within 20 cm of the surface, but frequently more than 1 percent. Owing to the abandonment of the practice, phosphate contents may have lowered considerably, and can no longer be seen as diagnostic for the plaggic horizon.
Relationships with some other diagnostic horizons Few soil characteristics differentiate the terric and plaggic horizons from each other. Terric horizons usually show a high biological activity, have a neutral to slightly alkaline soil reaction (pH [H2O] is normally more than 7.0), and may contain free lime. The colour is strongly related to the source material or the underlying substrate. Buried soils may be observed at the base of the horizon although mixing can obscure the contact. The plaggic horizon has many characteristics in common with umbric horizons, and evidence of human influences, such as the spade marks or surface raising, is often required to distinguish between the two.
Plinthic horizon General description A plinthic horizon (from Greek plinthos, brick) is a subsurface horizon that consists of an Fe-rich (in some cases also Mn-rich), humus-poor mixture of kaolinitic clay (and other products of strong weathering, such as gibbsite) with quartz and other constituents, and which changes irreversibly to a layer with hard nodules, a hardpan or irregular aggregates on exposure to repeated wetting and drying with free access of oxygen.
Diagnostic criteria A plinthic horizon has: 1. within 15 percent or more of the volume single or in combination: a. discrete nodules that are firm to weakly cemented, with a redder hue or stronger chroma than the surrounding material, and which change irreversibly to strongly cemented or indurated nodules on exposure to repeated wetting and drying with free access of oxygen; or b. mottles in platy, polygonal or reticulate patterns that are firm to weakly cemented, with a redder hue or stronger chroma than the surrounding material, and which change irreversibly to strongly cemented or indurated mottles on exposure to repeated wetting and drying with free access of oxygen; and 2. less than 40 percent of the volume strongly cemented or indurated nodules and no continuous, fractured or broken sheets; and 3. both: a. 2.5 percent (by mass) or more citrate-dithionite extractable Fe in the fine earth fraction or 10 percent or more in the nodules or mottles; and b. a ratio between acid oxalate (pH 3) extractable Fe and citrate-dithionite extractable Fe of less than 0.101; and 4. a thickness of 15 cm or more.
1 Estimated from data given by Varghese and Byju (1993).
235 34 World reference base for soil resources 2006
Field identification A plinthic horizon shows red nodules or mottles in platy, polygonal, vesicular or reticulate patterns. In a perennially moist soil, many nodules or mottles are not hard but firm or very firm and can be cut with a spade. They do not harden irreversibly as a result of a single cycle of drying and rewetting but repeated wetting and drying will change them irreversibly to hard nodules or a hardpan (ironstone) or irregular aggregates, especially if also exposed to heat from the sun.
Additional characteristics Micromorphological studies may reveal the extent of impregnation of the soil mass by Fe. The plinthic horizon with nodules has developed under redoximorphic conditions caused by temporally stagnating water and shows a stagnic colour pattern. The plinthic horizon with mottles in platy, polygonal or reticulate patterns has developed under oximorphic conditions in the capillary fringe of groundwater. In this case, the plinthic horizon shows a gleyic colour pattern with oximorphic colours and is in many cases underlain by a whitish horizon. In many plinthic horizons, there are no prolonged reducing conditions.
Relationships with some other diagnostic horizons If the plinthic horizon hardens to a continuous sheet (which later may be broken or fractured), it becomes a petroplinthic horizon. If nodules reach 40 percent or more of the volume and harden separately, it becomes a pisoplinthic horizon. If the nodules or mottles that harden on exposure to repeated wetting and drying do not reach 15 percent of the volume, it may be a ferric horizon if it has 5 percent or more nodules or 15 percent or more mottles fulfilling certain additional requirements.
Salic horizon General description The salic horizon (from Latin sal, salt) is a surface or shallow subsurface horizon that contains a secondary enrichment of readily soluble salts, i.e. salts more soluble than
gypsum (CaSO4.2H2O; log Ks = -4.85 at 25 °C).
Diagnostic criteria A salic horizon has:
1. averaged over its depth an electrical conductivity of the saturation extract (ECe) -1 -1 of 15 dS m or more at 25 °C at some time of the year, or an ECe of 8 dS m or
more at 25 °C if the pH (H2O) of the saturation extract is 8.5 or more; and - 2. averaged over its depth a product of thickness (in centimetres) and ECe (in dS m 1) of 450 or more; and 3. a thickness of 15 cm or more.
Field identification Salicornica or halophyte vegetation such as Tamarix and salt-tolerant crops are first indicators. Salt-affected layers are often puffy. Salts precipitate only after evaporation of the soil moisture; if the soil is moist, salt may not be visible. Salts may precipitate at the surface (external Solonchaks) or at depth (internal Solonchaks). A salt crust is part of the salic horizon.
Additional characteristics -1 An ECe of 8 dS m or more at 25 °C if the pH (H2O) of the saturation extract is 8.5 or more is very common in alkaline carbonate soils.
236 Chapter 2 – Diagnostic horizons, properties and materials 35
Sombric horizon General description A sombric horizon (from French sombre, dark) is a dark-coloured subsurface horizon containing illuvial humus that is neither associated with Al nor dispersed by Na.
Diagnostic criteria A sombric horizon: 1. has a lower Munsell colour value or chroma than the overlying horizon; and
2. has a base saturation (by 1 M NH4OAc) less than 50 percent; and 3. shows evidence of humus accumulation, by a higher organic carbon content with respect to the overlying horizon, or through illuvial humus on ped surfaces or in pores visible in thin sections; and 4. does not underlie an albic horizon; and 5. has a thickness of 15 cm or more.
Field identification Dark-coloured subsoils, associated with cool and moist, well-drained soils of high plateaus and mountains in tropical and subtropical regions. They resemble buried horizons but, in contrast to many of these, sombric horizons more or less follow the shape of the surface.
Relationships with some other diagnostic horizons Sombric horizons may form or have been formed in argic, cambic, ferralic or nitic horizons. Umbric horizons, as well as the dark-coloured melanic and fulvic horizons of Andosols, form at the surface and, as such, are different from sombric horizons. Spodic horizons are differentiated from sombric horizons by their much higher CEC of the clay fraction. The humus-illuvial part of natric horizons has a base saturation
(by 1 M NH4OAc) of more than 50 percent, which separates it from the sombric horizon.
Spodic horizon General description The spodic horizon (from Greek spodos, wood ash) is a subsurface horizon that contains illuvial amorphous substances composed of organic matter and Al, or of illuvial Fe. The illuvial materials are characterized by a high pH-dependent charge, a relatively large surface area and high water retention.
Diagnostic criteria A spodic horizon: 1. has a pH (1:1 in water) of less than 5.9 in 85 percent or more of the horizon, unless the soil is cultivated; and 2. has an organic carbon content of 0.5 percent or more or an optical density of the oxalate extract (ODOE) value of 0.25 or more, at least in some part of the horizon; and 3. has one or both of the following: a. an albic horizon directly overlying the spodic horizon and has, directly under the albic horizon, one of the following Munsell colours, when moist (crushed and smoothed sample): i. a hue of 5 YR or redder; or ii. a hue of 7.5 YR with a value of 5 or less and a chroma of 4 or less; or iii. a hue of 10 YR or neutral and a value and a chroma of 2 or less; or iv. a colour of 10 YR 3/1; or
237 36 World reference base for soil resources 2006
b. with or without an albic horizon, one of the colours listed above, or a hue of 7.5 YR, a value of 5 or less and chroma of 5 or 6, both when moist (crushed and smoothed sample), and one or more of the following: i. cementation by organic matter and Al with or without Fe, in 50 percent or more of the volume and a very firm or firmer consistency in the cemented part; or ii. cracked coatings on sand grains covering 10 percent or more of the surface of the horizon; or 1 iii. 0.50 percent or more Alox + ½Feox and a value less than one-half that amount in an overlying mineral horizon; or iv. an ODOE value of 0.25 or more, and a value less than one-half that amount in an overlying mineral horizon; or v. 10 percent or more (by volume) Fe lamellae2 in a layer 25 cm or more thick. c. does not form part of a natric horizon; and d. has a thickness of 2.5 cm or more.
Field identification A spodic horizon normally underlies an albic horizon and has brownish-black to reddish-brown colours. Spodic horizons can also be characterized by the presence of a thin iron pan, when weakly developed by the presence of organic pellets, or by the accumulation of Fe in lamellar form.
Relationships with some other diagnostic horizons Spodic horizons are usually associated with albic horizons, which they underlie; there may be an anthric, hortic, plaggic, terric or umbric horizons at the surface. Spodic horizons may exhibit andic properties owing to the alumino-organic
complexes. Spodic horizons have at least twice as much the Alox + ½Feox percentages as overlying layers, such as an albic, anthric, hortic, plaggic, terric or umbric horizon. This criterion does not normally apply to non-spodic layers with andic properties in which the alumino-organic complexes are hardly mobile. Similar to many spodic horizons, sombric horizons also contain more organic matter than an overlying layer. They can be differentiated from each other by the clay mineralogy (kaolinite usually dominating in sombric horizons, whereas the clay fraction of spodic horizons commonly contains significant amounts of vermiculite and Al-interlayered chlorite) and the much higher CEC of the clay fraction in spodic horizons. Similarly, plinthic horizons, which contain large amounts of illuvial Fe, are dominated by kaolinitic clay minerals and, therefore, have a much lower CEC of the clay fraction than that of spodic horizons.
Takyric horizon General description A takyric horizon (from Turkic languages takyr, barren land) is a heavy-textured surface horizon comprising a surface crust and a platy structured lower part. It occurs under arid conditions in periodically flooded soils.
Diagnostic criteria A takyric horizon has: 1. aridic properties; and
1 Alox and Feox: acid oxalate-extractable aluminium and iron, respectively (Blakemore, Searle and Daly, 1981), expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105 °C) basis. 2 Iron lamellae are non-cemented bands of illuvial iron less than 2.5 cm thick. 238 Chapter 2 – Diagnostic horizons, properties and materials 37
2. a platy or massive structure; and 3. a surface crust that has all of the following: a. thickness enough that it does not curl entirely upon drying; and b. polygonal cracks extending 2 cm or more deep when the soil is dry; and c. sandy clay loam, clay loam, silty clay loam or finer texture; and d. very hard consistence when dry, and very plastic and sticky consistence when wet; and -1 e. an electrical conductivity (ECe) of the saturated extract of less than 4 dS m , or less than that of the layer immediately below the takyric horizon.
Field identification Takyric horizons occur in depressions in arid regions, where surface water, rich in clay and silt but relatively low in soluble salts, accumulates and leaches the upper soil horizons. Periodic leaching of salt disperses clay and forms a thick, compact, fine- textured crust with prominent polygonal cracks when dry. The crust often contains more than 80 percent clay and silt.
Relationships with some other diagnostic horizons Takyric horizons occur in association with many diagnostic horizons, the most important ones being the salic, gypsic, calcic and cambic horizons. The low EC and low soluble-salt content of takyric horizons set them apart from the salic horizon.
Terric horizon General description A terric horizon (from Latin terra, earth) is a human-induced mineral surface horizon that develops through addition of earthy manures, compost, beach sands or mud over a long period of time. It builds up gradually and may contain stones, randomly sorted and distributed.
Diagnostic criteria A terric horizon is a mineral surface horizon and: 1. has a colour related to the source material; and 2. contains less than 20 percent artefacts (by volume); and
3. has a base saturation (by 1 M NH4OAc) of 50 percent or more; and 4. occurs in locally raised land surfaces; and 5. does not show stratification but has an irregular textural differentiation; and 6. has a lithological discontinuity at its base; and 7. has a thickness of 20 cm or more.
Field identification Soils with a terric horizon show a raised surface that may be inferred either from field observation or from historical records. The terric horizon is not homogeneous, but subhorizons are thoroughly mixed. It commonly contains artefacts such as pottery fragments, cultural debris and refuse, which are typically very small (less than 1 cm in diameter) and much abraded.
Relationships with some other diagnostic horizons Few soil characteristics differentiate the terric and plaggic horizons from each other. Terric horizons commonly show a high biological activity, have a neutral to slightly alkaline soil reaction (pH [H2O] is normally more than 7.0), and may contain free lime, whereas plaggic horizons have an acid soil reaction. The colour of the terric horizon is strongly related to the source material. Buried soils may be observed at the base of the horizon although mixing can obscure the contact. 239 38 World reference base for soil resources 2006
Thionic horizon General description The thionic horizon (from Greek theion, sulphur) is an extremely acid subsurface horizon in which sulphuric acid is formed through oxidation of sulphides.
Diagnostic criteria A thionic horizon has: 1. a pH (1:1 in water) of less than 4.0; and 2. one or more of the following: a. yellow jarosite or yellowish-brown schwertmannite mottles or coatings; or b. concentrations with a Munsell hue of 2.5 Y or yellower and a chroma of 6 or more, moist; or c. direct superposition on sulphidic material; or d. 0.05 percent (by mass) or more water-soluble sulphate; and 2. a thickness of 15 cm or more.
Field identification Thionic horizons generally exhibit pale yellow jarosite or yellowish-brown
schwertmannite mottles or coatings. Soil reaction is extremely acid; pH (H2O) of 3.5 is not uncommon. While mostly associated with recent sulphidic coastal sediments, thionic horizons also develop inland in sulphidic materials exposed by excavation or erosion.
Relationships with some other diagnostic horizons The thionic horizon often underlies a strongly mottled horizon with pronounced redoximorphic features (reddish to reddish-brown iron hydroxide mottles and a light- coloured, Fe-depleted matrix).
Umbric horizon General characteristics The umbric horizon (from Latin umbra, shade) is a thick, dark-coloured, base-depleted surface horizon rich in organic matter.
Diagnostic criteria An umbric horizon, after mixing either the upper 20 cm of the mineral soil or, if continuous rock, a cryic, petroduric or petroplinthic horizon is present within 20 cm of the mineral soil surface, the entire mineral soil above, has: 1. a soil structure sufficiently strong that the horizon is not both massive and hard or very hard when dry in both the mixed part and the underlying unmixed part, if the minimum thickness is larger than 20 cm (prisms larger than 30 cm in diameter are included in the meaning of massive if there is no secondary structure within the prisms); and 2. Munsell colours with a chroma of 3 or less when moist, a value of 3 or less when moist and 5 or less when dry, both on broken samples in both the mixed part and the underlying unmixed part, if the minimum thickness is greater than 20 cm. The colour value is one unit or more darker than that of the parent material unless the parent material has a colour value of 4 or less, moist, in which case the colour contrast requirement is waived. If a parent material is absent, comparison must be made with the layer immediately underlying the surface layer; and 3. an organic carbon content of 0.6 percent or more, in both the mixed part and the underlying unmixed part, if the minimum thickness is larger than 20 cm. The organic carbon content is at least 0.6 percent more than in the parent material if 240 Chapter 2 – Diagnostic horizons, properties and materials 39
the colour requirements are waived because of dark coloured parent materials; and
4. a base saturation (by 1 M NH4OAc) of less than 50 percent on a weighted average throughout the depth of the horizon; and 5. a thickness of one of the following: a. 10 cm or more if directly overlying continuous rock, a cryic, petroplinthic or petroduric horizon; or b. 20 cm or more and one-third or more of the thickness between the soil surface and the upper boundary of continuous rock, or a cryic, gypsic, petroduric, petrogypsic, petroplinthic or salic horizon or calcaric, fluvic or gypsyric material within 75 cm; or c. 20 cm or more and one-third or more of the thickness between the soil surface and the lower boundary of the lowest diagnostic horizon within 75 cm and, if present, above any of the diagnostic horizons listed under b.; or d. 25 cm or more.
Field identification The main field characteristics of an umbric horizon are its dark colour and its structure. In general, umbric horizons tend to have a lesser grade of soil structure than mollic horizons.
Most umbric horizons have an acid reaction (pH [H2O, 1:2.5] of less than about 5.5), which represents a base saturation of less than 50 percent. An additional indication for the acidity is a shallow, horizontal rooting pattern in the absence of a physical barrier.
Relationships with some other diagnostic horizons The base saturation requirement sets the umbric horizon apart from the mollic horizon, which is otherwise very similar. The upper limit of organic carbon content varies from 12 percent (20 percent organic matter) to 18 percent (30 percent organic matter), which is the lower limit for the histic horizon, or 20 percent, the lower limit of a folic horizon. Some thick, dark-coloured, organic-rich, base-desaturated surface horizons occur, which are formed as a result of human activities, such as deep cultivation and manuring, the addition of organic manures, the presence of ancient settlements, and kitchen middens (anthragric, hortic, plaggic or terric horizons). These horizons can usually be recognized in the field by the presence of artefacts, spade marks, contrasting mineral inclusions or stratification indicating the intermittent addition of manurial material, a relative higher position in the landscape, or by checking the agricultural history of the area.
Vertic horizon General description The vertic horizon (from Latin vertere, to turn) is a clayey subsurface horizon that, as a result of shrinking and swelling, has slickensides and wedge-shaped structural aggregates.
Diagnostic criteria A vertic horizon: 1. contains 30 percent or more clay throughout; and 2. has wedge-shaped structural aggregates with a longitudinal axis tilted between 10 ° and 60 ° from the horizontal; and 3. has slickensides1; and
1 Slickensides are polished and grooved ped surfaces that are produced by aggregates sliding one past another. 241 40 World reference base for soil resources 2006
4. has a thickness of 25 cm or more.
Field identification Vertic horizons are clayey, with a hard to very hard consistency. When dry, vertic horizons show cracks of 1 cm or more wide. Polished, shiny ped surfaces (slickensides), often at sharp angles, are distinctive.
Additional characteristics The COLE is a measure for the shrink–swell potential and is defined as the ratio of the difference between the moist length and the dry length of a clod to its dry length:
(Lm - Ld)/Ld, in which Lm is the length at 33 kPa tension and Ld the length when dry. In vertic horizons, the COLE is more than 0.06.
Relationships with some other diagnostic horizons Several other diagnostic horizons may also have high clay content, viz. the argic, natric and nitic horizons. These horizons lack the characteristic typical for the vertic horizon; however, they may be laterally linked in the landscape with the vertic horizon usually taking up the lowest position.
Voronic horizon General description The voronic horizon (from Russian voronoj, black) is a special type of mollic horizon. It is a deep, well-structured, blackish surface horizon with a high base saturation, a high content of organic matter and a high biological activity.
Diagnostic criteria A voronic horizon is a mineral surface horizon and has: 1. granular or fine subangular blocky soil structure; and 2. Munsell colours with a chroma of less than 2.0 when moist, a value less than 2.0 when moist and 3.0 when dry on broken samples. If there is 40 percent or more finely divided lime, or if the texture of the horizon is loamy sand or coarser, the limits of colour value when dry are waived; the colour value when moist is 3.0 or less. The colour value is one unit or more darker than that of the parent material (both moist and dry), unless the parent material has a colour value less than 4.0, moist. If a parent material is not present, comparison must be made with the layer immediately underlying the surface layer. The above colour requirements apply to the upper 15 cm of the voronic horizon, or immediately below any plough layer; and 3. 50 percent or more (by volume) of the horizon consisting of worm burrows, worm casts, and filled burrows; and 4. an organic carbon content of 1.5 percent or more. The organic carbon content is 6 percent or more if the colour requirements are waived because of finely divided lime, or 1.5 percent more than in the parent material if the colour requirements are waived because of dark coloured parent materials; and
5. a base saturation (by 1 M NH4OAc) of 80 percent or more; and 6. a thickness of 35 cm or more.
Field identification The voronic horizon is identified by its blackish colour, well-developed structure (usually granular), high activity of worms and other burrowing animals, and its thickness.
242 Chapter 2 – Diagnostic horizons, properties and materials 41
Relationships with some other diagnostic horizons Its higher organic carbon content, the darker colours required, the high biological contribution to the soil structure, and its greater minimum depth express the special character of the voronic horizon with respect to the mollic horizon.
Yermic horizon General description The yermic horizon (from Spanish yermo, desert) is a surface horizon that usually, but not always, consists of surface accumulations of rock fragments (desert pavement) embedded in a loamy vesicular layer that may be covered by a thin aeolian sand or loess layer.
Diagnostic criteria A yermic horizon has: 1. aridic properties; and 2. one or more of the following: a. a pavement that is varnished or includes wind-shaped gravel or stones (ventifacts); or b. a pavement associated with a vesicular layer; or c. a vesicular layer below a platy surface layer.
Field identification A yermic horizon comprises a pavement and/or a vesicular layer that has a loamy texture. The vesicular layer shows a polygonal network of desiccation cracks, often filled with in-blown material, that extend into the underlying layers. The surface layers have a weak to moderate platy structure.
Relationships with some other diagnostic horizons Yermic horizons often occur in association with other diagnostic horizons characteristic for desert environments (salic, gypsic, duric, calcic and cambic horizons). In very cold deserts (e.g. Antarctica), they may occur associated with cryic horizons. Under these conditions, coarse cryoclastic material dominates and there is little dust to be deflated and deposited by wind. Here, a dense pavement with varnish, ventifacts, aeolian sand layers and soluble mineral accumulations may occur directly on loose deposits, without a vesicular layer.
DIAGNOSTIC PROPERTIES
Abrupt textural change General description An abrupt textural change (from Latin abruptus) is a very sharp increase in clay content within a limited depth range.
Diagnostic criteria An abrupt textural change requires 8 percent or more clay in the underlying layer and: 1. doubling of the clay content within 7.5 cm if the overlying layer has less than 20 percent clay; or 2. 20 percent (absolute) increase in clay content within 7.5 cm if the overlying layer has 20 percent or more clay.
Albeluvic tonguing General description The term albeluvic tonguing (from Latin albus, white, and eluere, to wash out) is connotative of penetrations of clay- and Fe-depleted material into an argic horizon. 243 42 World reference base for soil resources 2006
When peds are present, albeluvic tongues occur along ped surfaces.
Diagnostic criteria Albeluvic tongues: 1. have the colour of an albic horizon; and 2. have greater depth than width, with the following horizontal dimensions: a. 5 mm or more in clayey argic horizons; or b. 10 mm or more in clay loam and silty argic horizons; or c. 15 mm or more in coarser (silt loam, loam or sandy loam) argic horizons; and 3. occupy 10 percent or more of the volume in the first 10 cm of the argic horizon, measured on both vertical and horizontal sections; and 4. have a particle-size distribution matching that of the coarser textured horizon overlying the argic horizon.
Andic properties General description Andic properties (from Japanese an, dark, and do, soil) result from moderate weathering of mainly pyroclastic deposits. However, some soils develop andic properties from non- volcanic materials (e.g. loess, argillite and ferralitic weathering products). The presence of short-range-order minerals and/or organo-metallic complexes is characteristic for andic properties. These minerals and complexes are commonly part of the weathering sequence in pyroclastic deposits (tephric soil material à vitric properties à andic properties). Andic properties may be found at the soil surface or in the subsurface, commonly occurring as layers. Many surface layers with andic properties contain a high amount of organic matter (more than 5 percent), are commonly very dark coloured (Munsell value and chroma, moist, are 3 or less), have a fluffy macrostructure and, in some places, a smeary consistence. They have a low bulk density and commonly have a silt loam or finer texture. Andic surface layers rich in organic matter may be very thick, having a thickness of 50 cm or more (pachic characteristic) in some soils. Andic subsurface layers are generally somewhat lighter coloured. Andic layers may have different characteristics, depending on the type of the dominant weathering process acting upon the soil material. They may exhibit thixotropy, i.e. the soil material changes, under pressure or by rubbing, from a plastic solid into a liquefied stage and back into the solid condition. In perhumid climates, humus-rich andic layers may contain more than twice the water content of samples that have been oven-dried and rewetted (hydric characteristic). Two major types of andic properties are recognized: one in which allophane and similar minerals are predominant (the sil-andic type); and one in which Al complexed by organic acids prevails (the alu-andic type). The sil-andic property typically gives a strongly acid to neutral soil reaction, while the alu-andic property gives an extremely acid to acid reaction.
Diagnostic criteria Andic properties1 require: 2 1. an Alox + ½Feox value of 2.0 percent or more; and 2. a bulk density3 of 0.90 kg dm-3 or less; and 3. a phosphate retention of 85 percent or more; and
1 Shoji et al., 1996; Takahashi, Nanzyo and Shoji, 2004. 2 Alox and Feox are acid oxalate-extractable aluminium and iron, respectively (Blakemore, Searle and Daly, 1981), expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105 °C) basis. 3 For bulk density, the volume is determined after an undried soil sample has been desorbed at 33 kPa (no prior drying) and afterwards weighed oven-dried (see Annex 1). 244 Chapter 2 – Diagnostic horizons, properties and materials 43
4. if occurring under tephric material that meets the requirements of an albic 1 4 horizon, a Cpy/OC or a Cf/Cpy of less than 0.5; and 5. less than 25 percent (by mass) organic carbon. Andic properties may be divided into sil-andic and alu-andic properties. Sil-andic properties show an acid-oxalate (pH 3) extractable silica (Siox) content of 0.6 percent or 2 more or an Alpy /Alox of less than 0.5; alu-andic properties show a Siox content of less than 0.6 percent and an Alpy/Alox of 0.5 or more. Transitional alu-sil-andic properties that show a Siox content between 0.6 and 0.9 percent and an Alpy/Alox between 0.3 and 0.5 may occur (Poulenard and Herbillon, 2000).
Field identification Andic properties may be identified using the sodium fluoride field test of Fieldes and Perrott (1966). A pH in NaF of more than 9.5 indicates allophane and/or organo- aluminium complexes. The test is indicative for most layers with andic properties, except for those very rich in organic matter. However, the same reaction occurs in spodic horizons and in certain acid clays that are rich in Al-interlayered clay minerals. Uncultivated, organic matter-rich surface layers with sil-andic properties typically have a pH (H2O) of 4.5 or higher, while uncultivated surface layers with alu-andic properties and rich in organic matter typically have a pH (H2O) of less than 4.5.
Generally, pH (H2O) in sil-andic subsoil layers is more than 5.0.
Relationships with some diagnostic horizons and properties Vitric properties are distinguished from andic properties by a lesser degree of weathering. This is evidenced by a lower amount of non-crystalline or paracrystalline pedogenetic minerals, as characterized by the moderate amount of acid oxalate (pH 3) extractable Al and Fe in layers with vitric properties (Alox + ½Feox = 0.4–2.0 percent), by a higher bulk density (BD > 0.9 kg dm-3), or by a lower phosphate retention (25 – <85 percent). Histic or folic horizons with less than 25 percent organic carbon may have andic properties. In organic layers with 25 percent or more organic carbon, andic properties are not considered. Spodic horizons, which also contain complexes of sesquioxides and organic substances, can have similar characteristics to those of layers with andic properties rich in alumino-organic complexes. Many spodic horizons have at least twice as much Alox + ½Feox as an overlying layer. This normally does not apply to layers with andic properties in which the alumino-organic complexes are virtually immobile. However, particularly in Podzols to which the Entic qualifier applies and which have a spodic horizon without the requirement of at least twice as much Alox + ½Feox as an overlying layer, other diagnostic criteria such as the bulk density are needed in order to discriminate between layers with andic properties and spodic horizons. Some layers with andic properties are covered by relatively young, light-coloured volcanic ejecta that are difficult to distinguish from an albic horizon. Therefore, in a number of cases, analytical tests are needed in order to verify the difference between layers with andic properties and spodic horizons, in particular the Cpy to OC or Cf to
Cpy ratio tests.
Aridic properties General description The term aridic properties (from Latin aridus, dry) combines a number of properties that are common in surface horizons of soils occurring under arid conditions and
1 Cpy, Cf and OC are pyrophosphate-extractable C, fulvic acid C and organic C, respectively (Ito et al., 1991), expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105 °C) basis. 2 Alpy: pyrophosphate-extractable aluminium, expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105 °C) basis. 245 44 World reference base for soil resources 2006
where pedogenesis exceeds new accumulation at the soil surface by aeolian or alluvial activity.
Diagnostic criteria Aridic properties require all of the following: 1. an organic carbon content of less than 0.6 percent1 if the texture is sandy loam or finer, or less than 0.2 percent if the texture is coarser than sandy loam, as a weighted average in the upper 20 cm of the soil or down to the top of a diagnostic subsurface horizon, a cemented layer, or to continuous rock, whichever is shallower; and 2. evidence of aeolian activity in one or more of the following forms: a. the sand fraction in some layer or in in-blown material filling cracks contains rounded or subangular sand particles showing a matt surface (use a ×10 hand- lens). These particles make up 10 percent or more of the medium and coarser quartz sand fraction; or b. wind-shaped rock fragments (ventifacts) at the surface; or c. aeroturbation (e.g. cross-bedding); or d. evidence of wind erosion or deposition; and 3. both broken and crushed samples with a Munsell colour value of 3 or more when moist and 4.5 or more when dry, and a chroma of 2 or more when moist; and
4. base saturation (by 1 M NH4OAc) of 75 percent or more.
Additional remarks The presence of acicular (needle-shaped) clay minerals (e.g. sepiolite and palygorskite) in soils is considered connotative of a desert environment, but it has not been reported in all desert soils. This may be due either to the fact that, under arid conditions, acicular clays are not produced but only preserved, provided they exist in the parent material or in the dust that falls on the soil, or that, in some desert environments, there has not been sufficient weathering to produce detectable quantities of secondary clay minerals.
Continuous rock Definition Continuous rock is consolidated material underlying the soil, exclusive of cemented pedogenetic horizons such as petrocalcic, petroduric, petrogypsic and petroplinthic horizons. Continuous rock is sufficiently consolidated to remain intact when an air- dried specimen 25–30 mm on a side is submerged in water for 1 hour. The material is considered continuous only if cracks into which roots can enter are on average 10 cm or more apart and occupy less than 20 percent (by volume) of the continuous rock, with no significant displacement of the rock having taken place.
Ferralic properties General description Ferralic properties (from Latin ferrum, iron, and alumen, alum) refer to mineral soil material that has a relatively low CEC. It also includes soil materials that fulfil the requirements of a ferralic horizon except texture.
Diagnostic criteria Ferralic properties require in some subsurface layer: -1 2 1. a CEC (by 1 M NH4OAc) of less than 24 cmolc kg clay ; or
1 -1 The organic carbon content may be higher if the soil is periodically flooded, or if it has an ECe of 4 dS m or more somewhere within 100 cm of the soil surface. 2 See Annex 1. 246 Chapter 2 – Diagnostic horizons, properties and materials 45
-1 2. a CEC (by 1 M NH4OAc) of less than 4 cmolc kg soil and a Munsell chroma of 5 or more, moist.
Geric properties General description Geric properties (from Greek geraios, old) refer to mineral soil material that has a very low ECEC or even acts as an anion exchanger.
Diagnostic criteria Geric properties require: 1. an ECEC (sum of exchangeable bases plus exchangeable acidity in 1 M KCl) of -1 1 less than 1.5 cmolc kg clay ; or
2. a delta pH (pHKCl minus pHwater) of +0.1 or more.
Gleyic colour pattern General description Soil materials develop a gleyic colour pattern (from Russian gley, mucky soil mass) if they are saturated with groundwater, unless drained, for a period that allows reducing conditions to occur (this may range from a few days in the tropics to a few weeks in other areas), and show a gleyic colour pattern.
Diagnostic criteria A gleyic colour pattern shows one or both of the following: 1. 90 percent or more reductimorphic colours, which comprise neutral white to black (Munsell N1/ to N8/) or bluish to greenish (Munsell 2.5 Y, 5 Y, 5 G, 5 B); or 2. 5 percent or more mottles of oximorphic colours, which comprise any colour, excluding reductimorphic colours.
Field identification A gleyic colour pattern results from a redox gradient between groundwater and capillary fringe causing an uneven distribution of iron and manganese (hydr)oxides. In the lower part of the soil and/or inside the peds, the oxides are either transformed into insoluble Fe/Mn(II) compounds or they are translocated; both processes lead to the absence of colours with a hue redder than 2.5 Y. Translocated Fe and Mn compounds can be concentrated in the oxidized form (Fe[III], Mn[IV]) on ped surfaces or in biopores (rusty root channels), and towards the surface even in the matrix. Manganese concentrations can be recognized by strong effervescence using a 10-percent H2O2 solution. Reductimorphic colours reflect permanently wet conditions. In loamy and clayey material, blue-green colours dominate owing to Fe (II, III) hydroxy salts (green rust). If the material is rich in sulphur (S), blackish colours prevail owing to colloidal iron sulphides such as greigite or mackinawite (easily recognized by smell after applying 1 M HCl). In calcareous material, whitish colours are dominant owing to calcite and/or siderite. Sands are usually light grey to white in colour and often also impoverished in Fe and Mn. Bluish-green and black colours are unstable and often oxidize to a reddish brown within a few hours of exposure to air. The upper part of a reductimorphic layer may show up to 10 percent rusty colours, mainly around channels of burrowing animals or plant roots. Oximorphic colours reflect alternating reducing and oxidizing conditions, as is the case in the capillary fringe and in the surface horizons of soils with fluctuating
1 See Annex 1. 247 46 World reference base for soil resources 2006
groundwater levels. Specific colours indicate ferrihydrite (reddish brown), goethite (bright yellowish brown), lepidocrocite (orange), and jarosite (pale yellow). In loamy and clayey soils, the iron oxides/hydroxides are concentrated on aggregate surfaces and the walls of larger pores (e.g. old root channels).
Additional characteristics If a layer has a gleyic colour pattern in 50 percent of its volume, the layer has in the other 50 percent a matrix of oximorphic colours, i.e. neither reductimorphic colours nor mottles of oximorphic colours.
Lithological discontinuity General description Lithological discontinuities (from Greek lithos, stone, and Latin continuare, to continue) are significant changes in particle-size distribution or mineralogy that represent differences in lithology within a soil. A lithological discontinuity can also denote an age difference.
Diagnostic criteria A lithological discontinuity requires one or more of the following: 1. an abrupt change in particle-size distribution that is not solely associated with a change in clay content resulting from pedogenesis; or 2. a relative change of 20 percent or more in the ratios between coarse sand, medium sand, and fine sand; or 3. rock fragments that do not have the same lithology as the underlying continuous rock; or 4. a layer containing rock fragments without weathering rinds overlying a layer containing rocks with weathering rinds; or 5. layers with angular rock fragments overlying or underlying layers with rounded rock fragments; or 6. abrupt changes in colour not resulting from pedogenesis; or 7. marked differences in size and shape of resistant minerals between superimposed layers (as shown by micromorphological or mineralogical methods).
Additional characteristics In cases, a horizontal line of rock fragments (stone line) overlying and underlying layers with smaller amounts or rock fragments or a decreasing percentage of rock fragments with increasing depth may also be suggestive of a lithological discontinuity, although the sorting action of small fauna such as termites can produce similar effects in what would initially have been lithologically uniform parent material.
Reducing conditions Definition Reducing conditions (from Latin reducere) show one or more of the following: 1. a negative logarithm of the hydrogen partial pressure (rH) of less than 20; or 2. the presence of free Fe2+, as shown on a freshly broken and smoothed surface of a field-wet soil by the appearance of a strong red colour after wetting it with a 0.2-percent a,a, dipyridyl solution in 10-percent acetic acid1; or 3. the presence of iron sulphide; or 4. the presence of methane.
1 This test may not give the strong red colour in soil materials with a neutral or alkaline soil reaction. 248 Chapter 2 – Diagnostic horizons, properties and materials 47
Secondary carbonates General description The term secondary carbonates (from Latin carbo, coal) refers to translocated lime, precipitated in place from the soil solution rather than inherited from a soil parent material. As a diagnostic property, it should be present in significant quantities.
Field identification Secondary carbonates either may disrupt the soil structure or fabric, forming masses, nodules, concretions or spheroidal aggregates (white eyes) that are soft and powdery when dry, or may be present as soft coatings in pores, on structural faces or on the undersides of rock or cemented fragments. If present as coatings, secondary carbonates cover 50 percent or more of the structural faces and are thick enough to be visible when moist. If present as soft nodules, they occupy 5 percent or more of the soil volume. Filaments (pseudomycelia) are only included in the definition of secondary carbonates if they are permanent and do not come and go with changing moisture conditions. This can be checked by spraying some water.
Stagnic colour pattern General description Soil material has a stagnic colour pattern (from Latin stagnare, to stagnate) if it is, at least temporarily, saturated with surface water, unless drained, for a period long enough to allow reducing conditions to occur (this may range from a few days in the tropics to a few weeks in other areas).
Diagnostic criteria A stagnic colour pattern shows mottling in such a way that the surfaces of the peds (or parts of the soil matrix) are lighter (at least one Munsell value unit more) and paler (at least one chroma unit less), and the interiors of the peds (or parts of the soil matrix) are more reddish (at least one hue unit) and brighter (at least one chroma unit more) than the non-redoximorphic parts of the layer, or than the mixed average of the interior and surface parts.
Additional characteristics If a layer has a stagnic colour pattern in 50 percent of its volume the other 50 percent of the layer are neither lighter and paler nor more reddish and brighter.
Vertic properties Diagnostic criteria Soil material with vertic properties (from Latin vertere, to turn) has one or both of the following: 1. 30 percent or more clay throughout a thickness of 15 cm or more and one or both of the following: a. slickensides or wedge-shaped aggregates; or b. cracks that open and close periodically and are 1 cm or more wide; or 2. a COLE of 0.06 or more averaged over depth of 100 cm from the soil surface.
Vitric properties General description Vitric properties (from Latin vitrum, glass) apply to layers with volcanic glass and other primary minerals derived from volcanic ejecta and which contain a limited amount of short-range-order minerals.
249 48 World reference base for soil resources 2006
Diagnostic criteria Vitric properties1 require: 1. 5 percent or more (by grain count) volcanic glass, glassy aggregates and other glass-coated primary minerals, in the fraction between 0.05 and 2 mm, or in the fraction between 0.02 and 0.25 mm; and 2 2. an Alox + ½Feox value of 0.4 percent or more; and 3. a phosphate retention of 25 percent or more; and 4. if occurring under tephric material that meets the requirements of an albic 3 4 horizon, a Cpy/OC or a Cf/Cpy of less than 0.5; and 5. less than 25 percent (by mass) organic carbon.
Field identification Vitric properties can occur in a surface layer. However, they can also occur under some tens of centimetres of recent pyroclastic deposits. Layers with vitric properties can have an appreciable amount of organic matter. The sand and coarse silt fractions of layers with vitric properties have a significant amount of unaltered or partially altered volcanic glass, glassy aggregates and other glass-coated primary minerals (coarser fractions may be checked by ×10 hand-lens; finer fractions may be checked by microscope).
Relationships with some diagnostic horizons, properties and materials Vitric properties are, on the one hand, closely linked with andic properties, into which they may eventually develop. On the other hand, layers with vitric properties develop from tephric materials. Mollic and umbric horizons may exhibit vitric properties as well.
DIAGNOSTIC MATERIALS
Artefacts Definition Artefacts (from Latin ars, art, and facere, to make) are solid or liquid substances that are: 1. one or both of the following: a created or substantially modified by humans as part of an industrial or artisanal manufacturing process; or b. brought to the surface by human activity from a depth where they were not influenced by surface processes, with properties substantially different from the environment where they are placed; and 2. have substantially the same properties as when first manufactured, modified or excavated. Examples of artefacts are bricks, pottery, glass, crushed or dressed stone, industrial waste, garbage, processed oil products, mine spoil and crude oil.
Calcaric material Definition Calcaric material (from Latin calcarius) effervescences strongly with 1 M HCl in most of the fine earth. It applies to material that contains 2 percent or more calcium carbonate equivalent.
1 Adapted after Takahashi, Nanzyo and Shoji (2004) and findings of the COST 622 Action. 2 Alox and Feox are acid oxalate-extractable aluminium and iron, respectively (Blakemore, Searle and Daly, 1987), expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105 °C) basis. 3 Cpy, Cf and OC are pyrophosphate-extractable C, fulvic acid C and organic C, respectively (Ito et al., 1991), expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105 °C) basis. 250 Chapter 2 – Diagnostic horizons, properties and materials 49
Colluvic material General description Colluvic (from Latin colluere, to wash) material is formed by sedimentation through human-induced erosion. It normally accumulates in foot slope positions, in depressions or above hedge walls. The erosion may have taken place since Neolithic times.
Field identification The upper part of the colluvic material shows characteristics (texture, colour, pH and organic carbon content) similar to the surface layer of the source in the neighbourhood. Many colluvic materials have artefacts such as pieces of bricks, ceramics and glass. Stratification is common although not always easily detectable, and many colluvic materials have a lithological discontinuity at their base.
Fluvic material General description Fluvic material (from Latin fluvius, river) refers to fluviatile, marine and lacustrine sediments that receive fresh material at regular intervals or have received it in the recent past1.
Diagnostic criteria Fluvic material is of fluviatile, marine or lacustrine origin that shows stratification in at least 25 percent of the soil volume over a specified depth; stratification may also be evident from an organic carbon content decreasing irregularly with depth, or remaining above 0.2 percent to a depth of 100 cm from the mineral soil surface. Thin strata of sand may have less organic carbon if the finer sediments below meet the latter requirement.
Field identification Stratification, taking such forms as alternating darker coloured soil layers, reflects an irregular decrease in organic carbon content with depth. Fluvic material is always associated with organized water bodies and should be distinguished from colluvial deposits (sheet colluvia, splays and colluvial cones), even though they look very much the same.
Gypsiric material Definition Gypsiric material (from Greek gypsos) is mineral material that contains 5 percent or more gypsum (by volume).
Limnic material Diagnostic criteria Limnic material (from Greek limnae, pool) includes both organic and mineral materials that are: 1. deposited in water by precipitation or through action of aquatic organisms, such as diatoms and other algae; or 2. derived from underwater and floating aquatic plants and subsequently modified by aquatic animals.
Field identification Limnic material occurs as subaquatic deposits (or at the surface after drainage). Four types of limnic material are distinguished:
1 Recent past covers the period during which the soil has been protected from flooding, e.g. by empoldering, embanking, canalization or artificial drainage, and during which time soil formation has not resulted in the development of any diagnostic subsurface horizon apart from a salic or sulphuric horizon. 251 50 World reference base for soil resources 2006
1. Coprogenous earth or sedimentary peat: dominantly organic, identifiable through many faecal pellets, Munsell colour value (moist) 4 or less, slightly viscous water suspension, non- or slightly plastic and non-sticky consistence, shrinking upon drying, difficult to rewet after drying, and cracking along horizontal planes. 2. Diatomaceous earth: mainly diatoms (siliceous), identifiable by irreversible changing of the matrix colour (Munsell value 3, 4 or 5 in field moist or wet condition) as a result of the irreversibly shrinkage of the organic coatings on diatoms (use 440× microscope). 3. Marl: strongly calcareous, identifiable by a Munsell colour value, moist, of 5 or more, and a reaction with 10-percent HCl. The colour of marl does not usually change upon drying. 4. Gyttja: small coprogenic aggregates of strongly humified organic matter and minerals of predominantly clay to silt size, 0.5 percent or more organic carbon, a Munsell colour hue of 5 Y, GY or G, strong shrinkage after drainage and an rH value of 13 or more.
Mineral material General description In mineral material (from Celtic mine, mineral), the soil properties are dominated by mineral components.
Diagnostic criteria Mineral material has one or both of the following: 1. less than 20 percent organic carbon in the fine earth (by mass) if saturated with water for less than 30 consecutive days in most years without being drained; or 2. one or both of the following: a. less than (12 + [clay percentage of the mineral fraction × 0.1]) percent organic carbon in the fine earth (by mass), or b. less than 18 percent organic carbon in the fine earth (by mass), if the mineral fraction has 60 percent or more clay.
Organic material General description Organic material (from Greek organon, tool) consists of a large amount of organic debris that accumulates at the surface under either wet or dry conditions and in which the mineral component does not significantly influence the soil properties.
Diagnostic criteria Organic material has one or both of the following: 1. 20 percent or more organic carbon in the fine earth (by mass); or 2. if saturated with water for 30 consecutive days or more in most years (unless drained), one or both of the following: a. (12 + [clay percentage of the mineral fraction × 0.1]) percent or more organic carbon in the fine earth (by mass), or b. 18 percent or more organic carbon in the fine earth (by mass).
Ornithogenic material General description Ornithogenic material (from Greek ornithos, bird, and genesis, origin) is material with strong influence of bird excrement. It often has a high content of gravel that has been transported by birds. 252 Chapter 2 – Diagnostic horizons, properties and materials 51
Diagnostic criteria Ornithogenic material has: 1. remnants of birds or bird activity (bones, feathers, and sorted gravel of similar size); and
2. a P2O5 content of 0.25 percent or more in 1-percent citric acid.
Sulphidic material General description Sulphidic material (from English sulphide) is a waterlogged deposit containing S, mostly in the form of sulphides, and only moderate amounts of calcium carbonate.
Diagnostic criteria Sulphidic material has: 1. 0.75 percent or more S (dry mass) and less than three times as much calcium carbonate equivalent as S; and 2. pH (1:1 in water) of 4.0 or more.
Field identification In moist or wet conditions, deposits containing sulphides often show a golden shine, the colour of pyrite. Forced oxidation with a 30-percent hydrogen peroxide solution lowers the pH to 2.5 or less, the reaction may be vigorous in sunlight or on heating. Munsell colours range: hues of N, 5 Y, 5 GY, 5 BG, or 5 G; values of 2, 3 or 4; chroma always 1. The colour is usually unstable, and blackens upon exposure. Sulphidic clay is usually practically unripe. If the soil is disturbed, a whiff of rotten eggs may be noticed. This is accentuated by application of 1 M HCl.
Technic hard rock Definition Technic hard rock (from Greek technikos, skilfully made or constructed) is consolidated material resulting from an industrial process, with properties substantially different from those of natural materials.
Tephric material General description Tephric material1 (from Greek tephra, pile ash) consists either of tephra, i.e. unconsolidated, non- or only slightly weathered primary pyroclastic products of volcanic eruptions (including ash, cinders, lapilli, pumice, pumice-like vesicular pyroclastics, blocks and volcanic bombs), or of tephric deposits, i.e. tephra that has been reworked and mixed with material from other sources. This includes tephric loess, tephric blown sand and volcanogenic alluvium.
Diagnostic criteria Tephric material has: 1. 30 percent or more (by grain count) volcanic glass, glass-coated primary minerals, glassy materials, and glassy aggregates in the 0.02–2 mm particle-size fraction; and 2. no andic or vitric properties.
Relationships with some diagnostic horizons The low amount of acid oxalate extractable Al and Fe sets tephric material apart from layers with vitric or andic properties.
1 Description and diagnostic criteria are adapted from Hewitt (1992). 253 254 53
Chapter 3 Key to the reference soil groups of the WRB with lists of prefix and suffix qualifiers
Key to the reference soil groups Prefix qualifiers Suffix qualifiers Soils having organic material, either Folic Thionic 1. 10 cm or more thick starting at the soil surface and immediately Limnic Ornithic overlying ice, continuous rock, or fragmental materials, the Lignic Calcaric interstices of which are filled with organic material; or Fibric Sodic 2. cumulatively within 100 cm of the soil surface either 60 cm or more thick if 75 percent (by volume) or more of the material consists of Hemic Alcalic moss fibres or 40 cm or more thick in other materials and starting within 40 cm of the soil surface. Sapric Toxic HISTOSOLS Floatic Dystric Subaquatic Eutric Glacic Turbic Ombric Gelic Rheic Petrogleyic Technic Placic Cryic Drainic Leptic Transportic Vitric Novic Andic Salic Calcic Other soils having Hydragric Sodic 1. either a hortic, irragric, plaggic or terric horizon 50 cm or more Irragric Alcalic thick; or Terric Dystric 2. an anthraquic horizon and an underlying hydragric horizon with a Plaggic Eutric combined thickness of 50 cm or more. Hortic Oxyaquic ANTHROSOLS Escalic Arenic Technic Siltic Fluvic Clayic Salic Novic Gleyic Stagnic Spodic Ferralic Regic
255 54 World reference base for soil resources 2006
Key to the reference soil groups Prefix qualifiers Suffix qualifiers Other soils having Ekranic Calcaric 1. 20 percent or more (by volume, by weighted average) artefacts in Linic Ruptic the upper 100 cm from the soil surface or to continuous rock or a Urbic Toxic cemented or indurated layer, whichever is shallower; or Spolic Reductic 2. a continuous, very slowly permeable to impermeable, constructed geomembrane of any thickness starting within 100 cm of the soil Garbic Humic surface; or Folic Densic 3. technic hard rock starting within 5 cm of the soil surface and Histic Oxyaquic covering 95 percent or more of the horizontal extent of the soil. Cryic Skeletic TECHNOSOLS1 Leptic Arenic Fluvic Siltic Gleyic Clayic Vitric Drainic Stagnic Novic Mollic Alic Acric Luvic Lixic Umbric Other soils having Glacic Gypsiric 1. a cryic horizon starting within 100 cm of the soil surface; or Turbic Calcaric 2. a cryic horizon starting within 200 cm of the soil surface and Folic Ornithic evidence of cryoturbation2 in some layer within 100 cm of the soil Histic Dystric surface. Technic Eutric CRYOSOLS Hyperskeletic Reductaquic Leptic Oxyaquic Natric Thixotropic Salic Aridic Vitric Skeletic Spodic Arenic Mollic Siltic Calcic Clayic Umbric Drainic Cambic Novic Haplic Other soils having Nudilithic Brunic 1. one of the following: Lithic Gypsiric a. limitation of depth by continuous rock within 25 cm of the soil Hyperskeletic Calcaric surface; or Rendzic Ornithic b. less than 20 percent (by volume) fine earth averaged over a depth Folic Tephric of 75 cm from the soil surface or to continuous rock, whichever is shallower; and Histic Humic 2. no calcic, gypsic or spodic horizon. Technic Sodic LEPTOSOLS Vertic Dystric Salic Eutric Gleyic Oxyaquic Vitric Gelic Andic Placic Stagnic Greyic Mollic Yermic Umbric Aridic Cambic Skeletic Haplic Drainic Novic 1 Buried layers occur frequently in this RSG and can be indicated with the specifier thapto- followed by a qualifier or a RSG. 2 Evidence of cryoturbation includes frost heave, cryogenic sorting, thermal cracking, ice segregation, patterned ground, etc.
256 Chapter 3 – Key to the reference soil groups of the WRB with lists of prefix and suffix qualifiers 55
Key to the reference soil groups Prefix qualifiers Suffix qualifiers Other soils having Grumic Thionic 1. a vertic horizon starting within 100 cm of the soil surface; and Mazic Albic 2. after the upper 20 cm have been mixed, 30 percent or more clay Technic Manganesic between the soil surface and the vertic horizon throughout; and Endoleptic Ferric 3. cracks1 that open and close periodically. Salic Gypsiric VERTISOLS Gleyic Calcaric Sodic Humic Stagnic Hyposalic Mollic Hyposodic Gypsic Mesotrophic Duric Eutric Calcic Pellic Haplic Chromic Novic Other soils having Subaquatic Thionic 1. fluvic material starting within 25 cm of the soil surface or starting Tidalic Anthric immediately below a plough layer of any depth and continuing to a Limnic Gypsiric depth of 50 cm or more; and Folic Calcaric 2. no layers with andic or vitric properties with a combined thickness of 30 cm or more within 100 cm of the soil surface and starting within Histic Tephric 25 cm of the soil surface. Technic Petrogleyic FLUVISOLS2 Salic Gelic Gleyic Oxyaquic Stagnic Humic Mollic Sodic Gypsic Dystric Calcic Eutric Umbric Greyic Haplic Takyric Yermic Aridic Skeletic Arenic Siltic Clayic Drainic Other soils having a natric horizon starting within 100 cm of the soil surface. Technic Glossalbic SOLONETZ Vertic Albic Gleyic Abruptic Salic Colluvic Stagnic Ruptic Mollic Magnesic Gypsic Humic Duric Oxyaquic Petrocalcic Takyric Calcic Yermic Haplic Aridic Arenic Siltic Clayic Novic 1 A crack is a separation between big blocks of soil. If the surface is self-mulching, or if the soil is cultivated while cracks are open, the cracks may be filled mainly by granular materials from the soil surface but they are open in the sense that the blocks are separated; it controls the infiltration and percolation of water. If the soil is irrigated, the upper 50 cm has a COLE of 0.06 or more. 2 Buried layers occur frequently in this RSG and can be indicated with the specifier thapto- followed by a qualifier or a RSG. 257 56 World reference base for soil resources 2006
Key to the reference soil groups Prefix qualifiers Suffix qualifiers Other soils having Petrosalic Sodic 1. a salic horizon starting within 50 cm of the soil surface; and Hypersalic Aceric 2. no thionic horizon starting within 50 cm of the soil surface. Puffic Chloridic SOLONCHAKS Folic Sulphatic Histic Carbonatic Technic Gelic Vertic Oxyaquic Gleyic Takyric Stagnic Yermic Mollic Aridic Gypsic Arenic Duric Siltic Calcic Clayic Haplic Drainic Novic Other soils having Folic Thionic 1. within 50 cm of the mineral soil surface in some parts reducing Histic Abruptic conditions and in half or more of the soil volume a gleyic colour Anthraquic Calcaric pattern; and Technic Tephric 2. no layers with andic or vitric properties with a combined thickness of either Endosalic Colluvic a. 30 cm or more within 100 cm of the soil surface and starting within Vitric Humic 25 cm of the soil surface; or Andic Sodic b. 60 percent or more of the entire thickness of the soil when continuous rock or a cemented or indurated layer is starting Spodic Alcalic between 25 and 50 cm from the soil surface. Plinthic Alumic GLEYSOLS Mollic Toxic Gypsic Dystric Calcic Eutric Alic Petrogleyic Acric Turbic Luvic Gelic Lixic Greyic Umbric Takyric Haplic Arenic Siltic Clayic Drainic Novic
258 Chapter 3 – Key to the reference soil groups of the WRB with lists of prefix and suffix qualifiers 57
Key to the reference soil groups Prefix qualifiers Suffix qualifiers Other soils having Vitric Anthric 1. one or more layers with andic or vitric properties with a combined Aluandic Fragic thickness of either Eutrosilic Calcaric a. 30 cm or more within 100 cm of the soil surface and starting Silandic Colluvic within 25 cm of the soil surface; or Melanic Acroxic b. 60 percent or more of the entire thickness of the soil when continuous rock or a cemented or indurated layer is starting Fulvic Sodic between 25 and 50 cm from the soil surface; and Hydric Dystric 2. no argic, ferralic, petroplinthic, pisoplinthic, plinthic or spodic horizon (unless buried deeper than 50 cm). Folic Eutric ANDOSOLS1 Histic Turbic Technic Gelic Leptic Oxyaquic Gleyic Placic Mollic Greyic Gypsic Thixotropic Petroduric Skeletic Duric Arenic Calcic Siltic Umbric Clayic Drainic Novic Other soils having a spodic horizon starting within 200 cm of the mineral Placic Hortic soil surface. Ortsteinic Plaggic PODZOLS Carbic Terric Rustic Anthric Entic Ornithic Albic Fragic Folic Ruptic Histic Turbic Technic Gelic Hyperskeletic Oxyaquic Leptic Lamellic Gleyic Skeletic Vitric Drainic Andic Novic Stagnic Umbric Haplic
1 Buried layers occur frequently in this RSG and can be indicated with the specifier thapto- followed by a qualifier or a RSG.
259 58 World reference base for soil resources 2006
Key to the reference soil groups Prefix qualifiers Suffix qualifiers Other soils having either Petric Albic 1. a plinthic, petroplinthic or pisoplinthic horizon starting within 50 cm Fractipetric Manganiferric of the soil surface; or Pisolithic Ferric 2. a plinthic horizon starting within 100 cm of the soil surface and, Gibbsic Endoduric directly above, a layer 10 cm or more thick, that has in some parts reducing conditions for some time during the year and in half or Posic Abruptic more of the soil volume, single or in combination Geric Colluvic a. a stagnic colour pattern; or Vetic Ruptic b. an albic horizon. Folic Alumic Histic Humic PLINTHOSOLS Technic Dystric Stagnic Eutric Acric Oxyaquic Lixic Pachic Umbric Umbriglossic Haplic Arenic Siltic Clayic Drainic Novic Other soils having Vetic Humic 1. a nitic horizon starting within 100 cm of the soil surface; and Technic Alumic 2. gradual to diffuse1 horizon boundaries between the soil surface and Andic Dystric the nitic horizon; and Ferralic Eutric 3. no ferric, petroplinthic, pisoplinthic, plinthic or vertic horizon Mollic Oxyaquic starting within 100 cm of the soil surface; and Alic Colluvic 4. no gleyic or stagnic colour pattern starting within 100 cm of the soil surface. Acric Rhodic NITISOLS Luvic Novic Lixic Umbric Haplic Other soils having Gibbsic Sombric 1. a ferralic horizon starting within 150 cm of the soil surface; and Posic Manganiferric 2. no argic horizon that has, in the upper 30 cm, 10 percent or more Geric Ferric water-dispersible clay unless the upper 30 cm of the argic horizon Vetic Colluvic has one or both of the following: Folic Humic a. geric properties; or Technic Alumic b. 1.4 percent or more organic carbon. Andic Dystric FERRALSOLS Plinthic Eutric Mollic Ruptic Acric Oxyaquic Lixic Arenic Umbric Siltic Haplic Clayic Rhodic Xanthic Novic
1 As defined in FAO (2006).
260 Chapter 3 – Key to the reference soil groups of the WRB with lists of prefix and suffix qualifiers 59
Key to the reference soil groups Prefix qualifiers Suffix qualifiers Other soils having Solodic Thionic 1. an abrupt textural change within 100 cm of the soil surface and, Folic Albic directly above or below, a layer 5 cm or more thick, that has in some Histic Manganiferric parts reducing conditions for some time during the year and in half or more of the soil volume, single or in combination Technic Ferric a. a stagnic colour pattern; or Vertic Geric b. an albic horizon; and Endosalic Ruptic 2. no albeluvic tonguing starting within 100 cm of the soil surface. Plinthic Calcaric PLANOSOLS Endogleyic Sodic Mollic Alcalic Gypsic Alumic Petrocalcic Dystric Calcic Eutric Alic Gelic Acric Greyic Luvic Arenic Lixic Siltic Umbric Clayic Haplic Chromic Drainic Novic Other soils having Folic Thionic 1. within 50 cm of the mineral soil surface in some parts reducing Histic Albic conditions for some time during the year and in half or more of the Technic Manganiferric soil volume, single or in combination, Vertic Ferric a. a stagnic colour pattern; or Endosalic Ruptic b. an albic horizon; and Plinthic Geric 2. no albeluvic tonguing starting within 100 cm of the soil surface. Endogleyic Calcaric STAGNOSOLS Mollic Ornithic Gypsic Sodic Petrocalcic Alcalic Calcic Alumic Alic Dystric Acric Eutric Luvic Gelic Lixic Greyic Umbric Placic Haplic Arenic Siltic Clayic Rhodic Chromic Drainic Novic
261 60 World reference base for soil resources 2006
Key to the reference soil groups Prefix qualifiers Suffix qualifiers Other soils having Voronic Anthric 1. a mollic horizon with a moist chroma of 2 or less to a depth of Vermic Glossic 20 cm or more, or having this chroma directly below any plough Technic Tephric layer that is 20 cm or more deep; and Leptic Sodic 2. a calcic horizon, or concentrations of secondary carbonates starting within 50 cm below the lower limit of the mollic horizon and, if Vertic Pachic present, above a cemented or indurated layer; and Endofluvic Oxyaquic 3. a base saturation (by 1 M NH4OAc) of 50 percent or more from the Endosalic Greyic soil surface to the calcic horizon or the concentrations of secondary carbonates throughout. Gleyic Skeletic CHERNOZEMS Vitric Arenic Andic Siltic Stagnic Clayic Petrogypsic Novic Gypsic Petroduric Duric Petrocalcic Calcic Luvic Haplic Other soils having Vermic Anthric 1. a mollic horizon; and Technic Glossic 2. a calcic horizon, or concentrations of secondary carbonates starting Leptic Tephric within 50 cm below the lower limit of the mollic horizon and, if Vertic Sodic present, above a cemented or indurated layer; and Endosalic Oxyaquic 3. a base saturation (by 1 M NH4OAc) of 50 percent or more from the soil surface to the calcic horizon or the concentrations of secondary Gleyic Greyic carbonates throughout. Vitric Skeletic KASTANOZEMS Andic Arenic Stagnic Siltic Petrogypsic Clayic Gypsic Chromic Petroduric Novic Duric Petrocalcic Calcic Luvic Haplic Other soils having Vermic Anthric 1. a mollic horizon; and Greyic Albic
2. a base saturation (by 1 M NH4OAc) of 50 percent or more Technic Abruptic throughout to a depth of 100 cm or more from the soil surface or Rendzic Glossic to continuous rock or a cemented or indurated layer, whichever is shallower. Leptic Calcaric PHAEOZEMS Vertic Tephric Endosalic Sodic Gleyic Pachic Vitric Oxyaquic Andic Skeletic Ferralic Arenic Stagnic Siltic Petrogypsic Clayic Petroduric Chromic Duric Novic Petrocalcic Calcic Luvic Haplic
262 Chapter 3 – Key to the reference soil groups of the WRB with lists of prefix and suffix qualifiers 61
Key to the reference soil groups Prefix qualifiers Suffix qualifiers Other soils having Petric Ruptic 1. a petrogypsic horizon starting within 100 cm of the soil surface; or Hypergypsic Sodic 2. a gypsic horizon starting within 100 cm of the soil surface and no Hypogypsic Hyperochric argic horizon unless the argic horizon is permeated with gypsum or Arzic Takyric calcium carbonate. Technic Yermic GYPSISOLS Leptic Aridic Vertic Skeletic Endosalic Arenic Endogleyic Siltic Petroduric Clayic Duric Novic Petrocalcic Calcic Luvic Haplic Other soils having a petroduric or duric horizon starting within 100 cm of Petric Ruptic the soil surface. Fractipetric Sodic DURISOLS Technic Takyric Leptic Yermic Vertic Aridic Endogleyic Hyperochric Gypsic Arenic Petrocalcic Siltic Calcic Clayic Luvic Chromic Lixic Novic Haplic Other soils having Petric Ruptic 1. a petrocalcic horizon starting within 100 cm of the soil surface; or Hypercalcic Sodic 2. a calcic horizon starting within 100 cm of the soil surface and Hypocalcic Takyric a. a calcareous matrix between 50 cm from the soil surface and Technic Yermic the calcic horizon throughout if the calcic horizon starts below Leptic Aridic 50 cm; and Vertic Hyperochric b. no argic horizon unless the argic horizon is permeated with calcium carbonate. Endosalic Skeletic CALCISOLS Endogleyic Arenic Gypsic Siltic Luvic Clayic Lixic Chromic Haplic Novic Other soils having an argic horizon starting within 100 cm of the soil Fragic Anthric surface with albeluvic tonguing at its upper boundary. Cutanic Manganiferric ALBELUVISOLS Folic Ferric Histic Abruptic Technic Ruptic Gleyic Alumic Stagnic Dystric Umbric Eutric Haplic Gelic Oxyaquic Greyic Arenic Siltic Clayic Drainic Novic 263 62 World reference base for soil resources 2006
Key to the reference soil groups Prefix qualifiers Suffix qualifiers Other soils having Hyperalic Anthric
-1 1. an argic horizon, which has a CEC (by 1 M NH4OAc) of 24 cmolc kg Lamellic Fragic clay1 or more throughout or to a depth of 50 cm below its upper Cutanic Manganiferric limit, whichever is shallower, either starting within 100 cm of the soil surface, or within 200 cm of the soil surface if the argic horizon is Albic Ferric overlain by loamy sand or coarser textures throughout; and Technic Abruptic
2. a base saturation (by 1 M NH4OAc) of less than 50 percent in the major part between 50 and 100 cm. Leptic Ruptic ALISOLS Vertic Alumic Fractiplinthic Humic Petroplinthic Hyperdystric Pisoplinthic Epieutric Plinthic Turbic Gleyic Gelic Vitric Oxyaquic Andic Greyic Nitic Profondic Stagnic Hyperochric Umbric Skeletic Haplic Arenic Silltic Clayic Rhodic Chromic Novic Other soils having Vetic Anthric
1. an argic horizon that has a CEC (by 1 M NH4OAc) of less than Lamellic Albic 24 cmol kg-1 clay2 in some part to a maximum depth of 50 cm below c Cutanic Fragic its upper limit, either starting within 100 cm of the soil surface, or within 200 cm of the soil surface if the argic horizon is overlain by Technic Sombric loamy sand or coarser textures throughout, and Leptic Manganiferric
2. a base saturation (by 1 M NH4OAc) of less than 50 percent in the major part between 50 and 100 cm. Fractiplinthic Ferric ACRISOLS Petroplinthic Abruptic Pisoplinthic Ruptic Plinthic Alumic Gleyic Humic Vitric Hyperdystric Andic Epieutric Nitic Oxyaquic Stagnic Greyic Umbric Profondic Haplic Hyperochric Skeletic Arenic Siltic Clayic Rhodic Chromic Novic 1 See Annex 1. 2 See Annex 1.
264 Chapter 3 – Key to the reference soil groups of the WRB with lists of prefix and suffix qualifiers 63
Key to the reference soil groups Prefix qualifiers Suffix qualifiers
Other soils having an argic horizon with a CEC (by 1 M NH4OAc) of Lamellic Anthric 24 cmol kg-1 clay1 or more throughout or to a depth of 50 cm below its c Cutanic Fragic upper limit, whichever is shallower, either starting within 100 cm of the soil surface or within 200 cm of the soil surface if the argic horizon is Albic Manganiferric overlain by loamy sand or coarser textures throughout. Escalic Ferric LUVISOLS Technic Abruptic Leptic Ruptic Vertic Humic Gleyic Sodic Vitric Epidystric Andic Hypereutric Nitic Turbic Stagnic Gelic Calcic Oxyaquic Haplic Greyic Profondic Hyperochric Skeletic Arenic Siltic Clayic Rhodic Chromic Novic Other soils having an argic horizon, either starting within 100 cm of the Vetic Anthric soil surface or within 200 cm of the soil surface if the argic horizon is Lamellic Albic overlain by loamy sand or coarser textures throughout. Cutanic Fragic LIXISOLS Technic Manganiferric Leptic Ferric Gleyic Abruptic Vitric Ruptic Andic Humic Fractiplinthic Epidystric Petroplinthic Hypereutric Pisoplinthic Oxyaquic Plinthic Greyic Nitic Profondic Stagnic Hyperochric Calcic Skeletic Haplic Arenic Siltic Clayic Rhodic Chromic Novic
1 See Annex 1.
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Key to the reference soil groups Prefix qualifiers Suffix qualifiers Other soils having an umbric or mollic horizon. Folic Anthric UMBRISOLS Histic Albic Technic Brunic Leptic Ornithic Vitric Thionic Andic Glossic Endogleyic Humic Ferralic Alumic Stagnic Hyperdystric Mollic Endoeutric Cambic Pachic Haplic Turbic Gelic Oxyaquic Greyic Laxic Placic Skeletic Arenic Siltic Clayic Chromic Drainic Novic Other soils having Lamellic Ornithic 1. a weighted average texture of loamy sand or coarser, if cumulative Hypoluvic Gypsiric layers of finer texture are less than 15 cm thick, either to a depth Hyperalbic Calcaric of 100 cm from the soil surface or to a petroplinthic, pisoplinthic, plinthic or salic horizon starting between 50 and 100 cm from the Albic Tephric soil surface; and Rubic Hyposalic 2. less than 40 percent (by volume) of gravels or coarser fragments in all layers within 100 cm of the soil surface or to a petroplinthic, Brunic Dystric pisoplinthic, plinthic or salic horizon starting between 50 and 100 cm Hydrophobic Eutric from the soil surface; and Protic Petrogleyic 3. no fragic, irragric, hortic, plaggic or terric horizon; and Folic Turbic 4. no layers with andic or vitric properties with a combined thickness of 15 cm. Technic Gelic ARENOSOLS Endosalic Greyic Endogleyic Placic Fractiplinthic Hyperochric Petroplinthic Yermic Pisoplinthic Aridic Plinthic Transportic Ferralic Novic Haplic
266 Chapter 3 – Key to the reference soil groups of the WRB with lists of prefix and suffix qualifiers 65
Key to the reference soil groups Prefix qualifiers Suffix qualifiers Other soils having Folic Fragic 1. a cambic horizon starting within 50 cm of the soil surface and having Anthraquic Manganiferric its base 25 cm or more below the soil surface or 15 cm or more Hortic Ferric below any plough layer; or Irragric Ornithic 2. an anthraquic, hortic, hydragric, irragric, plaggic or terric horizon; or Plaggic Ruptic 3. a fragic, petroplinthic, pisoplinthic, plinthic, salic or vertic horizon starting within 100 cm of the soil surface; or Terric Colluvic 4. one or more layers with andic or vitric properties with a combined Technic Gypsiric thickness of 15 cm or more within 100 cm of the soil surface. Leptic Calcaric CAMBISOLS Vertic Tephric Fluvic Alumic Endosalic Sodic Vitric Alcalic Andic Humic Endogleyic Dystric Fractiplinthic Eutric Petroplinthic Laxic Pisoplinthic Turbic Plinthic Gelic Ferralic Oxyaquic Gelistagnic Greyic Stagnic Hyperochric Haplic Takyric Yermic Aridic Skeletic Siltic Clayic Rhodic Chromic Escalic Novic Other soils. Aric Ornithic REGOSOLS Colluvic Gypsiric Technic Calcaric Leptic Tephric Endogleyic Humic Thaptovitric Hyposalic Thaptandic Sodic Gelistagnic Dystric Stagnic Eutric Haplic Turbic Gelic Oxyaquic Vermic Hyperochric Takyric Yermic Aridic Skeletic Arenic Siltic Clayic Escalic Transportic
267 268 67
Chapter 4 Description, distribution, use and management of reference soil groups
This chapter gives an overview of all the RSGs recognized in the WRB. A brief description is provided with corresponding names in other major soil classification systems, followed by the regional distribution of each group. Land use and management concludes each description. More detailed information on each RSG, including morphological, chemical and physical characteristics and genesis, is available in FAO (2001a) and a number of CD-ROMs (FAO, 2001b, 2003 and 2005). All these publications reflect the first edition of the WRB (FAO, 1998); new publications based on the current second edition are planned for the near future.
ACRISOLS
Acrisols are soils that have a higher clay content in the subsoil than in the topsoil as a result of pedogenetic processes (especially clay migration) leading to an argic subsoil horizon. Acrisols have in certain depths a low base saturation and low-activity clays. Many Acrisols correlate with Red Yellow Podzolic soils (e.g. Indonesia), Argissolos (Brazil), sols ferralitiques fortement ou moyennement désaturés (France), Red and Yellow Earths, and Ultisols with low-activity clays (United States of America).
Summary description of Acrisols Connotation: From Latin acer, very acid. Strongly weathered acid soils with low base saturation at some depth. Parent material: On a wide variety of parent materials, most extensive from weathering of acid rocks, and notably in strongly weathered clays that are undergoing further degradation. Environment: Mostly old land surfaces with hilly or undulating topography, in regions with a wet tropical/monsoonal, subtropical or warm temperate climate. Forest is the natural vegetation type. Profile development: Pedogenetic differentiation of clay content with a lower content in the topsoil and a higher content in the subsoil; leaching of base cations owing to the humid environment and advanced degree of weathering.
Regional distribution of Acrisols Acrisols are found in humid tropical, humid subtropical and warm temperate regions and are most extensive in Southeast Asia, the southern fringes of the Amazon Basin, the southeast of the United States of America, and in both East and West Africa. There are about 1 000 million ha of Acrisols worldwide.
Management and use of Acrisols Preservation of the surface soil with its all-important organic matter and preventing erosion are preconditions for farming on Acrisols. Mechanical clearing of natural forest by extraction of root balls and filling of the holes with surrounding surface soil
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produces land that is largely sterile where Al concentrations of the former subsoil reach toxic levels. Adapted cropping systems with complete fertilization and careful management are required if sedentary farming is to be practised on Acrisols. The widely used slash-and- burn agriculture (shifting cultivation) may seem primitive but it is a well-adapted form of land use, developed over centuries of trial and error. If occupation periods are short (one or a few years only) and followed by a sufficiently long generation period (up to several decades), this system makes a good use of the limited resources of Acrisols. Agroforestry is recommended as a soil-protecting alternative to shifting cultivation to achieve higher yields without requiring expensive inputs. Low-input farming on Acrisols is not very rewarding. Undemanding, acidity- tolerant cash crops such as pineapple, cashew, tea and rubber can be grown with some success. Increasing areas of Acrisols are planted to oil-palm (e.g. in Malaysia and on Sumatra). Large areas of Acrisols are under forest, ranging from high, dense rain forest to open woodland. Most of the tree roots are concentrated in the humous surface horizon with only a few tap-roots extending down into the subsoil. In South America, Acrisols are also found under savannah. Acrisols are suitable for production of rainfed and irrigated crops only after liming and full fertilization. Rotation of annual crops with improved pasture maintains the organic matter content.
ALBELUVISOLS
Albeluvisols are soils that have, beginning within 1 m of the soil surface, a clay illuviation horizon with an irregular or broken upper boundary resulting in tonguing of bleached soil material into the illuviation horizon. Many Albeluvisols correlate with: Podzoluvisols (FAO); Sod-podzolic or Podzolic soils (Russian Federation); Fahlerden (Germany); and Glossaqualfs, Glossocryalfs and Glossudalfs (United States of America).
Summary description of Albeluvisols Connotation: From Latin albus, white, and Latin eluere, to wash out. Parent material: Mostly unconsolidated glacial till, materials of lacustrine or fluvial origin and aeolian deposits (loess). Environment: Flat to undulating plains under coniferous forest (including boreal taiga) or mixed forest. The climate is temperate to boreal with cold winters, short and cool summers, and an average annual precipitation sum of 500–1 000 mm. Precipitation is distributed evenly over the year or, in the continental part of the Albeluvisol belt, has a peak in early summer. Profile development: A thin, dark surface horizon over an albic subsurface horizon that tongues into an underlying brown argic horizon. Temporarily reducing conditions with a stagnic colour pattern are common in boreal Albeluvisols.
Regional distribution of Albeluvisols Albeluvisols cover an estimated 320 million ha in Europe, North Asia and Central Asia, with minor occurrences in North America. Albeluvisols are concentrated in two regions, each having a particular set of climate conditions: ÿ the continental regions that had permafrost in the Pleistocene of northeast Europe, northwest Asia and southwest Canada, which constitute by far the largest areas of Albeluvisols; ÿ the loess and cover sand areas and old alluvial areas in moist temperate regions, such as France, central Belgium, the southeast of the Netherlands and the west of Germany.
270 Chapter 4 – Description, distribution, use and management of reference soil groups 69
Management and use of Albeluvisols The agricultural suitability of Albeluvisols is limited because of their acidity, low nutrient levels, tillage and drainage problems and because of the climate, with its short growing season and severe frost during the long winter. The Albeluvisols of the northern taiga zone are almost exclusively under forest; small areas are used as pasture or hay fields. In the southern taiga zone, less than 10 percent of the non-forested area is used for agricultural production. Livestock farming is the main agricultural land use on Albeluvisols (dairy production and cattle rearing); arable cropping (cereals, potatoes, sugar beet and forage maize) plays a minor role. In the Russian Federation, the share of arable farming increases in southern and western directions, especially on Albeluvisols with higher base saturations in the subsoil. With careful tillage, liming and application of fertilizers, Albeluvisols can produce 25–30 tonnes of potatoes per hectare, 2–5 tonnes of winter wheat or 5–10 tonnes of dry herbage.
ALISOLS
Alisols are soils that have a higher clay content in the subsoil than in the topsoil as a result of pedogenetic processes (especially clay migration) leading to an argic subsoil horizon. Alisols have a low base saturation at certain depths and high-activity clays throughout the argic horizon. They lack the albeluvic tonguing as in Albeluvisols. They occur predominantly in humid tropical, humid subtropical and warm temperate regions. Many Alisols correlate with: Alissolos (Brazil); Ultisols with high-activity clays (United States of America); Kurosols (Australia); and Fersialsols and sols fersiallitiques très lessivés (France).
Summary description of Alisols Connotation: Soils with a low base saturation at some depths; from Latin alumen, alum. Parent material: In a wide variety of parent materials. Most occurrences of Alisols reported so far are on weathering products of basic rocks and unconsolidated materials. Environment: Most common in hilly or undulating topography, in humid tropical, humid subtropical and monsoon climates. Profile development: Pedogenetic differentiation of clay contents with a lower content in the topsoil and a higher content in the subsoil, leaching of base cations owing to the humid environment without advanced weathering of high-activity clays; highly leached Alisols might have an albic eluviation horizon between the surface horizon and the argic subsurface horizon but lack the albeluvic tonguing of Albeluvisols.
Regional distribution of Alisols Major occurrences of Alisols are found in Latin America (Ecuador, Nicaragua, Venezuela, Colombia, Peru and Brazil), in the West Indies (Jamaica, Martinique and Saint Lucia), in West Africa, the highlands of East Africa, Madagascar, and in Southeast Asia and northern Australia. FAO (2001a) estimates that about 100 million ha of these soils are used for agriculture in the tropics. Alisols occur also in subtropical regions; they are found in China, Japan and the southeast of the United States of America, and minor occurrences have been reported from around the Mediterranean Sea (Italy, France and Greece). They also occur in humid temperate regions.
Management and use of Alisols Alisols occur predominantly on hilly or undulating topography. The generally unstable surface soil of cultivated Alisols makes them susceptible to erosion; truncated soils 271 70 World reference base for soil resources 2006
are quite common. Toxic levels of Al at shallow depth and poor natural soil fertility are added constraints in many Alisols. As a consequence, many Alisols allow only cultivation of shallow-rooting crops and crops suffer from drought stress in the dry season. A significant part of the Alisols is unproductive under a wide variety of crops. The use of acidity-tolerant crops or low-volume grazing is common. The productivity of Alisols in subsistence agriculture is generally low as these soils have a limited capacity to recover from chemical exhaustion. Where fully limed and fertilized, crops on Alisols may benefit from the considerable CEC and good water-holding capacity, and the Alisols may eventually grade into Luvisols. Alisols are increasingly planted to Al-tolerant estate crops such as tea and rubber but also to oil-palm and, in places, to coffee and sugar cane.
ANDOSOLS
Andosols accommodate the soils that develop in volcanic ejecta or glasses under almost any climate (except under hyperarid climate conditions). However, Andosols may also develop in other silicate-rich materials under acid weathering in humid and perhumid climates. Many Andosols belong to: Kuroboku (Japan); Andisols (United States of America); Andosols and Vitrisols (France); and volcanic ash soils.
Summary description of Andosols Connotation: Typically black soils of volcanic landscapes; from Japanese an, black, and do, soil. Parent material: Volcanic glasses and ejecta (mainly ash, but also tuff, pumice, cinders and others) or other silicate-rich material. Environment: Undulating to mountainous, humid, and arctic to tropical regions with a wide range of vegetation types. Profile development: Rapid weathering of porous volcanic ejecta or glasses results in accumulation of stable organo-mineral complexes or short-range-order minerals such as allophane, imogolite and ferrihydrite. Acid weathering of other silicate-rich material in humid and perhumid climates also leads to the formation of stable organo-mineral complexes.
Regional distribution of Andosols Andosols occur in volcanic regions all over the world. Important concentrations are found around the Pacific rim: on the west coast of South America, in Central America, Mexico, United States of America (the Rocky Mountains, Alaska), Japan, the Philippine Archipelago, Indonesia, Papua New Guinea, and New Zealand. They are also prominent on many islands in the Pacific: Fiji, Vanuatu, New Caledonia, Samoa and Hawaii. In Africa, major occurrences of Andosols are found along the Rift Valley, in Kenya, Rwanda and Ethiopia and in Madagascar. In Europe, Andosols occur in Italy, France, Germany and Iceland. The total Andosol area is estimated at some 110 million ha or less than 1 percent of the global land surface. More than half of this area is situated in the tropics. Andosols originating from parent materials other than volcanic ejecta or glasses occur in humid (often mountainous) regions.
Management and use of Andosols Andosols have a high potential for agricultural production, but many of them are not used up to their capacity. Andosols are generally fertile soils, particularly Andosols in intermediate or basic volcanic ash and not exposed to excessive leaching. The strong phosphate fixation of Andosols (caused by active Al and Fe) is a problem. Ameliorative measures to reduce this effect include application of lime, silica, organic material, and phosphate fertilizer. 272 Chapter 4 – Description, distribution, use and management of reference soil groups 71
Andosols are easy to cultivate and have good rootability and water storage properties. Strongly hydrated Andosols are difficult to till because of their low bearing capacity and their stickiness. Andosols are planted to a wide variety of crops including sugar cane, tobacco, sweet potato (tolerant of low phosphate levels), tea, vegetables, wheat and orchard crops. Andosols on steep slopes are perhaps best kept under forest. Paddy rice cultivation is a major land use on Andosols in lowlands with shallow groundwater.
ANTHROSOLS
Anthrosols comprise soils that have been modified profoundly through human activities, such as addition of organic materials or household wastes, irrigation and cultivation. The group includes soils otherwise known as: Plaggen soils, Paddy soils, Oasis soils, Terra Preta do Indio (Brazil), Agrozems (Russian Federation), Terrestrische anthropogene Böden (Germany), Anthroposols (Australia), and Anthrosols (China).
Summary description of Anthrosols Connotation: Soils with prominent characteristics that result from human activities; from Greek anthropos, human being. Parent material: Virtually any soil material, modified by long-continued cultivation or addition of material. Environment: In many regions where people have been practising agriculture for a long time. Profile development: Influence of humans is normally restricted to the surface horizons; the horizon differentiation of a buried soil may still be intact at some depth.
Regional distribution of Anthrosols Anthrosols are found wherever people have practised agriculture for a long time. Anthrosols with plaggic horizons are most common in northwest Europe. Together with Anthrosols with a terric horizon, they cover more than 500 000 ha. Anthrosols with irragric horizons are found in irrigation areas in dry regions, e.g. in Mesopotamia, near oases in desert regions and in parts of India. Anthrosols with an anthraquic horizon overlying a hydragric horizon (paddy soils) occupy vast areas in China and in parts of South and Southeast Asia (e.g. Sri Lanka, Viet Nam, Thailand and Indonesia). Anthrosols with hortic horizons are found all over the world where humans have fertilized the soil with household wastes and manure. The Terra Preta do Indio in the Amazon Region of Brazil belongs to this group.
Management and use of Anthrosols Plaggic horizons have favourable physical properties (porosity, rootability and moisture availability), but many have less satisfactory chemical characteristics (acidity, and nutrient deficiencies). Rye, oats, barley, potato, and also the more demanding sugar beet and summer wheat are common crops on European Anthrosols with a plaggic horizon. Prior to the advent of chemical fertilizers, rye yields were 700–1 100 kg/ha, or 4–5 times the quantity of seed used. Today, these soils receive generous doses of fertilizers and average per-hectare yield levels for rye, barley and summer wheat are 5 000, 4 500 and 5 500 kg, respectively. Sugar beet and potato produce 40–50 tonnes/ ha. Nowadays, they are increasingly used for production of silage maize and grass; per-hectare production levels of 12–13 tonnes of dry maize silage and 10–13 tonnes of dry grass are considered normal. In places, Anthrosols with plaggic horizons are used for tree nurseries and horticulture. The good drainage and the dark colour of the surface soil (early warming in spring) make it possible to till and sow or plant early in 273 72 World reference base for soil resources 2006
the season. Soils with deep plaggic horizons in the Netherlands were in demand for the cultivation of tobacco until the 1950s. Anthrosols with a hortic horizon are kitchen soils. Well-known examples are situated on river terraces in south Maryland, United States of America, and along the Amazon River in Brazil. They have deep, black topsoils formed in layers of kitchen refuse (mainly oyster shells, fish bones, etc.) from early Indian habitations. Many countries possess small areas of soils that were modified by early inhabitants. Long-continued wet cultivation of rice leads to an anthraquic horizon with an underlying hydragric horizon. Puddling of wetland rice fields (involving destruction of the natural soil structure by intensive tillage when the soil is saturated with water) is done intentionally, inter alia to reduce percolation losses. Anthrosols with irragric horizons are formed as a result of prolonged sedimentation (predominantly silt) from irrigation water. A special case is found in depression areas where dryland crops are commonly planted on constructed ridges that alternate with drainage furrows. The original soil profile of the ridge areas is buried under a thick layer of added soil material. The ridge-and-furrow system is known from such different environments as the wet forests of western Europe and the coastal swamps of Southeast Asia where the ridges are planted to dryland crops and rice is grown in the shallow ditch areas. In parts of western Europe, notably in Ireland and the United Kingdom, calcareous materials (e.g. beach sands) were carted to areas with acid Arenosols, Podzols, Albeluvisols and Histosols. Eventually these modified surface layers of mineral material turned into terric horizons that give the soil much improved properties for arable cropping than the original surface soil. In Central Mexico, deep soils were constructed of organic-matter-rich lacustrine sediments, thus forming a system of artificial islands and channels (chinampas). These soils have a terric horizon and were the most productive lands of the Aztec empire; now most of these soils are affected by salinization.
ARENOSOLS
Arenosols comprise sandy soils, including both soils developed in residual sands after in situ weathering of usually quartz-rich sediments or rock, and soils developed in recently deposited sands such as dunes in deserts and beach lands. Corresponding soils in other classification systems include Psamments of the US Soil Taxonomy and the sols minéraux bruts and sols peu évolués in the French classification system of the CPCS (1967). Many Arenosols belong to Arenic Rudosols (Australia), Psammozems (Russian Federation) and Neossolos (Brazil).
Summary description of Arenosols Connotation: Sandy soils; from Latin arena, sand. Parent material: Unconsolidated, in places calcareous, translocated materials of sandy texture; relatively small areas of Arenosols occur in extremely weathered siliceous rock. Environment: From arid to humid and perhumid, and from extremely cold to extremely hot; landforms vary from recent dunes, beach ridges and sandy plains to very old plateaus; the vegetation ranges from desert over scattered vegetation (mostly grassy) to light forest. Profile development: In the dry zone, there is little or no soil development. Arenosols in the perhumid tropics tend to develop thick albic eluviation horizons (with a spodic horizon below 200 m from the soil surface) whereas most Arenosols of the humid temperate zone show signs of alteration or transport of humus, Fe or clay, but too weak to be diagnostic. 274 Chapter 4 – Description, distribution, use and management of reference soil groups 73
Regional distribution of Arenosols Arenosols are one of the most extensive RSGs in the world; including shifting sands and active dunes, they cover about 1 300 million ha, or 10 percent of the land surface. Vast expanses of deep aeolian sands are found on the Central African plateau between the equator and 30 °S. These Kalahari Sands form the largest body of sands on earth. Other areas of Arenosols occur in the Sahelian region of Africa, various parts of the Sahara, central and western Australia, the Near East, and China. Sandy coastal plains and coastal dune areas are of smaller geographic extent. Although most Arenosols occur in arid and semi-arid regions, they are typical azonal soils; they are found in the widest possible range of climates, from very arid to very humid and from cold to hot. Arenosols are widespread in aeolian landscapes but occur also in marine, littoral, and lacustrine sands and in coarse-grained weathering mantles of siliceous rocks, mainly sandstone, quartzite and granite. There is no limitation as to age or period in which soil formation took place. Arenosols occur on very old surfaces as well as in very recent landforms, and may be associated with almost any type of vegetation.
Management and use of Arenosols Arenosols occur in widely different environments, and possibilities to use them for agriculture vary accordingly. The characteristic that all Arenosols have in common is their coarse texture, accounting for their generally high permeability and low water and nutrient storage capacity. On the other hand, Arenosols offer ease of cultivation, rooting and harvesting of root and tuber crops. Arenosols in arid lands, where the annual rainfall is less than 300 mm, are predominantly used for extensive (nomadic) grazing. Dry farming is possible where the annual rainfall exceeds 300 mm. Low coherence, low nutrient storage capacity and high sensitivity to erosion are serious limitations of Arenosols in the dry zone. Good yields of small grains, melons, pulses and fodder crops have been realized on irrigated Arenosols, but high percolation losses may make surface irrigation impracticable. Drip or trickle irrigation, possibly combined with careful dosage of fertilizers, may remedy the situation. Many areas with Arenosols in the Sahelian zone (annual rainfall of 300–600 mm) are transitional to the Sahara, and their soils are covered with sparse vegetation. Uncontrolled grazing and clearing for cultivation without appropriate soil conservation measures can easily make these soils unstable and revert them to shifting dunes. Arenosols in the humid and subhumid temperate zone have similar limitations as those of the dry zone, albeit that drought is a less serious constraint. In some instances, e.g. in horticulture, the low water storage of Arenosols is considered advantageous because the soils warm up early in the season. In mixed farming systems (which are much more common) with cereals, fodder crops and grassland, supplemental sprinkler irrigation is applied during dry spells. A large part of the Arenosols of the temperate zone is under forest, either production forest or natural stands in carefully managed nature reserves. Arenosols in the humid tropics are best left under their natural vegetation, particularly so the deeply weathered Arenosols with an albic horizon. As nutrient elements are all concentrated in the biomass and in the soil organic matter, clearing of the land will inevitably produce infertile badlands without ecological or economic value. Under forest, the land can still produce some timber (e.g. Agathis spp.) and wood for the pulp and paper industry. Permanent cultivation of annual crops would require management inputs that are usually not economically justifiable. In places, Arenosols have been planted to perennial crops such as rubber and pepper; coastal sands are widely planted to estate crops such as coconut, cashew, casuarinas and pine, especially where good quality groundwater is within reach of the root system. Root 275 74 World reference base for soil resources 2006
and tuber crops benefit from the ease of harvesting, notably cassava, with its tolerance of low nutrient levels. Groundnut and bambara groundnut can be found on the better soils. Arenosols and related soils with a sandy surface texture in some regions (e.g. west Australia and parts of South Africa) may be prone to develop water-repellency, typically caused by hydrophobic exudates of soil fungi that coat sand grains. Water-repellency is most intense after lengthy spells of hot, dry weather and leads to differential water infiltration. This is thought to have ecological significance in promoting plant species diversity (e.g. in Namaqualand). Wetting agents (surfactants such as calcium lignosulphonate) are sometimes used to achieve more uniform water penetration under irrigation. Dryland wheat farmers in Australia mine clay and apply it to their sandy soils with specialized machinery. The results (more uniform germination and better herbicide efficiency) can be economically attractive where a local source of clay is available.
CALCISOLS
Calcisols accommodate soils in which there is substantial secondary accumulation of lime. Calcisols are common in highly calcareous parent materials and widespread in arid and semi-arid environments. Formerly used soil names for many Calcisols include Desert soils and Takyrs. In the US Soil Taxonomy, most of them belong to the Calcids.
Summary description of Calcisols Connotation: Soils with substantial accumulation of secondary lime; from Latin calx, lime. Parent material: Mostly alluvial, colluvial and aeolian deposits of base-rich weathering material. Environment: Level to hilly land in arid and semi-arid regions. The natural vegetation is sparse and dominated by xerophytic shrubs and trees and/or ephemeral grasses. Profile development: Typical Calcisols have a pale brown surface horizon; substantial secondary accumulation of lime occurs within 100 cm of the surface.
Regional distribution of Calcisols It is difficult to quantify the worldwide extent of Calcisols with any measure of accuracy. Many Calcisols occur together with Solonchaks that are actually salt- affected Calcisols and/or with other soils having secondary accumulation of lime that do not key out as Calcisols. The total Calcisol area may well amount to some 1 000 million ha, nearly all of it in the arid and semi-arid tropics and subtropics of both hemispheres.
Land use and management of Calcisols Vast areas of so-called natural Calcisols are under shrubs, grasses and herbs and are used for extensive grazing. Drought-tolerant crops such as sunflower might be grown rainfed, preferably after one or a few fallow years, but Calcisols reach their full productive capacity only where carefully irrigated. Extensive areas of Calcisols are used for production of irrigated winter wheat, melons, and cotton in the Mediterranean zone. Sorghum bicolor (el sabeem) and fodder crops, such as Rhodes grass and alfalfa, are tolerant of high Ca levels. Some 20 vegetable crops have been grown successfully on irrigated Calcisols fertilized with nitrogen (N), phosphorus (P) and trace elements (Fe and zinc [Zn]). Furrow irrigation is superior to basin irrigation on slaking Calcisols because it reduces surface crusting/caking and seedling mortality; pulse crops in particular are 276 Chapter 4 – Description, distribution, use and management of reference soil groups 75
very vul nerable in the seedling stage. In places, arable farming is hindered by stoniness of the surface soil and/or a petrocalcic horizon at shallow depth.
CAMBISOLS
Cambisols combine soils with at least an incipient subsurface soil formation. Transformation of parent material is evident from structure formation and mostly brownish discoloration, increasing clay percentage, and/or carbonate removal. Other soil classification systems refer to many Cambisols as: Braunerden (Germany), Sols bruns (France), Brown soils/Brown Forest soils (older US systems), or Burozems (Russian Federation). FAO coined the name Cambisols, adopted by Brazil (Cambissolos); US Soil Taxonomy classifies most of these soils as Inceptisols.
Summary description of Cambisols Connotation: Soils with at least the beginnings of horizon differentiation in the subsoil evident from changes in structure, colour, clay content or carbonate content; from Italian cambiare, to change. Parent material: Medium and fine-textured materials derived from a wide range of rocks. Profile development: Cambisols are characterized by slight or moderate weathering of parent material and by absence of appreciable quantities of illuviated clay, organic matter, Al and/or Fe compounds. Environment: Level to mountainous terrain in all climates; wide range of vegetation types.
Regional distribution of Cambisols Cambisols cover an estimated 1 500 million ha worldwide. This RSG is particularly well represented in temperate and boreal regions that were under the influence of glaciations during the Pleistocene, partly because the parent material of the soil is still young, but also because soil formation is slow in cool regions. Erosion and deposition cycles explain the occurrence of Cambisols in mountain regions. Cambisols also occur in dry regions but are less common in the humid tropics and subtropics where weathering and soil formation proceed at much faster rates than in temperate, boreal and dry regions. The young alluvial plains and terraces of the Ganges–Brahmaputra system are probably the largest continuous surface of Cambisols in the tropics. Cambisols are also common in areas with active geologic erosion, where they may occur in association with mature tropical soils.
Management and use of Cambisols Cambisols generally make good agricultural land and are used intensively. Cambisols with high base saturation in the temperate zone are among the most productive soils on earth. More acid Cambisols, although less fertile, are used for mixed arable farming and as grazing and forest land. Cambisols on steep slopes are best kept under forest; this is particularly true for Cambisols in highlands. Cambisols on irrigated alluvial plains in the dry zone are used intensively for production of food and oil crops. Cambisols in undulating or hilly terrain (mainly colluvial) are planted to a variety of annual and perennial crops or are used as grazing land. Cambisols in the humid tropics are typically poor in nutrients but are still richer than associated Acrisols or Ferralsols and they have a greater CEC. Cambisols with groundwater influence in alluvial plains are highly productive paddy soils.
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CHERNOZEMS
Chernozems accommodate soils with a thick black surface layer that is rich in organic matter. The Russian soil scientist Dokuchaev coined the name Chernozem in 1883 to denote the typical zonal soil of the tall grass steppes in continental Russia. Many Chernozems correspond to: Calcareous Black Soils and Kalktschernoseme (Germany); Chernosols (France); Eluviated Black Soils (Canada); several suborders (especially Udolls) of the Mollisols (United States of America); and Chernossolos (Brazil).
Summary description of Chernozems Connotation: Black soils rich in organic matter; from Russian chernij, black, and zemlja, earth or land. Parent material: Mostly aeolian and re-washed aeolian sediments (loess). Environment: Regions with a continental climate with cold winters and hot summers, which are dry at least in the late summer; in flat to undulating plains with tall-grass vegetation (forest in the northern transitional zone). Profile development: Dark brown to black mollic surface horizon, in many cases over a cambic or argic subsurface horizon; with secondary carbonates or a calcic horizon in the subsoil.
Regional distribution of Chernozems Chernozems cover an estimated 230 million ha worldwide, mainly in the middle latitude steppes of Eurasia and North America, north of the zone with Kastanozems.
Management and use of Chernozems Russian soil scientists rank the deep, central Chernozems among the best soils in the world. With less than half of all Chernozems in Eurasia being used for arable cropping, these soils constitute a formidable resource for the future. Preservation of the favourable soil structure through timely cultivation and careful irrigation at low watering rates prevents ablation and erosion. Application of P fertilizers is required for high yields. Wheat, barley and maize are the principal crops grown, alongside other food crops and vegetables. Part of the Chernozem area is used for livestock rearing. In the northern temperate belt, the possible growing period is short and the principal crops grown are wheat and barley, in places in rotation with vegetables. Maize is widely grown in the warm temperate belt. Maize production tends to stagnate in drier years unless the crop is irrigated adequately.
CRYOSOLS
Cryosols comprise mineral soils formed in a permafrost environment. Where water is present, it occurs primarily in the form of ice. Cryogenic processes are the dominant soil-forming processes. Cryosols are widely known as permafrost soils. Other common names for many Cryosols are: Gelisols (United States of America), Cryozems (Russian Federation), Cryomorphic soils and Polar desert soils.
Summary description of Cryosols Connotation: Frost-affected soils; from Greek kryos, cold. Parent material: A wide variety of materials, including glacial till and aeolian, alluvial, colluvial and residual materials. Environment: Flat to mountainous areas in Antarctic, Arctic, subarctic and boreal regions affected by permafrost, notably in depressions. Cryosols are associated with sparsely to continuously vegetated tundra, open-canopy lichen coniferous forest and closed-canopy coniferous or mixed coniferous and deciduous forest. 278 Chapter 4 – Description, distribution, use and management of reference soil groups 77
Profile development: In the presence of water, cryogenic processes produce cryoturbated horizons, frost heave, thermal cracking, ice segregation and patterned ground microrelief.
Regional distribution of Cryosols Geographically, Cryosols are circumpolar in both the Northern and Southern Hemispheres. They cover an estimated 180 million km2, or about 13 percent of the global land surface. Cryosols occur in the permafrost regions of the Arctic, and are widespread in the subarctic zone, discontinuous in the boreal zone, and sporadic in more temperate mountainous regions. Major areas with Cryosols are found in the Russian Federation (100 million ha), Canada (25 million ha), China (19 million ha), Alaska (11 million ha), and in parts of Mongolia. Smaller occurrences have been reported from northern Europe, Greenland and the ice-free areas of Antarctica.
Management and use of Cryosols Natural and human-induced biological activity in Cryosols is confined to the active surface layer that thaws every summer and also protects the underlying permafrost. Removal of the peat layer on top of the soil or of the vegetation and/or disturbance of the surface soil often lead to alterations of the permafrost depth and to rapid and drastic environmental changes, with possible damage to structures created by humans. Most areas of Cryosols in North America and Eurasia are in the natural state and support sufficient vegetation for grazing animals, such as caribou, reindeer and musk oxen. Large herds of caribou still migrate seasonally in the northern part of North America; reindeer herding is an important industry in the vast northern areas, especially in northern Europe. Overgrazing leads rapidly to erosion and other environmental damage. Human activities, mainly relating to agriculture, oil and gas production, and mining, have had a major impact on these soils. Severe thermokarsting has occurred on land cleared for agriculture. Improper management of pipelines and mining can cause oil spills and chemical pollution that affect large areas.
DURISOLS
Durisols are associated mainly with old surfaces in arid and semi-arid environments and accommodate very shallow to moderately deep, moderately well- to well-drained soils that contain cemented secondary silica (SiO2) within 100 cm of the soil surface. Many Durisols are known as: hardpan soils (Australia), dorbank (South Africa), Durids (United States of America), or as duripan phase of other soils, e.g. of Calcisols (FAO).
Summary description of Durisols Connotation: Soils with hardened secondary silica; from Latin durus, hard. Parent material: Silicate-rich materials, mainly alluvial and colluvial deposits of all texture classes. Environment: Level and slightly sloping alluvial plains, terraces and gently sloping piedmont plains in arid, semi-arid and Mediterranean regions. Profile development: Strongly weathered soils with a hard layer of secondary silica (petroduric horizon); eroded Durisols with exposed petroduric horizons are common in gently sloping terrain.
Regional distribution of Durisols Extensive areas of Durisols occur in Australia, in South Africa and Namibia, and in the United States of America (notably, Nevada, California and Arizona); minor occurrences have been reported from Central and South America and from Kuwait. Durisols are a 279 78 World reference base for soil resources 2006
relatively new introduction in international soil classification and have not often been mapped as such. A precise indication of their extent is not yet available.
Land use and management of Durisols The agricultural use of Durisols is limited to extensive grazing (rangeland). Durisols in natural environments generally support enough vegetation to contain erosion, but elsewhere erosion of the surface soil is widespread. Stable landscapes occur in dry regions where Durisols were eroded down to their resistant duripan. Durisols may be cultivated with some success where sufficient irrigation water is available. A petroduric horizon may need to be broken up or removed altogether if it forms a barrier to root and water penetration. Excess levels of soluble salts may affect Durisols in low-lying areas. Hard duripan material is widely used in road construction.
FERRALSOLS
Ferralsols represent the classical, deeply weathered, red or yellow soils of the humid tropics. These soils have diffuse horizon boundaries, a clay assemblage dominated by low-activity clays (mainly kaolinite) and a high content of sesquioxides. Local names usually refer to the colour of the soil. Many Ferralsols are known as: Oxisols (United States of America); Latossolos (Brazil); Alítico, Ferrítico and Ferralítico (Cuba); Sols ferralitiques (France); and Ferralitic soils (Russian Federation).
Summary description of Ferralsols Connotation: Red and yellow tropical soils with a high content of sesquioxides; from Latin ferrum, iron, and alumen, alum. Parent material: Strongly weathered material on old, stable geomorphic surfaces; more commonly in material weathered from basic rock than from siliceous material. Environment: Typically in level to undulating land of Pleistocene age or older; less common on younger, easily weathering rocks. Perhumid or humid tropics; minor occurrences elsewhere are considered to be relics from past eras with a warmer and wetter climate than today. Profile development: Deep and intensive weathering has resulted in a residual concentration of resistant primary minerals (e.g. quartz) alongside sesquioxides and kaolinite. This mineralogy and the relatively low pH explain the stable microstructure (pseudo-sand) and yellowish (goethite) or reddish (hematite) soil colours.
Regional distribution of Ferralsols The worldwide extent of Ferralsols is estimated at some 750 million ha, almost exclusively in the humid tropics on the continental shields of South America (especially Brazil) and Africa (especially Congo, Democratic Republic of the Congo, southern Central African Republic, Angola, Guinea and eastern Madagascar). Outside the continental shields, Ferralsols are restricted to regions with easily weathering basic rock and a hot and humid climate, e.g. in Southeast Asia.
Management and use of Ferralsols Most Ferralsols have good physical properties. Great soil depth, good permeability and stable microstructure make Ferralsols less susceptible to erosion than most other intensely weathered tropical soils. Moist Ferralsols are friable and easy to work. They are well drained but may in times be droughty because of their low available water storage capacity. The chemical fertility of Ferralsols is poor; weatherable minerals are scarce or absent, and cation retention by the mineral soil fraction is weak. Under natural 280 Chapter 4 – Description, distribution, use and management of reference soil groups 79
vegetation, nutrient elements that are taken up by the roots are eventually returned to the surface soil with falling leaves and other plant debris. The bulk of all cycling plant nutrients is contained in the biomass; available plant nutrients in the soil are concentrated in the soil organic matter. If the process of nutrient cycling is interrupted, e.g. upon introduction of low-input sedentary subsistence farming, the rootzone will rapidly become depleted of plant nutrients. Maintaining soil fertility by manuring, mulching and/or adequate (i.e. long enough) fallow periods or agroforestry practices, and prevention of surface soil erosion are important management requirements. Strong retention (fixing) of P is a characteristic problem of Ferralsols (and several other soils, e.g. Andosols). Ferralsols are normally also low in N, K, secondary nutrients (Ca, Mg and S), and some 20 micronutrients. Silica deficiency is possible where silica- demanding crops (e.g. grasses) are grown. In Mauritius, soils are tested for available silica and fertilized with silica amendments. Manganese and Zn, which are very soluble at low pH, may at some time reach toxic levels in the soil or become deficient after intense leaching of the soil. Boron and copper deficiencies may also be encountered. Liming is a means of raising the pH value of the rooted surface soil. Liming combats Al toxicity and raises the ECEC. On the other hand, it lowers the anion exchange capacity, which might lead to collapse of structure elements and slaking at the soil surface. Therefore, frequent small doses of lime or basic slag are preferable to one massive application; 0.5–2 tonnes/ha of lime or dolomite are normally enough to supply Ca as a nutrient and to buffer the low soil pH of many Ferralsols. Surface application of gypsum, as a suitably mobile form of Ca, can increase the depth of crop root development (in addition, the sulphate in the gypsum reacts with sesquioxides to produce a “self-liming” effect). This relatively recent innovation is now practised widely, especially in Brazil. Fertilizer selection and the mode and timing of fertilizer application determine to a great extent the success of agriculture on Ferralsols. Slow-release phosphate (phosphate rock) applied at a rate of several tonnes per hectare eliminates P deficiency for a number of years. For a quick fix, much more soluble double or triple superphosphate is used, needed in much smaller quantities, especially if placed in the direct vicinity of the roots. The phosphate rock option is probably only viable economically where it is locally available and when other P fertilizers are not easily purchased. Sedentary subsistence farmers and shifting cultivators on Ferralsols grow a variety of annual and perennial crops. Extensive grazing is also common and considerable areas of Ferralsols are not used for agriculture at all. The good physical properties of Ferralsols and the often level topography would encourage more intensive forms of land use if problems caused by poor chemical properties could be overcome.
FLUVISOLS
Fluvisols accommodate genetically young, azonal soils in alluvial deposits. The name Fluvisols may be misleading in the sense that these soils are not confined only to river sediments (Latin fluvius, river); they also occur in lacustrine and marine deposits. Many Fluvisols correlate with: Alluvial soils (Russian Federation); Hydrosols (Australia); Fluvents and Fluvaquents (United States of America); Auenböden, Marschen, Strandböden, Watten and Unterwasserböden (Germany); Neossolos (Brazil); and Sols minéraux bruts d’apport alluvial ou colluvial or Sols peu évolués non climatiques d’apport alluvial ou colluvial (France).
Summary description of Fluvisols Connotation: Soils developed in alluvial deposits; from Latin fluvius, river. Parent material: Predominantly recent, fluvial, lacustrine and marine deposits. 281 80 World reference base for soil resources 2006
Environment: Alluvial plains, river fans, valleys and tidal marshes on all continents and in all climate zones; many Fluvisols under natural conditions are flooded periodically. Profile development: Profiles with evidence of stratification; weak horizon differentiation but a distinct topsoil horizon may be present. Redoximorphic features are common, in particular in the lower part of the profile.
Regional distribution of Fluvisols Fluvisols occur on all continents and in all climates. They occupy some 350 million ha worldwide, of which more than half are in the tropics. Major concentrations of Fluvisols are found: ÿ along rivers and lakes, e.g. in the Amazon basin, the Ganges Plain of India, the plains near Lake Chad in Central Africa, and the marshlands of Brazil, Paraguay and northern Argentina; ÿ in deltaic areas, e.g. the deltas of the Ganges–Brahmaputra, Indus, Mekong, Mississippi, Nile, Niger, Orinoco, Plate, Po, Rhine and Zambezi; ÿ in areas of recent marine deposits, e.g. the coastal lowlands of Sumatra, Kalimantan and Irian (Indonesia and Papua New Guinea). Major areas of Fluvisols with a thionic horizon or sulphidic material (Acid Sulphate Soils) are found in the coastal lowlands of Southeast Asia (Indonesia, Viet Nam and Thailand), West Africa (Senegal, Gambia, Guinea Bissau, Sierra Leone and Liberia) and along the northeast coast of South America (French Guiana, Guyana, Suriname and Venezuela).
Management and use of Fluvisols The good natural fertility of most Fluvisols and attractive dwelling sites on river levees and on higher parts in marine landscapes were recognized in prehistoric times. Later, great civilizations developed in river landscapes and on marine plains. Paddy rice cultivation is widespread on tropical Fluvisols with satisfactory irrigation and drainage. Paddy land should be dry for at least a few weeks every year in order to prevent the redox potential of the soil from becoming so low that nutritional problems
(Fe or H2S) arise. A dry period also stimulates microbial activity and promotes mineralization of organic matter. Many dryland crops are grown on Fluvisols as well, normally with some form of water control. Tidal lands that are strongly saline are best kept under mangroves or some other salt-tolerant vegetation. Such areas are ecologically valuable and can, with caution, be used for fishing, hunting, salt pans or woodcutting for charcoal or fuelwood. Fluvisols with a thionic horizon or sulphidic material suffer from severe acidity and high levels of Al toxicity.
GLEYSOLS
Gleysols are wetland soils that, unless drained, are saturated with groundwater for long enough periods to develop a characteristic gleyic colour pattern. This pattern is essentially made up of reddish, brownish or yellowish colours at ped surfaces and/or in the upper soil layer or layers, in combination with greyish/bluish colours inside the peds and/or deeper in the soil. Common names for many Gleysols are: gley and meadow soils (former Soviet Union); Gleyzems (Russian Federation); Gleye (Germany); Gleissolos (Brazil); and groundwater soils. Many of the WRB Gleysols correlate with the aquic suborders of the US Soil Taxonomy (Aqualfs, Aquents, Aquepts, Aquolls, etc).
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Summary description of Gleysols Connotation: Soils with clear signs of groundwater influence; from Russian gley, mucky mass. Parent material: A wide range of unconsolidated materials, mainly fluvial, marine and lacustrine sediments of Pleistocene or Holocene age, with basic to acidic mineralogy. Environment: Depression areas and low landscape positions with shallow groundwater. Profile development: Evidence of reduction processes with segregation of Fe compounds within 50 cm of the soil surface.
Regional distribution of Gleysols Gleysols occupy an estimated 720 million ha worldwide. They are azonal soils and occur in nearly all climates, from perhumid to arid. The largest extent of Gleysols is in subarctic areas in the north of the Russian Federation (especially Siberia), Canada and Alaska, and in humid temperate and subtropical lowlands, e.g. in China and Bangladesh. An estimated 200 million ha of Gleysols are found in the tropics, mainly in the Amazon region, equatorial Africa, and the coastal swamps of Southeast Asia.
Management and use of Gleysols The main obstacle to utilization of Gleysols is the necessity to install a drainage system to lower the groundwater table. Adequately drained Gleysols can be used for arable cropping, dairy farming and horticulture. Soil structure will be destroyed for a long time if soils are cultivated when too wet. Therefore, Gleysols in depression areas with unsatisfactory possibilities to lower the groundwater table are best kept under a permanent grass cover or swamp forest. Liming of drained Gleysols that are high in organic matter and/or of low pH value creates a better habitat for micro- and meso- organisms and enhances the rate of decomposition of soil organic matter (and the supply of plant nutrients). Gleysols can be put under tree crops only after the water table has been lowered with deep drainage ditches. Alternatively, the trees are planted on ridges that alternate with shallow depressions in which rice is grown. This sorjan system is applied widely in tidal swamp areas with pyritic sediments in Southeast Asia. Gleysols can be well used for wetland rice cultivation where the climate is appropriate. Gleysols with a thionic horizon or sulphidic material suffer from severe acidity and high levels of Al toxicity.
GYPSISOLS
Gypsisols are soils with substantial secondary accumulation of gypsum (CaSO4.2H2O). These soils are found in the driest parts of the arid climate zone, which explains why leading soil classification systems labelled many of them Desert soils (former Soviet Union), and Yermosols or Xerosols (FAO–UNESCO, 1971–1981). The US Soil Taxonomy terms most of them Gypsids.
Summary description of Gypsisols Connotation: Soils with substantial accumulation of secondary calcium sulphate; from Greek gypsos, gypsum. Parent material: Mostly unconsolidated alluvial, colluvial or aeolian deposits of base-rich weathering material. Environment: Predominantly level to hilly land and depression areas (e.g. former inland lakes) in regions with an arid climate. The natural vegetation is sparse and dominated by xerophytic shrubs and trees and/or ephemeral grasses.
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Profile development: Light-coloured surface horizon; accumulation of calcium sulphate, with or without carbonates, is concentrated in the subsoil.
Regional distribution of Gypsisols Gypsisols are exclusive to arid regions; their worldwide extent is probably of the order of 100 million ha. Major occurrences are in and around Mesopotamia, in desert areas in the Near East and adjacent Central Asian republics, in the Libyan and Namib deserts, in southeast and central Australia and in the southwest of the United States of America.
Management and use of Gypsisols Gypsisols that contain only a low percentage of gypsum in the upper 30 cm can be used for the production of small grains, cotton, alfalfa, etc. Dry farming on deep Gypsisols makes use of fallow years and other water harvesting techniques but is rarely very rewarding because of the adverse climate conditions. Gypsisols in young alluvial and colluvial deposits have a relatively low gypsum content. Where such soils are in the vicinity of water resources, they can be very productive; many irrigation projects are established on such soils. However, even soils containing 25 percent powdery gypsum or more could still produce excellent yields of alfalfa hay (10 tonnes/ha), wheat, apricots, dates, maize and grapes if irrigated at high rates in combination with forced drainage. Irrigated agriculture on Gypsisols is plagued by rapid dissolution of soil gypsum, resulting in irregular subsidence of the land surface, caving in canal walls, and corrosion of concrete structures. Large areas with Gypsisols are in use for extensive grazing.
HISTOSOLS
Histosols comprise soils formed in organic material. These vary from soils developed in predominantly moss peat in boreal, arctic and subarctic regions, via moss peat, reeds/ sedge peat (fen) and forest peat in temperate regions to mangrove peat and swamp forest peat in the humid tropics. Histosols are found at all altitudes, but the vast majority occurs in lowlands. Common names are peat soils, muck soils, bog soils and organic soils. Many Histosols belong to: Moore, Felshumusböden and Skeletthumusböden (Germany); Organosols (Australia); Organossolos (Brazil); Organic order (Canada); and Histosols and Histels (United States of America).
Summary description of Histosols Connotation: Peat and muck soils; from Greek histos, tissue. Parent material: Incompletely decomposed plant remains, with or without admixtures of sand, silt or clay. Environment: Histosols occur extensively in boreal, arctic and subarctic regions. Elsewhere, they are confined to poorly drained basins and depressions, swamp and marshlands with shallow groundwater, and highland areas with a high precipitation– evapotranspiration ratio. Profile development: Mineralization is slow and transformation of plant remains through biochemical disintegration, and formation of humic substances creates a surface layer of mould with or without prolonged water saturation. Translocated organic material may accumulate in deeper tiers but is more often leached from the soil.
Regional distribution of Histosols The total extent of Histosols in the world is estimated at some 325–375 million ha, the majority located in the boreal, subarctic and low arctic regions of the Northern Hemisphere. Most of the remaining Histosols occur in temperate lowlands and cool montane areas; only one-tenth of all Histosols are found in the tropics. Extensive areas 284 Chapter 4 – Description, distribution, use and management of reference soil groups 83
of Histosols occur in the United States of America and Canada, western Europe and northern Scandinavia, and in northern regions east of the Ural mountain range. Some 20 million ha of tropical forest peat border the Sunda shelf in Southeast Asia. Smaller areas of tropical Histosols are found in river deltas, e.g. in the Orinoco Delta and the delta of the River Mekong, and in depression areas at some altitude.
Management and use of Histosols The properties of the organic material (botanical composition, stratification, degree of decomposition, packing density, wood content, mineral admixtures, etc.) and the type of peat bog (basin peat [fen], raised bog, etc.) determine the management requirements and use possibilities of Histosols. Histosols without prolonged water saturation are often formed in cold environments unattractive for agricultural use. Natural peats need to be drained and, normally, also limed and fertilized in order to permit cultivation of normal crops. Centrally guided reclamation projects are almost exclusive to the temperate zone, where millions of hectares have been opened. In many instances, this has initiated the gradual degradation, and ultimately the loss, of the precious peat. In the tropics, increasing numbers of landless farmers venture onto the peat lands, where they clear the forest and cause raging peat fires in the process. Many of them abandon their land again after only a few years; the few that succeed are on shallow, topogenous peat. In recent decades, increasing areas of tropical peat land have been planted to oil-palm and pulp wood tree species such as Acacia mangium, Acacia crassicarpa and Eucalyptus sp. This practice may be less than ideal but it is far less destructive than arable subsistence farming. Another common problem encountered when Histosols are drained is the oxidation of sulphidic minerals, which accumulate under anaerobic conditions, especially in coastal regions. The sulphuric acid produced effectively destroys productivity unless lime is applied copiously, making the cost of reclamation prohibitive. In summary, it is desirable to protect and conserve fragile peat lands because of their intrinsic value (especially their common function as sponges in regulating stream flow and in supporting wetlands containing unique species of animals) and because prospects for their sustained agricultural use are meagre. Where their use is imperative, sensible forms of forestry or plantation cropping are to be preferred over annual cropping, horticulture or, the worst option, harvesting of the peat material for power generation or production of horticultural growth substrate, active carbon, flower pots, etc. Peat that is used for arable crop production will mineralize at sharply increased rates because it must be drained, limed and fertilized in order to ensure satisfactory crop growth. Under these circumstances, the drain depth should be kept as shallow as possible and prudence exercised when applying lime and fertilizers.
KASTANOZEMS
Kastanozems accommodate dry grassland soils, among them the zonal soils of the short-grass steppe belt, south of the Eurasian tall-grass steppe belt with Chernozems. Kastanozems have a similar profile to that of Chernozems but the humus-rich surface horizon is thinner and not as dark as that of the Chernozems and they show more prominent accumulation of secondary carbonates. The chestnut-brown colour of the surface soil is reflected in the name Kastanozem; common names for many Kastanozems are: (Dark) Chestnut Soils (Russian Federation), Kalktschernoseme (Germany), (Dark) Brown Soils (Canada), and Ustolls and Xerolls (United States of America).
Summary description of Kastanozems Connotation: Dark brown soils rich in organic matter; from Latin castanea and Russian kashtan, chestnut, and zemlja, earth or land. 285 84 World reference base for soil resources 2006
Parent material: A wide range of unconsolidated materials; a large part of all Kastanozems has developed in loess. Environment: Dry and continental with relatively cold winters and hot summers; flat to undulating grasslands dominated by ephemeral short grasses. Profile development: A brown mollic horizon of medium depth, in many cases over a brown to cinnamon cambic or argic horizon; with secondary carbonates or a calcic horizon in the subsoil, in some cases also with secondary gypsum.
Regional distribution of Kastanozems The total extent of Kastanozems is estimated to be about 465 million ha. Major areas are in the Eurasian short-grass steppe belt (southern Ukraine, the south of the Russian Federation, Kazakhstan and Mongolia), in the Great Plains of the United States of America, Canada and Mexico, and in the pampas and chaco regions of northern Argentina, Paraguay and southern Bolivia.
Management and use of Kastanozems Kastanozems are potentially rich soils; periodic lack of soil moisture is the main obstacle to high yields. Irrigation is nearly always necessary for high yields; care must be taken to avoid secondary salinization of the surface soil. Phosphate fertilizers might be necessary for good yields. Small grains and irrigated food and vegetable crops are the principal crops grown. Wind and water erosion is a problem on Kastanozems, especially on fallow lands. Extensive grazing is another important land use on Kastanozems. However, the sparsely vegetated grazing lands are inferior to the tall-grass steppes on Chernozems, and overgrazing is a serious problem.
LEPTOSOLS
Leptosols are very shallow soils over continuous rock and soils that are extremely gravelly and/or stony. Leptosols are azonal soils and particularly common in mountainous regions. Leptosols include the: Lithosols of the Soil Map of the World (FAO–UNESCO, 1971–1981); Lithic subgroups of the Entisol order (United States of America); Leptic Rudosols and Tenosols (Australia); and Petrozems and Litozems (Russian Federation). In many national systems, Leptosols on calcareous rocks belong to Rendzinas, and those on other rocks to Rankers. Continuous rock at the surface is considered non-soil in many soil classification systems.
Summary description of Leptosols Connotation: Shallow soils; from Greek leptos, thin. Parent material: Various kinds of continuous rock or of unconsolidated materials with less than 20 percent (by volume) fine earth. Environment: Mostly land at high or medium altitude and with strongly dissected topography. Leptosols are found in all climate zones (many of them in hot or cold dry regions), in particular in strongly eroding areas. Profile development: Leptosols have continuous rock at or very close to the surface or are extremely gravelly. Leptosols in calcareous weathering material may have a mollic horizon.
Regional distribution of Leptosols Leptosols are the most extensive RSG on earth, extending over about 1 655 million ha. Leptosols are found from the tropics to the cold polar tundra and from sea level to the highest mountains. Leptosols are particularly widespread in montane areas, notably in Asia and South America, in the Sahara and the Arabian deserts, the Ungava Peninsula 286 Chapter 4 – Description, distribution, use and management of reference soil groups 85
of northern Canada and in the Alaskan mountains. Elsewhere, Leptosols can be found on rocks that are resistant to weathering or where erosion has kept pace with soil formation, or has removed the top of the soil profile. Leptosols with continuous rock at less than 10 cm depth in montane regions are the most extensive Leptosols.
Management and use of Leptosols Leptosols have a resource potential for wet-season grazing and as forest land. Leptosols to which the rendzic qualifier applies are planted to teak and mahogany in Southeast Asia; those in the temperate zone are under mainly deciduous mixed forest whereas acid Leptosols are commonly under coniferous forest. Erosion is the greatest threat to Leptosol areas, particularly in montane regions in the temperate zones where high population pressure (tourism), overexploitation and increasing environmental pollution lead to deterioration of forests and threaten large areas of vulnerable Leptosols. Leptosols on hill slopes are generally more fertile than their counterparts on more level land. One or a few good crops could perhaps be grown on such slopes but at the price of severe erosion. Steep slopes with shallow and stony soils can be transformed into cultivable land through terracing, the removal of stones by hand and their use as terrace fronts. Agroforestry (a combination of rotation of arable crops and forest under strict control) holds promise but is still largely in an experimental stage. The excessive internal drainage and the shallowness of many Leptosols can cause drought even in a humid environment.
LIXISOLS
Lixisols comprise soils that have a higher clay content in the subsoil than in the topsoil as a result of pedogenetic processes (especially clay migration) leading to an argic subsoil horizon. Lixisols have a high base saturation and low-activity clays at certain depths. Many Lixisols are included in: Red Yellow Podzolic soils (e.g. Indonesia); Argissolos (Brazil); sols ferralitiques faiblement desaturés appauvris (France); and Red and Yellow Earths, Latosols or Alfisols with low-activity clays (United States of America).
Summary description of Lixisols Connotation: Soils with a pedogenetic clay differentiation (especially clay migration) between a topsoil with a lower and a subsoil with a higher clay content, low-activity clays and a high base saturation at some depths; from Latin lixivia, washed-out substances. Parent material: In a wide variety of parent materials, notably in unconsolidated, strongly weathered and strongly leached, finely textured materials. Environment: Regions with a tropical, subtropical or warm temperate climate with a pronounced dry season, notably on old erosion or deposition surfaces. Many Lixisols are surmised to be polygenetic soils with characteristics formed under a more humid climate in the past.
Regional distribution of Lixisols Lixisols are found in seasonally dry tropical, subtropical and warm temperate regions on Pleistocene and older surfaces. These soils cover a total area of about 435 million ha, of which more than half occur in sub-Sahelian and East Africa, about one-quarter in South and Central America, and the remainder on the Indian subcontinent and in Southeast Asia and Australia.
Management and use of Lixisols Areas with Lixisols that are still under natural savannah or open woodland vegetation are widely used for low volume grazing. Preservation of the surface soil with its all- 287 86 World reference base for soil resources 2006
important organic matter is of utmost importance. Degraded surface soils have low aggregate stability and are prone to slaking and/or erosion where exposed to the direct impact of raindrops. Tillage of wet soil or use of excessively heavy machinery compacts the soil and causes serious structure deterioration. Tillage and erosion control measures such as terracing, contour ploughing, mulching and use of cover crops help to conserve the soil. The low absolute level of plant nutrients and the low cation retention by Lixisols makes recurrent inputs of fertilizers and/or lime a precondition for continuous cultivation. Chemically and/or physically deteriorated Lixisols regenerate very slowly where not reclaimed actively. Perennial crops are to be preferred to annual crops, particularly on sloping land. Cultivation of tuber crops (cassava and sweet potato) or groundnut increases the danger of soil deterioration and erosion. Rotation of annual crops with improved pasture has been recommended in order to maintain or improve the content of soil organic matter.
LUVISOLS
Luvisols are soils that have a higher clay content in the subsoil than in the topsoil as a result of pedogenetic processes (especially clay migration) leading to an argic subsoil horizon. Luvisols have high-activity clays throughout the argic horizon and a high base saturation at certain depths. Many Luvisols are or were known as: Textural- metamorphic soils (Russian Federation), sols lessivés (France), Parabraunerden (Germany), Chromosols (Australia), Luvissolos (Brazil), Grey-Brown Podzolic soils (earlier terminology of the United States of America), and Alfisols with high-activity clays (US Soil Taxonomy).
Summary description of Luvisols Connotation: Soils with a pedogenetic clay differentiation (especially clay migration) between a topsoil with a lower and a subsoil with a higher clay content, high-activity clays and a high base saturation at some depth; from Latin luere, to wash. Parent material: A wide variety of unconsolidated materials including glacial till, and aeolian, alluvial and colluvial deposits. Environment: Most common in flat or gently sloping land in cool temperate regions and in warm regions (e.g. Mediterranean) with distinct dry and wet seasons. Profile development: Pedogenetic differentiation of clay content with a lower content in the topsoil and a higher content in the subsoil without marked leaching of base cations or advanced weathering of high-activity clays; highly leached Luvisols might have an albic eluviation horizon between the surface horizon and an argic subsurface horizon, but lack the albeluvic tonguing of Albeluvisols.
Regional distribution of Luvisols Luvisols extend over 500–600 million ha worldwide, mainly in temperate regions such as in the west and centre of the Russian Federation, the United States of America, and Central Europe, but also in the Mediterranean region and southern Australia. In subtropical and tropical regions, Luvisols occur mainly on young land surfaces.
Management and use of Luvisols Most Luvisols are fertile soils and suitable for a wide range of agricultural uses. Luvisols with a high silt content are susceptible to structure deterioration where tilled when wet or with heavy machinery. Luvisols on steep slopes require erosion control measures. The eluvial horizons of some Luvisols are depleted to the extent that an unfavourable platy structure is formed. In places, the dense subsoil causes temporarily reducing 288 Chapter 4 – Description, distribution, use and management of reference soil groups 87
conditions with a stagnic colour pattern. These are the reasons why truncated Luvisols are in many instances better soils for farming than the original, non-eroded soils. Luvisols in the temperate zone are widely grown to small grains, sugar beet and fodder; in sloping areas, they are used for orchards, forests and/or grazing. In the Mediterranean region, where Luvisols (many with the chromic, calcic or vertic qualifier) are common in colluvial deposits of limestone weathering, the lower slopes are widely sown to wheat and/or sugar beet while the often eroded upper slopes are used for extensive grazing or planted to tree crops.
NITISOLS
Nitisols are deep, well-drained, red, tropical soils with diffuse horizon boundaries and a subsurface horizon with more than 30 percent clay and moderate to strong angular blocky structure elements that easily fall apart into characteristic shiny, polyhedric (nutty) elements. Weathering is relatively advanced but Nitisols are far more productive than most other red, tropical soils. Many Nitisols correlate with: Nitossolos (Brazil); kandic Great Groups of Alfisols and Ultisols, and different Great Groups of Inceptisols and Oxisols (United States of America); Sols Fersialitiques or Ferrisols (France); and Red Earths.
Summary description of Nitisols Connotation: Deep, well-drained, red, tropical soils with a clayey nitic subsurface horizon that has typical nutty, polyhedric, blocky structure elements with shiny ped faces; from Latin nitidus, shiny. Parent material: Finely textured weathering products of intermediate to basic parent rock, in some regions rejuvenated by recent admixtures of volcanic ash. Environment: Nitisols are predominantly found in level to hilly land under tropical rain forest or savannah vegetation. Profile development: Red or reddish-brown clayey soils with a nitic subsurface horizon of high aggregate stability. The clay assemblage of Nitisols is dominated by kaolinite/(meta)halloysite. Nitisols are rich in Fe and have little water-dispersible clay.
Regional distribution of Nitisols There are about 200 million ha of Nitisols worldwide. More than half of all Nitisols are found in tropical Africa, notably in the highlands (> 1 000 m) of Ethiopia, Kenya, Congo and Cameroon. Elsewhere, Nitisols are well represented at lower altitudes, e.g. in tropical Asia, South America, Central America, Southeast Africa and Australia.
Management and use of Nitisols Nitisols are among the most productive soils of the humid tropics. The deep and porous solum and the stable soil structure of Nitisols permit deep rooting and make these soils quite resistant to erosion. The good workability of Nitisols, their good internal drainage and fair water holding properties are complemented by chemical (fertility) properties that compare favourably with those of most other tropical soils. Nitisols have relatively high contents of weathering minerals, and surface soils may contain several percent of organic matter, in particular under forest or tree crops. Nitisols are planted to plantation crops such as cocoa, coffee, rubber and pineapple, and are also widely used for food crop production on smallholdings. High P sorption calls for application of P fertilizers, usually provided as slow-release, low-grade phosphate rock (several tonnes per hectare, with maintenance doses every few years) in combination with smaller applications of better soluble superphosphate for short-term response by the crop. 289 88 World reference base for soil resources 2006
PHAEOZEMS
Phaeozems accommodate soils of relatively wet grassland and forest regions in moderately continental climates. Phaeozems are much like Chernozems and Kastanozems but are leached more intensively. Consequently, they have dark, humus- rich surface horizons that, in comparison with Chernozems and Kastanozems, are less rich in bases. Phaeozems may or may not have secondary carbonates but have a high base saturation in the upper metre of the soil. Commonly used names for many Phaeozems are: Brunizems (Argentina and France); Dark grey forest soils and Leached and podzolized chernozems (former Soviet Union); Tschernoseme (Germany); Dusky- red prairie soils (older classification of the United States of America); Udolls and Albolls (US Soil Taxonomy); and Phaeozems (including most of the former Greyzems) (FAO).
Summary description of Phaeozems Connotation: Dark soils rich in organic matter; from Greek phaios, dusky, and Russian zemlja, earth or land. Parent material: Aeolian (loess), glacial till and other unconsolidated, predominantly basic materials. Environment: Warm to cool (e.g. tropical highlands) moderately continental regions, humid enough that there is, in most years, some percolation through the soil, but also with periods in which the soil dries out; flat to undulating land; the natural vegetation is grassland such as tall-grass steppe and/or forest. Profile development: A mollic horizon (thinner and in many soils less dark than in Chernozems), mostly over a cambic or argic subsurface horizon.
Regional distribution of Phaeozems Phaeozems cover an estimated 190 million ha worldwide. Some 70 million ha of Phaeozems are found in the humid and subhumid Central Lowlands and easternmost parts of the Great Plains of the United States of America. Another 50 million ha of Phaeozems are in the subtropical pampas of Argentina and Uruguay. The third largest area of Phaeozems (18 million ha) is in northeast China, followed by extensive areas in the centre of the Russian Federation. Smaller, mostly discontinuous areas are found in Central Europe, notably the Danube area of Hungary and adjacent countries and in montane areas in the tropics.
Management and use of Phaeozems Phaeozems are porous, fertile soils and make excellent farmland. In the United States of America and Argentina, Phaeozems are in use for the production of soybean and wheat (and other small grains). Phaeozems on the high plains of Texas produce good yields of irrigated cotton. Phaeozems in the temperate belt are planted to wheat, barley and vegetables alongside other crops. Wind and water erosion are serious hazards. Vast areas of Phaeozems are used for cattle rearing and fattening on improved pastures.
PLANOSOLS
Planosols are soils with a light-coloured, surface horizon that shows signs of periodic water stagnation and abruptly overlies a dense, slowly permeable subsoil with significantly more clay than the surface horizon. The US Soil Classification coined the name Planosols in 1938; its successor, the US Soil Taxonomy, includes most of the original Planosols in the Great Groups of the Albaqualfs, Albaquults and Argialbolls. The name has been adopted in Brazil (Planossolos).
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Summary description of Planosols Connotation: Soils with a coarse-textured surface horizon abruptly over a dense and finer textured subsoil, typically in seasonally waterlogged flat lands; from Latin planus, flat. Parent material: Mostly clayey alluvial and colluvial deposits. Environment: Seasonally or periodically wet, level (plateau) areas, mainly in subtropical and temperate, semi-arid and subhumid regions with light forest or grass vegetation. Profile development: Geological stratification or pedogenesis (destruction and/or removal of clay), or both, has produced relatively coarse-textured, light-coloured surface soil abruptly overlying finer textured subsoil; impeded downward percolation of water causes temporarily reducing conditions with a stagnic colour pattern, at least close to the abrupt textural change.
Regional distribution of Planosols The world’s major Planosol areas occur in subtropical and temperate regions with clear alternation of wet and dry seasons, e.g. in Latin America (southern Brazil, Paraguay and Argentina), Africa (Sahelian zone, East and Southern Africa), the east of the United States of America, Southeast Asia (Bangladesh and Thailand), and Australia. Their total extent is estimated at some 130 million ha.
Management and use of Planosols Natural Planosol areas support a sparse grass vegetation, often with scattered shrubs and trees that have shallow root systems and can cope with temporary waterlogging. Land use on Planosols is normally less intensive than that on most other soils under the same climate conditions. Vast areas of Planosols are used for extensive grazing. Wood production on Planosols is much lower than on other soils under the same conditions. Planosols in the temperate zone are mainly in grass or they are planted to arable crops such as wheat and sugar beet. Yields are modest even on drained and deeply loosened soils. Root development on natural unmodified Planosols is hindered severely by oxygen deficiency in wet periods, dense subsoil and, in places, by toxic levels of Al in the rootzone. The low hydraulic conductivity of the dense subsurface soil makes narrow drain spacing necessary. Surface modification such as ridge and furrow can lessen crop yield losses from waterlogging. Planosols in Southeast Asia are widely planted to a single crop of paddy rice, produced on bunded fields that are inundated in the rainy season. Efforts to produce dryland crops on the same land during the dry season have met with little success; the soils seem better suited to a second crop of rice with supplemental irrigation. Fertilizers are needed for good yields. Paddy fields should be allowed to dry out at least once a year in order to prevent or minimize microelement deficiencies or toxicity associated with prolonged soil reduction. Some Planosols require application of more than just NPK fertilizers, and their low fertility level may prove difficult to correct. Where temperature permits paddy rice cultivation, this is probably superior to any other kind of land use. Grasslands with supplemental irrigation in the dry season are a good land use in climates with long dry periods and short infrequent wet spells. Strongly developed Planosols with a very silty or sandy surface soil are perhaps best left untouched.
PLINTHOSOLS
Plinthosols are soils with plinthite, petroplinthite or pisoliths. Plinthite is an Fe-rich (in some cases also Mn-rich), humus-poor mixture of kaolinitic clay (and other products 291 90 World reference base for soil resources 2006
of strong weathering such as gibbsite) with quartz and other constituents that changes irreversibly to a layer with hard nodules, a hardpan or irregular aggregates on exposure to repeated wetting and drying. Petroplinthite is a continuous, fractured or broken sheet of connected, strongly cemented to indurated nodules or mottles. Pisoliths are discrete strongly cemented to indurated nodules. Both petroplinthite and pisoliths develop from plinthite by hardening. Many of these soils are known as: Groundwater Laterite Soils, Perched Water Laterite Soils and Plintossolos (Brazil); Sols gris latéritiques (France); and Plinthaquox, Plinthaqualfs, Plinthoxeralfs, Plinthustalfs, Plinthaquults, Plinthohumults, Plinthudults and Plinthustults (United States of America).
Summary description of Plinthosols Connotation: Soils with plinthite, petroplinthite or pisoliths; from Greek plinthos, brick. Parent material: Plinthite is more common in weathering material from basic rock than in acidic rock weathering. In any case, it is crucial that sufficient Fe be present, originating either from the parent material itself or brought in by seepage water or ascending groundwater from elsewhere. Environment: Formation of plinthite is associated with level to gently sloping areas with fluctuating groundwater or stagnating surface water. A widely held view is that plinthite is associated with rain forest areas whereas petroplinthic and pisolithic soils are more common in the savannah zone. Profile development: Strong weathering with subsequent segregation of plinthite at the depth of groundwater fluctuation or impeded surface water drainage. Hardening of plinthite to pisoliths or petroplinthite takes place upon repeated drying and wetting. This may occur during the intervals of recession of a seasonally fluctuating water table or after geological uplift of the terrain, topsoil erosion, lowering of the groundwater level, increasing drainage capacity, and/or climate change towards drier conditions. Petroplinthite may break up into irregular aggregates or gravels, which may be transported to form colluvial or alluvial deposits. Hardening or induration requires a certain minimum concentration of iron oxides.
Regional distribution of Plinthosols The global extent of Plinthosols is estimated at some 60 million ha. Soft plinthite is most common in the wet tropics, notably in the eastern Amazon basin, the central Congo basin and parts of Southeast Asia. Extensive areas with pisoliths and petroplinthite occur in the Sudano-Sahelian zone, where petroplinthite forms hard caps on top of uplifted/exposed landscape elements. Similar soils occur in the Southern African savannah, on the Indian subcontinent, and in drier parts of Southeast Asia and northern Australia.
Management and use of Plinthosols Plinthosols present considerable management problems. Poor natural soil fertility caused by strong weathering, waterlogging in bottomlands and drought on Plinthosols with petroplinthite, pisoliths or gravels are serious limitations. Many Plinthosols outside of the wet tropics have shallow, continuous petroplinthite, which limits the rooting volume to the extent that arable farming is not possible; such land can at best be used for low-volume grazing. Soils with high contents of pisoliths (up to 80 percent) are still planted to food crops and tree crops (e.g. cocoa in West Africa, and cashew in India) but the crops suffer from drought in the dry season. Many soil and water conservation techniques are used to improve these soils for urban and peri-urban agriculture in West Africa. Civil engineers have a different appreciation of petroplinthite and plinthite than do agronomists. To them, plinthite is a valuable material for making bricks, and massive 292 Chapter 4 – Description, distribution, use and management of reference soil groups 91
petroplinthite is a stable surface for building or it can be cut to building blocks. Gravels of broken petroplinthite can be used in foundations and as surfacing material on roads and airfields. In some instances, petroplinthite is a valuable ore of Fe, Al, Mn and/or Ti.
PODZOLS
Podzols are soils with a typically ash-grey upper subsurface horizon, bleached by loss of organic matter and iron oxides, on top of a dark accumulation horizon with brown, reddish or black illuviated humus and/or reddish Fe compounds. Podzols occur in humid areas in the boreal and temperate zones and locally also in the tropics. The name Podzol is used in most national soil classification systems; other names for many of these soils are: Spodosols (China and United States of America), Espodossolos (Brazil), and Podosols (Australia).
Summary description of Podzols Connotation: Soils with a spodic illuviation horizon under a subsurface horizon that has the appearance of ash and is covered by an organic layer; from Russian pod, underneath, and zola, ash. Parent material: Weathering materials of siliceous rock, including glacial till and alluvial and aeolian deposits of quartzite sands. Podzols in the boreal zone occur on almost any rock. Environment: Mainly in humid temperate and boreal regions of the Northern Hemisphere, in level to hilly land under heather and/or coniferous forest; in the humid tropics under light forest. Profile development: Complexes of Al, Fe and organic compounds migrate from the surface soil downwards with percolating rainwater. The metal–humus complexes precipitate in an illuvial spodic horizon; the overlying eluvial horizon remains bleached and is in many Podzols an albic horizon. This is covered by an organic layer whereas dark mineral topsoil horizons are absent in most boreal Podzols.
Regional distribution of Podzols Podzols cover an estimated 485 million ha worldwide, mainly in the temperate and boreal regions of the Northern Hemisphere. They are extensive in Scandinavia, the northwest of the Russian Federation, and Canada. Besides these zonal Podzols, there are smaller occurrences of intrazonal Podzols in both the temperate zone and the tropics. Tropical Podzols occur on less than 10 million ha, mainly in residual sandstone weathering in perhumid regions and in alluvial quartz sands, e.g. in uplifted coastal areas. The exact distribution of tropical Podzols is not known; important occurrences are found along the Rio Negro and in French Guiana, Guyana and Suriname in South America, in the Malaysian region (Kalimantan, Sumatra and Irian), and in northern and southern Australia. They seem to be less common in Africa.
Management and use of Podzols Zonal Podzols occur in regions with unattractive climate conditions for most arable land uses. Intrazonal Podzols are more frequently reclaimed for arable use than are zonal Podzols, particularly those in temperate climates. The low nutrient status, low level of available moisture and low pH make Podzols unattractive soils for arable farming. Aluminium toxicity and P deficiency are common problems. Deep ploughing (to improve the moisture storage capacity of the soil and/or to eliminate a dense illuviation horizon or hardpan), liming and fertilization are the main ameliorative measures taken. Trace elements may migrate with the metal–humus complexes. In the 293 92 World reference base for soil resources 2006
Western Cape region of South Africa, deeper rooted orchards and vineyards suffer fewer trace element deficiencies than do shallow-rooted vegetable crops. Most zonal Podzols are under forest; intrazonal Podzols in temperate regions are mostly under forest or shrubs (heath). Tropical Podzols normally sustain a light forest that recovers only slowly after cutting or burning. Mature Podzols are generally best used for extensive grazing or left idle under their natural (climax) vegetation.
REGOSOLS
Regosols form a taxonomic remnant group containing all soils that could not be accommodated in any of the other RSGs. In practice, Regosols are very weakly developed mineral soils in unconsolidated materials that do not have a mollic or umbric horizon, are not very shallow or very rich in gravels (Leptosols), sandy (Arenosols) or with fluvic materials (Fluvisols). Regosols are extensive in eroding lands, particularly in arid and semi-arid areas and in mountainous terrain. Many Regosols correlate with soil taxa that are marked by incipient soil formation such as: Entisols (United States of America); Rudosols (Australia); Regosole (Germany); Sols peu évolués régosoliques d’érosion or even Sols minéraux bruts d’apport éolien ou volcanique (France); and Neossolos (Brazil).
Summary description of Regosols Connotation: Weakly developed soils in unconsolidated material; from Greek rhegos, blanket. Parent material: unconsolidated, finely grained material. Environment: All climate zones without permafrost and at all elevations. Regosols are particularly common in arid areas (including the dry tropics) and in mountain regions. Profile development: No diagnostic horizons. Profile development is minimal as a consequence of young age and/or slow soil formation, e.g. because of aridity. Regional distribution of Regosols Regosols cover an estimated 260 million ha worldwide, mainly in arid areas in the mid-west of the United States of America, northern Africa, the Near East, and Australia. Some 50 million ha of Regosols occur in the dry tropics and another 36 million ha in mountain areas. The extent of most Regosol areas is only limited; consequently, Regosols are common inclusions in other map units on small-scale maps.
Management and use of Regosols Regosols in desert areas have minimal agricultural significance. Regosols with rainfall of 500–1 000 mm/year need irrigation for satisfactory crop production. The low moisture holding capacity of these soils calls for frequent applications of irrigation water; sprinkler or trickle irrigation solves the problem but is rarely economic. Where rainfall exceeds 750 mm/year, the entire profile is raised to its water holding capacity early in the wet season; improvement of dry farming practices may then be a better investment than installation of costly irrigation facilities. Many Regosols are used for extensive grazing. Regosols on colluvial deposits in the loess belt of northern Europe and North America are mostly cultivated; they are planted to small grains, sugar beet and fruit trees. Regosols in mountainous regions are delicate and best left under forest.
SOLONCHAKS
Solonchaks are soils that have a high concentration of soluble salts at some time in the year. Solonchaks are largely confined to the arid and semi-arid climate zones and 294 Chapter 4 – Description, distribution, use and management of reference soil groups 93
to coastal regions in all climates. Common international names are saline soils and salt-affected soils. In national soil classification systems, many Solonchaks belong to: halomorphic soils (Russian Federation), Halosols (China), and Salids (United States of America).
Summary description of Solonchaks Connotation: Saline soils; from Russian sol, salt. Parent material: Virtually any unconsolidated material. Environment: Arid and semi-arid regions, notably in areas where ascending groundwater reaches the solum, with vegetation of grasses and/or halophytic herbs, and in inadequately managed irrigation areas. Solonchaks in coastal areas occur in all climates. Profile development: From weakly to strongly weathered, many Solonchaks have a gleyic colour pattern at some depth. In low-lying areas with a shallow water table, salt accumulation is strongest at the soil surface of the soil (external Solonchaks). Solonchaks where ascending groundwater does not reach the topsoil (or even the solum) have the greatest accumulation of salts at some depth below the soil surface (internal Solonchaks).
Regional distribution of Solonchaks The total extent of Solonchaks in the world is estimated at about 260 million ha. Solonchaks are most extensive in the Northern Hemisphere, notably in the arid and semi-arid parts of northern Africa, the Near East, the former Soviet Union and Central Asia; they are also widespread in Australia and the Americas.
Management and use of Solonchaks Excessive accumulation of salts in soil affects plant growth in two ways: ÿ The salts aggravate drought stress because dissolved electrolytes create an osmotic potential that affects water uptake by plants. Before any water can be taken up from the soil, plants must compensate the combined forces of the matrix potential of the soil, i.e. the force with which the soil matrix retains water, and the osmotic potential. As a rule of thumb, the osmotic potential of a soil solution (in hectoPascals) amounts to some 650 × EC (dS/m). The total potential that can be compensated by plants (known as the critical leaf water head) varies strongly between plant species. Plant species that stem from the humid tropics have a comparatively low critical leaf water head. For example, green peppers can compensate a total soil moisture potential (matric plus osmotic forces) of only some 3 500 hPa whereas cotton, a crop that evolved in arid and semi-arid climates, survives some 25 000 hPa. ÿ The salts upset the balance of ions in the soil solution because nutrients are proportionately less available. Antagonistic effects are known to exist, e.g. between Na and K, between Na and Ca, and between Mg and K. In higher concentrations, the salts may be directly toxic to plants. Very harmful in this respect are Na ions and chloride ions (they disturb N metabolism). Farmers on Solonchaks adapt their cultivation methods. For example, plants on furrow-irrigated fields are not planted on the top of the ridges but at half height. This ensures that the roots benefit from the irrigation water while salt accumulation is strongest near the top of the ridge, away from the root systems. Strongly salt-affected soils have little agricultural value. They are used for extensive grazing of sheep, goats, camels and cattle, or lie idle. Only after the salts have been flushed from the soil (which then ceases to be a Solonchak) may good yields be hoped for. Application of irrigation water must not only satisfy the needs of the crop, but excess water must be applied above the irrigation requirement in order to maintain a downward water flow in the 295 94 World reference base for soil resources 2006
soil and to flush excess salts from the rootzone. Irrigation of crops in arid and semi- arid regions must be accompanied by drainage whereby drainage facilities should be designed to keep the groundwater table below the critical depth. Use of gypsum assists in maintaining hydraulic conductivity while salts are being flushed out with irrigation water.
SOLONETZ
Solonetz are soils with a dense, strongly structured, clayey subsurface horizon that has a high proportion of adsorbed Na and/or Mg ions. Solonetz that contain free
soda (Na2CO3) are strongly alkaline (field pH > 8.5). Common international names are alkali soils and sodic soils. In national soil classification systems many Solonetz correlate with: Sodosols (Australia), the Solonetzic order (Canada), various Solonetz types (Russian Federation), and to the natric Great Groups of several Orders (United States of America).
Summary description of Solonetz Connotation: Soils with a high content of exchangeable Na and/or Mg ions; from Russian sol, salt. Parent material: Unconsolidated materials, mostly fine-textured sediments. Environment: Solonetz are normally associated with flat lands in a climate with hot, dry summers, or with (former) coastal deposits that contain a high proportion of Na ions. Major concentrations of Solonetz are in flat or gently sloping grasslands with loess, loam or clay in semi-arid, temperate and subtropical regions. Profile development: A black or brown surface soil over a natric horizon with strong round-topped columnar structure elements. Well-developed Solonetz can have an albic eluviation horizon (beginning) directly over the natric horizon. A calcic or gypsic horizon may be present below the natric horizon. Many Solonetz have a field pH of about 8.5, indicative of the presence of free sodium carbonate.
Regional distribution of Solonetz Solonetz occur predominantly in areas with a steppe climate (dry summers and an annual precipitation sum of not more than 400–500 mm), in particular in flat lands with impeded vertical and lateral drainage. Smaller occurrences are found on inherently saline parent materials (e.g. marine clays or saline alluvial deposits). Worldwide, Solonetz cover some 135 million ha. Major Solonetz areas are found in Ukraine, Russian Federation, Kazakhstan, Hungary, Bulgaria, Romania, China, United States of America, Canada, South Africa, Argentina and Australia.
Management and use of Solonetz The suitability of virgin Solonetz for agricultural uses is dictated almost entirely by the depth and properties of the surface soil. A deep (> 25 cm) humus-rich surface soil is needed for successful arable crop production. However, most Solonetz have only a much shallower surface horizon, or have lost the surface horizon altogether. Solonetz amelioration has two basic elements: ÿ improvement of the porosity of the surface or subsurface soil; ÿ lowering of the ESP. Most reclamation attempts start with incorporation of gypsum or, exceptionally, calcium chloride in the soil. Where lime or gypsum occur at shallow depth in the soil body, deep ploughing (mixing the carbonate or gypsum containing subsoil with the surface soil) may make expensive amendments superfluous. Traditional reclamation strategies start with the planting of an Na-resistant crop, e.g. Rhodes grass, to gradually improve the permeability of the soil. Once a functioning pore system is in place, Na 296 Chapter 4 – Description, distribution, use and management of reference soil groups 95
ions are carefully leached from the soil with good-quality (Ca-rich) water (relatively pure water should be avoided because it exacerbates the dispersion problem). An extreme reclamation method (developed in Armenia and applied successfully to Solonetz with a calcic or petrocalcic horizon in the Arax Valley) uses diluted sulphuric acid (a waste product of the metallurgical industry) to dissolve CaCO3 contained in the soil. This brings Ca ions in the soil solution, which displace exchangeable Na. The practice improves soil aggregation and soil permeability. The resulting sodium sulphate (in the soil solution) is subsequently flushed out of the soil. In India, pyrite was applied to Solonetz to produce sulphuric acid, thus lowering extreme alkalinity and overcoming Fe deficiency. Ameliorated Solonetz can produce a fair crop foodgrain or forage. The majority of the world’s Solonetz have never been reclaimed and are used for extensive grazing or lie idle.
STAGNOSOLS
Stagnosols are soils with a perched water table showing redoximorphic features caused by surface water. Stagnosols are periodically wet and mottled in the topsoil and subsoil, with or without concretions and/or bleaching. A common name in many national classification systems for most Stagnosols is pseudogley. In the US Soil Taxonomy, many of them belong to the Aqualfs, Aquults, Aquents, Aquepts and Aquolls.
Summary description of Stagnosols Connotation: From Latin stagnare, to flood. Parent material: A wide variety of unconsolidated materials including glacial till, and loamy aeolian, alluvial and colluvial deposits, but also physically weathered silt stone. Environment: Most common in flat or gently sloping land in cool temperate to subtropical regions with humid to perhumid climate conditions. Profile development: Similar to strongly mottled Luvisols, Cambisols or Umbrisols; the topsoil can also be completely bleached (albic horizon). Regional distribution of Stagnosols Stagnosols cover 150–200 million ha worldwide; for the greater part in humid to perhumid temperate regions of West and Central Europe, North America, southeast Australia, and Argentina, associated with Luvisols as well as silty to clayey Cambisols and Umbrisols. They also occur in humid to perhumid subtropical regions, associated with Acrisols and Planosols.
Management and use of Stagnosols The agricultural suitability of Stagnosols is limited because of their oxygen deficiency resulting from stagnating water above a dense subsoil. Therefore, they have to be drained. However, in contrast to Gleysols, drainage with channels or pipes is in many cases insufficient. It is necessary to have a higher porosity in the subsoil in order to improve the hydraulic conductivity. This may be achieved by deep loosening or deep ploughing. Drained Stagnosols can be fertile soils owing to their moderate degree of leaching.
TECHNOSOLS
Technosols comprise a new RSG and combine soils whose properties and pedogenesis are dominated by their technical origin. They contain a significant amount of artefacts (something in the soil recognizably made or extracted from the earth by humans), or are sealed by technic hard rock (material created by humans, having properties unlike natural rock). They include soils from wastes (landfills, sludge, cinders, mine spoils 297 96 World reference base for soil resources 2006
and ashes), pavements with their underlying unconsolidated materials, soils with geomembranes and constructed soils in human-made materials. Technosols are often referred to as urban or mine soils. They are recognized in the new Russian soil classification system as Technogenic Superficial Formations.
Summary description of Technosols Connotation: Soils dominated or strongly influenced by human-made material; from Greek technikos, skilfully made Parent material: All kinds of materials made or exposed by human activity that otherwise would not occur at the Earth’s surface; pedogenesis in these soils is affected strongly by materials and their organization. Environment: Mostly in urban and industrial areas, in small areas, although in a complex pattern associated with other groups. Profile development: Generally none, although in old dumps (e.g. Roman rubble) evidence of natural pedogenesis can be observed, such as clay translocation. Lignite and fly ash deposits may exhibit over time vitric or andic properties (Zikeli, Kastler and Jahn, 2004; Zevenbergen et al., 1999). Original profile development may still be present in contaminated natural soils.
Regional distribution of Technosols Technosols are found throughout the world where human activity has led to the construction of artificial soil, sealing of natural soil, or extraction of material normally not affected by surface processes. Thus, cities, roads, mines, refuse dumps, oil spills, coal fly ash deposits and the like are included in Technosols.
Management and use of Technosols Technosols are affected strongly by the nature of the material or the human activity that placed it. They are more likely to be contaminated than soils from other RSGs. Many Technosols have to be treated with care as they may contain toxic substances resulting from industrial processes. Many Technosols, in particular the ones in refuse dumps, are currently covered with a layer of natural soil material in order to permit revegetation. Such a layer forms part of the Technosol, provided that the requirement of 20 percent or more (by volume, by weighted average) artefacts in the upper 100 cm of the soil surface or to continuous rock or a cemented or indurated layer, whichever is shallower, of the Technosol definition is met.
UMBRISOLS
Umbrisols accommodate soils in which organic matter has accumulated within the mineral surface soil (in most cases with low base saturation) to the extent that it significantly affects the behaviour and utilization of the soil. Umbrisols are the logical counterpart of soils with a mollic horizon and a high base saturation throughout (Chernozems, Kastanozems and Phaeozems). Not previously recognized at such a high taxonomic level, many of these soils are classified in other systems as: several Great Groups of Entisols and Inceptisols (United States of America); Humic Cambisols and Umbric Regosols (FAO); Sombric Brunisols and Humic Regosols (France); Much dark-humus soils (Russian Federation); Brown Podzolic soils (e.g. Indonesia); and Umbrisols (Romania).
Summary description of Umbrisols Connotation: Soils with dark topsoil; from Latin umbra, shade. Parent material: Weathering material of siliceous rock. 298 Chapter 4 – Description, distribution, use and management of reference soil groups 97
Environment: Humid climates; common in mountainous regions with little or no moisture deficit, in mostly cool areas but including tropical and subtropical mountains. Profile development: Dark brown umbric (seldom: mollic) surface horizon, in many cases over a cambic subsurface horizon with low base saturation.
Regional distribution of Umbrisols Umbrisols occur in cool, humid regions, mostly mountainous and with little or no soil moisture deficit. They occupy about 100 million ha throughout the world. In South America, Umbrisols are common in the Andean ranges of Colombia, Ecuador and, to a lesser extent, in Venezuela, Bolivia and Peru. They also occur in Brazil, e.g. in the Serra do Mar, and in Lesotho and South Africa, e.g. in the Drakensberg range. Umbrisols in North America are confined largely to the northwest Pacific seaboard. In Europe, Umbrisols occur along the northwest Atlantic seaboard, e.g. in Iceland, on the British Isles and in northwest Portugal and Spain. In Asia, they are found in the mountain ranges east and west of Lake Baikal, and on fringes of the Himalayas, notably in India, Nepal, China and Myanmar. Umbrisols occur at lower altitudes in Manipur (eastern India), in the Chin Hills (western Myanmar) and in Sumatra (Barisan range). In Oceania, Umbrisols are found in the mountain ranges of Papua New Guinea and southeast Australia and in the eastern parts of South Island, New Zealand.
Management and use of Umbrisols Many Umbrisols are under a natural or near-natural vegetation cover. Umbrisols above the tree line in the Andean, Himalayan and Central Asian mountain ranges, or at lower altitudes in northern and western Europe where the former forest vegetation has been largely cleared, carry a vegetation of short grasses of low nutritional value. Coniferous forest predominates in Brazil (e.g. Araucaria spp.) and in the United States of America (mainly Thuja, Tsuga and Pseudotsuga spp.). Umbrisols in tropical mountain areas in South Asia and Oceania are under montane evergreen forest. In the mountains of southern Mexico, the vegetation varies from tropical semi-deciduous forest to much cooler montane cloud forest. The predominance of sloping land and wet and cool climate conditions restricts utilization of many Umbrisols to extensive grazing. Management focuses on the introduction of improved grasses and correction of the soil pH by liming. Many Umbrisols are susceptible to erosion. The planting of perennial crops and bench or contour terracing offer possibilities for permanent agriculture on gentler slopes. Where conditions are suitable, cash crops may be grown, e.g. cereals and root crops in the United States of America, Europe and South America, or tea and cinchona in South Asia (Indonesia). Highland coffee on Umbrisols demands high management inputs to meet its stringent nutrient requirements. In New Zealand, Umbrisols have been transformed into highly productive soils, used for intensive sheep and dairy farming, and production of cash crops.
VERTISOLS
Vertisols are churning, heavy clay soils with a high proportion of swelling clays. These soils form deep wide cracks from the surface downward when they dry out, which happens in most years. The name Vertisols (from Latin vertere, to turn) refers to the constant internal turnover of soil material. Common local names for many Vertisols are: black cotton soils, regur (India), black turf soils (South Africa), margalites (Indonesia), Vertosols (Australia), Vertissolos (Brazil), and Vertisols (United States of America).
299 98 World reference base for soil resources 2006
Summary description of Vertisols Connotation: Churning, heavy clay soils; from Latin vertere, to turn. Parent material: Sediments that contain a high proportion of swelling clays, or products of rock weathering that have the characteristics of swelling clays. Environment: Depressions and level to undulating areas, mainly in tropical, subtropical, semi-arid to subhumid and humid climates with an alternation of distinct wet and dry seasons. The climax vegetation is savannah, natural grassland and/or woodland. Profile development: Alternate swelling and shrinking of expanding clays results in deep cracks in the dry season, and formation of slickensides and wedge-shaped structural elements in the subsurface soil. Gilgai microrelief is peculiar to Vertisols although not commonly encountered.
Regional distribution of Vertisols Vertisols cover 335 million ha worldwide. An estimated 150 million ha is potential cropland. Vertisols in the tropics cover some 200 million ha; one-quarter of this is considered to be useful land. Most Vertisols occur in the semi-arid tropics, with an average annual rainfall of 500–1 000 mm, but Vertisols are also found in the wet tropics, e.g. Trinidad (where the annual rainfall sum amounts to 3 000 mm). The largest Vertisol areas are on sediments that have a high content of smectitic clays or that produce such clays upon post-depositional weathering (e.g. in the Sudan), and on extensive basalt plateaus (e.g. in India and Ethiopia). Vertisols are also prominent in South Africa, Australia, the southwest of the United States of America (Texas), Uruguay, Paraguay and Argentina. Vertisols are typically found in lower landscape positions such as dry lake bottoms, river basins, lower river terraces, and other lowlands that are periodically wet in their natural state.
Management and use of Vertisols Large areas of Vertisols in the semi-arid tropics are still unused or are used only for extensive grazing, wood chopping, charcoal burning and the like. These soils have considerable agricultural potential, but adapted management is a precondition for sustained production. The comparatively good chemical fertility and their occurrence on extensive level plains where reclamation and mechanical cultivation can be envisaged are assets of Vertisols. Their physical soil characteristics and, notably, their difficult water management cause problems. Buildings and other structures on Vertisols are at risk, and engineers have to take special precautions to avoid damage. The agricultural uses of Vertisols range from very extensive (grazing, collection of fuelwood, and charcoal burning) through smallholder post-rainy season crop production (millet, sorghum, cotton and chickpeas) to small-scale (rice) and large-scale irrigated agriculture (cotton, wheat, barley, sorghum, chickpeas, flax, noug [Guzotia abessynica] and sugar cane). Cotton is known to perform well on Vertisols, allegedly because cotton has a vertical root system that is not damaged severely by cracking of the soil. Tree crops are generally less successful because tree roots find it difficult to establish themselves in the subsoil and are damaged as the soil shrinks and swells. Management practices for crop production should be directed primarily at water control in combination with conservation or improvement of soil fertility. The physical properties and the soil moisture regime of Vertisols represent serious management constraints. The heavy soil texture and domination of expanding clay minerals result in a narrow soil moisture range between moisture stress and water excess. Tillage is hindered by stickiness when the soil is wet and hardness when it is dry. The susceptibility of Vertisols to waterlogging may be the single most important factor that reduces the actual growing period. Excess water in the rainy season must be stored for post-rainy season use (water harvesting) on Vertisols with very slow infiltration rates. 300 Chapter 4 – Description, distribution, use and management of reference soil groups 99
One compensation for the shrink–swell characteristics is the phenomenon of self- mulching that is common on many Vertisols. Large clods produced by primary tillage break down with gradual drying into fine peds, which provide a passable seed bed with minimal effort. For the same reason, gully erosion on overgrazed Vertisols is seldom severe because gully walls soon assume a shallow angle of repose, which allows grass to become re-established more readily.
301 302 101
Chapter 5 Definitions of formative elements for second-level units of the WRB
The definitions of the formative elements for the second-level units relate to RSGs, diagnostic horizons, properties and materials, attributes such as colour, chemical conditions, texture, etc. Reference to the RSGs defined in Chapters 3 and 4 and the diagnostic features listed in Chapter 2 is given in italics. Usually, only a limited number of combinations will be possible; most of the definitions are mutually exclusive.
Abruptic (ap) Having an abrupt textural change within 100 cm of the soil surface.
Aceric (ae) Having a pH (1:1 in water) between 3.5 and 5 and jarosite mottles in some layer within 100 cm of the soil surface (in Solonchaks only).
Acric (ac) -1 Having an argic horizon that has a CEC (by 1 M NH4OAc) of less than 24 cmolc kg clay in some part to a maximum depth of 50 cm below its upper limit, either starting within 100 cm of the soil surface or within 200 cm of the soil surface if the argic horizon is overlain by loamy sand or coarser textures throughout, and a base saturation (by 1 M
NH4OAc) of less than 50 percent in the major part between 50 and 100 cm from the soil surface.
Acroxic (ao) -1 Having less than 2 cmolc kg fine earth exchangeable bases plus 1 M KCl exchangeable Al3+ in one or more layers with a combined thickness of 30 cm or more within 100 cm of the soil surface (in Andosols only).
Albic (ab) Having an albic horizon starting within 100 cm of the soil surface.
Hyperalbic (ha) Having an albic horizon starting within 50 cm of the soil surface and its lower boundary at a depth of 100 cm or more from the soil surface.
Glossalbic (gb) Showing tonguing of an albic into an argic or natric horizon.
Alcalic (ax) Having a pH (1:1 in water) of 8.5 or more throughout within 50 cm of the soil surface or to continuous rock or a cemented or indurated layer, whichever is shallower.
Alic (al) -1 Having an argic horizon that has a CEC (by 1 M NH4OAc) of 24 cmolc kg clay or more throughout or to a depth of 50 cm below its upper limit, whichever is shallower, 303 102 World reference base for soil resources 2006
either starting within 100 cm of the soil surface or within 200 cm of the soil surface if the argic horizon is overlain by loamy sand or coarser textures throughout, and a base
saturation (by 1 M NH4OAc) of less than 50 percent in the major part between 50 and 100 cm from the soil surface.
Aluandic (aa) Having one or more layers, cumulatively 30 cm or more thick, with andic properties and an acid oxalate (pH 3) extractable silica content of less than 0.6 percent, and an 1 2 Alpy /Alox of 0.5 or more, within 100 cm of the soil surface (in Andosols only).
Thaptaluandic (aab) Having one or more buried layers, cumulatively 30 cm or more thick, with andic properties and an acid oxalate (pH 3) extractable silica content of less than 3 4 0.6 percent, or an Alpy /Alox of 0.5 or more, within 100 cm of the soil surface.
Alumic (au) Having an Al saturation (effective) of 50 percent or more in some layer between 50 and 100 cm from the surface.
Andic (an) Having one or more layers, cumulatively 30 cm or more thick, with andic properties, within 100 cm of the soil surface.
Thaptandic (ba) Having one or more buried layers, cumulatively 30 cm or more thick, with andic properties, within 100 cm of the soil surface.
Anthraquic (aq) Having an anthraquic horizon.
Anthric (am) Having an anthric horizon.
Arenic (ar) Having a texture of loamy fine sand or coarser in a layer, 30 cm or more thick, within 100 cm of the soil surface.
Epiarenic (arp) Having a texture of loamy fine sand or coarser in a layer, 30 cm or more thick, within 50 cm of the soil surface.
Endoarenic (arn) Having a texture of loamy fine sand or coarser in a layer, 30 cm or more thick, between 50 and 100 cm from the soil surface.
1 Alpy: pyrophosphate-extractable aluminium, expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105 °C) basis. 2 Alox: acid oxalate-extractable aluminium (Blakemore, Searle and Daly, 1981), expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105 °C) basis. 3 Alpy: pyrophosphate-extractable aluminium, expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105o C) basis. 4 Alox: acid oxalate-extractable aluminium (Blakemore, Searle and Daly, 1981), expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105 °C) basis. 304 Chapter 5 – Definitions of formative elements for second-level units of the WRB 103
Aric (ai) Having only remnants of diagnostic horizons – disturbed by deep ploughing.
Aridic (ad) Having aridic properties without a takyric or yermic horizon.
Arzic (az) Having sulphate-rich groundwater in some layer within 50 cm of the soil surface during some time in most years and containing 15 percent or more gypsum averaged over a depth of 100 cm from the soil surface or to continuous rock or a cemented or indurated layer, whichever is shallower (in Gypsisols only).
Brunic (br) Having a layer, 15 cm or more thick, which meets criteria 2–4 of the cambic horizon but fails criterion 1, starting within 50 cm of the soil surface.
Calcaric (ca) Having calcaric material between 20 and 50 cm from the soil surface or between 20 cm and continuous rock or a cemented or indurated layer, whichever is shallower.
Calcic (cc) Having a calcic horizon or concentrations of secondary carbonates starting within 100 cm of the soil surface.
Cambic (cm) Having a cambic horizon starting within 50 cm of the soil surface.
Carbic (cb) Having a spodic horizon that does not turn redder on ignition (in Podzols only).
Carbonatic (cn) Having a salic horizon with a soil solution (1:1 in water) with a pH of 8.5 or more and - 2- - [HCO3 ] > [SO4 ] >> [Cl ] (in Solonchaks only).
Chloridic (cl) - 2- - Having a salic horizon with a soil solution (1:1 in water) with [Cl ] >> [SO4 ] > [HCO3 ] (in Solonchaks only).
Chromic (cr) Having within 150 cm of the soil surface a subsurface layer, 30 cm or more thick, that has a Munsell hue redder than 7.5 YR or that has both, a hue of 7.5 YR and a chroma, moist, of more than 4.
Clayic (ce) Having a texture of clay in a layer, 30 cm or more thick, within 100 cm of the soil surface.
Epiclayic (cep) Having a texture of clay in a layer, 30 cm or more thick, within 50 cm of the soil surface.
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Endoclayic (cen) Having a texture of clay in a layer, 30 cm or more thick, within 50 and 100 cm of the soil surface.
Colluvic (co) Having colluvic material, 20 cm or more thick, created by human-induced lateral movement.
Cryic (cy) Having a cryic horizon starting within 100 cm of the soil surface or a cryic horizon starting within 200 cm of the soil surface with evidence of cryoturbation in some layer within 100 cm of the soil surface.
Cutanic (ct) Having clay coatings in some parts of an argic horizon either starting within 100 cm of the soil surface or within 200 cm of the soil surface if the argic horizon is overlain by loamy sand or coarser textures throughout.
Densic (dn) Having natural or artificial compaction within 50 cm of the soil surface to the extent that roots cannot penetrate.
Drainic (dr) Having a histic horizon that is drained artificially starting within 40 cm of the soil surface.
Duric (du) Having a duric horizon starting within 100 cm of the soil surface.
Endoduric (nd) Having a duric horizon starting between 50 and 100 cm from the soil surface.
Hyperduric (duh) Having a duric horizon with 50 percent or more (by volume) durinodes starting within 100 cm of the soil surface.
Dystric (dy)
Having a base saturation (by 1 M NH4OAc) of less than 50 percent in the major part between 20 and 100 cm from the soil surface or between 20 cm and continuous rock or a cemented or indurated layer, or, in Leptosols, in a layer, 5 cm or more thick, directly above continuous rock.
Endodystric (ny)
Having a base saturation (by 1 M NH4OAc) of less than 50 percent throughout between 50 and 100 cm from the soil surface.
Epidystric (ed)
Having a base saturation (by 1 M NH4OAc) of less than 50 percent throughout between 20 and 50 cm from the soil surface.
306 Chapter 5 – Definitions of formative elements for second-level units of the WRB 105
Hyperdystric (hd)
Having a base saturation (by 1 M NH4OAc) of less than 50 percent throughout between 20 and 100 cm from the soil surface, and less than 20 percent in some layer within 100 cm of the soil surface.
Orthodystric (dyo)
Having a base saturation (by 1 M NH4OAc) of less than 50 percent throughout between 20 and 100 cm from the soil surface.
Ekranic (ek) Having technic hard rock starting within 5 cm of the soil surface and covering 95 percent or more of the horizontal extent of a pedon (in Technosols only).
Endoduric (nd) See Duric.
Endodystric (ny) See Dystric.
Endoeutric (ne) See Eutric.
Endofluvic (nf) See Fluvic.
Endogleyic (ng) See Gleyic.
Endoleptic (nl) See Leptic.
Endosalic (ns) See Salic.
Entic (et) Not an albic horizon and a loose spodic horizon (in Podzols only).
Epidystric (ed) See Dystric.
Epieutric (ee) See Eutric.
Epileptic (el) See Leptic.
Episalic (ea) See Salic.
Escalic (ec) Occurring in human-made terraces.
307 106 World reference base for soil resources 2006
Eutric (eu)
Having a base saturation (by 1 M NH4OAc) of 50 percent or more in the major part between 20 and 100 cm from the soil surface or between 20 cm and continuous rock or a cemented or indurated layer, or, in Leptosols, in a layer, 5 cm or more thick, directly above continuous rock.
Endoeutric (ne)
Having a base saturation (by 1 M NH4OAc) of 50 percent or more throughout between 50 and 100 cm from the soil surface.
Epieutric (ee)
Having a base saturation (by 1 M NH4OAc) of 50 percent or more throughout between 20 and 50 cm from the soil surface.
Hypereutric (he)
Having a base saturation (by 1 M NH4OAc) of 50 percent or more throughout between 20 and 100 cm from the soil surface and 80 percent or more in some layer within 100 cm of the soil surface.
Orthoeutric (euo)
Having a base saturation (by 1 M NH4OAc) of 50 percent or more throughout between 20 and 100 cm from the soil surface.
Eutrosilic (es) Having one or more layers, cumulatively 30 cm or more thick, with andic properties -1 and a sum of exchangeable bases of 15 cmolc kg fine earth or more within 100 cm of the surface (in Andosols only).
Ferralic (fl) Having a ferralic horizon starting within 200 cm of the soil surface (in Anthrosols only), or ferralic properties in at least some layer starting within 100 cm of the soil surface (in other soils).
Hyperferralic (flh) 1 -1 Having a Ferralic properties and a CEC (by 1 M NH4OAc) of less than 16 cmolc kg clay in at least some layer starting within 100 cm of the soil surface.
Hypoferralic (flw) Having in a layer, 30 cm or more thick, within 100 cm of the soil surface a CEC (by -1 1 M NH4OAc) of less than 4 cmolc kg fine earth and a Munsell chroma, moist, of 5 or more or a hue redder than 10 YR (in Arenosols only).
Ferric (fr) Having a ferric horizon starting within 100 cm of the soil surface.
Hyperferric (frh) Having a ferric horizon with 40 percent or more of the volume discrete reddish to blackish nodules starting within 100 cm of the soil surface.
1 See Annex 1. 308 Chapter 5 – Definitions of formative elements for second-level units of the WRB 107
Fibric (fi) Having, after rubbing, two-thirds or more (by volume) of the organic material consisting of recognizable plant tissue within 100 cm of the soil surface (in Histosols only).
Floatic (ft) Having organic material floating on water (in Histosols only).
Fluvic (fv) Having fluvic material in a layer, 25 cm or more thick, within 100 cm of the soil surface.
Endofluvic (nf) Having fluvic material in a layer, 25 cm or more thick, between 50 and 100 cm from the soil surface.
Folic (fo) Having a folic horizon starting within 40 cm of the soil surface.
Thaptofolic (fob) Having a buried folic horizon starting between 40 and 100 cm from the soil surface.
Fractipetric (fp) Having a strongly cemented or indurated horizon consisting of fractured or broken clods with an average horizontal length of less than 10 cm, starting within 100 cm of the soil surface.
Fractiplinthic (fa) Having a petroplinthic horizon consisting of fractured or broken clods with an average horizontal length of less than 10 cm, starting within 100 cm of the soil surface.
Fragic (fg) Having a fragic horizon starting within 100 cm of the soil surface.
Fulvic (fu) Having a fulvic horizon starting within 30 cm of the soil surface.
Garbic (ga) Having a layer, 20 cm or more thick within 100 cm of the soil surface, with 20 percent or more (by volume, by weighted average) artefacts containing 35 percent or more (by volume) organic waste materials (in Technosols only).
Gelic (ge) Having a layer with a soil temperature of 0 °C or less for two or more consecutive years starting within 200 cm of the soil surface.
Gelistagnic (gt) Having temporary water saturation at the soil surface caused by a frozen subsoil.
Geric (gr) Having geric properties in some layer within 100 cm of the soil surface.
309 108 World reference base for soil resources 2006
Gibbsic (gi) Having a layer, 30 cm or more thick, containing 25 percent or more gibbsite in the fine earth fraction within 100 cm of the soil surface.
Glacic (gc) Having a layer, 30 cm or more thick, containing 75 percent (by volume) or more ice within 100 cm of the soil surface.
Gleyic (gl) Having within 100 cm of the mineral soil surface in some parts reducing conditions and in 25 percent or more of the soil volume a gleyic colour pattern.
Endogleyic (ng) Having between 50 and 100 cm from the mineral soil surface in some parts reducing conditions and in 25 percent or more of the soil volume a gleyic colour pattern.
Epigleyic (glp) Having within 50 cm of the mineral soil surface in some parts reducing conditions and in 25 percent or more of the soil volume a gleyic colour pattern.
Glossalbic (gb) See Albic.
Glossic (gs) Showing tonguing of a mollic or umbric horizon into an underlying layer.
Molliglossic (mi) Showing tonguing of a mollic horizon into an underlying layer.
Umbriglossic (ug) Showing tonguing of an umbric horizon into an underlying layer.
Greyic (gz) Having Munsell colours with a chroma of 3 or less when moist, a value of 3 or less when moist and 5 or less when dry and uncoated silt and sand grains on structural faces within 5 cm of the mineral soil surface.
Grumic (gm) Having a soil surface layer with a thickness of 3 cm or more with a strong structure finer than very coarse granular (in Vertisols only).
Gypsic (gy) Having a gypsic horizon starting within 100 cm of the soil surface.
Gypsiric (gp) Having a gypsiric material between 20 and 50 cm from the soil surface.
Haplic (ha) Having a typical expression of certain features (typical in the sense that there is no further or meaningful characterization) and only used if none of the preceding qualifiers applies.
310 Chapter 5 – Definitions of formative elements for second-level units of the WRB 109
Hemic (hm) Having, after rubbing, between two-thirds and one-sixth (by volume) of the organic material consisting of recognizable plant tissue within 100 cm from the soil surface (in Histosols only).
Histic (hi) Having a histic horizon starting within 40 cm of the soil surface.
Thaptohistic (hib) Having a buried histic horizon starting between 40 and 100 cm from the soil surface.
Hortic (ht) Having a hortic horizon.
Humic (hu) Having the following organic carbon contents in the fine earth fraction as a weighted average in Ferralsols and Nitisols, 1.4 percent or more to a depth of 100 cm from the mineral soil surface; in Leptosols, 2 percent or more to a depth of 25 cm from the mineral soil surface; in other soils, 1 percent or more to a depth of 50 cm from the mineral soil surface.
Hyperhumic (huh) Having an organic carbon content of 5 percent or more as a weighted average in the fine earth fraction to a depth of 50 cm from the mineral soil surface.
Hydragric (hg) Having an anthraquic horizon and an underlying hydragric horizon, the latter starting within 100 cm of the soil surface.
Hydric (hy) Having within 100 cm of the soil surface one or more layers with a combined thickness of 35 cm or more, which have a water retention at 1 500 kPa (in undried samples) of 100 percent or more (in Andosols only).
Hydrophobic (hf) Water-repellent, i.e. water stands on a dry soil for the duration of 60 seconds or more (in Arenosols only).
Hyperalbic (ha) See Albic.
Hyperalic (hl) Having an argic horizon that has a silt to clay ratio of less than 0.6 and an Al saturation (effective) of 50 percent or more, throughout or to a depth of 50 cm below its upper limit, whichever is shallower (in Alisols only).
Hypercalcic (hc) Having a calcic horizon with 50 percent or more (by mass) calcium carbonate equivalent (in Calcisols only).
Hyperdystric (hd) See Dystric. 311 110 World reference base for soil resources 2006
Hypereutric (he) See Eutric.
Hypergypsic (hp) Having a gypsic horizon with 50 percent or more (by mass) gypsum (in Gypsisols only).
Hyperochric (ho) Having a mineral topsoil layer, 5 cm or more thick, with a Munsell value, dry, of 5.5 or more that turns darker on moistening, an organic carbon content of less than 0.4 percent, a platy structure in 50 percent or more of the volume, and a surface crust.
Hypersalic (hs) See Salic.
Hyperskeletic (hk) Containing less than 20 percent (by volume) fine earth averaged over a depth of 75 cm from the soil surface or to continuous rock, whichever is shallower.
Hypocalcic (wc) Having a calcic horizon with a calcium carbonate equivalent content in the fine earth fraction of less than 25 percent and starting within 100 cm of the soil surface (in Calcisols only).
Hypogypsic (wg) Having a gypsic horizon with a gypsum content in the fine earth fraction of less than 25 percent and starting within 100 cm of the soil surface (in Gypsisols only).
Hypoluvic (wl) Having an absolute clay increase of 3 percent or more within 100 cm of the soil surface (in Arenosols only).
Hyposalic (ws) See Salic.
Hyposodic (wn) See Sodic.
Irragric (ir) Having an irragric horizon.
Lamellic (ll) Having clay lamellae with a combined thickness of 15 cm or more within 200 cm of the soil surface.
Laxic (la) Having a bulk density of less than 0.8 kg dm-3, in a mineral soil layer, 20 cm or more thick, starting within 75 cm of the soil surface.
Leptic (le) Having continuous rock starting within 100 cm of the soil surface.
312 Chapter 5 – Definitions of formative elements for second-level units of the WRB 111
Endoleptic (nl) Having continuous rock starting between 50 and 100 cm from the soil surface.
Epileptic (el) Having continuous rock starting within 50 cm of the soil surface.
Lignic (lg) Having inclusions of intact wood fragments, which make up one-quarter or more of the soil volume, within 50 cm of the soil surface (in Histosols only).
Limnic (lm) Having limnic material, cumulatively 10 cm or more thick, within 50 cm of the soil surface.
Linic (lc) Having a continuous, very slowly permeable to impermeable constructed geomembrane of any thickness starting within 100 cm of the soil surface.
Lithic (li) Having continuous rock starting within 10 cm of the soil surface (in Leptosols only).
Nudilithic (nt) Having continuous rock at the soil surface (in Leptosols only).
Lixic (lx) -1 Having an argic horizon that has a CEC (by 1 M NH4OAc) of 24 cmolc kg clay or more in some part to a maximum depth of 50 cm below its upper limit, either starting within 100 cm of the soil surface or within 200 cm of the soil surface if the argic horizon is overlain by loamy sand or coarser textures throughout, and a base saturation (by 1 M
NH4OAc) of 50 percent or more in the major part between 50 and 100 cm from the soil surface.
Luvic (lv) -1 Having an argic horizon that has a CEC of 24 cmolc kg clay or more throughout or to a depth of 50 cm below its upper limit, whichever is shallower, either starting within 100 cm of the soil surface or within 200 cm of the soil surface if the argic horizon is overlain by loamy sand or coarser textures throughout, and a base saturation (by 1 M
NH4OAc) of 50 percent or more in the major part between 50 and 100 cm from the soil surface.
Magnesic (mg) Having an exchangeable Ca to Mg ratio of less than 1 in the major part within 100 cm of the soil surface or to continuous rock or a cemented or indurated layer, whichever is shallower.
Manganiferric (mf) Having a ferric horizon starting within 100 cm of the soil surface in which half or more of the nodules or mottles are black.
Mazic (mz) Massive and hard to very hard in the upper 20 cm of the soil (in Vertisols only).
313 112 World reference base for soil resources 2006
Melanic (ml) Having a melanic horizon starting within 30 cm of the soil surface (in Andosols only).
Mesotrophic (ms)
Having a base saturation (by 1 M NH4OAc) of less than 75 percent at a depth of 20 cm from the soil surface (in Vertisols only).
Mollic (mo) Having a mollic horizon.
Molliglossic (mi) See Glossic.
Natric (na) Having a natric horizon starting within 100 cm of the soil surface.
Nitic (ni) Having a nitic horizon starting within 100 cm of the soil surface.
Novic (nv) Having above the soil that is classified at the RSG level, a layer with recent sediments (new material), 5 cm or more and less than 50 cm thick.
Areninovic (anv) Having above the soil that is classified at the RSG level, a layer with recent sediments (new material), 5 cm or more and less than 50 cm thick, which has a texture of loamy fine sand or coarser in its major part.
Clayinovic (cnv) Having above the soil that is classified at the RSG level, a layer with recent sediments (new material), 5 cm or more and less than 50 cm thick, which has a texture of clay in its major part.
Siltinovic (snv) Having above the soil that is classified at the RSG level, a layer with recent sediments (new material), 5 cm or more and less than 50 cm thick, which has a texture of silt, silt loam, silty clay loam or silty clay in its major part.
Nudilithic (nt) See Lithic.
Ombric (om) Having a histic horizon saturated predominantly with rainwater starting within 40 cm of the soil surface (in Histosols only).
Ornithic (oc) Having a layer 15 cm or more thick with ornithogenic material starting within 50 cm of the soil surface.
Ortsteinic (os) Having a cemented spodic horizon (ortstein) (in Podzols only).
314 Chapter 5 – Definitions of formative elements for second-level units of the WRB 113
Oxyaquic (oa) Saturated with oxygen-rich water during a period of 20 or more consecutive days and not a gleyic or stagnic colour pattern in some layer within 100 cm of the soil surface.
Pachic (ph) Having a mollic or umbric horizon 50 cm or more thick.
Pellic (pe) Having in the upper 30 cm of the soil a Munsell value, moist, of 3.5 or less and a chroma, moist, of 1.5 or less (in Vertisols only).
Petric (pt) Having a strongly cemented or indurated layer starting within 100 cm of the soil surface.
Endopetric (ptn) Having a strongly cemented or indurated layer starting between 50 and 100 cm from the soil surface.
Epipetric (ptp) Having a strongly cemented or indurated layer starting within 50 cm of the soil surface.
Petrocalcic (pc) Having a petrocalcic horizon starting within 100 cm of the soil surface.
Petroduric (pd) Having a petroduric horizon starting within 100 cm of the soil surface.
Petrogleyic (py) Having a layer, 10 cm or more thick, with an oximorphic colour pattern1, 15 percent or more (by volume) of which is cemented (bog iron), within 100 cm of the surface.
Petrogypsic (pg) Having a petrogypsic horizon starting within 100 cm of the soil surface.
Petroplinthic (pp) Having a petroplinthic horizon starting within 100 cm of the soil surface.
Petrosalic (ps) Having within 100 cm of the soil surface, a layer, 10 cm or more thick, which is cemented by salts more soluble than gypsum.
Pisoplinthic (px) Having a pisoplinthic horizon starting within 100 cm of the soil surface.
Placic (pi) Having within 100 cm of the soil surface, an iron pan, between 1 and 25 mm thick, that is continuously cemented by a combination of organic matter, Fe and/or Al.
1 As defined in the gleyic colour pattern. 315 114 World reference base for soil resources 2006
Plaggic (pa) Having a plaggic horizon.
Plinthic (pl) Having a plinthic horizon starting within 100 cm of the soil surface.
Posic (po)
Having a zero or positive charge (pHKCl - pHwater, both 1:1) in a layer, 30 cm or more thick, starting within 100 cm of the soil surface (in Plinthosols and Ferralsols only).
Profondic (pf) Having an argic horizon in which the clay content does not decrease by 20 percent or more (relative) from its maximum within 150 cm of the soil surface.
Protic (pr) Showing no soil horizon development (in Arenosols only).
Puffic (pu) Having a crust pushed up by salt crystals (in Solonchaks only).
Reductaquic (ra) Saturated with water during the thawing period and at some time of the year reducing conditions above a cryic horizon and within 100 cm of the soil surface (in Cryosols only).
Reductic (rd) Having reducing conditions in 25 percent or more of the soil volume within 100 cm of the soil surface caused by gaseous emissions, e.g. methane or carbon dioxide (in Technosols only).
Regic (rg) Not having buried horizons (in Anthrosols only).
Rendzic (rz) Having a mollic horizon that contains or immediately overlies calcaric materials containing 40 percent or more calcium carbonate equivalent.
Rheic (rh) Having a histic horizon saturated predominantly with groundwater or flowing surface water starting within 40 cm of the soil surface (in Histosols only).
Rhodic (ro) Having within 150 cm of the soil surface a subsurface layer, 30 cm or more thick, with a Munsell hue redder than 5 YR (3.5 YR or redder), a value, moist, of less than 3.5 and a value, dry, no more than one unit higher than the moist value.
Rubic (ru) Within 100 cm of the soil surface a subsurface layer, 30 cm or more thick, with a Munsell hue redder than 10 YR or a chroma, moist, of 5 or more (in Arenosols only).
Ruptic (rp) Having a lithological discontinuity within 100 cm of the soil surface.
316 Chapter 5 – Definitions of formative elements for second-level units of the WRB 115
Rustic (rs) Having a spodic horizon that turns redder on ignition (in Podzols only).
Salic (sz) Having a salic horizon starting within 100 cm of the soil surface.
Endosalic (ns) Having a salic horizon starting between 50 and 100 cm from the soil surface.
Episalic (ea) Having a salic horizon starting within 50 cm of the soil surface.
Hypersalic (hs) -1 Having an ECe of 30 dS m or more at 25 °C in some layer within 100 cm of the soil surface.
Hyposalic (ws) -1 Having an ECe of 4 dS m or more at 25 °C in some layer within 100 cm of the soil surface.
Sapric (sa) Having, after rubbing, less than one-sixth (by volume) of the organic material consisting of recognizable plant tissue within 100 cm of the soil surface (in Histosols only).
Silandic (sn) Having one or more layers, cumulatively 30 cm or more thick, with andic properties and an acid oxalate (pH 3) extractable silica (Siox) content of 0.6 percent or more, or an
Alpy to Alox ratio of less than 0.5 within 100 cm of the soil surface (in Andosols only).
Thaptosilandic (snb) Having one or more buried layers, cumulatively 30 cm or more thick, with andic
properties and an acid oxalate (pH 3) extractable silica (Siox) content of 0.6 percent
or more, or an Alpy to Alox ratio of less than 0.5 within 100 cm of the soil surface.
Siltic (sl) Having a texture of silt, silt loam, silty clay loam or silty clay in a layer, 30 cm or more thick, within 100 cm of the soil surface.
Endosiltic (sln) Having a texture of silt, silt loam, silty clay loam or silty clay in a layer, 30 cm or more thick, within 50 and 100 cm of the soil surface.
Episiltic (slp) Having a texture of silt, silt loam, silty clay loam or silty clay in a layer, 30 cm or more thick, within 50 cm of the soil surface.
Skeletic (sk) 40 percent or more (by volume) gravel or other coarse fragments averaged over a depth of 100 cm from the soil surface or to continuous rock or a cemented or indurated layer, whichever is shallower.
317 116 World reference base for soil resources 2006
Endoskeletic (skn) Having 40 percent or more (by volume) gravel or other coarse fragments averaged over a depth between 50 and 100 cm from the soil surface.
Episkeletic (skp) Having 40 percent or more (by volume) gravel or other coarse fragments averaged over a depth of 50 cm from the soil surface.
Sodic (so) Having 15 percent or more exchangeable Na plus Mg on the exchange complex within 50 cm of the soil surface throughout.
Endosodic (son) Having 15 percent or more exchangeable Na plus Mg on the exchange complex between 50 and 100 cm from the soil surface throughout.
Hyposodic (sow) Having 6 percent or more exchangeable Na on the exchange complex in a layer, 20 cm or more thick, within 100 cm of the soil surface.
Solodic (sc) Having a layer, 15 cm or more thick within 100 cm of the soil surface, with the columnar or prismatic structure of the natric horizon, but lacking its sodium saturation requirements.
Sombric (sm) Having a sombric horizon starting within 150 cm of the soil surface.
Spodic (sd) Having a spodic horizon starting within 200 cm of the mineral soil surface.
Spolic (sp) Having a layer, 20 cm or more thick within 100 cm of the soil surface, with 20 percent or more (by volume, by weighted average) artefacts containing 35 percent or more (by volume) of industrial waste (mine spoil, dredgings, rubble, etc.) (in Technosols only).
Stagnic (st) Having within 100 cm of the mineral soil surface in some parts reducing conditions for some time during the year and in 25 percent or more of the soil volume, single or in combination, a stagnic colour pattern or an albic horizon.
Endostagnic (stn) Having between 50 and 100 cm from the mineral soil surface in some parts reducing conditions for some time during the year and in 25 percent or more of the soil volume, single or in combination, a stagnic colour pattern or an albic horizon.
Epistagnic (stn) Having within 50 cm of the mineral soil surface in some parts reducing conditions for some time during the year and in 25 percent or more of the soil volume, single or in combination, a stagnic colour pattern or an albic horizon.
Subaquatic (sq) Being permanently submerged under water not deeper than 200 cm. 318 Chapter 5 – Definitions of formative elements for second-level units of the WRB 117
Sulphatic (su) 2- - Having a salic horizon with a soil solution (1:1 in water) with [SO4 ] >> [HCO3 ] > [Cl-] (in Solonchaks only).
Takyric (ty) Having a takyric horizon.
Technic (te) Having 10 percent or more (by volume, by weighted average) artefacts in the upper 100 cm from the soil surface or to continuous rock or a cemented or indurated layer, whichever is shallower.
Tephric (tf) Having tephric material to a depth of 30 cm or more from the soil surface or to continuous rock, whichever is shallower.
Terric (tr) Having a terric horizon.
Thaptandic (ba) See Andic.
Thaptovitric (bv) See Vitric.
Thionic (ti) Having a thionic horizon or a layer with sulphidic material, 15 cm or more thick, starting within 100 cm of the soil surface.
Hyperthionic (tih) Having a thionic horizon starting within 100 cm of the soil surface and a pH (1:1 in water) less than 3.5.
Orthothionic (tio) Having a thionic horizon starting within 100 cm of the soil surface and a pH (1:1 in water) between 3.5 and 4.0.
Protothionic (tip) Having a layer with sulphidic material, 15 cm or more thick, starting within 100 cm of the soil surface.
Thixotropic (tp) Having in some layer within 50 cm of the soil surface material that changes, under pressure or by rubbing, from a plastic solid into a liquefied stage and back into the solid condition.
Tidalic (td) Being flooded by tidewater but not covered by water at mean low tide.
Toxic (tx) Having in some layer within 50 cm of the soil surface toxic concentrations of organic or inorganic substances other than ions of Al, Fe, Na, Ca and Mg.
319 118 World reference base for soil resources 2006
Anthrotoxic (atx) Having in some layer within 50 cm of the soil surface sufficiently high and persistent concentrations of organic or inorganic substances to markedly affect the health of humans who come in regular contact with the soil.
Ecotoxic (etx) Having in some layer within 50 cm of the soil surface sufficiently high and persistent concentrations of organic or inorganic substances to markedly affect soil ecology, in particular the populations of the mesofauna.
Phytotoxic (ptx) Having in some layer within 50 cm of the soil surface sufficiently high or low concentrations of ions other than Al, Fe, Na, Ca and Mg, to markedly affect plant growth.
Zootoxic (ztx) Having in some layer within 50 cm of the soil surface sufficiently high and persistent concentrations of organic or inorganic substances to markedly affect the health of animals, including humans, that ingest plants grown on these soils.
Transportic (tn) Having a layer, 30 cm or more thick, with solid or liquid material that has been moved from a source area outside the immediate vicinity of the soil by intentional human activity, usually with the aid of machinery, and without substantial reworking or displacement by natural forces
Turbic (tu) Having cryoturbation features (mixed material, disrupted soil horizons, involutions, organic intrusions, frost heave, separation of coarse from fine materials, cracks or patterned ground) at the soil surface or above a cryic horizon and within 100 cm of the soil surface.
Umbric (um) Having an umbric horizon.
Umbriglossic (ug) See Glossic.
Urbic (ub) Having a layer, 20 cm or more thick within 100 cm of the soil surface, with 20 percent or more (by volume, by weighted average) artefacts containing 35 percent or more (by volume) of rubble and refuse of human settlements (in Technosols only).
Vermic (vm) Having 50 percent or more (by volume, by weighted average) of worm holes, casts, or filled animal burrows in the upper 100 cm of the soil or to continuous rock or a cemented or indurated layer, whichever is shallower.
Vertic (vr) Having a vertic horizon or vertic properties starting within 100 cm of the soil surface.
320 Chapter 5 – Definitions of formative elements for second-level units of the WRB 119
Vetic (vt) Having an ECEC (sum of exchangeable bases plus exchangeable acidity in 1 M KCl) of -1 less than 6 cmolc kg clay in some subsurface layer within 100 cm of the soil surface.
Vitric (vi) Having one or more layers, cumulatively 30 cm or more thick, with vitric properties, within 100 cm of the soil surface.
Thaptovitric (bv) Having one or more buried layers, cumulatively 30 cm or more thick, with vitric properties, within 100 cm of the soil surface.
Voronic (vo) Having a voronic horizon (in Chernozems only).
Xanthic (xa) Having a ferralic horizon that has in a subhorizon, 30 cm or more thick within 150 cm of the soil surface, a Munsell hue of 7.5 YR or yellower and a value, moist, of 4 or more and a chroma, moist, of 5 or more.
Yermic (ye) Having a yermic horizon, including a desert pavement.
Nudiyermic (yes) Having a yermic horizon without a desert pavement.
SPECIFIERS
The following specifiers may be used to indicate depth of occurrence, or to express the intensity of soil characteristics. Their code is always added after the qualifier code. The specifiers are combined with other elements into one word, e.g. Endoskeletic. A triple combination, e.g. Epihyperdystric, is allowed.
Bathy (..d) Horizon, property or material starting between 100 and 200 cm from the soil surface.
Cumuli (..c) Having a repetitive accumulation of material of 50 cm or more at the soil surface (e.g. cumulinovic and cumulimollic).
Endo (..n) Horizon, property or material starting between 50 and 100 cm from the soil surface.
Epi (..p) Horizon, property or material starting within 50 cm of the soil surface.
Hyper (..h) Having a strong expression of certain features.
Hypo (..w) Having a weak expression of certain features.
321 120 World reference base for soil resources 2006
Ortho (..o) Having a typical expression of certain features (typical in the sense that no further or meaningful characterization is made).
Para (..r) Having a resemblance to certain features (e.g. Paralithic).
Proto (..t) Indicating a precondition or an early stage of development of certain features (e.g. Protothionic).
Thapto (..b) Having a buried horizon within 100 cm of the surface (given in combination with the buried diagnostic horizon, e.g. Thaptomollic).
322 121
References
Asiamah, R.D. 2000. Plinthite and conditions for its hardening in agricultural soils in Ghana. Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. (Thesis) Blakemore, L.C., Searle, P.L. & Daly, B.K. 1981. Soil Bureau analytical methods. A method for chemical analysis of soils. NZ Soil Bureau Sci. Report 10A. DSIRO. Bridges, E.M. 1997. World soils. 3rd edition. Cambridge, UK, Cambridge University Press. Buivydaité, V.V., Vaičys, M., Juodis, J. & Motuzas, A. 2001. Lietuvos dirvožemių klasifikacija. Vilnius, Lievos mokslas. Burt, R., ed. 2004. Soil survey laboratory methods manual. Soil Survey Investigations Report No. 42, Version 4.0. Lincoln, USA, Natural Resources Conservation Service. Cooperative Research Group on Chinese Soil Taxonomy (CRGCST). 2001. Chinese soil taxonomy. Beijing and New York, USA, Science Press. CPCS. 1967. Classification des sols. Grignon, France, Ecole nationale supérieure agronomique. 87 pp. European Soil Bureau Network/European Commission. 2005. Soil atlas of Europe. Luxembourg, Office for Official Publications of the European Communities. FAO. 1966. Classification of Brazilian soils, by J. Bennema. Report to the Government of Brazil. FAO EPTA Report No. 2197. Rome. FAO. 1988. Soil map of the world. Revised legend, by FAO–UNESCO–ISRIC. World Soil Resources Report No. 60. Rome. FAO. 1994. World Reference Base for Soil Resources, by ISSS–ISRIC–FAO. Draft. Rome/ Wageningen, Netherlands. FAO. 1998. World Reference Base for Soil Resources, by ISSS–ISRIC–FAO. World Soil Resources Report No. 84. Rome. FAO. 2001a. Lecture notes on the major soils of the world (with CD-ROM), by P. Driessen, J. Deckers, O. Spaargaren & F, Nachtergaele, eds. World Soil Resources Report No. 94. Rome. FAO. 2001b. Major soils of the world. Land and Water Digital Media Series No. 19. Rome. FAO. 2003. Properties and management of soils of the tropics. Land and Water Digital Media Series No. 24. Rome. FAO. 2005. Properties and management of drylands. Land and Water Digital Media Series No. 31. Rome. FAO. 2006. Guidelines for soil description. 4th edition. Rome. FAO–UNESCO. 1971–1981. Soil map of the world 1:5 000 000. 10 Volumes. Paris, UNESCO. Fieldes, M. & Perrott, K.W. 1966. The nature of allophane soils: 3. Rapid field and laboratory test for allophane. N. Z. J. Sci., 9: 623–629. Gong, Z., Zhang, X., Luo, G., Shen, H. & Spaargaren, O.C. 1997. Extractable phosphorus in soils with a fimic epipedon. Geoderma, 75: 289–296. Hewitt, A.E. 1992. New Zealand soil classification. DSIR Land Resources Scientific Report 19. Lower Hutt. Ito, T., Shoji, S., Shirato, Y. & Ono, E. 1991. Differentiation of a spodic horizon from a buried A horizon. Soil Sci. Soc. Am. J., 55: 438–442. Krogh, L. & Greve, M.H. 1999. Evaluation of World Reference Base for Soil Resources and FAO Soil Map of the World using nationwide grid soil data from Denmark. Soil Use & Man., 15(3):157–166. Nachtergaele, F. 2005. The “soils” to be classified in the World Reference Base for Soil Resources. Euras. Soil Sci., 38(Suppl. 1): 13–19.
323 122 World reference base for soil resources 2006
Němecěk, J. Macků, J., Vokoun, J., Vavříě, D. & Novák, P. 2001. Taxonomický klasifikační system půd České Republiky. Prague, ČZU. Olsen, S.R., Cole, C.V., Watanabe, F.S. & Dean, L.A. 1954. Estimation of available phosphorus by extraction with sodium bicarbonate. USDA Circ. 939. Washington, DC, United States Department of Agriculture. Poulenard, J. & Herbillon, A.J. 2000. Sur l’existence de trois catégories d’horizons de référence dans les Andosols. C. R. Acad. Sci. Paris, Sci. Terre & plan., 331: 651–657. Shishov, L.L., Tonkonogov, V.D., Lebedeva, I.I. & Gerasimova, M.I., eds. 2001. Russian soil classification system. Moscow, V.V. Dokuchaev Soil Science Institute. Shoji, S., Nanzyo, M., Dahlgren, R.A. & Quantin, P. 1996. Evaluation and proposed revisions of criteria for Andosols in the World Reference Base for Soil Resources. Soil Sci., 161(9): 604–615. Soil Survey Staff. 1999. Soil taxonomy. A basic system of soil classification for making and interpreting soil surveys. 2nd Edition. Agric. Handbook 436. Washington, DC, Natural Resources Conservation Service, United States Department of Agriculture. Soil Survey Staff. 2003. Keys to soil taxonomy. 9th Edition. Washington, DC, Natural Resources Conservation Service, United States Department of Agriculture. Sombroek, W.G. 1986. Identification and use of subtypes of the argillic horizon. In: Proceedings of the International Symposium on Red Soils, pp. 159–166, Nanjing, November 1983. Beijing, Institute of Soil Science, Academia Sinica, Science Press, and Amsterdam, Netherlands, Elsevier. Takahashi, T., Nanzyo, M. & Shoji, S. 2004. Proposed revisions to the diagnostic criteria for andic and vitric horizons and qualifiers of Andosols in the World Reference Base for Soil Resources. Soil Sci. Plant Nutr., 50 (3): 431–437. Van Reeuwijk, L.P. 2006. Procedures for soil analysis. 7th Edition. Technical Report 9. Wageningen, Netherlands, ISRIC – World Soil Information. Varghese, T. & Byju, G. 1993. Laterite soils. Their distribution, characteristics, classification and management. Technical Monograph 1. Thirivananthapuram, Sri Lanka, State Committee on Science, Technology and Environment. Zevenbergen, C., Bradley, J.P., van Reeuwijk, L.P., Shyam, A.K., Hjelmar, O. & Comans, R.N.J. 1999. Clay formation and metal fixation during weathering of coal fly ash. Env. Sci. & Tech., 33(19): 3405–3409. Zikeli, S., Kastler, M. & Jahn, R. 2005. Classification of Anthrosols with vitric/andic properties derived from lignite ash. Geoderma, 124: 253–265.
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Annex 1 Summary of analytical procedures for soil characterization
This annex provides summaries of recommended analytical procedures to be used for soil characterization for the World Reference Base for Soil Resources. Full descriptions can be found in Procedures for soil analysis (Van Reeuwijk, 2006) and the USDA Soil Survey Laboratory Methods Manual (Burt, 2004).
1. SAMPLE PREPARATION Samples are air-dried or, alternatively, oven-dried at a maximum of 40 °C. The fine earth fraction is obtained by sieving the dry sample with a 2-mm sieve. Clods not passing through the sieve are crushed (not ground) and sieved again. Gravel, rock fragments, etc. not passing through the sieve are treated separately. In special cases where air-drying causes unacceptable irreversible changes in certain soil properties (e.g. in peat and soils with andic properties), samples are kept and treated in the field-moist state.
2. MOISTURE CONTENT Calculation of results of soil analysis is done on the basis of oven-dry (105 °C) soil mass.
3. PARTICLE-SIZE ANALYSIS The mineral part of the soil is separated into various size fractions and the proportion of these fractions is determined. The determination comprises all material, i.e. including gravel and coarser material, but the procedure itself is applied to the fine earth (< 2 mm) only. The pre-treatment of the sample is aimed at complete dispersion of the primary particles. Therefore, cementing materials (usually of secondary origin) such as organic matter and calcium carbonate may have to be removed. In some cases, de-ferration also needs to be applied. However, depending on the aim of study, it may be fundamentally wrong to remove cementing materials. Thus, all pre-treatments are to be considered optional. However, for soil characterization purposes, removal of organic matter by
H2O2 and of carbonates by HCl is routinely carried out. After this pre-treatment, the sample is shaken with a dispersing agent and sand is separated from clay and silt with a 63-μm sieve. The sand is fractionated by dry sieving, the clay and silt fractions are determined by the pipette method or, alternatively, by the hydrometer method.
4. WATER-DISPERSIBLE CLAY This is the clay content found when the sample is dispersed with water without any pre-treatment to remove cementing compounds and without use of a dispersing agent. The proportion of natural clay to total clay can be used as a structure stability indicator.
5. SOIL WATER RETENTION The water content is determined of soil samples that have been equilibrated with water at various suction (tension) values. For low suction values, undisturbed core samples are equilibrated on a silt and kaolin bath; for high suction values, disturbed samples are 325 124 World reference base for soil resources 2006
equilibrated in pressure plate extractors. The bulk density is calculated from the core sample mass.
6. BULK DENSITY Soil bulk density is the mass per unit volume of soil. As bulk density changes with water content, the water status of the sample must be specified. Two different procedures can be used: ÿ Undisturbed core samples. A metal cylinder of known volume is pressed into the soil. The moist sample mass is recorded. This may be the field-moist state or the state after equilibrating the sample at a specified water tension. The sample is then oven-dried and weighed again. The bulk density is the ratio of dry mass to volume at the determined water content and/or the specified water tension. ÿ Coated clods. Field-occurring clods are coated with plastic lacquer (e.g. Saran dissolved in methyl ethyl ketone) to allow determination of underwater mass. This gives the volume of the clod. The moist sample mass is recorded. This may be the field-moist state or the state after equilibrating the clod at specified water suction. The sample is then oven-dried and weighed again. The bulk density is the ratio of dry mass to volume at the specified water suction. Note: The determination of bulk density is very sensitive to errors, particularly caused by non-representativeness of the samples (stones, cracks, roots, etc.). Therefore, determinations should always be made in triplicate.
7. COEFFICIENT OF LINEAR EXTENSIBILITY (COLE) The COLE gives an indication of the reversible shrink–swell capacity of a soil. It is calculated from the dry bulk density and the bulk density at 33 kPa water suction. The COLE value is expressed in centimetres per centimetre or as a percentage value.
8. PH The pH of the soil is potentiometrically measured in the supernatant suspension of a
1:2½ soil:liquid mixture. The liquid is either distilled water (pH-H2O) or a 1 M KCl solution (pH-KCl). In some cases definitions for classifcation specify a 1:1 soil:water ratio.
9. ORGANIC CARBON The Walkley–Black procedure is followed. This involves a wet combustion of the organic matter with a mixture of potassium dichromate and sulphuric acid at about 125 °C. The residual dichromate is titrated against ferrous sulphate. To compensate for incomplete destruction, an empirical correction factor of 1.3 is applied in the calculation of the result. Note: Other procedures, including carbon analysers (dry combustion) may also be used. In these cases a qualitative test for carbonates on effervescence with HCl is recommended and, if present, a correction for inorganic C (see Carbonate below) is required.
10. CARBONATE The rapid titration method by Piper (also called acid neutralization method) is used. The sample is treated with dilute HCl and the residual acid is titrated. The results are referred to as calcium carbonate equivalent as the dissolution is not selective for calcite and also other carbonates such as dolomite are dissolved to some extent. Note: Other procedures such as the Scheibler volumetric method may also be used.
326 Annex 1 – Summary of analytical procedures for soil characterization 125
11. GYPSUM Gypsum is dissolved by shaking the sample with water. It is then selectively precipitated from the extract by adding acetone. This precipitate is re-dissolved in water and the Ca concentration is determined as a measure for gypsum.
12. CATION EXCHANGE CAPACITY (CEC) AND EXCHANGEABLE BASES The ammonium acetate pH 7 method is used. The sample is percolated with ammonium acetate (pH 7) and the bases are measured in the percolate. The sample is subsequently percolated with sodium acetate (pH 7), the excess salt is then removed and the adsorbed Na exchanged by percolation with ammonium acetate (pH 7). The Na in this percolate is a measure for the CEC. Alternatively, after percolation with ammonium acetate, the sample can be washed free of excess salt, the whole sample distilled and the evolved ammonia determined. Percolation in tubes may also be replaced by shaking in flasks. Each extraction must be repeated three times and the three extracts should be combined for analysis. Note 1: Other procedures for CEC may be used provided the determination is done at pH 7. Note 2: In special cases where CEC is not a diagnostic criterion, e.g. saline and alkaline soils, the CEC may be determined at pH 8.2. Note 3: The base saturation of saline, calcareous and gypsiferous soils can be considered to be 100 percent. Note 4: Where low-activity clays are involved, the CEC of the organic matter has to be deducted. This can be done by the graphical method (FAO, 1966), or by analysing the CEC of the organic matter or the mineral colloids separately.
13. EXCHANGEABLE ACIDITY This is the acidity (H + Al) released upon exchange by an unbuffered 1 M KCl solution. It may also be designated actual acidity (as opposed to potential or extractable acidity). It is used to determine the so-called effective cation exchange capacity (ECEC) defined as: sum of bases + (H + Al), with bases being determined by ammonium acetate extraction. When the exchangeable acidity is substantial, the Al may be determined separately in the extract as it may be toxic to plants. Note: Because the contribution of H+ is often negligible, some laboratories only determine exchangeable Al. In that case, the ECEC is calculated as: sum of bases + Al.
14. EXTRACTABLE IRON, ALUMINIUM, MANGANESE AND SILICON These analyses comprise: ÿ Free Fe, Al and Mn compounds in the soil extracted by a dithionite-citrate solution. (Both the Mehra and Jackson and Holmgren procedures may be used.) ÿ Active, short-range-order or amorphous Fe, Al and silica compounds extracted by an acid oxalate solution. ÿ Organically bound Fe and Al extracted by a pyrophosphate solution.
15. SALINITY Attributes associated with salinity in soils are determined in the saturation extract. The attributes include: pH, electrical conductivity (ECe), sodium adsorption ratio (SAR) and the cations and anions of the dissolved salts. These include Ca, Mg, Na, K, carbonate and bicarbonate, chloride, nitrate and sulphate. The SAR and the exchangeable sodium percentage (ESP) may be estimated from the concentrations of the dissolved cations.
16. PHOSPHATE RETENTION The Blakemore procedure is used. The sample is equilibrated with a phosphate solution at pH 4.6 and the proportion of phosphate withdrawn from solution is determined. 327 126 World reference base for soil resources 2006
17. OPTICAL DENSITY OF OXALATE EXTRACT (ODOE) The sample is percolated or shaken with an acid ammonium oxalate solution. The optical density of the extract is measured at 430-nm wavelength.
18. MELANIC INDEX The sample is shaken with a 0.5 M NaOH solution and the absorbance of the extract is measured at 450 and 520 nm, respectively. The melanic index is obtained by dividing the absorbance at 450 nm by the absorbance at 520 nm.
19. MINERALOGICAL ANALYSIS OF THE SAND FRACTION After removal of cementing and coating materials, the sand is separated from the clay and silt by wet sieving. From the sand, the fraction 63–420 μm is separated by dry sieving. This fraction is divided into a heavy fraction and a light fraction with the aid of a high-density liquid: a solution of sodium polytungstate1 with a specific density of 2.85 kg dm-3. Of the heavy fraction, a microscopic slide is made; the light fraction is stained selectively for microscopic identification of feldspars and quartz. Volcanic glass can usually be recognized as isotropic grains with vesicles.
20. X-RAY DIFFRACTOMETRY The clay fraction is separated from the fine earth and deposited in an oriented fashion on glass slides or porous ceramic plates to be analysed on an X-ray diffractometer. Unoriented powder specimens of clay and other fractions are analysed on the same apparatus or with a Guinier X-ray camera (photographs).
1 Bromoform can also be used as high density liquid but its use is discouraged because of its highly toxic vapour. 328 127
Annex 2 Recommended codes for the reference soil groups, qualifiers and specifiers
Reference Soil Groups Acrisol AC Chernozem CH Kastanozem KS Podzol PZ Albeluvisol AB Cryosol CR Leptosol LP Regosol RG Alisol AL Durisol DU Lixisol LX Solonchak SC Andosol AN Ferralsol FR Luvisol LV Solonetz SN Anthrosol AT Fluvisol FL Nitisol NT Stagnosol ST Arenosol AR Gleysol GL Phaeozem PH Technosol TC Calcisol CL Gypsisol GY Planosol PL Umbrisol UM Cambisol CM Histosol HS Plinthosol PT Vertisol VR
Qualifiers Abruptic ap Duric du Gelistagnic gt Hypoluvic wl Aceric ae Dystric dy Geric gr Hyposalic ws Acric ac Ekranic ek Gibbsic gi Hyposodic wn Acroxic ao Endoduric nd Glacic gc Irragric ir Albic ab Endodystric ny Gleyic gl Lamellic ll Alcalic ax Endoeutric ne Glossalbic gb Laxic la Alic al Endofluvic nf Glossic gs Leptic le Aluandic aa Endogleyic ng Greyic gz Lignic lg Alumic au Endoleptic nl Grumic gm Limnic lm Andic an Endosalic ns Gypsic gy Linic lc Anthraquic aq Entic et Gypsiric gp Lithic li Anthric am Epidystric ed Haplic ha Lixic lx Arenic ar Epieutric ee Hemic hm Luvic lv Aric ai Epileptic el Histic hi Magnesic mg Aridic ad Episalic ea Hortic ht Manganiferric mf Arzic az Escalic ec Humic hu Mazic mz Brunic br Eutric eu Hydragric hg Melanic ml Calcaric ca Eutrosilic es Hydric hy Mesotrophic ms Calcic cc Ferralic fl Hydrophobic hf Mollic mo Cambic cm Ferric fr Hyperalbic ha Molliglossic mi Carbic cb Fibric fi Hyperalic hl Natric na Carbonatic cn Floatic ft Hypercalcic hc Nitic ni Chloridic cl Fluvic fv Hyperdystric hd Novic nv Chromic cr Folic fo Hypereutric he Nudilithic nt Clayic ce Fractipetric fp Hypergypsic hp Ombric om Colluvic co Fractiplinthic fa Hyperochric ho Ornithic oc Cryic cy Fragic fg Hypersalic hs Ortsteinic os Cutanic ct Fulvic fu Hyperskeletic hk Oxyaquic oa Densic dn Garbic ga Hypocalcic wc Pachic ph Drainic dr Gelic ge Hypogypsic wg Pellic pe
329 128 World reference base for soil resources 2006
Qualifiers (Continued) Petric pt Reductaquic ra Solodic sc Tidalic td Petrocalcic pc Reductic rd Sombric sm Toxic tx Petroduric pd Regic rg Spodic sd Transportic tn Petrogleyic py Rendzic rz Spolic sp Turbic tu Petrogypsic pg Rheic rh Stagnic st Umbric um Petroplinthic pp Rhodic ro Subaquatic sq Umbriglossic ug Petrosalic ps Rubic ru Sulphatic su Urbic ub Pisoplinthic px Ruptic rp Takyric ty Vermic vm Placic pi Rustic rs Technic te Vertic vr Plaggic pa Salic sz Tephric tf Vetic vt Plinthic pl Sapric sa Terric tr Vitric vi Posic po Silandic sn Thaptandic ba Voronic vo Profondic pf Siltic sl Thaptovitric bv Xanthic xa Protic pr Skeletic sk Thionic ti Yermic ye Puffi c pu Sodic so Thixotropic tp
Specifiers Bathy ..d Epi ..p Ortho ..o Thapto ..b Cumuli ..c Hyper ..h Para ..r Endo ..n Hypo ..w Proto ..t
330 WORLD SOIL RESOURCES REPORTS
1. Report of the First Meeting of the Advisory Panel on the Soil Map of the World, Rome, 19–23 June 1961 (E)** 2. Report of the First Meeting on Soil Survey, Correlation and Interpretation for Latin America, Rio de Janeiro, Brazil, 2831 May 1962 (E)** 3. Report of the First Soil Correlation Seminar for Europe, Moscow, USSR, 16–28 July 1962 (E)** 4. Report of the First Soil Correlation Seminar for South and Central Asia, Tashkent, Uzbekistan, USSR, 14 September–2 October 1962 (E)** 5. Report of the Fourth Session of the Working Party on Soil Classification and Survey (Subcommission on Land and Water Use of the European Commission on Agriculture), Lisbon, Portugal, 6–10 March 1963 (E)** 6. Report of the Second Meeting of the Advisory Panel on the Soil Map of the World, Rome, 9–11 July 1963 (E)** 7. Report of the Second Soil Correlation Seminar for Europe, Bucharest, Romania, 29 July–6 August 1963 (E)** 8. Report of the Third Meeting of the Advisory Panel on the Soil Map of the World, Paris, 3 January 1964 (E)** 9. Adequacy of Soil Studies in Paraguay, Bolivia and Peru, November–December 1963 (E)** 10. Report on the Soils of Bolivia, January 1964 (E)** 11. Report on the Soils of Paraguay, January 1964 (E)** 12. Preliminary Definition, Legend and Correlation Table for the Soil Map of the World, Rome, August 1964 (E)** 13. Report of the Fourth Meeting of the Advisory Panel on the Soil Map of the World, Rome, 16–21 May 1964 (E)** 14. Report of the Meeting on the Classification and Correlation of Soils from Volcanic Ash, Tokyo, Japan, 11–27 June 1964 (E)** 15. Report of the First Session of the Working Party on Soil Classification, Survey and Soil Resources of the European Commission on Agriculture, Florence, Italy, 1–3 October 1964 (E)** 16. Detailed Legend for the Third Draft on the Soil Map of South America, June 1965 (E)** 17. Report of the First Meeting on Soil Correlation for North America, Mexico, 1–8 February 1965 (E)** 18. The Soil Resources of Latin America, October 1965 (E)** 19. Report of the Third Correlation Seminar for Europe: Bulgaria, Greece, Romania, Turkey, Yugoslavia, 29 August–22 September 1965 (E)** 20. Report of the Meeting of Rapporteurs, Soil Map of Europe (Scale 1:1 000 000) (Working Party on Soil Classification and Survey of the European Commission on Agriculture), Bonn, Federal Republic of Germany, 29 November–3 December 1965 (E)** 21. Report of the Second Meeting on Soil Survey, Correlation and Interpretation for Latin America, Rio de Janeiro, Brazil, 13–16 July 1965 (E)** 22. Report of the Soil Resources Expedition in Western and Central Brazil, 24 June–9 July 1965 (E)** 23. Bibliography on Soils and Related Sciences for Latin America (1st edition), December 1965 (E)** 24. Report on the Soils of Paraguay (2nd edition), August 1964 (E)** 25. Report of the Soil Correlation Study Tour in Uruguay, Brazil and Argentina, June– August 1964 (E)** 26. Report of the Meeting on Soil Correlation and Soil Resources Appraisal in India, New Delhi, India, 5–15 April 1965 (E)** 331 27. Report of the Sixth Session of the Working Party on Soil Classification and Survey of the European Commission on Agriculture, Montpellier, France, 7–11 March 1967 (E)** 28. Report of the Second Meeting on Soil Correlation for North America, Winnipeg- Vancouver, Canada, 25 July–5 August 1966 (E)** 29. Report of the Fifth Meeting of the Advisory Panel on the Soil Map of the World, Moscow, USSR, 20–28 August 1966 (E)** 30. Report of the Meeting of the Soil Correlation Committee for South America, Buenos Aires, Argentina, 12–19 December 1966 (E)** 31. Trace Element Problems in Relation to Soil Units in Europe (Working Party on Soil Classification and Survey of the European Commission on Agriculture), Rome, 1967 (E)** 32. Approaches to Soil Classification, 1968 (E)** 33. Definitions of Soil Units for the Soil Map of the World, April 1968 (E)** 34. Soil Map of South America 1:5 000 000, Draft Explanatory Text, November 1968 (E)** 35. Report of a Soil Correlation Study Tour in Sweden and Poland, 27 September–14 October 1968 (E)** 36. Meeting of Rapporteurs, Soil Map of Europe (Scale 1:1 000 000) (Working Party on Soil Classification and Survey of the European Commission on Agriculture), Poitiers, France 21–23 June 1967 (E)** 37. Supplement to Definition of Soil Units for the Soil Map of the World, July 1969 (E)** 38. Seventh Session of the Working Party on Soil Classification and Survey of the European Commission on Agriculture, Varna, Bulgaria, 11–13 September 1969 (E)** 39. A Correlation Study of Red and Yellow Soils in Areas with a Mediterranean Climate (E)** 40. Report of the Regional Seminar of the Evaluation of Soil Resources in West Africa, Kumasi, Ghana, 14–19 December 1970 (E)** 41. Soil Survey and Soil Fertility Research in Asia and the Far East, New Delhi, 15–20 February 1971 (E)** 42. Report of the Eighth Session of the Working Party on Soil Classification and Survey of the European Commission on Agriculture, Helsinki, Finland, 5–7 July 1971 (E)** 43. Report of the Ninth Session of the Working Party on Soil Classification and Survey of the European Commission on Agriculture, Ghent, Belgium 28–31 August 1973 (E)** 44. First Meeting of the West African Sub-Committee on Soil Correlation for Soil Evaluation and Management, Accra, Ghana, 12–19 June 1972 (E)** 45. Report of the Ad Hoc Expert Consultation on Land Evaluation, Rome, Italy, 6–8 January 1975 (E)** 46. First Meeting of the Eastern African Sub-Committee for Soil Correlation and Land Evaluation, Nairobi, Kenya, 11–16 March 1974 (E)** 47. Second Meeting of the Eastern African Sub-Committee for Soil Correlation and Land Evaluation, Addis Ababa, Ethiopia, 25–30 October 1976 (E) 48. Report on the Agro-Ecological Zones Project, Vol. 1 – Methodology and Results for Africa, 1978. Vol. 2 – Results for Southwest Asia, 1978 (E) 49. Report of an Expert Consultation on Land Evaluation Standards for Rainfed Agriculture, Rome, Italy, 25–28 October 1977 (E) 50. Report of an Expert Consultation on Land Evaluation Criteria for Irrigation, Rome, Italy, 27 February–2 March 1979 (E) 51. Third Meeting of the Eastern African Sub-Committee for Soil Correlation and Land Evaluation, Lusaka, Zambia, 18–30 April 1978 (E) 52. Land Evaluation Guidelines for Rainfed Agriculture, Report of an Expert Consultation, 12–14 December 1979 (E)
332 53. Fourth Meeting of the West African Sub-Committee for Soil Correlation and Land Evaluation, Banjul, The Gambia, 20–27 October 1979 (E) 54. Fourth Meeting of the Eastern African Sub-Committee for Soil Correlation and Land Evaluation, Arusha, Tanzania, 27 October–4 November 1980 (E) 55. Cinquième réunion du Sous-Comité Ouest et Centre africain de corrélation des sols pour la mise en valeur des terres, Lomé, Togo, 7–12 décembre 1981 (F) 56. Fifth Meeting of the Eastern African Sub-Committee for Soil Correlation and Land Evaluation, Wad Medani, Sudan, 5–10 December 1983 (E) 57. Sixième réunion du Sous-Comité Ouest et Centre Africain de corrélation des sols pour la mise en valeur des terres, Niamey, Niger, 6–12 février 1984 (F) 58. Sixth Meeting of the Eastern African Sub-Committee for Soil Correlation and Land Evaluation, Maseru, Lesotho, 9–18 October 1985 (E) 59. Septième réunion du Sous-Comité Ouest et Centre africain de corrélation des sols pour la mise en valeur des terres, Ouagadougou, Burkina Faso, 10–17 novembre 1985 (F) 60. Revised Legend, Soil Map of the World, FAO-Unesco-ISRIC, 1988. Reprinted 1990 (E) 61. Huitième réunion du Sous-Comité Ouest et Centre africain de corrélation des sols pour la mise en valeur des terres, Yaoundé, Cameroun, 19–28 janvier 1987 (F) 62. Seventh Meeting of the East and Southern African Sub-Committee for Soil Correlation and Evaluation, Gaborone, Botswana, 30 March–8 April 1987 (E) 63. Neuvième réunion du Sous-Comité Ouest et Centre africain de corrélation des sols pour la mise en valeur des terres, Cotonou, Bénin, 14–23 novembre 1988 (F) 64. FAO-ISRIC Soil Database (SDB), 1989 (E) 65. Eighth Meeting of the East and Southern African Sub-Committee for Soil Correlation and Land Evaluation, Harare, Zimbabwe, 9–13 October 1989 (E) 66. World soil resources. An explanatory note on the FAO World Soil Resources Map at 1: 25 000 000 scale, 1991. Rev. 1, 1993 (E) 67. Digitized Soil Map of the World, Volume 1: Africa. Volume 2: North and Central America. Volume 3: Central and South America. Volume 4: Europe and West of the Urals. Volume 5: North East Asia. Volume 6: Near East and Far East. Volume 7: South East Asia and Oceania. Release 1.0, November 1991 (E) 68. Land Use Planning Applications. Proceedings of the FAO Expert Consultation 1990, Rome, 10–14 December 1990 (E) 69. Dixième réunion du Sous-Comité Ouest et Centre africain de corrélation des sols pour la mise en valeur des terres, Bouaké, Odienné, Côte d’Ivoire, 5–12 novembre 1990 (F) 70. Ninth Meeting of the East and Southern African Sub-Committee for Soil Correlation and Land Evaluation, Lilongwe, Malawi, 25 November – 2 December 1991 (E) 71. Agro-ecological land resources assessment for agricultural development planning. A case study of Kenya. Resources data base and land productivity. Main Report. Technical Annex 1: Land resources. Technical Annex 2: Soil erosion and productivity. Technical Annex 3: Agro-climatic and agro-edaphic suitabilities for barley, oat, cowpea, green gram and pigeonpea. Technical Annex 4: Crop productivity. Technical Annex 5: Livestock productivity. Technical Annex 6: Fuelwood productivity. Technical Annex 7: Systems documentation guide to computer programs for land productivity assessments. Technical Annex 8: Crop productivity assessment: results at district level. 1991. Main Report 71/9: Making land use choices for district planning, 1994 (E) 72. Computerized systems of land resources appraisal for agricultural development, 1993 (E) 73. FESLM: an international framework for evaluating sustainable land management, 1993 (E) 74. Global and national soils and terrain digital databases (SOTER), 1993. Rev. 1, 1995 (E) 75. AEZ in Asia. Proceedings of the Regional Workshop on Agro-ecological Zones Methodology and Applications, Bangkok, Thailand, 17–23 November 1991 (E) 333 76. Green manuring for soil productivity improvement, 1994 (E) 77. Onzième réunion du Sous-Comité Ouest et Centre africain de corrélation des sols pour la mise en valeur des terres, Ségou, Mali, 18–26 janvier 1993 (F) 78. Land degradation in South Asia: its severity, causes and effects upon the people, 1994 (E) 79. Status of sulphur in soils and plants of thirty countries, 1995 (E) 80. Soil survey: perspectives and strategies for the 21st century, 1995 (E) 81. Multilingual soil database, 1995 (Multil) 82. Potential for forage legumes of land in West Africa, 1995 (E) 83. Douzième réunion du Sous-Comité Ouest et Centre africain de corrélation des sols pour la mise en valeur des terres, Bangui, République Centrafricain, 5–10 décembre 1994 (F) 84. World reference base for soil resources, 1998 (E) 85. Soil Fertility Initiative for sub-Saharan Africa, 1999 (E) 86. Prevention of land degradation, enhancement of carbon sequestration and conservation of biodiversity through land use change and sustainable land management with a focus on Latin America and the Caribbean, 1999 (E) 87. AEZWIN: An interactive multiple-criteria analysis tool for land resources appraisal, 1999 (E)
88. Sistemas de uso de la tierra en los trópicos húmedios y la emisión y secuestro de CO2, 2000 (S) 89. Land resources information systems for food security in SADC countries, 2000 (E) 90. Land resource potential and constraints at regional and country levels, 2000 (E) 91. The European soil information system, 2000 (E) 92. Carbon sequestration projects under the clean development mechanism to address land degradation, 2000 (E) 93. Land resources information systems in Asia, 2000 (E) 94. Lecture notes on the major soils of the world, 2001 (E) 95. Land resources information systems in the Caribbean, 2001 (E) 96. Soil carbon sequestration for improved land management, 2001 (E F S) 97. Land degradation assessment in drylands – LADA project, 2002 (E) 98. Quatorzième réunion du Sous-Comité Ouest et Centre africain de corrélation des sols pour la mise en valeur des terres, Abomey, Bénin, 9–13 octobre 2000, 2002 (F) 99. Land resources information systems in the Near East, 2002 (E) 100. Data sets, indicators and methods to assess land degradation in drylands, 2003 (E) 101. Biological management of soil ecosystems for sustainable agriculture, 2003 (E) 102. Carbon sequestration in dryland soils, 2004 (E) 103 World reference base for soil resources 2006 – A framework for international classification, correlation and communication, 2006 (E)
Availability: June 2006
E – English Multil – Multilingual F – French ** Out of print S – Spanish
334 Food and Agriculture Organization of the United Nations (2007) IUSS Working Group WRB. World reference base for soil resources 2006. First update 2007. World Soil Resources Reports 103. http://www.fao.org/fileadmin/templates/nr/images/resources/pdf_ documents/wrb2007_red.pdf reproduced with permission
335 iii
Contents page ACKNOWLEDGEMENTS FOREWORD LIST OF ACRONYMS LIST OF ACRONYMS 1. BACKGROUND TO THE WORLD REFERENCE BASE FOR SOIL RESOURCES History From its beginnings to the first edition in 1998 From the first edition in 1998 to the second edition in 2006 Basic principles Architecture Key to the Reference Soil Groups The qualifier level Principles and use of the qualifiers in the WRB The geographical dimension of WRB qualifiers – match to mapping scale The object classified in the WRB Rules for classification 2. DIAGNOSTIC HORIZONS, PROPERTIES AND MATERIALS Diagnostic horizons Albic horizon Anthraquic horizon Anthric horizon Argic horizon Calcic horizon Cambic horizon Cryic horizon Duric horizon Ferralic horizon Ferric horizon Folic horizon Fragic horizon Fulvic horizon Gypsic horizon Histic horizon Hortic horizon Hydragric horizon Irragric horizon Melanic horizon Mollic horizon Natric horizon Nitic horizon Petrocalcic horizon Petroduric horizon Petrogypsic horizon Petroplinthic horizon Pisoplinthic horizon Plaggic horizon Plinthic horizon Salic horizon
336 iv
Sombric horizon Spodic horizon Takyric horizon Terric horizon Thionic horizon Umbric horizon Vertic horizon Voronic horizon Yermic horizon Diagnostic properties Abrupt textural change Albeluvic tonguing Andic properties Aridic properties Continuous rock Ferralic properties Geric properties Gleyic colour pattern Lithological discontinuity Reducing conditions Secondary carbonates Stagnic colour pattern Vertic properties Vitric properties Diagnostic materials Artefacts Calcaric material Colluvic material Fluvic material Gypsiric material Limnic material Mineral material Organic material Ornithogenic material Sulphidic material Technic hard rock Tephric material 3. KEY TO THE REFERENCE SOIL GROUPS OF THE WRB WITH LISTS OF PREFIX AND SUFFIX QUALIFIERS 4. DESCRIPTION, DISTRIBUTION, USE AND MANAGEMENT OF REFERENCE SOIL GROUPS Acrisols Albeluvisols Alisols Andosols Anthrosols Arenosols Calcisols Cambisols Chernozems Cryosols Durisols
337 v
Ferralsols Fluvisols Gleysols Gypsisols Histosols Kastanozems Leptosols Lixisols Luvisols Nitisols Phaeozems Planosols Plinthosols Podzols Regosols Solonchaks Solonetz Stagnosols Technosols Umbrisols Vertisols 5. DEFINITIONS OF FORMATIVE ELEMENTS FOR SECOND-LEVEL UNITS OF THE WRB REFERENCES ANNEXES: 1. SUMMARY OF ANALYTICAL PROCEDURES FOR SOIL CHARACTERIZATION 2. RECOMMENDED CODES FOR THE REFERENCE SOIL GROUPS, QUALIFIERS AND SPECIFIERS
338 vi
List of tables page 1. Rationalized Key to the WRB Reference Soil Groups 2. Prefix and suffix qualifiers in the WRB – case of Cryosols
339 vii
Acknowledgements
The text of this publication is based on numerous valuable contributions from hundreds of soil scientists worldwide. They participated in field tours, workshops and conferences; they sent comments, and they tested the World Reference Base for Soil Resources (WRB) approach. This publication would not have been possible without the support of a number of international institutes and organizations, notably the Food and Agriculture Organization of the United Nations (FAO), the National Resources Conservation Service of the United States of America, the European Soils Bureau hosted by the Joint Research Centre of the European Commission, the West and Central African Union of Soil Scientists Association, and the International Soil Reference and Information Centre (ISRIC) – World Soil Information, to name only the major ones. Last but not least, the Working Group World Reference Base of the International Union of Soil Sciences (IUSS) was supported by other IUSS working groups, in particular the Soils in Urban, Industrial, Traffic and Mining Areas Working Group and the Cryosol Working Group of the IUSS/International Permafrost Association. National soil institutes in many countries assisted in WRB field tours, and organized conferences and WRB summer schools (listed in Chapter 1). This edition has been edited by Erika Michéli (Szent István University, Hungary), Peter Schad (Technische Universität München, Germany) and Otto Spaargaren (ISRIC – World Soil Information, Netherlands). Particular mention should go to Richard Arnold (United States of America), Hans-Peter Blume (Germany) and Rudi Dudal (Belgium). They were involved from the inception of the International Reference Base, more than 25 years ago, and have provided invaluable institutional memory for the objectives and approach. The Working Group wishes to express its gratitude to FAO for its support and for making possible the printing and distribution of this publication.
340 viii
Foreword
The first official version of the World Reference Base for Soil Resources (WRB) was released at the 16th World Congress of Soil Science at Montpellier in 1998. At the same event, it was also endorsed and adopted as the system for soil correlation and international communication of the International Union of Soil Sciences (IUSS). After eight years of intensive worldwide testing and data collection, the current state-of-the- art of the WRB is presented. This publication reflects the valuable work of the authors of the earlier drafts and the first version of the WRB, as well as the experiences and contributions of many soil scientists who participated in the work of the IUSS Working Group on the WRB. Globalization and global environmental issues necessitate harmonization and correlation of technical languages, such as the one used in soil science. It is hoped that this publication will contribute to the understanding of soil science in the public debate and in the scientific community. The publication has been made possible by the sustained efforts of a large group of expert authors, and the cooperation and logistic support of the IUSS, the International Soil Reference and Information Centre (ISRIC) and the Food and Agriculture Organization of the United Nations (FAO).
Erika Michéli (Chair), Peter Schad (Vice-Chair) and Otto Spaargaren (Secretary) IUSS Working Group WRB
David Dent ISRIC – World Soil Information
Freddy Nachtergaele Land and Water Development Division Food and Agriculture Organization of the United Nations (FAO)
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List of acronyms
Al Aluminium Ca Calcium CaCO3 Calcium carbonate CEC Cation exchange capacity COLE Coefficient of linear extensibility EC Electrical conductivity ECe Electrical conductivity of saturation extract ECEC Effective CEC ESP Exchangeable sodium percentage FAO Food and Agriculture Organization of the United Nations Fe Iron HCl Hydrochloric acid IRB International Reference Base for Soil Classification ISRIC International Soil Reference and Information Centre ISSS International Society of Soil Science IUSS International Union of Soil Sciences K Potassium KOH Potassium hydroxide Mg Magnesium Mn Manganese N Nitrogen Na Sodium NaOH Sodium hydroxide ODOE Optical density of the oxalate extract P Phosphorus RSG Reference Soil Group S Sulphur SAR Sodium adsorption ratio SiO2 Silica SUITMA Soils in Urban, Industrial, Traffic and Mining Areas (special working group) Ti Titanium TRB Total reserve of bases UNEP United Nations Environment Programme UNESCO United Nations Educational, Scientific, and Cultural Organization USDA United States Department of Agriculture WRB World Reference Base for Soil Resources Zn Zinc
342 343 1
Chapter 1 Background to the World Reference Base for Soil Resources
HISTORY From its beginnings to the first edition in 1998 In the early 1980s, countries became increasingly interdependent for their supplies of food and agricultural products. Problems of land degradation, disparity of production potentials and of population-carrying capacities became international concerns that required harmonized soil information. Against this background, the Food and Agriculture Organization of the United Nations (FAO) felt that a framework should be created through which existing soil classification systems could be correlated and harmonized. Concurrently, it would serve as an international means of communication and for exchange of experience. The elaboration of such a framework required a more active involvement of the entire soils community. At the initiative of FAO, the United Nations Educational, Scientific, and Cultural Organization (UNESCO), the United Nations Environment Programme (UNEP), and the International Society of Soil Science (ISSS), a group of soil scientists representing a broad range of soil institutions met in Sofia, Bulgaria, in 1980 and 1981 to enhance international involvement in a follow-up to the Soil Map of the World (FAO–UNESCO, 1971–1981). The meeting was hosted by the Poushkarov Institute of Soil Science and Yield Programming. The meeting decided to launch a programme to develop an International Reference Base for Soil Classification (IRB) with the aim to reach agreement on the major soil groupings to be recognized at a global scale, as well as on the criteria to define and separate them. It was expected that such an agreement would facilitate the exchange of information and experience, provide a common scientific language, strengthen the applications of soil science, and enhance communication with other disciplines. The group met in 1981 for a second time at Sofia and laid down the general principles of a joint programme towards the development of an IRB. In 1982, the 12th Congress of the ISSS, in New Delhi, India, endorsed and adopted this programme. The work was conducted by a newly created IRB working group, chaired by E. Schlichting with R. Dudal serving as secretary. At the 13th Congress of the ISSS, in Hamburg, Germany, in 1986, the IRB programme was entrusted to Commission V, with A. Ruellan as chair and R. Dudal as secretary. These charges were continued through the 14th Congress of the ISSS, in Kyoto, Japan, in 1990. In 1992, the IRB was renamed the World Reference Base for Soil Resources (WRB). Hence, a WRB working group was established at the 15th Congress of the ISSS, in Acapulco, Mexico, in 1994, with J. Deckers, F. Nachtergaele and O. Spaargaren as chair, vice-chair and secretary, respectively, through the 16th Congress of the ISSS, in Montpellier, France, in 1998. At the 17th World Congress of Soil Science, in Bangkok, Thailand, in 2002, the leadership for the WRB programme was entrusted to E. Michéli, P. Schad and O. Spaargaren as chair, vice-chair and secretary, respectively. At a meeting of the IRB Working Group in Montpellier in 1992, it was decided that the revised FAO–UNESCO legend would form the basis for the further development of the IRB and that efforts were to be merged. It would be the task of the IRB to apply its general principles to the further refinement of the FAO–UNESCO units and to provide them with the necessary depth and validation.
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Progress in the preparation of the WRB was reported to the 15th Congress of the ISSS at Acapulco in 1994 (FAO, 1994). Numerous contributions were received from soil scientists; the WRB was discussed and tested in meetings and excursions at Leuven, Belgium (1995), Kiel, Germany (1995), Moscow, Russian Federation (1996), South Africa (1996), Argentina (1997) and Vienna, Austria (1997). The first official text of the WRB was presented at the 16th World Congress of Soil Science in Montpellier in 1998 in three volumes: 1. World Reference Base for Soil Resources. An introduction. 2. World Reference Base for Soil Resources. Atlas. 3. World Reference Base for Soil Resources. The WRB text was then adopted by the ISSS Council as the officially recommended terminology to name and classify soils. By general agreement, it was then decided that the text would remain unchanged for at least eight years, but that it would be tested extensively during this period and a revision proposed at the 18th World Congress of Soil Science in 2006. From the first edition in 1998 to the second edition in 2006 In the period 1998–2006, the WRB became the official reference soil nomenclature and soil classification for the European Commission and was adopted by the West and Central African Soil Science Association as the preferred tool to harmonize and exchange soil information in the region. The main text was translated in 13 languages (Chinese, French, German, Hungarian, Italian, Japanese, Latvian, Lithuanian, Polish, Rumanian, Russian, Spanish and Vietnamese) and adopted as a higher level of the national soil classification system in a number of countries (e.g. Italy, Mexico, Norway, Poland and Viet Nam). The text was further illustrated by lecture notes and a CD-ROM on the major soils of the world (FAO, 2001a and 2001b) and a World Soil Resources Map at a scale 1:25 000 000 by the Joint Research Centre, FAO and the International Soil Reference and Information Centre (ISRIC) in 2002. A Web site was established (http://www.fao.org/landandwater/agll/wrb/default.stm) and a newsletter was distributed to hundreds of soil scientists. Specific attention was paid to land-use and soil management issues for tropical and dryland soils using WRB information (FAO, 2003 and 2005). Numerous articles appeared in peer-reviewed soil science journals and books, suggesting improvements to the system. Two conferences were held together with field trips: in 2001 in Velence (Hungary, organized by the Szent István University in Gödöllö); and in 2004 in Petrozavodsk (Russian Federation, organized by the Institute of Biology, Karelian Research Centre). At the same time, a number of field excursions were organized to test and refine the WRB approach in the field: Burkina Faso and Côte d’Ivoire (1998); Viet Nam and China (1998); Italy (1999); Georgia (2000); Ghana and Burkina Faso (2001); Hungary (2001); South Africa and Namibia (2003); Poland (2004); Italy (2004); Russian Federation (2004); Mexico (2005); Kenya and the United Republic of Tanzania (2005); and Ghana (2005). Summer schools, coordinated by E. Michéli (Hungary), were organized under the auspices of the EU Joint Research Centre in Ispra, Italy (2003 and 2004), and in Gödöllö, Hungary (2005), to teach the system to soil science students and practitioners. In the same period, the European Commission issued the Soil Atlas of Europe based on the WRB (European Soil Bureau Network/European Commission, 2005). A major effort was undertaken to harmonize nomenclature with the Soil Taxonomy of the United States Department of Agriculture (USDA) and other major national soil classification systems. Some national classifications took up elements of the WRB, e.g. the Chinese soil taxonomy (CRGCST, 2001), the Czech soil classification (Nĕmeček et al., 2001), the Lithuanian soil classification (Buivydaité et al., 2001), and the Russian soil classification system (Shishov et al., 2001). A WRB e-mail forum was organized in 2005 to enable finalization of suggestions for each Soil Reference Soil Group. Independently, special working groups of the International Union of Soil Sciences (IUSS) (formerly the ISSS), such as the ones on Cryosols and on Soils in Urban, Industrial, Traffic and Mining Areas (SUITMA) proposed changes to the system, some of which have been adopted in the present text.
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The second edition of the WRB has undergone a major revision. Technosols and Stagnosols have been introduced, leading to 32 Reference Soil Groups (RSGs) instead of 30. The Technosols are soils with a certain amount of artefacts, a constructed geomembrane or technic hard rock. The Stagnosols unify the former Epistagnic subunits of many other RSGs. Some re- arrangement has taken place in the order of the key, with Anthrosols, Solonetz, Nitisols and Arenosols moving upwards. The definitions of many diagnostic soil horizons, soil properties, and materials have been adjusted. The qualifiers are now subdivided into prefix and suffix ones. Prefix qualifiers comprise those that are typically associated with the RSG (in order of their importance) and the intergrades to other RSGs (in order of the key). All other qualifiers are listed as suffix qualifiers. BASIC PRINCIPLES The general principles on which the WRB is based were laid down during the early Sofia meetings in 1980 and 1981, and further elaborated upon by the working groups entrusted with its development. These general principles can be summarized as follows: • The classification of soils is based on soil properties defined in terms of diagnostic horizons, properties and materials, which to the greatest extent possible should be measurable and observable in the field. • The selection of diagnostic characteristics takes into account their relationship with soil forming processes. It is recognized that an understanding of soil-forming processes contributes to a better characterization of soils but that they should not, as such, be used as differentiating criteria. • To the extent possible at a high level of generalization, diagnostic features are selected that are of significance for soil management. • Climate parameters are not applied in the classification of soils. It is fully realized that they should be used for interpretation purposes, in dynamic combination with soil properties, but they should not form part of soil definitions. • The WRB is a comprehensive classification system that enables people to accommodate their national classification system. It comprises two tiers of categorical detail: − the Reference Base, limited to the first level only and having 32 RSGs; − the WRB Classification System, consisting of combinations of a set of prefix and suffix qualifiers that are uniquely defined and added to the name of the RSG, allowing very precise characterization and classification of individual soil profiles. • Many RSGs in the WRB are representative of major soil regions so as to provide a comprehensive overview of the world’s soil cover. • The Reference Base is not meant to substitute for national soil classification systems but rather to serve as a common denominator for communication at an international level. This implies that lower-level categories, possibly a third category of the WRB, could accommodate local diversity at country level. Concurrently, the lower levels emphasize soil features that are important for land use and management. • The Revised Legend of the FAO/UNESCO Soil Map of the World (FAO, 1988) has been used as a basis for the development of the WRB in order to take advantage of international soil correlation that has already been conducted through this project and elsewhere. • The first edition of the WRB, published in 1998, comprised 30 RSGs; the second edition, published in 2006, has 32 RSGs. • Definitions and descriptions of soil lower level units reflect variations in soil characteristics both vertically and laterally so as to account for spatial linkages within the landscape. • The term Reference Base is connotative of the common denominator function that the WRB assumes. Its units have sufficient width to stimulate harmonization and correlation of existing national systems.
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• In addition to serving as a link between existing classification systems, the WRB also serves as a consistent communication tool for compiling global soil databases and for the inventory and monitoring of the world’s soil resources. • The nomenclature used to distinguish soil groups retains terms that have been used traditionally or that can be introduced easily in current language. They are defined precisely in order to avoid the confusion that occurs where names are used with different connotations. Although the basic framework of the FAO Legend (with its two categorical levels and guidelines for developing classes at a third level) was adopted, it has been decided to merge the lower levels. Each RSG of the WRB is provided with a listing of possible prefix and suffix qualifiers in a priority sequence, from which the user can construct the second-level units. The broad principles that govern the WRB class differentiation are: • At the higher categorical level, classes are differentiated mainly according to the primary pedogenetic process that has produced the characteristic soil features, except where special soil parent materials are of overriding importance. • At the second level, soil units are differentiated according to any secondary soil-forming process that has affected the primary soil features significantly. In certain cases, soil characteristics that have a significant effect on use may be taken into account. It is recognized that a number of RSGs may occur under different climate conditions. However, it was decided not to introduce separations on account of climate characteristics so that the classification of soils is not subordinated to the availability of climate data. ARCHITECTURE Currently, the WRB comprises two tiers of categorical detail: 1. Tier 1: The RSGs, comprising 32 RSGs; 2. Tier 2: The combination of a RSGs with qualifiers, detailing the properties of the RSGs by adding a set of uniquely defined qualifiers. Key to the Reference Soil Groups The Key to the RSGs in the WRB stems from the Legend of the Soil Map of the World. The history behind the Key to the Major Soil Units of the Legend of the Soil Map of the World reveals that it is mainly based on functionality; the Key was conceived to derive the correct classification as efficiently as possible. The sequence of the Major Soil Units was such that the central concept of the major soils would come out almost automatically by specifying briefly a limited number of diagnostic horizons, properties or materials. Table 1 provides an overview and logic for the sequence of the RSGs in the WRB Key. The RSGs are allocated to sets on the basis of dominant identifiers, i.e. the soil-forming factors or processes that most clearly condition the soil formation. The sequencing of the groups is done according to the following principles: 1. First, organic soils key out to separate them from mineral soils (Histosols). 2. The second major distinction in the WRB is to recognize human activity as a soil- forming factor, hence the position of the Anthrosols and Technosols after the Histosols; it also appears logical to key out the newly-introduced Technosols close to the beginning of the Key, for the following reasons: − one can almost immediately key out soils that should not be touched (toxic soils that should be handled by experts); − a homogeneous group of soils in strange materials is obtained; − politicians and decision-makers who consult the Key will immediately encounter these problematic soils. 3. Next are the soils with a severe limitation to rooting (Cryosols and Leptosols). 4. Then comes a group of RSGs that are or have been strongly influenced by water: Vertisols, Fluvisols, Solonetz, Solonchaks, and Gleysols.
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5. The following set of soil groups are the RSGs in which iron (Fe) and/or aluminium (Al) chemistry plays a major role in their formation: Andosols, Podzols, Plinthosols, Nitisols and Ferralsols. 6. Next comes a set of soils with perched water: Planosols and Stagnosols. 7. The next grouping comprises soils that occur predominantly in steppe regions and have humus-rich topsoils and a high base saturation: Chernozems, Kastanozems and Phaeozems. 8. The next set comprises soils from the drier regions with accumulation of gypsum (Gypsisols), silica (Durisols) or calcium carbonate (Calcisols). 9. Then comes a set of soils with a clay-rich subsoil: Albeluvisols, Alisols, Acrisols, Luvisols and Lixisols. 10. Finally, relatively young soils or soils with very little or no profile development, or very homogenous sands, are grouped together: Umbrisols, Arenosols, Cambisols and Regosols. TABLE 1 Rationalized Key to the WRB Reference Soil Groups 1. Soils with thick organic layers: Histosols 2. Soils with strong human influence Soils with long and intensive agricultural use: Anthrosols Soils containing many artefacts: Technosols 3. Soils with limited rooting due to shallow permafrost or stoniness Ice-affected soils: Cryosols Shallow or extremely gravelly soils: Leptosols 4. Soils influenced by water Alternating wet-dry conditions, rich in swelling clays: Vertisols Floodplains, tidal marshes: Fluvisols Alkaline soils: Solonetz Salt enrichment upon evaporation: Solonchaks Groundwater affected soils: Gleysols 5. Soils set by Fe/Al chemistry Allophanes or Al-humus complexes: Andosols Cheluviation and chilluviation: Podzols Accumulation of Fe under hydromorphic conditions: Plinthosols Low-activity clay, P fixation, strongly structured: Nitisols Dominance of kaolinite and sesquioxides: Ferralsols 6. Soils with stagnating water Abrupt textural discontinuity: Planosols Structural or moderate textural discontinuity: Stagnosols 7. Accumulation of organic matter, high base status Typically mollic: Chernozems Transition to drier climate: Kastanozems Transition to more humid climate: Phaeozems 8. Accumulation of less soluble salts or non-saline substances Gypsum: Gypsisols Silica: Durisols Calcium carbonate: Calcisols 9. Soils with a clay-enriched subsoil Albeluvic tonguing: Albeluvisols Low base status, high-activity clay: Alisols Low base status, low-activity clay: Acrisols High base status, high-activity clay: Luvisols High base status, low-activity clay: Lixisols 10. Relatively young soils or soils with little or no profile development With an acidic dark topsoil: Umbrisols
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Sandy soils: Arenosols Moderately developed soils: Cambisols Soils with no significant profile development: Regosols The qualifier level In the WRB, a distinction is made between typically associated qualifiers, intergrades and other qualifiers. Typically associated qualifiers are referred to in the Key to the particular RSGs, e.g. Hydragric or Plaggic for the Anthrosols. Intergrade qualifiers are those that reflect important diagnostic criteria of another RSG. The WRB Key will, in that case, dictates the choice of the RSG and the intergrade qualifier in that case provides the bridge to the other RSG. Other qualifiers are those not typically associated with an RSG and that do not link to other RSGs, e.g. Geric or Posic for Ferralsols. This group reflects characteristics such as colour, base status, and other chemical and physical properties provided that they are not used as a typically associated qualifier in that particular group. Principles and use of the qualifiers in the WRB A two-tier system is used for the qualifier level, comprising: • Prefix qualifiers: typically associated qualifiers and intergrade qualifiers; the sequence of the intergrade qualifiers follows that of the RSGs in the WRB Key, with the exception of Arenosols; this intergrade is ranked with the textural suffix qualifiers (see below). Haplic closes the prefix qualifier list indicating that neither typically associated nor intergrade qualifiers apply. • Suffix qualifiers: other qualifiers, sequenced as follows: (1) qualifiers related to diagnostic horizons, properties or materials; (2) qualifiers related to chemical characteristics; (3) qualifiers related to physical characteristics; (4) qualifiers related to mineralogical characteristics; (5) qualifiers related to surface characteristics; (6) qualifiers related to textural characteristics, including coarse fragments; (7) qualifiers related to colour; and (8) remaining qualifiers. • Table 2 provides an example of the listing of prefix and suffix qualifiers. TABLE 2 Prefix and suffix qualifiers in the WRB – case of Cryosols Prefix qualifiers Suffix qualifiers Glacic Gypsiric Turbic Calcaric Folic Ornithic* Histic Dystric Technic Eutric Hyperskeletic Reductaquic* Leptic Oxyaquic Natric Thixotropic Salic Aridic Vitric Skeletic Spodic Arenic Mollic Siltic Calcic Clayic* Umbric Drainic* Cambic Transportic* Haplic Novic* * = newly introduced qualifiers Examples: 1. Histic Turbic Cryosol (Reductaquic, Dystric). 2. Haplic Cryosol (Aridic, Skeletic).
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Prefix qualifier names are always put before the RSG name; suffix qualifier names are always placed between brackets following the RSG name. Combinations of qualifiers that indicate a similar status or duplicate each other are not permitted, such as combinations of Thionic and Dystric, Calcaric and Eutric, or Rhodic and Chromic. Specifiers such as Epi-, Endo-, Hyper-, Hypo-, Thapto-, Bathy-, Para-, Proto-, Cumuli- and Ortho- are used to indicate a certain expression of the qualifier. When classifying a soil profile, all applying qualifiers of the listing must be recorded. For mapping purposes, the scale will determine the number of qualifiers used. In that case, prefix qualifiers have priority over the suffix qualifiers. The qualifier listing for each RSG accommodates most cases. Where not listed qualifiers are needed, the cases should be documented and reported to the WRB Working Group. The geographical dimension of WRB qualifiers – match to mapping scale The WRB was not designed originally for mapping soils but its roots are in the Legend of the Soil Map of the World. Before the WRB came into existence, the FAO Legend was used for soil mapping at various scales, and rather successfully (e.g. soil mapping in Bangladesh, Botswana, Ethiopia, the European Union, Kenya, and the United Republic of Tanzania). Whether desirable or not, people are using the WRB as a tool for soil mapping (e.g. 1:1 000 000 scale Soil Map of Europe; 1:250 000 Soil Map of the Central Highlands of Viet Nam). A basic principle in soil mapping is that the soil surveyor designs the legend of the map so as to best suit the purpose of the survey. If the WRB is designed to support small-scale mapping of the global soil landscapes, it would be advantageous to have a structure that lends itself to support such overview maps. Hence, the discussion on the qualifier listings should not be held in isolation of the overview maps of the soils of the world or the continents in the WRB. Therefore, it is suggested that the WRB qualifiers be linked to small-scale soil maps as follows: • only prefix qualifiers for mapping between 1/5*106 and 1/106 scale; • additionally suffix qualifiers for mapping between 1/106 and 1/250*103 scale. For larger mapping scales, it is suggested that, in addition, national or local soil classification systems be used. They are designed to accommodate local soil variability, which can never be accounted for in a world reference base. THE OBJECT CLASSIFIED IN THE WRB Like many common words, the word soil has several meanings. In its traditional meaning, soil is the natural medium for the growth of plants, whether or not it has discernible soil horizons (Soil Survey Staff, 1999). In the 1998 WRB, soil was defined as: “… a continuous natural body which has three spatial and one temporal dimension. The three main features governing soil are: • It is formed by mineral and organic constituents and includes solid, liquid and gaseous phases. • The constituents are organized in structures, specific for the pedological medium. These structures form the morphological aspect of the soil cover, equivalent to the anatomy of a living being. They result from the history of the soil cover and from its actual dynamics and properties. Study of the structures of the soil cover facilitates perception of the physical, chemical and biological properties; it permits understanding the past and present of the soil, and predicting its future. • The soil is in constant evolution, thus giving the soil its fourth dimension, time.” Although there are good arguments to limit soil survey and mapping to identifiable stable soil areas with a certain thickness, the WRB has taken the more comprehensive approach to name any object forming part of the epiderm of the earth (Nachtergaele, 2005). This approach has a number of advantages, notably that it allows tackling environmental problems in a systematic and holistic way and avoids sterile discussions on a universally agreed definition of soil and its required thickness and stability. Therefore, the object classified in the WRB is: any material within 2 m from the Earth’s surface that is in contact with the atmosphere, with the
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exclusion of living organisms, areas with continuous ice not covered by other material, and water bodies deeper than 2 m1. The definition includes continuous rock, paved urban soils, soils of industrial areas, cave soils as well as subaqueous soils. Soils under continuous rock, except those that occur in caves, are generally not considered for classification. In special cases, the WRB may be used to classify soils under rock, e.g. for palaeopedological reconstruction of the environment. The lateral dimension of the object classified should be large enough to represent the nature of any horizon and variability that may be present. The minimum horizontal area may range from 1 to 10 m2 depending on the variability of the soil cover. RULES FOR CLASSIFICATION Classification consists of three steps. Step one The expression, thickness and depth of layers are checked against the requirements of WRB diagnostic horizons, properties and materials, which are defined in terms of morphology and/or analytical criteria (Chapter 2). Where a layer fulfils the criteria of more than one diagnostic horizon, property or material, they are regarded as overlapping or coinciding. Step two The described combination of diagnostic horizons, properties and materials is compared with the WRB Key (Chapter 3) in order to find the RSG, which is the first level of WRB classification. The user should go through the Key systematically, starting at the beginning and excluding one by one all RSGs for which the specified requirements are not met. The soil belongs to the first RSG for which it meets all specified requirements. Step three For the second level of WRB classification, qualifiers are used. The qualifiers are listed in the Key with each RSG as prefix and suffix qualifiers. Prefix qualifiers comprise those that are typically associated to the RSG and the intergrades to other RSGs. All other qualifiers are listed as suffix qualifiers. For classification at the second level, all applying qualifiers have to be added to the name of the RSG. Redundant qualifiers (the characteristics of which are included in a previously set qualifier) are not added. The prefix qualifiers are added before the name of the RSG without brackets and without commas. The sequence is from right to left, i.e. the uppermost qualifier in the list stands closest to the name of the RSG. The suffix qualifiers are added in brackets after the name of the RSG and are separated from each other with commas. The sequence is from left to right according to the top-down sequence in the qualifiers list. See example below. Specifiers can be used to indicate the degree of expression of qualifiers. Buried layers that relate to diagnostic horizons, properties and materials, can be indicated by the Thapto- specifier, which can be used with any applying qualifier, listed in Chapter 5, even if the qualifier is not mentioned in the specific list of qualifiers for the respective RSG in Chapter 3. In that case, Thapto... is added as the last suffix qualifier.
Where a soil is buried under new material, the following rules apply: 1. The overlying new material and the buried soil are classified as one soil if both together qualify as Histosol, Technosol, Cryosol, Leptosol, Vertisol, Fluvisol, Gleysol, Andosol, Planosol, Stagnosol or Arenosol. 2. Otherwise, the new material is classified at the first level if the new material is 50 cm or more thick or if the new material, if it stood alone, fits the requirements of a RSG other than a Regosol.. 3. In all other cases, the buried soil is classified at the first level.
1 In tidal areas, the depth of 2 m is to be applied at low tide.
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4. If the overlying soil is classified at the first level, the name of the buried soil is recognized with the Thapto- specifier and -ic added to the RSG name of the buried soil. The whole is placed in brackets after the name of the overlying soil adding the word “over” in between, e.g. Technic Umbrisol (Greyic) over (Rustic Thapto-Podzolic (Skeletic). If the buried soil is classified at the first level, the overlying material is indicated with the Novic qualifier.
It is recommended that the Guidelines for Soil Description (FAO, 2006) be used to describe the soil and its features. It is useful to list the occurrence and depth of diagnostic horizons, properties and materials identified. The field classification provides a preliminary assessment using all observable or easily measurable properties and features of the soil and associated terrain. The final classification is made when analytical data are available. It is recommended that Procedures for Soil Analysis (Van Reeuwijk, 2006) is followed in determining chemical and physical characteristics. A summary of these is included in Annex 1. Example of WRB soil classification A soil has a ferralic horizon; texture in the upper part of the ferralic horizon changes from sandy loam to sandy clay within 15 cm. The pH is between 5.5 and 6, indicating moderate to high base saturation. The B horizon is dark red; below 50 cm, mottling occurs. The field classification of this soil is: Lixic Ferralsol (Ferric, Rhodic). If subsequent laboratory analysis reveals that the -1 cation exchange capacity (CEC) of the ferralic horizon is less than 4 cmolc kg clay, the soil finally classifies as Lixic Vetic Ferralsol (Ferric, Rhodic).
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Chapter 2 Diagnostic horizons, properties and materials
Diagnostic horizons and properties are characterized by a combination of attributes that reflect widespread, common results of the processes of soil formation (Bridges, 1997) or indicate specific conditions of soil formation. Their features can be observed or measured, either in the field or in the laboratory, and require a minimum or maximum expression to qualify as diagnostic. In addition, diagnostic horizons require a certain thickness, thus forming a recognizable layer in the soil. Diagnostic materials are materials that influence pedogenetic processes significantly. DIAGNOSTIC HORIZONS Albic horizon General description The albic horizon (from Latin albus, white) is a light-coloured subsurface horizon from which clay and free iron oxides have been removed, or in which the oxides have been segregated to the extent that the colour of the horizon is determined by the colour of the sand and silt particles rather than by coatings on these particles. It generally has a weakly expressed soil structure or lacks structural development altogether. The upper and lower boundaries are normally abrupt or clear. The morphology of the boundaries is variable and sometimes associated with albeluvic tonguing. Albic horizons usually have coarser textures than the overlying or underlying horizons. However, with respect to an underlying spodic horizon, this difference may only be slight. Many albic horizons are associated with wetness and contain evidence of reducing conditions. Diagnostic criteria An albic horizon has: 1. a Munsell colour (dry) with either: a. a value of 7 or 8 and a chroma of 3 or less; or b. a value of 5 or 6 and a chroma of 2 or less; and 2. a Munsell colour (moist) with either: a. a value of 6, 7 or 8 and a chroma of 4 or less; or b. a value of 5 and a chroma of 3 or less; or c. a value of 4 and a chroma of 2 or less2. A chroma of 3 is permitted if the parent materials have a hue of 5 YR or redder, and the chroma is due to the colour of uncoated silt or sand grains; and 3. a thickness of 1 cm or more. Field identification Identification in the field depends on soil colours. In addition, a ×10 hand-lens may be used to ascertain that sand and silt grains are free of coatings.
2 Colour requirements have been changed slightly with respect to those defined by FAO–UNESCO–ISRIC (FAO, 1988) and Soil Survey Staff (1999) in order to accommodate albic horizons with a considerable shift in chroma when wetted. Such albic horizons occur frequently in, for example, southern Africa.
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Additional characteristics The presence of coatings around sand and silt grains can be determined using an optical microscope for analysing thin sections. Uncoated grains usually show a very thin rim at their surface. Coatings may be of an organic nature, consist of iron oxides, or both, and are dark coloured under translucent light. Iron coatings become reddish in colour under reflected light, while organic coatings remain brownish-black. Relationships with some other diagnostic horizons Albic horizons are normally overlain by humus-enriched surface layers but may be at the surface as a result of erosion or artificial removal of the surface layer. They can be considered an extreme type of eluvial horizon, and usually occur in association with illuvial horizons such as an argic, natric or spodic horizon, which they overlie. In sandy materials, albic horizons can reach considerable thickness, up to several metres, especially in humid tropical regions, and associated diagnostic horizons may be hard to establish. Anthraquic horizon General description An anthraquic horizon (from Greek anthropos, human, and Latin aqua, water) is a human- induced surface horizon that comprises a puddled layer and a plough pan. Diagnostic criteria An anthraquic horizon is a surface horizon and has: 1. a puddled layer with both: a. a Munsell hue of 7.5 YR or yellower, or GY, B or BG hues; value (moist) of 4 or less; chroma (moist) of 2 or less3; and b. sorted soil aggregates and vesicular pores; and 2. a plough pan underlying the puddled layer with all of the following: a. a platy structure; and b. a bulk density higher by 20 percent or more (relative) than that of the puddled layer; and c. yellowish-brown, brown or reddish-brown iron–manganese mottles or coatings; and 3. a thickness of 20 cm or more. Field identification An anthraquic horizon shows evidence of reduction and oxidation owing to flooding for part of the year. When not flooded, it is very dispersible and has a loose packing of sorted small aggregates. The plough pan is compact, with platy structure and very slow infiltration. It has yellowish-brown, brown or reddish-brown rust mottles along cracks and root holes. Anthric horizon General description An anthric horizon (from Greek anthropos, human) is a moderately thick, dark-coloured surface horizon that is the result of long-term cultivation (ploughing, liming, fertilization, etc.). Diagnostic criteria An anthric horizon4 is a mineral surface horizon and: 1. meets all colour, structure and organic matter requirements of a mollic or umbric horizon; and 2. shows evidence of human disturbance by having one or more of the following: a. an abrupt lower boundary at ploughing depth, a plough pan; or b. lumps of applied lime; or c. mixing of soil layers by cultivation; or
3 Colour requirements taken from the Chinese soil taxonomy (CRGCST, 2001). 4 Modified after Krogh and Greve (1999).
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-1 d. 1.5 g kg or more P2O5 soluble in 1-percent citric acid; and 3. has less than 5 percent (by volume) of animal pores, coprolites or other traces of soil animal activity below tillage depth; and 4. has a thickness of 20 cm or more. Field identification Anthric horizons are associated with old arable lands that have been cultivated for centuries. Signs of mixing or cultivation, evidence of liming (e.g. remnants of applied lime chunks) and their dark colour are the main criteria for recognition. Relationships with other horizons Anthric horizons can resemble or overlap with mollic or umbric horizons. Anthric horizons may have developed from umbric horizons through human intervention. As they have been limed for a considerable period of time, their base saturation is high. This sets them apart from umbric horizons. The usually low biological activity below tillage depth is uncommon in soils with mollic horizons. Argic horizon General description The argic horizon (from Latin argilla, white clay) is a subsurface horizon with distinct higher clay content than the overlying horizon. The textural differentiation may be caused by: • an illuvial accumulation of clay; • predominant pedogenetic formation of clay in the subsoil; • destruction of clay in the surface horizon; • selective surface erosion of clay; • upward movement of coarser particles due to swelling and shrinking; • biological activity; • a combination of two or more of these different processes. Sedimentation of surface materials that are coarser than the subsurface horizon may enhance a pedogenetic textural differentiation. However, a mere lithological discontinuity, such as may occur in alluvial deposits, does not qualify as an argic horizon. Soils with argic horizons often have a specific set of morphological, physico-chemical and mineralogical properties other than a mere clay increase. These properties allow various types of argic horizons to be distinguished and their pathways of development to be traced (Sombroek, 1986). Diagnostic criteria An argic horizon: 1. has a texture of loamy sand or finer and 8 percent or more clay in the fine earth fraction; and 2. one or both of the following: a. has, if an overlying coarser textured horizon is present that is not ploughed and not separated from the argic horizon by a lithological discontinuity, more total clay than this overlying horizon such that: i. if the overlying horizon has less than 15 percent clay in the fine earth fraction, the argic horizon must contain at least 3 percent more clay; or ii. if the overlying horizon has 15 percent or more but less than 40 percent clay in the fine earth fraction, the ratio of clay in the argic horizon to that of the overlying horizon must be 1.2 or more; or iii. if the overlying horizon has 40 percent or more total clay in the fine earth fraction, the argic horizon must contain at least 8 percent more clay; or b. has evidence of clay illuviation in one or more of the following forms: i. oriented clay bridging the sand grains; or
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ii. clay films lining pores; or iii. clay films on both vertical and horizontal surfaces of soil aggregates; or iv. in thin section, oriented clay bodies that constitute 1 percent or more of the section; or v. a coefficient of linear extensibility (COLE) of 0.04 or higher, and a ratio of fine clay5 to total clay in the argic horizon greater by 1.2 times or more than the ratio in the overlying coarser textured horizon; and 3. has, if an overlying coarser textured horizon is present that is not ploughed and not separated from the argic horizon by a lithological discontinuity, an increase in clay content within a vertical distance of one of the following: a. 30 cm, if there is evidence of clay illuviation; or b. 15 cm; and 4. does not form part of a natric horizon; and 5. has a thickness of one-tenth or more of the sum of the thicknesses of all overlying horizons, if present, and one of the following: a. 7.5 cm or more, if it is not entirely composed of lamellae (that are 0.5 cm or more thick) and the texture is finer than loamy sand; or b. 15 cm or more (combined thickness, if composed entirely of lamellae that are 0.5 cm or more thick). . Field identification Textural differentiation is the main feature for recognition of argic horizons. The illuvial nature may be established using an ×10 hand-lens if clay skins occur on ped surfaces, in fissures, in pores and in channels – illuvial argic horizon should show clay skins on at least 5 percent of both horizontal and vertical ped faces and in the pores. Clay skins are often difficult to detect in shrink–swell soils. The presence of clay skins in protected positions, e.g. in pores, meets the requirements for an illuvial argic horizon. Additional characteristics The illuvial character of an argic horizon can best be established using thin sections. Diagnostic illuvial argic horizons must show areas with oriented clays that constitute on average at least 1 percent of the entire cross-section. Other tests involved are particle-size distribution analysis, to determine the increase in clay content over a specified depth, and the fine clay/total clay analysis. In illuvial argic horizons, the fine clay to total clay ratio is larger than in the overlying horizons, caused by preferential eluviation of fine clay particles. If the soil shows a lithological discontinuity over or within the argic horizon, or if the surface horizon has been removed by erosion, or if only a plough layer overlies the argic horizon, the illuvial nature must be clearly established. Relationships with some other diagnostic horizons Argic horizons are normally associated with and situated below eluvial horizons, i.e. horizons from which clay and Fe have been removed. Although initially formed as a subsurface horizon, argic horizons may occur at the surface as a result of erosion or removal of the overlying horizons. Some clay-increase horizons may have the set of properties that characterize the ferralic horizon, i.e. a low CEC and effective CEC (ECEC), a low content of water-dispersible clay and a low content of weatherable minerals, all over a depth of 50 cm. In such cases, a ferralic horizon has preference over an argic horizon for classification purposes. However, an argic horizon prevails if it overlies a ferralic horizon and it has, in its upper part over a depth of 30 cm, 10 percent or more water-dispersible clay, unless the soil material has geric properties or more than 1.4 percent organic carbon.
5 Fine clay: < 0.2 µm equivalent diameter.
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Argic horizons lack the sodium saturation characteristics of the natric horizon. Argic horizons in cool and moist, freely drained soils of high plateaus and mountains in tropical and subtropical regions may occur in association with sombric horizons. Calcic horizon General description The calcic horizon (from Latin calx, lime) is a horizon in which secondary calcium carbonate (CaCO3) has accumulated in a diffuse form (calcium carbonate present only in the form of fine particles of less than 1 mm, dispersed in the matrix) or as discontinuous concentrations (pseudomycelia, cutans, soft and hard nodules, or veins). The accumulation may be in the parent material or in subsurface horizons, but it can also occur in surface horizons. If the accumulation of soft carbonates becomes such that all or most of the pedological and/or lithological structures disappear and continuous concentrations of calcium carbonate prevail, a hypercalcic qualifier is used. Diagnostic criteria A calcic horizon has: 1. a calcium carbonate equivalent in the fine earth fraction of 15 percent or more; and 2. 5 percent or more (by volume) secondary carbonates or a calcium carbonate equivalent of 5 percent or more higher (absolute, by mass) than that of an underlying layer; and 3. a thickness of 15 cm or more. Field identification Calcium carbonate can be identified in the field using a 10-percent 1 M hydrochloric acid (HCl) solution. The degree of effervescence (audible only, visible as individual bubbles, or foam-like) is an indication of the amount of lime present. This test is important if only diffuse distributions are present. When foam develops after adding 1 M HCl, it indicates a calcium carbonate equivalent near or more than 15 percent. Other indications for the presence of a calcic horizon are: • white, pinkish to reddish, or grey colours (if not overlapping horizons rich in organic carbon); • a low porosity (interaggregate porosity is usually less than that in the horizon immediately above and, possibly, also less than in the horizon directly underneath). Calcium carbonate content may decrease with depth, but this is difficult to establish in some places, particularly where the calcic horizon occurs in the deeper subsoil. Therefore, accumulation of secondary lime is sufficient to diagnose a calcic horizon. Additional characteristics Determination of the amount of calcium carbonate (by mass) and the changes within the soil profile of the calcium carbonate content are the main analytical criteria for establishing the presence of a calcic horizon. Determination of the pH (H2O) enables distinction between accumulations with a basic (calcic) character (pH 8.0–8.7) due to the dominance of CaCO3, and those with an ultrabasic (non-calcic) character (pH > 8.7) because of the presence of MgCO3 or Na2CO3. In addition, microscopical analysis of thin sections may reveal the presence of dissolution forms in horizons above or below a calcic horizon, evidence of silicate epigenesis (calcite pseudomorphs after quartz), or the presence of other calcium carbonate accumulation structures, while clay mineralogical analyses of calcic horizons often show clays characteristic of confined environments, such as smectite, palygorskite and sepiolite. Relationships with some other diagnostic horizons When calcic horizons become indurated, transition takes place to the petrocalcic horizon, the expression of which may be massive or platy.
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In dry regions and in the presence of sulphate-bearing soil or groundwater solutions, calcic horizons occur associated with gypsic horizons. Calcic and gypsic horizons typically (but not everywhere) occupy different positions in the soil profile because of the difference in solubility of calcium carbonate and gypsum, and they can normally be distinguished clearly from each other by the difference in morphology. Gypsum crystals tend to be needle-shaped, often visible to the naked eye, whereas pedogenetic calcium carbonate crystals are much finer in size. Cambic horizon General description The cambic horizon (from Italian cambiare, to change) is a subsurface horizon showing evidence of alteration relative to the underlying horizons. Diagnostic criteria A cambic horizon: 1. has a texture in the fine earth fraction of very fine sand, loamy very fine sand6, or finer; and 2. has soil structure or absence of rock structure7 in half or more of the volume of the fine earth; and 3. shows evidence of alteration in one or more of the following: a. higher Munsell chroma (moist), higher value (moist), redder hue, or higher clay content than the underlying or an overlying layer; or b. evidence of removal of carbonates8 or gypsum; or c. presence of soil structure and absence of rock structure in the entire fine earth, if carbonates and gypsum are absent in the parent material and in the dust that falls on the soil; and 4. does not form part of a plough layer, does not consist of organic material and does not form part of an anthraquic, argic, calcic, duric, ferralic, fragic, gypsic, hortic, hydragric, irragric, mollic, natric, nitic, petrocalcic, petroduric, petrogypsic, petroplinthic, pisoplinlithic, plaggic, plinthic, salic, sombric, spodic, umbric, terric, or vertic or voronic horizon; and 5. has a thickness of 15 cm or more. Relationships with some other diagnostic horizons The cambic horizon can be considered the predecessor of many other diagnostic horizons. All these horizons have specific properties, such as illuvial or residual accumulations, removal of substances other than carbonates or gypsum, accumulation of soluble components, or development of specific soil structure, that are not recognized in the cambic horizon. Cambic horizons in cool and moist, freely drained soils of high plateaus and mountains in tropical and subtropical regions may occur in association with sombric horizons. Cryic horizon General description The cryic horizon (from Greek kryos, cold, ice) is a perennially frozen soil horizon in mineral or organic materials. Diagnostic criteria A cryic horizon has:
6 Very fine sand and loamy very fine sand: 50 percent or more of the fraction between 63 and 125 µm. 7 The term rock structure also applies to unconsolidated sediments in which stratification s still visible. 8 A cambic horizon always has less carbonate than an underlying horizon with calcium carbonate accumulation. However, not all primary carbonates have to be leached from a horizon in order for it to qualify as a cambic horizon. If all coarse fragments in the underlying horizon are completely coated with lime, some of these fragments in the cambic horizon are partly free of coatings. If the coarse fragments in the horizon showing calcium carbonate accumulation are coated only on the underside, those in the cambic horizon are free of coatings.
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1. continuously for two or more consecutive years one of the following: a. massive ice, cementation by ice or readily visible ice crystals; or b. a soil temperature of 0 °C or less and insufficient water to form readily visible ice crystals; and 2. a thickness of 5 cm or more. Field identification Cryic horizons occur in areas with permafrost9 and show evidence of perennial ice segregation, often associated with evidence of cryogenic processes (mixed soil material, disrupted soil horizons, involutions, organic intrusions, frost heave, separation of coarse from fine soil materials, cracks, patterned surface features, such as earth hummocks, frost mounds, stone circles, stripes, nets and polygons) above the cryic horizon or at the soil surface. Soils that contain saline water do not freeze at 0 °C. In order to develop a cryic horizon, such soils must be cold enough to freeze. To identify features of cryoturbation, sorting or thermal contraction, a soil profile should intersect different elements of patterned ground, if any, or be wider than 2 m. Engineers distinguish between warm and cold permafrost. Warm permafrost has a temperature higher than -2 °C and has to be considered unstable. Cold permafrost has a temperature of -2 °C or lower and can be used more safely for construction purposes provided the temperature remains under control. Relationships with some other diagnostic horizons Cryic horizons may bear characteristics of histic, andic folic or spodic horizons, and may occur in association with salic, calcic, mollic or umbric horizons. In cold arid regions, yermic horizons may be found in association with cryic horizons. Duric horizon General description The duric horizon (from Latin durus, hard) is a subsurface horizon showing weakly cemented to indurated nodules or concretions cemented by silica (SiO2), presumably in the form of opal and microcrystalline forms of silica (durinodes). Durinodes often have carbonate coatings that have to be removed with HCl before slaking the durinodes with potassium hydroxide (KOH). Diagnostic criteria A duric horizon has: 1. 10 percent or more (by volume) of weakly cemented to indurated, silica-enriched nodules (durinodes) or fragments of a broken-up petroduric horizon that show all of the following: a. when air-dry, less than 50 percent slake in 1 M HCl even after prolonged soaking, but 50 percent or more slake in concentrated KOH, concentrated NaOH or in alternating acid and alkali; and b. are firm or very firm and brittle when wet, both before and after treatment with acid; and c. have a diameter of 1 cm or more; and 2. a thickness of 10 cm or more. Additional characteristics Dry durinodes do not slake appreciably in water, but prolonged soaking can result in the breaking-off of very thin platelets and in some slaking. In cross-section, most durinodes are roughly concentric, and concentric stringers of opal may be visible under a hand-lens.
9 Permafrost: layer of soil or rock, at some depth beneath the surface, in which the temperature has been continuously below 0 °C for at least some years. It exists where summer heating fails to reach the base of the layer of frozen ground. Arctic Climatology and Meteorology Glossary, National Snow and Ice Data Center, Boulder, USA (http://nsidc.org).
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Relationships with some other diagnostic horizons In arid regions, duric horizons occur associated with gypsic, petrogypsic, calcic and petrocalcic horizons. In more humid climates, the duric horizons may grade into fragic horizons. Ferralic horizon General description The ferralic horizon (from Latin ferrum, iron, and alumen, alum) is a subsurface horizon resulting from long and intense weathering in which the clay fraction is dominated by low- activity clays and the silt and sand fractions by highly resistant minerals, such as (hydr)oxides of Fe, Al, Mn and titanium (Ti). Diagnostic criteria A ferralic horizon: 1. has a sandy loam or finer particle size and less than 80 percent (by volume) gravel, stones, pisoplinthic nodules or petroplinthic gravel; and -1 10 2. has a CEC (by 1 M NH4OAc) of less than 16 cmolc kg clay and an ECEC (sum of -1 exchangeable bases plus exchangeable acidity in 1 M KCl) of less than 12 cmolc kg clay; and 3. has less than 10 percent water-dispersible clay, unless it has one or both of the following: a. geric properties; or b. 1.4 percent or more organic carbon; and 4. has less than 10 percent (by grain count) weatherable minerals11 in the 0.05–0.2 mm fraction; and 5. does not have andic or vitric properties; and 6. has a thickness of 30 cm or more. Field identification Ferralic horizons are associated with old and stable landforms. The macrostructure seems to be moderate to weak at first sight but typical ferralic horizons have a strong microaggregation. The consistence is usually friable; the disrupted, dry soil material flows like flour between the fingers. Lumps of ferralic horizons are usually relatively light in mass because of the low bulk density; many ferralic horizons give a hollow sound when tapped, indicating high porosity. Illuviation and stress features such as clay skins and pressure faces are generally lacking. Boundaries of a ferralic horizon are normally diffuse and little differentiation in colour or particle-size distribution within the horizon can be detected. Texture is sandy loam or finer in the fine earth fraction; gravel, stones, pisoplinthic nodules or petroplinthic gravel comprise less than 80 percent (by volume). Additional characteristics As an alternative to the weatherable minerals requirement, a total reserve of bases (TRB = exchangeable plus mineral calcium [Ca], magnesium [Mg], potassium [K] and sodium [Na]) of -1 less than 25 cmolc kg soil may be indicative. Relationships with some other diagnostic horizons Ferralic horizons may meet the clay increase requirements that characterize the argic horizon. If the upper 30 cm of the horizon showing a clay increase contains 10 percent or more water- dispersible clay, an argic horizon has preference over a ferralic horizon for classification purposes, unless the soil material has geric properties or more than 1.4 percent organic carbon.
10 See Annex 1. 11 Examples of minerals that are included in the meaning of weatherable minerals are all 2:1 phyllosilicates, chlorite, sepiolites, palygorskite, allophane, 1:1 trioctahedral phyllosilicates (serpentines), feldspars, feldspathoids, ferromagnesian minerals, glass, zeolites, dolomite and apatite. The intent of the term weatherable minerals is to include those minerals that are unstable in humid climates compared with other minerals, such as quartz and 1:1 lattice clays, but that are more resistant to weathering than calcite (Soil Survey Staff 2003).
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Acid ammonium oxalate (pH 3) extractable Fe, Al and silicon (Alox, Feox, Siox) in ferralic horizons are very low, which sets them apart from the nitic horizons and layers with andic or vitric properties. Nitic horizons have a significant amount of active iron oxides: more than 0.2 percent acid oxalate (pH 3) extractable Fe from the fine earth fraction which, in addition, is more than 5 percent of the citrate-dithionite extractable Fe. Vitric properties require an Alox + ½Feox content of at least 0.4 percent, and andic properties at least 2 percent. The interface with the cambic horizon is formed by the CEC/ECEC/weatherable mineral requirements. Some cambic horizons have a low CEC; however, the amount of weatherable minerals (or, alternatively, the TRB) is too high for a ferralic horizon. Such horizons represent an advanced stage of weathering and form the transition between the cambic and the ferralic horizon. Ferralic horizons in cool and moist, freely drained soils of high plateaus and mountains in tropical and subtropical regions may occur in association with sombric horizons. Ferric horizon General description The ferric horizon (from Latin ferrum, iron) is one in which segregation of Fe, or Fe and manganese (Mn), has taken place to such an extent that large mottles or discrete nodules have formed and the intermottle/internodular matrix is largely depleted of Fe. Generally, such segregation leads to poor aggregation of the soil particles in Fe-depleted zones and compaction of the horizon. Diagnostic criteria A ferric horizon has: 1. has one or both of the following: a. 15 percent or more of the exposed area occupied by coarse mottles with a Munsell hue redder than 7.5 YR and a chroma of more than 5, moist; or b. 5 percent or more of the volume consisting of discrete reddish to blackish nodules with a diameter of 2 mm or more, with at least the exteriors of the nodules being at least weakly cemented or indurated and the exteriors having redder hue or stronger chroma than the interiors; and 2. less than 40 percent of the volume consisting of strongly cemented or indurated nodules and an absence of continuous, fractured or broken sheets; and 2. less than 15 percent consisting of firm to weakly cemented nodules or mottles that change irreversibly to strongly cemented or indurated nodules or mottles on exposure to repeated wetting and drying with free access of oxygen does not form part of a petroplinthic, pisoplinthic or plinthic horizon; and 3. has a thickness of 15 cm or more. Relationships with some other diagnostic horizons If the amount of weakly-cemented nodules or mottles reaches 15 percent or more (by volume) and these harden irreversibly to hard nodules or a hardpan or to irregular aggregates on exposure to repeated wetting and drying with free access of oxygen, the horizon is considered to be a plinthic horizon. Therefore, ferric horizons may, in tropical or subtropical regions, grade laterally into plinthic horizons. If the amount of hard nodules reaches 40 percent or more, it is a pisoplinthic horizon. Folic horizon General description The folic horizon (from Latin folium, leaf) is a surface horizon, or a subsurface horizon occurring at shallow depth, that consists of well-aerated organic material. Diagnostic criteria A folic horizon consists of organic material that:
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1. is saturated with water for less than 30 consecutive days in most years; and 2. has a thickness of 10 cm or more. Relationships with some other diagnostic horizons Histic horizons have similar characteristics to the folic horizon; however, these are saturated with water for one month or more in most years. Moreover, the composition of the histic horizon is generally different from that of the folic horizon as the vegetative cover is often different. Fragic horizon General description The fragic horizon (from Latin frangere, to break) is a natural non-cemented subsurface horizon with pedality and a porosity pattern such that roots and percolating water penetrate the soil only along interped faces and streaks. The natural character excludes plough pans and surface traffic pans. Diagnostic criteria A fragic horizon: 1. shows evidence of alteration12, at least on the faces of structural units; separations between these units, which allow roots to enter, have an average horizontal spacing of 10 cm or more; and 2. contains less than 0.5 percent (by mass) organic carbon; and 3. shows in 50 percent or more of the volume slaking or fracturing of air-dry clods, 5– 10 cm in diameter, within 10 minutes when placed in water; and 4. does not cement upon repeated wetting and drying; and 5. has a penetration resistance at field capacity of 50 kPa 4Mpa or more in 90 percent or more of the volume; and 6. does not show effervescence after adding a 10-percent 1 M HCl solution; and 7. has a thickness of 15 cm or more. Field identification A fragic horizon has a prismatic and/or blocky structure. The inner parts of the prisms may have a relatively high total porosity (including pores larger than 200 mm) but, as a result of a dense outer rim, there is no continuity between the intraped pores and the interped pores and fissures. The result is a closed box system with 90 percent or more of the soil volume that cannot be explored by roots and is isolated from percolating water. It is essential that the required soil volume be measured from both vertical and horizontal sections; horizontal sections often reveal polygonal structures. Three or four such polygons (or a cut up to 1 m2) are sufficient to test the volumetric basis for the definition of the fragic horizon. The ped interface can have the colour, mineralogical and chemical characteristics of an eluvial or albic horizon, or meet the requirements of albeluvic tonguing. In the presence of a fluctuating water table, this part of the soil is depleted of Fe and Mn. A concomitant Fe accumulation is observed at the level of the ped surface and Mn accumulations will occur further inside the peds (stagnic colour pattern). Fragic horizons are commonly loamy, but loamy sand and clay textures are not excluded. In the latter case, the clay mineralogy is dominantly kaolinitic. Dry clods are hard to extremely hard; moist clods are firm to extremely firm; moist consistence may be brittle. A ped or clod from a fragic horizon tends to rupture suddenly under pressure rather than to undergo slow deformation. The fragic horizon has little active faunal activity except, occasionally, between the polygons.
12 As defined in the cambic horizon.
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Relationships with some other diagnostic horizons A fragic horizon may underlie, although not necessarily directly, an albic, cambic, spodic or argic horizon, unless the soil has been truncated. It can overlap partly or completely with an argic horizon. Laterally, fragic horizons may grade into (petro-) duric horizons in dry regions. Moreover, fragic horizons can have reducing conditions and a stagnic colour pattern. Fulvic horizon General description The fulvic horizon (from Latin fulvus, dark yellow) is a thick, dark-brown coloured horizon at or near to the surface that is typically associated with short-range-order minerals (commonly allophane) or with organo-aluminium complexes. It has a low bulk density and contains highly humified organic matter that shows a lower ratio of humic acids to fulvic acids compared with the melanic horizon. Diagnostic criteria A fulvic horizon has: 1. andic properties; and 2. one or both of the following: a. a Munsell colour value or chroma (moist) of more than 2; or b. a melanic index13 of 1.70 or more; and 3. a weighted average of 6 percent or more organic carbon, and 4 percent or more organic carbon in all parts; and 4. a cumulative thickness of 30 cm or more with less than 10 cm non-fulvic material in between. Field identification When dark brown, the fulvic horizon is easily identifiable by its colour, thickness, as well as its typical, although not exclusive14, association with pyroclastic deposits. Distinction between the blackish coloured fulvic and melanic horizons is made after determining the melanic index, which requires laboratory analyses. Gypsic horizon General description The gypsic horizon (from Greek gypsos) is a commonly non-cemented horizon containing secondary accumulations of gypsum (CaSO4.2H2O) in various forms. If the accumulation of gypsum becomes such that all or most of the pedological and/or lithological structures disappear and continuous concentrations of gypsum prevail, a hypergypsic qualifier is used. Diagnostic criteria A gypsic horizon has: 1. 5 percent15 or more gypsum and 1 percent or more (by volume) of visible secondary gypsum; and 2. a product of thickness (in centimetres) times gypsum content (percentage) of 150 or more; and 3. a thickness of 15 cm or more. Field identification Gypsum occurs as pseudomycelia, as coarse crystals, as nests, beards or coatings, as elongated groupings of fibrous crystals, or as powdery accumulations. The last form gives the gypsic
13 See Annex 1. 14 Fulvic horizons may also be found in aluandic-type of soils derived from other material than pyroclastics. 15 -1 The percentage gypsum is can also be calculated as the product of gypsum content, expressed as cmolc kg soil, and the equivalent mass of gypsum (86) expressed as a percentage.
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horizon a massive structure. The distinction between compact powdery accumulations and the others is important in terms of soil capability. Gypsum crystals may be mistaken for quartz. Gypsum is soft and can easily be broken between thumbnail and forefinger. Quartz is hard and cannot be broken except by hammering. Gypsic horizons may be associated with calcic horizons but usually occur in separate positions within the soil profile, because of the higher solubility of gypsum compared with lime. Additional characteristics Determination of the amount of gypsum in the soil to verify the required content and increase, as well as thin section analysis, is helpful to establish the presence of a gypsic horizon and the distribution of the gypsum in the soil mass. Relationships with some other diagnostic horizons When gypsic horizons become indurated, transition takes place to the petrogypsic horizon, the expression of which may be as massive or platy structures. In dry regions, gypsic horizons are associated with calcic or salic horizons. Calcic and gypsic horizons usually occupy distinct positions in the soil profile as the solubility of calcium carbonate is different from that of gypsum. They normally can be distinguished clearly from each other by the morphology (see calcic horizon). Salic and gypsic horizons also occupy different positions for the same reasons. Histic horizon General description The histic horizon (from Greek histos, tissue) is a surface horizon, or a subsurface horizon occurring at shallow depth, that consists of poorly aerated organic material. Diagnostic criteria A histic horizon consists of organic material that: 1. is saturated with water for 30 consecutive days or more in most years (unless drained); and 2. has a thickness of 10 cm or more. If the layer with organic material is less than 20 cm thick, the upper 20 cm of the soil after mixing, or if continuous rock is present within 20 cm depth, the entire soil above after mixing, must contain 20 percent or more organic carbon. Relationships with some other diagnostic horizons The folic horizon has similar characteristics to the histic horizon; however, the folic horizon is saturated with water for less than one month in most years. Moreover, the composition of the histic horizon is generally different from that of the folic horizon as the vegetative cover is often different. The lower limit of organic carbon content, varying from 12 percent (20 percent organic matter) to 18 percent organic carbon (30 percent organic matter), sets the histic horizon apart from mollic or umbric horizons, which have these contents as upper limits. Histic horizons with less than 25 percent organic carbon may have andic or vitric properties. Hortic horizon General description A hortic horizon (from Latin hortus, garden) is a human-induced mineral surface horizon that results from deep cultivation, intensive fertilization and/or long-continued application of human and animal wastes and other organic residues (e.g. manures, kitchen refuse, compost and night soil). Diagnostic criteria A hortic horizon is a mineral surface horizon and has: 1. a Munsell colour value and chroma (moist) of 3 or less; and
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2. a weighted average organic carbon content of 1 percent or more; and 16 -1 3. a 0.5 M NaHCO3 extractable P2O 5 content of 100 mg kg fine earth or more in the upper 25 cm 17; and 4. a base saturation (by 1 M NH4OAc) of 50 percent or more; and 5. 25 percent (by volume) or more of animal pores, coprolites or other traces of soil animal activity; and 6. a thickness of 20 cm or more. Field identification The hortic horizon is thoroughly mixed. Potsherds and other artefacts are common although often abraded. Tillage marks or evidence of mixing of the soil can be present. Relationships with some other diagnostic horizons Hortic horizons closely resemble mollic horizons. Therefore, the human influence must be clearly established in order to separate the two diagnostic horizons. Hydragric horizon General description A hydragric horizon (from Greek hydor, water, and Latin ager, field) is a human-induced subsurface horizon associated with wet cultivation. Diagnostic criteria A hydragric horizon is associated with wet cultivation and has: 1. one or more of the following: a. Fe or Mn coatings or Fe or Mn concretions; or b. dithionite-citrate extractable Fe 2 times or more, or dithionite-citrate extractable Mn 4 times or more that of the surface horizon; or c. redox depleted zones with a Munsell colour value 4 or more and a chroma of 2 or less (both moist) in macropores; and 2. a thickness of 10 cm or more. Field identification The hydragric horizon occurs below the puddled layer and the plough pan of an anthraquic horizon. It has either reduction features in pores, such as coatings or halos with a colour hue of 2.5 Y or yellower and a chroma (moist) of 2 or less, or segregations of Fe and/or Mn in the matrix as a result of the oxidative environment. It usually shows grey clay-fine silt and clay-silt- humus cutans on ped faces. Irragric horizon General description The irragric horizon (from Latin irrigare, to irrigate, and ager, field) is a human-induced mineral surface horizon that builds up gradually through continuous application of irrigation water with substantial amounts of sediments, and which may include fertilizers, soluble salts, organic matter, etc. Diagnostic criteria An irragric horizon is a mineral surface horizon and has: 1. a uniformly structured surface layer; and 2. a higher clay content, particularly fine clay, than the underlying original soil; and 3. relative differences among medium, fine and very fine sand, clay and carbonates less than 20 percent among parts within the horizon; and
16 Known as the Olsen routine method (Olsen et al., 1954). 17 Gong et al., 1997.
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4. a weighted average organic carbon content of 0.5 percent or more, decreasing with depth but remaining at 0.3 percent or more at the lower limit of the irragric horizon; and 5. 25 percent (by volume) or more of animal pores, coprolites or other traces of soil animal activity; and 6. a thickness of 20 cm or more. Field identification Soils with an irragric horizon show evidence of surface raising, which may be inferred either from field observation or from historical records. The irragric horizon shows evidence of considerable biological activity. The lower boundary is clear and irrigation deposits or buried soils may be present below. Relationships with some other diagnostic horizons Irragric horizons differ from fluvic materials in lacking evidence of stratification owing to continuous ploughing. Melanic horizon General description The melanic horizon (from Greek melas, black) is a thick, black horizon at or near the surface, which is typically associated with short-range-order minerals (commonly allophane) or with organo-aluminium complexes. It has a low bulk density and contains highly humified organic matter that shows a lower ratio of fulvic acids to humic acids compared with the fulvic horizon. Diagnostic criteria A melanic horizon has: 1. andic properties; and 2. a Munsell colour value and chroma (both moist) of 2 or less,; and 3. a melanic index18 of less than 1.70; and 4. a weighted average of 6 percent or more organic carbon, and 4 percent or more organic carbon in all parts; and 5. a cumulative thickness of 30 cm or more with less than 10 cm non-melanic material in between. Field identification The intense dark black colour, its thickness, as well as its common association with pyroclastic deposits help to recognize the melanic horizon in the field. However, laboratory analyses to determine the type of organic matter may be are necessary to identify the melanic horizon unambiguously. Mollic horizon General description The mollic horizon (from Latin mollis, soft) is a thick, well-structured, dark-coloured surface horizon with a high base saturation and a moderate to high content of organic matter. Diagnostic criteria A mollic horizon, after mixing either the upper 20 cm of the mineral soil or, if continuous rock, a cryic, petrocalcic, petroduric, petrogypsic or petroplinthic horizon is present within 20 cm of the mineral soil surface, the entire mineral soil above, has: 1. a soil structure sufficiently strong that the horizon is not both massive and hard or very hard when dry in both the mixed part and the underlying unmixed part if the minimum thickness is larger than 20 cm (prisms larger than 30 cm in diameter are included in the meaning of massive if there is no secondary structure within the prisms); and
18 See Annex 1.
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2. Munsell colours with a chroma of 3 or less when moist, a value of 3 or less when moist and 5 or less when dry on broken samples in both the mixed part and the underlying unmixed part if the minimum thickness is greater than 20 cm. If there is 40 percent or more finely divided lime, the limits of dry colour value are waived; the colour value, moist, is 5 or less. The colour value is one unit or more darker than that of the parent material (both moist and dry), unless the parent material has a colour value of 4 or less, moist, in which case the colour contrast requirement is waived. If a parent material is not present, comparison must be made with the layer immediately underlying the surface layer; and 3. an organic carbon content of 0.6 percent or more in both the mixed part and the underlying unmixed part if the minimum thickness is larger than 20 cm. The organic carbon content is 2.5 percent or more if the colour requirements are waived because of finely divided lime, or 0.6 percent more than in the parent material if the colour requirements are waived because of dark coloured parent materials; and 4. a base saturation (by 1 M NH4OAc) of 50 percent or more on a weighted average throughout the depth of the horizon; and 5. a thickness of one of the following: a. 10 cm or more if directly overlying continuous rock, or a cryic, petrocalcic, petroduric, petrogypsic or petroplinthic horizon; or b. 20 cm or more and one-third or more of the thickness between the mineral soil surface and the upper boundary of continuous rock, or a calcic, cryic, gypsic, petrocalcic, petroduric, petrogypsic, petroplinthic or salic horizon or calcaric, fluvic or gypsyric gypsiric material within 75 cm; or c. 20 cm or more and one-third or more of the thickness between the mineral soil surface and the lower boundary of the lowest diagnostic horizon within 75 cm and, if present, above any of the diagnostic horizons or materials listed under b.; or d. 25 cm or more. Field identification A mollic horizon may easily be identified by its dark colour, caused by the accumulation of organic matter, well-developed structure (usually a granular or fine subangular blocky structure), an indication of high base saturation (e.g. pHwater > 6), and its thickness. Relationships with some other diagnostic horizons The base saturation of 50 percent separates the mollic horizon from the umbric horizon, which is otherwise similar. The upper limit of organic carbon content varies from 12 percent (20 percent organic matter) to 18 percent organic carbon (30 percent organic matter), which is the lower limit for the histic horizon, or 20 percent, the lower limit for a folic horizon. A special type of mollic horizon is the voronic horizon. It has a higher organic carbon content (1.5 percent or more), a specific structure (granular or fine subangular blocky), a very dark colour in its upper part, a high biological activity, and a minimum thickness of 35 cm. Natric horizon General description The natric horizon (from Arabic natroon, salt) is a dense subsurface horizon with distinct higher clay content than the overlying horizon or horizons. It has a high content in exchangeable Na and/or Mg. Diagnostic criteria A natric horizon: 1. has a texture of loamy sand or finer and 8 percent or more clay in the fine earth fraction; and 2. one or both of the following:
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a. has, if an overlying coarser textured horizon is present that is not ploughed and not separated from the natric horizon by a lithological discontinuity, more clay than this overlying horizon such that: i. if the overlying horizon has less than 15 percent clay in the fine earth fraction, the natric horizon must contain at least 3 percent more clay; or ii. if the overlying horizon has 15 percent or more and less than 40 percent clay in the fine earth fraction, the ratio of clay in the natric horizon to that of the overlying horizon must be 1.2 or more; or iii. if the overlying horizon has 40 percent or more clay in the fine earth fraction, the natric horizon must contain at least 8 percent more clay; or b. has evidence of clay illuviation in one or more of the following forms: i. oriented clay bridging the sand grains; or ii. clay films lining pores; or iii. clay films on both vertical and horizontal surfaces of soil aggregates; or iv. in thin sections, oriented clay bodies that constitute 1 percent or more of the section; or v. a COLE of 0.04 or higher, and a ratio of fine clay19 to total clay in the natric horizon greater by 1.2 times or more than the ratio in the overlying coarser textured horizon; and 3. has, if an overlying coarser textured horizon is present that is not ploughed and not separated from the natric horizon by a lithological discontinuity, an increase in clay content within a vertical distance of 30 cm; and 4. has one or more of the following: a. a columnar or prismatic structure in some part of the horizon; or b. a blocky structure with tongues of an overlying coarser textured horizon in which there are uncoated silt or sand grains, extending 2.5 cm or more into the natric horizon; or c. a massive appearance; and 5. has an exchangeable Na percentage (ESP20) of 15 or more within the upper 40 cm, or more exchangeable Mg plus Na than Ca plus exchange acidity (at pH 8.2) within the same depth if the saturation with exchangeable Na is 15 percent or more in some subhorizon within 200 cm of the soil surface; and 6. has a thickness of one-tenth or more of the sum of the thicknesses of all overlying mineral horizons, if present, and one of the following: a. 7.5 cm or more, if it is not entirely composed of lamellae (that are 0.5 cm or more thick) and the texture is finer than loamy sand; or b. 15 cm or more (combined thickness, if composed entirely of lamellae that are 0.5 cm or more thick). Field identification The colour of the natric horizon ranges from brown to black, especially in the upper part. The structure is coarse columnar or prismatic, sometimes blocky or massive. Rounded and often whitish tops of the structural elements are characteristic. Both colour and structural characteristics depend on the composition of the exchangeable cations and the soluble salt content in the underlying layers. Often, thick and dark-coloured clay coatings occur, especially in the upper part of the horizon. Natric horizons have a poor aggregate stability and very low permeability under wet conditions. When dry, the natric horizon becomes hard to extremely hard. Soil reaction is strongly alkaline; pH (H2O) is more than 8.5.
19 Fine clay: < 0.2 µm equivalent diameter. 20 ESP = exchangeable Na × 100/CEC (at pH 7).
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Additional characteristics Natric horizons are characterized by a high pH (H2O), which is frequently more than 9.0. Another measure to characterize the natric horizon is the sodium adsorption ratio (SAR), which has to be 13 or more. The SAR is calculated from soil solution data (Na+, Ca2+, Mg2+ given in + 2+ 2+ 0.5 mmolc/litre): SAR = Na /[(Ca + Mg )/2] . Micromorphologically, natric horizons show a specific fabric. The peptized plasma shows a strong orientation in a mosaic or parallel-striated pattern. The plasma separations also show a high content in associated humus. Microcrusts, cutans, papules and infillings appear when the natric horizon is impermeable. Relationships with some other diagnostic horizons A surface horizon usually rich in organic matter overlies the natric horizon. This horizon of humus accumulation varies in thickness from a few centimetres to more than 25 cm, and may be a mollic horizon. An albic horizon may be present between the surface and the natric horizon. Frequently, a salt-affected layer occurs below the natric horizon. The salt influence may extend into the natric horizon, which besides being sodic then also becomes saline. Salts present may be chlorides, sulphates or carbonates/bicarbonates. The humus-illuvial part of natric horizons has a base saturation (by 1 M NH4OAc) of more than 50 percent or more, which separates it from the sombric horizon. Nitic horizon General description The nitic horizon (from Latin nitidus, shiny) is a clay-rich subsurface horizon. It has moderately to strongly developed polyhedric structure breaking to flat-edged or nutty structure elements with many shiny ped faces, which cannot or can only partially be attributed to clay illuviation. Diagnostic criteria A nitic horizon has: 1. less than 20 percent change (relative) in clay content over 12 cm to layers immediately above and below; and 2. all of the following: a. 30 percent or more clay; and b. a water-dispersible clay to total clay ratio less than 0.10; and c. a silt to clay ratio less than 0.40; and 3. moderate to strong, angular blocky structure breaking to flat-edged or nut-shaped elements with shiny ped faces. The shiny faces are not, or are only partially, associated with clay coatings; and 4. all of the following: a. 4.0 percent or more citrate-dithionite extractable Fe (free iron) in the fine earth fraction; and b. 0.20 percent or more acid oxalate (pH 3) extractable Fe (active iron) in the fine earth fraction; and c. a ratio between active and free iron of 0.05 or more; and 5. a thickness of 30 cm or more. Field identification A nitic horizon has a clay loam or finer texture but feels loamy. The change in clay content with the overlying and underlying horizons is gradual. Similarly, there is no abrupt colour change with the horizons above and below. The colours are of low value and chroma with hues often 2.5 YR, but sometimes redder or yellower. The structure is moderate to strong angular blocky, breaking to flat-edged or nut-shaped elements showing shiny faces.
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Additional characteristics -1 In many nitic horizons, the CEC (by 1 M NH4OAc) is less than 36 cmolc kg clay, or even less -1 21 than 24 cmolc kg clay . The ECEC (sum of exchangeable bases plus exchangeable acidity in 1 M KCl) is about half of the CEC. The moderate to low CEC and ECEC reflect the dominance of 1:1 lattice clays (either kaolinite and/or [meta]halloysite). Relationships with some other diagnostic horizons The nitic horizon may be considered as a special type of argic horizon, or a strongly expressed cambic horizon, with specific properties such as a low amount of water-dispersible clay and a high amount of active iron. As such, the nitic horizon has preference over both for classification purposes. Its mineralogy (kaolinitic/[meta]halloysitic) sets it apart from most vertic horizons, which have dominantly a smectitic mineralogy. However, nitic horizons may grade laterally into vertic horizons in lower landscape positions. The well-expressed soil structure, the high amount of active iron, and the frequently intermediate CEC in nitic horizons set them apart from ferralic horizons. Nitic horizons in cool and moist, freely drained soils of high plateaus and mountains in tropical and subtropical regions may occur in association with sombric horizons. Petrocalcic horizon General description A petrocalcic horizon (from Greek petros, rock, and Latin calx, lime) is an indurated calcic horizon that is cemented by calcium carbonate and, in places, by calcium and some magnesium carbonate. It is either massive or platy in nature, and extremely hard. Diagnostic criteria A petrocalcic horizon has: 1. very strong effervescence after adding a 10-percent 1 M HCl solution; and 2. induration or cementation, at least partially by secondary carbonates, to the extent that air-dry fragments do not slake in water and roots cannot enter except along vertical fractures (which have an average horizontal spacing of 10 cm or more and which occupy less than 20 percent [by volume] of the layer); and 3. extremely hard consistence when dry, so that it cannot be penetrated by spade or auger; and 4. a thickness of 10 cm or more, or 1 cm or more if it is laminar and rests directly on continuous rock. Field identification Petrocalcic horizons occur as non-platy calcrete (either massive or nodular) or as platy calcrete, of which the following types are the most common: • Lamellar calcrete: superimposed, separate, petrified layers varying in thickness from a few millimetres to several centimetres. The colour is generally white or pink. • Petrified lamellar calcrete: one or several extremely hard layers, grey or pink in colour. They are generally more cemented than the lamellar calcrete and very massive (no fine lamellar structures, but coarse lamellar structures may be present). Non-capillary pores in petrocalcic horizons are filled, and the hydraulic conductivity is moderately slow to very slow. Relationships with some other diagnostic horizons In arid regions, petrocalcic horizons may occur in association with (petro-) duric horizons, into which they may grade laterally. The cementing agent differentiates petrocalcic and duric horizons. In petrocalcic horizons, calcium and some magnesium carbonate constitute the main
21 See Annex 1.
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cementing agent while some accessory silica may be present. In duric horizons, silica is the main cementing agent, with or without calcium carbonate. Petrocalcic horizons also occur in association with gypsic or petrogypsic horizons. Petroduric horizon General description A petroduric horizon (from Greek petros, rock, and Latin durus, hard), also known as duripan or dorbank (South Africa), is a subsurface horizon, usually reddish or reddish brown in colour, that is cemented mainly by secondary silica (SiO2, presumably opal and microcrystalline forms of silica). Air-dry fragments of petroduric horizons do not slake in water, even after prolonged wetting. Calcium carbonate may be present as accessory cementing agent. Diagnostic criteria A petroduric horizon has: 1. induration or cementation in 50 percent or more (by volume) of some subhorizon; and 2. evidence of silica accumulation (opal or other forms of silica), e.g. as coatings in some pores, on some structural faces or as bridges between sand grains; and 3. when air-dry, less than 50 percent (by volume) that slakes in 1 M HCl even after prolonged soaking, but 50 percent or more that slakes in concentrated KOH, concentrated NaOH or in alternating acid and alkali; and 4. a lateral continuity such that roots cannot penetrate except along vertical fractures (which have an average horizontal spacing of 10 cm or more and which occupy less than 20 percent [by volume] of the layer); and 5. a thickness of 1 cm or more. Field identification A petroduric horizon has a very to extremely firm consistence when moist, and is very or extremely hard when dry. Effervescence after applying 1 M HCl may take place, but is probably not as vigorous as in petrocalcic horizons, which appear similar. However, it may occur in conjunction with a petrocalcic horizon. Relationships with some other diagnostic horizons In dry and arid climates, petroduric horizons may occur in association with petrocalcic horizons, into which they may grade laterally into petrocalcic horizons, and/or occur in conjunction with calcic or gypsic horizons, which they normally overlie. In more humid climates, petroduric horizons may grade laterally into fragic horizons. Petrogypsic horizon General description A petrogypsic horizon (from Greek petros, rock, and gypsos) is a cemented horizon containing secondary accumulations of gypsum (CaSO4.2H2O). Diagnostic criteria A petrogypsic horizon has: 1. 5 percent22 or more gypsum and 1 percent or more (by volume) visible secondary gypsum; and 2. induration or cementation, at least partially by secondary gypsum, at least partially, to the extent that air-dry fragments do not slake in water and that it cannot be penetrated by roots cannot enter except along vertical fractures (which have an average horizontal spacing of 10 cm or more and which occupy less than 20 percent [by volume] of the layer); and 3. a thickness of 10 cm or more.
22 -1 The percentage gypsum is can also be calculated as the product of gypsum content, expressed as cmolc kg soil, and the equivalent mass of gypsum (86) expressed as a percentage.
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Field identification Petrogypsic horizons are hard, whitish and composed predominantly of gypsum. They Old petrogypsic horizons may be capped by a thin, laminar layer of newly precipitated gypsum about 1 cm thick. Additional characteristics Determinations of the amount of gypsum in the soil to verify the required content and increase, as well as t Thin section analysis, are is a helpful techniques to establish the presence of a petrogypsic horizon and the distribution of the gypsum in the soil mass. In thin sections, the petrogypsic horizon shows a compacted microstructure with only a few cavities. The matrix is composed of densely packed lenticular gypsum crystals mixed with small amounts of detrital material. The matrix has a faint yellow colour in plain light. Irregular nodules formed by colourless transparent zones consist of coherent crystal aggregates with a hypidiotopic or xenotopic fabric and are mostly associated with pores or former pores. Traces of biological activity (pedotubules) are sometimes visible. Relationships with some other diagnostic horizons As the petrogypsic horizon develops from a gypsic horizon, the two are closely linked. Petrogypsic horizons frequently occur associated with calcic horizons. Calcic and gypsic accumulations usually occupy different positions in the soil profile because the solubility of calcium carbonate is different from that of gypsum. Normally, they can be distinguished clearly from each other by their morphology (see calcic horizon). Petroplinthic horizon General description A petroplinthic horizon (from Greek petros, rock, and plinthos, brick) is a continuous, fractured or broken layer of indurated material, in which Fe (and in cases also Mn) is an important cement and in which organic matter is either absent or present only in traces. Diagnostic criteria A petroplinthic horizon: 1. is a continuous, fractured or broken sheet of connected, strongly cemented to indurated a. reddish to blackish nodules; or b. reddish, yellowish to blackish mottles in platy, polygonal or reticulate patterns; and 2. has a penetration resistance23 of 4.5 MPa or more in 50 percent or more of the volume; and 3. has a ratio between acid oxalate (pH 3) extractable Fe and citrate-dithionite extractable Fe of less than 0.1024; and 4. has a thickness of 10 cm or more. Field identification Petroplinthic horizons are extremely hard; typically rusty brown to yellowish brown; either massive, or show an interconnected nodular, or a reticulate, platy or columnar pattern that encloses non-indurated material. They may be fractured or broken. Relationships with some other diagnostic horizons Petroplinthic horizons are closely associated with plinthic horizons from which they develop. In some places, plinthic horizons can be traced by following petroplinthic layers, which have formed, for example, in road cuts. The low ratio between acid oxalate (pH 3) extractable Fe and citrate-dithionite extractable Fe separates the petroplinthic horizon from thin iron pans, bog iron and indurated spodic horizons as occurring in, for example, Podzols, which in addition contain a fair amount of organic matter.
23 Asiamah (2000). From this point onwards, the horizon will start hardening irreversibly. 24 Estimated from data given by Varghese and Byju (1993).
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Pisoplinthic horizon General description A pisoplinthic horizon (from Latin pisum, pea, and Greek plinthos, brick) contains nodules that are strongly cemented to indurated with Fe (and in some cases also with Mn). Diagnostic criteria A pisoplinthic horizon has: 1. 40 percent or more of the volume occupied by discrete, strongly cemented to indurated, reddish to blackish nodules with a diameter of 2 mm or more; and 2. a thickness of 15 cm or more. Relationships with some other diagnostic horizons A pisoplinthic horizon results if a plinthic horizon hardens in the form of discrete nodules. The hardness and the amount of the nodules separate it also from the ferric horizon. Plaggic horizon General description A plaggic horizon (from Dutch plag, sod) is a black or brown human-induced mineral surface horizon that has been produced by long-continued manuring. In medieval times, sod and other materials were commonly used for bedding livestock and the manure was spread on fields being cultivated. The mineral materials brought in by this kind of manuring eventually produced an appreciably thickened horizon (in places as much as 100 cm or more thick) that is rich in organic carbon. Base saturation is typically low. Diagnostic criteria A plaggic horizon is a mineral surface horizon and: 1. has a texture of sand, loamy sand, sandy loam or loam, or a combination of them; and 2. contains artefacts, but less than 20 percent, or has spade marks below 30 cm depth or other evidence of agricultural activity below 30 cm depth; and 3. has Munsell colours with a value of 4 or less, moist, 5 or less, dry, and a chroma of 2 or less, moist; and 4. has an organic carbon content of 0.6 percent or more; and 5. occurs in locally raised land surfaces; and 6. has a thickness of 20 cm or more. Field identification The plaggic horizon has brownish or blackish colours, related to the origin of source materials. Its reaction is slightly to strongly acid. It shows evidence of agricultural operations such as spade marks as well as old cultivation layers. Plaggic horizons commonly overlie buried soils although the original surface layers may be mixed. The lower boundary is typically clear. Additional characteristics The texture is in most cases sand or loamy sand. Sandy loam and silt loam are rare. The P2O5 content (extractable in 1-percent citric acid) in plaggic horizons may be high, often more than 0.25 percent within 20 cm of the surface, but frequently more than 1 percent. Owing to the abandonment of the practice, phosphate contents may have lowered considerably, and can no longer be seen as diagnostic for the plaggic horizon. Buried soils may be observed at the base of the horizon although mixing can obscure the contact. Relationships with some other diagnostic horizons Few soil characteristics differentiate the terric and plaggic horizons from each other. Terric horizons usually show a high biological activity, have a neutral to slightly alkaline soil reaction (pH [H2O] is normally more than 7.0), and may contain free lime. The colour is strongly related to the source material or the underlying substrate. Buried soils may be observed at the base of the horizon although mixing can obscure the contact.
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The plaggic horizon has many characteristics in common with umbric horizons, and evidence of human influences, such as the spade marks or surface raising, is often required to distinguish between the two. Plinthic horizon General description A plinthic horizon (from Greek plinthos, brick) is a subsurface horizon that consists of an Fe- rich (in some cases also Mn-rich), humus-poor mixture of kaolinitic clay (and other products of strong weathering, such as gibbsite) with quartz and other constituents, and which changes irreversibly to a layer with hard nodules, a hardpan or irregular aggregates fragments on exposure to repeated wetting and drying with free access of oxygen. Diagnostic criteria A plinthic horizon has: 1. has within 15 percent or more of the volume, single or in combination: a. discrete nodules that are firm to weakly cemented, with a redder hue or stronger chroma than the surrounding material, and which change irreversibly to strongly cemented or indurated nodules on exposure to repeated wetting and drying with free access of oxygen; or b. mottles in platy, polygonal or reticulate patterns that are firm to weakly cemented, with a redder hue or stronger chroma than the surrounding material, and which change irreversibly to strongly cemented or indurated mottles on exposure to repeated wetting and drying with free access of oxygen; and 2. less than 40 percent of the volume strongly cemented or indurated nodules and no continuous, fractured or broken sheets does not form part of a petroplinthic or pisoplinthic horizon; and 3. has both: a. 2.5 percent (by mass) or more citrate-dithionite extractable Fe in the fine earth fraction or 10 percent or more in the nodules or mottles; and b. a ratio between acid oxalate (pH 3) extractable Fe and citrate-dithionite extractable Fe of less than 0.1025; and 4. has a thickness of 15 cm or more. Field identification A plinthic horizon shows red prominent nodules or mottles in platy, polygonal, vesicular or reticulate patterns. In a perennially moist soil, many nodules or mottles are not hard but firm or very firm and can be cut with a spade. They do not harden irreversibly as a result of a single cycle of drying and rewetting but repeated wetting and drying will change them irreversibly to hard nodules or a hardpan (ironstone) or irregular aggregates, especially if also exposed to heat from the sun. Additional characteristics Micromorphological studies may reveal the extent of impregnation of the soil mass by Fe. The plinthic horizon with nodules has developed under redoximorphic conditions caused by temporally stagnating water and shows a stagnic colour pattern. The plinthic horizon with mottles in platy, polygonal or reticulate patterns has developed under oximorphic conditions in the capillary fringe of groundwater. In this case, the plinthic horizon shows a gleyic colour pattern with oximorphic colours and is in many cases underlain by a whitish horizon. In many plinthic horizons, there are no prolonged reducing conditions.
25 Estimated from data given by Varghese and Byju (1993).
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Relationships with some other diagnostic horizons If the plinthic horizon hardens to a continuous sheet (which later may be broken or fractured), it becomes a petroplinthic horizon. If nodules reach 40 percent or more of the volume and harden separately, it becomes a pisoplinthic horizon. If the nodules or mottles that harden on exposure to repeated wetting and drying do not reach 15 percent of the volume, it may be a ferric horizon if it has 5 percent or more nodules or 15 percent or more mottles fulfilling certain additional requirements. Salic horizon General description The salic horizon (from Latin sal, salt) is a surface or shallow subsurface horizon that contains a secondary enrichment of readily soluble salts, i.e. salts more soluble than gypsum (CaSO4.2H2O; log Ks = -4.85 at 25 °C). Diagnostic criteria A salic horizon has: 1. averaged over its depth at some time of the year an electrical conductivity of the -1 saturation extract (ECe) of 15 dS m or more at 25 °C at some time of the year, or an ECe -1 of 8 dS m or more at 25 °C if the pH (H2O) of the saturation extract is 8.5 or more; and 2. averaged over its depth at some time of the year a product of thickness (in centimetres) -1 and ECe (in dS m ) of 450 or more; and 3. a thickness of 15 cm or more. Field identification Salicornica, Tamarix or other halophyte plants vegetation such as Tamarix and salt-tolerant crops are first indicators. Salt-affected layers are often puffy. Salts precipitate only after evaporation of the most soil moisture; if the soil is moist, salt may not be visible. Salts may precipitate at the surface (external Solonchaks) or at depth (internal Solonchaks). A salt crust is part of the salic horizon. Additional characteristics -1 An In alkaline carbonate soils, an ECe of 8 dS m or more at 25 °C if and a the pH (H2O) of the saturation extract is 8.5 or more is are very common in alkaline carbonate soils. Sombric horizon General description A sombric horizon (from French sombre, dark) is a dark-coloured subsurface horizon containing illuvial humus that is neither associated with Al nor dispersed by Na. Diagnostic criteria A sombric horizon: 1. has a lower Munsell colour value or chroma than the overlying horizon; and 2. has a base saturation (by 1 M NH4OAc) less than 50 percent; and 3. shows evidence of humus accumulation, by a higher organic carbon content with respect to the overlying horizon, or through illuvial humus on ped surfaces or in pores visible in thin sections; and 4. does not underlie an albic horizon; and 5. has a thickness of 15 cm or more. Field identification Dark They are found in dark-coloured subsoils, associated with cool and moist, well-drained soils of high plateaus and mountains in tropical and subtropical regions. They resemble buried horizons but, in contrast to many of these, sombric horizons more or less follow the shape of the surface.
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Relationships with some other diagnostic horizons Sombric horizons may form or have been formed in coincide with argic, cambic, ferralic or nitic horizons. Sombric horizons may resemble Uumbric, horizons, as well as the dark-coloured melanic and fulvic horizons of Andosols, form at the surface and, as such, are different from sombric horizons. Spodic horizons are differentiated from sombric horizons by their much higher CEC of the clay fraction. The humus-illuvial part of natric horizons has a base saturation (by 1 M NH4OAc) of more than 50 percent, which separates it from the sombric horizon. Spodic horizon General description The spodic horizon (from Greek spodos, wood ash) is a subsurface horizon that contains illuvial amorphous substances composed of organic matter and Al, or of illuvial Fe. The illuvial materials are characterized by a high pH-dependent charge, a relatively large surface area and high water retention. Diagnostic criteria A spodic horizon: 1. has a pH (1:1 in water) of less than 5.9 in 85 percent or more of the horizon, unless the soil is cultivated; and 2. has an organic carbon content of 0.5 percent or more or an optical density of the oxalate extract (ODOE) value of 0.25 or more, at least in some part of the horizon; and 3. has one or both of the following: a. an albic horizon directly overlying the spodic horizon and has, directly under the albic horizon, one of the following Munsell colours, when moist (crushed and smoothed sample): i. a hue of 5 YR or redder; or ii. a hue of 7.5 YR with a value of 5 or less and a chroma of 4 or less; or iii. a hue of 10 YR or neutral and a value and a chroma of 2 or less; or iv. a colour of 10 YR 3/1; or b. with or without an albic horizon, one of the colours listed above, or a hue of 7.5 YR, a value of 5 or less and chroma of 5 or 6, both when moist (crushed and smoothed sample), and one or more of the following: i. cementation by organic matter and Al with or without Fe, in 50 percent or more of the volume and a very firm or firmer consistency in the cemented part; or ii. 10 percent or more of the sand grains showing cracked coatings on sand grains covering 10 percent or more of the surface of the horizon; or 26 iii. 0.50 percent or more Alox + ½Feox and an overlying mineral horizon which has a value less than one-half that amount in an overlying mineral horizon; or iv. an ODOE value of 0.25 or more, and a value less than one-half that amount in an overlying mineral horizon; or v. 10 percent or more (by volume) Fe lamellae27 in a layer 25 cm or more thick; and 4. does not form part of a natric horizon; and 28 4 5. has a Cpy/OC and a Cf/Cpy of 0.5 or more if occurring under tephric material that meets the requirements of an albic horizon; and 6. has a thickness of 2.5 cm or more.
26 Alox and Feox: acid oxalate-extractable aluminium and iron, respectively (Blakemore, Searle and Daly, 1981), expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105 °C) basis. 27 Iron lamellae are non-cemented bands of illuvial iron less than 2.5 cm thick. 28 Cpy, Cf and OC are pyrophosphate-extractable C, fulvic acid C and organic C, respectively (Ito et al., 1991), expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105 °C) basis.
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Field identification A spodic horizon normally underlies an albic horizon and has brownish-black to reddish-brown colours. Spodic horizons can also be characterized by the presence of a thin iron pan, when weakly developed by the presence of organic pellets, or by the accumulation of Fe in lamellar form. Relationships with some other diagnostic horizons Spodic horizons are usually associated with albic horizons, which they underlie; there may be an anthric, hortic, plaggic, terric or umbric horizons at the surface above, with or without an albic horizon. Spodic horizons in volcanic materials may exhibit andic properties owing to the alumino- organic complexes as well. Spodic horizons in other Podzols may exhibit some charecteristics of the andic properties, but normally have a higher bulk density. For classification purposes the presence of a spodic horizon, unless buried deeper than 50 cm, is given preference over the occurrence of andic properties. Spodic horizons have at least twice as much the Alox + ½Feox percentages as overlying layers, such as an albic, anthric, hortic, plaggic, terric or umbric horizon. This criterion does not normally apply to non-spodic layers with andic properties in which the alumino-organic complexes are hardly mobile. Some layers with andic properties are covered by relatively young, light-coloured volcanic ejecta that fulfil the requirements of an albic horizon. Therefore, in a number of cases, analytical tests are needed in order to verify the difference between layers with andic properties and spodic horizons, in particular the Cpy to OC or Cf to Cpy ratio tests. Similar to many spodic horizons, sombric horizons also contain more organic matter than an overlying layer. They can be differentiated from each other by the clay mineralogy (kaolinite usually dominating in sombric horizons, whereas the clay fraction of spodic horizons commonly contains significant amounts of vermiculite and Al-interlayered chlorite) and the much higher CEC of the clay fraction in spodic horizons. Similarly, plinthic horizons, which contain large amounts of illuvial accumulated Fe, are dominated by kaolinitic clay minerals and, therefore, have a much lower CEC of the clay fraction than that of spodic horizons. Takyric horizon General description A takyric horizon (from Turkic languages takyr, barren land) is a heavy-textured surface horizon comprising a surface crust and a platy structured lower part. It occurs under arid conditions in periodically flooded soils. Diagnostic criteria A takyric horizon has: 1. aridic properties; and 2. a platy or massive structure; and 3. a surface crust that has all of the following: a. thickness enough that it does not curl entirely upon drying; and b. polygonal cracks extending 2 cm or more deep when the soil is dry; and c. sandy clay loam, clay loam, silty clay loam or finer texture; and d. very hard consistence when dry, and very plastic or very plastic and sticky or very sticky consistence when wet; and -1 e. an electrical conductivity (ECe) of the saturated extract of less than 4 dS m , or less than that of the layer immediately below the takyric horizon. Field identification Takyric horizons occur in depressions in arid regions, where surface water, rich in clay and silt but relatively low in soluble salts, accumulates and leaches the upper soil horizons. Periodic
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leaching of salt disperses clay and forms a thick, compact, fine-textured crust with prominent polygonal cracks when dry. The crust often contains more than 80 percent clay and silt. Relationships with some other diagnostic horizons Takyric horizons occur in association with many diagnostic horizons, the most important ones being the salic, gypsic, calcic and cambic horizons. The low EC and low soluble-salt content of takyric horizons set them apart from the salic horizon. Terric horizon General description A terric horizon (from Latin terra, earth) is a human-induced mineral surface horizon that develops through addition of earthy manures, compost, beach sands or mud over a long period of time. It builds up gradually and may contain stones, randomly sorted and distributed. Diagnostic criteria A terric horizon is a mineral surface horizon and: 1. has a colour related to the source material; and 2. contains less than 20 percent artefacts (by volume); and 3. has a base saturation (by 1 M NH4OAc) of 50 percent or more; and 4. occurs in locally raised land surfaces; and 5. does not show stratification but has an irregular textural differentiation; and 6. has a lithological discontinuity at its base; and 7. has a thickness of 20 cm or more. Field identification Soils with a terric horizon show a raised surface that may be inferred either from field observation or from historical records. The terric horizon is not homogeneous, but subhorizons are thoroughly mixed. It commonly contains artefacts such as pottery fragments, cultural debris and refuse, which are typically very small (less than 1 cm in diameter) and much abraded. Relationships with some other diagnostic horizons Few soil characteristics differentiate the terric and plaggic horizons from each other. Terric horizons commonly show a high biological activity, have a neutral to slightly alkaline soil reaction (pH [H2O] is normally more than 7.0), and may contain free lime, whereas plaggic horizons have an acid soil reaction. The colour of the terric horizon is strongly related to the source material. Buried soils may be observed at the base of the horizon although mixing can obscure the contact. Thionic horizon General description The thionic horizon (from Greek theion, sulphur) is an extremely acid subsurface horizon in which sulphuric acid is formed through oxidation of sulphides. Diagnostic criteria A thionic horizon has: 1. a pH (1:1 in water) of less than 4.0; and 2. one or more of the following: a. yellow jarosite or yellowish-brown schwertmannite mottles or coatings; or b. concentrations with a Munsell hue of 2.5 Y or yellower and a chroma of 6 or more, moist; or c. direct superposition on sulphidic material; or d. 0.05 percent (by mass) or more water-soluble sulphate; and 3. a thickness of 15 cm or more.
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Field identification Thionic horizons generally exhibit pale yellow jarosite or yellowish-brown schwertmannite mottles or coatings. Soil reaction is extremely acid; pH (H2O) of 3.5 is not uncommon. While mostly associated with recent sulphidic coastal sediments, thionic horizons also develop inland in sulphidic materials exposed by excavation or erosion. Relationships with some other diagnostic horizons The thionic horizon often underlies a strongly mottled horizon with pronounced redoximorphic features (reddish to reddish-brown iron hydroxide mottles and a light-coloured, Fe-depleted matrix). Umbric horizon General characteristics description The umbric horizon (from Latin umbra, shade) is a thick, dark-coloured, base-depleted surface horizon with a low base saturation and a moderate to high content of rich in organic matter. Diagnostic criteria An umbric horizon, after mixing either the upper 20 cm of the mineral soil or, if continuous rock, a cryic, petroduric or petroplinthic horizon is present within 20 cm of the mineral soil surface, the entire mineral soil above, has: 1. a soil structure sufficiently strong that the horizon is not both massive and hard or very hard when dry in both the mixed part and the underlying unmixed part, if the minimum thickness is larger than 20 cm (prisms larger than 30 cm in diameter are included in the meaning of massive if there is no secondary structure within the prisms); and 2. Munsell colours with a chroma of 3 or less when moist, a value of 3 or less when moist and 5 or less when dry, both on broken samples in both the mixed part and the underlying unmixed part, if the minimum thickness is greater than 20 cm. The colour value is one unit or more darker than that of the parent material unless the parent material has a colour value of 4 or less, moist, in which case the colour contrast requirement is waived. If a parent material is absent, comparison must be made with the layer immediately underlying the surface layer; and 3. an organic carbon content of 0.6 percent or more, in both the mixed part and the underlying unmixed part, if the minimum thickness is larger than 20 cm. The organic carbon content is at least 0.6 percent more than in the parent material if the colour requirements are waived because of dark coloured parent materials; and 4. a base saturation (by 1 M NH4OAc) of less than 50 percent on a weighted average throughout the depth of the horizon; and 5. a thickness of one of the following: a. 10 cm or more if directly overlying continuous rock, a cryic, petroplinthic or petroduric horizon; or b. 20 cm or more and one-third or more of the thickness between the mineral soil surface and the upper boundary of continuous rock, or a cryic, gypsic, petroduric, petrogypsic, petroplinthic or salic horizon or calcaric, fluvic or gypsiric material within 75 cm; or c. 20 cm or more and one-third or more of the thickness between the mineral soil surface and the lower boundary of the lowest diagnostic horizon within 75 cm and, if present, above any of the diagnostic horizons or materials listed under b.; or d. 25 cm or more. Field identification The main field characteristics of an umbric horizon are its dark colour and its structure. In general, umbric horizons tend to have a lesser grade of soil structure than mollic horizons.
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Most umbric horizons have an acid reaction (pH [H2O, 1:2.5] of less than about 5.5), which represents a base saturation of less than 50 percent. An additional indication for the acidity is a shallow, horizontal rooting pattern in the absence of a physical barrier. Relationships with some other diagnostic horizons The base saturation requirement sets the umbric horizon apart from the mollic horizon, which is otherwise very similar. The upper limit of organic carbon content varies from 12 percent (20 percent organic matter) to 18 percent (30 percent organic matter), which is the lower limit for the histic horizon, or 20 percent, the lower limit of a folic horizon. Some thick, dark-coloured, organic-rich, base-desaturated surface horizons occur, which are formed as a result of human activities, such as deep cultivation and manuring, the addition of organic manures, the presence of ancient settlements, and kitchen middens (anthragric, hortic, plaggic or terric horizons). These horizons can usually be recognized in the field by the presence of artefacts, spade marks, contrasting mineral inclusions or stratification indicating the intermittent addition of manurial material, a relative higher position in the landscape, or by checking the agricultural history of the area. Vertic horizon General description The vertic horizon (from Latin vertere, to turn) is a clayey subsurface horizon that, as a result of shrinking and swelling, has slickensides and wedge-shaped structural aggregates. Diagnostic criteria A vertic horizon: 1. contains 30 percent or more clay throughout; and 2. has wedge-shaped structural aggregates with a longitudinal axis tilted between 10 ° and 60 ° from the horizontal; and 3. has slickensides29; and 4. has a thickness of 25 cm or more. Field identification Vertic horizons are clayey, with a hard to very hard consistency. When dry, vertic horizons show cracks of 1 cm or more wide. Polished, shiny ped surfaces (slickensides), often at sharp angles, are distinctive. Additional characteristics The COLE is a measure for the shrink–swell potential and is defined as the ratio of the difference between the moist length and the dry length of a clod to its dry length: (Lm - Ld)/Ld, in which Lm is the length at 33 kPa tension and Ld the length when dry. In vertic horizons, the COLE is more than 0.06. Relationships with some other diagnostic horizons Several other diagnostic horizons may also have high clay contents, viz. the argic, natric and nitic horizons. These horizons lack the characteristic typical for the vertic horizon; however, they may be laterally linked in the landscape with the vertic horizon usually taking up the lowest position. Voronic horizon General description The voronic horizon (from Russian voronoj, black) is a special type of mollic horizon. It is a deep, well-structured, blackish surface horizon with a high base saturation, a high content of organic matter and a high biological activity.
29 Slickensides are polished and grooved ped surfaces that are produced by aggregates sliding one past another.
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Diagnostic criteria A voronic horizon is a mineral surface horizon and has: 1. granular or fine subangular blocky soil structure; and 2. Munsell colours with a chroma of less than 2.0 when moist, a value less than 2.0 when moist and less than 3.0 when dry on broken samples. If there is 40 percent or more finely divided lime, or if the texture of the horizon is loamy sand or coarser, the limits of colour value when dry are waived; the colour value when moist is 3.0 or less. The colour value is one unit or more darker than that of the parent material (both moist and dry), unless the parent material has a colour value less than 4.0, moist. If a parent material is not present, comparison must be made with the layer immediately underlying the surface layer. The above colour requirements apply to the upper 15 cm of the voronic horizon, or immediately below any plough layer; and 3. 50 percent or more (by volume) of the horizon consisting of worm burrows, worm casts, and filled burrows; and 4. an organic carbon content of 1.5 percent or more. The organic carbon content is 6 percent or more if the colour requirements are waived because of finely divided lime, or 1.5 percent more than in the parent material if the colour requirements are waived because of dark coloured parent materials; and 5. a base saturation (by 1 M NH4OAc) of 80 percent or more; and 6. a thickness of 35 cm or more. Field identification The voronic horizon is identified by its blackish colour, well-developed structure (usually granular), high activity of worms and other burrowing animals, and its thickness. Relationships with some other diagnostic horizons The voronic horizon is a special case of the mollic horizon with Its higher requirements for organic carbon content, the darkerness of colours required, the high biological contribution to the soil structure, and its greater minimum depth express the special character of the voronic horizon with respect to the mollic horizon. Yermic horizon General description The yermic horizon (from Spanish yermo, desert) is a surface horizon that usually, but not always, consists of surface accumulations of rock fragments (desert pavement) embedded in a loamy vesicular layer that may be covered by a thin aeolian sand or loess layer. Diagnostic criteria A yermic horizon has: 1. aridic properties; and 2. one or more of the following: a. a pavement that is varnished or includes wind-shaped gravel or stones (ventifacts); or b. a pavement associated with a vesicular layer; or c. a vesicular layer below a platy surface layer. Field identification A yermic horizon comprises a pavement and/or a vesicular layer that has a loamy texture. The vesicular layer shows a polygonal network of desiccation cracks, often filled with in-blown material, that extend into the underlying layers. The surface layers have a weak to moderate platy structure. Relationships with some other diagnostic horizons Yermic horizons often occur in association with other diagnostic horizons characteristic for desert environments (salic, gypsic, duric, calcic and cambic horizons). In very cold deserts (e.g. Antarctica), they may occur associated with cryic horizons. Under these conditions, coarse
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cryoclastic material dominates and there is little dust to be deflated and deposited by wind. Here, a dense pavement with varnish, ventifacts, aeolian sand layers and soluble mineral accumulations may occur directly on loose deposits, without a vesicular layer. DIAGNOSTIC PROPERTIES Abrupt textural change General description An abrupt textural change (from Latin abruptus) is a very sharp increase in clay content within a limited depth range. Diagnostic criteria An abrupt textural change requires 8 percent or more clay in the underlying layer and: 1. doubling of the clay content within 7.5 cm if the overlying layer has less than 20 percent clay; or 2. 20 percent (absolute) increase in clay content within 7.5 cm if the overlying layer has 20 percent or more clay. Albeluvic tonguing General description The term albeluvic tonguing (from Latin albus, white, and eluere, to wash out) is connotative of penetrations of clay- and Fe-depleted material into an argic horizon. When peds are present, albeluvic tongues occur along ped surfaces. Diagnostic criteria Albeluvic tongues: 1. have the colour of an albic horizon; and 2. have greater depth than width, with the following horizontal dimensions: a. 5 mm or more in clayey argic horizons; or b. 10 mm or more in clay loam and silty argic horizons; or c. 15 mm or more in coarser (silt loam, loam or sandy loam) argic horizons; and 3. occupy 10 percent or more of the volume in the first 10 cm of the argic horizon, measured on both vertical and horizontal sections; and 4. have a particle-size distribution matching that of the coarser textured horizon overlying the argic horizon. Andic properties General description Andic properties (from Japanese an, dark, and do, soil) result from moderate weathering of mainly pyroclastic deposits. However, some soils develop andic properties from non-volcanic materials (e.g. loess, argillite and ferralitic weathering products). The presence of short-range- order minerals and/or organo-metallic complexes is characteristic for andic properties. These minerals and complexes are commonly part of the weathering sequence in pyroclastic deposits (tephric soil material Æ vitric properties Æ andic properties). Andic properties may be found at the soil surface or in the subsurface, commonly occurring as layers. Many surface layers with andic properties contain a high amount of organic matter (more than 5 percent), are commonly very dark coloured (Munsell value and chroma, moist, are 3 or less), have a fluffy macrostructure and, in some places, a smeary consistence. They have a low bulk density and commonly have a silt loam or finer texture. Andic surface layers rich in organic matter may be very thick, having a thickness of 50 cm or more (pachic characteristic) in some soils. Andic subsurface layers are generally somewhat lighter coloured. Andic layers may have different characteristics, depending on the type of the dominant weathering process acting upon the soil material. They may exhibit thixotropy, i.e. the soil material changes, under pressure or by rubbing, from a plastic solid into a liquefied stage and
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back into the solid condition. In perhumid climates, humus-rich andic layers may contain more than twice the water content of samples that have been oven-dried and rewetted (hydric characteristic). Two major types of andic properties are recognized: one in which allophane and similar minerals are predominant (the sil-andic type); and one in which Al complexed by organic acids prevails (the alu-andic type). The sil-andic property typically gives a strongly acid to neutral soil reaction, while the alu-andic property gives an extremely acid to acid reaction. Diagnostic criteria Andic properties30 require: 31 1. an Alox + ½Feox value of 2.0 percent or more; and 2. a bulk density32 of 0.90 kg dm-3 or less; and 3. a phosphate retention of 85 percent or more; and 4. if occurring under tephric material that meets the requirements of an albic horizon, a 33 4 Cpy/OC or a Cf/Cpy of less than 0.5; and 4. less than 25 percent (by mass) organic carbon. Andic properties may be divided into sil-andic and alu-andic properties. Sil-andic properties show an acid-oxalate (pH 3) extractable silica (Siox) content of 0.6 percent or more or an 34 Alpy /Alox of less than 0.5; alu-andic properties show a Siox content of less than 0.6 percent and an Alpy/Al ox of 0.5 or more. Transitional alu-sil-andic properties that show a Siox content between 0.6 and 0.9 percent and an Alpy/Al ox between 0.3 and 0.5 may occur (Poulenard and Herbillon, 2000). Field identification Andic properties may be identified using the sodium fluoride field test of Fieldes and Perrott (1966). A pH in NaF of more than 9.5 indicates allophane and/or organo-aluminium complexes. The test is indicative for most layers with andic properties, except for those very rich in organic matter. However, the same reaction occurs in spodic horizons and in certain acid clays that are rich in Al-interlayered clay minerals. Uncultivated, organic matter-rich surface layers with sil-andic properties typically have a pH (H2O) of 4.5 or higher, while uncultivated surface layers with alu-andic properties and rich in organic matter typically have a pH (H2O) of less than 4.5. Generally, pH (H2O) in sil-andic subsoil layers is more than 5.0. Relationships with some diagnostic horizons and properties Vitric properties are distinguished from andic properties by a lesser degree of weathering. This is typically evidenced by a lower amount of non-crystalline or paracrystalline pedogenetic minerals, as characterized by the a moderate amount of acid oxalate (pH 3) extractable Al and Fe in layers with vitric properties (Alox + ½Feox = 0.4–2.0 percent), by a higher bulk density (BD > 0.9 kg dm-3), or by a lower phosphate retention (25 – <85 percent). Histic or folic horizons with less than 25 percent organic carbon may have andic properties. In organic layers with 25 percent or more organic carbon, andic properties are not considered. Spodic horizons, which also contain complexes of sesquioxides and organic substances, can have similar characteristics to those of layers with exhibit andic properties as well. rich in alumino-organic complexes. Many spodic horizons have at least twice as much Alox + ½Feox as
30 Shoji et al., 1996; Takahashi, Nanzyo and Shoji, 2004. 31 Alox and Feox are acid oxalate-extractable aluminium and iron, respectively (Blakemore, Searle and Daly, 1981), expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105 °C) basis. 32 For bulk density, the volume is determined after an undried soil sample has been desorbed at 33 kPa (no prior drying) and afterwards weighed oven-dried (see Annex 1). 33 Cpy, Cf and OC are pyrophosphate-extractable C, fulvic acid C and organic C, respectively (Ito et al., 1991), expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105 °C) basis. 34 Alpy: pyrophosphate-extractable aluminium, expressed as percent of the fine earth (0–2 mm) fraction on an oven- dried (105 °C) basis.
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an overlying layer. This normally does not apply to layers with andic properties in which the alumino-organic complexes are virtually immobile. However, particularly in Podzols to which the Entic qualifier applies and which have a spodic horizon without the requirement of at least twice as much Alox + ½Feox as an overlying layer, other diagnostic criteria such as the bulk density are needed in order to discriminate between layers with andic properties and spodic horizons. Some layers with andic properties are covered by relatively young, light-coloured volcanic ejecta that are difficult to distinguish from an albic horizon. Therefore, in a number of cases, analytical tests are needed in order to verify the difference between layers with andic properties and spodic horizons, in particular the Cpy to OC or Cf to Cpy ratio tests. Aridic properties General description The term aridic properties (from Latin aridus, dry) combines a number of properties that are common in surface horizons of soils occurring under arid conditions and where pedogenesis exceeds new accumulation at the soil surface by aeolian or alluvial activity. Diagnostic criteria Aridic properties require all of the following: 1. an organic carbon content of less than 0.6 percent35 if the texture is sandy loam or finer, or less than 0.2 percent if the texture is coarser than sandy loam, as a weighted average in the upper 20 cm of the soil or down to the top of a diagnostic subsurface horizon, a cemented layer, or to continuous rock, whichever is shallower; and 2. evidence of aeolian activity in one or more of the following forms: a. the sand fraction in some layer or in in-blown material filling cracks contains rounded or subangular sand particles showing a matt surface (use a ×10 hand-lens). These particles make up 10 percent or more of the medium and coarser quartz sand fraction; or b. wind-shaped rock fragments (ventifacts) at the surface; or c. aeroturbation (e.g. cross-bedding); or d. evidence of wind erosion or deposition; and 2. both broken and crushed samples with a Munsell colour value of 3 or more when moist and 4.5 or more when dry, and a chroma of 2 or more when moist; and 3. a base saturation (by 1 M NH4OAc) of 75 percent or more. Additional remarks The presence of acicular (needle-shaped) clay minerals (e.g. sepiolite and palygorskite) in soils is considered connotative of a desert environment, but it has not been reported in all desert soils. This may be due either to the fact that, under arid conditions, acicular clays are not produced but only preserved, provided they exist in the parent material or in the dust that falls on the soil, or that, in some desert environments, there has not been sufficient weathering to produce detectable quantities of secondary clay minerals. Continuous rock Definition Continuous rock is consolidated material underlying the soil, exclusive of cemented pedogenetic horizons such as petrocalcic, petroduric, petrogypsic and petroplinthic horizons. Continuous rock is sufficiently consolidated to remain intact when an air-dried specimen 25– 30 mm on a side is submerged in water for 1 hour. The material is considered continuous only if cracks into which roots can enter are on average 10 cm or more apart and occupy less than
35 -1 The organic carbon content may be higher if the soil is periodically flooded, or if it has an ECe of 4 dS m or more somewhere within 100 cm of the soil surface.
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20 percent (by volume) of the continuous rock, with no significant displacement of the rock having taken place. Ferralic properties General description Ferralic properties (from Latin ferrum, iron, and alumen, alum) refer to mineral soil material that has a relatively low CEC. It also includes soil materials that fulfil the requirements of a ferralic horizon except texture. Diagnostic criteria Ferralic properties require in some subsurface layer: -1 36 1. a CEC (by 1 M NH4OAc) of less than 24 cmolc kg clay ; or -1 2. a CEC (by 1 M NH4OAc) of less than 4 cmolc kg soil and a Munsell chroma of 5 or more, moist. Geric properties General description Geric properties (from Greek geraios, old) refer to mineral soil material that has a very low ECEC or even acts as an anion exchanger. Diagnostic criteria Geric properties require: 1. an ECEC (sum of exchangeable bases plus exchangeable acidity in 1 M KCl) of less than -1 37 1.5 cmolc kg clay ; or 2. a delta pH (pHKCl minus pHwater) of +0.1 or more. Gleyic colour pattern General description Soil materials develop a gleyic colour pattern (from Russian gley, mucky soil mass) if they are saturated with groundwater (or were saturated in the past, if now drained), unless drained, for a period that allows reducing conditions to occur (this may range from a few days in the tropics to a few weeks in other areas), and show a gleyic colour pattern. Diagnostic criteria A gleyic colour pattern shows one or both of the following: 1. 90 percent or more (exposed area) reductimorphic colours, which comprise neutral white to black (Munsell hue N1/ to N8/) or bluish to greenish (Munsell hue 2.5 Y, 5 Y, 5 G, 5 B); or 2. 5 percent or more (exposed area) mottles of oximorphic colours, which comprise any colour, excluding reductimorphic colours. Field identification A gleyic colour pattern results from a redox gradient between groundwater and capillary fringe causing an uneven distribution of iron and manganese (hydr)oxides. In the lower part of the soil and/or inside the peds, the oxides are either transformed into insoluble Fe/Mn(II) compounds or they are translocated; both processes lead to the absence of colours with a hue redder than 2.5 Y. Translocated Fe and Mn compounds can be concentrated in the oxidized form (Fe[III], Mn[IV]) on ped surfaces or in biopores (rusty root channels), and towards the surface even in the matrix. Manganese concentrations can be recognized by strong effervescence using a 10-percent H2O2 solution. Reductimorphic colours reflect permanently wet conditions. In loamy and clayey material, blue-green colours dominate owing to Fe (II, III) hydroxy salts (green rust). If the material is
36 See Annex 1. 37 See Annex 1.
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rich in sulphur (S), blackish colours prevail owing to colloidal iron sulphides such as greigite or mackinawite (easily recognized by smell after applying 1 M HCl). In calcareous material, whitish colours are dominant owing to calcite and/or siderite. Sands are usually light grey to white in colour and often also impoverished in Fe and Mn. Bluish-green and black colours are unstable and often oxidize to a reddish brown within a few hours of exposure to air. The upper part of a reductimorphic layer may show up to 10 percent rusty colours, mainly around channels of burrowing animals or plant roots. Oximorphic colours reflect alternating reducing and oxidizing conditions, as is the case in the capillary fringe and in the surface horizons of soils with fluctuating groundwater levels. Specific colours indicate ferrihydrite (reddish brown), goethite (bright yellowish brown), lepidocrocite (orange), and jarosite (pale yellow). In loamy and clayey soils, the iron oxides/hydroxides are concentrated on aggregate surfaces and the walls of larger pores (e.g. old root channels). Additional characteristics If a layer has a gleyic colour pattern in 50 percent of its volume, the layer has in the other 50 percent a matrix of oximorphic colours, i.e. neither reductimorphic colours nor mottles of oximorphic colours. Lithological discontinuity General description Lithological discontinuities (from Greek lithos, stone, and Latin continuare, to continue) are significant changes in particle-size distribution or mineralogy that represent differences in lithology within a soil. A lithological discontinuity can also denote an age difference. Diagnostic criteria A lithological discontinuity requires one or more of the following: 1. an abrupt change in particle-size distribution that is not solely associated with a change in clay content resulting from pedogenesis; or 2. a relative change of 20 percent or more in the ratios between coarse sand, medium sand, and fine sand; or 3. rock fragments that do not have the same lithology as the underlying continuous rock; or 4. a layer containing rock fragments without weathering rinds overlying a layer containing rocks with weathering rinds; or 5. layers with angular rock fragments overlying or underlying layers with rounded rock fragments; or 6. abrupt changes in colour not resulting from pedogenesis; or 7. marked differences in size and shape of resistant minerals between superimposed layers (as shown by micromorphological or mineralogical methods). Additional characteristics In cases, a horizontal line of rock fragments (stone line) overlying and underlying layers with smaller amounts or of rock fragments or a decreasing percentage of rock fragments with increasing depth may also be suggestive of a lithological discontinuity, although the sorting action of small fauna such as termites can produce similar effects in what would initially have been lithologically uniform parent material. Reducing conditions Definition Reducing conditions (from Latin reducere) show one or more of the following: 1. a negative logarithm of the hydrogen partial pressure (rH) of less than 20; or
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2. the presence of free Fe2+, as shown on a freshly broken and smoothed surface of a field- wet soil by the appearance of a strong red colour after wetting it with a 0.2-percent α,α, dipyridyl solution in 10-percent acetic acid38; or 3. the presence of iron sulphide; or 4. the presence of methane. Secondary carbonates General description The term secondary carbonates (from Latin carbo, coal) refers to translocated lime, precipitated in place from the soil solution rather than inherited from a soil parent material. As a diagnostic property, it should be present in significant quantities. Field identification Secondary carbonates either may disrupt the soil structure or fabric, forming masses, nodules, concretions or spheroidal aggregates (white eyes) that are soft and powdery when dry, or may be present as soft coatings in pores, on structural faces or on the undersides of rock or cemented fragments. If present as coatings, secondary carbonates cover 50 percent or more of the structural faces and are thick enough to be visible when moist. If present as soft nodules, they occupy 5 percent or more of the soil volume. Filaments (pseudomycelia) are only included in the definition of secondary carbonates if they are permanent and do not come and go with changing moisture conditions. This can be checked by spraying some water. Stagnic colour pattern General description Soil materials develop has a stagnic colour pattern (from Latin stagnare, to stagnate) if it is they are, at least temporarily, saturated with surface water, unless drained, (or were saturated in the past, if now drained) for a period long enough that to allows reducing conditions to occur (this may range from a few days in the tropics to a few weeks in other areas). Diagnostic criteria A stagnic colour pattern shows mottling in such a way that the surfaces of the peds (or parts of the soil matrix) are lighter (at least one Munsell value unit more) and paler (at least one chroma unit less), and the interiors of the peds (or parts of the soil matrix) are more reddish (at least one hue unit) and brighter (at least one chroma unit more) than the non-redoximorphic parts of the layer, or than the mixed average of the interior and surface parts. Additional characteristics If a layer has a stagnic colour pattern in 50 percent of its volume the other 50 percent of the layer are non-redoximorphic (neither lighter and paler nor more reddish and brighter). Vertic properties Diagnostic criteria Soil material with vertic properties (from Latin vertere, to turn) has one or both of the following: 1. 30 percent or more clay throughout a thickness of 15 cm or more and one or both of the following: a. slickensides or wedge-shaped aggregates; or b. cracks that open and close periodically and are 1 cm or more wide; or 2. a COLE of 0.06 or more averaged over depth of 100 cm from the soil surface.
38 This test may not give the strong red colour in soil materials with a neutral or alkaline soil reaction.
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Vitric properties General description Vitric properties (from Latin vitrum, glass) apply to layers with volcanic glass and other primary minerals derived from volcanic ejecta and which contain a limited amount of short-range-order minerals or organo-metallic complexes. Diagnostic criteria Vitric properties39 require: 1. require 5 percent or more (by grain count) volcanic glass, glassy aggregates and other glass-coated primary minerals, in the fraction between 0.05 and 2 mm, or in the fraction between 0.02 and 0.25 mm; and 40 2. require an Alox + ½Feox value of 0.4 percent or more; and 3. require a phosphate retention of 25 percent or more; and 4. do not meet one or more of the criteria of the andic properties; and 5. if occurring under tephric material that meets the requirements of an albic horizon, a 41 4 Cpy/OC or a Cf/Cpy of less than 0.5; and 5. require less than 25 percent (by mass) organic carbon. Field identification Vitric properties can occur in a surface layer. However, they can also occur under some tens of centimetres of recent pyroclastic deposits. Layers with vitric properties can have an appreciable amount of organic matter. The sand and coarse silt fractions of layers with vitric properties have a significant amount of unaltered or partially altered volcanic glass, glassy aggregates and other glass-coated primary minerals (coarser fractions may be checked by ×10 hand-lens; finer fractions may be checked by microscope). Relationships with some diagnostic horizons, properties and materials Vitric properties are, on the one hand, closely linked with andic properties, into which they may eventually develop. On the other hand, layers with vitric properties develop from tephric materials. Mollic and umbric horizons may exhibit vitric properties as well. DIAGNOSTIC MATERIALS Artefacts Definition Artefacts (from Latin ars, art, and facere, to make) are solid or liquid substances that are: 1. one or both of the following: a. created or substantially modified by humans as part of an industrial or artisanal manufacturing process; or b. brought to the surface by human activity from a depth where they were not influenced by surface processes, with properties substantially different from the environment where they are placed; and 2. have substantially the same properties as when first manufactured, modified or excavated. Examples of artefacts are bricks, pottery, glass, crushed or dressed stone, industrial waste, garbage, processed oil products, mine spoil and crude oil.
39 Adapted after Takahashi, Nanzyo and Shoji (2004) and findings of the COST 622 Action. 40 Alox and Feox are acid oxalate-extractable aluminium and iron, respectively (Blakemore, Searle and Daly, 1987), expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105 °C) basis. 41 Cpy, Cf and OC are pyrophosphate-extractable C, fulvic acid C and organic C, respectively (Ito et al., 1991), expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105 °C) basis.
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Calcaric material Definition Calcaric material (from Latin calcarius) effervescences strongly with 1 M HCl in most of the fine earth. It applies to material that contains 2 percent or more calcium carbonate equivalent. Colluvic material General description Colluvic material (from Latin colluerevio, to wash mixture) material is formed by sedimentation through human-induced erosion. It normally accumulates in foot slope positions, in depressions or above hedge walls. The erosion may have taken place since Neolithic times. Field identification The upper part of the colluvic material shows characteristics (texture, colour, pH and organic carbon content) similar to the surface layer of the source in the neighbourhood. Many colluvic materials have artefacts such as pieces of bricks, ceramics and glass. Stratification is common although not always easily detectable, and many colluvic materials have a lithological discontinuity at their base. Fluvic material General description Fluvic material (from Latin fluvius, river) refers to fluviatile, marine and lacustrine sediments that receive fresh material at regular intervals or have received it in the recent past42. Diagnostic criteria Fluvic material is of fluviatile, marine or lacustrine origin that shows stratification in at least 25 percent of the soil volume over a specified depth; stratification may also be evident from an organic carbon content decreasing irregularly with depth, or remaining above 0.2 percent to a depth of 100 cm from the mineral soil surface. Thin strata of sand may have less organic carbon if the finer sediments below meet the latter requirement. Field identification Stratification, taking such forms as alternating darker coloured soil layers, reflects an irregular decrease in organic carbon content with depth. Fluvic material is always associated with organized water bodies and should be distinguished from colluvial deposits (sheet colluvia, splays and colluvial cones), even though they look very much the same. Gypsiric material Definition Gypsiric material (from Greek gypsos) is mineral material that contains 5 percent or more gypsum (by volume). Limnic material Diagnostic criteria Limnic material (from Greek limnae, pool) includes both organic and mineral materials that are: 1. deposited in water by precipitation or through action of aquatic organisms, such as diatoms and other algae; or 2. derived from underwater and floating aquatic plants and subsequently modified by aquatic animals.
42 Recent past covers the period during which the soil has been protected from flooding, e.g. by empoldering, embanking, canalization or artificial drainage, and during which time soil formation has not resulted in the development of any diagnostic subsurface horizon apart from a salic or sulphuric thionic horizon.
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Field identification Limnic material occurs as subaquatic deposits (or at the surface after drainage). Four types of limnic material are distinguished: 1. Coprogenous earth or sedimentary peat: dominantly organic, identifiable through many faecal pellets, Munsell colour value (moist) 4 or less, slightly viscous water suspension, non- or slightly plastic and non-sticky consistence, shrinking upon drying, difficult to rewet after drying, and cracking along horizontal planes. 2. Diatomaceous earth: mainly diatoms (siliceous), identifiable by irreversible changing of the matrix colour (Munsell value 3, 4 or 5 in field moist or wet condition) as a result of the irreversibly shrinkage of the organic coatings on diatoms (use 440× microscope). 3. Marl: strongly calcareous, identifiable by a Munsell colour value, moist, of 5 or more, and a reaction with 10-percent 1 M HCl. The colour of marl does not usually change upon drying. 4. Gyttja: small coprogenic aggregates of strongly humified organic matter and minerals of predominantly clay to silt size, 0.5 percent or more organic carbon, a Munsell colour hue of 5 Y, GY or G, strong shrinkage after drainage and an rH value of 13 or more. Mineral material General description In mineral material (from Celtic mine, mineral), the soil properties are dominated by mineral components. Diagnostic criteria Mineral material has one or both of the following: 1. less than 20 percent organic carbon in the fine earth (by mass) if saturated with water for less than 30 consecutive days in most years without being drained; or 2. one or both of the following: a. less than (12 + [clay percentage of the mineral fraction × 0.1]) percent organic carbon in the fine earth (by mass),;or b. less than 18 percent organic carbon in the fine earth (by mass), if the mineral fraction has 60 percent or more clay. Organic material General description Organic material (from Greek organon, tool) consists of a large amount of organic debris that accumulates at the surface under either wet or dry conditions and in which the mineral component does not significantly influence the soil properties. Diagnostic criteria Organic material has one or both of the following: 1. 20 percent or more organic carbon in the fine earth (by mass); or 2. if saturated with water for 30 consecutive days or more in most years (unless drained), one or both of the following: a. (12 + [clay percentage of the mineral fraction × 0.1]) percent or more organic carbon in the fine earth (by mass),; or b. 18 percent or more organic carbon in the fine earth (by mass). Ornithogenic material General description Ornithogenic material (from Greek ornithos, bird, and genesis, origin) is material with strong influence of bird excrement. It often has a high content of gravel that has been transported by birds.
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Diagnostic criteria Ornithogenic material has: 1. remnants of birds or bird activity (bones, feathers, and sorted gravel of similar size); and 2. a P2O5 content of 0.25 percent or more in 1-percent citric acid. Sulphidic material General description Sulphidic material (from English sulphide) is a waterlogged deposit containing S, mostly in the form of sulphides, and only moderate amounts of calcium carbonate. Diagnostic criteria Sulphidic material has: 1. a pH (1:1 in water) of 4.0 or more and 0.75 percent or more S (dry mass) and less than three times as much calcium carbonate equivalent as S; or 2. a pH (1:1 in water) of 4.0 or more that, if the material is incubated as a layer 1 cm thick, at field capacity at room temperature, drops 0.5 or more units to a pH of 4.0 or less (1:1 in water) within 8 weeks. pH (1:1 in water) of 4.0 or more. Field identification In moist or wet conditions, deposits containing sulphides often show a golden shine, the colour of pyrite. Forced oxidation with a 30-percent hydrogen peroxide solution lowers the pH to 2.5 or less, the reaction may be vigorous in sunlight or on heating. Munsell colours range: hues of N, 5 Y, 5 GY, 5 BG, or 5 G; values of 2, 3 or 4; chroma always 1. The colour is usually unstable, and blackens upon exposure. Sulphidic clay is usually practically unripe. If the soil is disturbed, a whiff of rotten eggs may be noticed. This is accentuated by application of 1 M HCl. Technic hard rock Definition Technic hard rock (from Greek technikos, skilfully made or constructed) is consolidated material resulting from an industrial process, with properties substantially different from those of natural materials. Tephric material General description Tephric material43 (from Greek tephra, pile ash) consists either of tephra, i.e. unconsolidated, non- or only slightly weathered primary pyroclastic products of volcanic eruptions (including ash, cinders, lapilli, pumice, pumice-like vesicular pyroclastics, blocks and volcanic bombs), or of tephric deposits, i.e. tephra that has been reworked and mixed with material from other sources. This includes tephric loess, tephric blown sand and volcanogenic alluvium. Diagnostic criteria Tephric material has: 1. 30 percent or more (by grain count) volcanic glass, glassy aggregates and other glass- coated primary minerals, glassy materials, and glassy aggregates in the fraction between 0.02–2 mm particle-size fraction; and 2. no andic or vitric properties. Relationships with some diagnostic horizons properties Progressive weathering of tephric material will develop vitric properties; it is then no longer regarded as tephric material. The low amount of acid oxalate extractable Al and Fe sets tephric material apart from layers with vitric or andic properties.
43 Description and diagnostic criteria are adapted from Hewitt (1992).
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Chapter 3 Key to the Reference Soil Groups of the WRB with lists of prefix and suffix qualifiers
Before using the key, please read “Rules for classification”, page 8 and 9.
Key to the Reference Soil Groups Prefix qualifiers Suffix qualifiers Soils having organic material, either Folic Thionic 1. 10 cm or more thick starting at the soil surface and Limnic Ornithic immediately overlying ice, continuous rock, or fragmental Lignic Calcaric materials, the interstices of which are filled with organic Fibric Sodic material; or Hemic Alcalic 2. cumulatively within 100 cm of the soil surface either 60 cm or more thick if 75 percent (by volume) or more of Sapric Toxic the material consists of moss fibres or 40 cm or more Floatic Dystric thick in other materials and starting within 40 cm of the Subaquatic Eutric soil surface. Glacic Turbic HISTOSOLS Ombric Gelic Rheic Petrogleyic Technic Placic Cryic Skeletic Hyperskeletic Tidalic Leptic Drainic Vitric Transportic Andic Novic Salic Calcic
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Key to the Reference Soil Groups Prefix qualifiers Suffix qualifiers Other soils having Hydragric Sodic 1. either a hortic, irragric, plaggic or terric horizon 50 cm or Irragric Alcalic more thick; or Terric Dystric 2. an anthraquic horizon and an underlying hydragric Plaggic Eutric horizon with a combined thickness of 50 cm or more. Hortic Oxyaquic ANTHROSOLS Escalic Arenic
Technic Siltic Fluvic Clayic Salic Novic Gleyic Stagnic Spodic Ferralic Stagnic Regic Other soils having Ekranic Calcaric 1. 20 percent or more (by volume, by weighted average) Linic Ruptic artefacts in the upper 100 cm from the soil surface or to Urbic Toxic continuous rock or a cemented or indurated layer, Spolic Reductic whichever is shallower; or Garbic Humic 2. a continuous, very slowly permeable to impermeable, constructed geomembrane of any thickness starting within Folic Densic 100 cm of the soil surface; or Histic Oxyaquic 3. technic hard rock starting within 5 cm of the soil surface Cryic Densic and covering 95 percent or more of the horizontal extent Leptic Skeletic of the soil. Fluvic Arenic 1 TECHNOSOLS Gleyic Siltic Vitric Clayic Stagnic Drainic Mollic Novic Alic Acric Luvic Lixic Umbric Other soils having Glacic Gypsiric 1. a cryic horizon starting within 100 cm of the soil surface; Turbic Calcaric or Folic Ornithic 2. a cryic horizon starting within 200 cm of the soil surface Histic Dystric and evidence of cryoturbation2 in some layer within Technic Eutric 100 cm of the soil surface. Hyperskeletic Reductaquic CRYOSOLS Leptic Oxyaquic
Natric Thixotropic Salic Aridic Vitric Skeletic Spodic Arenic Mollic Siltic Calcic Clayic Umbric Drainic Cambic Transportic Haplic Novic
1 Buried layers occur frequently in this RSG and can be indicated with the specifier Thapto- followed by a qualifer or a RSG. 2 Evidence of cryoturbation includes frost heave, cryogenic sorting, thermal cracking, ice segregation, patterned ground, etc.
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Key to the Reference Soil Groups Prefix qualifiers Suffix qualifiers Other soils having Nudilithic Brunic 1. one of the following: Lithic Gypsiric a. limitation of depth by continuous rock within 25 cm Hyperskeletic Calcaric of the soil surface; or Rendzic Ornithic b. less than 20 percent (by volume) fine earth Folic Tephric averaged over a depth of 75 cm from the soil surface or to Histic Protothionic continuous rock, whichever is shallower; and Technic Humic 2. no calcic, gypsic, petrocalcic, petrogypsic or spodic horizon. Vertic Sodic LEPTOSOLS Salic Dystric Gleyic Eutric Vitric Oxyaquic Andic Gelic Stagnic Placic Mollic Greyic Umbric Yermic Cambic Aridic Haplic Skeletic Drainic Novic Other soils having Grumic Thionic 1. a vertic horizon starting within 100 cm of the soil surface; Mazic Albic and Technic Manganesic 2. after the upper 20 cm have been mixed, 30 percent or Endoleptic Manganiferric more clay between the soil surface and the vertic horizon Salic Ferric throughout; and Gleyic Gypsiric 3. cracks1 that open and close periodically. Sodic Calcaric VERTISOLS Stagnic Humic Mollic Hyposalic Gypsic Hyposodic Duric Mesotrophic Calcic Hypereutric Haplic Pellic Chromic Novic
1 A crack is a separation between big blocks of soil. If the surface is self-mulching, or if the soil is cultivated while cracks are open, the cracks may be filled mainly by granular materials from the soil surface but they are open in the sense that the blocks are separated; it controls the infiltration and percolation of water. If the soil is irrigated, the upper 50 cm has a COLE of 0.06 or more.
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Key to the Reference Soil Groups Prefix qualifiers Suffix qualifiers Other soils having Subaquatic Thionic 1. fluvic material starting within 25 cm of the soil surface or Tidalic Anthric starting immediately below a plough layer of any depth Limnic Gypsiric and continuing to a depth of 50 cm or more or starting at Folic Calcaric the lower limit of a plough layer and continuing to a depth of 50 cm or more; and Histic Tephric 2. no argic, cambic, natric, petroplinthic or plinthic horizon Technic Petrogleyic starting within 50 cm of the soil surface; and Salic Gelic 3. no layers with andic or vitric properties with a combined Gleyic Oxyaquic thickness of 30 cm or more within 100 cm of the soil Stagnic Humic surface and starting within 25 cm of the soil surface. Mollic Sodic 1 FLUVISOLS Gypsic Dystric Calcic Eutric Umbric Greyic Haplic Takyric Yermic Aridic Densic Skeletic Arenic Siltic Clayic Drainic Transportic Other soils having a natric horizon starting within 100 cm of the soil Technic Glossalbic surface. Vertic Albic SOLONETZ Gleyic Abruptic Salic Colluvic Stagnic Ruptic Mollic Magnesic Gypsic Humic Duric Oxyaquic Petrocalcic Takyric Calcic Yermic Haplic Aridic Arenic Siltic Clayic Transportic Novic
1 Buried layers occur frequently in this RSG and can be indicated with the specifier Thapto- followed by a qualifer or a RSG.
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Key to the Reference Soil Groups Prefix qualifiers Suffix qualifiers Other soils having Petrosalic Sodic 1. a salic horizon starting within 50 cm of the soil surface; Hypersalic Aceric and Puffic Chloridic 2. no thionic horizon starting within 50 cm of the soil surface. Folic Sulphatic SOLONCHAKS Histic Carbonatic Technic Gelic Vertic Oxyaquic Gleyic Takyric Stagnic Yermic Mollic Aridic Gypsic Densic Duric Arenic Calcic Siltic Haplic Clayic Drainic Transportic Novic
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Key to the Reference Soil Groups Prefix qualifiers Suffix qualifiers Other soils having Folic Thionic 1. within 50 cm of the mineral soil surface a layer, 25 cm or Histic Abruptic more thick, that has in some parts reducing conditions in Anthraquic Calcaric some parts and in half or more of the soil volume a gleyic Technic Tephric colour pattern throughout; and Fluvic Colluvic 2. no layers with andic or vitric properties with a combined thickness of either Endosalic Humic a. 30 cm or more within 100 cm of the soil surface Vitric Sodic and starting within 25 cm of the soil surface; or Andic Alcalic b. 60 percent or more of the entire thickness of the Spodic Alumic soil when continuous rock or a cemented or Plinthic Toxic indurated layer is starting between 25 and Mollic Dystric 50 cm from the soil surface. Gypsic Eutric GLEYSOLS Calcic Petrogleyic
Alic Turbic Acric Gelic Luvic Greyic Lixic Takyric Umbric Arenic Haplic Siltic Clayic Drainic Novic Other soils having Vitric Anthric 1. one or more layers with andic or vitric properties with a Aluandic Fragic combined thickness of either Eutrosilic Calcaric a. 30 cm or more within 100 cm of the soil surface Silandic Colluvic and starting within 25 cm of the soil surface; or Melanic Acroxic b. 60 percent or more of the entire thickness of the Fulvic Sodic soil when continuous rock or a cemented or indurated layer is starting between 25 and Hydric Dystric 50 cm from the soil surface; and Folic Eutric 2. no argic, ferralic, petroplinthic, pisoplinthic, plinthic or Histic Turbic spodic horizon (unless buried deeper than 50 cm) Technic Gelic 1 ANDOSOLS Leptic Oxyaquic Gleyic Placic Mollic Greyic Gypsic Thixotropic Petroduric Skeletic Duric Arenic Calcic Siltic Umbric Clayic Haplic Drainic Transportic Novic
1 Buried layers occur frequently in this RSG and can be indicated with the specifier Thapto- followed by a qualifer or a RSG.
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Key to the Reference Soil Groups Prefix qualifiers Suffix qualifiers Other soils having a spodic horizon starting within 200 cm of the Placic Hortic mineral soil surface. Ortsteinic Plaggic PODZOLS Carbic Terric Rustic Anthric Entic Ornithic Albic Fragic Folic Ruptic Histic Turbic Technic Gelic Hyperskeletic Oxyaquic Leptic Lamellic Gleyic Densic Vitric Skeletic Andic Drainic Stagnic Transportic Umbric Novic Haplic Other soils having either Petric Albic 1. a plinthic, petroplinthic or pisoplinthic horizon starting Fractipetric Manganiferric within 50 cm of the soil surface; or Pisolithic Ferric 2. a plinthic horizon starting within 100 cm of the soil surface Gibbsic Endoduric and, directly above, a layer 10 cm or more thick, that has Posic Abruptic in some parts reducing conditions for some time during the year and in half or more of the soil volume, single or in Geric Colluvic combination Vetic Ruptic a. a stagnic colour pattern; or Folic Alumic b. an albic horizon. Histic Humic Technic Dystric PLINTHOSOLS Stagnic Eutric Acric Oxyaquic Lixic Pachic Umbric Umbriglossic Haplic Arenic Siltic Clayic Drainic Transportic Novic Other soils having Vetic Humic 1. a nitic horizon starting within 100 cm of the soil surface; Technic Alumic and Andic Dystric 1 2. gradual to diffuse horizon boundaries between the soil Ferralic Eutric surface and the nitic horizon; and Mollic Oxyaquic 3. no ferric, petroplinthic, pisoplinthic, plinthic or vertic Alic Colluvic horizon starting within 100 cm of the soil surface; and Acric Densic 4. no gleyic or stagnic colour pattern starting within 100 cm of the soil surface. Luvic Rhodic NITISOLS Lixic Transportic Umbric Novic Haplic
1 As defined in FAO (2006).
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Key to the Reference Soil Groups Prefix qualifiers Suffix qualifiers Other soils having Gibbsic Sombric 1. a ferralic horizon starting within 150 cm of the soil surface; Posic Manganiferric and Geric Ferric 2. no argic horizon that has, in the upper 30 cm, 10 percent Vetic Colluvic or more water-dispersible clay unless the upper 30 cm of Folic Humic the argic horizon has one or both of the following: Technic Alumic a. geric properties; or Andic Dystric b. 1.4 percent or more organic carbon. Fractiplinthic Eutric FERRALSOLS Petroplinthic Ruptic Pisoplinthic Oxyaquic Plinthic Densic Mollic Arenic Acric Siltic Lixic Clayic Umbric Rhodic Haplic Xanthic Transportic Novic Other soils having Solodic Thionic 1. an abrupt textural change within 100 cm of the soil surface Folic Albic and, directly above or below, a layer 5 cm or more thick, that Histic Manganiferric has in some parts reducing conditions for some time during the Technic Ferric year and in half or more of the soil volume, single or in combination Vertic Geric a. a stagnic colour pattern; or Endosalic Ruptic b. an albic horizon; and Plinthic Calcaric 2. no albeluvic tonguing starting within 100 cm of the soil surface. Endogleyic Sodic PLANOSOLS Mollic Alcalic Gypsic Alumic Petrocalcic Dystric Calcic Eutric Alic Gelic Acric Greyic Luvic Arenic Lixic Siltic Umbric Clayic Haplic Chromic Drainic Transportic
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Key to the Reference Soil Groups Prefix qualifiers Suffix qualifiers Other soils having Folic Thionic 1. within 50 cm of the mineral soil surface in some parts Histic Albic reducing conditions for some time during the year and in Technic Manganiferric half or more of the soil volume, single or in combination, Vertic Ferric a. a stagnic colour pattern; or Endosalic Ruptic b. an albic horizon; and Plinthic Geric 2. no albeluvic tonguing starting within 100 cm of the soil Endogleyic Calcaric surface. Mollic Ornithic STAGNOSOLS Gypsic Sodic
Petrocalcic Alcalic Calcic Alumic Alic Dystric Acric Eutric Luvic Gelic Lixic Greyic Umbric Placic Haplic Arenic Siltic Clayic Rhodic Chromic Drainic Other soils having Voronic Anthric 1. a mollic horizon; and Vermic Glossic 2. a Munsell with a moist chroma, moist, of 2 or less from Technic Tephric the soil surface to a depth of 20 cm or more, or having Leptic Sodic this chroma directly below any plough layer that is 20 cm Vertic Pachic or more deep; and Endofluvic Oxyaquic 3. a calcic horizon, or concentrations of secondary carbonates starting within 50 cm below the lower limit of Endosalic Greyic the mollic horizon and, if present, above a cemented or Gleyic Densic indurated layer; and Vitric Skeletic
4. a base saturation (by 1 M NH4OAc) of 50 percent or more Andic Arenic from the soil surface to the calcic horizon or the Stagnic Siltic concentrations of secondary carbonates throughout. Petrogypsic Clayic CHERNOZEMS Gypsic Novic Petroduric Duric Petrocalcic Calcic Luvic Haplic
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Key to the Reference Soil Groups Prefix qualifiers Suffix qualifiers Other soils having Vermic Anthric 1. a mollic horizon; and Technic Glossic 2. a calcic horizon, or concentrations of secondary Leptic Tephric carbonates starting within 50 cm below the lower limit of Vertic Sodic the mollic horizon and, if present, above a cemented or Endosalic Oxyaquic indurated layer; and Gleyic Greyic 3. a base saturation (by 1 M NH4OAc) of 50 percent or more from the soil surface to the calcic horizon or the Vitric Densic concentrations of secondary carbonates throughout. Andic Skeletic KASTANOZEMS Stagnic Arenic Petrogypsic Siltic Gypsic Clayic Petroduric Chromic Duric Novic Petrocalcic Calcic Luvic Haplic Other soils having Vermic Anthric 1. a mollic horizon; and Greyic Albic
2. a base saturation (by 1 M NH4OAc) of 50 percent or more Technic Abruptic throughout to a depth of 100 cm or more from the soil Rendzic Glossic surface or to continuous rock or a cemented or indurated Leptic Calcaric layer, whichever is shallower. Vertic Tephric PHAEOZEMS Endosalic Sodic
Gleyic Pachic Vitric Oxyaquic Andic Densic Ferralic Skeletic Stagnic Arenic Petrogypsic Siltic Petroduric Clayic Duric Chromic Petrocalcic Novic Calcic Luvic Haplic Other soils having Petric Ruptic 1. a petrogypsic horizon starting within 100 cm of the soil Hypergypsic Sodic surface; or Hypogypsic Hyperochric 2. a gypsic horizon starting within 100 cm of the soil surface Arzic Takyric and no argic horizon unless the argic horizon is Technic Yermic permeated with gypsum or calcium carbonate. Hyperskeletic Aridic GYPSISOLS Leptic Skeletic
Vertic Arenic Endosalic Siltic Endogleyic Clayic Petroduric Transportic Duric Novic Petrocalcic Calcic Luvic Haplic
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Key to the Reference Soil Groups Prefix qualifiers Suffix qualifiers Other soils having a petroduric or duric horizon starting within Petric Ruptic 100 cm of the soil surface. Fractipetric Sodic DURISOLS Technic Takyric Leptic Yermic Vertic Aridic Endogleyic Hyperochric Gypsic Arenic Petrocalcic Siltic Calcic Clayic Luvic Chromic Lixic Transportic Haplic Novic Other soils having Petric Ruptic 1. a petrocalcic horizon starting within 100 cm of the soil Hypercalcic Sodic surface; or Hypocalcic Takyric 2. a calcic horizon starting within 100 cm of the soil surface Technic Yermic 1 and no argic horizon unless the argic horizon is Hyperskeletic Aridic permeated with calcium carbonate. Leptic Hyperochric CALCISOLS Vertic Densic Endosalic Skeletic Endogleyic Arenic Gypsic Siltic Luvic Clayic Lixic Chromic Haplic Transportic Novic
1 Deleted: a calcareous matrix between 50 cm from the soil surface and the calcic horizon throughout if the calcic horizon starts below 50 cm; and
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Key to the Reference Soil Groups Prefix qualifiers Suffix qualifiers Other soils having an argic horizon starting within 100 cm of the soil Fragic Anthric surface with albeluvic tonguing at its upper boundary. Cutanic Manganiferric ALBELUVISOLS Folic Ferric Histic Abruptic Technic Ruptic Gleyic Alumic Stagnic Dystric Umbric Eutric Cambic Gelic Haplic Oxyaquic Greyic Densic Arenic Siltic Clayic Drainic Transportic Novic Other soils having Hyperalic Anthric
1. an argic horizon, which has a CEC (by 1 M NH4OAc) of Lamellic Fragic -1 1 24 cmolc kg clay or more throughout or to a depth of Cutanic Manganiferric 50 cm below its upper limit, whichever is shallower, either Albic Ferric starting within 100 cm of the soil surface, or within 200 cm of the soil surface if the argic horizon is overlain by loamy Technic Abruptic sand or coarser textures throughout; and Leptic Ruptic
2. a base saturation (by 1 M NH4OAc) of less than Vertic Alumic 50 percent in the major part between 50 and 100 cm. Fractiplinthic Humic ALISOLS Petroplinthic Hyperdystric Pisoplinthic Epieutric Plinthic Turbic Gleyic Gelic Vitric Oxyaquic Andic Greyic Nitic Profondic Stagnic Hyperochric Umbric Nudiargic Haplic Densic Skeletic Arenic Silltic Clayic Rhodic Chromic Transportic Novic
1 See Annex 1.
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Key to the Reference Soil Groups Prefix qualifiers Suffix qualifiers Other soils having Vetic Anthric
1. an argic horizon that has a CEC (by 1 M NH4OAc) of less Lamellic Albic -1 1 than 24 cmolc kg clay in some part to a maximum depth Cutanic Fragic of 50 cm below its upper limit, either starting within Technic Sombric 100 cm of the soil surface, or within 200 cm of the soil surface if the argic horizon is overlain by loamy sand or Leptic Manganiferric coarser textures throughout, and Fractiplinthic Ferric
2. a base saturation (by 1 M NH4OAc) of less than Petroplinthic Abruptic 50 percent in the major part between 50 and 100 cm. Pisoplinthic Ruptic ACRISOLS Plinthic Alumic Gleyic Humic Vitric Hyperdystric Andic Epieutric Nitic Oxyaquic Stagnic Greyic Umbric Profondic Haplic Hyperochric Nudiargic Densic Skeletic Arenic Siltic Clayic Rhodic Chromic Transportic Novic
Other soils having an argic horizon with a CEC (by 1 M NH4OAc) of Lamellic Anthric -1 2 24 cmolc kg clay or more throughout or to a depth of 50 cm below Cutanic Fragic its upper limit, whichever is shallower, either starting within 100 cm Albic Manganiferric of the soil surface or within 200 cm of the soil surface if the argic horizon is overlain by loamy sand or coarser textures throughout. Escalic Ferric LUVISOLS Technic Abruptic Leptic Ruptic Vertic Humic Gleyic Sodic Vitric Epidystric Andic Hypereutric Nitic Turbic Stagnic Gelic Calcic Oxyaquic Haplic Greyic Profondic Hyperochric Nudiargic Densic Skeletic Arenic Siltic Clayic Rhodic Chromic Transportic Novic
1 See Annex 1. 2 See Annex 1.
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Key to the Reference Soil Groups Prefix qualifiers Suffix qualifiers Other soils having an argic horizon, either starting within 100 cm of Vetic Anthric the soil surface or within 200 cm of the soil surface if the argic Lamellic Albic horizon is overlain by loamy sand or coarser textures throughout. Cutanic Fragic LIXISOLS Technic Manganiferric Leptic Ferric Gleyic Abruptic Vitric Ruptic Andic Humic Fractiplinthic Epidystric Petroplinthic Hypereutric Pisoplinthic Oxyaquic Plinthic Greyic Nitic Profondic Stagnic Hyperochric Calcic Nudiargic Haplic Densic Skeletic Arenic Siltic Clayic Rhodic Chromic Transportic Novic Other soils having an umbric or mollic horizon. Folic Anthric UMBRISOLS Histic Albic Technic Brunic Leptic Ornithic Fluvic Thionic Endogleyic Glossic Vitric Humic Andic Alumic Endogleyic Hyperdystric Ferralic Endoeutric Stagnic Pachic Mollic Turbic Cambic Gelic Haplic Oxyaquic Greyic Laxic Placic Densic Skeletic Arenic Siltic Clayic Chromic Drainic Novic
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Key to the Reference Soil Groups Prefix qualifiers Suffix qualifiers Other soils having Lamellic Ornithic 1. a weighted average texture of loamy sand or coarser, if Hypoluvic Gypsiric cumulative layers of finer texture are less than 15 cm Hyperalbic Calcaric thick, either to a depth of 100 cm from the soil surface or Albic Tephric to a petroplinthic, pisoplinthic, plinthic or salic horizon starting between 50 and 100 cm from the soil surface; and Rubic Hyposalic 2. less than 40 percent (by volume) of gravels or coarser Brunic Dystric fragments in all layers within 100 cm of the soil surface or Hydrophobic Eutric to a petroplinthic, pisoplinthic, plinthic or salic horizon Protic Petrogleyic starting between 50 and 100 cm from the soil surface; and Folic Turbic 3. no fragic, irragric, hortic, plaggic or terric horizon; and Technic Gelic 4. no layers with andic or vitric properties with a combined Endosalic Greyic thickness of 15 cm or more. Endogleyic Placic ARENOSOLS Fractiplinthic Hyperochric Petroplinthic Yermic Pisoplinthic Aridic Plinthic Transportic Ferralic Novic Endostagnic Haplic Other soils having Folic Fragic 1. a cambic horizon starting within 50 cm of the soil surface Anthraquic Manganiferric and having its base 25 cm or more below the soil surface Hortic Ferric or 15 cm or more below any plough layer; or Irragric Ornithic 2. an anthraquic, hortic, hydragric, irragric, plaggic or terric Plaggic Ruptic horizon; or Terric Colluvic 3. a fragic, petroplinthic, pisoplinthic, plinthic, salic, thionic or vertic horizon starting within 100 cm of the soil surface; Technic Gypsiric or Leptic Calcaric 4. one or more layers with andic or vitric properties with a Vertic Tephric combined thickness of 15 cm or more within 100 cm of Thionic Alumic the soil surface. Fluvic Sodic CAMBISOLS Endosalic Alcalic Endogleyic Humic Vitric Dystric Andic Eutric Endogleyic Laxic Fractiplinthic Turbic Petroplinthic Gelic Pisoplinthic Oxyaquic Plinthic Greyic Ferralic Ruptic Fragic Pisocalcic Gelistagnic Hyperochric Stagnic Takyric Haplic Yermic Aridic Densic Skeletic Siltic Clayic Rhodic Chromic Escalic Transportic Novic
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Key to the Reference Soil Groups Prefix qualifiers Suffix qualifiers Other soils. Folic Brunic REGOSOLS Aric Ornithic Colluvic Gypsiric Technic Calcaric Leptic Tephric Endogleyic Humic Thaptovitric Hyposalic Thaptandic Sodic Gelistagnic Dystric Stagnic Eutric Haplic Turbic Gelic Oxyaquic Vermic Hyperochric Takyric Yermic Aridic Densic Skeletic Arenic Siltic Clayic Escalic Transportic
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Chapter 4 Description, distribution, use and management of Reference Soil Groups
This chapter gives an overview of all the RSGs recognized in the WRB. A brief description is provided with corresponding names in other major soil classification systems, followed by the regional distribution of each group. Land use and management concludes each description. More detailed information on each RSG, including morphological, chemical and physical characteristics and genesis, is available in FAO (2001a) and a number of CD-ROMs (FAO, 2001b, 2003 and 2005). All these publications reflect the first edition of the WRB (FAO, 1998); new publications based on the current second edition are planned for the near future. ACRISOLS Acrisols are soils that have a higher clay content in the subsoil than in the topsoil as a result of pedogenetic processes (especially clay migration) leading to an argic subsoil horizon. Acrisols have in certain depths a low base saturation and low-activity clays. Many Acrisols correlate with Red Yellow Podzolic soils (e.g. Indonesia), Argissolos (Brazil), sols ferralitiques fortement ou moyennement désaturés (France), Red and Yellow Earths, and Ultisols with low-activity clays (United States of America). Summary description of Acrisols Connotation: From Latin acer, very acid. Strongly weathered acid soils with low base saturation at some depth. Parent material: On a wide variety of parent materials, most extensive from weathering of acid rocks, and notably in strongly weathered clays that are undergoing further degradation. Environment: Mostly old land surfaces with hilly or undulating topography, in regions with a wet tropical/monsoonal, subtropical or warm temperate climate. Forest is the natural vegetation type. Profile development: Pedogenetic differentiation of clay content with a lower content in the topsoil and a higher content in the subsoil; leaching of base cations owing to the humid environment and advanced degree of weathering. Regional distribution of Acrisols Acrisols are found in humid tropical, humid subtropical and warm temperate regions and are most extensive in Southeast Asia, the southern fringes of the Amazon Basin, the southeast of the United States of America, and in both East and West Africa. There are about 1 000 million ha of Acrisols worldwide. Management and use of Acrisols Preservation of the surface soil with its all-important organic matter and preventing erosion are preconditions for farming on Acrisols. Mechanical clearing of natural forest by extraction of root balls and filling of the holes with surrounding surface soil produces land that is largely sterile where Al concentrations of the former subsoil reach toxic levels. Adapted cropping systems with complete fertilization and careful management are required if sedentary farming is to be practised on Acrisols. The widely used slash-and-burn agriculture (shifting cultivation) may seem primitive but it is a well-adapted form of land use, developed over centuries of trial and error. If occupation periods are short (one or a few years only) and followed by a sufficiently long regeneration period (up to several decades), this system makes a
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good use of the limited resources of Acrisols. Agroforestry is recommended as a soil-protecting alternative to shifting cultivation to achieve higher yields without requiring expensive inputs. Low-input farming on Acrisols is not very rewarding. Undemanding, acidity-tolerant cash crops such as pineapple, cashew, tea and rubber can be grown with some success. Increasing areas of Acrisols are planted to oil-palm (e.g. in Malaysia and on Sumatra). Large areas of Acrisols are under forest, ranging from high, dense rain forest to open woodland. Most of the tree roots are concentrated in the humous surface horizon with only a few tap-roots extending down into the subsoil. In South America, Acrisols are also found under savannah. Acrisols are suitable for production of rainfed and irrigated crops only after liming and full fertilization. Rotation of annual crops with improved pasture maintains the organic matter content. ALBELUVISOLS Albeluvisols are soils that have, beginning within 1 m of the soil surface, a clay illuviation horizon with an irregular or broken upper boundary resulting in tonguing of bleached soil material into the illuviation horizon. Many Albeluvisols correlate with: Podzoluvisols (FAO); Sod-podzolic or Podzolic soils (Russian Federation); Fahlerden (Germany); and Glossaqualfs, Glossocryalfs and Glossudalfs (United States of America). Summary description of Albeluvisols Connotation: From Latin albus, white, and Latin eluere, to wash out. Parent material: Mostly unconsolidated glacial till, materials of lacustrine or fluvial origin and aeolian deposits (loess). Environment: Flat to undulating plains under coniferous forest (including boreal taiga) or mixed forest. The climate is temperate to boreal with cold winters, short and cool summers, and an average annual precipitation sum of 500–1 000 mm. Precipitation is distributed evenly over the year or, in the continental part of the Albeluvisol belt, has a peak in early summer. Profile development: A thin, dark surface horizon over an albic subsurface horizon that tongues into an underlying brown argic horizon. Temporarily reducing conditions with a stagnic colour pattern are common in boreal Albeluvisols. Regional distribution of Albeluvisols Albeluvisols cover an estimated 320 million ha in Europe, North Asia and Central Asia, with minor occurrences in North America. Albeluvisols are concentrated in two regions, each having a particular set of climate conditions: • the continental regions that had permafrost in the Pleistocene of northeast Europe, northwest Asia and southernwest Canada, which constitute by far the largest areas of Albeluvisols; • the loess and cover sand areas and old alluvial areas in moist temperate regions, such as France, central Belgium, the southeast of the Netherlands and the west of Germany. Management and use of Albeluvisols The agricultural suitability of Albeluvisols is limited because of their acidity, low nutrient levels, tillage and drainage problems and because of the climate, with its short growing season and severe frost during the long winter. The Albeluvisols of the northern taiga zone are almost exclusively under forest; small areas are used as pasture or hay fields. In the southern taiga zone, less than 10 percent of the non-forested area is used for agricultural production. Livestock farming is the main agricultural land use on Albeluvisols (dairy production and cattle rearing); arable cropping (cereals, potatoes, sugar beet and forage maize) plays a minor role. In the Russian Federation, the share of arable farming increases in southern and western directions, especially on Albeluvisols with higher base saturations in the subsoil. With careful tillage, liming and application of fertilizers, Albeluvisols can produce 25–30 tonnes of potatoes per hectare, 2–5 tonnes of winter wheat or 5–10 tonnes of dry herbage.
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ALISOLS Alisols are soils that have a higher clay content in the subsoil than in the topsoil as a result of pedogenetic processes (especially clay migration) leading to an argic subsoil horizon. Alisols have a low base saturation at certain depths and high-activity clays throughout the argic horizon. They lack the albeluvic tonguing as in Albeluvisols. They occur predominantly in humid tropical, humid subtropical and warm temperate regions. Many Alisols correlate with: Alissolos (Brazil); Ultisols with high-activity clays (United States of America); Kurosols (Australia); and Fersialsols and sols fersiallitiques très lessivés (France). Summary description of Alisols Connotation: Soils with a low base saturation at some depths; from Latin alumen, alum. Parent material: In a wide variety of parent materials. Most occurrences of Alisols reported so far are on weathering products of basic rocks and unconsolidated materials. Environment: Most common in hilly or undulating topography, in humid tropical, humid subtropical and monsoon climates. Profile development: Pedogenetic differentiation of clay contents with a lower content in the topsoil and a higher content in the subsoil, leaching of base cations owing to the humid environment without advanced weathering of high-activity clays; highly leached Alisols might have an albic eluviation horizon between the surface horizon and the argic subsurface horizon but lack the albeluvic tonguing of Albeluvisols. Regional distribution of Alisols Major occurrences of Alisols are found in Latin America (Ecuador, Nicaragua, Venezuela, Colombia, Peru and Brazil), in the West Indies (Jamaica, Martinique and Saint Lucia), in West Africa, the highlands of East Africa, Madagascar, and in Southeast Asia and northern Australia. FAO (2001a) estimates that about 100 million ha of these soils are used for agriculture in the tropics. Alisols occur also in subtropical regions; they are found in China, Japan and the southeast of the United States of America, and minor occurrences have been reported from around the Mediterranean Sea (Italy, France and Greece). They also occur in humid temperate regions. Management and use of Alisols Alisols occur predominantly on hilly or undulating topography. The generally unstable surface soil of cultivated Alisols makes them susceptible to erosion; truncated soils are quite common. Toxic levels of Al at shallow depth and poor natural soil fertility are added constraints in many Alisols. As a consequence, many Alisols allow only cultivation of shallow-rooting crops and crops suffer from drought stress in the dry season. A significant part of the Alisols is unproductive under a wide variety of crops. The use of acidity-tolerant crops or low-volume grazing is common. The productivity of Alisols in subsistence agriculture is generally low as these soils have a limited capacity to recover from chemical exhaustion. Where fully limed and fertilized, crops on Alisols may benefit from the considerable CEC and good water-holding capacity, and the Alisols may eventually grade into Luvisols. Alisols are increasingly planted to Al-tolerant estate crops such as tea and rubber but also to oil-palm and, in places, to coffee and sugar cane. ANDOSOLS Andosols accommodate the soils that develop in volcanic ejecta or glasses under almost any climate (except under hyperarid climate conditions). However, Andosols may also develop in other silicate-rich materials under acid weathering in humid and perhumid climates. Many Andosols belong to: Kuroboku (Japan); Andisols (United States of America); Andosols and Vitrisols (France); and volcanic ash soils. Summary description of Andosols Connotation: Typically black soils of volcanic landscapes; from Japanese an, black, and do, soil.
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Parent material: Volcanic glasses and ejecta (mainly ash, but also tuff, pumice, cinders and others) or other silicate-rich material. Environment: Undulating to mountainous, humid, and arctic to tropical regions with a wide range of vegetation types. Profile development: Rapid weathering of porous volcanic ejecta or glasses results in accumulation of stable organo-mineral complexes or short-range-order minerals such as allophane, imogolite and ferrihydrite. Acid weathering of other silicate-rich material in humid and perhumid climates also leads to the formation of stable organo-mineral complexes. Regional distribution of Andosols Andosols occur in volcanic regions all over the world. Important concentrations are found around the Pacific rim: on the west coast of South America, in Central America, Mexico, United States of America (the Rocky Mountains, Alaska), Japan, the Philippine Archipelago, Indonesia, Papua New Guinea, and New Zealand. They are also prominent on many islands in the Pacific: Fiji, Vanuatu, New Caledonia, Samoa and Hawaii. In Africa, major occurrences of Andosols are found along the Rift Valley, in Kenya, Rwanda and Ethiopia and in Madagascar. In Europe, Andosols occur in Italy, France, Germany and Iceland. The total Andosol area is estimated at some 110 million ha or less than 1 percent of the global land surface. More than half of this area is situated in the tropics. Andosols originating from parent materials other than volcanic ejecta or glasses occur in humid (often mountainous) regions. Management and use of Andosols Andosols have a high potential for agricultural production, but many of them are not used up to their capacity. Andosols are generally fertile soils, particularly Andosols in intermediate or basic volcanic ash and not exposed to excessive leaching. The strong phosphate fixation of Andosols (caused by active Al and Fe) is a problem. Ameliorative measures to reduce this effect include application of lime, silica, organic material, and phosphate fertilizer. Andosols are easy to cultivate and have good rootability and water storage properties. Strongly hydrated Andosols are difficult to till because of their low bearing capacity and their stickiness. Andosols are planted to a wide variety of crops including sugar cane, tobacco, sweet potato (tolerant of low phosphate levels), tea, vegetables, wheat and orchard crops. Andosols on steep slopes are perhaps best kept under forest. Paddy rice cultivation is a major land use on Andosols in lowlands with shallow groundwater. ANTHROSOLS Anthrosols comprise soils that have been modified profoundly through human activities, such as addition of organic materials or household wastes, irrigation and cultivation. The group includes soils otherwise known as: Plaggen soils, Paddy soils, Oasis soils, Terra Preta do Indio (Brazil), Agrozems (Russian Federation), Terrestrische anthropogene Böden (Germany), Anthroposols (Australia), and Anthrosols (China). Summary description of Anthrosols Connotation: Soils with prominent characteristics that result from human activities; from Greek anthropos, human being. Parent material: Virtually any soil material, modified by long-continued cultivation or addition of material. Environment: In many regions where people have been practising agriculture for a long time. Profile development: Influence of humans is normally restricted to the surface horizons; the horizon differentiation of a buried soil may still be intact at some depth. Regional distribution of Anthrosols Anthrosols are found wherever people have practised agriculture for a long time. Anthrosols with plaggic horizons are most common in northwest Europe. Together with Anthrosols with a terric horizon, they cover more than 500 000 ha.
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Anthrosols with irragric horizons are found in irrigation areas in dry regions, e.g. in Mesopotamia, near oases in desert regions and in parts of India. Anthrosols with an anthraquic horizon overlying a hydragric horizon (paddy soils) occupy vast areas in China and in parts of South and Southeast Asia (e.g. Sri Lanka, Viet Nam, Thailand and Indonesia). Anthrosols with hortic horizons are found all over the world where humans have fertilized the soil with household wastes and manure. The Terra Preta do Indio in the Amazon Region of Brazil belongs to this group. Management and use of Anthrosols Plaggic horizons have favourable physical properties (porosity, rootability and moisture availability), but many have less satisfactory chemical characteristics (acidity, and nutrient deficiencies). Rye, oats, barley, potato, and also the more demanding sugar beet and summer wheat are common crops on European Anthrosols with a plaggic horizon. Prior to the advent of chemical fertilizers, rye yields were 700–1 100 kg/ha, or 4–5 times the quantity of seed used. Today, these soils receive generous doses of fertilizers and average per-hectare yield levels for rye, barley and summer wheat are 5 000, 4 500 and 5 500 kg, respectively. Sugar beet and potato produce 40–50 tonnes/ha. Nowadays, they are increasingly used for production of silage maize and grass; per-hectare production levels of 12–13 tonnes of dry maize silage and 10– 13 tonnes of dry grass are considered normal. In places, Anthrosols with plaggic horizons are used for tree nurseries and horticulture. The good drainage and the dark colour of the surface soil (early warming in spring) make it possible to till and sow or plant early in the season. Soils with deep plaggic horizons in the Netherlands were in demand for the cultivation of tobacco until the 1950s. Anthrosols with a hortic horizon are kitchen soils. Well-known examples are situated on river terraces in south Maryland, United States of America, and along the Amazon River in Brazil. They have deep, black topsoils formed in layers of kitchen refuse (mainly oyster shells, fish bones, etc.) from early Indian habitations. Many countries possess small areas of soils that were modified by early inhabitants. Long-continued wet cultivation of rice leads to an anthraquic horizon with an underlying hydragric horizon. Puddling of wetland rice fields (involving destruction of the natural soil structure by intensive tillage when the soil is saturated with water) is done intentionally, inter alia to reduce percolation losses. Anthrosols with irragric horizons are formed as a result of prolonged sedimentation (predominantly silt) from irrigation water. A special case is found in depression areas where dryland crops are commonly planted on constructed ridges that alternate with drainage furrows. The original soil profile of the ridge areas is buried under a thick layer of added soil material. The ridge-and-furrow system is known from such different environments as the wet forests of western Europe and the coastal swamps of Southeast Asia where the ridges are planted to dryland crops and rice is grown in the shallow ditch areas. In parts of western Europe, notably in Ireland and the United Kingdom, calcareous materials (e.g. beach sands) were carted to areas with acid Arenosols, Podzols, Albeluvisols and Histosols. Eventually these modified surface layers of mineral material turned into terric horizons that give the soil much improved properties for arable cropping than the original surface soil. In Central Mexico, deep soils were constructed of organic-matter-rich lacustrine sediments, thus forming a system of artificial islands and channels (chinampas). These soils have a terric horizon and were the most productive lands of the Aztec empire; now most of these soils are affected by salinization. ARENOSOLS Arenosols comprise sandy soils, including both soils developed in residual sands after in situ weathering of usually quartz-rich sediments or rock, and soils developed in recently deposited sands such as dunes in deserts and beach lands. Corresponding soils in other classification systems include Psamments of the US Soil Taxonomy and the sols minéraux bruts and sols peu
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évolués in the French classification system of the CPCS (1967). Many Arenosols belong to Arenic Rudosols (Australia), Psammozems (Russian Federation) and Neossolos (Brazil). Summary description of Arenosols Connotation: Sandy soils; from Latin arena, sand. Parent material: Unconsolidated, in places calcareous, translocated materials of sandy texture; relatively small areas of Arenosols occur in extremely weathered siliceous rock. Environment: From arid to humid and perhumid, and from extremely cold to extremely hot; landforms vary from recent dunes, beach ridges and sandy plains to very old plateaus; the vegetation ranges from desert over scattered vegetation (mostly grassy) to light forest. Profile development: In the dry zone, there is little or no soil development. Arenosols in the perhumid tropics tend to develop thick albic eluviation horizons (with a spodic horizon below 200 m from the soil surface) whereas most Arenosols of the humid temperate zone show signs of alteration or transport of humus, Fe or clay, but too weak to be diagnostic. Regional distribution of Arenosols Arenosols are one of the most extensive RSGs in the world; including shifting sands and active dunes, they cover about 1 300 million ha, or 10 percent of the land surface. Vast expanses of deep aeolian sands are found on the Central African plateau between the equator and 30 °S. These Kalahari Sands form the largest body of sands on earth. Other areas of Arenosols occur in the Sahelian region of Africa, various parts of the Sahara, central and western Australia, the Near East, and China. Sandy coastal plains and coastal dune areas are of smaller geographic extent. Although most Arenosols occur in arid and semi-arid regions, they are typical azonal soils; they are found in the widest possible range of climates, from very arid to very humid and from cold to hot. Arenosols are widespread in aeolian landscapes but occur also in marine, littoral, and lacustrine sands and in coarse-grained weathering mantles of siliceous rocks, mainly sandstone, quartzite and granite. There is no limitation as to age or period in which soil formation took place. Arenosols occur on very old surfaces as well as in very recent landforms, and may be associated with almost any type of vegetation. Management and use of Arenosols Arenosols occur in widely different environments, and possibilities to use them for agriculture vary accordingly. The characteristic that all Arenosols have in common is their coarse texture, accounting for their generally high permeability and low water and nutrient storage capacity. On the other hand, Arenosols offer ease of cultivation, rooting and harvesting of root and tuber crops. Arenosols in arid lands, where the annual rainfall is less than 300 mm, are predominantly used for extensive (nomadic) grazing. Dry farming is possible where the annual rainfall exceeds 300 mm. Low coherence, low nutrient storage capacity and high sensitivity to erosion are serious limitations of Arenosols in the dry zone. Good yields of small grains, melons, pulses and fodder crops have been realized on irrigated Arenosols, but high percolation losses may make surface irrigation impracticable. Drip or trickle irrigation, possibly combined with careful dosage of fertilizers, may remedy the situation. Many areas with Arenosols in the Sahelian zone (annual rainfall of 300–600 mm) are transitional to the Sahara, and their soils are covered with sparse vegetation. Uncontrolled grazing and clearing for cultivation without appropriate soil conservation measures can easily make these soils unstable and revert them to shifting dunes. Arenosols in the humid and subhumid temperate zone have similar limitations as those of the dry zone, albeit that drought is a less serious constraint. In some instances, e.g. in horticulture, the low water storage of Arenosols is considered advantageous because the soils warm up early in the season. In mixed farming systems (which are much more common) with cereals, fodder crops and grassland, supplemental sprinkler irrigation is applied during dry spells. A large part of the Arenosols of the temperate zone is under forest, either production forest or natural stands in carefully managed nature reserves.
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Arenosols in the humid tropics are best left under their natural vegetation, particularly so the deeply weathered Arenosols with an albic horizon. As nutrient elements are all concentrated in the biomass and in the soil organic matter, clearing of the land will inevitably produce infertile badlands without ecological or economic value. Under forest, the land can still produce some timber (e.g. Agathis spp.) and wood for the pulp and paper industry. Permanent cultivation of annual crops would require management inputs that are usually not economically justifiable. In places, Arenosols have been planted to perennial crops such as rubber and pepper; coastal sands are widely planted to estate crops such as coconut, cashew, casuarinas and pine, especially where good quality groundwater is within reach of the root system. Root and tuber crops benefit from the ease of harvesting, notably cassava, with its tolerance of low nutrient levels. Groundnut and bambara groundnut can be found on the better soils. Arenosols and related soils with a sandy surface texture in some regions (e.g. west Australia and parts of South Africa) may be prone to develop water-repellency, typically caused by hydrophobic exudates of soil fungi that coat sand grains. Water-repellency is most intense after lengthy spells of hot, dry weather and leads to differential water infiltration. This is thought to have ecological significance in promoting plant species diversity (e.g. in Namaqualand). Wetting agents (surfactants such as calcium lignosulphonate) are sometimes used to achieve more uniform water penetration under irrigation. Dryland wheat farmers in Australia mine clay and apply it to their sandy soils with specialized machinery. The results (more uniform germination and better herbicide efficiency) can be economically attractive where a local source of clay is available. CALCISOLS Calcisols accommodate soils in which there is substantial secondary accumulation of lime. Calcisols are common in highly calcareous parent materials and widespread in arid and semi- arid environments, often associated with highly calcareous parent materials. Formerly used soil names for many Calcisols include Desert soils and Takyrs. In the US Soil Taxonomy, most of them belong to the Calcids. Summary description of Calcisols Connotation: Soils with substantial accumulation of secondary lime; from Latin calx, lime. Parent material: Mostly alluvial, colluvial and aeolian deposits of base-rich weathering material. Environment: Level to hilly land in arid and semi-arid regions. The natural vegetation is sparse and dominated by xerophytic shrubs and trees and/or ephemeral grasses. Profile development: Typical Calcisols have a pale brown surface horizon; substantial secondary accumulation of lime occurs within 100 cm of the soil surface. Regional distribution of Calcisols It is difficult to quantify the worldwide extent of Calcisols with any measure of accuracy. Many Calcisols occur together with Solonchaks that are actually salt-affected Calcisols and/or with other soils having secondary accumulation of lime that do not key out as Calcisols. The total Calcisol area may well amount to some 1 000 million ha, nearly all of it in the arid and semi- arid tropics and subtropics of both hemispheres. Land use and management Management and use of Calcisols Vast areas of so-called natural Calcisols are under shrubs, grasses and herbs and are used for extensive grazing. Drought-tolerant crops such as sunflower might be grown rainfed, preferably after one or a few fallow years, but Calcisols reach their full productive capacity only where carefully irrigated. Extensive areas of Calcisols are used for production of irrigated winter wheat, melons, and cotton in the Mediterranean zone. Sorghum bicolor (el sabeem) and fodder crops, such as Rhodes grass and alfalfa, are tolerant of high Ca levels. Some 20 vegetable crops have been grown successfully on irrigated Calcisols fertilized with nitrogen (N), phosphorus (P) and trace elements (as Fe iron and zinc [Zn]).
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Furrow irrigation is superior to basin irrigation on slaking Calcisols because it reduces surface crusting/caking and seedling mortality; pulse crops in particular are very vulnerable in the seedling stage. In places, arable farming is hindered by stoniness of the surface soil and/or a petrocalcic horizon at shallow depth. CAMBISOLS Cambisols combine soils with at least an incipient subsurface soil formation. Transformation of parent material is evident from structure formation and mostly brownish discoloration, increasing clay percentage, and/or carbonate removal. Other soil classification systems refer to many Cambisols as: Braunerden (Germany), Sols bruns (France), Brown soils/Brown Forest soils (older US systems), or Burozems (Russian Federation). FAO coined the name Cambisols, adopted by Brazil (Cambissolos); US Soil Taxonomy classifies most of these soils as Inceptisols. Summary description of Cambisols Connotation: Soils with at least the beginnings of horizon differentiation in the subsoil evident from changes in structure, colour, clay content or carbonate content; from Italian cambiare, to change. Parent material: Medium and fine-textured materials derived from a wide range of rocks. Profile development: Cambisols are characterized by slight or moderate weathering of parent material and by absence of appreciable quantities of illuviated clay, organic matter, Al and/or Fe compounds. Cambisols also encompass soils that fail one or more characteristics diagnostic for other RSGs, including highly weathered ones. Environment: Level to mountainous terrain in all climates; wide range of vegetation types. Regional distribution of Cambisols Cambisols cover an estimated 1 500 million ha worldwide. This RSG is particularly well represented in temperate and boreal regions that were under the influence of glaciations during the Pleistocene, partly because the parent material of the soil is still young, but also because soil formation is slow in cool regions. Erosion and deposition cycles explain the occurrence of Cambisols in mountain regions. Cambisols also occur in dry regions but are less common in the humid tropics and subtropics where weathering and soil formation proceed at much faster rates than in temperate, boreal and dry regions. The young alluvial plains and terraces of the Ganges– Brahmaputra system are probably the largest continuous surface of Cambisols in the tropics. Cambisols are also common in areas with active geologic erosion, where they may occur in association with mature tropical soils. Management and use of Cambisols Cambisols generally make good agricultural land and are used intensively. Cambisols with high base saturation in the temperate zone are among the most productive soils on earth. More acid Cambisols, although less fertile, are used for mixed arable farming and as grazing and forest land. Cambisols on steep slopes are best kept under forest; this is particularly true for Cambisols in highlands. Cambisols on irrigated alluvial plains in the dry zone are used intensively for production of food and oil crops. Cambisols in undulating or hilly terrain (mainly colluvial) are planted to a variety of annual and perennial crops or are used as grazing land. Cambisols in the humid tropics are typically poor in nutrients but are still richer than associated Acrisols or Ferralsols and they have a greater CEC. Cambisols with groundwater influence in alluvial plains are highly productive paddy soils. CHERNOZEMS Chernozems accommodate soils with a thick black surface layer that is rich in organic matter. The Russian soil scientist Dokuchaev coined the name Chernozem in 1883 to denote the typical zonal soil of the tall grass steppes in continental Russia. Many Chernozems correspond to: Calcareous Black Soils (older US systems);and Kalktschernoseme (Germany); Chernosols
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(France); Eluviated Black Soils (Canada); several suborders (especially Udolls) of the Mollisols (United States of America); and Chernossolos (Brazil). Summary description of Chernozems Connotation: Black soils rich in organic matter; from Russian chernij, black, and zemlja, earth or land. Parent material: Mostly aeolian and re-washed aeolian sediments (loess). Environment: Regions with a continental climate with cold winters and hot summers, which are dry at least in the late summer; in flat to undulating plains with tall-grass vegetation (forest in the northern transitional zone). Profile development: Dark brown to black mollic surface horizon, in many cases over a cambic or argic subsurface horizon; with secondary carbonates or a calcic horizon in the subsoil. Regional distribution of Chernozems Chernozems cover an estimated 230 million ha worldwide, mainly in the middle latitude steppes of Eurasia and North America, north of the zone with Kastanozems. Management and use of Chernozems Russian soil scientists rank the deep, central Chernozems among the best soils in the world. With less than half of all Chernozems in Eurasia being used for arable cropping, these soils constitute a formidable resource for the future. Preservation of the favourable soil structure through timely cultivation and careful irrigation at low watering rates prevents ablation and erosion. Application of P fertilizers is required for high yields. Wheat, barley and maize are the principal crops grown, alongside other food crops and vegetables. Part of the Chernozem area is used for livestock rearing. In the northern temperate belt, the possible growing period is short and the principal crops grown are wheat and barley, in places in rotation with vegetables. Maize is widely grown in the warm temperate belt. Maize production tends to stagnate in drier years unless the crop is irrigated adequately. CRYOSOLS Cryosols comprise mineral soils formed in a permafrost environment. Where water is present, it occurs primarily in the form of ice. Cryogenic processes are the dominant soil-forming processes. Cryosols are widely known as permafrost soils. Other common names for many Cryosols are: Gelisols (United States of America), Cryozems (Russian Federation), Cryomorphic soils and Polar desert soils. Summary description of Cryosols Connotation: Frost-affected soils; from Greek kryos, cold. Parent material: A wide variety of materials, including glacial till and aeolian, alluvial, colluvial and residual materials. Environment: Flat to mountainous areas in Antarctic, Arctic, subarctic and boreal regions affected by permafrost, notably in depressions. Cryosols are associated with sparsely to continuously vegetated tundra, open-canopy lichen coniferous forest and closed-canopy coniferous or mixed coniferous and deciduous forest. Profile development: In the presence of water, cryogenic processes produce cryoturbated horizons, frost heave, thermal cracking, ice segregation and patterned ground microrelief. Regional distribution of Cryosols Geographically, Cryosols are circumpolar in both the Northern and Southern Hemispheres. They cover an estimated 1 800 million ha km2, or about 13 percent of the global land surface. Cryosols occur in the permafrost regions of the Arctic, and are widespread in the subarctic zone, discontinuous in the boreal zone, and sporadic in more temperate mountainous regions. Major areas with Cryosols are found in the Russian Federation (1 000 million ha), Canada (250 million ha), China (190 million ha), Alaska (110 million ha), and in parts of Mongolia.
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Smaller occurrences have been reported from northern Europe, Greenland and the ice-free areas of Antarctica. Management and use of Cryosols Natural and human-induced biological activity in Cryosols is confined to the active surface layer that thaws every summer and also protects the underlying permafrost. Removal of the peat layer on top of the soil or of the vegetation and/or disturbance of the surface soil often lead to alterations of the permafrost depth and to rapid and drastic environmental changes, with possible damage to structures created by humans. Most areas of Cryosols in North America and Eurasia are in the natural state and support sufficient vegetation for grazing animals, such as caribou, reindeer and musk oxen. Large herds of caribou still migrate seasonally in the northern part of North America; reindeer herding is an important industry in the vast northern areas, especially in northern Europe. Overgrazing leads rapidly to erosion and other environmental damage. Human activities, mainly relating to agriculture, oil and gas production, and mining, have had a major impact on these soils. Severe thermokarsting has occurred on land cleared for agriculture. Improper management of pipelines and mining can cause oil spills and chemical pollution that affect large areas. DURISOLS Durisols are associated mainly with old surfaces in arid and semi-arid environments and accommodate very shallow to moderately deep, moderately well- to well-drained soils that contain cemented secondary silica (SiO2) within 100 cm of the soil surface. Many Durisols are known as: hardpan soils (Australia), dorbank (South Africa), Durids (United States of America), or as duripan phase of other soils, e.g. of Calcisols (FAO). Summary description of Durisols Connotation: Soils with hardened secondary silica; from Latin durus, hard. Parent material: Silicate-rich materials, mainly alluvial and colluvial deposits of all texture classes. Environment: Level and slightly sloping alluvial plains, terraces and gently sloping piedmont plains in arid, semi-arid and Mediterranean regions. Profile development: Strongly weathered soils with a hard layer of secondary silica (petroduric horizon) or nodules of secondary silica (duric horizon); eroded Durisols with exposed petroduric horizons are common in gently sloping terrain. Regional distribution of Durisols Extensive areas of Durisols occur in Australia, in South Africa and Namibia, and in the United States of America (notably, Nevada, California and Arizona); minor occurrences have been reported from Central and South America and from Kuwait. Durisols are a relatively new introduction in international soil classification and have not often been mapped as such. A precise indication of their extent is not yet available. Land use and management Management and use of Durisols The agricultural use of Durisols is limited to extensive grazing (rangeland). Durisols in natural environments generally support enough vegetation to contain erosion, but elsewhere erosion of the surface soil is widespread. Stable landscapes occur in dry regions where Durisols were eroded down to their resistant duripan. Durisols may be cultivated with some success where sufficient irrigation water is available. A petroduric horizon may need to be broken up or removed altogether if it forms a barrier to root and water penetration. Excess levels of soluble salts may affect Durisols in low- lying areas. Hard duripan material is widely used in road construction.
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FERRALSOLS Ferralsols represent the classical, deeply weathered, red or yellow soils of the humid tropics. These soils have diffuse horizon boundaries, a clay assemblage dominated by low-activity clays (mainly kaolinite) and a high content of sesquioxides. Local names usually refer to the colour of the soil. Many Ferralsols are known as: Oxisols (United States of America); Latossolos (Brazil); Alítico, Ferrítico and Ferralítico (Cuba); Sols ferralitiques (France); and Ferralitic soils (Russian Federation). Summary description of Ferralsols Connotation: Red and yellow tropical soils with a high content of sesquioxides; from Latin ferrum, iron, and alumen, alum. Parent material: Strongly weathered material on old, stable geomorphic surfaces; more commonly in material weathered from basic rock than from siliceous material. Environment: Typically in level to undulating land of Pleistocene age or older; less common on younger, easily weathering rocks. Perhumid or humid tropics; minor occurrences elsewhere are considered to be relics from past eras with a warmer and wetter climate than today. Profile development: Deep and intensive weathering has resulted in a residual concentration of resistant primary minerals (e.g. quartz) alongside sesquioxides and kaolinite. This mineralogy and the relatively low pH explain the stable microstructure (pseudo-sand) and yellowish (goethite) or reddish (hematite) soil colours. Regional distribution of Ferralsols The worldwide extent of Ferralsols is estimated at some 750 million ha, almost exclusively in the humid tropics on the continental shields of South America (especially Brazil) and Africa (especially Congo, Democratic Republic of the Congo, southern Central African Republic, Angola, Guinea and eastern Madagascar). Outside the continental shields, Ferralsols are restricted to regions with easily weathering basic rock and a hot and humid climate, e.g. in Southeast Asia. Management and use of Ferralsols Most Ferralsols have good physical properties. Great soil depth, good permeability and stable microstructure make Ferralsols less susceptible to erosion than most other intensely weathered tropical soils. Moist Ferralsols are friable and easy to work. They are well drained but may in times be droughty because of their low available water storage capacity. The chemical fertility of Ferralsols is poor; weatherable minerals are scarce or absent, and cation retention by the mineral soil fraction is weak. Under natural vegetation, nutrient elements that are taken up by the roots are eventually returned to the surface soil with falling leaves and other plant debris. The bulk of all cycling plant nutrients is contained in the biomass; available plant nutrients in the soil are concentrated in the soil organic matter. If the process of nutrient cycling is interrupted, e.g. upon introduction of low-input sedentary subsistence farming, the rootzone will rapidly become depleted of plant nutrients. Maintaining soil fertility by manuring, mulching and/or adequate (i.e. long enough) fallow periods or agroforestry practices, and prevention of surface soil erosion are important management requirements. Strong retention (fixing) of P is a characteristic problem of Ferralsols (and several other soils, e.g. Andosols). Ferralsols are normally also low in N, K, secondary nutrients (Ca, Mg and S), and some 20 micronutrients. Silicon deficiency is possible where silicon-demanding crops (e.g. grasses) are grown. In Mauritius, soils are tested for available silicon and fertilized with silicon amendments. Manganese and Zn zinc, which are very soluble at low pH, may at some time reach toxic levels in the soil or become deficient after intense leaching of the soil. Boron and copper deficiencies may also be encountered. Liming is a means of raising the pH value of the rooted surface soil. Liming combats Al toxicity and raises the ECEC. On the other hand, it lowers the anion exchange capacity, which might lead to collapse of structure elements and slaking at the soil surface. Therefore, frequent
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small doses of lime or basic slag are preferable to one massive application; 0.5–2 tonnes/ha of lime or dolomite are normally enough to supply Ca as a nutrient and to buffer the low soil pH of many Ferralsols. Surface application of gypsum, as a suitably mobile form of Ca, can increase the depth of crop root development (in addition, the sulphate in the gypsum reacts with sesquioxides to produce a “self-liming” effect). This relatively recent innovation is now practised widely, especially in Brazil. Fertilizer selection and the mode and timing of fertilizer application determine to a great extent the success of agriculture on Ferralsols. Slow-release phosphate (phosphate rock) applied at a rate of several tonnes per hectare eliminates P deficiency for a number of years. For a quick fix, much more soluble double or triple superphosphate is used, needed in much smaller quantities, especially if placed in the direct vicinity of the roots. The phosphate rock option is probably only viable economically where it is locally available and when other P fertilizers are not easily purchased. Sedentary subsistence farmers and shifting cultivators on Ferralsols grow a variety of annual and perennial crops. Extensive grazing is also common and considerable areas of Ferralsols are not used for agriculture at all. The good physical properties of Ferralsols and the often level topography would encourage more intensive forms of land use if problems caused by poor chemical properties could be overcome. FLUVISOLS Fluvisols accommodate genetically young, azonal soils in alluvial deposits. The name Fluvisols may be misleading in the sense that these soils are not confined only to river sediments (Latin fluvius, river); they also occur in lacustrine and marine deposits. Many Fluvisols correlate with: Alluvial soils (Russian Federation); Hydrosols (Australia); Fluvents and Fluvaquents (United States of America); Auenböden, Marschen, Strandböden, Watten and Unterwasserböden (Germany); Neossolos (Brazil); and Sols minéraux bruts d’apport alluvial ou colluvial or Sols peu évolués non climatiques d’apport alluvial ou colluvial (France). Summary description of Fluvisols Connotation: Soils developed in alluvial deposits; from Latin fluvius, river. Parent material: Predominantly recent, fluvial, lacustrine and marine deposits. Environment: Alluvial plains, river fans, valleys and tidal marshes on all continents and in all climate zones; many Fluvisols under natural conditions are flooded periodically. Profile development: Profiles with evidence of stratification; weak horizon differentiation but a distinct topsoil horizon may be present. Redoximorphic features are common, in particular in the lower part of the profile. Regional distribution of Fluvisols Fluvisols occur on all continents and in all climates. They occupy some 350 million ha worldwide, of which more than half are in the tropics. Major concentrations of Fluvisols are found: • along rivers and lakes, e.g. in the Amazon basin, the Ganges Plain of India, the plains near Lake Chad in Central Africa, and the marshlands of Brazil, Paraguay and northern Argentina; • in deltaic areas, e.g. the deltas of the Ganges–Brahmaputra, Indus, Mekong, Mississippi, Nile, Niger, Orinoco, Plate, Po, Rhine and Zambezi; • in areas of recent marine deposits, e.g. the coastal lowlands of Sumatra, Kalimantan and Irian (Indonesia and Papua New Guinea). Major areas of Fluvisols with a thionic horizon or sulphidic material (Acid Sulphate Soils) are found in the coastal lowlands of Southeast Asia (Indonesia, Viet Nam and Thailand), West Africa (Senegal, Gambia, Guinea Bissau, Sierra Leone and Liberia) and along the northeast coast of South America (French Guiana, Guyana, Suriname and Venezuela).
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Management and use of Fluvisols The good natural fertility of most Fluvisols and attractive dwelling sites on river levees and on higher parts in marine landscapes were recognized in prehistoric times. Later, great civilizations developed in river landscapes and on marine plains. Paddy rice cultivation is widespread on tropical Fluvisols with satisfactory irrigation and drainage. Paddy land should be dry for at least a few weeks every year in order to prevent the redox potential of the soil from becoming so low that nutritional problems (Fe or H2S) arise. A dry period also stimulates microbial activity and promotes mineralization of organic matter. Many dryland crops are grown on Fluvisols as well, normally with some form of water control. Tidal lands that are strongly saline are best kept under mangroves or some other salt-tolerant vegetation. Such areas are ecologically valuable and can, with caution, be used for fishing, hunting, salt pans or woodcutting for charcoal or fuelwood. Fluvisols with a thionic horizon or sulphidic material suffer from severe acidity and high levels of Al toxicity. GLEYSOLS Gleysols are wetland soils that, unless drained, are saturated with groundwater for long enough periods to develop a characteristic gleyic colour pattern. This pattern is essentially made up of reddish, brownish or yellowish colours at ped surfaces and/or in the upper soil layer or layers, in combination with greyish/bluish colours inside the peds and/or deeper in the soil. Common names for many Gleysols are: gley and meadow soils (former Soviet Union); Gleyzems (Russian Federation); Gleye (Germany); Gleissolos (Brazil); and groundwater soils. Many of the WRB Gleysols correlate with the aquic suborders of the US Soil Taxonomy (Aqualfs, Aquents, Aquepts, Aquolls, etc). Summary description of Gleysols Connotation: Soils with clear signs of groundwater influence; from Russian gley, mucky mass. Parent material: A wide range of unconsolidated materials, mainly fluvial, marine and lacustrine sediments of Pleistocene or Holocene age, with basic to acidic mineralogy. Environment: Depression areas and low landscape positions with shallow groundwater. Profile development: Evidence of reduction processes with segregation of Fe compounds within 50 cm of the soil surface. Regional distribution of Gleysols Gleysols occupy an estimated 720 million ha worldwide. They are azonal soils and occur in nearly all climates, from perhumid to arid. The largest extent of Gleysols is in subarctic areas in the north of the Russian Federation (especially Siberia), Canada and Alaska, and in humid temperate and subtropical lowlands, e.g. in China and Bangladesh. An estimated 200 million ha of Gleysols are found in the tropics, mainly in the Amazon region, equatorial Africa, and the coastal swamps of Southeast Asia. Management and use of Gleysols The main obstacle to utilization of Gleysols is the necessity to install a drainage system to lower the groundwater table. Adequately drained Gleysols can be used for arable cropping, dairy farming and horticulture. Soil structure will be destroyed for a long time if soils are cultivated when too wet. Therefore, Gleysols in depression areas with unsatisfactory possibilities to lower the groundwater table are best kept under a permanent grass cover or swamp forest. Liming of drained Gleysols that are high in organic matter and/or of low pH value creates a better habitat for micro- and meso-organisms and enhances the rate of decomposition of soil organic matter (and the supply of plant nutrients). Gleysols can be put under tree crops only after the water table has been lowered with deep drainage ditches. Alternatively, the trees are planted on ridges that alternate with shallow depressions in which rice is grown. This sorjan system is applied widely in tidal swamp areas with pyritic sediments in Southeast Asia. Gleysols can be well used for wetland rice cultivation
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where the climate is appropriate. Gleysols with a thionic horizon or sulphidic material suffer from severe acidity and high levels of Al toxicity. GYPSISOLS Gypsisols are soils with substantial secondary accumulation of gypsum (CaSO4.2H2O). These soils are found in the driest parts of the arid climate zone, which explains why leading soil classification systems labelled many of them Desert soils (former Soviet Union), and Yermosols or Xerosols (FAO–UNESCO, 1971–1981). The US Soil Taxonomy terms most of them Gypsids. Summary description of Gypsisols Connotation: Soils with substantial accumulation of secondary calcium sulphate; from Greek gypsos, gypsum. Parent material: Mostly unconsolidated alluvial, colluvial or aeolian deposits of base-rich weathering material. Environment: Predominantly level to hilly land and depression areas (e.g. former inland lakes) in regions with an arid climate. The natural vegetation is sparse and dominated by xerophytic shrubs and trees and/or ephemeral grasses. Profile development: Light-coloured surface horizon; accumulation of calcium sulphate, with or without carbonates, is concentrated in the subsoil. Regional distribution of Gypsisols Gypsisols are exclusive to arid regions; their worldwide extent is probably of the order of 100 million ha. Major occurrences are in and around Mesopotamia, in desert areas in the Near East and adjacent Central Asian republics, in the Libyan and Namib deserts, in southeast and central Australia and in the southwest of the United States of America. Management and use of Gypsisols Gypsisols that contain only a low percentage of gypsum in the upper 30 cm can be used for the production of small grains, cotton, alfalfa, etc. Dry farming on deep Gypsisols makes use of fallow years and other water harvesting techniques but is rarely very rewarding because of the adverse climate conditions. Gypsisols in young alluvial and colluvial deposits have a relatively low gypsum content. Where such soils are in the vicinity of water resources, they can be very productive; many irrigation projects are established on such soils. However, even soils containing 25 percent powdery gypsum or more could still produce excellent yields of alfalfa hay (10 tonnes/ha), wheat, apricots, dates, maize and grapes if irrigated at high rates in combination with forced drainage. Irrigated agriculture on Gypsisols is plagued by rapid dissolution of soil gypsum, resulting in irregular subsidence of the land surface, caving in canal walls, and corrosion of concrete structures. Large areas with Gypsisols are in use for extensive grazing. HISTOSOLS Histosols comprise soils formed in organic material. These vary from soils developed in predominantly moss peat in boreal, arctic and subarctic regions, via moss peat, reeds/sedge peat (fen) and forest peat in temperate regions to mangrove peat and swamp forest peat in the humid tropics. Histosols are found at all altitudes, but the vast majority occurs in lowlands. Common names are peat soils, muck soils, bog soils and organic soils. Many Histosols belong to: Moore, Felshumusböden and Skeletthumusböden (Germany); Organosols (Australia); Organossolos (Brazil); Organic order (Canada); and Histosols and Histels (United States of America). Summary description of Histosols Connotation: Peat and muck soils; from Greek histos, tissue. Parent material: Incompletely decomposed plant remains, with or without admixtures of sand, silt or clay.
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Environment: Histosols occur extensively in boreal, arctic and subarctic regions. Elsewhere, they are confined to poorly drained basins and depressions, swamp and marshlands with shallow groundwater, and highland areas with a high precipitation–evapotranspiration ratio. Profile development: Mineralization is slow and transformation of plant remains through biochemical disintegration, and formation of humic substances creates a surface layer of mould with or without prolonged water saturation. Translocated organic material may accumulate in deeper tiers but is more often leached from the soil. Regional distribution of Histosols The total extent of Histosols in the world is estimated at some 325–375 million ha, the majority located in the boreal, subarctic and low arctic regions of the Northern Hemisphere. Most of the remaining Histosols occur in temperate lowlands and cool montane areas; only one-tenth of all Histosols are found in the tropics. Extensive areas of Histosols occur in the United States of America and Canada, western Europe and northern Scandinavia, and in northern regions east of the Ural mountain range. Some 20 million ha of tropical forest peat border the Sunda shelf in Southeast Asia. Smaller areas of tropical Histosols are found in river deltas, e.g. in the Orinoco Delta and the delta of the River Mekong, and in depression areas at some altitude. Management and use of Histosols The properties of the organic material (botanical composition, stratification, degree of decomposition, packing density, wood content, mineral admixtures, etc.) and the type of peat bog (basin peat [fen], raised bog, etc.) determine the management requirements and use possibilities of Histosols. Histosols without prolonged water saturation are often formed in cold environments unattractive for agricultural use. Natural peats need to be drained and, normally, also limed and fertilized in order to permit cultivation of normal crops. Centrally guided reclamation projects are almost exclusive to the temperate zone, where millions of hectares have been opened. In many instances, this has initiated the gradual degradation, and ultimately the loss, of the precious peat. In the tropics, increasing numbers of landless farmers venture onto the peat lands, where they clear the forest and cause raging peat fires in the process. Many of them abandon their land again after only a few years; the few that succeed are on shallow, topogenous peat. In recent decades, increasing areas of tropical peat land have been planted to oil-palm and pulp wood tree species such as Acacia mangium, Acacia crassicarpa and Eucalyptus spp. This practice may be less than ideal but it is far less destructive than arable subsistence farming. Another common problem encountered when Histosols are drained is the oxidation of sulphidic minerals, which accumulate under anaerobic conditions, especially in coastal regions. The sulphuric acid produced effectively destroys productivity unless lime is applied copiously, making the cost of reclamation prohibitive. In summary, it is desirable to protect and conserve fragile peat lands because of their intrinsic value (especially their common function as sponges in regulating stream flow and in supporting wetlands containing unique species of animals) and because prospects for their sustained agricultural use are meagre. Where their use is imperative, sensible forms of forestry or plantation cropping are to be preferred over annual cropping, horticulture or, the worst option, harvesting of the peat material for power generation or production of horticultural growth substrate, active carbon, flower pots, etc. Peat that is used for arable crop production will mineralize at sharply increased rates because it must be drained, limed and fertilized in order to ensure satisfactory crop growth. Under these circumstances, the drain depth should be kept as shallow as possible and prudence exercised when applying lime and fertilizers. KASTANOZEMS Kastanozems accommodate dry grassland soils, among them the zonal soils of the short-grass steppe belt, south of the Eurasian tall-grass steppe belt with Chernozems. Kastanozems have a similar profile to that of Chernozems but the humus-rich surface horizon is thinner and not as dark as that of the Chernozems and they show more prominent accumulation of secondary carbonates. The chestnut-brown colour of the surface soil is reflected in the name Kastanozem;
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common names for many Kastanozems are: (Dark) Chestnut Soils (Russian Federation), Kalktschernoseme (Germany), (Dark) Brown Soils (Canada), and Ustolls and Xerolls (United States of America). Summary description of Kastanozems Connotation: Dark brown soils rich in organic matter; from Latin castanea and Russian kashtan, chestnut, and zemlja, earth or land. Parent material: A wide range of unconsolidated materials; a large part of all Kastanozems has developed in loess. Environment: Dry and continental with relatively cold winters and hot summers; flat to undulating grasslands dominated by ephemeral short grasses. Profile development: A brown mollic horizon of medium depth, in many cases over a brown to cinnamon cambic or argic horizon; with secondary carbonates or a calcic horizon in the subsoil, in some cases also with secondary gypsum. Regional distribution of Kastanozems The total extent of Kastanozems is estimated to be about 465 million ha. Major areas are in the Eurasian short-grass steppe belt (southern Ukraine, the south of the Russian Federation, Kazakhstan and Mongolia), in the Great Plains of the United States of America, Canada and Mexico, and in the pampas and chaco regions of northern Argentina, Paraguay and southern Bolivia. Management and use of Kastanozems Kastanozems are potentially rich soils; periodic lack of soil moisture is the main obstacle to high yields. Irrigation is nearly always necessary for high yields; care must be taken to avoid secondary salinization of the surface soil. Phosphate fertilizers might be necessary for good yields. Small grains and irrigated food and vegetable crops are the principal crops grown. Wind and water erosion is a problem on Kastanozems, especially on fallow lands. Extensive grazing is another important land use on Kastanozems. However, the sparsely vegetated grazing lands are inferior to the tall-grass steppes on Chernozems, and overgrazing is a serious problem. LEPTOSOLS Leptosols are very shallow soils over continuous rock and soils that are extremely gravelly and/or stony. Leptosols are azonal soils and particularly common in mountainous regions. Leptosols include the: Lithosols of the Soil Map of the World (FAO–UNESCO, 1971–1981); Lithic subgroups of the Entisol order (United States of America); Leptic Rudosols and Tenosols (Australia); and Petrozems and Litozems (Russian Federation). In many national systems, Leptosols on calcareous rocks belong to Rendzinas, and those on other rocks to Rankers. Continuous rock at the surface is considered non-soil in many soil classification systems. Summary description of Leptosols Connotation: Shallow soils; from Greek leptos, thin. Parent material: Various kinds of continuous rock or of unconsolidated materials with less than 20 percent (by volume) fine earth. Environment: Mostly land at high or medium altitude and with strongly dissected topography. Leptosols are found in all climate zones (many of them in hot or cold dry regions), in particular in strongly eroding areas. Profile development: Leptosols have continuous rock at or very close to the surface or are extremely gravelly. Leptosols in calcareous weathering material may have a mollic horizon. Regional distribution of Leptosols Leptosols are the most extensive RSG on earth, extending over about 1 655 million ha. Leptosols are found from the tropics to the cold polar tundra and from sea level to the highest mountains. Leptosols are particularly widespread in montane areas, notably in Asia and South
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America, in the Sahara and the Arabian deserts, the Ungava Peninsula of northern Canada and in the Alaskan mountains. Elsewhere, Leptosols can be found on rocks that are resistant to weathering or where erosion has kept pace with soil formation, or has removed the top of the soil profile. Leptosols with continuous rock at less than 10 cm depth in montane regions are the most extensive Leptosols. Management and use of Leptosols Leptosols have a resource potential for wet-season grazing and as forest land. Leptosols to which the Rendzic qualifier applies are planted to teak and mahogany in Southeast Asia; those in the temperate zone are under mainly deciduous mixed forest whereas acid Leptosols are commonly under coniferous forest. Erosion is the greatest threat to Leptosol areas, particularly in montane regions in the temperate zones where high population pressure (tourism), overexploitation and increasing environmental pollution lead to deterioration of forests and threaten large areas of vulnerable Leptosols. Leptosols on hill slopes are generally more fertile than their counterparts on more level land. One or a few good crops could perhaps be grown on such slopes but at the price of severe erosion. Steep slopes with shallow and stony soils can be transformed into cultivable land through terracing, the removal of stones by hand and their use as terrace fronts. Agroforestry (a combination of or rotation of arable crops and forest trees under strict control) holds promise but is still largely in an experimental stage. The excessive internal drainage and the shallowness of many Leptosols can cause drought even in a humid environment. LIXISOLS Lixisols comprise soils that have a higher clay content in the subsoil than in the topsoil as a result of pedogenetic processes (especially clay migration) leading to an argic subsoil horizon. Lixisols have a high base saturation and low-activity clays at certain depths. Many Lixisols are included in: Red Yellow Podzolic soils (e.g. Indonesia); Argissolos (Brazil); sols ferralitiques faiblement desaturés appauvris (France); and Red and Yellow Earths, Latosols or Alfisols with low-activity clays (United States of America). Summary description of Lixisols Connotation: Soils with a pedogenetic clay differentiation (especially clay migration) between a topsoil with a lower and a subsoil with a higher clay content, low-activity clays and a high base saturation at some depths; from Latin lixivia, washed-out substances. Parent material: In a wide variety of parent materials, notably in unconsolidated, chemically strongly weathered and strongly leached, finely textured materials. Environment: Regions with a tropical, subtropical or warm temperate climate with a pronounced dry season, notably on old erosion or deposition surfaces. Many Lixisols are surmised to be polygenetic soils with characteristics formed under a more humid climate in the past. Profile development: Pedogenetic differentiation of clay content with a lower content in the topsoil and a higher content in the subsoil; weathering advanced without a marked leaching of base cations. Regional distribution of Lixisols Lixisols are found in seasonally dry tropical, subtropical and warm temperate regions on Pleistocene and older surfaces. These soils cover a total area of about 435 million ha, of which more than half occur in sub-Sahelian and East Africa, about one-quarter in South and Central America, and the remainder on the Indian subcontinent and in Southeast Asia and Australia. Management and use of Lixisols Areas with Lixisols that are still under natural savannah or open woodland vegetation are widely used for low volume grazing. Preservation of the surface soil with its all-important organic matter is of utmost importance. Degraded surface soils have low aggregate stability and are prone to slaking and/or erosion where exposed to the direct impact of raindrops. Tillage of wet soil or use of excessively heavy machinery compacts the soil and causes serious structure
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deterioration. Tillage and erosion control measures such as terracing, contour ploughing, mulching and use of cover crops help to conserve the soil. The low absolute level of plant nutrients and the low cation retention by Lixisols makes recurrent inputs of fertilizers and/or lime a precondition for continuous cultivation. Chemically and/or physically deteriorated Lixisols regenerate very slowly where not reclaimed actively. Perennial crops are to be preferred to annual crops, particularly on sloping land. Cultivation of tuber crops (cassava and sweet potato) or groundnut increases the danger of soil deterioration and erosion. Rotation of annual crops with improved pasture has been recommended in order to maintain or improve the content of soil organic matter. LUVISOLS Luvisols are soils that have a higher clay content in the subsoil than in the topsoil as a result of pedogenetic processes (especially clay migration) leading to an argic subsoil horizon. Luvisols have high-activity clays throughout the argic horizon and a high base saturation at certain depths. Many Luvisols are or were known as: Textural-metamorphic soils (Russian Federation), sols lessivés (France), Parabraunerden (Germany), Chromosols (Australia), Luvissolos (Brazil), Grey-Brown Podzolic soils (earlier terminology of the United States of America), and Alfisols with high-activity clays (US Soil Taxonomy). Summary description of Luvisols Connotation: Soils with a pedogenetic clay differentiation (especially clay migration) between a topsoil with a lower and a subsoil with a higher clay content, high-activity clays and a high base saturation at some depth; from Latin luere, to wash. Parent material: A wide variety of unconsolidated materials including glacial till, and aeolian, alluvial and colluvial deposits. Environment: Most common in flat or gently sloping land in cool temperate regions and in warm regions (e.g. Mediterranean) with distinct dry and wet seasons. Profile development: Pedogenetic differentiation of clay content with a lower content in the topsoil and a higher content in the subsoil without marked leaching of base cations or advanced weathering of high-activity clays; highly leached Luvisols might have an albic eluviation horizon between the surface horizon and an argic subsurface horizon, but lack the albeluvic tonguing of Albeluvisols. Regional distribution of Luvisols Luvisols extend over 500–600 million ha worldwide, mainly in temperate regions such as in the west and centre of the Russian Federation, the United States of America, and Central Europe, but also in the Mediterranean region and southern Australia. In subtropical and tropical regions, Luvisols occur mainly on young land surfaces. Management and use of Luvisols Most Luvisols are fertile soils and suitable for a wide range of agricultural uses. Luvisols with a high silt content are susceptible to structure deterioration where tilled when wet or with heavy machinery. Luvisols on steep slopes require erosion control measures. The eluvial horizons of some Luvisols are depleted to the extent that an unfavourable platy structure is formed. In places, the dense subsoil causes temporarily reducing conditions with a stagnic colour pattern. These are the reasons why truncated Luvisols are in many instances better soils for farming than the original, non-eroded soils. Luvisols in the temperate zone are widely grown to small grains, sugar beet and fodder; in sloping areas, they are used for orchards, forests and/or grazing. In the Mediterranean region, where Luvisols (many with the Chromic, Calcic or Vertic qualifier) are common in colluvial deposits of limestone weathering, the lower slopes are widely sown to wheat and/or sugar beet while the often eroded upper slopes are used for extensive grazing or planted to tree crops.
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NITISOLS Nitisols are deep, well-drained, red, tropical soils with diffuse horizon boundaries and a subsurface horizon with more than at least 30 percent clay and moderate to strong angular blocky structure elements that easily fall apart into characteristic shiny, flat-edged or nut-shaped polyhedric (nutty) elements. Weathering is relatively advanced but Nitisols are far more productive than most other red, tropical soils. Many Nitisols correlate with: Nitossolos (Brazil); kandic Great Groups of Alfisols and Ultisols, and different Great Groups of Inceptisols and Oxisols (United States of America); Sols Fersialitiques or Ferrisols (France); and Red Earths. Summary description of Nitisols Connotation: Deep, well-drained, red, tropical soils with a clayey nitic subsurface horizon that has typical nutty, polyhedric, blocky flat-edged or nut-shaped structure elements with shiny ped faces; from Latin nitidus, shiny. Parent material: Finely textured weathering products of intermediate to basic parent rock, in some regions rejuvenated by recent admixtures of volcanic ash. Environment: Nitisols are predominantly found in level to hilly land under tropical rain forest or savannah vegetation. Profile development: Red or reddish-brown clayey soils with a nitic subsurface horizon of high aggregate stability. The clay assemblage of Nitisols is dominated by kaolinite/(meta)halloysite. Nitisols are rich in Fe and have little water-dispersible clay. Regional distribution of Nitisols There are about 200 million ha of Nitisols worldwide. More than half of all Nitisols are found in tropical Africa, notably in the highlands (> 1 000 m) of Ethiopia, Kenya, Congo and Cameroon. Elsewhere, Nitisols are well represented at lower altitudes, e.g. in tropical Asia, South America, Central America, Southeast Africa and Australia. Management and use of Nitisols Nitisols are among the most productive soils of the humid tropics. The deep and porous solum and the stable soil structure of Nitisols permit deep rooting and make these soils quite resistant to erosion. The good workability of Nitisols, their good internal drainage and fair water holding properties are complemented by chemical (fertility) properties that compare favourably with those of most other tropical soils. Nitisols have relatively high contents of weathering minerals, and surface soils may contain several percent of organic matter, in particular under forest or tree crops. Nitisols are planted to plantation crops such as cocoa, coffee, rubber and pineapple, and are also widely used for food crop production on smallholdings. High P sorption calls for application of P fertilizers, usually provided as slow-release, low-grade phosphate rock (several tonnes per hectare, with maintenance doses every few years) in combination with smaller applications of better soluble superphosphate for short-term response by the crop. PHAEOZEMS Phaeozems accommodate soils of relatively wet grassland and forest regions in moderately continental climates. Phaeozems are much like Chernozems and Kastanozems but are leached more intensively. Consequently, they have dark, humus-rich surface horizons that, in comparison with Chernozems and Kastanozems, are less rich in bases. Phaeozems may or may not have secondary carbonates but have a high base saturation in the upper metre of the soil. Commonly used names for many Phaeozems are: Brunizems (Argentina and France); Dark grey forest soils and Leached and podzolized chernozems (former Soviet Union); Tschernoseme (Germany); Dusky-red prairie soils (older classification of the United States of America); Udolls and Albolls (US Soil Taxonomy); and Phaeozems (including most of the former Greyzems) (FAO). Summary description of Phaeozems Connotation: Dark soils rich in organic matter; from Greek phaios, dusky, and Russian zemlja, earth or land.
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Parent material: Aeolian (loess), glacial till and other unconsolidated, predominantly basic materials. Environment: Warm to cool (e.g. tropical highlands) moderately continental regions, humid enough that there is, in most years, some percolation through the soil, but also with periods in which the soil dries out; flat to undulating land; the natural vegetation is grassland such as tall- grass steppe and/or forest. Profile development: A mollic horizon (thinner and in many soils less dark than in Chernozems), mostly over a cambic or argic subsurface horizon. Regional distribution of Phaeozems Phaeozems cover an estimated 190 million ha worldwide. Some 70 million ha of Phaeozems are found in the humid and subhumid Central Lowlands and easternmost parts of the Great Plains of the United States of America. Another 50 million ha of Phaeozems are in the subtropical pampas of Argentina and Uruguay. The third largest area of Phaeozems (18 million ha) is in northeast China, followed by extensive areas in the centre of the Russian Federation. Smaller, mostly discontinuous areas are found in Central Europe, notably the Danube area of Hungary and adjacent countries and in montane areas in the tropics. Management and use of Phaeozems Phaeozems are porous, fertile soils and make excellent farmland. In the United States of America and Argentina, Phaeozems are in use for the production of soybean and wheat (and other small grains). Phaeozems on the high plains of Texas produce good yields of irrigated cotton. Phaeozems in the temperate belt are planted to wheat, barley and vegetables alongside other crops. Wind and water erosion are serious hazards. Vast areas of Phaeozems are used for cattle rearing and fattening on improved pastures. PLANOSOLS Planosols are soils with a light-coloured, surface horizon that shows signs of periodic water stagnation and abruptly overlies a dense, slowly permeable subsoil with significantly more clay than the surface horizon. The US Soil Classification coined the name Planosols in 1938; its successor, the US Soil Taxonomy, includes most of the original Planosols in the Great Groups of the Albaqualfs, Albaquults and Argialbolls. The name has been adopted in Brazil (Planossolos). Summary description of Planosols Connotation: Soils with a coarse-textured surface horizon abruptly over a dense and finer textured subsoil, typically in seasonally waterlogged flat lands; from Latin planus, flat. Parent material: Mostly clayey alluvial and colluvial deposits. Environment: Seasonally or periodically wet, level (plateau) areas, mainly in subtropical and temperate, semi-arid and subhumid regions with light forest or grass vegetation. Profile development: Geological stratification or pedogenesis (destruction and/or removal of clay), or both, has produced relatively coarse-textured, light-coloured surface soil abruptly overlying finer textured subsoil; impeded downward percolation of water causes temporarily reducing conditions with a stagnic colour pattern, at least close to the abrupt textural change. Regional distribution of Planosols The world’s major Planosol areas occur in subtropical and temperate regions with clear alternation of wet and dry seasons, e.g. in Latin America (southern Brazil, Paraguay and Argentina), Africa (Sahelian zone, East and Southern Africa), the east of the United States of America, Southeast Asia (Bangladesh and Thailand), and Australia. Their total extent is estimated at some 130 million ha. Management and use of Planosols Natural Planosol areas support a sparse grass vegetation, often with scattered shrubs and trees that have shallow root systems and can cope with temporary waterlogging. Land use on
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Planosols is normally less intensive than that on most other soils under the same climate conditions. Vast areas of Planosols are used for extensive grazing. Wood production on Planosols is much lower than on other soils under the same conditions. Planosols in the temperate zone are mainly in grass or they are planted to arable crops such as wheat and sugar beet. Yields are modest even on drained and deeply loosened soils. Root development on natural unmodified Planosols is hindered severely by oxygen deficiency in wet periods, dense subsoil and, in places, by toxic levels of Al in the rootzone. The low hydraulic conductivity of the dense subsurface soil makes narrow drain spacing necessary. Surface modification such as ridge and furrow can lessen crop yield losses from waterlogging. Planosols in Southeast Asia are widely planted to a single crop of paddy rice, produced on bunded fields that are inundated in the rainy season. Efforts to produce dryland crops on the same land during the dry season have met with little success; the soils seem better suited to a second crop of rice with supplemental irrigation. Fertilizers are needed for good yields. Paddy fields should be allowed to dry out at least once a year in order to prevent or minimize microelement deficiencies or toxicity associated with prolonged soil reduction. Some Planosols require application of more than just NPK fertilizers, and their low fertility level may prove difficult to correct. Where temperature permits paddy rice cultivation, this is probably superior to any other kind of land use. Grasslands with supplemental irrigation in the dry season are a good land use in climates with long dry periods and short infrequent wet spells. Strongly developed Planosols with a very silty or sandy surface soil are perhaps best left untouched. PLINTHOSOLS Plinthosols are soils with plinthite, petroplinthite or pisoliths. Plinthite is an Fe-rich (in some cases also Mn-rich), humus-poor mixture of kaolinitic clay (and other products of strong weathering such as gibbsite) with quartz and other constituents that changes irreversibly to a layer with hard nodules, a hardpan or irregular aggregates on exposure to repeated wetting and drying. Petroplinthite is a continuous, fractured or broken sheet of connected, strongly cemented to indurated nodules or mottles. Pisoliths are discrete strongly cemented to indurated nodules. Both petroplinthite and pisoliths develop from plinthite by hardening. Many of these soils are known as: Groundwater Laterite Soils, Perched Water Laterite Soils and Plintossolos (Brazil); Sols gris latéritiques (France); and Plinthaquox, Plinthaqualfs, Plinthoxeralfs, Plinthustalfs, Plinthaquults, Plinthohumults, Plinthudults and Plinthustults (United States of America). Summary description of Plinthosols Connotation: Soils with plinthite, petroplinthite or pisoliths; from Greek plinthos, brick. Parent material: Plinthite is more common in weathering material from basic rock than in acidic rock weathering. In any case, it is crucial that sufficient Fe be present, originating either from the parent material itself or brought in by seepage water or ascending groundwater from elsewhere. Environment: Formation of plinthite is associated with level to gently sloping areas with fluctuating groundwater or stagnating surface water. A widely held view is that plinthite is associated with rain forest areas whereas petroplinthic and pisolithic soils are more common in the savannah zone. Profile development: Strong weathering with subsequent segregation of plinthite at the depth of groundwater fluctuation or impeded surface water drainage. Hardening of plinthite to pisoliths or petroplinthite takes place upon repeated drying and wetting. This may occur during the intervals of recession of a seasonally fluctuating water table or after geological uplift of the terrain, topsoil erosion, lowering of the groundwater level, increasing drainage capacity, and/or climate change towards drier conditions. Petroplinthite may break up into irregular aggregates or gravels, which may be transported to form colluvial or alluvial deposits. Hardening or induration requires a certain minimum concentration of iron oxides.
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Regional distribution of Plinthosols The global extent of Plinthosols is estimated at some 60 million ha. Soft plinthite is most common in the wet tropics, notably in the eastern Amazon basin, the central Congo basin and parts of Southeast Asia. Extensive areas with pisoliths and petroplinthite occur in the Sudano- Sahelian zone, where petroplinthite forms hard caps on top of uplifted/exposed landscape elements. Similar soils occur in the Southern African savannah, on the Indian subcontinent, and in drier parts of Southeast Asia and northern Australia. Management and use of Plinthosols Plinthosols present considerable management problems. Poor natural soil fertility caused by strong weathering, waterlogging in bottomlands and drought on Plinthosols with petroplinthite, pisoliths or gravels are serious limitations. Many Plinthosols outside of the wet tropics have shallow, continuous petroplinthite, which limits the rooting volume to the extent that arable farming is not possible; such land can at best be used for low-volume grazing. Soils with high contents of pisoliths (up to 80 percent) are still planted to food crops and tree crops (e.g. cocoa in West Africa, and cashew in India) but the crops suffer from drought in the dry season. Many soil and water conservation techniques are used to improve these soils for urban and peri-urban agriculture in West Africa. Civil engineers have a different appreciation of petroplinthite and plinthite than do agronomists. To them, plinthite is a valuable material for making bricks, and massive petroplinthite is a stable surface for building or it can be cut to building blocks. Gravels of broken petroplinthite can be used in foundations and as surfacing material on roads and airfields. In some instances, petroplinthite is a valuable ore of Fe, Al, Mn and/or Ti. PODZOLS Podzols are soils with a typically ash-grey upper subsurface horizon, bleached by loss of organic matter and iron oxides, on top of a dark accumulation horizon with brown, reddish or black illuviated humus and/or reddish Fe compounds. Podzols occur in humid areas in the boreal and temperate zones and locally also in the tropics. The name Podzol is used in most national soil classification systems; other names for many of these soils are: Spodosols (China and United States of America), Espodossolos (Brazil), and Podosols (Australia). Summary description of Podzols Connotation: Soils with a spodic illuviation horizon under a subsurface horizon that has the appearance of ash and is covered by an organic layer; from Russian pod, underneath, and zola, ash. Parent material: Weathering materials of siliceous rock, including glacial till and alluvial and aeolian deposits of quartzite sands. Podzols in the boreal zone occur on almost any rock. Environment: Mainly in humid temperate and boreal regions of the Northern Hemisphere, in level to hilly land under heather and/or coniferous forest; in the humid tropics under light forest. Profile development: Complexes of Al, Fe and organic compounds migrate from the surface soil downwards with percolating rainwater. The metal–humus complexes precipitate in an illuvial spodic horizon; the overlying eluvial horizon remains bleached and is in many Podzols an albic horizon. This is covered by an organic layer whereas dark mineral topsoil horizons are absent in most boreal Podzols. Regional distribution of Podzols Podzols cover an estimated 485 million ha worldwide, mainly in the temperate and boreal regions of the Northern Hemisphere. They are extensive in Scandinavia, the northwest of the Russian Federation, and Canada. Besides these zonal Podzols, there are smaller occurrences of intrazonal Podzols in both the temperate zone and the tropics. Tropical Podzols occur on less than 10 million ha, mainly in residual sandstone weathering in perhumid regions and in alluvial quartz sands, e.g. in uplifted coastal areas. The exact distribution of tropical Podzols is not known; important occurrences are found along the Rio
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Negro and in French Guiana, Guyana and Suriname in South America, in the Malaysian region (Kalimantan, Sumatra and Irian), and in northern and southern Australia. They seem to be less common in Africa. Management and use of Podzols Zonal Podzols occur in regions with unattractive climate conditions for most arable land uses. Intrazonal Podzols are more frequently reclaimed for arable use than are zonal Podzols, particularly those in temperate climates. The low nutrient status, low level of available moisture and low pH make Podzols unattractive soils for arable farming. Aluminium toxicity and P deficiency are common problems. Deep ploughing (to improve the moisture storage capacity of the soil and/or to eliminate a dense illuviation horizon or hardpan), liming and fertilization are the main ameliorative measures taken. Trace elements may migrate with the metal–humus complexes. In the Western Cape region of South Africa, deeper rooted orchards and vineyards suffer fewer trace element deficiencies than do shallow-rooted vegetable crops. Most zonal Podzols are under forest; intrazonal Podzols in temperate regions are mostly under forest or shrubs (heath). Tropical Podzols normally sustain a light forest that recovers only slowly after cutting or burning. Mature Podzols are generally best used for extensive grazing or left idle under their natural (climax) vegetation. REGOSOLS Regosols form a taxonomic remnant group containing all soils that could not be accommodated in any of the other RSGs. In practice, Regosols are very weakly developed mineral soils in unconsolidated materials that do not have a mollic or umbric horizon, are not very shallow or very rich in gravels (Leptosols), sandy (Arenosols) or with fluvic materials (Fluvisols). Regosols are extensive in eroding lands, particularly in arid and semi-arid areas and in mountainous terrain. Many Regosols correlate with soil taxa that are marked by incipient soil formation such as: Entisols (United States of America); Rudosols (Australia); Regosole (Germany); Sols peu évolués régosoliques d’érosion or even Sols minéraux bruts d’apport éolien ou volcanique (France); and Neossolos (Brazil). Summary description of Regosols Connotation: Weakly developed soils in unconsolidated material; from Greek rhegos, blanket. Parent material: unconsolidated, finely grained material. Environment: All climate zones without permafrost and at all elevations. Regosols are particularly common in arid areas (including the dry tropics) and in mountain regions. Profile development: No diagnostic horizons. Profile development is minimal as a consequence of young age and/or slow soil formation, e.g. because of aridity. Regional distribution of Regosols Regosols cover an estimated 260 million ha worldwide, mainly in arid areas in the mid-west of the United States of America, northern Africa, the Near East, and Australia. Some 50 million ha of Regosols occur in the dry tropics and another 36 million ha in mountain areas. The extent of most Regosol areas is only limited; consequently, Regosols are common inclusions in other map units on small-scale maps. Management and use of Regosols Regosols in desert areas have minimal agricultural significance. Regosols with rainfall of 500– 1 000 mm/year need irrigation for satisfactory crop production. The low moisture holding capacity of these soils calls for frequent applications of irrigation water; sprinkler or trickle irrigation solves the problem but is rarely economic. Where rainfall exceeds 750 mm/year, the entire profile is raised to its water holding capacity early in the wet season; improvement of dry farming practices may then be a better investment than installation of costly irrigation facilities. Many Regosols are used for extensive grazing. Regosols on colluvial deposits in the loess belt of northern Europe and North America are mostly cultivated; they are planted to small
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grains, sugar beet and fruit trees. Regosols in mountainous regions are delicate and best left under forest. SOLONCHAKS Solonchaks are soils that have a high concentration of soluble salts at some time in the year. Solonchaks are largely confined to the arid and semi-arid climate zones and to coastal regions in all climates. Common international names are saline soils and salt-affected soils. In national soil classification systems, many Solonchaks belong to: halomorphic soils (Russian Federation), Halosols (China), and Salids (United States of America). Summary description of Solonchaks Connotation: Saline soils; from Russian sol, salt. Parent material: Virtually any unconsolidated material. Environment: Arid and semi-arid regions, notably in areas where ascending groundwater reaches the solum or where some surface water is present, with vegetation of grasses and/or halophytic herbs, and in inadequately managed irrigation areas. Solonchaks in coastal areas occur in all climates. Profile development: From weakly to strongly weathered, many Solonchaks have a gleyic colour pattern at some depth. In low-lying areas with a shallow water table, salt accumulation is strongest at the soil surface of the soil (external Solonchaks). Solonchaks where ascending groundwater does not reach the topsoil (or even the solum) have the greatest accumulation of salts at some depth below the soil surface (internal Solonchaks). Regional distribution of Solonchaks The total extent of Solonchaks in the world is estimated at about 260 million ha. Solonchaks are most extensive in the Northern Hemisphere, notably in the arid and semi-arid parts of northern Africa, the Near East, the former Soviet Union and Central Asia; they are also widespread in Australia and the Americas. Management and use of Solonchaks Excessive accumulation of salts in soil affects plant growth in two ways: • The salts aggravate drought stress because dissolved electrolytes create an osmotic potential that affects water uptake by plants. Before any water can be taken up from the soil, plants must compensate the combined forces of the matrix potential of the soil, i.e. the force with which the soil matrix retains water, and the osmotic potential. As a rule of thumb, the osmotic potential of a soil solution (in hectoPascals) amounts to some 650 × EC (dS/m). The total potential that can be compensated by plants (known as the critical leaf water head) varies strongly between plant species. Plant species that stem from the humid tropics have a comparatively low critical leaf water head. For example, green peppers can compensate a total soil moisture potential (matric plus osmotic forces) of only some 3 500 hPa whereas cotton, a crop that evolved in arid and semi-arid climates, survives some 25 000 hPa. • The salts upset the balance of ions in the soil solution because nutrients are proportionately less available. Antagonistic effects are known to exist, e.g. between Na and K, between Na and Ca, and between Mg and K. In higher concentrations, the salts may be directly toxic to plants. Very harmful in this respect are Na ions and chloride ions (they disturb N metabolism). Farmers on Solonchaks adapt their cultivation methods. For example, plants on furrow- irrigated fields are not planted on the top of the ridges but at half height. This ensures that the roots benefit from the irrigation water while salt accumulation is strongest near the top of the ridge, away from the root systems. Strongly salt-affected soils have little agricultural value. They are used for extensive grazing of sheep, goats, camels and cattle, or lie idle. Only after the salts have been flushed from the soil (which then ceases to be a Solonchak) may good yields be hoped for. Application of irrigation water must not only satisfy the needs of the crop, but excess
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water must be applied above the irrigation requirement in order to maintain a downward water flow in the soil and to flush excess salts from the rootzone. Irrigation of crops in arid and semi- arid regions must be accompanied by drainage whereby drainage facilities should be designed to keep the groundwater table below the critical depth. Use of gypsum assists in maintaining hydraulic conductivity while salts are being flushed out with irrigation water. SOLONETZ Solonetz are soils with a dense, strongly structured, clayey subsurface horizon that has a high proportion of adsorbed Na and/or Mg ions. Solonetz that contain free soda (Na2CO3) are strongly alkaline (field pH > 8.5). Common international names are alkali soils and sodic soils. In national soil classification systems many Solonetz correlate with: Sodosols (Australia), the Solonetzic order (Canada), various Solonetz types (Russian Federation), and to the natric Great Groups of several Orders (United States of America). Summary description of Solonetz Connotation: Soils with a high content of exchangeable Na and/or Mg ions; from Russian sol, salt. Parent material: Unconsolidated materials, mostly fine-textured sediments. Environment: Solonetz are normally associated with flat lands in a climate with hot, dry summers, or with (former) coastal deposits that contain a high proportion of Na ions. Major concentrations of Solonetz are in flat or gently sloping grasslands with loess, loam or clay (often derived from loess) in semi-arid, temperate and subtropical regions. Profile development: A black or brown surface soil over a natric horizon with strong round- topped columnar structure elements. Well-developed Solonetz can have an albic eluviation horizon (beginning) directly over the natric horizon. A calcic or gypsic horizon may be present below the natric horizon. Many Solonetz have a field pH of about 8.5, indicative of the presence of free sodium carbonate. Regional distribution of Solonetz Solonetz occur predominantly in areas with a steppe climate (dry summers and an annual precipitation sum of not more than 400–500 mm), in particular in flat lands with impeded vertical and lateral drainage. Smaller occurrences are found on inherently saline parent materials (e.g. marine clays or saline alluvial deposits). Worldwide, Solonetz cover some 135 million ha. Major Solonetz areas are found in Ukraine, Russian Federation, Kazakhstan, Hungary, Bulgaria, Romania, China, United States of America, Canada, South Africa, Argentina and Australia. Management and use of Solonetz The suitability of virgin Solonetz for agricultural uses is dictated almost entirely by the depth and properties of the surface soil. A deep (> 25 cm) humus-rich surface soil is needed for successful arable crop production. However, most Solonetz have only a much shallower surface horizon, or have lost the surface horizon altogether. Solonetz amelioration has two basic elements: • improvement of the porosity of the surface or subsurface soil; • lowering of the ESP. Most reclamation attempts start with incorporation of gypsum or, exceptionally, calcium chloride in the soil. Where lime or gypsum occur at shallow depth in the soil body, deep ploughing (mixing the carbonate or gypsum containing subsoil with the surface soil) may make expensive amendments superfluous. Traditional reclamation strategies start with the planting of an Na-resistant crop, e.g. Rhodes grass, to gradually improve the permeability of the soil. Once a functioning pore system is in place, Na ions are carefully leached from the soil with good- quality (Ca-rich) water (relatively pure water should be avoided because it exacerbates the dispersion problem). An extreme reclamation method (developed in Armenia and applied successfully to Solonetz with a calcic or petrocalcic horizon in the Arax Valley) uses diluted sulphuric acid (a waste
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product of the metallurgical industry) to dissolve CaCO3 contained in the soil. This brings Ca ions in the soil solution, which displace exchangeable Na. The practice improves soil aggregation and soil permeability. The resulting sodium sulphate (in the soil solution) is subsequently flushed out of the soil. In India, pyrite was applied to Solonetz to produce sulphuric acid, thus lowering extreme alkalinity and overcoming Fe deficiency. Ameliorated Solonetz can produce a fair crop foodgrain or forage. The majority of the world’s Solonetz have never been reclaimed and are used for extensive grazing or lie idle. STAGNOSOLS Stagnosols are soils with a perched water table showing redoximorphic features caused by surface water. Stagnosols are periodically wet and mottled in the topsoil and subsoil, with or without concretions and/or bleaching. A common name in many national classification systems for most Stagnosols is pseudogley. In the US Soil Taxonomy, many of them belong to the Aqualfs, Aquults, Aquents, Aquepts and Aquolls. Summary description of Stagnosols Connotation: From Latin stagnare, to flood. Parent material: A wide variety of unconsolidated materials including glacial till, and loamy aeolian, alluvial and colluvial deposits, but also physically weathered silt stone. Environment: Most common in flat or gently sloping land in cool temperate to subtropical regions with humid to perhumid climate conditions. Profile development: Strong mottling due to redox processes caused by stagnating water Similar to strongly mottled Luvisols, Cambisols or Umbrisols; the topsoil can also be completely bleached (albic horizon). Regional distribution of Stagnosols Stagnosols cover 150–200 million ha worldwide; for the greater part in humid to perhumid temperate regions of West and Central Europe, North America, southeast Australia, and Argentina, associated with Luvisols as well as silty to clayey Cambisols and Umbrisols. They also occur in humid to perhumid subtropical regions, associated with Acrisols and Planosols. Management and use of Stagnosols The agricultural suitability of Stagnosols is limited because of their oxygen deficiency resulting from stagnating water above a dense subsoil. Therefore, they have to be drained. However, in contrast to Gleysols, drainage with channels or pipes is in many cases insufficient. It is necessary to have a higher porosity in the subsoil in order to improve the hydraulic conductivity. This may be achieved by deep loosening or deep ploughing. Drained Stagnosols can be fertile soils owing to their moderate degree of leaching. TECHNOSOLS Technosols comprise a new RSG and combine soils whose properties and pedogenesis are dominated by their technical origin. They contain a significant amount of artefacts (something in the soil recognizably made or extracted from the earth by humans), or are sealed by technic hard rock (hard material created by humans, having properties unlike natural rock). They include soils from wastes (landfills, sludge, cinders, mine spoils and ashes), pavements with their underlying unconsolidated materials, soils with geomembranes and constructed soils in human-made materials. Technosols are often referred to as urban or mine soils. They are recognized in the new Russian soil classification system as Technogenic Superficial Formations. Summary description of Technosols Connotation: Soils dominated or strongly influenced by human-made material; from Greek technikos, skilfully made.
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Parent material: All kinds of materials made or exposed by human activity that otherwise would not occur at the Earth’s surface; pedogenesis in these soils is affected strongly by materials and their organization. Environment: Mostly in urban and industrial areas, in small areas, although in a complex pattern associated with other groups. Profile development: Generally none, although in old dumps (e.g. Roman rubble) evidence of natural pedogenesis can be observed, such as clay translocation. Lignite and fly ash deposits may exhibit over time vitric or andic properties (Zikeli, Kastler and Jahn, 2004; Zevenbergen et al., 1999). Original profile development may still be present in contaminated natural soils. Regional distribution of Technosols Technosols are found throughout the world where human activity has led to the construction of artificial soil, sealing of natural soil, or extraction of material normally not affected by surface processes. Thus, cities, roads, mines, refuse dumps, oil spills, coal fly ash deposits and the like are included in Technosols. Management and use of Technosols Technosols are affected strongly by the nature of the material or the human activity that placed it. They are more likely to be contaminated than soils from other RSGs. Many Technosols have to be treated with care as they may contain toxic substances resulting from industrial processes. Many Technosols, in particular the ones in refuse dumps, are currently covered with a layer of natural soil material in order to permit revegetation. Such a layer forms part of the Technosol, provided that the requirement of 20 percent or more (by volume, by weighted average) artefacts in the upper 100 cm of the soil surface or to continuous rock or a cemented or indurated layer, whichever is shallower, of the Technosol definition is met. UMBRISOLS Umbrisols accommodate soils in which organic matter has accumulated within the mineral surface soil (in most cases with low base saturation) to the extent that it significantly affects the behaviour and utilization of the soil. Umbrisols are the logical counterpart of soils with a mollic horizon and a high base saturation throughout (Chernozems, Kastanozems and Phaeozems). Not previously recognized at such a high taxonomic level, many of these soils are classified in other systems as: several Great Groups of Entisols and Inceptisols (United States of America); Humic Cambisols and Umbric Regosols (FAO); Sombric Brunisols and Humic Regosols (France); Much Very dark-humus soils (Russian Federation); Brown Podzolic soils (e.g. Indonesia); and Umbrisols (Romania). Summary description of Umbrisols Connotation: Soils with dark topsoil; from Latin umbra, shade. Parent material: Weathering material of siliceous rock. Environment: Humid climates; common in mountainous regions with little or no moisture deficit, in mostly cool areas but including tropical and subtropical mountains. Profile development: Dark brown umbric (seldom: mollic) surface horizon, in many cases over a cambic subsurface horizon with low base saturation. Regional distribution of Umbrisols Umbrisols occur in cool, humid regions, mostly mountainous and with little or no soil moisture deficit. They occupy about 100 million ha throughout the world. In South America, Umbrisols are common in the Andean ranges of Colombia, Ecuador and, to a lesser extent, in Venezuela, Bolivia and Peru. They also occur in Brazil, e.g. in the Serra do Mar, and in Lesotho and South Africa, e.g. in the Drakensberg range. Umbrisols in North America are confined largely to the northwest Pacific seaboard. In Europe, Umbrisols occur along the northwest Atlantic seaboard, e.g. in Iceland, on the British Isles and in northwest Portugal and Spain. In Asia, they are found in the mountain ranges east and west of Lake Baikal, and on fringes of the Himalayas, notably in India, Nepal, China and Myanmar. Umbrisols occur at lower altitudes in Manipur (eastern
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India), in the Chin Hills (western Myanmar) and in Sumatra (Barisan range). In Oceania, Umbrisols are found in the mountain ranges of Papua New Guinea and southeast Australia and in the eastern parts of South Island, New Zealand. Management and use of Umbrisols Many Umbrisols are under a natural or near-natural vegetation cover. Umbrisols above the actual tree line in the Andean, Himalayan and Central Asian mountain ranges, or at lower altitudes in northern and western Europe where the former forest vegetation has been largely cleared, carry a vegetation of short grasses of low nutritional value. Coniferous forest predominates in Brazil (e.g. Araucaria spp.) and in the United States of America (mainly Thuja, Tsuga and Pseudotsuga spp.). Umbrisols in tropical mountain areas in South Asia and Oceania are under montane evergreen forest. In the mountains of southern Mexico, the vegetation varies from tropical semi-deciduous forest to much cooler montane cloud forest. The predominance of sloping land and wet and cool climate conditions restricts utilization of many Umbrisols to extensive grazing. Management focuses on the introduction of improved grasses and correction of the soil pH by liming. Many Umbrisols are susceptible to erosion. The planting of perennial crops and bench or contour terracing offer possibilities for permanent agriculture on gentler slopes. Where conditions are suitable, cash crops may be grown, e.g. cereals and root crops in the United States of America, Europe and South America, or tea and cinchona in South Asia (Indonesia). Highland coffee on Umbrisols demands high management inputs to meet its stringent nutrient requirements. In New Zealand, Umbrisols have been transformed into highly productive soils, used for intensive sheep and dairy farming, and production of cash crops. VERTISOLS Vertisols are churning, heavy clay soils with a high proportion of swelling clays. These soils form deep wide cracks from the surface downward when they dry out, which happens in most years. The name Vertisols (from Latin vertere, to turn) refers to the constant internal turnover of soil material. Common local names for many Vertisols are: black cotton soils, regur (India), black turf soils (South Africa), margalites (Indonesia), Vertosols (Australia), Vertissolos (Brazil), and Vertisols (United States of America). Summary description of Vertisols Connotation: Churning, heavy clay soils; from Latin vertere, to turn. Parent material: Sediments that contain a high proportion of swelling clays, or swelling clays products of produced by neoformation from rock weathering that have the characteristics of swelling clays. Environment: Depressions and level to undulating areas, mainly in tropical, subtropical, semi- arid to subhumid and humid climates with an alternation of distinct wet and dry seasons. The climax vegetation is savannah, natural grassland and/or woodland. Profile development: Alternate swelling and shrinking of expanding clays results in deep cracks in the dry season, and formation of slickensides and wedge-shaped structural elements in the subsurface soil. Gilgai microrelief is peculiar to Vertisols although not commonly encountered. Regional distribution of Vertisols Vertisols cover 335 million ha worldwide. An estimated 150 million ha is potential cropland. Vertisols in the tropics cover some 200 million ha; one-quarter of this is considered to be useful land. Most Vertisols occur in the semi-arid tropics, with an average annual rainfall of 500– 1 000 mm, but Vertisols are also found in the wet tropics, e.g. Trinidad (where the annual rainfall sum amounts to 3 000 mm). The largest Vertisol areas are on sediments that have a high content of smectitic clays or that produce such clays upon post-depositional weathering (e.g. in the Sudan), and on extensive basalt plateaus (e.g. in India and Ethiopia). Vertisols are also prominent in South Africa, Australia, the southwest of the United States of America (Texas), Uruguay, Paraguay and Argentina. Vertisols are typically found in lower landscape positions
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such as dry lake bottoms, river basins, lower river terraces, and other lowlands that are periodically wet in their natural state. Management and use of Vertisols Large areas of Vertisols in the semi-arid tropics are still unused or are used only for extensive grazing, wood chopping, charcoal burning and the like. These soils have considerable agricultural potential, but adapted management is a precondition for sustained production. The comparatively good chemical fertility and their occurrence on extensive level plains where reclamation and mechanical cultivation can be envisaged are assets of Vertisols. Their physical soil characteristics and, notably, their difficult water management cause problems. Buildings and other structures on Vertisols are at risk, and engineers have to take special precautions to avoid damage. The agricultural uses of Vertisols range from very extensive (grazing, collection of fuelwood, and charcoal burning) through smallholder post-rainy season crop production (millet, sorghum, cotton and chickpeas) to small-scale (rice) and large-scale irrigated agriculture (cotton, wheat, barley, sorghum, chickpeas, flax, noug [Guzotia abessynica] and sugar cane). Cotton is known to perform well on Vertisols, allegedly because cotton has a vertical root system that is not damaged severely by cracking of the soil. Tree crops are generally less successful because tree roots find it difficult to establish themselves in the subsoil and are damaged as the soil shrinks and swells. Management practices for crop production should be directed primarily at water control in combination with conservation or improvement of soil fertility. The physical properties and the soil moisture regime of Vertisols represent serious management constraints. The heavy soil texture and domination of expanding clay minerals result in a narrow soil moisture range between moisture stress and water excess. Tillage is hindered by stickiness when the soil is wet and hardness when it is dry. The susceptibility of Vertisols to waterlogging may be the single most important factor that reduces the actual growing period. Excess water in the rainy season must be stored for post-rainy season use (water harvesting) on Vertisols with very slow infiltration rates. One compensation for the shrink–swell characteristics is the phenomenon of self-mulching that is common on many Vertisols. Large clods produced by primary tillage break down with gradual drying into fine peds, which provide a passable seed bed with minimal effort. For the same reason, gully erosion on overgrazed Vertisols is seldom severe because gully walls soon assume a shallow angle of repose, which allows grass to become re-established more readily.
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Chapter 5 Definitions of formative elements for second-level units of the WRB
The definitions of the formative elements for the second-level units relate to RSGs, diagnostic horizons, properties and materials, attributes such as colour, chemical conditions, texture, etc. Reference to the RSGs defined in Chapters 3 and 4 and the diagnostic features listed in Chapter 2 is given in italics. Usually, only a limited number of combinations will be possible; most of the definitions are mutually exclusive. Abruptic (ap): having an abrupt textural change within 100 cm of the soil surface. Aceric (ae): having a pH (1:1 in water) between 3.5 and 5 and jarosite mottles in some layer within 100 cm of the soil surface (in Solonchaks only). -1 Acric (ac): having an argic horizon that has a CEC (by 1 M NH4OAc) of less than 24 cmolc kg clay in some part to a maximum depth of 50 cm below its upper limit, either starting within 100 cm of the soil surface or within 200 cm of the soil surface if the argic horizon is overlain by loamy sand or coarser textures throughout, and having a base saturation (by 1 M NH4OAc) of less than 50 percent in the major part between 50 and 100 cm from the soil surface. -1 Acroxic (ao): having less than 2 cmolc kg fine earth exchangeable bases plus 1 M KCl exchangeable Al3+ in one or more layers with a combined thickness of 30 cm or more within 100 cm of the soil surface (in Andosols only). Albic (ab): having an albic horizon starting within 100 cm of the soil surface. Hyperalbic (ha): having an albic horizon starting within 50 cm of the soil surface and having its lower boundary at a depth of 100 cm or more from the soil surface. Glossalbic (gb): showing tonguing of an albic into an argic or natric horizon. Alcalic (ax): having a pH (1:1 in water) of 8.5 or more throughout within 50 cm of the soil surface or to continuous rock or a cemented or indurated layer, whichever is shallower. -1 Alic (al): having an argic horizon that has a CEC (by 1 M NH4OAc) of 24 cmolc kg clay or more throughout or to a depth of 50 cm below its upper limit, whichever is shallower, either starting within 100 cm of the soil surface or within 200 cm of the soil surface if the argic horizon is overlain by loamy sand or coarser textures throughout, and having a base saturation (by 1 M NH4OAc) of less than 50 percent in the major part between 50 and 100 cm from the soil surface. Aluandic (aa): having one or more layers, cumulatively 30 15 cm or more thick, with andic properties and an acid oxalate (pH 3) extractable silica content of less than 0.6 percent, and an 54 55 Alpy /Alox of 0.5 or more, within 100 cm of the soil surface (in Andosols only). Thaptaluandic (aab): having one or more buried layers, cumulatively 30 15 cm or more thick, with andic properties and an acid oxalate (pH 3) extractable silica content of less 56 57 than 0.6 percent, or an Alpy /Alox of 0.5 or more, within 100 cm of the soil surface.
54 Alpy: pyrophosphate-extractable aluminium, expressed as percent of the fine earth (0–2 mm) fraction on an oven- dried (105 °C) basis. 55 Alox: acid oxalate-extractable aluminium (Blakemore, Searle and Daly, 1981), expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105 °C) basis. 56 Alpy: pyrophosphate-extractable aluminium, expressed as percent of the fine earth (0–2 mm) fraction on an oven- dried (105o C) basis.
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Alumic (au): having an Al saturation (effective) of 50 percent or more in some layer between 50 and 100 cm from the soil surface. Andic (an): having within 100 cm of the soil surface one or more layers with andic or vitric properties with a combined thickness of 30 cm or more (in Cambisols 15 cm or more), of which 15, cumulatively 30 cm or more (in Cambisols 7.5 cm or more) thick, with have andic properties, within 100 cm of the soil surface. Thaptandic (ba): having within 100 cm of the soil surface one or more buried layers with andic or vitric properties with a combined thickness of 30 cm or more (in Cambisols 15 cm or more), of which 15, cumulatively 30 cm or more (in Cambisols 7.5 cm or more) thick, with have andic properties, within 100 cm of the soil surface. Anthraquic (aq): having an anthraquic horizon. Anthric (am): having an anthric horizon. Arenic (ar): having a texture of loamy fine sand or coarser in a layer, 30 cm or more thick, within 100 cm of the soil surface. Epiarenic (arp): having a texture of loamy fine sand or coarser in a layer, 30 cm or more thick, within 50 cm of the soil surface. Endoarenic (arn): having a texture of loamy fine sand or coarser in a layer, 30 cm or more thick, between 50 and 100 cm from the soil surface. Aric (ai): having only remnants of diagnostic horizons – disturbed by deep ploughing. Aridic (ad): having aridic properties without a takyric or yermic horizon. Arzic (az): having sulphate-rich groundwater in some layer within 50 cm of the soil surface during some time in most years and containing 15 percent or more gypsum averaged over a depth of 100 cm from the soil surface or to continuous rock or a cemented or indurated layer, whichever is shallower (in Gypsisols only). Brunic (br): having a layer, 15 cm or more thick, which meets criteria 2–4 of the cambic horizon but fails criterion 1 and does not form part of an albic horizon, starting within 50 cm of the soil surface. Calcaric (ca): having calcaric material between 20 and 50 cm from the soil surface or between 20 cm and continuous rock or a cemented or indurated layer, whichever is shallower. Calcic (cc): having a calcic horizon or concentrations of secondary carbonates starting within 100 cm of the soil surface. Pisocalcic (cp): having only concentrations of secondary carbonates starting within 100 cm of the soil surface. Cambic (cm): having a cambic horizon, which does not form part of an albic horizon, starting within 50 cm of the soil surface. Carbic (cb): having a spodic horizon that does not turn redder on ignition throughout (in Podzols only). Carbonatic (cn): having a salic horizon with a soil solution (1:1 in water) with a pH of 8.5 or - 2- - more and [HCO3 ] > [SO4 ] >> [Cl ] (in Solonchaks only). - 2- Chloridic (cl): having a salic horizon with a soil solution (1:1 in water) with [Cl ] >> [SO4 ] > - [HCO3 ] (in Solonchaks only). Chromic (cr): having within 150 cm of the soil surface a subsurface layer, 30 cm or more thick, that has a Munsell hue redder than 7.5 YR or that has both, a hue of 7.5 YR and a chroma, moist, of more than 4. Clayic (ce): having a texture of clay in a layer, 30 cm or more thick, within 100 cm of the soil surface. Epiclayic (cep): having a texture of clay in a layer, 30 cm or more thick, within 50 cm of the soil surface.
57 Alox: acid oxalate-extractable aluminium (Blakemore, Searle and Daly, 1981), expressed as percent of the fine earth (0–2 mm) fraction on an oven-dried (105 °C) basis.
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Endoclayic (cen): having a texture of clay in a layer, 30 cm or more thick, within 50 and 100 cm of the soil surface. Colluvic (co): having colluvic material, 20 cm or more thick, created by human-induced lateral movement. Cryic (cy): having a cryic horizon starting within 100 cm of the soil surface or having a cryic horizon starting within 200 cm of the soil surface with evidence of cryoturbation in some layer within 100 cm of the soil surface. Cutanic (ct): having clay coatings in some parts of an argic horizon either starting within 100 cm of the soil surface or within 200 cm of the soil surface if the argic horizon is overlain by loamy sand or coarser textures throughout. Densic (dn): having natural or artificial compaction within 50 cm of the soil surface to the extent that roots cannot penetrate. Drainic (dr): having a histic horizon that is drained artificially starting within 40 cm of the soil surface. Duric (du): having a duric horizon starting within 100 cm of the soil surface. Endoduric (nd): having a duric horizon starting between 50 and 100 cm from the soil surface. Hyperduric (duh): having a duric horizon with 50 percent or more (by volume) durinodes or fragments of a broken-up petroduric horizon starting within 100 cm of the soil surface. Dystric (dy): having a base saturation (by 1 M NH4OAc) of less than 50 percent in the major part between 20 and 100 cm from the soil surface or between 20 cm and continuous rock or a cemented or indurated layer, or, in Leptosols, in a layer, 5 cm or more thick, directly above continuous rock, if the continuous rock starts within 25 cm of the soil surface. Endodystric (ny): having a base saturation (by 1 M NH4OAc) of less than 50 percent throughout between 50 and 100 cm from the soil surface. Epidystric (ed): having a base saturation (by 1 M NH4OAc) of less than 50 percent throughout between 20 and 50 cm from the soil surface. Hyperdystric (hd): having a base saturation (by 1 M NH4OAc) of less than 50 percent throughout between 20 and 100 cm from the soil surface, and less than 20 percent in some layer within 100 cm of the soil surface. Orthodystric (dyo): having a base saturation (by 1 M NH4OAc) of less than 50 percent throughout between 20 and 100 cm from the soil surface. Ekranic (ek): having technic hard rock starting within 5 cm of the soil surface and covering 95 percent or more of the horizontal extent of a pedon the soil (in Technosols only). Endoduric (nd): see Duric. Endodystric (ny): see Dystric. Endoeutric (ne): see Eutric. Endofluvic (nf): see Fluvic. Endogleyic (ng): see Gleyic. Endoleptic (nl): see Leptic. Endosalic (ns): see Salic. Entic (et): not having an albic horizon and having a loose spodic horizon (in Podzols only). Epidystric (ed): see Dystric. Epieutric (ee): see Eutric. Epileptic (el): see Leptic. Episalic (ea): see Salic. Escalic (ec): occurring in human-made terraces. Eutric (eu): having a base saturation (by 1 M NH4OAc) of 50 percent or more in the major part between 20 and 100 cm from the soil surface or between 20 cm and continuous rock or a cemented or indurated layer, or, in Leptosols, in a layer, 5 cm or more thick, directly above continuous rock, if the continuous rock starts within 25 cm of the soil surface.
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Endoeutric (ne): having a base saturation (by 1 M NH4OAc) of 50 percent or more throughout between 50 and 100 cm from the soil surface. Epieutric (ee): having a base saturation (by 1 M NH4OAc) of 50 percent or more throughout between 20 and 50 cm from the soil surface. Hypereutric (he): having a base saturation (by 1 M NH4OAc) of 50 percent or more throughout between 20 and 100 cm from the soil surface and 80 percent or more in some layer within 100 cm of the soil surface. Orthoeutric (euo): having a base saturation (by 1 M NH4OAc) of 50 percent or more throughout between 20 and 100 cm from the soil surface. Eutrosilic (es): having one or more layers, cumulatively 30 cm or more thick, with andic -1 properties and a sum of exchangeable bases of 15 cmolc kg fine earth or more within 100 cm of the surface (in Andosols only). Ferralic (fl): having a ferralic horizon starting within 200 cm of the soil surface (in Anthrosols only), or having ferralic properties in at least some layer starting within 100 cm of the soil surface (in other soils). 58 Hyperferralic (flh): having ferralic properties and a CEC (by 1 M NH4OAc) of less -1 than 16 cmolc kg clay in at least some layer starting within 100 cm of the soil surface. Hypoferralic (flw): having in a layer, 30 cm or more thick, starting within 100 cm of the -1 soil surface a CEC (by 1 M NH4OAc) of less than 4 cmolc kg fine earth and a Munsell chroma, moist, of 5 or more or a hue redder than 10 YR (in Arenosols only). Ferric (fr): having a ferric horizon starting within 100 cm of the soil surface. Hyperferric (frh): having a ferric horizon with 40 percent or more of the volume discrete reddish to blackish nodules starting within 100 cm of the soil surface. Fibric (fi): having, after rubbing, two-thirds or more (by volume) of the organic material consisting of recognizable plant tissue within 100 cm of the soil surface (in Histosols only). Floatic (ft): having organic material floating on water (in Histosols only). Fluvic (fv): having fluvic material in a layer, 25 cm or more thick, within 100 cm of the soil surface. Endofluvic (nf): having fluvic material in a layer, 25 cm or more thick, between 50 and 100 cm from the soil surface. Folic (fo): having a folic horizon starting within 40 cm of the soil surface. Thaptofolic (fob): having a buried folic horizon starting between 40 and 100 cm from the soil surface. Fractipetric (fp): having a strongly cemented or indurated horizon consisting of fractured or broken clods with an average horizontal length of less than 10 cm, starting within 100 cm of the soil surface. Fractiplinthic (fa): having a petroplinthic horizon consisting of fractured or broken clods with an average horizontal length of less than 10 cm, starting within 100 cm of the soil surface. Fragic (fg): having a fragic horizon starting within 100 cm of the soil surface. Fulvic (fu): having a fulvic horizon starting within 30 cm of the soil surface. Garbic (ga): having a layer, 20 cm or more thick within 100 cm of the soil surface, with 20 percent or more (by volume, by weighted average) artefacts containing 35 percent or more (by volume) organic waste materials (in Technosols only). Gelic (ge): having a layer with a soil temperature of 0 °C or less for two or more consecutive years starting within 200 cm of the soil surface. Gelistagnic (gt): having temporary water saturation at the soil surface caused by a frozen subsoil. Geric (gr): having geric properties in some layer within 100 cm of the soil surface. Gibbsic (gi): having a layer, 30 cm or more thick, containing 25 percent or more gibbsite in the fine earth fraction starting within 100 cm of the soil surface.
58 See Annex 1.
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Glacic (gc): having a layer, 30 cm or more thick, containing 75 percent (by volume) or more ice starting within 100 cm of the soil surface. Gleyic (gl): having within 100 cm of the mineral soil surface a layer, 25 cm or more thick, that has in some parts reducing conditions in some parts and in 25 percent or more of the soil volume a gleyic colour pattern throughout. Endogleyic (ng): having between 50 and 100 cm from the mineral soil surface a layer, 25 cm or more thick, that has in some parts reducing conditions in some parts and in 25 percent or more of the soil volume a gleyic colour pattern throughout. Epigleyic (glp): having within 50 cm of the mineral soil surface a layer, 25 cm or more thick, that has in some parts reducing conditions in some parts and in 25 percent or more of the soil volume a gleyic colour pattern throughout. Glossalbic (gb): see Albic. Glossic (gs): showing tonguing of a mollic or umbric horizon into an underlying layer. Molliglossic (mi): showing tonguing of a mollic horizon into an underlying layer. Umbriglossic (ug): showing tonguing of an umbric horizon into an underlying layer. Greyic (gz): having Munsell colours with a chroma of 3 or less when moist, a value of 3 or less when moist and 5 or less when dry and uncoated silt and sand grains on structural faces within 5 cm of the mineral soil surface. Grumic (gm): having a soil surface layer with a thickness of 3 cm or more with a strong structure finer than very coarse granular (in Vertisols only). Gypsic (gy): having a gypsic horizon starting within 100 cm of the soil surface. Gypsiric (gp): having gypsiric material between 20 and 50 cm from the soil surface or between 20 cm and continuous rock or a cemented or indurated layer, whichever is shallower. Haplic (ha): having a typical expression of certain features (typical in the sense that there is no further or meaningful characterization) and only used if none of the preceding qualifiers applies. Hemic (hm): having, after rubbing, between two-thirds and one-sixth (by volume) of the organic material consisting of recognizable plant tissue within 100 cm from the soil surface (in Histosols only). Histic (hi): having a histic horizon starting within 40 cm of the soil surface. Thaptohistic (hib): having a buried histic horizon starting between 40 and 100 cm from the soil surface. Hortic (ht): having a hortic horizon. Humic (hu): having the following organic carbon contents in the fine earth fraction as a weighted average: in Ferralsols and Nitisols, 1.4 percent or more to a depth of 100 cm from the mineral soil surface; in Leptosols to which the Hyperskeletic qualifier applies, 2 percent or more to a depth of 25 cm from the mineral soil surface; in other soils, 1 percent or more to a depth of 50 cm from the mineral soil surface. Hyperhumic (huh): having an organic carbon content of 5 percent or more as a weighted average in the fine earth fraction to a depth of 50 cm from the mineral soil surface. Hydragric (hg): having an anthraquic horizon and an underlying hydragric horizon, the latter starting within 100 cm of the soil surface. Hydric (hy): having within 100 cm of the soil surface one or more layers with a combined thickness of 35 cm or more, which have a water retention at 1 500 kPa (in undried samples) of 100 percent or more (in Andosols only). Hydrophobic (hf): water-repellent, i.e. water stands on a dry soil for the duration of 60 seconds or more (in Arenosols only). Hyperalbic (hab): see Albic. Hyperalic (hl): having an argic horizon, either starting within 100 cm of the soil surface or within 200 cm of the soil surface if the argic horizon is overlain by loamy sand or coarser textures throughout, that has a silt to clay ratio of less than 0.6 and an Al saturation (effective) of 50 percent or more, throughout or to a depth of 50 cm below its upper limit, whichever is shallower (in Alisols only).
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Hypercalcic (hc): having a calcic horizon with 50 percent or more (by mass) calcium carbonate equivalent and starting within 100 cm of the soil surface (in Calcisols only). Hyperdystric (hd): see Dystric. Hypereutric (he): see Eutric. Hypergypsic (hp): having a gypsic horizon with 50 percent or more (by mass) gypsum and starting within 100 cm of the soil surface (in Gypsisols only). Hyperochric (ho): having a mineral topsoil layer, 5 cm or more thick, with a Munsell value, dry, of 5.5 or more that turns darker on moistening, an organic carbon content of less than 0.4 percent, a platy structure in 50 percent or more of the volume, and a surface crust. Hypersalic (hs): see Salic. Hyperskeletic (hk): containing less than 20 percent (by volume) fine earth averaged over a depth of 75 cm from the soil surface or to continuous rock, whichever is shallower. Hypocalcic (wc): having a calcic horizon with a calcium carbonate equivalent content in the fine earth fraction of less than 25 percent and starting within 100 cm of the soil surface (in Calcisols only). Hypogypsic (wg): having a gypsic horizon with a gypsum content in the fine earth fraction of less than 25 percent and starting within 100 cm of the soil surface (in Gypsisols only). Hypoluvic (wl): having an absolute clay increase of 3 percent or more within 100 cm of the soil surface (in Arenosols only). Hyposalic (ws): see Salic. Hyposodic (wn): see Sodic. Irragric (ir): having an irragric horizon. Lamellic (ll): having clay lamellae with a combined thickness of 15 cm or more within 100 cm of the soil surface. Laxic (la): having a bulk density of less than 0.89 kg dm-3, in a mineral soil layer, 20 cm or more thick, starting within 75 cm of the soil surface. Leptic (le): having continuous rock starting within 100 cm of the soil surface. Endoleptic (nl): having continuous rock starting between 50 and 100 cm from the soil surface. Epileptic (el): having continuous rock starting within 50 cm of the soil surface. Lignic (lg): having inclusions of intact wood fragments, which make up one-quarter or more of the soil volume, within 50 cm of the soil surface (in Histosols only). Limnic (lm): having limnic material, cumulatively 10 cm or more thick, within 50 cm of the soil surface. Linic (lc): having a continuous, very slowly permeable to impermeable constructed geomembrane of any thickness starting within 100 cm of the soil surface. Lithic (li): having continuous rock starting within 10 cm of the soil surface (in Leptosols only). Nudilithic (nt): having continuous rock at the soil surface (in Leptosols only). -1 Lixic (lx): having an argic horizon that has a CEC (by 1 M NH4OAc) of less than 24 cmolc kg clay or more in some part to a maximum depth of 50 cm below its upper limit, either starting within 100 cm of the soil surface or within 200 cm of the soil surface if the argic horizon is overlain by loamy sand or coarser textures throughout, and having a base saturation (by 1 M NH4OAc) of 50 percent or more in the major part between 50 and 100 cm from the soil surface. -1 Luvic (lv): having an argic horizon that has a CEC (by 1 M NH4OAc) of 24 cmolc kg clay or more throughout or to a depth of 50 cm below its upper limit, whichever is shallower, either starting within 100 cm of the soil surface or within 200 cm of the soil surface if the argic horizon is overlain by loamy sand or coarser textures throughout, and having a base saturation (by 1 M NH4OAc) of 50 percent or more in the major part between 50 and 100 cm from the soil surface. Magnesic (mg): having an exchangeable Ca to Mg ratio of less than 1 in the major part within 100 cm of the soil surface or to continuous rock or a cemented or indurated layer, whichever is shallower.
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Manganiferric (mf): having a ferric horizon starting within 100 cm of the soil surface in which half or more of the nodules or mottles are black. Mazic (mz): massive and hard to very hard in the upper 20 cm of the soil (in Vertisols only). Melanic (ml): having a melanic horizon starting within 30 cm of the soil surface (in Andosols only). Mesotrophic (ms): having a base saturation (by 1 M NH4OAc) of less than 75 percent at a depth of 20 cm from the soil surface (in Vertisols only). Mollic (mo): having a mollic horizon. Molliglossic (mi): see Glossic. Natric (na): having a natric horizon starting within 100 cm of the soil surface. Nitic (ni): having a nitic horizon starting within 100 cm of the soil surface. Novic (nv): having above the soil that is classified at the RSG level, a layer with recent sediments (new material), 5 cm or more and less than 50 cm thick. Areninovic (anv): having above the soil that is classified at the RSG level, a layer with recent sediments (new material), 5 cm or more and less than 50 cm thick, which has a texture of loamy fine sand or coarser in its major part. Clayinovic (cnv): having above the soil that is classified at the RSG level, a layer with recent sediments (new material), 5 cm or more and less than 50 cm thick, which has a texture of clay in its major part. Siltinovic (snv): having above the soil that is classified at the RSG level, a layer with recent sediments (new material), 5 cm or more and less than 50 cm thick, which has a texture of silt, silt loam, silty clay loam or silty clay in its major part. Nudiargic (ng): having an argic horizon starting at the mineral soil surface. Nudilithic (nt): see Lithic. Ombric (om): having a histic horizon saturated predominantly with rainwater starting within 40 cm of the soil surface (in Histosols only). Ornithic (oc): having a layer 15 cm or more thick with ornithogenic material starting within 50 cm of the soil surface. Ortsteinic (os): having a cemented spodic horizon (ortstein) (in Podzols only). Oxyaquic (oa): saturated with oxygen-rich water during a period of 20 or more consecutive days and not having a gleyic or stagnic colour pattern in some layer within 100 cm of the soil surface. Pachic (ph): having a mollic or umbric horizon 50 cm or more thick. Pellic (pe): having in the upper 30 cm of the soil a Munsell value, moist, of 3.5 or less and a chroma, moist, of 1.5 or less (in Vertisols only). Petric (pt): having a strongly cemented or indurated layer starting within 100 cm of the soil surface. Endopetric (ptn): having a strongly cemented or indurated layer starting between 50 and 100 cm from the soil surface. Epipetric (ptp): having a strongly cemented or indurated layer starting within 50 cm of the soil surface. Petrocalcic (pc): having a petrocalcic horizon starting within 100 cm of the soil surface. Petroduric (pd): having a petroduric horizon starting within 100 cm of the soil surface. Petrogleyic (py): having a layer, 10 cm or more thick, with an oximorphic colour pattern59, 15 percent or more (by volume) of which is cemented (bog iron), within 100 cm of the soil surface. Petrogypsic (pg): having a petrogypsic horizon starting within 100 cm of the soil surface. Petroplinthic (pp): having a petroplinthic horizon starting within 100 cm of the soil surface. Petrosalic (ps): having, within 100 cm of the soil surface, a layer, 10 cm or more thick, which is cemented by salts more soluble than gypsum.
59 As defined in the gleyic colour pattern.
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Pisocalcic (cp): see Calcic. Pisoplinthic (px): having a pisoplinthic horizon starting within 100 cm of the soil surface. Placic (pi): having, within 100 cm of the soil surface, an iron pan, between 1 and 25 mm thick, that is continuously cemented by a combination of organic matter, Fe and/or Al. Plaggic (pa): having a plaggic horizon. Plinthic (pl): having a plinthic horizon starting within 100 cm of the soil surface. Posic (po): having a zero or positive charge (pHKCl - pHwater ≥ 0, both in 1:1 solution) in a layer, 30 cm or more thick, starting within 100 cm of the soil surface (in Plinthosols and Ferralsols only). Profondic (pf): having an argic horizon in which the clay content does not decrease by 20 percent or more (relative) from its maximum within 150 cm of the soil surface. Protic (pr): showing no soil horizon development (in Arenosols only). Puffic (pu): having a crust pushed up by salt crystals (in Solonchaks only). Reductaquic (ra): saturated with water during the thawing period and having at some time of the year reducing conditions above a cryic horizon and within 100 cm of the soil surface (in Cryosols only). Reductic (rd): having reducing conditions in 25 percent or more of the soil volume within 100 cm of the soil surface caused by gaseous emissions, e.g. methane or carbon dioxide (in Technosols only). Regic (rg): not having buried horizons (in Anthrosols only). Rendzic (rz): having a mollic horizon that contains or immediately overlies calcaric materials or calcareous rock containing 40 percent or more calcium carbonate equivalent. Rheic (rh): having a histic horizon saturated predominantly with groundwater or flowing surface water starting within 40 cm of the soil surface (in Histosols only). Rhodic (ro): having within 150 cm of the soil surface a subsurface layer, 30 cm or more thick, with a Munsell hue of redder than 5 YR (2.5 YR or redder), a value, moist, of less than 3.5 and a value, dry, no more than one unit higher than the moist value. Rubic (ru): having within 100 cm of the soil surface a subsurface layer, 30 cm or more thick, with a Munsell hue redder than 10 YR or a chroma, moist, of 5 or more (in Arenosols only). Ruptic (rp): having a lithological discontinuity within 100 cm of the soil surface. Rustic (rs): having a spodic horizon in which the ratio of the percentage of acid oxalate (pH3) extractable Fe to the percentage of organic carbon is 6 or more throughout that turns redder on ignition (in Podzols only). Salic (sz): having a salic horizon starting within 100 cm of the soil surface. Endosalic (ns): having a salic horizon starting between 50 and 100 cm from the soil surface. Episalic (ea): having a salic horizon starting within 50 cm of the soil surface. -1 Hypersalic (hs): having an ECe of 30 dS m or more at 25 °C in some layer within 100 cm of the soil surface. -1 Hyposalic (ws): having an ECe of 4 dS m or more at 25 °C in some layer within 100 cm of the soil surface. Sapric (sa): having, after rubbing, less than one-sixth (by volume) of the organic material consisting of recognizable plant tissue within 100 cm of the soil surface (in Histosols only). Silandic (sn): having one or more layers, cumulatively 30 15 cm or more thick, with andic properties and an acid oxalate (pH 3) extractable silica (Siox) content of 0.6 percent or more, or an Alpy to Alox ratio of less than 0.5 within 100 cm of the soil surface (in Andosols only). Thaptosilandic (snb): having one or more buried layers, cumulatively 30 15 cm or more thick, with andic properties and an acid oxalate (pH 3) extractable silica (Siox) content of 0.6 percent or more, or an Alpy to Alox ratio of less than 0.5 within 100 cm of the soil surface. Siltic (sl): having a texture of silt, silt loam, silty clay loam or silty clay in a layer, 30 cm or more thick, within 100 cm of the soil surface.
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Endosiltic (sln): having a texture of silt, silt loam, silty clay loam or silty clay in a layer, 30 cm or more thick, within 50 and 100 cm of the soil surface. Episiltic (slp): having a texture of silt, silt loam, silty clay loam or silty clay in a layer, 30 cm or more thick, within 50 cm of the soil surface. Skeletic (sk): having 40 percent or more (by volume) gravel or other coarse fragments averaged over a depth of 100 cm from the soil surface or to continuous rock or a cemented or indurated layer, whichever is shallower. Endoskeletic (skn): having 40 percent or more (by volume) gravel or other coarse fragments averaged over a depth between 50 and 100 cm from the soil surface. Episkeletic (skp): having 40 percent or more (by volume) gravel or other coarse fragments averaged over a depth of 50 cm from the soil surface. Sodic (so): having 15 percent or more exchangeable Na plus Mg on the exchange complex within 50 cm of the soil surface throughout. Endosodic (son): having 15 percent or more exchangeable Na plus Mg on the exchange complex between 50 and 100 cm from the soil surface throughout. Hyposodic (sow): having 6 percent or more exchangeable Na on the exchange complex in a layer, 20 cm or more thick, within 100 cm of the soil surface. Solodic (sc): having a layer, 15 cm or more thick within 100 cm of the soil surface, with the columnar or prismatic structure of the natric horizon, but lacking its sodium saturation requirements. Sombric (sm): having a sombric horizon starting within 150 cm of the soil surface. Spodic (sd): having a spodic horizon starting within 200 cm of the mineral soil surface. Spolic (sp): having a layer, 20 cm or more thick within 100 cm of the soil surface, with 20 percent or more (by volume, by weighted average) artefacts containing 35 percent or more (by volume) of industrial waste (mine spoil, dredgings, rubble, etc.) (in Technosols only). Stagnic (st): having within 100 cm of the mineral soil surface in some parts reducing conditions for some time during the year and in 25 percent or more of the soil volume, single or in combination, a stagnic colour pattern or an albic horizon. Endostagnic (stn): having between 50 and 100 cm from the mineral soil surface in some parts reducing conditions for some time during the year and in 25 percent or more of the soil volume, single or in combination, a stagnic colour pattern or an albic horizon. Epistagnic (stn): having within 50 cm of the mineral soil surface in some parts reducing conditions for some time during the year and in 25 percent or more of the soil volume, single or in combination, a stagnic colour pattern or an albic horizon. Subaquatic (sq): being permanently submerged under water not deeper than 200 cm (in Fluvisols only). 2- - Sulphatic (su): having a salic horizon with a soil solution (1:1 in water) with [SO4 ] >> [HCO3 ] > [Cl-] (in Solonchaks only). Takyric (ty): having a takyric horizon. Technic (te): having 10 percent or more (by volume, by weighted average) artefacts in the upper 100 cm from the soil surface or to continuous rock or a cemented or indurated layer, whichever is shallower. Tephric (tf): having tephric material to a depth of 30 cm or more from the soil surface or to continuous rock, whichever is shallower. Terric (tr): having a terric horizon. Thaptandic (ba): see Andic. Thaptovitric (bv): see Vitric. Thionic (ti): having a thionic horizon or a layer with sulphidic material, 15 cm or more thick, starting within 100 cm of the soil surface. Hyperthionic (tih): having a thionic horizon starting within 100 cm of the soil surface and having a pH (1:1 in water) less than 3.5.
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Orthothionic (tio): having a thionic horizon starting within 100 cm of the soil surface and having a pH (1:1 in water) between 3.5 and 4.0. Protothionic (tip): having a layer with sulphidic material, 15 cm or more thick, starting within 100 cm of the soil surface. Thixotropic (tp): having in some layer within 50 cm of the soil surface material that changes, under pressure or by rubbing, from a plastic solid into a liquefied stage and back into the solid condition. Tidalic (td): being flooded by tidewater but not covered by water at mean low tide. Toxic (tx): having in some layer within 50 cm of the soil surface toxic concentrations of organic or inorganic substances other than ions of Al, Fe, Na, Ca and Mg. Anthrotoxic (atx): having in some layer within 50 cm of the soil surface sufficiently high and persistent concentrations of organic or inorganic substances to markedly affect the health of humans who come in regular contact with the soil. Ecotoxic (etx): having in some layer within 50 cm of the soil surface sufficiently high and persistent concentrations of organic or inorganic substances to markedly affect soil ecology, in particular the populations of the mesofauna. Phytotoxic (ptx): having in some layer within 50 cm of the soil surface sufficiently high or low concentrations of ions other than Al, Fe, Na, Ca and Mg, to markedly affect plant growth. Zootoxic (ztx): having in some layer within 50 cm of the soil surface sufficiently high and persistent concentrations of organic or inorganic substances to markedly affect the health of animals, including humans, that ingest plants grown on these soils. Transportic (tn): having at the surface a layer, 30 cm or more thick, with solid or liquid material that has been moved from a source area outside the immediate vicinity of the soil by intentional human activity, usually with the aid of machinery, and without substantial reworking or displacement by natural forces. Turbic (tu): having cryoturbation features (mixed material, disrupted soil horizons, involutions, organic intrusions, frost heave, separation of coarse from fine materials, cracks or patterned ground) at the soil surface or above a cryic horizon and within 100 cm of the soil surface. Umbric (um): having an umbric horizon. Umbriglossic (ug): see Glossic. Urbic (ub): having a layer, 20 cm or more thick within 100 cm of the soil surface, with 20 percent or more (by volume, by weighted average) artefacts containing 35 percent or more (by volume) of rubble and refuse of human settlements (in Technosols only). Vermic (vm): having 50 percent or more (by volume, by weighted average) of worm holes, casts, or filled animal burrows in the upper 100 cm of the soil or to continuous rock or a cemented or indurated layer, whichever is shallower. Vertic (vr): having a vertic horizon or vertic properties starting within 100 cm of the soil surface. Vetic (vt): having an ECEC (sum of exchangeable bases plus exchangeable acidity in 1 M KCl) -1 of less than 6 cmolc kg clay in some subsurface layer within 100 cm of the soil surface. Vitric (vi): having within 100 cm of the soil surface one or more layers with andic or vitric properties with a combined thickness of 30 cm or more (in Cambisols: 15 cm or more), of which 15, cumulatively 30 cm or more thick, with have vitric properties, within 100 cm of the soil surface. Thaptovitric (bv): having within 100 cm of the soil surface one or more buried layers with andic or vitric properties with a combined thickness of 30 cm or more (in Cambisols: 15 cm or more), of which 15, cumulatively 30 cm or more thick, with have vitric properties, within 100 cm of the soil surface. Voronic (vo): having a voronic horizon (in Chernozems only).
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Xanthic (xa): having a ferralic horizon that has in a subhorizon, 30 cm or more thick within 150 cm of the soil surface, a Munsell hue of 7.5 YR or yellower and a value, moist, of 4 or more and a chroma, moist, of 5 or more. Yermic (ye): having a yermic horizon, including a desert pavement. Nudiyermic (yes): having a yermic horizon without a desert pavement.
SPECIFIERS
The following specifiers may be used to indicate depth of occurrence, or to express the intensity of soil characteristics. Their code is always added after the qualifier code. The specifiers are combined with other elements into one word, e.g. Endoskeletic. A triple combination, e.g. Epihyperdystric, is allowed. Bathy (..d): horizon, property or material starting the criteria of the qualifier are fulfilled for the required thickness somewhere between 100 and 200 cm from the soil surface. Cumuli (..c): having a repetitive accumulation of material with a cumulative thickness of 50 cm or more at the soil surface (e.g. cumulinovic and cumulimollic). Endo (..n): the criteria of the qualifier are fulfilled for the required thickness somewhere horizon, property or material starting between 50 and 100 cm from the soil surface. Epi (..p): the criteria of the qualifier are fulfilled for the required thickness somewhere horizon, property or material starting within 50 cm of the soil surface. Hyper (..h): having a strong expression of certain features. Hypo (..w): having a weak expression of certain features. Ortho (..o): having a typical expression of certain features (typical in the sense that no further or meaningful characterization is made). Para (..r): having resemblance to certain features (e.g. Paralithic). Proto (..t): indicating a precondition or an early stage of development of certain features (e.g. Protothionic). Thapto (..b): having a buried layer relating to diagnostic horizons, properties or materials horizon starting within 100 cm of the surface (given in combination with the buried diagnostic horizon, e.g. Thaptomollic).
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References
Asiamah, R.D. 2000. Plinthite and conditions for its hardening in agricultural soils in Ghana. Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. (Thesis) Blakemore, L.C., Searle, P.L. & Daly, B.K. 1981. Soil Bureau analytical methods. A method for chemical analysis of soils. NZ Soil Bureau Sci. Report 10A. DSIRO. Bridges, E.M. 1997. World soils. 3rd edition. Cambridge, UK, Cambridge University Press. Buivydaité, V.V., Vaičys, M., Juodis, J. & Motuzas, A. 2001. Lietuvos dirvožemių klasifikacija. Vilnius, Lievos mokslas. Burt, R., ed. 2004. Soil survey laboratory methods manual. Soil Survey Investigations Report No. 42, Version 4.0. Lincoln, USA, Natural Resources Conservation Service. Cooperative Research Group on Chinese Soil Taxonomy (CRGCST). 2001. Chinese soil taxonomy. Beijing and New York, USA, Science Press. CPCS. 1967. Classification des sols. Grignon, France, Ecole nationale supérieure agronomique. 87 pp. European Soil Bureau Network/European Commission. 2005. Soil atlas of Europe. Luxembourg, Office for Official Publications of the European Communities. FAO. 1966. Classification of Brazilian soils, by J. Bennema. Report to the Government of Brazil. FAO EPTA Report No. 2197. Rome. FAO. 1988. Soil map of the world. Revised legend, by FAO–UNESCO–ISRIC. World Soil Resources Report No. 60. Rome. FAO. 1994. World Reference Base for Soil Resources, by ISSS–ISRIC–FAO. Draft. Rome/Wageningen, Netherlands. FAO. 1998. World Reference Base for Soil Resources, by ISSS–ISRIC–FAO. World Soil Resources Report No. 84. Rome. FAO. 2001a. Lecture notes on the major soils of the world (with CD-ROM), by P. Driessen, J. Deckers, O. Spaargaren & F, Nachtergaele, eds. World Soil Resources Report No. 94. Rome. FAO. 2001b. Major soils of the world. Land and Water Digital Media Series No. 19. Rome. FAO. 2003. Properties and management of soils of the tropics. Land and Water Digital Media Series No. 24. Rome. FAO. 2005. Properties and management of drylands. Land and Water Digital Media Series No. 31. Rome. FAO. 2006. Guidelines for soil description. 4th edition. Rome. FAO–UNESCO. 1971–1981. Soil map of the world 1:5 000 000. 10 Volumes. Paris, UNESCO. Fieldes, M. & Perrott, K.W. 1966. The nature of allophane soils: 3. Rapid field and laboratory test for allophane. N. Z. J. Sci., 9: 623–629. Gong, Z., Zhang, X., Luo, G., Shen, H. & Spaargaren, O.C. 1997. Extractable phosphorus in soils with a fimic epipedon. Geoderma, 75: 289–296. Hewitt, A.E. 1992. New Zealand soil classification. DSIR Land Resources Scientific Report 19. Lower Hutt. Ito, T., Shoji, S., Shirato, Y. & Ono, E. 1991. Differentiation of a spodic horizon from a buried A horizon. Soil Sci. Soc. Am. J., 55: 438–442. Krogh, L. & Greve, M.H. 1999. Evaluation of World Reference Base for Soil Resources and FAO Soil Map of the World using nationwide grid soil data from Denmark. Soil Use & Man., 15(3):157–166. Nachtergaele, F. 2005. The “soils” to be classified in the World Reference Base for Soil Resources. Euras. Soil Sci., 38(Suppl. 1): 13–19. Němecěk, J. Macků, J., Vokoun, J., Vavříč, D. & Novák, P. 2001. Taxonomický klasifikační system půd České Republiky. Prague, ČZU. Olsen, S.R., Cole, C.V., Watanabe, F.S. & Dean, L.A. 1954. Estimation of available phosphorus by extraction with sodium bicarbonate. USDA Circ. 939. Washington, DC, United States Department of Agriculture. Poulenard, J. & Herbillon, A.J. 2000. Sur l’existence de trois catégories d’horizons de référence dans les Andosols. C. R. Acad. Sci. Paris, Sci. Terre & plan., 331: 651–657.
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Shishov, L.L., Tonkonogov, V.D., Lebedeva, I.I. & Gerasimova, M.I., eds. 2001. Russian soil classification system. Moscow, V.V. Dokuchaev Soil Science Institute. Shoji, S., Nanzyo, M., Dahlgren, R.A. & Quantin, P. 1996. Evaluation and proposed revisions of criteria for Andosols in the World Reference Base for Soil Resources. Soil Sci., 161(9): 604–615. Soil Survey Staff. 1999. Soil taxonomy. A basic system of soil classification for making and interpreting soil surveys. 2nd Edition. Agric. Handbook 436. Washington, DC, Natural Resources Conservation Service, United States Department of Agriculture. Soil Survey Staff. 2003. Keys to soil taxonomy. 9th Edition. Washington, DC, Natural Resources Conservation Service, United States Department of Agriculture. Sombroek, W.G. 1986. Identification and use of subtypes of the argillic horizon. In: Proceedings of the International Symposium on Red Soils, pp. 159–166, Nanjing, November 1983. Beijing, Institute of Soil Science, Academia Sinica, Science Press, and Amsterdam, Netherlands, Elsevier. Takahashi, T., Nanzyo, M. & Shoji, S. 2004. Proposed revisions to the diagnostic criteria for andic and vitric horizons and qualifiers of Andosols in the World Reference Base for Soil Resources. Soil Sci. Plant Nutr., 50 (3): 431–437. Van Reeuwijk, L.P. 2006. Procedures for soil analysis. 7th Edition. Technical Report 9. Wageningen, Netherlands, ISRIC – World Soil Information. Varghese, T. & Byju, G. 1993. Laterite soils. Their distribution, characteristics, classification and management. Technical Monograph 1. Thirivananthapuram, Sri Lanka, State Committee on Science, Technology and Environment. Zevenbergen, C., Bradley, J.P., van Reeuwijk, L.P., Shyam, A.K., Hjelmar, O. & Comans, R.N.J. 1999. Clay formation and metal fixation during weathering of coal fly ash. Env. Sci. & Tech., 33(19): 3405–3409. Zikeli, S., Kastler, M. & Jahn, R. 2005. Classification of Anthrosols with vitric/andic properties derived from lignite ash. Geoderma, 124: 253–265.
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Annex 1 Summary of analytical procedures for soil characterization
This annex provides summaries of recommended analytical procedures to be used for soil characterization for the World Reference Base for Soil Resources. Full descriptions can be found in Procedures for soil analysis (Van Reeuwijk, 2006) and the USDA Soil Survey Laboratory Methods Manual (Burt, 2004). 1. SAMPLE PREPARATION Samples are air-dried or, alternatively, oven-dried at a maximum of 40 °C. The fine earth fraction is obtained by sieving the dry sample with a 2-mm sieve. Clods not passing through the sieve are crushed (not ground) and sieved again. Gravel, rock fragments, etc. not passing through the sieve are treated separately. In special cases where air-drying causes unacceptable irreversible changes in certain soil properties (e.g. in peat and soils with andic properties), samples are kept and treated in the field- moist state. 2. MOISTURE CONTENT Calculation of results of soil analysis is done on the basis of oven-dry (105 °C) soil mass. 3. PARTICLE-SIZE ANALYSIS The mineral part of the soil is separated into various size fractions and the proportion of these fractions is determined. The determination comprises all material, i.e. including gravel and coarser material, but the procedure itself is applied to the fine earth (< 2 mm) only. The pre-treatment of the sample is aimed at complete dispersion of the primary particles. Therefore, cementing materials (usually of secondary origin) such as organic matter and calcium carbonate may have to be removed. In some cases, de-ferration also needs to be applied. However, depending on the aim of study, it may be fundamentally wrong to remove cementing materials. Thus, all pre-treatments are to be considered optional. However, for soil characterization purposes, removal of organic matter by H2O2 and of carbonates by HCl is routinely carried out. After this pre-treatment, the sample is shaken with a dispersing agent and sand is separated from clay and silt with a 63-µm sieve. The sand is fractionated by dry sieving, the clay and silt fractions are determined by the pipette method or, alternatively, by the hydrometer method. 4. WATER-DISPERSIBLE CLAY This is the clay content found when the sample is dispersed with water without any pre- treatment to remove cementing compounds and without use of a dispersing agent. The proportion of natural clay to total clay can be used as a structure stability indicator. 5. SOIL WATER RETENTION The water content is determined of soil samples that have been equilibrated with water at various suction (tension) values. For low suction values, undisturbed core samples are equilibrated on a silt and kaolin bath; for high suction values, disturbed samples are equilibrated in pressure plate extractors. The bulk density is calculated from the core sample mass.
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6. BULK DENSITY Soil bulk density is the mass per unit volume of soil. As bulk density changes with water content, the water status of the sample must be specified. Two different procedures can be used: • Undisturbed core samples. A metal cylinder of known volume is pressed into the soil. The moist sample mass is recorded. This may be the field-moist state or the state after equilibrating the sample at a specified water tension. The sample is then oven-dried and weighed again. The bulk density is the ratio of dry mass to volume at the determined water content and/or the specified water tension. • Coated clods. Field-occurring clods are coated with plastic lacquer (e.g. Saran dissolved in methyl ethyl ketone) to allow determination of underwater mass. This gives the volume of the clod. The moist sample mass is recorded. This may be the field-moist state or the state after equilibrating the clod at specified water suction. The sample is then oven-dried and weighed again. The bulk density is the ratio of dry mass to volume at the specified water suction. Note: The determination of bulk density is very sensitive to errors, particularly caused by non-representativeness of the samples (stones, cracks, roots, etc.). Therefore, determinations should always be made in triplicate. 7. COEFFICIENT OF LINEAR EXTENSIBILITY (COLE) The COLE gives an indication of the reversible shrink–swell capacity of a soil. It is calculated from the dry bulk density and the bulk density at 33 kPa water suction. The COLE value is expressed in centimetres per centimetre or as a percentage value. 8. PH The pH of the soil is potentiometrically measured in the supernatant suspension of a 1:2½ soil:liquid mixture. The liquid is either distilled water (pH-H2O) or a 1 M KCl solution (pH- KCl). In some cases definitions for classifcation specify a 1:1 soil:water ratio. 9. ORGANIC CARBON The Walkley–Black procedure is followed. This involves a wet combustion of the organic matter with a mixture of potassium dichromate and sulphuric acid at about 125 °C. The residual dichromate is titrated against ferrous sulphate. To compensate for incomplete destruction, an empirical correction factor of 1.3 is applied in the calculation of the result. Note: Other procedures, including carbon analysers (dry combustion) may also be used. In these cases a qualitative test for carbonates on effervescence with HCl is recommended and, if present, a correction for inorganic C (see Carbonate below) is required. 10. CARBONATE The rapid titration method by Piper (also called acid neutralization method) is used. The sample is treated with dilute HCl and the residual acid is titrated. The results are referred to as calcium carbonate equivalent as the dissolution is not selective for calcite and also other carbonates such as dolomite are dissolved to some extent. Note: Other procedures such as the Scheibler volumetric method may also be used. 11. GYPSUM Gypsum is dissolved by shaking the sample with water. It is then selectively precipitated from the extract by adding acetone. This precipitate is re-dissolved in water and the Ca concentration is determined as a measure for gypsum. 12. CATION EXCHANGE CAPACITY (CEC) AND EXCHANGEABLE BASES The ammonium acetate pH 7 method is used. The sample is percolated with ammonium acetate (pH 7) and the bases are measured in the percolate. The sample is subsequently percolated with sodium acetate (pH 7), the excess salt is then removed and the adsorbed Na exchanged by percolation with ammonium acetate (pH 7). The Na in this percolate is a measure for the CEC.
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Alternatively, after percolation with ammonium acetate, the sample can be washed free of excess salt, the whole sample distilled and the evolved ammonia determined. Percolation in tubes may also be replaced by shaking in flasks. Each extraction must be repeated three times and the three extracts should be combined for analysis. Note 1: Other procedures for CEC may be used provided the determination is done at pH 7. Note 2: In special cases where CEC is not a diagnostic criterion, e.g. saline and alkaline soils, the CEC may be determined at pH 8.2. Note 3: The base saturation of saline, calcareous and gypsiferous soils can be considered to be 100 percent. Note 4: Where low-activity clays are involved, the CEC of the organic matter has to be deducted. This can be done by the graphical method (FAO, 1966), or by analysing the CEC of the organic matter or the mineral colloids separately. 13. EXCHANGEABLE ACIDITY This is the acidity (H + Al) released upon exchange by an unbuffered 1 M KCl solution. It may also be designated actual acidity (as opposed to potential or extractable acidity). It is used to determine the so-called effective cation exchange capacity (ECEC) defined as: sum of bases + (H + Al), with bases being determined by ammonium acetate extraction. When the exchangeable acidity is substantial, the Al may be determined separately in the extract as it may be toxic to plants. Note: Because the contribution of H+ is often negligible, some laboratories only determine exchangeable Al. In that case, the ECEC is calculated as: sum of bases + Al. 14. EXTRACTABLE IRON, ALUMINIUM, MANGANESE AND SILICON These analyses comprise: • Free Fe, Al and Mn compounds in the soil extracted by a dithionite-citrate solution. (Both the Mehra and Jackson and Holmgren procedures may be used.) • Active, short-range-order or amorphous Fe, Al and silica Si compounds extracted by an acid oxalate solution. • Organically bound Fe and Al extracted by a pyrophosphate solution. 15. SALINITY Attributes associated with salinity in soils are determined in the saturation extract. The attributes include: pH, electrical conductivity (ECe), sodium adsorption ratio (SAR) and the cations and anions of the dissolved salts. These include Ca, Mg, Na, K, carbonate and bicarbonate, chloride, nitrate and sulphate. The SAR and the exchangeable sodium percentage (ESP) may be estimated from the concentrations of the dissolved cations. 16. PHOSPHATE RETENTION The Blakemore procedure is used. The sample is equilibrated with a phosphate solution at pH 4.6 and the proportion of phosphate withdrawn from solution is determined. 17. OPTICAL DENSITY OF OXALATE EXTRACT (ODOE) The sample is percolated or shaken with an acid ammonium oxalate solution. The optical density of the extract is measured at 430 nm wavelength. 18. MELANIC INDEX The sample is shaken with a 0.5 M NaOH solution and the absorbance of the extract is measured at 450 and 520 nm, respectively. The melanic index is obtained by dividing the absorbance at 450 nm by the absorbance at 520 nm. 19. MINERALOGICAL ANALYSIS OF THE SAND FRACTION After removal of cementing and coating materials, the sand is separated from the clay and silt by wet sieving. From the sand, the fraction 63–420 µm is separated by dry sieving. This fraction is divided into a heavy fraction and a light fraction with the aid of a high-density liquid: a
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solution of sodium polytungstate60 with a specific density of 2.85 kg dm-3. Of the heavy fraction, a microscopic slide is made; the light fraction is stained selectively for microscopic identification of feldspars and quartz. Volcanic glass can usually be recognized as isotropic grains with vesicles. 20. X-RAY DIFFRACTOMETRY The clay fraction is separated from the fine earth and deposited in an oriented fashion on glass slides or porous ceramic plates to be analysed on an X-ray diffractometer. Unoriented powder specimens of clay and other fractions are analysed on the same apparatus or with a Guinier X-ray camera (photographs).
60 Bromoform can also be used as high density liquid but its use is discouraged because of its highly toxic vapour.
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Annex 2 Recommended codes for the Reference Soil Groups, qualifiers and specifiers
Reference Soil Groups Acrisol AC Chernozem CH Kastanozem KS Podzol PZ Albeluvisol AB Cryosol CR Leptosol LP Regosol RG Alisol AL Durisol DU Lixisol LX Solonchak SC Andosol AN Ferralsol FR Luvisol LV Solonetz SN Anthrosol AT Fluvisol FL Nitisol NT Stagnosol ST Arenosol AR Gleysol GL Phaeozem PH Technosol TC Calcisol CL Gypsisol GY Planosol PL Umbrisol UM Cambisol CM Histosol HS Plinthosol PT Vertisol VR Qualifiers Abruptic ap Ferralic fl Irragric ir Reductaquic ra Aceric ae Ferric fr Lamellic ll Reductic rd Acric ac Fibric fi Laxic la Regic rg Albic ab Floatic ft Leptic le Rendzic rz Alcalic ax Fluvic fv Lignic lg Rheic rh Alic al Folic fo Limnic lm Rhodic ro Aluandic aa Fractipetric fp Linic lc Rubic ru Alumic au Fractiplinthic fa Lithic li Ruptic rp Andic an Fragic fg Lixic lx Rustic rs Anthraquic aq Fulvic fu Luvic lv Salic sz Anthric am Garbic ga Magnesic mg Sapric sa Arenic ar Gelic ge Manganiferric mf Silandic sn Aric ai Gelistagnic gt Mazic mz Siltic sl Aridic ad Geric gr Melanic ml Skeletic sk Arzic az Gibbsic gi Mesotrophic ms Sodic so Brunic br Glacic gc Mollic mo Solodic sc Calcaric ca Gleyic gl Molliglossic mi Sombric sm Calcic cc Glossalbic gb Natric na Spodic sd Cambic cm Glossic gs Nitic ni Spolic sp Carbic cb Greyic gz Novic nv Stagnic st Carbonatic cn Grumic gm Nudiargic na Sulphatic su Chloridic cl Gypsic gy Nudilithic nt Takyric ty Chromic cr Gypsiric gp Ombric om Technic te Clayic ce Haplic ha Ornithic oc Tephric tf Colluvic co Hemic hm Ortsteinic os Terric tr Cryic cy Histic hi Oxyaquic oa Thaptandic ba Cutanic ct Hortic ht Pachic ph Thaptovitric bv Densic dn Humic hu Pellic pe Thionic ti Drainic dr Hydragric hg Petric pt Thixotropic tp Duric du Hydric hy Petrocalcic pc Tidalic td Dystric dy Hydrophobic hf Petroduric pd Toxic tx Ekranic ek Hyperalbic hab Petrogleyic py Transportic tn Endoduric nd Hyperalic hl Petrogypsic pg Turbic tu Endodystric ny Hypercalcic hc Petroplinthic pp Umbric um Endoeutric ne Hyperdystric hd Petrosalic ps Umbriglossic ug Endofluvic nf Hypereutric he Pisocalcic cp Urbic ub Endogleyic ng Hypergypsic hp Pisoplinthic px Vermic vm Endoleptic nl Hyperochric ho Placic pi Vertic vr Endosalic ns Hypersalic hs Plaggic pa Vetic vt Entic et Hyperskeletic hk Plinthic pl Vitric vi Epidystric ed Hypocalcic wc Posic po Voronic vo Epieutric ee Hypogypsic wg Profondic pf Xanthic xa Epileptic el Hypoluvic wl Protic pr Yermic ye Episalic ea Hyposalic ws Puffic pu Escalic ec Hyposodic wn Eutric eu Eutrosilic es Specifiers Bathy ..d Epi ..p Ortho ..o Proto ..t Cumuli ..c Hyper ..h Para ..r Thapto ..b Endo ..n Hypo ..w
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459 UNITED NATIONS ECONOMIC COMMISSION FOR EUROPE CONVENTION ON LONG-RANGE TRANSBOUNDARY AIR POLLUTION International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests
MANUAL on methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests
Part IIIa
Sampling and Analysis of Soil
updated 06/2006 to be applied from 2007 on (as well as within the BioSoil project)
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CONTENTS
1. INTRODUCTION 7
2. SAMPLING 7 2.1. Georeferencing 7 2.2. Pedological Characterization of the Plots 7 2.3. Soil sampling 8 2.3.1. Allocation of Soil Sampling Sites 8 2.3.2. Sampling Time 8 2.3.3. Sampled Layers 8 2.3.4. Number of Samples and Sample Size 13 2.4. Conservation and Preparation of Samples 14
3. PHYSICAL AND CHEMICAL CHARACTERIZATION 15 3.1. Physical Characterization of the Organic Layer 15 3.1.1. Amount of Organic Layer 15 3.2. Physical Characterization of the Mineral Layer 15 3.2.1. Particle Size Distribution 15 3.2.2. Bulk Density of the total mineral soil 16 3.2.3. Coarse Fragments 17 3.2.4. Combined approach to estimate bulk density, coarse fragments and fine 17 earth stock 3.3. Chemical Characterization of Collected Samples 18 3.3.1. Selected Key Soil Parameters for the Level I and II Survey 18 3.3.2. Reference analytical methods 20
4. QUALITY ASSURANCE AND QUALITY CONTROL 22 4.1. Objectives 22 4.2. Starting points 22 4.3. Principles 22 4.4. Reference materials 22 4.4.1. Preparation of Local Reference Material 23 4.4.2. Initiation of Local Reference Material 23 4.4.3. Implementation of the Local Reference Material 23 4.4.4. Basic principles for use of the Shewhart control chart 24 4.4.5. Translating the results of the repeated sampling of Local Reference 24 Material into QA/QC 4.5. Co-operation with neighbouring laboratories 25 4.6. Submission of information on quality to European Level 25
5. DATA REPORTING 25
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6. REFERENCES 26
ANNEX 1: METHODS FOR SOIL ANALYSIS 27 SA01: Pre-treatment of Samples 29 SA02: Determination of Soil Moisture Content 33 SA03: Determination of Particle Size Distribution 37 SA04: Determination of Bulk Density 45 SA05: Determination of Coarse Fragments 55 SA06: Determination of Soil pH 61 SA07: Determination of Carbonate Content 65 SA08: Determination of Organic Carbon Content 69 SA09: Determination of Total Nitrogen Content 73 SA10: Determination of Exchangeable Cations, free H+ and free acidity 81 SA11: Aqua Regia Extractant Determinations 87 SA12: Determination of Total Elements 93 SA13: Acid Oxalate Extractable Fe and Al 101
ANNEX 2: FORMS 105 Form 4a – Contents of reduced plot file 107 Form 4b – Contents of datafile with soil analysis information Level I (Mandatory and 109 Optional) – To be used in the EU Forest Focus BioSoil demonstration project Form 4c – Contents of datafile with soil analysis information Level II (Mandatory) – To 114 be used in the EU Forest Focus BioSoil demonstration project
ANNEX 3: EXPLANATORY ITEMS 117
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Elaborated by: Expert Panel on Soil Forest Soil Co-ordinating Centre, Research Institute for Nature and Forest, Belgium
With the financial support of the Regulation (EC) N° 2152/2003 of the European Parliament and of the Council of 17 November 2003 concerning monitoring of Forests and Environmental Interactions in the Community (Forest Focus)
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1. Introduction
The present part of the manual outlines the sampling, analysis and reporting procedures for a set of soil parameters.
The purpose of the large-scale representative soil survey (Level I) is first of all the assessment of basic information on the chemical soil status and its changes over time, and secondly the assessment of soil properties which determine the forest soil’s sensitivity to air pollution. Besides providing soil data for the study of atmospheric deposition effects at the broader scale, the soil survey will serve other purposes, as studies related to climate change (e.g. inventory of carbon storage) and sustainable forest management (e.g. in addition to acidification status, also nitrogen studies and nutrient imbalances).
The intensive soil studies are conducted in selected areas on permanent plots (Level II) where other measurements for the analysis of the forest ecosystem are concentrated. The objectives of the special forest ecosystem analysis are the verification of hypotheses and in-depth analyses of damage mechanisms and the derivation of fundamental knowledge of forecasting future developments.
A third major objective of the large-scale representative soil survey (Level I) is to allow the evaluation of the (quality of) forest soils on a European scale. For the sake of data comparability between countries, a prime prerequisite is that the same methods for soil sampling and analysis are used throughout the network. As such, analytical results obtained by national methods, different from those described in this manual, cannot directly be compared with analytical results obtained by the international reference methods in this manual. Notwithstanding, the participating countries are encouraged to make efforts (where necessary and possible) to allow the comparison of the data obtained in the first survey with those of future surveys.
2. Sampling
2.1. Georeferencing
• One common datum, the World Geodetic System 1984 (WGS84) will be applied and no projection system (geographical lat/long coordinates in degrees, minutes, seconds). A GPS measurement (if technically possible) should be taken in the centre of the plot. • Information on the precision should be provided in the Data Accompanying Report Questionnaire (DAR-Q). • For Level I, the coordinates of crown condition survey plots should coincide.
2.2. Pedological Characterization of the plots
The pedological characterization: • Is mandatory for Level I and Level II plots; • Should be a general characterization, including a detailed site description with information on soil parent material (See Annex 3 “Explanatory Items N° 16”) and at least one profile description according to the FAO guidelines (FAO, 1990a). The soils should then be classified according to the most recent official version of the World Reference Base of Soil Resources (WRB)- classification system. All qualifiers need to be reported. The DAR-Q will mention which official version of WRB (FAO et al. 1998, IUSS Working Group WRB 2006) has been used. • Has to be carried out only once before the start of the first sampling activities, given all necessary information to allow for soil classification according to WRB is available. • The described soil profile(s) should be located at a location which is representative for the dominant soil type in the actual sampling area. For Level II this should be in the buffer zone of the plot. updated 06/2006 466 8 IIIa Sampling and Analysis of Soil – Update 2006
• The analytical data for soil classification should be reported. • Includes the identification of the dominant humus form on the observation plot (See Annex 3 “Explanatory Items” N° 6) according to the adopted description and classification guidelines.
Note: In the framework of the EU Forest Focus Demonstration Project. BIOSOIL, FSCC developed Guidelines for Forest Soil Profile Description, adapted for optimal field observations which are partly based on the 4th edition of the Guidelines for Soil Profile Description and Classification (FAO, In Press). In the BioSoil project it is recommended to use these guidelines in stead of the above mentioned FAO guidelines of 1990.
2.3. Soil sampling
2.3.1. Allocation of Soil Sampling Sites Level I: • judgmental design; • sampling sites may be located within the plot area, but only if samples are collected from bores. Sites that should be avoided are areas around tree stems (1m) and animal holes, disturbances like wind-thrown trees and trails. A record of the places sampled should be kept, so that they will not be resampled at a later date.
Level II: • random design or systematic design with a random component; • sampling sites have to be located in the buffer zone of the plot; sites to be avoided: see Level I.
2.3.2. Sampling Time In order to reduce temporal variations, especially in the organic layer, sampling activities should be confined to periods with low biological activity, e.g. winter or dry season, based on expert judgement. However, the countries that participated in the first survey, have to carry out the sampling activities in the same period (season) as for the first survey. The sampling dates have to be reported in the reduced plot file (form 4a).
2.3.3. Sampled Layers
2.3.3.1. General
The organic layer at the soil surface, which may consist of one or more of the following organic horizons: litter (OL), fermentation horizon (OF) and/or humus (OH) in aerated organic layers and Hf, Hfs or Hs in water saturated organic layers, is sampled separately from the underlying mineral soil. Buried organic layers are sampled in the same way as mineral layers. Material discarded for the representative sample can be used to refill bore holes or pits.
2.3.3.2. Organic Layer Sampling
A distinction has to be made between an organic layer that is saturated (H) or not saturated (O) with water according to the FAO-definition (FAO 1990a). The thickness of the different horizons OL, OF and OH or Hf, Hfs and Hs, constituting the organic layer and as defined in Box 1, has to be measured and reported.
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Box 1: Definitions of the organic layers
Distinction between saturated (H) and aerated (O) organic layers
A distinction is made between the water saturated organic layers, designated as ‘H’, and the aerated organic materials indicated as ‘O’ (FAO, 1990a):
• Organic O-layers or horizons are dominated by organic material, consisting of undecomposed or partially decomposed litter, such as leaves, needles, twigs, mosses and lichens, which has accumulated on the soil surface; they may be on top of either mineral or organic soils. O horizons are not saturated with water for prolonged periods. The mineral fraction of such material is only a small percentage of the volume of the material and generally is much less than half of the weight. An O layer may be at the surface of a mineral soil or at any depth beneath the surface if it is buried. A horizon formed by illuviation of organic material into a mineral soil is not an O horizon, though some horizons formed in this manner contain much organic matter.
• Organic H-layers or horizons are dominated by organic material, formed from accumulations of undecomposed or partially decomposed organic material at the soil surface which may be under water. All H horizons are saturated with water for prolonged periods or were once saturated but are now artificially drained. An H horizon may be on top of mineral soils or at any depth beneath the surface if it is buried.
Distinction of fresh, partly -, and well decomposed horizons in the organic O-layers
A subdivision of the organic O-layers is made according to the following definitions (partly based on Jabiol et al., 2004):
OL-horizon (Litter, Förna): this organic horizon is characterised by an accumulation of mainly leaves/needles, twigs and woody materials (including bark), fruits etc. This sublayer is generally indicated as litter. It must be recognized that, while the litter is essentially unaltered, it is in some stage of decomposition from the moment it hits the floor and therefore it should be considered as part of the humus layer. There may be some fragmentation, but the plant species can still be identified. So most of the original biomass structures are easily discernible. Leaves and/or needles may be discoloured and slightly fragmented. Organic fine substance (in which the original organs are not recognisable with naked eye) amounts to less than 10 % by volume.
Note: this horizon is generally called the litter layer (Klinka et al., 1981, Green et al., 1993, Jabiol et al., 1995, Delecour, 1980).
OF-horizon (fragmented and/or altered) is a zone immediately below the litter layer. This organic horizon is characterised by an accumulation of partly decomposed (i.e. fragmented, bleached, spotted) organic matter derived mainly from leaves/needles, twigs and woody materials. The material is sufficiently well preserved to permit identification as being of plant origin (no identification of plant species).The proportion of organic fine substance is 10 % to 70 % by volume. Depending on humus form, decomposition is mainly accomplished by soil fauna (mull, moder) or cellulose-decomposing fungi. Slow decomposition is characterised by a partly decomposed matted layer, permeated by hyphae.
Note: this is the fragmented layer in non-saturated soils (Klinka et al., 1981, Green et al., 1993, Jabiol et al., 1995, Delecour, 1980)
OH-horizon (humus, humification): characterised by an accumulation of well-decomposed, amorphous organic matter. It is partially coprogenic, whereas the F horizon has not yet passed through the bodies of soil fauna. The humified H horizon is often not recognized as such because it can have friable crumb structure and may contain considerable amounts of mineral materials. It is therefore often misinterpreted and designated as the Ah horizon of the mineral soil and not as part of the forest floor as such. To qualify as organic horizon, it should fulfil the FAO requirement, as updated 06/2006 468 10 IIIa Sampling and Analysis of Soil – Update 2006
described above. The original structures and materials are not discernible. Organic fine substance amounts to more than 70 % by volume. The OH is either sharply delineated from the mineral soil where humification is dependent on fungal activity (mor) or partly incorporated into the mineral soil (moder).
Note: This horizon coincides with what is called the humus layer (Klinka et al., 1981, Green et al., 1993, Jabiol et al., 1995, Delecour, 1980)
Distinction of subhorizons in the organic H-layers (Englisch et al., 2005):
Hf horizon (fibric): consists largely of poorly decomposed plant residues (tissues recognizable at naked eye)
Note: this horizon coincides with what is classified as fibric (Klinka et al., 1981, Green et al., 1993) or fibrist (Delecour, 1980).
Hs horizon (sapric): consists largely of well decomposed plant residues
Note: This horizon coincides with what is classified as humic (Klinka et al., 1981, Green et al., 1993) or saprist (Delecour, 1980).
Hfs horizon: decomposition of plant residues is intermediate between Hf and Hs, consists of fragmentized and partly oxidized peat
Note: This horizon coincides with what is classified as mesic (Klinka et al., 1981, Green et al., 1993) or hemist layer in saturated soils;
The following two horizons can be seen as special cases of the Hs horizon:
Hz horizon (zoogenic): consists of largely well decomposed plant residues with high and well recognisable earthworm activity (casts)
Hsl horizon (limnic): consists of largely well decomposed plant residues with high mineral content under aquatic conditions.
The OL-horizon has to be sampled separately. The OH-horizon has to be sampled separately only if it is thicker than 1 cm; otherwise, it may be sampled together with the OF-horizon. Optionally, the individual horizons (OL, OF, OH) may be sampled and analysed separately.
Note: For the BioSoil project the OF and OH layer can be sampled together (OF -layer).
For the submission of data, these horizons are designated as OL, OF, OFH and OH for the aerated organic (O) layers and as Hf, Hs, Hfs for the saturated H-layers.
Separation of the mineral and the organic layer Care should be taken to correctly separate the organic layer from the mineral soil material. Separation will be done in the field, but will be checked in the laboratory, following the internationally accepted criteria (WRB definitions, see Box 2) to make a distinction between both layers.
Box 2: Definition of organic soil materials
Organic soil material (FAO et al., 1998) consists of organic debris which accumulates at the surface under either wet or dry conditions and in which the mineral component does not significantly influence the soil properties. updated 06/2006 469 IIIa Sampling and Analysis of Soil – Update2006 11
Diagnostic criteria. Organic soil material must have one of the two following:
1. if saturated with water for long periods (unless artificially drained), and excluding live roots, either: a. 18 percent organic carbon (30 percent organic matter) or more if the mineral fraction comprises 60 percent or more clay; or b. 12 percent organic carbon (20 percent organic matter) or more if the mineral fraction has no clay; or c. a proportional lower limit of organic carbon content between 12 and 18 percent if the clay content of the mineral fraction is between 0 and 60 percent; or
2. if never saturated with water for more than a few days, 20 percent or more organic carbon.
According to these criteria, organic carbon determination (which is mandatory for both Levels of the survey) has to be used to check whether the separation has been done correctly. If necessary, clay analysis is required to guarantee a proper separation. If the separation was not done correctly, a new sample has to be taken.
Sampling method A frame of 25 by 25 cm is recommended, but alternatives with a minimum total surface of 500 cm2 are acceptable; for mor humus, an auger with a diameter of 8 cm can be used.
Determination of the organic layer weight In the field, the total fresh weight of each layer (OL, OF, OH or H) has to be determined, preferably together with the thickness of each organic layer (OL, OF, OH or H) (see also § 3.1.1.). Of each layer a subsample is collected for determination of moisture content (weight %) in the lab. Based on the result of the moisture content, the total dry weight (kg/m2) of each layer can be calculated.
Note: For the BioSoil project the OF and OH layer can be sampled together (OFH layer).
2.3.3.3. Mineral Layer Sampling
Location Where possible, the organic and mineral soil should be sampled at exactly the same locations, i.e. sample the mineral soil underneath the organic layer that has already been removed for sampling.
Procedure Sampling should be done by fixed depth. The top of the mineral soil corresponds with the zero level for depth measurements.
Mineral soil layers are designated as ‘Mij’, where i is the first number of the upper depth limit and j is the first number of the lower depth limit (e.g. M01 corresponds to the 0-10 cm layer). Table 1 shows the layers that should be sampled.
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Table 1: Status of layers to be sampled in both levels Level I (1) Level II (1) Mandatory Optional Mandatory Optional 0-10 cm 0-5 cm 0-10 cm 0-5 cm 10-20 cm 5-10 cm 10-20 cm 5-10 cm 20-40 cm (2) 20-40 cm (3) 40-80 cm (2) 40-80 cm (3) 1 Note that the entire thickness of the predetermined depth should be sampled and not the central part of the layer only. 2 Optional, but recommended if big changes between topsoil and subsoil are to be expected 3 Only mandatory for a first assessment, not to be repeated (optional) for a second survey if all mandatory parameters were determined with the reference method, see also par. 3.3.1., key soil parameters
If the upper surface of an indurated horizon (e.g. parent rock) is above the lower limit of sampled soil (20 cm for Level I; 80 cm for Level II), the soil is to be sampled till the depth of the limiting horizon. For example, a M48 layer subsample taken at a location where the rock surface reaches up to 65 cm below the soil surface is composed of material from the mineral soil between 40 and 65 cm depth. The depth range of the upper limit of the indurated horizon is reported under ‘Observations’ in form 4b.
Sampling method Augering preferred but pits are allowed, especially in case of stony soils where augerings are impossible.
2.3.3.4. Sampling of peatlands
The sampling design is based on the WRB definition of Histosols (= peat soils) which is based on the 40 cm boundary. As long as the peatlayer is less than 40 cm the existing sampling design for mineral forest soils shall be applied (separate sampling of the organic layers and mineral soil according to the fixed depth layers). From the moment the peat is ≥ 40 cm, the peatlayer shall be sampled according to the PEATLAND SAMPLING DESIGN.
This means that the peatlayer is sampled at fixed depths, mandatory 0 – 10 and 10 – 20 cm and optionally at 20 – 40 and 40 – 80 cm. In the reporting forms a separate name for the peatlayers shall be used, namely H01, H12, H24 and H48 in the records for the organic layers. The list of parameters (mandatory and optional) follow the rules for the OF, OH or OFH layer.
If the conditions allow (lower water table), the mineral soil below the peat soil (> 40 cm) can be further sampled according to the standard depths (M01, M12, M24, M48).
2.3.3.5. Sampling for Bulk Density
For the determination of bulk density, the sampling scheme deviates from the one for the mineral layer sampling that is needed for the analyses of all other parameters. Per plot, five samples with a minimal volume of 100 cm3 have to be taken from the mineral topsoil (0-10 cm) of non-stony soils using the core or excavation method (Soil Analysis Method 4 in Annex 1). Determination of bulk density by measurement is mandatory for level II, but if this measurement has been done according to the reference methods for the first survey, it has not to be repeated. For Level I, bulk density is a mandatory parameter too, but it can be estimated using pedo-transfer functions (see also § 3.2.2). A typical example of a pedotransfer function is the Adams (1973) equation:
100 BD = %*72.1 OC − %*72.1100 OC + 244.0 MBD
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Where %OC is the percentage total organic carbon and MBD is the mineral bulk density (usually estimated at 1.33 kg/m3 or determined based on the ‘Mineral Bulk Density Chart’ developed by Rawls and Brakensiek, 1985 – See Table 2).
Table 2: Mineral Bulk Density Chart (Rawls and Brakensiek, 1985) sand clay % 10 20 30 40 50 60 70 80 90 100 10 1.4 1.2 1.25 1.27 1.4 1.52 1.58 1.69 1.65 1.53 20 1.4 1.25 1.35 1.45 1.53 1.6 1.67 1.72 30 1.4 1.3 1.4 1.5 1.57 1.63 1.68 40 1.4 1.35 1.44 1.55 1.61 1.68 50 1.4 1.35 1.44 1.53 1.62
If pedotransfer functions are used, regional calibration and validation are necessary. Information on how to determine the usefulness and predictive quality of bulk density PTFs for forest soils can be found in De Vos et al (2005).
2.3.4. Number of Samples and Sample Size
2.3.4.1. Number of Samples in Composite
Level I: For every layer, mandatory 5 subsamples have to be taken (a composite of 5 is allowed) (e.g. if taken with an auger >= 8 cm diameter), but more subsamples are required according to the variability of the site. Mandatory 1 composite sample has to be analysed and reported, more can be analysed optionally to determine the variability of the site. In case of very stony soils where sampling by auger is not possible, 1 composite of at least 3 subsamples can be accepted for the optional depth layers (M24 and M48) only.
Level II: For every layer, mandatory a MINIMUM of 24 subsamples has to be taken, to be combined in at least three composite samples (i.e. at least 3 composites of each 8 subsamples or 4 composite samples of each 6 subsamples). Mandatory at least 3 values have to be reported (1 from each composite), to obtain information on the sampling variability. The samples should be representative for the whole plot area. The distance between 2 sampling points should be at least 5 meter in order to avoid autocorrelation.
The subsamples have to be of equal weight, except for situations with a variable lower depth limit. In such a case (e.g. an indurated horizon within the depth range of the sampled layer), the weight of each subsample is function of the thickness of the actually sampled layer. In the above example (section 2.2.3.3 last part), the weight of the subsample taken should be a fraction equal to (65-40)/(80-40) of the normal weight.
2.3.4.2. Sample Size
The minimum weight of each representative sample should be large enough for all analyses (mandatory and optional parameters) and possible repetitions or reanalyses in time. It is also advisable to keep the sample in a storeroom. The ISO 11464 method (Soil quality – Pretreatment of samples for physico-chemical analysis) recommends a sample size of at least 500 g of fresh soil for each sample.
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2.4. Conservation and Preparation of Samples
Preparation of soil samples is based on the ISO 11464 method (Soil quality – pretreatment of samples for physico-chemical analysis). Collected samples should be transported to the laboratory as soon as possible and be air dried or dried at a temperature of 40 °C (ISO 11464, 1994). They can then be stored until analysis. To recalculate the analysis results on weight basis, the moisture content of the sample has to be determined by oven-drying the sample once at 105°C (ISO 11465, 1993).
Living macroscopic roots and all particles, mineral and organic, with a diameter larger than 2 mm, should be removed from the samples by dry sieving as a preparation for analysis. The particles not passing the 2-mm sieve are weighed separately for the determination of the coarse fragments content (required for bulk density). To guarantee a harmonised approach, samples should not be further milled or ground. For those analyses for which finely ground material is required [this is Carbonate Content (SA07), Total Organic Carbon (SA08), Total Nitrogen (SA09) and Total Elements (SA12] further milling or grounding is allowed.
The sample materials for storage should be kept without preservative under normal room conditions with minimal temperature and humidity fluctuations, shielded from incident light.
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3. Physical and Chemical Characterization
3.1. Physical Characterization of the Organic Layer
3.1.1. Amount of Organic Layer Parameter Determination of the weight of the organic layer (volume-dry weight, kg/m2). For method of soil moisture content, see Annex I SA02).
Method In the field, the total fresh weight of each layer (OL, OF and OH or Hf, Hsf, and Hs) has to be determined, preferably together with the thickness of each organic layer (OL, OF and OH or Hf, Hsf, and Hs) (see also § 2.2.3.2.). Of each layer a subsample is collected for determination of moisture content (weight %) in the lab. Based on the result of the moisture content, the total dry weight (kg/m2) of each layer can be calculated.
Note: For the BioSoil project the OF and OH layer can be sampled together (OFH layer).
3.2. Physical Characterization of the Mineral Layer
3.2.1. Particle Size Distribution Parameters to be determined The determination of the soil granulometry and classification according to the USDA-FAO textural classes (Figure 1) is mandatory for the mineral layers for Level II, only if not already determined for the first survey (no repetition required if this parameter was already measured).
For Level I, information on textural class for the mineral layers is mandatory too (though again only if not done in the first survey). However, for Level I an estimate based on the finger test in the field on 1 composite of each layer can be accepted for classifying the soil texture according to the USDA-FAO textural classes. In addition an estimate of the clay content is mandatory as well. Practical guidelines can be consulted in the Guidelines for Forest Soil Profile Description (Mikkelsen et al., 2006).
Relevance Texture is needed for the profile description and WRB classification (mandatory for both Levels). In addition texture, and in particular the clay content, is required for the determination of nutrient exchange ability of the soil (interpretation of other - mandatory - parameters).
Box 3: Definition of particle size classes
The particle size classes of the fine earth fraction (< 2 mm) are defined as follows (FAO, 1990a):
Clay < 2 μm Silt 2 – 63 μm Sand 63 – 2000 μm
Method Level I: finger test for estimation of soil texture classified according to USDA-FAO texture triangle (FAO, 1990a), and for estimation of the clay content (%). Optional: reference method as described for Level II. Level II: reference method as described in Soil Manual of ICP forests (Annex 1: SA03)
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Practicability Repetition of the determination of the granulometry is not required. For Level I, extra time and costs are minimised if estimated by finger test.
Figure 1: Textural classes according to USDA (1951) and adopted by FAO (FAO, 1990a)
3.2.2. Bulk Density of the total mineral soil Optional and mandatory parameters One value of bulk density has to be reported mandatory for the mineral topsoil (0-10 cm) of non-stony soils. For Level I, this value may be obtained either by estimation, pedotransfer functions or measurement. For Level II, the bulk density has to be measured. Determination of the bulk density of the deeper layers is optional for both Levels. No re-measurement is required if this parameter was determined according to the reference method for the first survey.
Methodology For measurement: five samples have to be taken with a minimal volume of 100 cm3 per plot and per layer. In addition, the determination of bulk density requires estimation of coarse fragments according to the USDA-FAO classes (FAO, 1990a). This can be measured or estimated in the soil profile. This estimation according to the fixed depths shall be done in addition to the normal profile description which follows the genetic layers.
Definition Bulk density is defined as the mass (weight) of a unit volume of oven dry soil. The volume includes both solids and pores. In mineral soils with no coarse fragment content the bulk density of the total mineral soil is equal to the bulk density of the fine earth.
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Relevance The physical arrangement of the soil components is important for determining the nutrient supply to plants and in calculation of stocks. In addition, bulk density has an indirect influence on the concentrations of air pollutants in the soil (Vanmechelen et al., 1997).
3.2.3. Coarse Fragments Report the amount of coarse fragments (boulders, stones and gravel with a diameter > 2mm) of the individual mineral layers in volume %. The abundance of coarse fragments can be measured in the laboratory, but is usually estimated during routine soil profile observations. In the case that very coarse materials are present (stones and boulders), the quantity of these materials has to be estimated in the field (e.g. method established in Finland, as described in Annex 1: SA05 or in Germany, see Annex1: SA04). The determination of coarse fragments is mandatory for the 0-10 cm mineral layer and optional for 10- 80 cm mineral layer in both Level I and Level II. In case of re-assessment (if this parameter was already measured according to the reference method in first survey) the parameter is optional. For Level I the parameter may be estimated, for Level II it must be measured using the methods described in Annex 1: SA05.
3.2.4. Combined approach to estimate bulk density, coarse fragments and fine earth stock in stony soils Relevance Recent investigations (Riek and Wolff, 2006) have revealed that the soil physical parameters (in this case bulk density and fine earth stock) can only be recorded with field methods at specific locations in an inadequate or scarcely reproducible manner. This applies to soils with a high content of coarse gravel (2 – 6 cm) and/or the presence of stones (6 – 20 cm) and boulders (> 20 cm). Because of their low volume, the core samplers normally used in forest monitoring are not able to representatively collect stones or large portions of coarse fragments in the field. In these cases, the excavation method may produce good results but it is probably too expensive, time-consuming and destructive in the framework of large-scale monitoring.
Methodology The combined approach can improve the determination of these parameters at locations with a high content of coarse gravel and/or the presence of stones and boulders and lead to a better approximation of the real coarse fragments content. In the case of a high content of coarse gravel and/or the presence of stones and boulders, the quantity of bulk density of both fine earth and coarse fragments has to be estimated / sampled in the field. Methods should be selected according to the prevailing conditions (i.e. coarse fragment content and size) at each individual sampling site. In the analysis each method or each combined method leads to the determination of (partially) different parameters which means that different calculation formulas are needed. A description of the different methods and/or combined methods, the related parameters and calculation methods are described in Annex SA04.
If the mineral soil contains no coarse fragments or the (estimated) coarse fragment portion is less than 5 % (case 1), then the bulk density of the fine earth (BDfe) is approximately equivalent to the bulk density of the total mineral soil (BDs) (see paragraph 3.2.2).
In case of mineral soils with a coarse fragment content of more than 5% which can be sampled with a core sampler or any other (representative) sampler with coarse fragments < 20 mm (case 2), a representative volume sampling with core sampler, root auger, AMS core sampler with liner or hollow stem auger is done. When calculating the bulk density of the fine earth, the volume of the coarse fragment content is subtracted from the total volume of the sampler and the mass of the coarse fragments subtracted from the mass of the fine earth referring to this volume.
In case the mineral soil cannot be representatively sampled with a core sampler or any other samples (coarse fragments > 20 mm) (case 3), there are two possibilities of taking the coarse fragments into
updated 06/2006 476 18 IIIa Sampling and Analysis of Soil – Update 2006 account. The amount of coarse fragments has to be estimated in the field or be determined by additional sampling with a shovel or a spade (representative volume sampling).
When representative volume sampling is not possible, sampling with mini-core samplers and estimation at the profile (coarse fragments > 60 mm) is required (case 4). The bulk density of the fine earth in the spaces between the coarse material [soil skeleton] is determined with a mini-core sampler. In addition, a disturbed spade /shovel sample is taken in order to determine factor f (correction factor for a possible coarse fragment portion in the mini-core sampler). Furthermore, the coarse fraction portion > 60 mm is estimated at the profile.
3.3. Chemical Characterization of Collected Samples
3.3.1. Selected Key Soil Parameters for the Level I and II Survey An overview of the key parameters to be measured is presented in Table 3. The key parameters CEC and Base Saturation will be calculated from the data reported, and as such do not have to be submitted and are not included in the table. Note that the minimum requirement for a number of the mandatory parameters, indicate that in the mineral layers below 20 cm the parameters should be measured once and not necessarily be re-measured a second time. Temporal changes are in the first place expected in the upper layers. Mandatory Level II parameters of the deeper layers (20-40 and 40-80 cm) that were already measured with the reference method for the first survey, do not have to be determined again. This means that if all the mandatory parameters of these deeper layers were assessed with the reference method, re-sampling of these layers is not needed.
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Table 3: Chemical and physical key soil parameters (1) Parameter Unit Decimals Level I Level II Organic Layer Mineral Layer Organic Layer Mineral Layer OL OF+OH, H- 0-10 cm 10-20 cm 20-40 cm OL OF+OH, 0-10 cm 10-20 cm 20-40 cm (3) layers (2) 40-80 cm H-layers (2) 40-80 cm (3) Physical soil parameter Organic layer weight kg/m2 2 O M - - - O M - - - Coarse fragments % 0 - - M (3), (4) O (3), (4) O - - M O (3), (4) O (3), (4) Bulk density of the fine earth kg/m3 0 - - M (3), (5), (6) O (4) O - - M (3), (5) O O Particle size distribution (FAO, 1990a) - - - - M (3), (7) M (3), (7) O - - M (3) M (3) M (3) Clay content % 0 - - M (7) M (7) O - - M M M Silt Content % 0 - - O O O - - M M M Sand Content % 0 - - O O O - - M M M Chemical soil parameter pH(CaCl2) - 1 - M M M O - M M M M Organic carbon g/kg 1 - M M M O - M M M O Total nitrogen g/kg 1 - M M M O - M M M O Carbonates g/kg 0 - M (8) M (9) M (9) O - M (8) M (9) M (9) O Aqua Regia extracted mg/kg 1 O M O O O O M O O - P, Ca, K, Mg, Mn Aqua Regia extracted mg/kg 1 O M M - - O M M - - Cu, Pb, Cd, Zn Aqua Regia extracted mg/kg 1 O O O - - O O O - - Al, Fe, Cr, Ni, S, Hg, Na Exchangeable Acidity cmol(+)/ 2 - M (10) M M O - M (10) M M M kg Exchangeable Cations: cmol(+)/ 2 - M (10) M M O - M (10) M M M Ca, Mg, K, Na, Al, Fe, Mn, H kg pH(H2O) - 2 - O O O O - O O O O Total Elements: mg/kg 1 ------O O O Ca, Mg, Na, K, Al, Fe, Mn Oxalate extractable Fe, Al mg/kg 1 - O O O O - O M M M 1 Abbreviations : M = mandatory parameter, O = optional parameter 2 If the OH - horizon > 1 cm, the OF - and the OH - horizons should be analysed separately and each value has to be reported 3 In case of a re-assessment (if the parameter was already measured according to the reference method for the first survey) , the measurement is optional 4 May be obtained by estimation or measurement 5 Mandatory only in non-stony soils 6 May be obtained by estimation, pedo-transfer function or measurement 7 May be obtained by finger test, consists of texture classified according to USDA-FAO texture triangle 8 Only mandatory if pH(CaCl2) > 5.5 9 Only mandatory if pH(CaCl2) > 6 10 In calcareous soil, the measurement of this parameter is optional
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Relevance The relevance of the key parameters is given in Table 4.
With regard to the nutrients, the amount extracted by aqua regia has been made mandatory for the OF+OH horizons and H layers of the organic layer and optional for the mineral topsoil. While from this extraction not the real total content is obtained, it is useful as an estimate of the nutrient stock. Extra costs and work are minimal as it can be measured from the same extraction to be made for the heavy metals (mandatory for both the OF+OH horizons, H-layers and the mineral topsoil). For the determination of the 'real' total amounts, more specialised material and skill are required. As these 'real' total contents are important for the calculation of weathering rates and critical loads, they have been made optional for Level II.
Note that the measurement of Carbonates is required also for the correction of the organic carbon content if the pH(CaCl2) > 5.5 in the organic and > 6 in the mineral layer.
For the determination of the pH, measurement on a CaCl2-extract is recommended. pH(H2O) has been made an optional parameter for reasons of comparability, as this is mostly used in literature.
Table 4: Relevance of the key parameters
Type of Key parameters Layer Relevance parameter
Carbon and Ctot, Ntot, (Carbonates) Organic Forest nutrition, atmospheric N deposition, nitrogen climate change Mineral Forest nutrition (0-20 cm), C- & N sinks Nutrients Total P, Ca, Mg, K, Mn Organic Atmospheric deposition of basic cations, stock of main nutrients Mineral Weathering rates, critical loads of acidity, stock of main nutrients Acidity, Exchange pH, Carbonates, CEC, BS, Organic characteristics Exchangeable cations, Exchangeable Acidity pH, Carbonates, CEC, BS, Mineral Buffering acid input Exchangeable cations, Exchangeable Acidity, Alox, Feox Heavy metals Pb, Cu, Zn, Cd Organic Atmospheric metal deposition Mineral Atmospheric metal deposition, calculation critical loads (0-20 cm), deficiency of oligo elements Physical soil Organic layer weight Organic parameters Calculation of stocks Bulk density of the fine earth (BDfe) Mineral and the coarse fragment content
Practicability Elements that require special equipment or particular skill to determine correctly have been made optional or were skipped altogether.
3.3.2. Reference analytical methods The analytical methods proposed as the reference methods for the 1st survey are proposed again for the second survey, though adapted to ISO methods. The full description of the reference methods is given in Annex 1.
Table 5 gives an overview of the reference methods. Note that the parameters are grouped according to the analysis method. As such it is made clear which elements can be measured in the same run, without additional costs and hardly extra work involved.
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Table 5: Overview of reference methods for the chemical parameters
Parameter Reference Analysis Method 1 Unit 2 Extractant Measurement method(s) 3
pH(CaCl2) 0.01 M CaCl2 pH-electrode
pH(H2O) H2O pH-electrode Total nitrogen - Dry Combustion or Modified Kjeldahl g/kg Organic carbon4 - Dry Combustion at ≥ 900 °C Carbonates HCl Calcimeter P Colorimetry mg/kg K, Ca Mg ICP AAS Mn Aqua Regia Heavy metals: Cu, Cd, Pb, Zn Other: Al, Fe, Cr, Ni, Na Hg Cold vapour AAS S ICP CNS - analyser 5 + Free Acidity (or sum of AC ) and free H 0.1 M BaCl2 titration to pH 7.8 or 'German' method (difference in pH cmol+/kg before and after extraction and model) Exchangeable Cations Al, Fe, Mn, - 0.1 M BaCl ICP, AAS K, Ca, Mg, Na 2 FES Reactive Fe and Al Acid oxalate AAS, ICP mg/kg Total Elements: Ca, Mg, Na, K, Al, Fe, Mn Method using HF or Lithium metaborate, that brings all mg/kg elements into solution 1 Full descriptions are given in Annex 2 Results have to be expressed on an oven dry basis 3 For the measurement of a number of parameters there are several alternatives for the equipment that can be used 4 Note that for organic carbon a correction has to be made for carbonates 5 Alternative for the titration of the exchangeable acidity is the sum of the exchangeable Al, Fe, Mn and H (=Acid Cations)
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4. Quality assurance, quality control
4.1. Objectives
The guidelines below are based on the guidelines for quality assurance and control in the field and in the laboratory, as dealt with in detail in the submanual on the Measurement of Deposition (Annex VI.4 Quality Assurance and Quality Control for Atmospheric Deposition Monitoring by E. Ulrich and R. Mosello). The guidelines are intended to be used by the laboratories working on the analysis of the soil samples of the various assessments of the Pan European Monitoring Programme. In this paragraph, the focus is put on the analysis of the soil samples. These guidelines should allow the laboratories to develop their own methods to control the quality of soil analysis and should improve comparability of analysed data over the Programme.
4.2. Starting points
Quality assurance and Quality Control (QA/QC) are national issues. The National Focal centre (NFC) is responsible to select an adequate laboratory, the laboratories are responsible for the QA/QC. Laboratories use the proper equipment and the reference methods for the digestion and chemical analysis of samples. The laboratories set up good methods to control the quality of the analysis carried out. Proof of the obtained quality is documented and submitted to European level. Laboratories apply local, national and international reference material to ensure the quality over time and comparability on (inter-)national level.
4.3. Principles
Repetitive analysis of reference materials is the basis of a good QA/QC programme. The repeated digestion/analysis over time of the same sample will provide insight in the random and systematic deviation from the average over time. When the mean stays the same over a longer period of time, no trend is taking place. The measured values allow the calculation of the standard deviation around this mean.
Mapping of the values of the repeated analysed samples will show trends in time. The standard deviation can be used to define the limits (e.g 2 x SD) outside where the encountered value is highly improbable. Values outside this range function therefore as a warning signal. It indicates that something different then 'normal' has taken place. There are many possible reasons and such a warning signal has to be followed by proper laboratory actions.
4.4. Reference materials
Reference materials come in various sorts and prices. International Reference Materials (IRM) are expensive and should be used only when really needed. In many cases the concentrations are not in the ranges encountered in the daily practices. National Reference Materials (NRM) are in many cases easier to get and often not so expensive as IRM. They are in most cases issued by national laboratories and very useful to ensure the quality over the laboratories within a country. Local Reference Materials (LRM) are (to be) prepared by the laboratory itself and can be easily prepared in large quantities, very cheaply. It can also be made in the correct concentration ranges for the more important parameters. Especially these LRM have a high importance for the QA/QC activities.
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4.4.1. Preparation of Local Reference Material Due to the nature of the soil samples and its two-step analysis LRM samples of both the solid phase (to control the quality of digestion) and the liquid phase (to control the quality of the chemical analysis) is needed. Solid phase LRM: Take several larger samples from a site (e.g L/H horizons, mineral soil: 0-10 cm and 20-40 cm). Dry all sampled material and homogenise the sample material to ensure a uniform mixed sample. Split or riffle the sample in several parts and store in cool and dry place. It may be useful to prepare several LRM-sets for the different soil types and concentration regimes in the country (e.g. a LRM for the samples of a clay soil in the coastal area with high concentration of sea salt versus a LRM on sandy soil in and inland situation). Liquid phases LRM: After digestion of larger part of the solid phase LRM, store the liquid LRM in a cool and dark place.
In general, no control of high concentrations is done, because the errors are higher the lower the concentration is. Often, higher concentrated solutions are diluted in order to reduce the concentration so that they fit into the ranges for which the analysers were calibrated.
The quantity of the LRM has to be large enough to be used for a longer period of time (preferably up to one year). The needed annual quantity will depend on the type of analytical equipment and method used by the laboratory. The sample should be stored in such conditions that no (or minimal) changes take place over time.
Note: a small standard deviation around the mean is very nice and an indicator of very accurate and precise work, but not the first objective of this QA/QC.
4.4.2. Initiation of Local Reference Material When the LRM-sample has been prepared, a test run has to be made. For this initiation the equipment has to be calibrated as good as possible. A number of replicates (e.g.5 repetition of the solid phase and 30 of the liquid phase) of the LRM is to be analysed plus at least one (but preferably more) samples of a NRM or even an IRM. All relevant parameters are analysed. From the results of the NRM and IRM the accuracy in absolute sense is determined for each parameter. The spread of the results of the LRM gives an indication on the SD. Naturally the smaller the SD, the better the results. The results of this first test-run should be treated according to the ISO standard 8258 (1991) (Shewhart control charts). The mean value of the parameter in the LRM is of less importance, but should be in the same range as the values of the real samples. From this point each parameter has a SD. This could result in an evaluation of the included parameters and the relevance of the analysis by the methods applied. When the SD is significant larger then the expected values the relevance to analyse the parameter is small. Other methods/equipment may have to be used to analyse the parameter within an acceptable range. This procedure is to be repeated whenever equipment is changed, important parts are replaced or when trends seem to have taken place over time. In the latter case the absolute values obtained from the NRM and IRM are of high importance.
4.4.3. Implementation of the Local Reference Material After the successful initiation of the LRM a systematic re-sampling of the LRM (liquid phase) takes place in every batch or series. Depending on the number of samples to be analysed and the methods and equipment used, this could be in the range of one LRM per 10 analysed real samples to 1:20. For the solid phase (digestion and analysis) this could be reduced to 1:100. The results of the repeated analysis of the LRM allow the evaluation of the stability of the method/equipment over time. It is therefore important that no changes take place in the LRM sample over time. It is therefore strongly recommended that every analysis of the LRM is mapped in a graph over time (see ISO 8258). The example in Figure 4 shows lines with the mean (10), the 1*SD (9 and 11) and 2*SD (8 and 12) are indicated as a result of the initiation of the LRM.
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12 11 10 9 8 7 6 30-Mar 31-Mar 01-Apr 02-Apr 03-Apr 04-Apr 05-Apr 06-Apr 07-Apr 08-Apr 09-Apr 10-Apr 11-Apr 12-Apr 13-Apr 14-Apr 15-Apr 16-Apr 17-Apr 18-Apr 19-Apr 20-Apr 21-Apr 22-Apr 23-Apr 24-Apr 25-Apr
Figure 4: Example of a control graph for medium chloride concentrations in countries near the sea (in mg/l) with the mean around 10 and a SD on 0.9. The dots are the daily means of the measured values of the LRM over time.
4.4.4. Basic principles for use of the Shewhart control chart Assuming that the concentrations in the LRM do not change and the methods/equipment remain the same, the spread of the measured values should be within the range of 1*SD (68%) and randomly distributed around the mean. These two requirements need to be tested every time a set of samples is processed. The graph visualises these things easily, but statistical calculation will be needed to calculate the probability of the occasion. This means that when measured values fall (far) outside the 1*SD lines a problem has occurred. Similarly when the mean value (of e.g. the last 10 values) is drifting away from the original mean, systematic changes are taking place. A check of methods/equipment has to be carried out. If the values fall out of the 2*SD range, the equipment must be checked entirely and re-calibrated. Further on, the whole series of samples having been analysed during the time when the 2*SD range was exceeded, has to be reanalysed.
4.4.5. Translating the results of the repeated sampling of Local Reference Material into QA/QC The mapping of the values of the repeated sampling of the LRM over time is a proof of consistent analysis. Evaluation of the results per parameter leads now to a quality statement per parameter. This statement is only valid for the concentration range of the concerned LRM. It is therefore recommended to use in very different concentration situations more LRM’s. In general, it is sufficient to use two sample concentrations, one for low concentrations and one for medium concentrations (e.g. for nitrogen 1 and 5 g/kg). Samples with higher concentrations are regularly diluted by the lab technicians in order to fit in the calibrated concentration range. Moreover, higher concentrations have a much smaller percentage of error/variation (reproducibility: 1-5%) than low concentrations (reproducibility: 5-10 %) or very low concentrations (reproducibility: 10-20%).
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Box 4: Definition of reproducibility
The analytical results are obtained by the same method, using the same LRM, but not at the same moment (sometimes with days or weeks of delay between two subsequent analyses) and sometimes by different persons in the laboratory. The percentage of reproducibility is the variation coefficient of the annual mean of one LRM.
4.5. Co-operation with neighbouring laboratories
As mentioned before, the NRM and IRM may not have concentrations in the right ranges. This makes the tests less valuable. On the other hand when well initiated LRM are available, these could be used in neighbouring labs as an additional NRM or IRM. The cost is of course minimal and at the same time regional coverage with good samples is achieved. In a further step of cooperation, the analysis of parameters for which special equipment is needed (e.g. low concentrations of heavy metals), could be concentrated in a limited number of labs. In many cases pooled samples can be used to further reduce costs.
4.6. Submission of information on quality to European Level
Besides the actual measured values of the samples, also information on the QA/QC will be requested at European Level. This information consists of: • Complete description of the methods applied in view of the QA/QC, using a fixed coding system, in the form of a Data Accompanying Report Questionnaire (DAR-Q) • Description of the complete procedures of handling of the sample, including information on storage and delay time; produce a flow chart of the way the samples go from the field till the end of the different determinations; this chart should show the flow in time and space • Shewhart control charts of the LRM for the various parameters (including the statistical analysis such as initial Mean and SD, differences of the mean over time, points of action/re- measurement/calibration and or re-initiation) • Calculation of the coefficient of variation (reproducibility, definition see above) for all LRM, depending on the concentration (for each concentration a CV has to be calculated).
5. Data reporting
The following rules apply: • Data will be reported separately for the H- and O-horizons and for the mineral soil. • For the organic layers reporting is done according to the OL-, OF-, OH-, OFH-, Hf, Hs, Hfs horizons or as described in Box 1 of this manual. • For the mineral soil reporting is done according to the defined mandatory depth layers. • For the peat layers, reporting is done according to the defined depth layers (Mandatory: H01, H12 and Optional: H24 or H48) and following the parameter list for the OF, OH and H-layers of the organic horizons.
Data shall be submitted using the forms in Annex 2.
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6. References
Adams W.A. 1973. The effect of organic matter and true densities of some uncultivated podzolic soils. Journal of Soil Science, 24, 10-17. Delecour F. 1980. Essai de classification pratique des humus. Pedologie XXX: 225-241. Gand, Belgique. De Vos, B., Van Meirvenne, M., Quataert, P., Deckers, J. and Muys, B. 2005. Predictive quality of pedotransfer functions for estimating bulk density of forest soils. Soil Sci. Soc. Am. J. 69: 500-510. Englisch M., Katsensteiner K., Jabiol B. Zanella A., de Waal R., Wresowar M. and the European Humus Research Group. 2005. An attempt to create a classification key for BioSoil. FAO. 1990a. Guidelines for soil description, 3rd (revised) edition. FAO. 1990b. FAO - Unesco Soil Map of the World. World Soil Resources Report 60. FAO, Rome, Italy. FAO, ISRIC, ISSS. 1998. World Reference Base for Soil Resources. World Soil Resources Report 84. FAO, Rome, Italy. Green R.N., Townbridge R.L. and Klinka K. 1993. Towards a taxonomic classification of humus forms. Forest Science, Monograph 29. Society of American Foresters. 50 pp. ISO 8258. Shewart control charts. International Organization for Standardization. Geneva, Switzerland. 29 p. ISO 11464. 1994. Soil Quality – Pretreatment of samples for physico-chemical analysis. International Organization for Standardization. Geneva, Switzerland. 9 p. ISO 11465. 1993. Soil Quality –Determination of dry matter and water content on a mass basis – Gravimetric method. International Organization for Standardization. Geneva, Switzerland. 9 p. IUSS Working Group WRB. 2006. World reference base for soil resources 2006. World Soil Resources Reports No. 103. FAO, Rome Jabiol B., Brêthes A., Ponge J.-F., Toutain F. and Brun J.J. 1995. L'Humus sous toutes ses formes. ENGREF - Nancy. 63 pp. Jabiol B., Zanella A., Englisch M., Hager H., Katsensteiner K, De Waal R.W. 2004. Towards an European Classification of Terrestrial Humus Forms. Paper presented at the EuroSoil Congress, 4-12 September 2004, Freiburg, Germany. Klinka K., Green R.N., Townbridge R.L. and Lowe L.E. 1981. Taxonomic classification of humus forms in ecosystems in British Columbia. First approximation. Prov. of British Columbia. Ministry of Forests. 53 pp. Le Maitre, R.W. (Ed.), Bateman, P., Dudek, A., Keller, J., Lameyre, J., Le Bas, M.J., Sabine, P.A., Schmid, R., SØrensen, Streickeisen, A., Woolley, A.R. and Zannettin, B. 1989. A Classification of Igneous Rocks and Glossary of Terms. Recommendations of the International Union of Geological Scineces Subcommission on the Systematics of Igneous Rocks. Blackwell Scientific Publications, Oxford. Mikkelsen, J. Cools, N., Langohr, R. 2006 Guidelines for Forest Soil Profile Description, adapted for optimal field observations within the framework of the EU Forest Focus Demonstration Project. BIOSOIL. Partly based on the 4th edition of the Guidelines for Soil Profile Description and Classification (FAO, In Press). Rawls W.J., Brakensiek, D.L. 1985. Prediction of soil water properties for hydrologic modeling, in Proceedings of Symposium on Watershed Management, ASCE, pp. 293-299. U.S. Dept. of Agriculture. Soil Conservation Service. Soil Survey Staff. 1951. Soil Survey Manual. U.S. Dept. of Agric. Handb. 18. U.S. Govt. Print. Off. Washington, DC. 503 pp., illus. Vanmechelen L., Groenemans R., Van Ranst E. 1997. Forest Soil Condition in Europe. Brussels and Geneva, 261 pp.
updated 06/2006 485 United Nations Economic Commission for Europe Convention on Long-range Transboundary Air Pollution
International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests)
MANUAL
on
methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests
Part X Sampling and Analysis of Soil
updated: 05/2010
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Prepared by: ICP Forests Forest Soil Co-ordinating Centre and the Expert Panel on Soil and Soil Solution (Nathalie Cools and Bruno de Vos)
Cools N, De Vos B, 2010: Sampling and Analysis of Soil. Manual Part X, 208 pp. In: Manual on methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests, UNECE, ICP Forests, Hamburg. ISBN: 978-3-926301-03-1. [http://www.icp-forests.org/Manual.htm] All rights reserved. Reproduction and dissemination of material in this information product for educational or other non-commercial purposes are authorized without any prior written permission from the copyright holders provided the source is fully acknowledged. Reproduction of material in this information product for resale or other commercial purposes is prohibited without written permission of the copyright holder. Application for such permission should be addressed to: vTI - Institute for World Forestry Leuschnerstrasse 91 21031 Hamburg, Germany [email protected]
Hamburg, 2010
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Contents
1. Introduction ...... 9
2. Scope and application...... 9
3. Objectives...... 10
4. Location of measurements and sampling...... 11
4.1 Sampling design at plot level ...... 11 4.1.1 Pedological characterization of the plot ...... 12 4.1.1.1 Allocation of the soil sampling sites...... 12 4.1.1.2 Sampling time ...... 12 4.1.1.3 Sampled layers ...... 12 4.1.1.4 Number of samples ...... 12 4.1.2 Soil sampling at fixed depths ...... 14 4.1.2.1 Allocation of soil sampling sites...... 14 4.1.2.2 Sampling time ...... 14 4.1.2.3 Sampled layers ...... 15 4.1.2.4 Number of samples ...... 16 4.1.3 Sampling at fixed depth for soil bulk density...... 16 4.1.3.1 Allocation of the soil sampling sites...... 16 4.1.3.2 Sampling time ...... 16 4.1.3.3 Sampled layers ...... 17 4.1.3.4 Number of samples ...... 17 4.1.4 Sampling for soil water measurements...... 17 4.1.4.1 Allocation of the soil sampling sites...... 17 4.1.4.2 Sampling time ...... 17 4.1.4.3 Sampled layers and number of samples...... 17 4.2 Sampling equipment...... 18 4.2.1 Pedological characterisation of the plot ...... 18 4.2.2 Soil sampling at fixed depths ...... 18 4.2.3 Sampling of undisturbed soil core cylinders ...... 18 4.3 Sample collection...... 19 4.3.1 Pedological characterisation and profile pit sampling ...... 19 4.3.2 Sampling at fixed depths...... 19
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4.3.2.1 Organic layer sampling...... 19 4.3.2.2 Mineral soil sampling ...... 20 4.3.2.3 Size of samples...... 20 4.3.3 Cores for bulk density and soil water retention measurements...... 20 4.3.4 Excavation method for sampling for bulk density...... 21 4.4 Sample storage and transport ...... 21 4.5 Long-term storage of soil samples...... 22
5. Measurements ...... 22
5.1 Physical characterization ...... 22 5.1.1 Amount of organic layer...... 22 5.1.2 Particle size distribution...... 22 5.1.3 Bulk density of the total mineral soil...... 24 5.1.4 Coarse fragments ...... 24 5.1.5 Combined approach to estimate bulk density of the fine earth and the content of coarse fragments...... 24 5.1.6 Determination of the soil water retention characteristic (SWRC)...... 25 5.2 Chemical characterization of collected samples...... 26 5.2.1 Selected key soil parameters for the Level I and II Survey...... 26 5.2.2 Reference analytical methods ...... 29 5.3 Data quality requirements ...... 30 5.3.1 Plausibility limits...... 30 5.3.2 Data completeness...... 31 5.3.3 Data quality objectives or tolerable limits...... 31 5.3.4 Data quality limits ...... 31
6. Data handling ...... 31
6.1 Data submission procedures and forms ...... 31 6.2 Data validation...... 32 6.3 Transmission to co-ordinating centres, with timetable and rules ...... 32 6.4 Data processing guidelines...... 32 6.4.1 Derived soil parameters...... 32 6.4.2 Data Classification...... 32 6.4.3 Clustering Soil Observation Plots...... 32 6.4.4 Statistical methods ...... 33 6.5 Data reporting...... 33
7. References...... 33
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Annex 1 ...... 35
Methods for Soil Analysis ...... 35
Soil Analysis Method 1 (SA01) Pre-treatment of Samples ...... 37 Soil Analysis Method 2 (SA02): Determination of Soil Moisture Content ...... 41 Soil Analysis Method 3 (SA03): Determination of Particle Size Distribution...... 45 Soil Analysis Method 4 (SA04): Determination of Bulk Density...... 53 Soil Analysis Method 5 (SA05): Determination of Coarse Fragments...... 61 Soil Analysis Method 6 (SA06): Determination of Soil pH...... 67 Soil Analysis Method 7 (SA07): Determination of Carbonate Content ...... 71 Soil Analysis Method 8 (SA08): Determination of Organic Carbon Content...... 75 Soil Analysis Method 9 (SA09): Determination of Total Nitrogen Content ...... 79 Soil Analysis Method 10 (SA10): Determination of Exchangeable Cations (Al, Ca, Fe, K, Mg, Mn, Na), Free H+ and Exchangeable Acidity...... 85 Soil Analysis Method 11 (SA11): Aqua Regia Extractant Determinations P, Ca, K, Mg, Mn, Cu, Pb, Cd, Zn, Al, Fe, Cr, Ni, S, Hg, Na...... 93 Soil Analysis Method 12 (SA12): Determination of Total Elements Ca, Mg, Na, K, Al, Fe, Mn ...... 99 Soil Analysis Method 13 (SA13). Determination of Acid Oxalate Extractable Fe and Al.... 107 Soil Analysis Method 14 (SA14): Determination of the Soil Water Retention Characteristic ...... 111
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1. Introduction
This Part of the Manual outlines the sampling, analysis and reporting procedures for the set of soil parameters measured in the ICP Forests programme. Investigating forest soils is important on both Level I and Level II plots of the monitoring scheme. The purpose of the large-scale soil survey (Level I) is first of all the assessment of basic information on the chemical soil status and its changes over time, and secondly the assessment of soil properties which determine the forest soil’s sensitivity to air pollution (e.g. acidification status). Besides providing soil data for the study of atmospheric deposition effects at the broader scale, the soil survey will serve other purposes, as supporting studies related to climate change (e.g. inventory of carbon storage) and sustainable forest management (e.g. nutrient and water balances studies). A third major objective of the large-scale representative soil survey (Level I) is to allow the evaluation of the forest soil condition across Europe. For the sake of data comparability among countries, a prerequisite is that the same methods for soil sampling and analysis are used throughout the network. As such, analytical results obtained by national methods, different from those described in this manual, cannot directly be compared with analytical results obtained by the international reference methods of this manual. Notwithstanding, the participating countries are encouraged to make efforts (where necessary and possible) to allow the comparison of the data obtained in the first survey with those of future surveys. The intensive soil studies are conducted on permanent plots (Level II) where other measurements and assessments for the analysis of the forest ecosystem are performed. Intensive soil measurements are essential in understanding the role of forest soils in cause-effect relationships and in ecosystem functions and services. The intensive soil study involves the soil characterisation, the evaluation of the soil condition and the study of the soil processes and dynamics on the long-term. Methods for the short-term soil dynamics are described in the Part XI on Soil Solution Collection and Analysis and partly in Part IX on Meteorological Measurements (soil temperature and soil water dynamics).
2. Scope and application
Soil analyses are relevant to many environmental applications such as studies on acidification, eutrophication, C stock assessment, nutrient fluxes, water balances, biodiversity assessments and impact of climate change. This Part presents all the soil related field and laboratory parameters that are required for these studies within the ICP Forests programme. Concerning the field observations and sampling, the aim is to provide a set of minimum requirements which need to be met to come to a harmonised approach. Related to the analyses in the laboratory, all laboratories have to use the reference methods, which mainly follow ISO standards. The relevance of the key soil parameters is given in Table 1. Table 2 provides an overview on the mandatory and optional soil surveys. An overview on the mandatory and optional parameters and depths of samplings is given in Table 11 for the set of soil physical and soil chemical parameters and in Table 7 and 9 for the soil moisture measurements.
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Table 1: Relevance of the key soil parameters Type of Key parameters Layer Relevance parameter
Carbon and Ctot, Ntot, (Carbonates) Organic Forest nutrition, atmospheric N nitrogen deposition, climate change Mineral Forest nutrition (0-20 cm), C- & N sinks Nutrients Total P, Ca, Mg, K, Mn Organic Atmospheric deposition of basic cations, stock of macronutrients Mineral Weathering rates, critical loads of acidity, stock of macronutrients Acidity, pH, Carbonates, CEC, BS, Organic Exchange Exchangeable cations, characteristics Exchangeable Acidity pH, Carbonates, CEC, BS, Mineral Buffering acid input, acidification Exchangeable cations, status Exchangeable Acidity, Alox, Feox Heavy metals Pb, Cu, Zn, Cd, Cr, Ni, Hg Organic Atmospheric metal deposition Mineral Atmospheric metal deposition, calculation critical loads (0-20 cm), deficiency of oligo elements Physical soil Particle size distribution and Mineral Profile description and soil parameters soil texture classification, estimation of plant available water, nutrient exchange capacity Organic layer mass Organic Calculation of stocks
Bulk density of the fine earth Mineral Calculation of stocks, nutrient (BDfe) and the coarse fragment supply to plants, index for content compaction Soil Water Retention Organic Water balance models, nutrient Characteristic (SWRC) Mineral fluxes, estimation of soil porosity
Table 2: Overview of soil survey at the Level I, II and the Level II core plots Soil survey Level I Level II Level II core Pedological characterisation Mandatory (once at installation of plot) Soil sampling at fixed depths Mandatory (every 10 - 20 years) * Soil sampling for bulk density at fixed depths Mandatory Sampling for measurement of SWRC Optional Optional Mandatory * Pan-European synchronisation within a period of 3 years is essential
3. Objectives
This manual is designed to provide a consistent methodology to collect high quality, harmonised and comparable forest soil data across Europe. This will allow (i) the proper characterization and description of the soil condition; and (ii) to monitor changes in soil properties periodically (e.g. on a 10 years basis). The soil survey comprises three main pillars (Table 2):
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1. Pedological characterisation. At the plot installation a detailed soil profile pit description complemented by sampling according to genetic horizons should lead to a detailed soil classification following the World Reference Base for Soil Resources (IUSS Working Group WRB, 2007a, 2007b). 2. Monitoring of the soil condition. Both the organic and the mineral soil layers are sampled and analysed in the laboratory at regular time intervals (e.g. every 10 years). For this purpose, composite samples are taken at fixed depth layers. 3. Determination of the soil water retention characteristic (SWRC). The assessment of the forest water budget is essential to study the nutrient fluxes in the forest ecosystem on the permanent monitoring plots. For the parameterisation of various water balance models meteorological data, stand characteristics and soil physical data are essential. For the validation of the models soil temperature, soil moisture and stand precipitation measurements are needed. To characterise the soil water retention, a series of undisturbed soil samples need to be taken and analysed in the laboratory. This survey is mandatory on all plots where water budgets are assessed.
4. Location of measurements and sampling
4.1 Sampling design at plot level Table 3 provides an overview of the sampling design on the Level I and Level II plots.
Table 3: Overview of sampling design on the Level I and Level II plots N° of soil N° of N° of soil Location of sampling samples Objective Sampling design sampling layers regards the plot area per layer points per point and point Pedological characterization Representative for dominant = N° of Level I Judgemental ≥1 ≥1 soil type within the plot area horizons = N° of Level II Buffer zone Judgemental ≥1 ≥1 horizons Soil sampling at fixed depth ≥ 5 (but on stony soils Sampling sites should be Level I Judgemental for optional 3 to 8 1 located within the plot area. depth layers ≥ 3) Sampling sites should be Random design or located within the plot area or systematic design Level II ≥24 5 to 8 1 if not feasible, in the buffer with a random zone of the plot. component. Sampling at fixed depth for soil bulk density Level I Not specified Not specified 0 to 5 0 to 5 0 to 1 Level II Not specified Not specified 5 3 to 5 1 Sampling for soil water measurements In vicinity of field Level II core Within the plot soil moisture 3 3 to 7 ≥1 probes
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4.1.1 Pedological characterization of the plot
4.1.1.1 Allocation of the soil sampling sites The pedological characterization: Is mandatory for Level I and Level II plots but has to be carried out only once; Includes a detailed profile characterisation with information on soil parent material and at least one profile description with characterisation by horizons according to the Field Guidelines for Forest Soil Profile Description (see Annex 2) which are partly based on the 4th edition of the Guidelines for Soil Profile Description and Classification (FAO, 2006). The soils should then be classified according to the most recent official version of the World Reference Base of Soil Resources (WRB)-classification system. It is recommended to report all qualifiers. In addition, the correct reference needs to be made to the applied WRB reference system (IUSS Working Group WRB 2006, 2007a, 2007b). An overview of the mandatory and optional parameters for the pedological characterisation is given in Table 4. Includes the identification of the dominant humus form on the observation plot according to the adopted description and classification guidelines (Zanella et al., 2009). The described soil profile(s) should be located at locations representative for the dominant soil type in the actual sampling area. For Level II this should be in the buffer zone of the plot. More detailed information on the location and orientation of the soil profile and on the required observations which need to be made while digging the profile are given in Annex 3.
4.1.1.2 Sampling time Has to be carried out only once to make sure that all necessary information is available for soil classification according to WRB. See Annex 2: Guidelines for forest soil description.
4.1.1.3 Sampled layers Each pedological characterisation needs to be accompanied by sampling of the identified horizons. Note that for the mineral horizon designations, the FAO (2006) definitions are applied whereas for the organic horizons the European horizon symbols (OL, OF and OH, Hf, Hfs and Hs) which are in use in forestry for many years (see Annex 7). The analytical data required for soil classification should be reported in the PFH-file.
4.1.1.4 Number of samples One sample for each identified horizon is sufficient. In case more than one sample for each horizon is analysed, the average value should be reported.
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Table 4: Overview of mandatory and optional parameters for the pedological characterisation of the plot on Level I and Level II Parameter Unit Decimals Mandatory /Optional Profile characterisation Coordinates of the profile pit +/-DDMMSS 0 M Date of profile description DDMMYY M Elevation of profile pit Metres asl 0 O WRB Reference Soil Group (see IUSS WG on Code M WRB, 2007a, 2007b) WRB qualifiers and specifiers (see IUSS WG on Code O WRB, 2007a, 2007b) Definition of diagnostic horizons, properties and Code O materials (see IUSS WG on WRB, 2007a, 2007b) Upper depth limit of diagnostic horizons, properties cm from mineral soil 0 O and materials surface WRB reference publication Code M Land use Code M Parent material Code M Mean highest and mean lowest groundwater table Code O(1) depth Type of water table Code O(1) Effective rooting depth in cm from mineral soil cm from mineral soil 0 M surface surface Rock depth in cm from the mineral soil surface cm from mineral soil 0 M surface Obstacle depth in cm from mineral soil surface cm from mineral soil 0 M surface
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Parameter Unit Decimals Mandatory /Optional Horizon characterisation Org. Min. Layer Layer Horizon number Integer M M Date laboratory analysis DDMMYY M M Horizon name (symbols for master horizon, Code M(2) M(2) subordinate symbol, indication of discontinuity, vertical subdivision) Upper and lower limit horizon cm from mineral soil 0 M M surface Horizon distinctness and topography Code O O Structure Code O M Moist and dry colour of the soil matrix Munsell colour code O M Textural class FAO (2006) code M Clay (0 – 2 micrometer fraction) % 1 O Silt (2 – 63 micrometer fraction) % 1 O Sand (63 – 2000 micrometer fraction) % 1 O Code coarse fragments Code based on vol % O O Coarse fragments weight % 0 O O Total Organic Carbon content g/kg 1 O O Total Nitrogen g/kg 1 O O Total Calcium Carbonate g/kg 0 O O Gypsum content g/kg 0 O O pH 2 O O Electrical conductivity dS.m-1 0 O O Exchangeable Ca, Mg, K, Na cmol(+)/kg 3 O O Cation Exchange Capacity cmol(+)/kg 2 O O Base Saturation % 0 O O Code Porosity Code O O Measured or Estimated Bulk Density kg/m3 0 O O Abundance classes of very fine, fine, medium and Code O(3) O(3) coarse roots 1 In hydromorphic soils, this parameter is mandatory 2 Master symbol is always mandatory. Subordinate symbol, indication of discontinuity, vertical subdivision only when it is defined. 3 Mandatory on Level II core plots
4.1.2 Soil sampling at fixed depths
4.1.2.1 Allocation of soil sampling sites Sites that should be avoided are areas around tree stems (1m) and animal holes, disturbances like wind-thrown trees and trails. A record of the places sampled should be kept.
4.1.2.2 Sampling time In order to reduce temporal variations, especially in the organic layer, sampling activities should be confined to periods with low biological activity, e.g. winter or dry season, based on expert judgement. However, the countries that participated in the first survey have to carry out the sampling activities in the same period (season) as for the first survey. The sampling dates have to be reported in the reduced plot file (*.PLS file).
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4.1.2.3 Sampled layers The organic layer at the soil surface is sampled separately from the underlying mineral soil. Buried organic layers are sampled in the same way as mineral layers. Care should be taken to correctly separate the organic layer from the mineral soil material. Separation will be done in the field, but will be checked in the laboratory, following the internationally accepted criteria (FAO 2006, see Annex 7) to make a distinction between both layers. According to these criteria, organic carbon determination (which is mandatory for both Levels of the survey) has to be used to check whether the separation has been done correctly. If the separation was not done correctly, a new sample has to be taken. Where possible, the organic and mineral soil should be sampled at exactly the same locations, i.e. sample the mineral soil where the organic layer has already been removed for sampling. A distinction has to be made between an organic layer that is saturated (H) or not saturated (O) with water according to the FAO-definition (FAO, 2006). The organic layer in aerated conditions may consist of one or more of the following organic subhorizons (Zanella et al. 2009; Zanella et al., in preparation): litter (OL), fragmentation horizon (OF) and/or humus (OH). In water saturated organic layers a distinction has to be made between Hf, Hfs or Hs horizon. Detailed definition and descriptions can be consulted in Annex 7. For the submission of data, these horizons are designated as OL, OF, OFH and OH for the aerated organic (O) layers and as Hf, Hs, Hfs for the saturated H-layers. The thickness of the different horizons has to be measured and reported. If OL-horizon is sampled, it should be sampled separately. The OH-horizon has to be sampled separately only if it is thicker than 1 cm; otherwise, it may be sampled together with the OF- horizon. Optionally, the individual horizons (OL, OF, OH) may be sampled and analysed separately. In the mineral soil, sampling should be done by fixed depth. The top of the mineral soil corresponds with the zero reference level for depth measurements. Mineral soil layers are designated as ‘Mij’, where i is the first number of the upper depth limit and j is the first number of the lower depth limit (e.g. M01 corresponds to the 0-10 cm layer). Table 5 shows the layers that should be sampled.
Table 5: Status of layers to be sampled in both levels Level I (1) Level II (1) Mandatory Optional Mandatory Optional OF+OH, H layer OL layer OF+OH, H layer OL layer 0-10 cm 0-5 cm 0-10 cm 0-5 cm 10-20 cm 5-10 cm 10-20 cm 5-10 cm 20-40 cm 40-80 cm (2) 20-40 cm 40-80 cm (3) 1 Note that the entire thickness of the predetermined depth should be sampled and not the central part of the layer only. 2 Optional, but recommended if big changes between topsoil and subsoil are to be expected 3 Only mandatory for a first assessment, not to be repeated (optional) for a second survey if all mandatory parameters were determined with the reference method, see also par. 5.2.1., key soil parameters If the upper surface of an indurated horizon (e.g. parent rock) is above the lower limit of sampled soil (40 cm for Level I; 80 cm for Level II), the soil is to be sampled till the depth of the limiting horizon. For example, a M48 layer subsample taken at a location where the rock surface reaches up to 65 cm below the soil surface is composed of material from the mineral soil between 40 and 65 cm depth. The depth range of the upper limit of the indurated horizon is reported under ‘Rock depth’or ‘Obstacle depth’ in the PRF file. Material discarded for the representative sample can be used to refill bore holes or pits. version 5/2010 15
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Sampling of peatlands The sampling design is based on the WRB definition of Histosols (= peat soils) which is based on the 40 cm boundary. As long as the peatlayer is less than 40 cm the existing sampling design for mineral forest soils shall be applied (separate sampling of the organic layers and mineral soil according to the fixed depth layers). From the moment the peat is ≥ 40 cm, the peatlayer shall be sampled according to the PEATLAND SAMPLING DESIGN. This means that the peatlayer is sampled at fixed depths, mandatory 0 – 10 and 10 – 20 cm and optionally at 20 – 40 and 40 – 80 cm. In the reporting forms a separate name for the peatlayers shall be used, namely H01, H12, H24 and H48 in the records for the organic layers. The list of parameters (mandatory and optional) follow the rules for the OF, OH or OFH layer. If the conditions allow (lower water table), the mineral soil below the peat soil (> 40 cm) can be further sampled till a depth of 80 cm (where the 0 cm reference is at the top of the peat layer). The standard sampling depths should be followed as much as possible.
4.1.2.4 Number of samples Level I: For every layer, mandatory 5 subsamples have to be taken (a composite of 5 is allowed) (e.g. if taken with an auger >= 8 cm diameter), but more subsamples are required according to the variability of the site. Mandatory 1 composite sample has to be analysed and reported, more can be analysed optionally to determine the variability of the site. In case of very stony soils where sampling by auger is not possible, 1 composite of at least 3 subsamples can be accepted for the optional depth layers (M24 and M48) only. Level II: For every layer, mandatory a MINIMUM of 24 subsamples has to be taken, to be combined in at least three composite samples (i.e. at least 3 composites of each 8 subsamples or 4 composite samples of each 6 subsamples). Each composite sample should be spatially clustered. Mandatory at least 3 values have to be reported (1 from each composite), to obtain information on the sampling variability among clusters (composites). The samples should be representative for the whole plot area. The distance between sampling clusters (composites) should be at least 5 meter in order to avoid autocorrelation. The subsamples have to be of equal mass, except for situations with a variable lower depth limit. In such a case (e.g. an indurated horizon within the depth range of the sampled layer), the mass of each subsample is function of the thickness of the actually sampled layer. In the above example (section 4.1.2.3. last part), the mass of the subsample taken should be a proportion equal to (65- 40)/(80-40) of the standard sample mass.
4.1.3 Sampling at fixed depth for soil bulk density
4.1.3.1 Allocation of the soil sampling sites Not yet specified except when done in association with soil water measurements (see 4.1.4.1). Determination of bulk density by measurement is mandatory for level II, but if this measurement has been done according to the reference methods for the first survey, it has not to be repeated. For Level I, bulk density is a mandatory parameter too, but it can be estimated using pedo-transfer functions. If pedotransfer functions are used, regional calibration and validation are necessary. Information on how to determine the usefulness and predictive quality of bulk density PTFs for forest soils can be found in De Vos et al. (2005).
4.1.3.2 Sampling time Not yet specified.
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4.1.3.3 Sampled layers The determination of the bulk density is mandatory on 3 depth layers (0-10 cm, 10-20 cm and 20- 40 cm) on non-stony soils and optional on the 4th depth layer (40-80 cm).
4.1.3.4 Number of samples Per plot, five samples with a minimal volume of 100 cm3 have to be taken.
4.1.4 Sampling for soil water measurements
4.1.4.1 Allocation of the soil sampling sites On each plot at least 3 profiles are sampled separately. The location of these profiles within the plot may be chosen freely, as long as their spatial design meets following requirements: The individual profiles are representative for the soil condition within the plot; The profiles are not located in one single profile pit (i.e. profiles are at least some meters apart); The profiles should be situated as close as possible to the location of the soil moisture measurement sensors; The exact coordinates of each profile location should be determined and kept for internal record.
4.1.4.2 Sampling time The samples should be taken when the soil is close to field capacity, which is often towards the end of the winter. Do not sample the soils when it is freezing. Ideally the undisturbed cores are taken at the time of the installation of the soil moisture probes to assure 1) minimal soil disturbance and 2) that the cores are taken in the same layer and horizon as the soil moisture sensors.
4.1.4.3 Sampled layers and number of samples At each location, adequate undisturbed soil sampling within the soil profile is done according to the sampling scheme in Table 6. At least one undisturbed core is taken within the fixed depth intervals 0 - 20, 20 - 40 and 40 - 80 cm, preferentially at the same depth as the soil moisture measurements. See also the Manual Part IX on Meteorological Measurements. The exact depth range of the soil core (top to bottom of core) is reported, along with the ring ID information. When forest floor thickness (OF + OH layer) is > 5 cm, the OF+OH layer should be sampled also with a suitable cylinder or frame. Optionally, extra mineral soil layers or horizons could be sampled that are considered relevant for the hydrological regime of the soil profile.
Table 6: Sampling scheme for core samples to determine soil water retention characteristic Matrix Depth interval (cm) Minimum number of Requirements for replicates Level II core plots per profile per plot Organic Layer OF+OH > 5 cm thick 1 3 Mandatory OF+OH <= 5 cm thick - - not required Mineral layer 0 - 20 cm 1* 3 Mandatory 20 - 40 cm 1* 3 Mandatory 40 - 80 cm 1* 3 Mandatory > 80 cm - - Optional Extra (specific) layer - - Optional (*) if the mineral layer is difficult to sample (e.g. caused by higher gravel content) a higher number of samples are strongly recommended. version 5/2010 17
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Concluding from Table 6, on each plot at least 9 undisturbed and representative samples should be taken if the forest floor is less than 5 cm thick and 12 samples if the forest floor is more than 5 cm thick. For each undisturbed sample, the pedogenetic horizon according to the designations given in Annex 7, should be reported that contains the centre of the sampling cylinder. The pedogenetic horizon may be deduced from the soil profile description of the sampled plot. Hence for each undisturbed core sample following information is reported: The exact depth range of the core cylinder in cm by reporting the depth of the upper and lower end of the cylinder (e.g. 10 -15 cm for a cylinder of 5 cm in height); Pedogenetic horizon containing the centre of the undisturbed sample (e.g. 12.5 cm is located in E horizon)
4.2 Sampling equipment
4.2.1 Pedological characterisation of the plot A list of field equipment for profile description is provided in Annex 4.
4.2.2 Soil sampling at fixed depths It is recommended to sample the organic layer with a frame of 25 by 25 cm, but alternatives with a minimum total surface of 500 cm2 are acceptable; for mor humus, an auger with a diameter of 8 cm can be used. Sampling of the organic layer can be done by hand, supported by trowel, knife, spatula and/or brush. For sampling of the mineral soil by auger, Annex 4 provides a list with recommended soil augers according to the soil texture type and moisture conditions. Further following equipment is essential: Field forms, pencils and permanent marker Folding meter Knife Spade Impact free hammer Spatula Electronic field balance and spare batteries (only when subsamples are taken) Recipients for transporting the samples plus labels Sampling tray for mixing the subsamples of the composite samples
4.2.3 Sampling of undisturbed soil core cylinders Undisturbed soil cores are taken in dedicated metal cylinders (sleeves) with a volume between 100 and 400 cm³. Plastic cylinders are dissuaded. The same steel cylinders can be used for the soil water measurements (method SA14) as for determination of bulk density (method SA04). The sample ring dimensions should be representative of the natural soil variability and structure. The most frequently met dimensions (height x diameter in mm) of cylinders for forest soil sampling are: 50 x 53 (100 cm³), 40.6 x 56 (100 cm³) and 50 x 79.8 (250 cm³). It is important to verify that the laboratory that will process the undisturbed samples is equipped for the type of sample rings
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used. The bottom of the sample ring should have a cutting edge. Plastic lids should perfectly fit to both ends of the steel cylinder. In a soil profile pit, undisturbed samples can be taken directly using the sample ring, without extra material. When sampling is done in a bore-hole, a closed ring holder is recommended. In conclusion, the sample material consists of: Steel cylinders (sample rings) with lids Open ring holder (optional) Closed ring holder (needed when sampling in boreholes) Spade and/or trowel for digging out the cylinder Impact absorbing hammer (for hard soil layers only) Small frame saw Spatula or knife Waterproof marker for labelling Plastic bags or foil for wrapping the rings
4.3 Sample collection
4.3.1 Pedological characterisation and profile pit sampling By profile sampling, using a knife and a tray the soil is gently loosened from the respective horizon. By using the tray any material that accidentally is included in the sampled material can easily be removed before the material is brought into the bag. As a general rule, and surely for taxonomic purposes, at least one sample per horizon should be taken. If a horizon is particular heterogeneous, e.g. due to strong mottling, it may be necessary to take several subsamples. Samples for chemical analyses can be collected in various ways. The mode of sampling should be recorded, as for example on a sample list and by means of either a simple sketch or by special photos. The chosen sampling procedure should reflect the soil variability within the horizon and naturally the purpose of the prospection. The “composite” sample: several soil samples are collected throughout the horizon. These samples can be kept separate. If, as for example, from profile 12 the 4 subsamples a, b, c and d are collected in horizon 2, this can be labelled P12H2a, P12H2b, P12H2c, P12H2d, or they can be mixed together in one bag and labelled e.g. P12H2. The “massed average” sample: is a sample taken throughout the whole (vertical) thickness of the horizon. The “middle” sample: is a sample taken more or less in the middle of the horizon, there where the characteristics of the horizon are best developed. For classification purposes, the “middle” sampling strategy is recommended.
4.3.2 Sampling at fixed depths
4.3.2.1 Organic layer sampling It is strongly recommended to make the description of the humus form simultaneously with the sampling of the organic layer. version 5/2010 19
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Either all subsamples coming from the inside of the frame or from the auger are taken individually to the lab to determine the dry mass (kg/m2), or the subsamples are first bulked in the field and subsequently a subsample is taken to the lab for further measurements. In the latter case, it is absolutely necessary that the fresh mass (kg/m2) of each subsample and each organic subhorizon is measured in the field using an electronic field balance. Record the total surface of each subhorizon (surface of the frame/auger * N° of subsamples) to allow stock calculations later on. The frame is pushed carefully in the forest floor. Then the organic subhorizons are separately cut out along the frame using a sharp knife. Be careful not to include any mineral soil material in the OH sample. Living material (such as mosses, roots, etc.) and objects > 2 cm in diameter are removed from the sample but smaller twigs, fruits remain to determine the mass of the sample.
4.3.2.2 Mineral soil sampling Augering is preferred but pits are allowed, especially in case of stony soils where augerings are difficult or impossible.
4.3.2.3 Size of samples The minimum mass of each representative sample for chemical analysis should be large enough for all laboratory analyses (mandatory and optional parameters) and possible repetitions or reanalyses in time. It is also advisable to keep the sample in a storeroom. The absolute minimum mass of samples (field mass) with no or little gravel should be 500 grams but 1 kg is recommended for important (reference) samples.
4.3.3 Cores for bulk density and soil water retention measurements The core method is applicable for stone-less and slightly stony soils. The samples are taken with core cylinders on horizontal sections. The sampling procedure for undisturbed soil sampling (core sampling in steel rings) is as follows: Take soil cores carefully to ensure minimal compaction and disturbance to the soil structure: In a soil pit, undisturbed samples can be taken by hand pressure directly using the sampling ring. Alternatively, an open ring holder may be used. In such a holder, the ring is locked by means of a rubber or lever. Over the ring some space headroom is left allowing for taking an oversize sample. This prevents the sample for compaction during sampling. In hard soil layers, an impact absorbing hammer may be used for hammering the ring holder into the soil. When sampling in a bore hole, a closed ring holder is recommended. This type of ring holder holds the cylinder in a cutting shoe. The ring is clamped inside the cutting shoe and no water or soil can come into the ring from the top. Moreover, the sample ring is protected, the sample is oversized on both sides and there is no risk of losing or damaging the sample ring. In hard layers, an impact absorbing hammer may be used with care. The ring sample is taken vertically with its cutting edge downwards; Dig out the cylinder carefully with a trowel, if necessary adjust the sample within the cylinder before trimming flush, trim rough the two faces of the cylinder with a small frame saw. A spatula or knife may be used but care has to be taken to avoid smearing the surface (closing macro- and mesopores). Close both sides of the cylinders with suitable lids.
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Record sampling date, sample grid reference, horizon encompassing the centre of the core, and the exact sampling depths (depth of top and bottom of the cylinder with respect to the top of the mineral horizon). Label the cylinder on the lid clearly with the sample plot reference, the sampling date, the horizon code and the sample depth; Wrap the ring samples in plastic bags or a plastic or aluminium foil to prevent from drying.
4.3.4 Excavation method for sampling for bulk density An alternative to core samples for bulk density, is sampling by the excavation method. Sampling of bulk density in stony soils is much more delicate, and surely much more time consuming than sampling in soils with none or little coarse fraction. First a carefully levelled horizontal section is prepared. A soil volume is then excavated. The volume required depends on the general coarse fraction content. For example if the coarse fraction makes up about 30% of the soil volume, a sample of 20 dm3 should be sufficient. While excavating the sample, compaction of the sides should be avoided. The sample is stored in a plastic bag, avoiding any compaction. Line the excavation hole with a thin but strong plastic film, fill the hole to excess with a known volume of sand. The hole is filled using a funnel kept 5 cm above the ground, level the surface and avoid compaction. Remove the excess sand into a graduated measuring cylinder, and read the volume. Calculate the total volume of sand filled into the excavation hole (see also Annex 1, SA04).
4.4 Sample storage and transport The sample recipient should be properly labelled with a comprehensive code preferentially including location name, plot number, profile number, horizon number or layer name, depth of sample, and sampling date. In the field all the samples either in bags, boxes, metal rings etc. should never be left exposed to the open air and sun. Otherwise water will evaporate from the sample and condense in the same bag or recipient, and there is a risk of ultra-desiccation. The warming up of the sample will also activate the biologic activity within the sample. Samples for standard soil laboratory analyses are mostly kept either in plastic bags or boxes. If using plastic bags, the bags with a closing zipper and with a special label for writing the sample code are recommended. Also feasible is sampling and transporting the samples in plastic bags and then transferring them into plastic boxes for drying and laboratory treatments. The undisturbed samples are transported in plastic boxes or aluminium cases. They protect the samples from heat, humidity or dust. If transported in vehicles over long distances, shocking of samples should be avoided by using shockproof materials. Prevent undisturbed soil samples from freezing. Store the samples at 1 to 2 °C to reduce water loss and to suppress biological activity until analysis. It is recommended to avoid weeks of storage of undisturbed soil samples. Ideally, undisturbed soil samples are analysed in the lab immediately after sampling. The indoor preparation of the soil samples for further laboratory work is based on the ISO 11464 (1994) method (Soil quality – pretreatment of samples for physico-chemical analysis). Collected samples should be transported to the laboratory as soon as possible and air dried or dried at a temperature of 40 °C (ISO 11464, 1994). They can then be stored until analysis. To recalculate the analysis results on mass basis, the moisture content of the sample has to be determined by oven- drying the sample once at 105°C (ISO 11465, 1993). Living macroscopic roots and all particles, mineral and organic, with a diameter larger than 2 mm, should be removed from the samples by dry sieving as a preparation for analysis. The particles not version 5/2010 21
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passing the 2-mm sieve are weighed separately for the determination of the coarse fragments content (required for bulk density). To guarantee a harmonised approach, samples should not be further milled or ground. For those analyses for which finely ground material is required [e.g. Carbonate content (SA07), Total Organic Carbon (SA08), Total Nitrogen (SA09) and Total Elements (SA12)] further milling or grounding is allowed.
4.5 Long-term storage of soil samples The sample material for long-term storage should be kept without preservative under normal room conditions with minimal temperature and humidity fluctuations, shielded from incident light. When the humidity in the storage room cannot be controlled, the soil samples should be kept in air-tight containers. The samples should be stored at least till the next soil inventory.
5. Measurements
5.1 Physical characterization
5.1.1 Amount of organic layer This is the determination of the mass of the organic layer (volume-dry mass, kg/m2). For the method of soil moisture content, see Annex 1, SA02. In the field, the total fresh mass of each layer (OL, OF and OH or Hf, Hsf, and Hs) has to be determined, preferably together with the thickness of the concerning layer. Of each layer a subsample is collected for determination of moisture content (mass %) in the lab in order to calculate its total dry mass (kg/m2).
5.1.2 Particle size distribution The determination of the soil granulometry and classification according to the USDA-FAO textural classes (Figure 1) is mandatory for the mineral layers for Level II, only if not already determined during the first survey (no repetition required if this parameter was already measured). The particle size classes of the fine earth fraction (< 2 mm) are defined as follows (FAO, 2006): Clay < 2 m Silt 2 – 63 m Sand 63 – 2000 m For Level I, information on textural class for the mineral layers is mandatory too (though again only if not done in the first survey). However, for Level I an estimate based on the finger test in the field on 1 composite of each layer can be accepted for classifying the soil texture according to the USDA-FAO textural classes. In addition an estimate of the clay content is mandatory as well. Practical guidelines can be consulted in Annex 6. Repetition of the determination of the granulometry is not required. For Level I, extra time and costs are minimised if estimated by finger test (described in Annex 6). Method Level I: finger test for estimation of soil texture classified according to USDA-FAO texture triangle (FAO, 1990), and for estimation of the clay content (%). Optional: reference method as described for Level II. Level II: reference method as described in Annex 1: SA03
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Figure 1: Relation of constituents of the fine earth by size defining textural classes and sand subclasses. Textural classes based on USDA (1951), adopted by FAO (1990) and refined by FAO (FAO, 2006) version 5/2010 23
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5.1.3 Bulk density of the total mineral soil Definition Bulk density is defined as the mass of a unit volume of oven dry soil. The volume includes both solids and pores. In mineral soils without coarse fragments the bulk density of the total mineral soil is equal to the bulk density of the fine earth. Optional and mandatory parameters Three values of bulk density have to be reported mandatory for the mineral topsoil (0-10 cm, 10- 20 cm and 20 – 40 cm) of non-stony soils. For Level I, these values may be obtained either by estimation, pedotransfer functions or measurement. For Level II, the bulk density has to be measured. Determination of the bulk density of the 40-80 cm layer is optional for both Levels. No re-measurement is required if this parameter was determined according to the reference method for the first survey. Methodology For measurement: five samples have to be taken with a minimal volume of 100 cm3 per plot and per layer. In addition, the determination of bulk density requires estimation of coarse fragments according to the USDA-FAO classes (FAO, 1990). The latter can be measured or estimated in the soil profile. This estimation according to the fixed depths shall be done in addition to the normal profile description which follows the genetic layers.
5.1.4 Coarse fragments Coarse fragments group all gravel, stones and boulders with a diameter larger than 2 mm. The size classes according to the greatest dimension of the individual gravels/stones are defined in Table 7.
Table 7: Size classes of the coarse fragments (FAO, 2006) SIZE (CM) CLASS NAME 0.2 – 0.6 Fine gravel 0.6 – 2.0 Medium gravel 2.0 – 6.0 Coarse gravel 6 - 20 Stones 20 - 60 Boulders 60 - 200 Large boulders Report the amount of coarse fragments of the individual mineral layers in volume %. The abundance of coarse fragments can be measured in the laboratory, but is usually estimated during routine soil profile observations. In the case that very coarse materials are present (stones and boulders), the quantity of these materials has to be estimated in the field. Two methods are recommended: (i) the method established in Finland as described in Annex 1, SA05 or (ii) the method used in Germany (see Annex 1, SA04). The determination of coarse fragments is mandatory for the 0-10, 10-20 and 20-40 cm mineral layer and optional for 40 - 80 cm mineral layers in both Level I and Level II. In case of re- assessment (if this parameter was already measured according to the reference method in first survey) the parameter is optional. For Level I the parameter may be estimated, for Level II it must be measured using the methods described in Annex 1: SA05.
5.1.5 Combined approach to estimate bulk density of the fine earth and the content of coarse fragments Recent investigations (Riek and Wolff, 2006) have revealed that the soil physical parameters (in this case bulk density and fine earth stock) can only be recorded with field methods at specific locations in an inadequate or scarcely reproducible manner. This applies to soils with a high content of coarse gravel and/or the presence of stones and boulders. Because of their low 24 www.icp-forests.org/Manual.htm
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volume, the core samplers normally used in forest monitoring are unable to representatively collect stones or large portions of coarse fragments in the field. In these cases, the excavation method may produce good results but it may be too expensive, time-consuming and destructive in the framework of large-scale monitoring. The combined approach can improve the determination of these parameters at locations with a high content of coarse gravel and/or the presence of stones and boulders and lead to a better approximation of the real coarse fragments content. In the case of a high content of coarse gravel and/or the presence of stones and boulders, the quantity of bulk density of both fine earth and coarse fragments has to be estimated / sampled in the field. Methods should be selected according to the prevailing conditions (i.e. coarse fragment content and size) at each individual sampling site. In the analysis each method or each combined method leads to the determination of (partially) different parameters which means that different calculation formulas are needed. A description of the different methods and/or combined methods, the related parameters and calculation methods are described in Annex SA04. If the mineral soil contains no coarse fragments or the (estimated) coarse fragment portion is less than 5 % (case 1), then the bulk density of the fine earth (BDfe) is approximately equivalent to the bulk density of the total mineral soil (BDs) (see paragraph 5.1.3). In case of mineral soils with a coarse fragment content of more than 5% which can be sampled with a core sampler or any other (representative) sampler for coarse fragments < 20 mm (case 2), a representative volume sampling with core sampler, root auger, AMS core sampler with liner or hollow stem auger is done. When calculating the bulk density of the fine earth, the volume of the coarse fragment content is subtracted from the total volume of the sampler and the mass of the coarse fragments subtracted from the mass of the fine earth referring to this volume. In case the mineral soil cannot be representatively sampled with a core sampler or any other samples (coarse fragments > 20 mm) (case 3), there are two possibilities of taking the coarse fragments into account. The amount of coarse fragments has to be estimated in the field or be determined by additional sampling with a shovel or a spade (representative volume sampling). When representative volume sampling is not possible, sampling with mini-core samplers and estimation at the profile (coarse fragments > 60 mm) is required (case 4). The bulk density of the fine earth in the spaces between the coarse material [soil skeleton] is determined with a mini-core sampler. In addition, a disturbed spade /shovel sample is taken in order to determine factor f (correction factor for a possible coarse fragment portion in the mini-core sampler). Furthermore, the coarse fraction portion > 60 mm is estimated at the profile.
5.1.6 Determination of the soil water retention characteristic (SWRC) In order to determine the SWRC, the volumetric water content (θ in volume fraction, m3 m-3) is determined at predefined matric potentials (ψ, in kPa). As indicated in Table 8, six of these matric heads are mandatory to determine. Extra observations of the SWRC at pressures -10, -100 and - 250 kPa are optional but they greatly improve fitting the SWRC. Some matric heads immediately provide information on SWRC parameters: at 0 kPa the maximum water holding capacity (WHC) of the saturated soil sample is determined; depending on definitions and soil texture field capacity (FC) may be inferred from -10 till -100 kPa; permanent wilting point (PWP) is attained at a matric pressure of – 1500 kPa and dry bulk density (lowest pressure at about 10-6 kPa) derived in the oven at 105°C. The standard instruments required for each determination are listed in Table 8. The reference methods for all physical parameters are listed in Table 9.
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Table 8. Overview of matric heads to assess for the determination of the SWRC Matric potential ψ Recommended Estimator Equivalent M/O instrument pore size diameter cm pF kPa Jurin’s law, H2O Hillel (1980) 1 infinitely 0 Pycnometer ≈θsat= water > 1 mm M small holding capacity = Total porosity 10 1.0 -1 300 μm M 51 1.7 -5 Sand suction table 60 μm M 102 2.0 -10 Field capacity sand 30 μm O 337 2.5 -33 Field capacity 10 μm M Kaolin suction table siltloam 1022 3.0 -100 Field capacity clay 3 μm O Pressure plate 2555 3.4 -250 1.2 μm O extractor or pressure 15330 4.2 -1500 Permanent wilting 0.2 μm M membrane cells point 107 7.0 -106 Oven Dry BD 0.0003 μm M Where: 1) the pF is the logarithm of the absolute value of the matric potential expressed by the graduation of the water column (cm). 2) 1 kPa = 10.22 cm H2O or 1 cm H2O column = 0.097885 kPa 3) 100 kPa = 1 bar
Table 9: Overview of the reference methods for physical parameters Parameter Reference Method Unit Particle size distribution Pipette method % (sand, silt, clay fractions) Finger test method (only allowed on Level I) Coarse fragments Laboratory measurement vol% Field estimate during soil profile description Soil water retention 0 kPa: Pycnometer measurement m3/m3 characteristic -1 till – 10 kPa: Sand suction table - 33 kPa: Kaolin suction table -100 till -1500 kPa Pressure plate extractor or pressure membrane cells Bulk density Oven drying at 105°C kg/m3 Volume dry mass of organic 1) Field measurement of total fresh mass kg/m2 layer 2) Field measurement of the horizon thickness cm 3) Determination of moisture content in the laboratory mass%
5.2 Chemical characterization of collected samples
5.2.1 Selected key soil parameters for the Level I and II Survey An overview of the key parameters to be measured is presented in Table 10. Note that the minimum requirement for a number of the mandatory parameters, indicate that in the mineral 26 www.icp-forests.org/Manual.htm
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layers below 20 cm the parameters should be measured once and not necessarily be re-measured a second time. Temporal changes are in the first place expected in the upper layers. Mandatory Level II parameters of the deeper layers (20-40 and 40-80 cm) that were already measured with the reference methods for the first survey, do not have to be determined again except for organic carbon that should be remeasured in the 20 to 40 cm layer. This means that if all the mandatory parameters of the 40-80 cm layer were assessed with the reference method, re-sampling of this layer is not required. With regard to the nutrients, the amount extracted by aqua regia is mandatory for the OF+OH horizons and H layers of the organic layer and optional for the mineral topsoil. While from this extraction not the real total content is obtained, it is useful as an estimate of the nutrient stock. Extra costs and work are minimal as it can be measured from the same extraction to be made for the heavy metals (mandatory for both the OF+OH horizons, H-layers and the mineral topsoil). For the determination of the 'real' total amounts, more specialised material and skill are required. As these 'real' total contents are important for the calculation of weathering rates and critical loads, they are optional for the mineral layers of Level II. Note that the measurement of carbonates is required also for the correction of the organic carbon content if the pH(CaCl2) > 5.5 in the organic and > 6 in the mineral layer.
For the determination of the pH, measurement on a CaCl2-extract is mandatory. pH(H2O) has been made an optional parameter for reasons of comparability, as this is mostly used in literature.
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Table 10: Chemical and physical key soil parameters on the samples taken at fixed depths(1) Parameter Unit Level I Level II Organic Layer Mineral Layer Organic Layer Mineral Layer
mals OL OF+OH, 0-10 cm 10-20 cm 20-40 40-80 cm OL OF+OH, H 0-10 cm 10-20 cm 20-40 40-80 Deci- H- (2) cm (2) cm cm Physical soil parameter Organic layer mass kg/m2 2 O M - - - - O M - - - Coarse fragments vol % 0 - - M (3), (4) M (3) (4) M (3) (4) O (4) - - M M (3), (4) M (3), (4) O (4) Bulk density of the fine earth kg/m3 0 - - M (3), (5), (6) M (3), (5), (6) M (3), (5), O - - M (3), (5) M (3), (5) M (3), (5) O (6) Particle size distribution (FAO, - - - - M (3), (7) M (3), (7) O O - - M (3) M (3) M (3) M (3) 1990) Clay content % 1 - - M (3), (7) M (3), (7) O O - - M (3) M (3) M (3) M (3) Silt Content % 1 - - O O O O - - M (3) M (3) M (3) M (3) Sand Content % 1 - - O O O O - - M (3) M (3) M (3) M (3) Chemical soil parameter (3) (3) pH(CaCl2) - 2 - M M M O O - M M M M M pH(H2O) - 2 - O O O O O - O O O O O Total organic carbon g/kg 1 - M M M M O - M M M M O Total nitrogen g/kg 1 - M M M O O - M M M O O Carbonates g/kg 0 - M (8) M (8) M (8) O O - M (8) M (8) M (8) O O Aqua Regia extracted mg/kg 1 O M O O O O O M O O O O P, Ca, K, Mg, Mn Aqua Regia extracted mg/kg 1 O M M - - - O M M - - - Cu, Pb, Cd, Zn Aqua Regia extracted mg/kg 1 O O O - - - O O O - - - Al, Fe, Cr, Ni, S, Hg, Na + (9) (9) (9) (9) 9) (9) (3), (9) (3), (9) Exchangeable Acidity, Free H , cmol(+)/kg 2 - M M M O O - M M M M M Exchangeable cations Al, Fe, Mn (9) (9) (3) (3) Exchangeable cations Ca, Mg, K, cmol(+)/kg 2 - M M M O O - M M M M M Na Total Elements: mg/kg 1 ------O O O O Ca, Mg, Na, K, Al, Fe, Mn Oxalate extractable Fe, Al mg/kg 1 - O O O O O - O M M M (3) M (3) 1 Abbreviations : M = mandatory parameter, O = optional parameter 2 If the OH - horizon > 1 cm, the OF - and the OH - horizons should be analysed separately and each value has to be reported 3 In case of a re-assessment (if the parameter was already measured according to the reference method for the first survey) , the measurement is optional 4 May be obtained by estimation or measurement 5 Mandatory only in non-stony soils 6 May be obtained by estimation, pedo-transfer function or measurement 7 May be obtained by finger test, consists of texture classified according to USDA-FAO texture triangle 8 Only mandatory if pH(CaCl2) > 5.5 or in calcareous soils 9 In calcareous soil, the measurement of this parameter is optional
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This means that if all the mandatory parameters of the 40-80 cm layer were assessed with the reference method, re-sampling of this layer is not required. With regard to the nutrients, the amount extracted by aqua regia is mandatory for the OF+OH horizons and H layers of the organic layer and optional for the mineral topsoil. While from this extraction not the real total content is obtained, it is useful as an estimate of the nutrient stock. Extra costs and work are minimal as it can be measured from the same extraction to be made for the heavy metals (mandatory for both the OF+OH horizons, H-layers and the mineral topsoil). For the determination of the 'real' total amounts, more specialised material and skill are required. As these 'real' total contents are important for the calculation of weathering rates and critical loads, they are optional for the mineral layers of Level II. Note that the measurement of carbonates is required also for the correction of the organic carbon content if the pH(CaCl2) > 5.5 in the organic and > 6 in the mineral layer.
For the determination of the pH, measurement on a CaCl2-extract is recommended. pH(H2O) has been made an optional parameter for reasons of comparability, as this is mostly used in literature.
5.2.2 Reference analytical methods The full description of the reference methods is given in Annex 1. Table 11 gives an overview of the reference methods for the chemical parameters. Note that the parameters are grouped according to the analytical method. As such it is obvious which elements can be measured in the same run, without additional costs and hardly extra work involved.
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Table 11: Overview of reference methods for the chemical parameters Parameter Reference Analysis Method 1 Unit 2 Measurement ISO Extractant method(s) 3 pH(CaCl2) ISO 10390 (2005) 0.01 M CaCl2 pH-electrode pH(H2O) H2O pH-electrode ISO 13878 (1998) - Dry Combustion g/kg Total nitrogen ISO 11261 (1995) - Modified Kjeldahl
4 ISO 10694 (1995) - Dry Combustion at 900 Total organic carbon °C Carbonates ISO 10693 (1994) HCl Calcimeter P Colorimetry mg/kg
K, Ca, Mg, Mn IC AAS Aqua Regia P
Heavy metals: Cu, Cd, ISO 11466 (1995) by reflux Pb, Zn digestion Other: Al, Fe, Cr, Ni, Na Hg IC Cold vapour AAS P ICP S CNS - analyser Free Acidity (or sum of ISO 11254 (1994) 0.1 M titration to pH 7.8 5 + cmol(+)/kg AC ) and free H modified BaCl2 or 'German' method Al, Fe, ISO 11260 (1994) - Exchangeabl Mn modified 0.1 M ICP AAS e Cations K, Ca, BaCl2 FES Mg, Na Reactive Fe and Al ISRIC (2002) Acid AAS ICP mg/kg ammonium oxalate Total Elements: Ca, ISO 14869-1 (2001) HF or AAS ICP mg/kg Mg, Na, K, Al, Fe, Mn LiBO2 1 Reference and full descriptions are given in Annex 1 2 Results have to be expressed on an oven dry basis 3 For the measurement of a number of parameters there are several alternatives for the equipment that can be used 4 Note that for total organic carbon a correction has to be made for total inorganic carbon (carbonates) 5 Alternative for the titration of the exchangeable acidity is the sum of the exchangeable Al, Fe, Mn and free H+
5.3 Data quality requirements The quality of the soil analytical data is controlled by the regular organisation of Interlaboratory Comparisons (ring tests) by the Forest Soil Co-ordinating Centre. Each soil laboratory participating in the ICP Forests programme should be qualified for the reported parameters. For qualification procedures, see Manual Part XVI on Quality Assurance and Control in Laboratories. Information on the performance of the concerning soil laboratory is reported to the data centre at each submission period.
5.3.1 Plausibility limits See Manual Part XVI on Quality Assurance and Control in Laboratories, Table 3.3.2.1a “Plausible ranges for organic and mineral soil samples at the European level.” Laboratories are invited to check the data that are outside these plausibility limits before reporting.
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Plausibility limits for SWRC of mineral forest soils and organic layers will be developed in the future.
5.3.2 Data completeness Tables 9 and 11 outline for all the physical and chemical soil parameters whether and under which conditions they are mandatory or optional to report. When a country/federal state decides to report optional parameters, they should also fulfil the data quality requirements. Soil water retention data are considered complete if volumetric water content for all six mandatory matric heads (see Table 9) is determined. For scientific reasons analysing the optional matric heads also is strongly recommended. Interpolation of volumetric water content between matric pressures is not allowed.
5.3.3 Data quality objectives or tolerable limits See Manual Part XVI on Quality Assurance and Control in Laboratories, Tables 3.4.1.2.2 for the tolerable limits of the measured parameters in the FSCC Interlaboratory Comparisons. Tolerable limits for the determination of the SWRC for laboratory performance will be derived from the reproducibility data gained by performing interlaboratory physical soil ringtests. All reported values should have been measured according to the methods described in Annex 1.
5.3.4 Data quality limits The laboratory results are considered of sufficient quality when the laboratory received a qualification for the concerning parameter(s) after participation in the FSCC Interlaboratory Comparisons. The soil chemical Interlaboratory Comparisons should include at least 5 soil samples (mineral and organic). When 50% of the samples in the ring test are within the tolerable limits, the laboratory is qualified to analyse the concerning parameter and the survey results can be reported to the central database.
6. Data handling
6.1 Data submission procedures and forms Forms for data submission and explanatory items are found on the ICP Forests web page, at http://www.icp-forests.org/Manual.htm. The quality information on the labs has to be sent together with the PLS, PRF, PFH, SOM, SWC and SWA forms to the data centre using the submission form "XX2011SO.LQA" or updated version valid for year of submission. The following rules apply: Data will be reported for the H- and O-horizons and for the mineral soil. For the organic layers reporting is done according to the OL-, OF-, OH-, OFH-, Hf, Hs, Hfs horizons or as described in Annex 7 of this Part of the Manual. For the mineral soil, reporting is done according to the defined mandatory depth layers. For the peat layers, reporting is done according to the defined depth layers (Mandatory: H01, H12 and Optional: H24 or H48) and following the parameter list for the OF, OH and H-layers of the organic horizons. version 5/2010 31
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6.2 Data validation Data checks should be done as soon as results from the analyses are available. Data validation and quality assurance should be applied in accordance with the guidelines for QA/QC procedures in the laboratory that are given in Manual Part III on QA/QC in laboratories (§ 3.3.2.2: Cross checks between soil variables).
6.3 Transmission to co-ordinating centres, with timetable and rules All validated data should be sent to each national focal centre and to the European central data storage facility at the ICP Forests Programme Coordinating Centre. Detailed time scheduled is provided by the relevant bodies.
6.4 Data processing guidelines
6.4.1 Derived soil parameters Chemical derived soil parameters such as cation exchange capacity (CEC), Base Saturation (BS), C:N ratio, C:P ratio are not reported, but are directly calculated from organic carbon, total nitrogen and phosphorus, exchangeable cations, acidity and Free H+. A typical example of derived soil physical parameters is the available water capacity (AWC), field capacity (FC), wilting point (WP) and total porosity which may be derived from the SWRC. Soil water retention curve models are fitted to the raw data. For forest soils, one of the best performing functions is the Van Genuchten equation defined by its empirical parameters θr, θs and empirical constants α, n and m = 1-1/n. Calculation of these parameters can be done using the public domain RETC programme which may be downloaded from: http://www.pc- progress.cz/Pg_RetC.htm or obtained from the FSCC. This software enables to predict Ksat from the SWRC measurements. The Van Genuchten model parameters should also be stored.
6.4.2 Data Classification When presenting the forest soil condition data of Level I on a map, a selection of classes is required. The number of classes is best limited. The limits are then selected in function of the frequency distribution of the parameter results. In case the results approximate a normal distribution, class limits are chosen more or less symmetrically around a central class. The difference between upper and lower class limits are kept constant, consequently more results are assigned to the middle class. However, most parameters results are not normally distributed. Often the distributions are positively skewed, showing a tail towards larger values. In order to obtain a distribution of results among the classes similar to normally distributed parameters, the differences between upper and lower class limits are gradually increased. For the classification of elevated heavy metal concentrations, use is made of available ‘toxic’ values found in literature and critical levels.
6.4.3 Clustering Soil Observation Plots Soil chemical properties usually vary within a wide range. They are influenced by many external factors such as climate, soil parent material, age of the soil material and vegetation type. Evaluation of the soil condition based at a large number of observation sites involves the study of relationships among individual soil properties and among soil properties and external influencing factors. In order to investigate these relationships statistically, the need arises to compare groups of individual soils, having similar properties. Considering the site factors that determine forest soil
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conditions and limitations associated with data availability, the following criteria for clustering each soil observation plot can be used: climatic region, atmospheric deposition load, soil type, parent material class, texture class, humus type, biogeographical region,…
6.4.4 Statistical methods For each parameter, three statistical approaches can be applied: 1. Descriptive statistics (boxplots, histograms, frequency distributions, means, percentiles, etc) 2. Classical statistical data analysis and testing (parametric and non- parametric methods) 3. Geostatistical approach (including the spatial component) The statically obtained information offers opportunities for further modelling.
6.5 Data reporting Data should be accompanied by a “Data accompanying report” (DAR) and any other information requested by the European central data storage facility. The DAR should include all details on sampling and analytical procedures. In addition, irregularities in sampling and analytical procedure, missing data, estimated values and encountered errors in the validation, should be documented. All details on how data are treated and how the calculations are made shall be documented and shall accompany the result to the data storage facility. If values are below the quantification limit (not the detection limit), a value of -1 should be reported. Definitions of the quantification and detection limits can be found in Section 3.2.3 of the Manual Part III on Quality Assurance and Quality Control in Laboratories.
7. References
Adams W.A. 1973. The effect of organic matter and true densities of some uncultivated podzolic soils. Journal of Soil Science, 24, 10-17. De Vos, B., Van Meirvenne, M., Quataert, P., Deckers, J. and Muys, B. 2005. Predictive quality of pedotransfer functions for estimating bulk density of forest soils. Soil Sci. Soc. Am. J. 69: 500-510. FAO. 1990. Guidelines for soil description (3rd edition). Soil Resources, Management and Conservation Service. Land and Water Development Division, Food and Agricultural Organization of the United Nations, Rome. FAO. 2006. Guidelines for Soil Profile Description and Classification (4th edition) by R. Jahn, H.-P. Blume, V.B. Asio, O. Spaargaren and P. Schad (Eds) and by R. Langohr, R. Brinkman, F.O. Nachtergaele and P. Krasilnikov (Contributors), FAO, Rome. Hillel, D. 1980. Fundamentals of soil physics. Academic Press Inc., London. ISO 11464. 1994. Soil Quality – Pretreatment of samples for physico-chemical analysis. International Organization for Standardization. Geneva, Switzerland. 9 p. ISO 11465. 1993. Soil Quality –Determination of dry matter and water content on a mass basis – Gravimetric method. International Organization for Standardization. Geneva, Switzerland. 9 p. ISO 8258. Shewart control charts. International Organization for Standardization. Geneva, Switzerland. 29 p. version 5/2010 33
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IUSS Working Group WRB. 2006. World Reference Base for Soil Resources 2006. World Soil Resources Reports No. 103. FAO, Rome IUSS Working Group WRB. 2007a. World reference base for soil resources 2006, first update 2007. World Soil Resources Report No. 103. FAO, Rome. IUSS Working Group WRB 2007b. World Reference Base for Soil Resources 2006. Erstes Update 2007. Deutsche Ausgabe. – Übersetzt von Peter Schad. Herausgegeben von der Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover. Rawls W.J., Brakensiek, D.L. 1985. Prediction of soil water properties for hydrologic modeling, in Proceedings of Symposium on Watershed Management, ASCE, pp. 293-299. U.S. Dept. of Agriculture. Soil Conservation Service. Soil Survey Staff. 1951. Soil Survey Manual. U.S. Dept. of Agric. Handb. 18. U.S. Govt. Print. Off. Washington, DC. 503 pp., illus. Zanella A., Jabiol B., Ponge J.F., Sartori G., de Waal R., Van Delft B., Graefe U., Cools N., Katzensteiner K., Hager H., Englisch M., Brethes A. 2009. Toward a European humus forms reference base. Studi Trent. Sci. Nat., 85: 145-151. © Museo Tridentino di Scienze Naturali, Trento, 2009. ISSN 2035-7699.
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Annex 1 Methods for Soil Analysis
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Soil Analysis Method 1 (SA01) Pre-treatment of Samples
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Pre-treatment of Samples Method sheet SA01 Reference methods ISO 11464 Method suitable for Organic Layer; Mineral Layer
I. Relevance in ICP Forests
All samples (organic and mineral) have to be prepared according to the standard methodology in order to maintain comparability among participating countries.
Priority Level I Level II Organic Layer OL Optional Optional OF+OH, H-layers Mandatory Mandatory Mineral layer 0- 10 cm 1 Mandatory Mandatory 10 – 20 cm Mandatory Mandatory 20 – 40 cm Mandatory Mandatory 40 – 80 cm Optional Mandatory 1 Optionally this layer may be split in two layers: 0 – 5 cm AND 5 – 10 cm
II. Principle a. Organic layer After removal of living material (such as mosses, roots, etc.) and objects > 2 cm, collected samples (preferably not less than 500 g fresh material) should be transported to the laboratory as soon as possible and should be air dried or dried at a temperature of 40 °C. They can then be stored until analysis. The sample is subsequently crushed or milled to size < 2 mm. When the samples are bulked in the field and only a subsample is taken to the laboratory, the fresh mass (kg/m2) of each organic sublayer should be measured in the field. Further it is strongly recommended to measure the thickness of each organic sublayer in each subsample in the field. Firstly, because the horizon thickness (in cm in terms of the upper and lower limit) is mandatory to report in the profile description file. Secondly it is useful as a cross check. b. Mineral layer After removal of living material (such as mosses, roots, etc.) and objects > 2 cm, collected samples (preferably not less than 500 g fresh soil) should be transported to the laboratory as soon as possible and should be air dried or dried at a temperature of 40 °C. They can then be stored until analysis.
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Living macroscopic roots and all material, mineral and organic, with a diameter larger than 2 mm, should be removed from the samples by dry or wet sieving. The particles not passing the 2-mm sieve (after crushing), may be weighed separately for the determination of the coarse fragments content (SA05). The fraction smaller than 2 mm is used for the soil analysis. The mineral soil samples should not be milled. Only sieving above a 2 mm sieve is allowed. No further grinding will be allowed except for the analysis of Carbonate content (SA07), Total Organic Carbon (SA08), total Nitrogen (SA09) and Total Elements (SA12). The sample materials for storage should be kept without preservative under normal room conditions with minimal temperature and humidity fluctuations, shielded from incident light.
III. Apparatus
Drying oven. Crusher, mill, mortar and pestle. Plate sieve, mesh sieve
IV. Reagents
No reagents.
V. Procedure
Drying Spread the material in a layer not thicker than 15 mm. If necessary, the sample is crushed while still damp and friable and again after drying. Dry the complete sample in a drying oven at a temperature of 40 ° C, until the loss in mass of the sample is not greater than 5 % (m/m) per 24 h. Break down the size of larger clods (greater than 15 mm) to accelerate the drying process. Removal of fraction < 2 mm Remove stones and large objects by hand picking and sieving (< 2 mm). Minimise the amount of fine material adhered. Weigh separately the fraction not passing the 2 mm sieve for determination of coarse fragment content. Crush (not ground) the clods greater than 2 mm taking care that crushing of original particles is minimised. Homogenise the < 2 mm fraction. Sieving and Milling The organic sample is crushed or milled to size < 2 mm. The mineral soil samples should not be milled. Only sieving above a 2 mm sieve is allowed. No further grinding will be allowed except for the analysis of Total Organic Carbon (SA08), Total Nitrogen (SA09) and Total Elements (SA12). Subsampling For the preparation of an analysis subsample, split up (by hand, using a sample divider or by mechanical subsampling) the sample into representative portions until the required sample number and sample size is obtained.
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VI. Calculation
No calculations.
VII. Report
The mineral fractions (> 2 mm) obtained after sieving with a 2 mm sieve may be used for determination of coarse fragments (SA05).
VIII. Reference
ISO 11464. 1994. Soil Quality – Pretreatment of samples for physico-chemical analysis. International Organization for Standardization. Geneva, Switzerland. 9 p. (available at www.iso.ch)
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Soil Analysis Method 2 (SA02): Determination of Soil Moisture Content
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Soil Moisture Content Method sheet SA02 Reference methods ISO 11465 Method suitable for Organic Layer; Mineral Layer
I. Relevance in ICP Forests
Recalculation of results obtained by lab analysis to “oven-dry mass”.
Priority Level I Level II Organic Layer OL Optional Optional OF+OH, H-layers Mandatory Mandatory Mineral layer 0- 10 cm 1 Mandatory Mandatory 10 – 20 cm Mandatory Mandatory 20 – 40 cm Mandatory Mandatory 40 – 80 cm Optional Mandatory 1 Optionally this layer may be split in two layers: 0 – 5 cm AND 5 – 10 cm
II. Principle
Calculation and reporting of the results of soil analysis is done on basis of "oven-dry" soil. The moisture content of air-dry soil is determined prior to soil analysis. To recalculate the analysis results on dry mass basis, the moisture content of the sample has to be determined by oven- drying a sample to constant mass. The difference in mass is used to calculate water content on a mass basis.
III. Apparatus
Moisture tins or flasks (25 – 100 ml) with closely fitting lid Drying oven Analytical balance (accuracy 0.001 g) Note: The use of an automated apparatus for measuring soil moisture content is allowed as long as it is based on the same principle.
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IV. Reagents
No reagents.
V. Procedure
Mineral Layer: Transfer 5-15 g air-dried fine earth (fraction < 2 mm) to a dried, tared moisture tin and weigh. Dry at 105±5 °C (lid removed) until constant mass is reached. Organic Layer : Transfer 5 – 10 g air dried organic layer material to a dried, tared moisture tin and weigh. Dry at 105 °C (lid removed) for 24 hours. Remove tin from oven, close with lid, cool in desiccator and weigh.
VI. Calculation
The moisture content in mass percentage is obtained by : − BA Moist% = * 100 B − tare tin Where: A : Mass of tared moisture tin and air-dried soil sample B : Mass of tared moisture tin and oven-dried soil sample The corresponding moisturecorrection factor for analytical results or for amount of sample to be weighed in for analysis is: 100 + moist% moisture correction factor(MCF) = 100 Note: when reporting the results of Carbonate Content (SA07), Total Organic Carbon (SA08), Total Nitrogen (SA09), Exchangeable acidity, Free H+, Exchangeable elements (SA10), Aqua Regia Extractable elements (SA11), Total elements (SA12), Acid Oxalate Extractable Fe and Al (SA13), the results on air- dry basis should be multiplied by the moisture correction factor (MCF) to obtain the result on oven-dry basis.
VII. Report
Report moisture content (in %) with 1 decimal place.
VIII. Reference
ISO 11465. 1993. Soil Quality – Determination of dry matter and water content on a mass basis – Gravimetric method. International Organization for Standardization. Geneva, Switzerland. 3 p. (available at www.iso.ch)
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Soil Analysis Method 3 (SA03): Determination of Particle Size Distribution
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Particle Size Distribution Method sheet SA03 Reference methods ISO 11277 Method suitable for Mineral Layer
I. Relevance in ICP Forests
Particle Size Distribution : USDA-FAO texture Classification and Clay Percentage
Priority Level I Level II Organic Layer - - Mineral layer 0 – 10 cm Mandatory1, 2 Mandatory1 10 – 20 cm Mandatory1, 2 Mandatory1 20 – 40 cm Optional Mandatory1 40 – 80 cm Optional Mandatory1 1 if not determined in the first soil survey 2 an estimation of clay content based on finger test is allowed
Particle Size Distribution : Silt and Sand Percentage
Priority Level I Level II Organic Layer - - Mineral layer 0 – 10 cm Optional Mandatory1 10 – 20 cm Optional Mandatory1 20 – 40 cm Optional Mandatory1 40 – 80 cm Optional Mandatory1
1 if not determined in the first soil survey
II. Principle
Separation of the mineral part of the soil into various size fractions and determination of the proportion of these fractions. The analysis includes all soil material, i.e. including gravel and coarser material, but the procedure below is applied to the fine earth fraction (< 2 mm) only. Of
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paramount importance in this analysis is the pretreatment of the sample aimed at complete dispersion of the primary particles. Therefore, generally, cementing materials (usually of secondary origin) such as organic matter, salts, iron oxides and carbonates such as calcium carbonate are removed. After shaking with a dispersing agent, sand (63 μm-2 mm) is separated from clay and silt with a 63 μm sieve (wet sieving). The clay (< 2 μm) and silt (2-63 μm) fractions are determined by the pipette method (sedimentation).
III. Apparatus
Sampling pipette (10 to 50 ml) with safety bulb and water reservoir, held in frame Constant temperature room or thermoregulated bath (20 – 30 °C 0.5 °C) Glass sedimentation cylinders (approx. diam. 50 mm, approx. length 350 mm) graduated 500 ml volume with rubber bungs or stirrer Stirrer and rod Glass weighing vessels (with masses known to 0.0001 g) Mechanical shaker (30 – 60 revolutions/min) Sieves (2 mm – 63 μm) Balance (accuracy 0.0001 g) Drying oven Stopwatch (accuracy 1 s) Glass filter funnel capable of holding the 63 μm sieve Wash bottle Desiccator 650 ml glass beaker with cover glass, 100 ml measuring cylinder, 25 ml pipette Hot plate or bunsen burner Electrical conductivity meter (accuracy 0.1 dS/m) Optional: Centrifuge and 300 ml centrifuge bottle
IV. Reagents
Hydrogen peroxide (H2O2), 30% volume fraction. Dispersing agent: 3.3 % sodium hexametaphosphate and 0.7 % soda solution: Dissolve 33 g sodium hexametaphosphate (NaPO3)6 and 7 g soda (Na2CO3) in water in a 1 l volumetric flask and make to volume. Both chemicals should be dried overnight at 105 °C prior to use. This solution is unstable and shall be replaced after one month. Antifoaming agent (preferably octan-2-ol, alternatives are ethanol or methanol)
Calcium chloride solution (CaCl2), conc. 1 mol/l Hydrochloric acid (HCl), conc. 1 mol/l
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V. Procedure
Test sample Depending on the soil type, weigh 10 (clay) to 30 g (sand) air-dried soil (fraction < 2 mm). Place the sample in the 650 ml glass beaker or 300 ml centrifuge bottle.
Destruction of organic matter Add 30 ml water to the test sample (add if necessary a few drops of octan-2-ol to allow thoroughly wetting). Add 30 ml of the 30 % hydrogen peroxide solution and mix using the glass or plastic rod (add if necessary a few drops of octan-2-ol to control foaming). Cover and leave overnight. The next day, place the vessel on a hot plate or bunsen burner and warm. Control foaming with octan- 2-ol and stir frequently. To avoid drying out, add water if necessary. Bring the suspension to a gentle boil until all signs of bubbling due to the decomposition of hydrogen peroxide have ceased. If undecomposed organic material is still present, cool the beaker and repeat the treatment with hydrogen peroxide. If using a centrifuge bring the volume to 150 – 200 ml by addition of water. Centrifuge the bottle until obtaining a clear supernatant (recommended 15 min at a minimum relative centrifugal force (RCF) of 400 g) and remove this supernatant by decanting or by using a suction device. If a centrifuge is not available the mineral residues may be flocculated by adding 25 ml of 1 mol/l calcium chloride solution, stirring and bringing to about 250 ml with water. Let stand until the supernatant is clear, then siphon or decant this from the residue. Add another 250 ml of water and repeat the washing procedure until the dark residues of the decomposed organic matter have gone (if using this method, take care to check the electrical conductivity (next step) before adding the salt).
Removal of soluble salts and gypsum After destruction of organic matter add water until obtaining a soil:water ratio of 1:4 – 1:6 (v:v). Shake for 1 h using a shaking machine. Centrifuge to obtain a clear supernatant and measure electrical conductivity (Ec) on this supernatant. If Ec > 0.4 dS/m soluble salts and gypsum is present in considerable amounts and have to be removed. Remove the supernatant, add 250 ml water and shake for 1 h. Centrifuge and measure electrical conductivity again. Repeat this washing procedure until Ec < 0.4 dS/m.
Removal of carbonates A distinction is made on basis of the presence or absence of calcium carbonate: (1) Calcareous soils: pH(H2O) > 6.8 (2) Non-calcareous soils: pH(H2O) < 6.8 Where the carbonate content is greater than about 2 % mass fraction, add to the washed, centrifuged soil (above) 4 ml of 1 mol/l hydrochloric acid for each percent of carbonate, plus an excess of 25 ml of acid. Make up to about 250 ml with water, and place the suspension on the water bath at about 80 °C for 15 min, stirring the suspension from time to time. Leave the suspension to stand overnight. If the soil flocculates sufficiently to leave a perfectly clear supernatant, then this can be siphoned off or decanted, otherwise centrifugation and decantation will be necessary. Repeat the washing and decantation with water until the Ec of the supernatant is less than 0,4 dS/m. 48 www.icp-forests.org/Manual.htm
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If the carbonate content is less than about 2 % mass fraction, then only an initial 25 ml of 1 mol/l hydrochloric acid solution is required. It is recommended, therefore, that 20 ml of 1 mol/l calcium chloride solution is added at the same time as the acid. The rest of the procedure is identical as for a higher carbonate content.
Note: if the carbonate content is that high that the results of the particle size distribution become unreliable, this should be mentioned in the Data Accompanying Report.
Dispersion Add sufficient water to the vessel so that the total volume is between 150 ml and 200 ml, shake the contents until all the soil is in suspension, and add 25 ml of dispersing agent from a pipette. Shake the bottle for 18 h on the end-over-end shaker.
Wet sieving at 63 μm Place a 63 μm aperture sieve in the large glass funnel, and place the funnel in the stand so that the neck of the funnel is inside one of the 500 ml sedimentation tubes. Transfer the dispersed suspension from the centrifuge bottle quantitatively onto the sieve, and wash the soil using a jet of water from the wash-bottle until the water runs clear. The total volume of the washings should not exceed 500 ml. Remove the sieve from the funnel and wash the residue on the sieve into an evaporating dish by means of a gentle spray from the wash-bottle. To alleviate sieve blockage, use the glass or plastic rod and rubber sleeve. Place this dish in an oven between 105 °C and 110 °C until the residue is dry. Record the mass to 0.0001 g (mfs). Wash any particles adhering to the inside of the funnel into the sedimentation tube. Make up the suspension in the sedimentation tube to 500 ml with water.
Calibration Calibration sampling pipette Clean and dry the pipette thoroughly and immerse the tip in water. Draw water into the pipette into the safety bulb. Drain off the water in the safety bulb through the outlet tube. Drain the pipette into a weighing bottle of known mass, and determine the internal volume of the pipette. Repeat this exercise three times and take the average of the three volumes as the internal volume of the pipette to the nearest 0.05 ml ( Vc ml). Calibration dispersing agent Pipette 25 ml of dispersing agent solution into one of the glass sedimentation tubes, and fill the tube to the 500 ml mark with water. Mix the contents of the tube thoroughly. Place the tube in the constant temperature environment, and leave the tube for at least 1 h. Between any of the times at which samples may be taken from the sampling tube (Table SA03-1), take a sample (Vc ml) of the dispersing agent solution from the sedimentation tube using the sampling pipette. Drain the pipette into a weighing vessel of known mass, and dry the contents of the vessel between 105 °C and 110 °C. Allow the vessel to cool in the desiccator and determine the mass of the residue in the vessel to 0.0001 g (mr). Follow this procedure each time a new batch of dispersing agent is prepared.
Sedimentation Place the sedimentation tube in the constant temperature environment. Agitate (at least 30 times/min for a minimum of 2 min ) the contents of the sedimentation tube vigorously, either by version 5/2010 49
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means of the stirrer, or by inserting a bung in the tube, followed by end-over-end shaking. Replace the tube upright in the constant-temperature environment and start the timer. About 15 s before a sample is to be taken (Table SA03-1), lower the pipette, with the tap of the safety bulb closed, vertically into the soil suspension, and centrally in the sedimentation tube, until the tip is the appropriate depth (± 1 mm) below the suspension surface (Table SA03-1). Take care to disturb the suspension as little as possible, and complete the operation within about 10 s. Open the tap of the safety bulb and withdraw a sample of the suspension such that the pipette and a part of the safety bulb are full. This sampling operation shall take about 10 s. Withdraw the pipette from the suspension so that the tip of the pipette is clear of the top of the sedimentation tube. Run the surplus present in the safety bulb into a small beaker by the outlet tube. Wash with water from the water reservoir until no suspension remains in this part of the system. Place a weighing vessel of known mass (to 0.0001 g) under the tip of the pipette and open the tap so that the contents of the pipette are delivered to the vessel. Wash any suspension left on the inner walls of the pipette into the vessel by allowing water from the water reservoir to run through the system. Place the weighing vessel and contents in the oven between 105 °C and 110 °C, and evaporate to dryness. Cool the vessel in the desiccator, weigh the vessel and its contents to the nearest 0.0001 g, and determine the mass of the residue the nearest 0.0001 g (ms1). Clean the outside of the pipette of any adhering sediment, and take the other sample (fraction < 2 μm), in accordance with the times given in Table SA03-1, using the same pipetting procedure given above. Call the additional sample masse ms2.
Table SA03-1: Pipette sampling times and fraction at different temperatures Temperature (°C) Time (after mixing) of starting sampling operation Fraction : < 63 µm Fraction : < 2 µm Sampling depth 200 mm ± 1 mm Sampling depth 100 mm ± 1 mm 20 56 s 7 h 44 min 16 s 21 54 s 7 h 34 min 04 s 22 53 s 7 h 23 min 53 s 23 52 s 7 h 13 min 13 s 24 51 s 7 h 03 min 02 s 25 49 s 6 h 52 min 50 s 26 48 s 6 h 44 min 02 s 27 47 s 6 h 35 min 42 s 28 46 s 6 h 26 min 53 s 29 45 s 6 h 18 min 33 s 30 44 s 6 h 09 min 45 s
VI. Calculation
Fractions < 63 μm Calculate the mass of solids in suspension in 500 ml (mf1 , mf2) in grams, for each pipette sampling time from the equation:
Mass < 63 μm in 500 ml : mf1 = ms1 (500/Vc) Mass < 2 μm in 500 ml : mf2 = ms2 (500/Vc)
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where: mfx is the mass (g) of solid in suspension in 500 ml; msx is the mass (g) of material from the xth pipette sampling; Vc is the calibrated volume of the pipette.
Each fraction however, still contains a part of dispersing agent, which has to be corrected. The mass of solid material in 500 ml of dispersant solution, md, in grams, is given by:
Mass dispersing agent in 500 ml: md = mr (500/Vc) where: mr is the mass of residue, in grams; Vc is the calibrated volume of the pipette, in millilitres. This gives the final fraction masses:
Clay Mass fraction < 2 μm = mf2 - md Silt Mass fraction 2 – 63 μm = mf1 - mf2
Fraction 63 μm - 2 mm Mass of the fraction 63 μm - 2 mm = mfs
Proportion of fraction The method of calculation assumes that the sample mass is the sum of the constituent fractions, and not the mass of the test sample. The mass of sample < 2 mm is thus the sum of the masses of the fractions obtained by wet sieving at 63 μm and the masses of the fractions obtained by calculation. Denote this total sample mass as mt in grams. Calculate the proportion in each fraction <2 mm as follows:
Proportions = mass of fraction/mt
VII. Report
It is an agreed convention that the percentage of each particle size grade is reported on the basis of oven-dry soil free of organic matter (1 decimal place). Note: With this calculation, the clay, silt and sand fractions are obtained in percentage of the sum of the constituent fractions (after removal of carbonates and organic matter).
USDA-FAO texture classification is based on the USDA-FAO textural triangle (FAO, 1990) as shown in Figure 1.
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VIII. References
ISO 11277. 1998. Soil Quality – Determination of particle size distribution in mineral soil material – Method by sieving and sedimentation. International Organization for Standardization. Geneva, Switzerland. 30 p. (available at www.iso.ch) FAO. 1990. Guidelines for soil description, 3rd (revised) edition.
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Soil Analysis Method 4 (SA04): Determination of Bulk Density
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Bulk Density Method sheet SA04 Reference methods ISO 11272 Method suitable for Mineral Layer
I. Relevance in ICP Forests
Priority Level I Level II Organic Layer - - Mineral layer 0 – 10 cm Mandatory1,2,3 Mandatory2,3 10 – 20 cm Mandatory1,2,3 Mandatory2,3 20 – 40 cm Mandatory1,2,3 Mandatory2,3 40 – 80 cm Optional Optional
1 may also be obtained by using pedo-transfer functions 2 only mandatory in non-stony soils 3 in case of re-assessment (if the parameter was already measured according to the reference method in a previous survey, the measurement is optional
II. Principle
The dry bulk density (BD) is the ratio between the mass of oven dry soil material and the volume of the undisturbed fresh sample. The ISO defines dry bulk density as the ratio of the oven-dry mass of the solids to the volume (the bulk volume includes the volume of the solids and of the pore space) of the soil. Non-gravely soils (when coarse fragments content < 5%) Several methods can be applied for the determination of bulk density, going from simple methods such as digging out holes of known volume to sophisticated gamma radiometry methods. The recommended method (core method) uses steel cylinders of known volume (100 cm3, 400 cm3) that are driven in the soil vertically or horizontally by percussion. Sampling large volumes results in smaller relative errors but requires heavy equipment. The method cannot be used if stones or large roots are present or when the soil is too dry or too hard. Soils with high stone or root content or when the soil is too dry or too hard In these conditions it is advised to use measuring methods based on the following principle (excavation method): a hole on a horizontal surface is dug and then filled with a material with a known density (e.g. sand which packs to a calibrated volume or water separated from the soil material by an elastic membrane). The obtained soil from the hole, is dried to remove the water and the dry mass is weighed. Methods measuring the volume of clods or aggregates should be avoided because they tend to underestimate macroporosity. The volumetric percentage of the coarse fragments needs to be determined in order to calculate the bulk density of the fine earth. Stony soils
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Soils with a high content of gravel (0.2 – 6 cm) and/or the presence of stones (6 – 20 cm) and boulders (> 20 cm), have a low volume of fine earth. Core samplers normally used in forest monitoring are not able to representatively collect stones or large portions of coarse fragments in the field. In these cases, the above recommended excavation method will produce good results but may be considered very expensive, time-consuming and destructive. So, alternatively, a combined approach is described where the quantity of bulk density of both fine earth and coarse fragments (SA05) has to be estimated / sampled in the field. Methods are according to the prevailing conditions (i.e. coarse fragment content and size) at each individual sampling site: In case of coarse fragment content of more than 5 %, the fine earth fraction must be sieved and weighed. Its volume must then be determined either directly or indirectly by establishing the coarse fragment volume. Furthermore, the density of the coarse fragments (specific weight) must be known or established. In case of content of coarse fragments > 20 mm, representative sampling is no longer possible with a core sampler. Then the coarse fragment content must be determined by additional sampling using a shovel or spade and/or estimations in the soil profile. In case of coarse fragments content of > 60 mm, representative volume sampling is not possible and sampling with mini-core samplers is combined with an estimation in the profile pit. In the analysis each method or each combined method leads to the determination of (partially) different parameters which means that different calculation formulas are needed. Note: The determination of the bulk density of the fine earth is incorrect when the sample contains significant portions of roots in addition to the coarse fragment portions. In these cases, this must be corrected.
III. Apparatus
Core sample holders, thin-walled metal cylinders with a volume of 100 cm3 to 400 cm3, a steel cap for driving into the soil, and a driver (or root auger, hollow stem auger, AMS core sampler with liner or alike) Oven (heated and ventilated, temperature 105 ± 2 °C) Desiccator Balance (accuracy 1/1000 of measured value). Spade, shovel Metal sieves (2 mm, 20 mm, 60 mm)
IV. Reagents
No reagents.
V. Procedure
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Press or drive a core sample holder of known volume without deflection and compaction into either a vertical or horizontal soil surface far enough to fill the sampler. Carefully remove the sample holder and its contents to preserve the natural structure, and trim the soil extending beyond each end of the sample holder with a straight-edged knife or sharp spatula. The soil sample volume is thus equal to the volume of the sample holder. Take at least five core samples from each soil layer. Place the holders containing the samples in an oven at 105 °C until constant mass is reached (minimum 48 h). Remove the samples from the oven and allow them to cool in the desiccator. Weigh the samples on the balance immediately after removal from the desiccator (mt). Control mass is reached when the differences in successive weighings of the cooled sample, at intervals of 4 h, do not exceed 0,01% of the original mass of the sample.
Case 2: Mineral soil with a coarse fragment content of more than 5% that can be sampled with a core sampler or any other representative sampler (coarse fragments < 20 mm) The mineral soil sample is collected in the field with core samplers from the undisturbed soil. In the laboratory the sample is then dried at a temperature of 105 °C for at least 48 hours to constant mass and weighed. The sample is then passed through a 2 mm metal sieve and the sieve residue washed in order to break down clumpy fine earth material and to rinse off earth adhering to the stones. The washed sieve residue (= coarse fragment portion) is shaken into a beaker, dried at a temperature of 105°C in a drying oven and then weighed.
Case 3: Mineral soil, which cannot be sampled with a core sampler or any other representative sampler (coarse fragments > 20 mm) Case 3.1.: Combination of representative volume sampling with a core sampler and estimation of coarse fragments > 20 mm The mineral soil sample is collected in the field with core samplers from the undisturbed soil. In the laboratory the sample is dried at a temperature of 105 °C for at least 48 hours to constant mass and weighed. The sample is passed through a 2 mm metal sieve and the sieve residue washed in order to break down clumpy fine earth material and to rinse off earth adhering to the stones. The washed sieve residue (= coarse fragment portion) is shaken into a beaker, dried at a temperature of 105 °C in a drying oven and then weighed. After that, the sieve residue is passed through a 20 mm sieve and the 2 – 20 mm sieve fraction (fine and medium gravel) weighed. For the coarse fragment portion > 20 mm an estimation from the profile description must be available. Case 3.2.: Combination of representative volume sampling with a core sampler, disturbed sample and estimation of coarse fragments more than 60 mm at the profile The mineral soil sample is collected in the field with a core sampler from the undisturbed soil. In addition, a larger sample volume, which must be representative for the coarse fragment fraction 2 – 60 mm (gravel), is collected with a shovel or a spade. In the laboratory the two samples are then dried at a temperature of 105 °C for at least 48 hours to constant mass and weighed. The core sample is then passed through a 2 mm metal sieve and the sieve residue is washed in order to break down clumpy fine earth material and wash off earth adhering to the stones. The washed sieve residue (= coarse fragment portion) is shaken into a beaker, dried in a drying oven at a temperature of 105 °C and then weighed. The spade sample is also dried at a temperature of 105 °C to constant mass and then weighed. The spade sample is then passed through a 2 mm sieve and the sieve residue through a 60 mm sieve. The coarse fragment fraction 2 – 60 mm obtained in this way is weighed. For the coarse fragment content > 60 mm an estimation from the profile description must be available.
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Case 4: Representative volume sampling not possible, Sampling with mini-core samplers With core sampler caps or mini-core samplers (n ≥ 5) several samples are taken from the undisturbed soil. In addition, a larger sample volume, which must be representative for the coarse fragment fraction 2 – 60 mm, is collected with a shovel or a spade. In the laboratory the core sampler caps together with their contents are dried at a temperature of 105 °C for at least 48 hours to constant mass and then weighed together. The empty mass of the core sampler caps is then deducted from the total mass. The spade sample is dried at a temperature of 105 °C for at least 48 hours to constant mass and then weighed. The sample is then passed through a 2 mm sieve and the sieve residue through a 6 mm sieve. The sieve residue is then passed through a 60 mm sieve as well. The fractions obtained < 2 mm (fine earth), 2 – 6 mm (fine gravel) and 6 – 60 mm (medium and coarse gravel) are weighed. Alternative to the combined approach of case 2 till case 4 in soils with high stone or root content or if the soil is too dry or too hard In case of gravely or stony soils an alternative excavation method consist of excavating a quantity of soil, drying and weighing it, and determining the volume of the excavation by filling it with sand (cf. ISO 11272 – excavation method). Note that the excavation method measures the total dry bulk density
VI. Calculation
Case 1: Non-gravely soils (when coarse fragments content < 5%)
In case of measurements, the bulk density of the fine earth (BDfe) is approximately equal to the bulk density of total soil. The bulk density (BDs) the for non-gravely soils is calculated as follows: M == s s BDBD fe (equation SA04.01) Vs where: 3 BDs = Bulk Density of the sample (kg/m ) 3 BDfe = Bulk Density of the fine earth (kg/m ) Ms = Dry Mass of the sample (kg) 3 Vs = Volume of the sample (m ) Case 2: Mineral soil with a coarse fragment content of more than 5% that can be sampled with a core sampler or any other representative sampler (coarse fragments < 20 mm) In case of measurement with a core sampler, the bulk density of the fine earth of gravely soils (BDfe) is calculated as follows: M _ MM − MM BD = fe = cfs = cfs (equation SA04.02) fe V −VV M fe cfs V − cf s ρ cf where: 3 BDfe = Bulk density of the fine earth (kg/m ) Mfe = Dry Mass of the fine earth taken with core sampler (kg) 3 Vfe = Volume of the undisturbed fine earth (m ) Ms = Dry Mass of the soil sample with gravel taken with core sampler (kg) Mcf = Dry Mass of the coarse fragments taken with the core sampler (kg) version 5/2010 57
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3 Vs = Volume of core sampler (m ) Vcf = Volume of the coarse fragments taken with the core sampler (kg) 3 ρcf = Density of the coarse fragments (approximated by 2650 kg/m ) The fine earth stock (FES) is the amount (kg) of fine earth in the soil layer under consideration expressed per ha. In stony soils, a correction for the volume of coarse fragments is required. It is calculated as follows: ⎛ V ⎞ ⎛ M ⎞ dBDFES ⎜110 −×××= cf ⎟ dBD ⎜110 −×××= cf ⎟ (equation SA04.03) fe ⎜ ⎟ fe ⎜ ρ × ⎟ ⎝ Vs ⎠ ⎝ Vscf ⎠ where: FES = Fine earth stock (t/ha) 3 BDfe = Bulk density of fine earth (kg/m ) d = Thickness of the sampled layer (m) Vscf = Volume of coarse fragment taken with core sampler (respectively core of root auger) (m3) Mcf = Dry Mass of coarse fragment taken with core sampler (respectively core of root auger) (kg) 3 ρcf = Density of the coarse fragments (approximated by 2650 kg/m ) 3 Vs = Volume of core sampler (m ) Notes: If the core sampler sample cakes strongly as a consequence of drying, it might make sense to pulverise the sample with a crusher prior to sieving. The big stones should be removed beforehand. . In the case of non-cohesive soil (sand), there is no need to wash or dry the stones.
Case 3: Mineral soil, which cannot be sampled with a core sampler or any other representative sampler (coarse fragments > 20 mm) Case 3.1. Combination of representative volume sampling with a core sampler and estimation of coarse fragments > 20 mm
The bulk density of the fine earth (BDfe) is calculated using equation SA04.02. The FES is calculated as follows:
⎛ > MV − ⎞ dBDFES ⎜110 cf 20 −−×××= cf )202( ⎟ (equation SA04.04) fe ⎜ ρ × ⎟ ⎝ 100 Vscf ⎠ where: FES = Fine earth stock (t/ha) 3 BDfe = Bulk density of fine earth (kg/m ) d = Thickness of the sampled layer (m) Mcf(2-20) = Dry Mass of coarse fragment between 2 and 20 mm taken with core sampler (respectively core of root auger) (kg) Vcf>20 = Percentage volume of coarse fragment of the fraction > 20 mm estimated at the profile (%) 3 ρcf = Density of the coarse fragments (approximated by 2650 kg/m ) 3 Vs = Volume of core sampler (m ) Notes: see Case 2
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Case 3.2. Combination of representative volume sampling with a core sampler, disturbed sample and estimation of coarse fragments more than 60 mm at the profile The bulk density of the fine earth (BDfe) is calculated using equation SA04.02. The fine earth stock (FES) is calculated as follows: ⎛ ⎞ ⎜ ⎟ ⎜ MV BD ⎟ cf >60 −−×××= ds − )602( × fe fe dBDFES ⎜110 ⎟ 100 BD M − ⎜ cf MM BD ×+− ds )602( ⎟ ⎜ ds ds − )602( fe ρ ⎟ ⎝ cf ⎠ (equation SA04.05) where: FES = Fine earth stock (t/ha) 3 BDfe = Bulk density of fine earth (kg/m ) d = Thickness of the sampled layer (m) Mds(2-60) = Dry Mass of coarse fragment between 2 and 60 mm of the disturbed sample (kg) Vcf>60 = Percentage volume of coarse fragment > 60 mm estimated at the profile (%) 3 ρcf = Bulk density of the coarse fragments (approximated by 2650 kg/m ) Mds = Total dry mass of the disturbed sample (kg) Notes: see Case 2 Case 4: Representative volume sampling not possible, Sampling with mini-core samplers From the mass of the sample < 6 mm and the mass of the coarse fragment fraction 2 mm – 6 mm, factor f, which is approximately the coarse fragment portion in the core sampler cap, is calculated as follows:
M − f = ds )62( (equation SA04.06) M ds < )6( where: Mds(2-6) = Mass of coarse fragment of the fraction 2 - 6 mm of the disturbed sample (kg) Mds(<6) = Mass of the sample < 6 mm in the aliquot of the disturbed sample (kg) For the coarse fragment content > 60 mm an estimation from the profile must be available.
The bulk density of the fine earth (BDfe) is calculated using the following formula: MINIM × ()1− f BD = TOT (equation SA04.07) fe × fMINIM MINIV − TOT TOT ρ cf where: MTOTMINI = Mass of mini-core sampler (kg) 3 VTOTMINI = Volume of mini-core sampler (m ) 3 3 ρcf = Density of the coarse fragments (kg/m ) (approximated by 2650 kg/m ) The fine earth stock (FES) is calculated using equation SA04.05.
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VII. Report
The dry bulk density (BD) is recorded in kg/m3 with no decimal places. In the case of stony or gravely soils the bulk density of the fine earth fraction (< 2 mm) should be reported together with the coarse fragment content (vol %) (See also SA05).
Furthermore, the bulk density of the coarse fragments should be known, but this may be approximated as 2650 kg.m-3. In the case that pedotransfer functions are used (Level I), the calculation procedure should be reported as well. Note that the “excavation method” described in ISO11272, asks for the total dry bulk density of the soil, while in this programme the bulk density of the fine earth should be reported.
VIII. Reference
ISO 11272. 1993. Soil Quality – Determination of dry bulk density. International Organization for Standardization. Geneva, Switzerland. 10 p. (available at www.iso.ch) DIN ISO 11272, Normenausschuß Wasserwesen (NAW) in the Dt. Inst. für Normung e.V. [Eds.] (2001): Bodenbeschaffenheit - Bestimmung der Trockenrohdichte (Soil composition, Determination of bulk density) W. Riek, B. Wolff (2006): Evaluierung von Verfahren zur Erfassung des Grobbodenanteils von Waldböden – Erarbeitung von Empfehlungen für die Anwendung dieser Verfahren im Rahmen der Bodenzustandserhebung im Wald (BZE II)“. Eberswalde (Evaluation of methods to determine the coarse fragment portion of forest soils – Drawing up recommendations for the use of these methods in forest soil surveys)
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Soil Analysis Method 5 (SA05): Determination of Coarse Fragments
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Coarse Fragments Method sheet SA05 Reference methods ISO 11464, ISO 11277 Method suitable for Mineral horizons
I. Relevance in ICP Forests
Priority Level I Level II Organic Layer - - Mineral layer 0 – 10 cm Mandatory1,2 Mandatory 10 – 20 cm Mandatory1,2 Mandatory1,2 20 – 40 cm Mandatory1,2 Mandatory1,2 40 – 80 cm Optional1 Optional1 1 may be obtained by estimation 2 in case of re-assessment (if the parameter was already measured according to the reference method in a previous survey), the measurement is optional
II. Principle
The abundance of coarse fragments can be measured in the laboratory, but is usually estimated during routine soil profile description (see Annex 2). When the estimation is based on such a visual observation, one should take into account the volume of the macropores (packing pores between the stones) which is often underestimated. The most straightforward way to determine the volumes in the field of stones and boulders is by digging pits. This method, however, encounters practical problems such as hard manual work and destructive sampling. The 'Finnish method' or 'rod penetration method' is described here as an example of a non-destructive method. This method estimates the proportion (volume %) of coarse gravel (2 – 6 cm), stones (6 – 20 cm) and boulders (> 20 cm) in the 0 – 30 cm mineral layer by pushing a graduated metal rod down through the organic layer and as far as possible into the mineral soil. Coarse fragments are separated from the fine earth fraction during the preparation of soil samples (SA01). The content of coarse fragments, cf. (mass %), is determined by weighing the residue left on a 2 mm sieve after washing and drying in the laboratory.
III. Apparatus
Field estimation: The 'Finnish method' or 'rod penetration method' graduated metal rod (diameter 10 mm, length 80 – 100 cm)
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Laboratory measurement No apparatus, using data obtained in preparation of soil sample (SA01).
IV. Reagents
Field estimation: The 'Finnish method' or 'rod penetration method' No reagents. Laboratory measurement No reagents, using data obtained in preparation of soil sample (SA01).
V. Procedure
Field estimation: The 'Finnish method' or 'rod penetration method' The volume of stones is estimated in the 0-30 cm mineral soil layer. A steel rod (d = 10 mm, length = 80…100 cm, with a tip of hard metal, gradation lines at 10 cm intervals, see Fig. 1) is pushed down (through the organic layer) into the mineral soil with sufficient force that the rod will stop if it comes into contact with a stone of 2 cm or larger (moderate push). The measuring rod is pushed down into the mineral soil at e.g. 20 or 30 systematically located (using a tape measure or even paces) points. The depth of penetration is measured with respect to the surface of the ground. If there is an organic layer present, then its thickness has to be measured using the rod or by taking a sample of the organic layer and measuring its thickness, and then subtracted from the penetration depth. In Finland, penetration is measured and organic layer samples are taken at the same time. The average penetration value and stoniness of the 0-30 cm mineral soil layer is calculated as follows (only 5 points in this example):
Penetration depth Organic layer Penetration depth – organic Penetration in the (cm) thickness (cm) layer thickness (cm) ≤30 layer (cm) 12 2 10 10 40 4 36 30 4 4 0 0 35 3 32 30 22 5 17 17 Average = 17.4
The great advantage of the rod method is that a large number of measurements can be made easily and quickly over the whole plot. The inaccuracy and other drawbacks of the method outweigh the lack of representability involved in measuring (estimating) stoniness in a very restricted number of soil pits.
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FIGURE 2: TIP OF THE PENETRATION ROD
FIGURE 1: PENETRATION ROD
Laboratory measurement No procedure, using data obtained in preparation of soil sample (SA01).
VI. Calculation
Field estimation 0 – 30 cm layer Volume of stones (%) = 83 - 2.75 * average penetration (cm) [Equation SA05.01] The volume of stones in the example = 83 - 2.75 * 17.4 = 35 % in the 0-30 cm layer. According to equation SA05.01, the volume of stones is 0.5 % when the average penetration into the mineral soil is 30 cm, and volume of stones is 83 % when the average penetration is 0 cm. It is possible to estimate the stoniness of thinner layers if the empirical relationship between penetration depth and volumetric stone percentage remains the same. The relevant equations are as follows: 0-10 cm layer Volume of stones (%) = 83 - 8.25 * average penetration (cm) for the layer
0-20 cm layer Volume of stones (%) = 83 - 4.125 * average penetration (cm) for the layer.
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The constant maximum depth of each penetration should be set so that it reaches the target mineral soil depth, i.e. 30, 20 or 10 cm, through the thickest possible organic layer. On upland soils an extra 10 cm is commonly added to the target depth, i.e. there is a target depth of 40 cm if the studied layer is 0-30 cm, or to 30 cm if the layer is 0-20 cm. Note: Equation SA05.01 is based on a very specific material [Finnish till (morainic) soils] but has not been tested on other soils, and in some respects it is somewhat illogical (see Eriksson and Holmgren, 1996). It is therefore of utmost importance that the equation is calibrated locally before it can be applied on other soil types.. Laboratory measurement The content of coarse fragments, cf (mass%), is determined by weighing the residue left on a 2 mm sieve after washing and drying according to: soilofmass ___ fraction > 2mm masscf %)( = x100 ______soildryoventotaltheofmass In order to convert the content by mass to an expression by volume, the bulk density of both the coarse fragments and the fine earth should be determined. BDs volcf %)( = masscf %)(* BDcf
where: 3 BDs = Bulk density of the total soil (kg/m ) 3 BDcf = Bulk density of the coarse fragments (approximated by 2650 kg/m ) cf(vol%) = Volumetric percentage of coarse fragments in the soil (%) cf(mass%) = Mass percentage of coarse fragments in the soil (%)
VII. Report
The amount of coarse fragments (stones and gravel with a diameter > 2 mm) has to be reported for the individual mineral layers in volume % without decimals.
Note: The Rod penetration method only allows reporting for the 0 – 10 cm, 0 – 20 cm or 0- 30 cm layer and for the coarse fragments > 2 cm
VIII. References
Eriksson, C.P., Holmgren, P. 1996. Estimating stone and boulder content in forest soils – evaluating the potential of surface penetration methods. Catena 28: 121 – 134. ISO 11464. 1994. Soil Quality – Pretreatment of samples for physico-chemical analysis. International Organization for Standardization. Geneva, Switzerland. 9 p. (available at www.iso.ch) ISO 11277. 1998. Soil Quality – Determination of particle size distribution in mineral soil material – Method by sieving and sedimentation. International Organization for Standardization. Geneva, Switzerland. 30 p. (available at www.iso.ch) version 5/2010 65
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Mikkelsen, J. Cools, N., Langohr, R. 2006 Guidelines for Forest Soil Profile Description, adapted for optimal field observations within the framework of the EU Forest Focus Demonstration Project. BIOSOIL. Partly based on the 4th edition of the Guidelines for Soil Profile Description and Classification (FAO, 2006). Tamminen, P. 1991. Kangasmaan ravinntunnusten ilmaiseminen ja viljavuuden alueellinen vaihtelu Etelä-Suomessa. Summary: Expression of soil nutrient status and regional variation in soil fertility of forested sites in Southern Finland. Folia Forestalia 777: 1-40. Viro, P., 1947. Metsämaan raekoostumus ja viljavuus varsinkin maan kivisyyttä silmällä pitäen. Summary: The mechanical composition and fertility of forest soil taking into consideration especially the stoniness of the soil. Communicationes Instituti Forestalis Fenniae 35, 115. - 1952. Kivisyyden määrittämisestä. Summary: On the determination of stoniness. Communicationes Instituti Forestalis Fenniae 40, 23. - 1958. Suomen metsämaiden kivisyydestä. Summary: Stoniness of forest soil in Finland. Communicationes Instituti Forestalis Fenniae 49, 45
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551 Sampling and Analysis of Soil Part X
Soil Analysis Method 6 (SA06): Determination of Soil pH
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pH Method sheet SA06 Reference methods ISO 10390 Method suitable for Organic Layer; Mineral Layer
I. Relevance in ICP Forests pH(CaCl2)
Priority Level I Level II Organic Layer OL - - OF+OH, H-layers Mandatory Mandatory Mineral layer 0 – 10 cm Mandatory Mandatory 10 – 20 cm Mandatory Mandatory 20 – 40 cm Optional Mandatory2 40 – 80 cm Optional Mandatory2 2 in case of re-assessment (if the parameter was already measured according to the reference method in a previous survey), the measurement is optional
pH(H2O)
Priority Level I Level II Organic Layer Optional Optional OL - - OF+OH, H-layers Optional Optional Mineral layer 0 – 10 cm Optional Optional 10 – 20 cm Optional Optional 20 – 40 cm Optional Optional 40 – 80 cm Optional Optional
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II. Principle
The pH of the soil is potentiometrically measured in the supernatant suspension of 1:5 (volume fraction). This liquid is made up of a 0.01 mol/l solution of calcium chloride in water for pH(CaCl2) or deionised water for pH(H2O).
III. Apparatus
End-over-end shaking machine pH meter with appropriate electrode Thermometer (accuracy 1 °C) Sample bottle (capacity at least 50 ml) with cap Accurate measuring spoon
IV. Reagents
Water (grade 2)
Calcium chloride (CaCl2), conc. 0.01 mol/l
make a solution of 1.47 g CaCl2.2H2O/liter water pH buffer solutions
V. Procedure
Preparation of the suspension Take a representative sample (at least a volume of 5 ml) of the air-dried soil (fraction < 2 mm) using the accurate measuring spoon. Place the test sample in the sample bottle and add five times its volume of calcium chloride solution (pH-CaCl2) or deionised water (pH-H2O). Shake or mix the suspension for 60 min +/- 10 min, using the mechanical shaker or mixer, and wait for at least for 1 hour before measuring but not longer than 3 hours. Ingres of air during standing after shaking should be avoided. Calibration of pH meter Calibrate the pH-meter as prescribed in the manufacturer’ s manual, using the buffer solutions. pH measurement Measure the pH in the suspension at 20°C ± 2°C immediately after or whilst being stirred. The stirring should be at such a rate to achieve a reasonable homogeneous suspension of the soil particles, but entrainment of air should be avoided. Read the pH after stabilisation of the value is reached.
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VI. Calculations
No calculations.
VII. Report
Note the recorded values to two decimal places.
VIII. Reference
ISO 10390. 2005. Soil Quality – Determination of pH. International Organization for Standardization. Geneva, Switzerland. 5 p. (available at www.iso.ch)
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555 Sampling and Analysis of Soil Part X
Soil Analysis Method 7 (SA07): Determination of Carbonate Content
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Carbonates Method sheet SA07 Reference methods ISO 10693 Method suitable for Organic Layer, Mineral Layer
I. Relevance in ICP Forests
Priority Level I Level II Organic Layer OL - - OF+OH, H-layers Mandatory1 Mandatory1 Mineral layer 0 – 10 cm Mandatory1 Mandatory1 10 – 20 cm Mandatory1 Mandatory1 20 – 40 cm Optional Optional 40 – 80 cm Optional Optional 1 Only mandatory if pH(CaCl2) > 5.5 or in calcareous soils
II. Principle
The soil sample is treated with a strong acid. The volume of the carbon dioxide produced is measured by using a calcimeter (Scheibler unit), and is compared with the volume of carbon dioxide produced by pure calcium carbonate.
III. Apparatus
Calcimeter (Scheibler unit) Analytical balance (accuracy 0.0001 g) Reaction vessels (capacity 150 ml) Plastic cups (which can pass through the neck of the reaction vessel) Tong Watch glass
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IV. Reagents
Distilled water Hydrochloric acid (HCl), conc. 4 mol/l Dilute 340 ml of concentrated hydrochloric acid ( = 1.19 g/ml) to 1000 ml with water.
Calcium carbonate (CaCO3), pure.
V. Procedure
Preparation The mass of the test portion is determined based on the carbonate content. For a preliminary test on carbonate content, add some hydrochloric acid to a portion of the soil on a watch glass. The carbonate content of the sample can be estimated on the basis of the intensity and duration of effervescence (Table SA07-1). Determine from table SA07-1 the mass of test portion (air-dried soil fraction < 2 mm).
Table SA07-1: Mass of test portion for determination of carbonate content based on intensity of effervescence
Intensity of effervescence Carbonate content (g/kg) Mass of test sample (g) None or only limited < 20 10 Clear, but for a short time 20 – 80 5 Strong, for a long time 80 – 160 2.5 Very strong, for a long time > 160 11 1 use sample that is crushed to a particle size of less than 250 µm
Measurement Transfer the sample into the reaction vessels and add 20 ml of water. Fill the plastic cup with 7 ml of hydrochloric acid and place this, using tongs in the reaction vessel containing the test portion. Take care that there is no contact between the hydrochloric acid and the soil before the reaction vessel is connected to the calcimeter (Scheibler unit). Warm the reaction vessel by hand. Connect the reaction vessel to the calcimeter. Carefully add the hydrochloric acid from the cup to the soil by tilting the reaction vessel at an angle. The gas produced will lower the water level in the tube on the right and at the same time will raise the water level in the tube on the left. Shake for 5 min and note the volume when it no longer varies. If it still varies, continue shaking until the volume is stable, but not longer than 1 h. At the end of the shaking period, bring the water level in both tubes to the same height and measure the volume of gas in the calibrated tube with an accuracy of 0.1 ml. Calibration Determinations of samples, blanks and the calcium carbonate used as standard material, shall be performed simultaneously in a room where temperature and pressure do not vary too much during the measurement.
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Weigh the standards of 0.200 g and 0.400 g of calcium carbonate, transfer these amounts into the reaction vessels and add 20 ml of water. For the blank determinations, use reaction vessels containing 20 ml of water.
VI. Calculations
−VVm 312 )( w 3 1000)CaCO( ×= V-Vm 321 )(
w(CaCO3) = carbonate content of sample (g/kg) on basis of air dried soil m1 = mass (g) of test sample m2 = mean mass (g) of standards V1 = volume (ml) of CO2 produced by test sample V2 = mean volume (ml) of CO2 produced by standards V3 = volume change (ml) in blank determinations (can be negative)
VII. Report
The results of the carbonate (g/kg) must be reported without decimals on the basis of oven-dried soil.
VIII. Reference
ISO 10693. 1994. Soil Quality – Determination of carbonate content - Volumetric method. International Organization for Standardization. Geneva, Switzerland. 7 p. (available at www.iso.ch)
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559 Sampling and Analysis of Soil Part X
Soil Analysis Method 8 (SA08): Determination of Organic Carbon Content
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Organic Carbon Method sheet SA08 Reference methods ISO 10694 Method suitable for Organic Layer, Mineral Layer
I. Relevance in ICP Forests
Priority Level I Level II Organic Layer OL - - OF+OH, H-layers Mandatory Mandatory Mineral layer 0 – 10 cm Mandatory Mandatory 10 – 20 cm Mandatory Mandatory 20 – 40 cm Mandatory Mandatory 40 – 80 cm Optional Optional
II. Principle
The carbon present in the soil is oxidised to carbon dioxide (CO2) by heating the soil to at least 900 °C in a flow of oxygen-containing gas that is free from carbon dioxide. The amount of carbon dioxide released is then measured by titrimetry, gravimetry, conductometry, gas chromatography or using an infrared detection method, depending on the apparatus used. When the soil is heated to a temperature of at least 900 °C, any carbonates present are completely decomposed. Total organic carbon can be determined directly or indirectly. Direct determination consists of previous removal of any carbonates present by treating the soil with hydrochloric acid. Indirect determination consists of a correction of the total carbon content for the carbonates present.
III. Apparatus
Glassware Analytical balance (accuracy 0.0001 or 0.00001 g) Apparatus for determination of total carbon content (temperature at least 900 °C) Crucibles proper for the apparatus
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IV. Reagents
Combustion gas - chemicals and catalysts proper to the apparatus Calibration substances Hydrochloric acid (HCl), conc. 4 mol/l
V. Procedure
Laboratory sample Use sample of air-dried soil (fraction < 2 mm) of known moisture and carbonate content. Calibration of the apparatus Calibrate the apparatus as described in the relevant manual using the calibration substances. Direct determination of organic carbon content Add an excess of hydrochloric acid (4 mol/l) to the crucible containing a weighed quantity of air- dried soil and mix. Wait 4 h and dry the crucible for 16 h at a temperature of 60 °C to 70 °C. The amount of test portion taken for analysis depends on the expected carbon content and on the apparatus used. Weigh out m1 g of the air-dried sample in a crucible. Carry out the analyses in accordance with the manufacturer’s manual for the apparatus. Indirect determination of organic carbon content The procedure is identical to the direct determination of organic carbon content, without adding hydrochloric acid. The measured total carbon content is calculated according to the amount of test portion taken for analysis which depends on the expected total carbon content and on the apparatus used. Weigh out m1 g of the air-dried sample in a crucible. Carry out the analyses in accordance with the manufacturer’s manual for the apparatus.
VI. Calculation
Direct determination of organic carbon content The organic carbon content (on basis of air-dried soil) is obtained by :
m2 wC,o 1000 ××= 2727.0 m1 where wC,o = Organic carbon content (g/kg) on basis of air-dried soil m1 = Mass (g) of test portion m2 = Mass (g) of released CO2 0.2727 = Conversion factor for CO2 to C
Indirect determination of organic carbon content The total carbon content (on basis of air-dried soil) is obtained by :
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where wC,t = Total carbon content (g/kg) on basis of air-dried soil m1 = Mass (g) of test portion m2 = Mass (g) of released CO2 0.2727 = Conversion factor for CO2 to C
Calculate the organic carbon content of the sample using a correction for carbonates. The organic carbon content (on basis of air dried soil) is calculated by:
, = ww , tCoC − × wCaCO3)12.0( where wC,o = Organic carbon content (g/kg) on basis of air-dried soil wC,t = Total carbon content (g/kg) on basis of air-dried soil 0.12 = Conversion factor wCaCO3 = Carbonate content (g/kg) on basis of air-dried soil
VII. Report
Report organic carbon content (in g/kg) with 1 decimal place on the basis of oven-dried soil.
VII. Reference
ISO 10694. 1995. Soil Quality – Determination of organic and total carbon after dry combustion (elementary analysis). International Organization for Standardization. Geneva, Switzerland. 7 p. (available at www.iso.ch)
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563 Sampling and Analysis of Soil Part X
Soil Analysis Method 9 (SA09): Determination of Total Nitrogen Content
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Total Nitrogen Method sheet SA09A Reference methods ISO 13878 Method suitable for Organic Layer, Mineral Layer
I. Relevance in ICP Forests
Priority Level I Level II Organic Layer OL - - OF+OH, H-layers Mandatory Mandatory Mineral layer 0 – 10 cm Mandatory Mandatory 10 – 20 cm Mandatory Mandatory 20 – 40 cm Optional Optional 40 – 80 cm Optional Optional
II. Principle
The nitrogen content of a soil is determined by heating to a temperature of at least 900 °C in the presence of oxygen gas. Mineral and organic nitrogen compounds are oxidised and/or volatilised. The combustion products are oxides of nitrogen (NOx) and molecular nitrogen (N2). After transforming all nitrogen forms into N2, the content of total nitrogen is measured using thermal conductivity.
III. Apparatus
Laboratory glassware Analytical balance (accuracy 0.0001 or 0.00001 mg) Apparatus for determination of total nitrogen content (temperature at least 900 °C) Crucibles proper for the apparatus
IV. Reagents
Combustion gas - chemicals and catalysts proper to the apparatus Calibration substances
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V. Procedure
Laboratory sample Use fraction of air-dried soil (fraction < 2 mm) of known moisture content. If a soil mass of less than 2 g is required for nitrogen analysis, mill a representative subsample further, to pass a sieve of an aperture specified in the manufacturer’s manual to ensure sufficient test reproducibility. Calibration of the apparatus Calibrate the apparatus as described in the relevant manual using the calibration substances. Determination of total nitrogen content The amount of test sample for analysis depends on the expected total nitrogen content and on the apparatus used. Weigh out m1 g of the air-dried sample or subsample into a crucible. Carry out the analyses in accordance with the manufacturer’s manual for the apparatus.
Normally the primary results are given as milligrams nitrogen (X1) or a mass fraction of nitrogen (X2), expressed as a percentage, referred to the mass of air-dry soil used (m1).
VI. Calculation
Calculate the total content of nitrogen (wN), in milligrams per gram, on the basis of the air-dried soil according to the following equations: - For primary results given in milligrams of nitrogen:
X 1 wN = m1
- For primary results, given as percent mass fraction of nitrogen:
N = .10 Xw 2
where wN : total nitrogen content (g/kg) on basis of air-dried soil m1 : mass (g) of test portion X1 : primary result as milligrams N X2 : primary result as percentage N
VII. Report
Report total nitrogen (in g/kg) with 1 decimal place on the basis of oven-dried soil.
VIII. Reference
ISO 13878. 1998. Soil Quality – Determination of total nitrogen content by dry combustion ("elemental analysis"). International Organization for Standardization. Geneva, Switzerland. 5 p. (available at www.iso.ch)
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Total Nitrogen Modified Kjeldahl method Method sheet SA09B Reference methods ISO 11261 Method suitable for Organic Layer, Mineral Layer
I. Relevance in ICP Forests
Priority Level I Level II Organic Layer OL - - OF+OH, H-layers Mandatory Mandatory Mineral layer 0 – 10 cm Mandatory Mandatory 10 – 20 cm Mandatory Mandatory 20 – 40 cm Optional Optional 40 – 80 cm Optional Optional
II. Principle
The modified Kjeldahl method determines the total nitrogen content (including ammonium-N, nitrate-N, nitrite-N and organic N) of a soil. The method is based on a Kjeldahl digestion, but instead of selenium (Kjeldahl method) titanium dioxide is used as the catalyst.
III. Apparatus
Digestion flasks or tubes (50 ml) Digestion stand Distillation apparatus Burette (intervals of 0.01ml or smaller)
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IV. Reagents
Salicylic acid / Sulfuric acid: Dissolve 25g of salicylic acid in 1 litre of concentrated sulfuric acid (ρ = 1.84 g/cm3) Potassium sulfate catalyst mixture: Grind and thoroughly mix the following substances; 200 g of potassium sulfate 6 g of copper (II) sulfate pentahydrate 6 g of titanium dioxide with the crystal structure of anatase Sodium thiosulfate pentahydrate: Crush the crystals of Sodium thiosulfate pentahydrate until they form a powder that passes through a sieve with an aperture of 0.25mm Sodium hydroxide: c(NaOH) = 10 mol/l
Boric acid solution: ρ(H3BO3) = 20 g/l Mixed indicator: Dissolve 0.1 g of bromocresol green and 0.02 g of methyl red in 100 ml of ethanol Sulfuric acid: c (H+) = 0.01 mol/l
V. Procedure
Place a test portion from 0.2g (expected N-content 0.5%) to 1g (expected N-content of 0.1%) of the air-dried soil sample in the digestion flask. Add 4 ml of salicylic/sulfuric acid and swirl the flask until the acid is thoroughly mixed with the soil. Let the mixture stand for at least several hours (or overnight). Add 0.5 g of sodium thiosulfate trough a dry funnel with a long stem that reaches down into the bulb of the digestion flask. Heat the mixture cautiously on the digestion stand until frothing has ceased. Cool the flask and add 1.1g of the catalyst mixture, heat until the digestion mixture becomes clear. Boil the mixture gently for up to 5 h. (in most cases a boiling period of 2h. is sufficient) so that the sulfuric acid condenses about 1/3 of the way up to the neck of the flask. Make sure that the temperature of the solution does not exceed 400°C. Allow the flask to cool down after the digestion and add about 20ml of water slowly while shaking. Then swirl the flask to bring any insoluble material into suspension and transfer then the contents to the distillation apparatus. Rinse tree time with water to complete the transfer. Add 5 ml of boric acid to a 100 ml conical flask. Place the flask under the condenser of the distillation apparatus, make sure that the end of the condenser dips into the solution. Add 20 ml of sodium hydroxide to the funnel of the apparatus and run the alkali slowly into the distillation chamber. Distil about 40 ml of the condensate and rinse the end of the condenser. Add a few drops of indicator to the distillate and titrate with sulfuric acid to a violet endpoint or use a potentiometric titration with endpoint pH=5. version 5/2010 83
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Notes: Carry out a blank test in which the same procedure is performed without soil. A potentiometric titration is also possible (endpoint of titration should be pH = 5). If steam distillation is used, a distillation rate up to about 25ml/min is applicable. Stop the distillation when about 100ml of distillate have been collected.
VI. Calculation
The total nitrogen content is calculated by use of the following formula: + )()( ××− MHcVV 100 + w w = 01 N × 2OH N m 100 Where WN = The total nitrogen content (mg/g = g/kg) V1 = Volume of the sulfuric acid used in the titration of the sample (ml) V0 = Volume of the sulfuric acid used in the titration of the blank sample (ml) c(H+) = Concentration of H+ in the sulfuric acid (moles/litre) MN = The molar mass of nitrogen (= 14 g/mol) m = Mass of the air-dried soil sample (g) wH2O = Water content of the soil sample, based on oven-dried soil (% by mass)
VII. Report
Report total nitrogen in g/kg with 1 decimal place on the basis of oven-dried oil.
VIII. Reference
ISO 11261. 1995. Soil Quality – Determination of total nitrogen – Modified Kjeldahl method. International Organization for Standardization. Geneva, Switzerland. 4p. (available at www.iso.ch)
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569 Sampling and Analysis of Soil Part X
Soil Analysis Method 10 (SA10): Determination of Exchangeable Cations (Al, Ca, Fe, K, Mg, Mn, Na), Free H+ and Exchangeable Acidity
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Exchangeable acidity and exchangeable cations Method sheet SA10 Reference Methods ISO 11260 & ISO 14254 Method suitable for Organic Layer, Mineral Layer
I- Relevance in ICP Forests
Basic exchangeable cations (Ca, Mg, K, Na)
Priority Level I Level II Organic Layer OL - - OF+OH, H-layers Mandatory1 Mandatory1 Mineral layer 0 - 10 cm Mandatory Mandatory 10 – 20 cm Mandatory Mandatory 20 – 40 cm Optional Mandatory2 40 – 80 cm Optional Mandatory2 1 in calcareous soil, this parameter is optional 2 in case of re-assessment (if the parameter was already measured according to the reference method in a previous survey), the measurement is optional Acid exchangeable cations (Al, Fe, Mn), free H+ acidity and Exchangeable acidity
Priority Level I Level II Organic Layer OL - - OF+OH, H-layers Mandatory1 Mandatory1 Mineral layer 0 - 10 cm Mandatory1 Mandatory1 10 – 20 cm Mandatory1 Mandatory1 20 – 40 cm Optional Mandatory1,2 40 – 60 cm Optional Mandatory1,2 1 in calcareous soil, this parameter is optional 2 in case of re-assessment (if the parameter was already measured according to the reference method in a previous survey), the measurement is optional
II. Principle
The soil is first saturated with respect to barium by treating the soil one single time with a 0,1 mol/l barium chloride solution. 86 www.icp-forests.org/Manual.htm
571 Sampling and Analysis of Soil Part X
Concentrations of the exchangeable basic cations sodium, potassium, calcium and magnesium and the exchangeable acid cations iron, manganese, aluminium are determined in the 0.1 mol/l barium chloride extract of the soil using spectrometry. To determine exchangeable acidity, the 0.1 mol/l extract is titrated with a 0.05 mol/l NaOH solution up to pH = 7.8. Determination of the free H+ acidity is realised using a method in which sodium fluoride is added to the soil extract before the titration (Aluminium ions are complexed and only the free H+ acidity is detected during the titration process). Note: the reference method deviates from ISO 11260 & ISO 14254 in the sense that one single barium chloride extraction must be used instead of three extractions Alternatively the free H+ acidity can be determined by the “German calculation method” based on the pH of the barium chloride solution before and after extraction (König et al. 2005). The exchangeable acidity is subsequently calculated based on the sum of the acid cations and the free H+.
III. Apparatus
Centrifuge + centrifuge tubes Mechanical shaker Laboratory glassware Magnetic stirrer Funnel (diam. approx. 110 mm) Filter paper (diam. 150 mm) PE-bottles pH-meter Burette Atomic Absorption Spectrometer (AAS) / Flame Emission Spectrometer (FES) / Inductively Coupled Plasma Spectrometer (ICP)
IV. Reagents
Barium chloride (BaCl2) solution, conc. 0.1 mol/l Sodium hydroxide (NaOH) solution, conc. 0.05 mol/l Sodium fluoride (NaF) solution, conc. 1 mol/l pH buffer solutions Calibration substances
V. Procedure
Laboratory sample Use 2.5 g air-dried soil (particle size < 2 mm) of known moisture content.
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Leaching procedure Place the laboratory sample in a 50 ml centrifuge tube. Add 30 ml barium chloride solution and shake for 2 hours. Centrifuge at 3000 g for 10 min. Transfer the supernatant liquid through a filter into a PE-bottle. Retain the extract for analysis (Volume V). If the filtered extract solution is not enough for the measurement of all cations and pH the extract solution can be diluted (for example 1:5) with barium chloride solution. This has to be considered when calculating the concentrations in the extract. Alternatively it is allowed to use higher volumes of barium chloride solution, but the ratio soil to solution must always be the same (e.g. 5.0 g soil and 60 ml barium chloride solution)!
Note: According to ISO 11260 & ISO 14254 three BaCl2 extractions should be done and each time shaken for 1 hour in contrast to this analytical method (SA10).
Determination of exchangeable cations (Ca, Mg, K, Na, Al, Fe, Mn) Measure the exchangeable cations in the extract using one of the spectrometric determination methods.
Determination of free H+ Pipette 25 ml of the extract (Volume Vs). Add 1.25 ml of the sodium fluoride (1 mol/l) solution. Titrate with the sodium hydroxide (0.05 mol/l) solution to a pH value of 7.8. Titrate a blank in the same way.
Note: If 25 ml is not sufficient for the titration, new BaCl2 extract, in accordance to ISO 11260, should be obtained and used.
Determination of exchangeable acidity Pipette 25 ml of the extract into a container of sufficient capacity to also receive the electrodes of the pH-meter. Insert the electrodes and titrate with the sodium hydroxide (0.05 mol/l) solution until a pH value of 7.8 is reached and remains stable for 30 s. Repeat the procedure for a blank 0.1 mol/l BaCl2 solution extract.
Note: If 25 ml is not sufficient for the titration, new BaCl2 extract, in accordance to ISO 11260, should be obtained and used.
VI. Calculation
Determination of exchangeable cations (Ca, Mg, K, Na, Al, Fe, Mn) Calculation according to apparatus taking into account following equivalent mass in g/mol: Na+ = 22,99 Ca2+ = 20,04 Fe3+ = 18,62 Al3+ = 8,99 K+ = 39,10 Mg2+ = 12,16 Mn2+ = 27,47 H+ = 1,01 Calculation of the ion equivalents per g soil: ∗ Vc IE = ∗ 10 * EQ m EQ * 10 where IE ion equivalent in cmol/kg c element concentration in the extract in mg/l V volume of the added BaCl2-solution in ml (30 ml) 88 www.icp-forests.org/Manual.htm
573 Sampling and Analysis of Soil Part X
m mass of the soil sample in g (2,5 g) EQ equivalent mass of the element in g/mol
Determination of exchangeable acidity The total exchangeable acidity on basis of air-dried soil is given by:
− Ba NaOH .100..)( VcVV EA = s .mV where EA total exchangeable acidity (cmol/kg) of the soil on basis of air-dried soil VA volume NaOH (ml) used for the test sample VB volume NaOH (ml) used for the blank cNaOH concentration of NaOH (mol/l) VS volume (ml) pipetted for analysis m mass (g) of the laboratory sample V final volume (ml) of the extract
Determination of free H+ + For free H acidity use the same equation as for exchangeable acidity but use the volumes Va and Vb for the volume NaOH used in the titration for free acidity.
Alternative method for the determination of free H+ (“German” calculation method) Calculation of the Proton equivalent per gram soil:
− pH − p pH 0 ∗∗− ∗ + = −1 V 1000)1010( − )( VAlc kgcmolH *10)/( − m ∗ 88,0 ⎛ pH p ⎞ ⎜ +∗∗ 10 ⎟ AlMm ⎜1)( − 85,5 ⎟ ⎝ 10 ⎠ Or
− − pH p pH 0 + − V ∗∗− 1000)1010( )( ∗VAlc kgcmolH = 1 *10)/( − m ∗ 88,0 )( ∗∗ FAlMm Where F = the Ulrich/Prenzel factor. Values of the F factor for different pH values can be read from Table SA10-1. H+ = Free H+ in cmol/kg 10-1 = Conversion factor between units (μmol/g to cmol/kg) pHP = pH-value of the BaCl2 extract after the leaching procedure pH0 = pH-value of the pure BaCl2-extract V = Final Volume of the extract in ml (30 ml) m = Mass of the laboratory sample in g (2.5 g) c(Al) = Concentration of the Aluminium in the BaCl2 extract in mg/l M(Al) = Molar mass of Aluminium in g/mol (26,98 g/mol) F = Ulrich/Prenzel factor (cf. Table SA10-1) Note:As alternative method, the exchangeable acidity can be calculated as the sum of the exchangeable acid cations (Al, Fe, Mn, free H+).
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Table SA10-1: The Ulrich/Prenzel factor (F) for a range of pHp values (König and Fortman, 1996) pH F pH F pH F pH F pH F pH F 4,6 18,8 4,1 57,2 3,6 179 3,1 563 2,6 1774 4,59 19,2 4,09 58,5 3,59 1 83 3,09 576 2,59 1816 4,58 19,6 4,08 59,9 3,58 187 3,08 590 2,58 1858 4,57 20,1 4,07 61,3 3,57 192 3,07 604 2,57 1900 4,56 20,5 4,06 62,7 3,56 196 3,06 618 2,56 1943 4,55 21 4,05 64,1 3,55 201 3,05 632 2,55 1993 4,54 21,4 4,04 65,6 3,54 205 3,04 647 2,54 2035 4,53 21,9 4,03 67,1 3,53 210 3,03 662 2,53 2084 4,52 22,4 4,02 68,6 3,52 215 3,02 677 2,52 2134 4,51 22,9 4,01 70,2 3,51 220 3,01 693 2,51 2183 4,50 23,4 4 71,8 3,5 225 3 709 2,5 2233 4,49 23,9 3,99 73,5 3,49 230 2,99 721 2,49 2289 4,48 24,4 3,98 75,1 3,48 235 2,98 743 2,48 2341 4,47 25 3,97 76,9 3,47 241 2,97 757 2,47 2401 4,46 25,5 3,96 78,6 3,46 246 2,96 778 2,46 2451 4,45 26,1 3,95 80,4 3,45 252 2,95 792 2,45 2511 4,44 26,7 3,94 82,3 3,44 258 2,94 813 2,44 2571 4,43 27,3 3,93 84,2 3,43 264 2,93 827 2,43 2631 4,42 27,9 3,92 86,2 3,42 270 2,92 848 2,42 2691 4,41 28,5 3,91 88,1 3,41 276 2,91 870 2,41 2751 4,4 29,2 3,9 90,1 3,4 283 2,9 891 2,4 2821 4,39 29,8 3,89 92,2 3,39 289 2,89 912 2,39 2881 4,38 30,5 3,88 94,3 3,38 296 2,88 933 2,38 2961 4,37 31,2 3,87 96,5 3,37 303 2,87 954 2,37 3021 4,36 31,9 3,86 98,7 3,36 310 2,86 976 2,36 3091 4,35 32,6 3,85 101 3,35 317 2,85 997 2,35 3161 4,34 33,4 3,84 103 3,34 325 2,84 1024 2,34 3241 4,33 34,1 3,83 106 3,33 332 2,83 1046 2,33 3311 4,32 34,9 3,82 108 3,32 340 2,82 1067 2,32 3391 4,31 35,7 3,81 111 3,31 348 2,81 1095 2,31 3471 4 3 36,5 3,8 113 3,3 356 2,8 1117 2,30 3551 4,8 12,2 4,29 37,3 3,79 116 3,29 364 2,79 1145 2,29 3631 4,79 4,28 38,2 3,78 118 3,28 373 2,78 1173 2,28 3721 4,78 4,27 39 3,77 121 3,27 381 2,77 1202 2,27 3801 4,77 13 4,26 39,9 3,76 124 3,26 390 2,76 1230 2,26 3891 4,76 13,3 4,25 40,8 3,75 127 3,25 399 2,75 1258 2,25 3981 4,75 13,6 4,24 41,7 3,74 130 3,24 408 2,74 1286 2,24 4071 4,74 13,9 4,23 42,7 3,73 133 3,23 418 2,73 1315 2,23 4171 4,73 14,2 4,22 43,9 3,72 136 3,22 430 2,72 1350 2,22 4271 4,72 14,5 4,21 44,7 3,71 139 3,21 438 2,71 1378 2,21 4371
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4,71 14,8 4,20 45,1 3,70 142 3,20 448 2,70 1413 2,20 4471 4,7 15,1 4,19 46,7 3,69 146 3,19 458 2,69 1442 2,19 4571 4,69 15,5 4,18 47,3 3,68 149 3,18 469 2,68 1477 2,18 4681 4,68 15,8 4,17 48,9 3,67 152 3,17 480 2,67 1512 2,17 4791 4,67 16,1 4,16 50 3,66 156 3,16 491 2,66 1548 2,16 4901 4,66 16,5 4,15 51,1 3,65 159 3,15 502 2,65 1583 2,15 5001 4,65 16,8 4,14 52,3 3,64 163 3,14 514 2,64 1618 2,14 5131 4,64 17,2 4,13 53,5 3,63 167 3,13 526 2,63 1654 2,13 5251 4,63 17,6 4,12 54,7 3,62 170 3,12 538 2,62 1695 2,12 5371 4,62 18 4,11 56 3,61 175 3,11 551 2,61 1731 2,11 5501 4,61 18,4 4,10 57,2 3,60 179 3,10 563 2,60 1774 2,10 5621
VII. Report
+ Report (in cmol(+)/kg) total exchangeable acidity, exchangeable cations and free H with 2 decimal places on the basis of oven-dried soil.
VIII. References
ISO 11260. 1994. Soil Quality – Determination of effective cation exchange capacity and base saturation level using barium chloride solution. International Organization for Standardization. Geneva, Switzerland. 10 p. (available at www.iso.ch) ISO 14254. 1994. Soil Quality – Determination of exchangeable acidity in barium chloride extracts. International Organization for Standardization. Geneva, Switzerland. 5 p. (available at www.iso.ch) König and Fortmann 1996. Probenvorbereitungs-, Untersuchungs- und Element-bestimmungsmethoden des Umweltlabors der Niedersächsischen Forstlichen Versuchsanstalt und des Zentrallabors II des Forschungszentrums Waldökosysteme, Teil 4: Probenvorbereitungs- und Untersuchungsmethoden, Qualitätskontrolle und Datenverarbeitung; Berichte des Forschungszentrums Waldökosyst. B, Bd. 49, Untersuchungsmethode Boden AKEG1.1 Gutachterausschuss Forstliche Analytik: Handbuch Forstliche Analytik. König, N. and Bartners, H. Eds. 2005. Loseblatt-Sammlung der Analysemethoden im Forestbereich, 433 pg. (Method A3.2.1.3)
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Soil Analysis Method 11 (SA11): Aqua Regia Extractant Determinations P, Ca, K, Mg, Mn, Cu, Pb, Cd, Zn, Al, Fe, Cr, Ni, S, Hg, Na
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Aqua Regia extractant determinations P, Ca, K, Mg, Mn, Cu, Pb, Cd, Zn, Al, Fe, Cr, Ni, S, Hg, Na Method sheet SA11 Reference methods ISO 11466 Method suitable for Organic Layer, Mineral Layer
I. Relevance in ICP Forests
Aqua Regia extractant determinations (P, Ca, K, Mg, Mn)
Priority Level I Level II Organic Layer OL Optional Optional OF+OH, H-layers Mandatory Mandatory Mineral layer 0 - 10 cm Optional Optional 10 – 20 cm Optional Optional 20 – 40 cm Optional Optional 40 – 80 cm Optional Optional
Aqua Regia extractant determinations (Cu, Pb, Cd, Zn)
Priority Level I Level II Organic Layer OL Optional Optional OF+OH, H-layers Mandatory Mandatory Mineral layer 0 - 10 cm Mandatory Mandatory 10 – 20 cm - - 20 – 40 cm - - 40 – 80 cm - -
Aqua Regia extractant determinations (Al, Fe, Cr, Ni, S, Hg, Na)
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Priority Level I Level II Organic Layer OL Optional Optional OF+OH, H-layers Optional Optional Mineral layer 0 - 10 cm Optional Optional 10 – 20 cm - - 20 – 40 cm - - 40 – 80 cm - -
II. Principle
The dried sample is extracted with a hydrochloric/nitric acid mixture by standing for 16 h at room temperature, followed by boiling under reflux for 2 h. The digestion by the use of a microwave apparatus is not allowed as results are not comparable for matrices which give residues after digestion. The extract is then clarified and made up to volume with nitric acid. Elements are determined by spectrometry.
III. Apparatus
Analytical balance (accuracy 0.001 g) Desiccator (2 l) Reaction vessel (250 ml) Reflux condenser Absorption vessel, non return type, containing 15 ml of nitric acid (0.5 mol/l) (only necessary for determination of mercury) Roughened glass beads or antibumping granules Temperature-controlled heating apparatus Funnel (diam. approx. 110 mm) Volumetric flask (110 ml) Filter paper (diam. 150 mm, pore size approx. 8 μm) Atomic Absorption Spectrometer (AAS) / Flame Emission Spectrometer (FES) / Inductively Coupled Plasma Spectrometer (ICP) / Colorimeter
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IV. Reagents
Watesr (grade 2) Hydrochloric acid (HCl) concentration 12 mol/l, 1.19 g/ml
Nitric acid (HNO3) concentration 15.8 mol/l, 1.42 g/ml
Nitric acid (HNO3) concentration 0.5 mol/l
V. Procedure
Laboratory sample Weigh 3.000 g air-dried soil (particle size < 2 mm) of known moisture content in the 250 ml reaction vessel. Note: Because we are interested in the easily available elements, it is not allowed to mill the < 2mm sample. This deviates from the ISO standard.
Aqua regia extraction Moisten with about 0.5 ml to 1.0 ml of water and add, while mixing, 21 ml of hydrochloric acid followed by 7 ml of nitric acid (15.8 mol/l), drop by drop if necessary, to reduce foaming. Connect the condenser (and the absorption vessel) to the reaction vessel, and allow to stand for 16 h at room temperature to allow for slow oxidation of the organic matter in the soil. The amount of aqua regia is sufficient only for oxidation of about 0.5 g of organic carbon. If there is more than 0.5 g of organic carbon in the 3 g subsample, proceed as follows. Allow the first reaction with the aqua regia to subside. Then add an extra 1 ml of nitric acid (15.8 mol/l) only to every 0.1 g of organic carbon above 0.5 g. Do not add more than 10 ml of nitric acid at any time, and allow any reaction to subside before proceeding further. Raise the temperature of the reaction mixture slowly until reflux conditions are reached and maintain for 2 h, ensuring that the condensation zone is lower than 1/3 of the height of the condenser, then allow to cool. Allow the reaction vessel to stand so that most of any insoluble residue settles out of suspension. (Add the contents of the absorption vessel to the reaction vessel, via the condenser, rinsing both the absorption vessel and condenser with a further 10 ml of nitric acid (0.5 mol/l)). Decant the relatively sediment-free supernatant carefully onto a filter paper, collecting the filtrate in a 100 ml volumetric flask. Allow all the initial filtrate to pass through the filter paper, then wash the insoluble residue onto the filter paper with a minimum of nitric acid (0.5 mol/l). Collect this filtrate with the first. before proceeding further. The extract thus prepared is ready for the determination of trace elements, by an appropriate method.
Determination of elements (P, Ca, K, Mg, Mn, Cu, Pb, Cd, Zn, Al, Fe, Cr, Ni, S, Hg, Na) Measure the elements cations in the extract using one of the spectrometric determination methods. Note: ISO 11047 can be used as a guideline for the determination of Cd, Cr, Cu, Pb, Mn, Ni and Zn.
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VI. Calculation
Determination of elements (P, Ca, K, Mg, Mn, Cu, Pb, Cd, Zn, Al, Fe, Cr, Ni, S, Hg, Na) Calculation according to apparatus.
VII. Report
Report aqua regia extract determinations (mg/kg) with 1 decimal place on the basis of oven-dried soil. Note: Laboratories which have the possibility to determine the Cu content up to 2 decimal places and the Hg content up to 3 decimal places, are given the opportunity to report accordingly.
VIII. Reference
ISO 11466. 1995. Soil Quality – Extraction of trace elements soluble in aqua regia. International Organization for Standardization. Geneva, Switzerland. 6 p. (available at www.iso.ch) ISO 11047. 1998. Soil Quality – Determination of cadmium, chromium, cobalt, copper, lead, manganese nickel and zinc. Flame and electrothermal atomic absorption spectrometric methods. International Organization for Standardization. Geneva, Switzerland. 6 p. (available at www.iso.ch)
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Soil Analysis Method 12 (SA12): Determination of Total Elements Ca, Mg, Na, K, Al, Fe, Mn
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Total Elements: Ca, Mg, Na, K, Al, Fe, Mn Method 1 : Dissolution with hydrofluoric and perchloric acids Method sheet SA12A Reference methods ISO 14869 Method suitable for Organic Layer, Mineral Layer
I. Relevance in ICP Forests
Priority Level I Level II Organic Layer OL - - OF+OH, H-layers - - Mineral layer 0 – 10 cm - Optional 10 – 20 cm - Optional 20 – 40 cm - Optional 40 – 80 cm - Optional
II. Principle
This method specifies the complete dissolution, using hydrofluoric and perchloric acids, of the following elements in soils: Al, Ba, Cd, Ca, Cs, Cr, Co, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, Sr, V, Zn. This procedure may be appropriate for the subsequent determination of other elements provided their concentrations are high enough relative to the sensitivity of the measurement methods. The low acid concentration of the final solution allows the use of a large range of analytical devices and the volatilisation of silicon simplifies analytical procedures. The dried and ground sample is pre-treated to destroy organic matter, and then digested with a mixture of hydrofluoric and perchloric acids. After evaporation to near dryness, the residue is dissolved in dilute hydrochloric or nitric acid. Hydrofluoric acid decomposes silicates by the reaction of F with Si to form volatile SiF4. As it evaporates last, perchloric acid forms readily-soluble perchlorate salts. To minimise the danger of acid ejection due to violent oxidation of organic matter by perchloric acid, two alternative procedures have been adopted to destroy organic matter prior to digestion: dry ashing at 450 °C; pretreatment with nitric acid. 100 www.icp-forests.org/Manual.htm
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III. Apparatus
Mill Drying oven and desiccator Analytical balance (accuracy 0.0001 g) Crucible of fused silica or platinum (10 - 30 ml) Furnace (temperature 450 °C) Evaporating dishes made of polytetrafluoroethylene (PTFE) Hot plate (150 °C) Fume hood Volumetric flask of polypropylene (50 ml) Atomic Absorption Spectrometer (AAS) / Flame Emission Spectrometer (FES) / Inductively Coupled Plasma Spectrometer (ICP)
IV. Reagents
Water (grade 2) Hydrofluoric acid (HF), conc. 27.8 mol/l, = 1.16 g/ml
Perchloric acid (HClO4), conc. 11.6 mol/l, = 1.67 g/ml Hydrochloric acid (HCl), conc. 12.1 mol/l, = 1.19 g/ml Nitric acid (HNO3), conc. 15.2 mol/l, = 1.41 g/ml
V. Procedure
Attention ! Always use latex gloves while working with HF and keep the ointment against HF acid bites ready for eventual accidents ! Laboratory sample Use air-dried soil milled as fine as possible. Weigh precisely 0.250 g of the milled sample. Destruction organic matter
Dry ashing Transfer soil sample to a crucible. Place the crucible in the furnace and allow the temperature to reach 450 °C, progressively over 1 h. Maintain this temperature for 3 h. Allow the furnace to cool to room temperature and transfer the ash quantitatively to a PTFE evaporating dish with a minimum amount of water. Using a platinum crucible of about 30 ml avoids ash being transferred to a PTFE dish and allows digestion to be performed in the same container as dry ashing.
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successive additions of nitric acid may be necessary until the emission of nitrous vapours ceases to remove all the organic matter. In such cases, remove the dish from the hot plate and cool to room temperature before adding the next portion of nitric acid. After the last addition of nitric acid, remove the dish from the hot plate and cool to room temperature.
Total digestion Add 5 ml of hydrofluoric acid and 1.5 ml of perchloric acid to the pretreated test portion in the PTFE dish or the 30 ml platinum crucible. Heat this mixture on the hot plate until the dense fumes of perchloric acid and silicon tetrafluoride cease. Do not allow the mixture to evaporate to complete dryness. Remove the dish from the hot plate, allow to cool, add 1 ml of hydrochloric acid or 1 ml of nitric acid and approximately 5 ml of water to dissolve the residue. Warm the dish briefly on the hot plate to assist dissolution. Transfer this solution quantitatively to the 50 ml volumetric flask, fill to the mark and mix well. A solid phase remaining in the resultant solution indicates incomplete dissolution. It may be of no importance with respect to the elements of interest, especially when pure silica constitutes the solid phase, but in that case, the procedure shall be completed by one of the following stages. The procedure is stopped at this point and failure of total dissolution with a possible effect on the determination of total contents is noted in the test report. The procedure is adjusted to improve the dissolution. One or a combination of the three following treatments is carried out. The procedure is started again with a new test portion but a further dose of 5 ml of hydrofluoric acid and 1.5 ml of perchloric acid is added after evaporation of the first one to near dryness. The second dose is also evaporated as above and the procedure is carried on as described above. The procedure is started again with a new test portion but after the addition of hydrofluoric and perchloric acids the mixture is left overnight at room temperature before being heated as described above. The whole procedure is not changed but the mass of the test portion is reduced. If a solid phase remains in spite of these further treatments, then failure of total dissolution is mentioned in the test report.
Blank test Use the same procedure, without the sample, to perform at least one blank test within each batch of digestions.
Determination of total elements (Ca, Mg, K, Na, Al, Fe, Mn) Measure the total elements in the extract using one of the spectrometric determination methods.
VI. Calculation
Determination of total elements (Ca, Mg, K, Na, Al, Fe, Mn) Calculation according to apparatus.
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VII. Report
Report total elements (mg/kg) with one decimal place on the basis of oven-dried soil.
VIII. References
ISO 14869-1. 2001. Soil Quality – Dissolution for the determination of total element content - Part 1: Dissolution with hydrofluoric and perchloric acids. International Organization for Standardization. Geneva, Switzerland. 5 p. (available at www.iso.ch)
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Total Elements: Ca, Mg, Na, K, Al, Fe, Mn Method 2 : Total element analysis by fusion with lithium metaborate Method sheet SA12B Reference methods ISO 14869 Method suitable for Organic Layer, Mineral Layer
I. Relevance in ICP Forests
Priority Level I Level II Organic Layer OL - - OF+OH, H-layers - - Mineral layer 0 – 10 cm - Optional 10 – 20 cm - Optional 20 – 40 cm - Optional 40 – 80 cm - Optional
II. Principle
This method specifies the fusion using lithium metaborate.
III. Apparatus
Platinum crucibles Muffle furnace Magnetic stirring devices Analytical balance (accuracy 0.0001 g)
Filter paper prewashed (with a 10% HNO3 or HCl solution)
IV. Reagents
Lithium metaborate (LiBO2) on powder
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V. Procedure
Laboratory sample Use air-dried soil (milled < 0.4 mm). Weigh 0.4 g of the milled sample.
Destruction organic matter The sample is put to each platinum crucible and pre-ignited at 850 C for 30 min as to avoid damaging the platinum crucible when it would be mixed with lithium metaborate. The reason for this is that the soil organic matter can cause reduction of the platinum during the fusion.
Fusion After the crucibles are cooled (usually it takes one night) the pre-ignited soil is mixed thoroughly (by means of a pipette tip) with 2 g of lithium metaborate powder in a platinum crucible and fused for 15 min at 950°C in a preheated muffle furnace. The crucible and flux that is formed are allowed to cool for one night. The reason for this is that if we try to remove them from the furnace immediately after heating by means of something metallic, there will be a reaction between the platinum and the metal. The crucibles are immersed in a 100 ml beaker and covered with 70-80 ml of 4% nitric acid. A magnetic stirring bar is then placed inside the crucible and stirring can begin immediately. The flux is dissolved in 3 to 4 hr (occasionally it might take a little more) and the solution is made up to 100 ml, filtered through a prewashed (with a 10% HNO3 or HCl solution) paper filter of 0.45 mm and stored for analysis.
Blank test Use the same procedure, without the sample, to perform at least one blank test within each batch of digestions.
Determination of total elements (Ca, Mg, K, Na, Al, Fe, Mn) Measure the total elements in the extract using one of the spectrometric determination methods.
VI. Calculation
Determination of total elements (Ca, Mg, K, Na, Al, Fe, Mn) Calculation according to apparatus.
VII. Report
Report total elements (mg/kg) with one decimal place on the basis of oven-dried soil.
VIII. References
Michopoulos, P. 1995. Studies on manganese cycling in forest soils. PhD Thesis. University of Aberdeen. Potts, P.J. 1987. A handbook of Silicate Rock Analysis. Blackie, New York.
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Soil Analysis Method 13 (SA13). Determination of Acid Oxalate Extractable Fe and Al
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Acid Oxalate Extractable Fe and Al Method sheet SA13 Reference methods ISRIC, 2002 Method suitable for Organic Layer, Mineral Layer
I. Relevance in ICP Forests
Priority Level I Level II Organic Layer OL - - OF+OH, H-layers Optional Optional Mineral layer 0 – 10 cm Optional Mandatory 10 – 20 cm Optional Mandatory 20 – 40 cm Optional Mandatory1 40 – 80 cm Optional Mandatory1 1 In case of re-assessment (if the parameter was already measured according to the reference method in a previous survey), the measurement is optional
II. Principle
The sample is shaken with a complexing acid ammonium oxalate solution dissolving the "active" or "short range order" ( "amorphous") compounds of Fe, Al (and Si) and a (variable) amount of organically complexed Fe and Al which are determined in the extract by AAS or ICP-AES. The ammonium oxalate buffer extraction is sensitive to light, especially UV light. The exclusion of light during the extraction reduces the dissolution effect of crystalline oxides. Superfloc is added as a flocculent to the solution to remove the fine, suspended, solid particles, often made up of iron minerals (ferrihydrite). While conducting this analysis for classification purposes, no Superfloc should be added.
III. Apparatus
Reciprocating shaking machine Centrifuge Atomic absorption spectrophotometer (with nitrous oxide/acetylene flame) or Inductive Coupled Plasma Atomic Emission Spectrofotometer (ICP-AES) Polythene shaking bottles, wide mouth, 100 and/or 250 ml
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IV. Reagents
In this procedure distilled water is used since deionised water may contain Si. Acid ammonium oxalate solution, 0.2 M in oxalate, pH 3:
Dissolve 81 g (COONH4)2.H2O and 54 g (COOH)2.2H2O in 4.5 l water and make to 5 l. Prepare 1 l of two separate 0.2 M solutions of NH4-oxalate (28 g/l) and oxalic acid (25 g/l) and add some of either solution to the mixture until the pH is 3. Potassium suppressant solution, 10,000 mg/l K: Dissolve 19 g KCl in 800 ml water and make up to 1 l. "Superfloc" solution, 0.2%: Dissolve 0.1 g superfloc flocculent in 50 ml water. Stir overnight in the dark. (Note: store in the dark. This solution can be kept for about a week). Superfloc is a flocculent used in waste water treatment. E.g. Cyanamid Superfloc N-100 and Floerger Kemflock FA 20H Diluent solution (5x): Make 2.38 g KCl and 25 ml conc. HCl to 1 l with water. Diluent solution (20x): Make 2.01 g KCl, 158 ml acid ammonium oxalate solution and 21 ml conc. HCl to 1l with water. Standard solutions Fe and Al, 250 mg/l: Dilute standard analytical concentrate ampoules (1g/l) according to instruction to make 1000 mg/l solutions. Dilute each to 250 mg/l by pipetting 50 ml into a 200 ml volumetric flask and making up to volume with water. Mixed standard series of Fe and Al: 1. To each of five 250 ml volumetric flasks add 50 ml of the acid oxalate reagent, 25 ml of the KCl suppressant solution and 5 ml conc. HCl (or 10 ml 6 M HCl) 2. Of each 250 mg/l standard solution pipette 0-5-10-25-50 ml into the 250 ml volumetric flask (same volumes into same flasks respectively) and make to volume with water. The standard series are then: Fe, Al, 0-5-10-25-50 mg/l.
V. Procedure
1. Weigh 1 g of fine earth (accuracy 0.01 g) into a 100 ml shaking bottle. Include two blanks and a control sample. 2. Add 50.0 ml oxalate reagent and close the bottle. (Note: for soils with relatively high contents of oxalate-extractable material (Al, Fe>2%) use 100.0 ml oxalate reagent and a 250 ml shaking bottle). 3. Shake for four hours in the dark. 4. Transfer about 35 ml to a 50 ml centrifuge tube
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6. Prepare 5x and 20x dilutions: 5x dilution Pipette 1 ml of the clear supernatant and 4 ml of the diluent solution (5x) into a test tube and homogenise. 20x dilution Pipette 1 ml of the clear supernatant solution and 19 ml ( by varispencer or burette) of the diluent solution (20x) into a wide test tube and homogenise 7. Measure Fe by AAS at 248.3 nm using an air/acetylene flame and measure Al by AAS at 309.3 nm using a nitrous oxide/acetylene flame. Or measure by ICP-AES. Refer to the manufacturer’s manual for operation. Note: In case of over ranged (diluted) extracts, dilute these once more 1+1 with the zero standard solution. Therefore, of the latter an extra 250 or 500 ml should be prepared. Change the calculation accordingly.
VI. Calculation
Calculate the oxalate extractable Fe and Al, on the basis of the air-dried soil according to the following equation: − )( × dfba kgmgAlFe )/(, = mlox ×× 1000. s where a = mg/l Fe, Al in diluted sample extract b = diato in diluted blank df = dilution factor ml ox. = ml of oxalate reagent used (50 or 100) s = air dry sample weight in milligram 1000 = conversion factor to mg/kg basis
VII. Report
Report oxalate extractable Fe and Al (mg/kg) with one decimal place on the basis of oven-dried soil.
VIII. Reference
ISRIC, FAO. 2002. Procedures for soil analysis. Sixth ed. ISRIC Technical Paper 9. L.P. Van Reeuwijk (ed). Wageningen, The Netherlands. USDA National Resources Conservation Service, 2004. Survey Laboratory Methods Manual. Soil Investigations report N°.42, Version 4.0, pages 312-317.
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Soil Analysis Method 14 (SA14): Determination of the Soil Water Retention Characteristic
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Soil water retention characteristic (pF analysis) (SWRC) Method sheet SA14 Reference method ISO 11274 Method suitable for Mineral and organic soil horizons, undisturbed samples
I. Relevance in ICP Forests
PRIORITY LEVEL I AND LEVEL II LEVEL II CORE Organic layer OL - - OF-OH, H - layers Optional Mandatory if > 5 cm Mineral layer 0 – 20 cm Optional Mandatory 20 – 40 cm Optional Mandatory 40 – 80 cm Optional Mandatory > 80 cm Optional Optional Extra (specific) layer Optional Optional
The volumetric water content at matric heads 0, -1, -5, -33 and -1500 kPa plus the dry soil bulk density are mandatory to determine on Level II core plots. Extra observations of the SWRC at pressures -10, -100 and -250 kPa are optional but they greatly improve fitting the soil water retention characteristic (SWRC). Some matric heads immediately provide information on SWRC parameters: at 0 kPa the maximum water holding capacity (WHC) of the saturated soil sample is determined; depending on definitions and soil texture field capacity (FC) may be inferred from -10 till -100 kPa; permanent wilting point (PWP) is attained at a matric pressure of –1500 kPa and dry bulk density (BD) (lowest pressure at about 10-6 kPa) derived in the oven at 105°C.
II. Principle
This method sheet describes the determination of the soil water retention in the laboratory, extending from saturated soil (no pressure or suction; 0 kPa) to oven-dry soil (about -106 kPa) based on measurements of the drying or desorption curve. All methods described by ISO 11274 are allowed, except method B, using a porous plate and burette apparatus for matric pressures from 0 to -20 kPa. In order to determine the SWRC, the volumetric water content (θ in volume fraction, m3 m-3) is determined at predefined matric potentials (ψ, in kPa). The volumetric soil water content at matric pressure 0 kPa is approximated by the total porosity of the soil. The ISO 11274:1998 allows 4 methods to determine matric pressures within specific ranges:
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method using sand, kaolin or ceramic suction tables for determination of matric pressures from 0 kPa to - 50 kPa; method using a porous plate and burette apparatus for determination of matric pressures from 0 kPa to - 20 kPa; (single sample) method using a pressurized gas and a pressure plate extractor for determination of matric pressures from - 5 kPa to - 1500 kPa; method using a pressurized gas and pressure membrane cells for determination of matric pressures from - 33 kPa to - 1500 kPa. Since method B allows only processing a single sample at the time, use of this method is not recommended. Laboratories are free to apply methods A, C and D according to the ISO 11274 standard. Guidelines for choosing the most appropriate method for specific soil types are given in ISO 11274, chapter 3. Before applying methods A, C or D, general recommendations for sample preparation are: For measurements at pressures from 0 to -50 kPa, use a nylon mesh to retain the soil sample in the sleeve and secure it with an elastic band or tape; Ensure maximum contact between the soil core, mesh and the porous contact medium of the suction tables, plates or membranes; remove any small projecting stones if necessary; Avoid smearing the surface of (clayey) soils, especially when water saturated; Inspect the sample for bioturbation (worms, isopods) or germination of seeds during analysis; the use of a biocide is discouraged; Report the temperature at which the water-retention measurements are made; Ideally, measurements use field-moist samples [i.e. do not dry the undisturbed samples first (hysteresis effect)]. Prior to analysis, samples are saturated with water. Respect wetting times before starting measurements to obtain a saturated sample. General guidelines for wetting times according to ISO 11274 are: - sand 1 to 5 days - loam 5 to 10 days - clay 5 to 14 days or longer - peat 5 to 20 days.
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Table I.14.1: Overview of matric heads to assess for the determination of the SWRC. Matric potential ψ Recommended instrument/Method Estimator M/O
cm H2O pF kPa 1 0.0 0 Pycnometer ≈θsat=WHC= Total porosity M 10 1.0 -1 Sand suction table (method A) M 51 1.7 -5 M 102 2.0 -10 FC sand O 337 2.5 -33 Kaolin suction table (method A) FC siltloam M 1022 3.0 -100 Pressure plate extractor (method C) or FC clay O Pressure membrane cells (method D) 2555 3.4 -250 O 15330 4.2 -1500 PWP M 107 7.0 -106 Oven Dry BD M
Where: 1) the pF is the logarithm of the absolute value of the matric potential expressed by the graduation of the water column (cm). 2) 1 kPa = 10.22 cm H2O or 1 cm H2O column = 0.097885 kPa 3) 100 kPa = 1 bar
III. Apparatus
Method A: Determination of the soil water characteristic using sand, kaolin and ceramic suction tables Suction table (watertight, rigid container with outlet in base and close fitting cover) Drainage system for suction table, enabling to maintain suction at specific matric pressures Sand, silt or kaolin packing material, appropriate for use in suction tables (homogenous, sieved, graded and washed, free of organic material or salts). Material should achieve the required air entry values (see ISO 11274 for details) Drying oven capable of maintaining temperature of 105 ± 2 °C Balance (accuracy 0.1% of measured value)
Method C: Determination of soil water characteristic by pressure plate extractor Pressure plate extractor with porous ceramic plate Sample retaining rings/soil cores with discs and/or lids Air compressor (1700-2000 kPa), nitrogen cylinder or other pressurized gas) Pressure regulator and test gauge Drying oven capable of maintaining temperature of 105 ± 2 °C Balance (accuracy 0.1% of measured value)
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Follow the manufacturer’s instruction to assemble and operate the apparatus.
Method D: Determination of soil water characteristic using pressure membrane cells Pressure cells with porous baseplates Cellulose acetate membrane Pressure regulator Air compressor (1700-2000 kPa, nitrogen cylinder or other pressurized gas) Drying oven capable of maintaining temperature of 105 ± 2 °C Balance (accuracy 0.1% of measured value) Follow the manufacturer’s instruction to assemble and operate the apparatus.
IV. Procedure
Method A: Determination of the soil water characteristic using sand, kaolin and ceramic suction tables Weigh the cores and then place them on a suction table at the desired matric pressure with table cover closed. The reference 0 cm height for setting the suction level is the middle of the core; Leave the cores for 7 days (minimum equilibration time). Equilibrium is reached if daily change in mass of the core is less than 0,02 %; If equilibrium is reached, weigh the cores, if not, replace cores firmly onto the suction table and wait until equilibrium is reached.
Method C: Determination of soil water characteristic by pressure plate extractor Take small subsamples from the undisturbed sample: soil cores of approximately 5 cm diameter and between 5 mm and 10 mm in height; smaller samples for lower pressures are used in order to avoid long equilibration times; It is acceptable to use disturbed samples at pressures lower than - 100 kPa, providing that the disturbance consists only in breaking off small pieces of soil and not in compressing or remoulding the soil. Use at least three replicate samples of each sample and place them on a presaturated plate; Wet the samples by immersing the plate and the samples until a thin film of water can be seen on the surface of the samples; Create a saturated atmosphere in the extractor; Apply the desired gas pressure and keep to a constant level, check for leaks; Record on a daily basis the evacuated water from the samples, when no change are observed (volume in a burette remains static) the samples have come to an equilibrium; At equilibrium status, soil samples are weighed, oven-dried and reweighed to determine the water content at the predetermined pressures
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Method D: Determination of soil water characteristic using pressure membrane cells Soil subsamples are placed on a porous cellulose acetate membrane Equilibrium status is attained when water outflow from the pressure cell ceases and soil water content is determined by weighing, oven-drying and reweighing the sample. Gas pressure methods are only suited to determine matric pressures below - 33 kPa
V. Calculation
V.1. Volumetric water content ISO 11274 describes two procedures: Procedure for soils containing less than 20 % coarse material (diameter greater than 2 mm) Procedure for stony soils; conversion of results to a fine earth basis
1. For soils with less than 20% coarse material:
Calculate the water content mass ratio at matric pressure ψi using the formula:
WCψi = (Mψi – Mdry) / Mdry where WCψi is the water content mass ratio at a matric pressure ψi, in grams; Mψi is the mass of the soil sample at matric pressure ψi, in grams; Mdry is the mass of the oven-dried soil sample, in grams.
Calculate the volumetric water content at matric pressure ψi using the formula:
-3 θψi = [(Mψi – Mdry) / (V x ρw) ] x 10 alternatively
θψi = WCψi x (ρb / ρw) where 3 -3 θψi is the water content volume fraction at matric pressure ψi, expressed in m m (volume of water per volume of soil); Mψi is the mass of the soil sample at matric pressure ψi, in grams; Mdry is the mass of oven dried soil sample, in grams; V is the volume of the soil sample in m³ - ρw is the density of water, in kg m ³ - ρb is the bulk density of oven dried soil at 105°C, in kg m ³.
2. For soils with more than 20% coarse material, data needs conversion to a fine earth basis as follows: The volumetric water content of the fine earth (θf) equals: θf = θt / (1- θs) where: θf water content of the fine earth, expressed as a volume fraction (m3 m-3); θs volume of non-porous stones, expressed as a fraction of total core volume (m3 m-3);
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(m3 m-3); For porous stones, a different correction should be applied as described in ISO 11274. If volumetric water content is reported on fine earth basis, this should be clearly reported along with the volume of non-porous stones in the sample.
V.2. Calculation of the total porosity
A value for porosity can be calculated from the bulk density ρbulk and particle density ρparticle:
Often the particle density or true density of soil is approximated by 2650 kg.m-³ (mineral density of quartz). But the direct measurement of the particle density is strongly recommended to be done by the means of a pycnometer.
V.3. Determination of dry bulk density Determination of dry bulk density is done according to method SA04. The dry bulk density (BD) is recorded in kg m-3 with no decimal places. In the case of stony or gravely soils the bulk density of the fine earth fraction (< 2 mm) should be reported. Furthermore, the bulk density of the coarse fragments should be known, but this may be approximated as 2650 kg.m-3.
VI. Report
Report for each undisturbed soil sample, the raw volumetric soil water content (θ = VWC in m3 m-3) with four decimal places using the xx20xx.SWA data form. Report the dry bulk density (BD) in kg m-3 without decimal places using the xx20xx.SWC file. Together with the laboratory results, following field data should be reported: plot ID, sampling data, pit ID, code depth layer, horizon number, sample ring depth (upper and lower side of the ring) in cm below the top of the mineral soil.
VII. References
ISO 11274:1998(E). Soil Quality – Determination of the water-retention characteristic – Laboratory methods. International Organization for Standardization. Geneva, Switzerland. 20 p. (available at www.iso.ch)
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Annex 2: Guidelines for Forest Soil Description
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Parameter Report in file M/O 1 GENERAL SITE INFORMATION 1.1. Observation plot number *.PLS, *.PRF, M *.PFH, *.SOM,*.LQA 1.2. Profile ID *.PRF,*.PFH M 1.3. Date of profile description *.PRF M 1.4. Profile latitude-/ longitude coordinates *.PRF M 1.5. Elevation *.PRF O
2 SOIL FORMING FACTORS 2.1. Climate and weather conditions 2.1.1. Present weather conditions 2.1.2. Former weather conditions 2.2. Soil climate 2.2.1. Cryic horizon 2.2.2. Soil climate classification 2.3. Topography 2.3.1. Slope position 2.3.2. Slope form 2.3.3. Slope gradient 2.3.4. Slope length 2.3.5. Slope orientation 2.4. Land use *.PRF M 2.5. Human influence 2.6. Vegetation 2.6.1. Forest type 2.6.2. Tree species composition 2.7. Parent material *.PRF M 2.8. Natural Drainage Classes 2.9. Water availability *.PLS M 2.10. Period of water saturation 2.11. External drainage 2.12. Flooding 2.12.1. Frequency 2.12.2. Duration (days/year) 2.12.3. Depth (of standing water) 2.13. Groundwater table 2.13.1. Mean highest and mean lowest groundwater depth *.PRF O 2.13.2. Type of water table *.PRF O
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2.14. Rock outcrops 2.14.1. Surface cover 2.14.2. Distance between rock outcrops 2.15. Coarse surface fragments 2.15.1. Surface cover 2.15.2. Size classes 2.16. Erosion & sedimentation 2.16.1. Type of erosion/sedimentation 2.16.2. Area affected 2.16.3. Degree 2.16.4. Activity 2.17. Surface sealing (FAO, 2006) 2.17.1. Thickness 2.17.2. Consistence when dry 2.18. Surface cracks (FAO, 2006) 2.18.1. Size (Width) 2.18.2. Distance between cracks 2.19. Salt 2.19.1. Cover 2.19.2. Thickness 2.20. Profile depth *.PRF M
3 SOIL HORIZON DESCRIPTION 3.1. Horizon boundary 3.1.1. Horizon number *.PFH M 3.1.2. Depth of horizon limits *.PFH M 3.1.3. Distinctness *.PFH O 3.1.4. Topography *.PFH O 3.2. Photographic recordings 3.3. Soil colour *.PFH M 3.4. Mottling 3.4.1. Colour 3.4.2. Abundance 3.4.3. Size 3.4.4. Contrast 3.4.5. Boundary 3.5. Redoximorphic properties 3.5.1. Reducing conditions 3.5.2. Reductimorphic and oximorphic colours
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3.6. Texture of the fine-earth fraction *.PFH M 3.7. Rock fragments 3.7.1. Abundance *.PFH M 3.7.2. Size of rock fragments and artefacts 3.7.3. Dominant shape of rock fragments 3.7.4. State of weathering of rock fragments 3.7.5. Nature (type) of rock fragments 3.8. Andic material 3.9. Soil structure 3.9.1. Type *.PFH M 3.9.2. Size 3.9.3. Grade 3.10. Consistence 3.10.1. Consistence when dry 3.10.2. Consistence when moist 3.10.3. Consistence when wet 3.11. Cutanic features 3.11.1. Type 3.11.2. Abundance 3.11.3. Contrast 3.11.4. Location 3.12. Porosity *.PFH O 3.13. Cementation and compaction 3.13.1. Nature (type) 3.13.2. Continuity 3.13.3. Structure 3.13.4. Degree 3.14. Nodules and other mineral concentrations 3.14.1. Kind 3.14.2. Type 3.14.3. Abundance (by volume) 3.14.4. Size 3.14.5. Shape 3.14.6. Hardness 3.14.7. Colour 3.15. Roots 3.15.1. Abundance *.PFH M* 3.15.2. Distribution
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3.16. Other biological features 3.16.1. Kind 3.16.2. Abundance 3.16.3. Continuity 3.17. Carbonates 3.17.1. Presence of carbonates 3.17.2. Type of secondary carbonates 3.18. Gypsum 3.18.1. Abundance of gypsum 3.18.2. Abundance of secondary gypsum 3.19. Readily soluble salts 3.20. Man-made materials 3.21. Human-transported material 3.22. Soil horizon designation *.PFH M
M: Mandatory to report O: Optional to report M*: Mandatory on plots with continuous soil moisture measurements
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0. Introduction
These guidelines are intended to help you to make the necessary field recordings and to collect other additional information enabling proper description of a forest soil profile and subsequent classification according to the World Reference Base for Soil Resources (IUSS Working Group WRB. 2007a, 2007b) as asked by the Manual Part X on Sampling and Analysis of Soil. These guidelines elaborate on variables which are not described elsewhere in this ICP Forests Manual. On the other hand, information collected in the other surveys can be very relevant to understand and interpret the soil profile correctly. In that case, reference is made to the concerning Parts of this Manual. These guidelines are largely based on the FAO (2006) Guidelines for soil description (4th edition) but do deviate for a number of parameters: 1. Concerning the horizon designation of the organic layer (master symbol ‘O’), the ICP Forests Manual continues to use the symbols OL, OF and OH, which is a tradition in the description of European forest soils whereas the FAO (2006) adopted recently the subordinate symbols i, e and a from the American soil classification system. 2. By consequence, there is not need to change the subordinate symbol ‘a’ standing for ‘evidence of cryoturbation’ as in FAO (1989) into the @ symbol as in FAO (2006).
1. General site information
1.1 Observation plot number (to be reported in *.PLS, *.PRF, *.PFH, *.SOM and *.LQA file) The observation plot number is the unique number given to each plot. It is reported with 4 digits. Example: Observation plot number [1012]
1.2 Profile ID (to be reported in *.PRF and *.PFH file) The soil profile identification number/code. It is reported with 4 characters. Example: Profile number [0149]
1.3 Date of profile description (to be reported in *.PRF file) The date of description in forms how old the data are and in what season they are recorded. The date of description is given as DDMMYY (6 digits). Example: 160504 (16 May 2004)
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1.4 Profile latitude-/ longitude coordinates (to be reported in *.PRF file) The coordinates of the centre of the observation plot is mandatory information. In addition it is also recommended to record the latitude and longitude coordinates of the soil profile pit as accurately as possible (in degrees and sexagesimal minutes and seconds). The point observation of the soil profile is the central point of the described soil profile wall. If possible, by preference a Global Positioning System (GPS) is used. If recording of the soil profile coordinates is impossible, then the distance (in metres and centimetres) and direction (in degrees) from the experimental plot centre should be measured and recalculated in coordinates. The location of the profile pit is reported as: Latitude geographic coordinates (+/- degrees, minutes, seconds) [WGS84] Longitude geographic coordinates (+/- degrees, minutes, seconds) [WGS84] Example: Latitude: 51° 23´ 31´´ N; is reported as +512331 Longitude: 11° 52´ 40´´ E; is reported as +115240
1.5 Elevation (to be reported in *.PRF file) The elevation or altitude (m above sea level) of the site should be obtained as accurately as possible.
2. Soil forming factors
Although the description of the soil forming factors are important for the correct interpretation of the soil profile, the soil module of the database does not ask to report most of these parameters, except for land use, parent material, water availability, mean highest and mean lowest groundwater level, profile depth (root, rock, obstacle depths). On the other hand, FSCC strongly recommends to record and store all soil forming variables at national level. The information may be derived from a combination of field measurements/observations, climatic records, topographical, geological and geomorphological maps and documents, and partly from the other surveys already conducted on the observation plots.
2.1 Climate and weather conditions
For the collection of meteorological data, see Manual IX on Meteorological Measurements.
2.1.1 Present weather conditions The weather condition at the time of the profile description is recorded, using following classes (after BBC weather)
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5 heavy rain 6 thunder storm 7 sleet 1) 8 hail 2) 9 snow
1) Sleet refers to snow that has partially melted when it touches the ground, due to surrounding air that is sufficiently warm to partially melt it while falling, but not warm enough to fully melt droplets into rain. Thus it refers to partially melted droplets, a mixture of snow and rain. It does not tend to form a layer on the ground, unless the ground has a temperature that is below freezing, when it can form a dangerous layer of invisible ice on surfaces known as 'black ice'. This similarly occurs when rain freezes upon contact with the ground (freezing rain) (http://en.wikipedia.org/).
2) Hail is a type of graupel, a form of precipitation, composed of spears or irregular lumps of ice. It occurs when supercooled water droplets (remaining in a liquid state despite being below the freezing point, 0 °C) in a storm cloud aggregates around some solid object, such as a dust particle or an already-forming hailstone. The water then freezes around the object. Depending on the wind patterns within the cloud, the hailstone may continue to circulate for some time, increasing in size. Eventually, the hailstone falls to the ground, when the updraft is no longer strong enough to support its weight (http://en.wikipedia.org/).
2.1.2 Former weather conditions (AG-Boden, 2004) This refers to the weather conditions prior to the time of the profile description.
Code Description 1 no rain during the last month 2 no rain during the last week 3 no rain during the last 24 hours 4 light rain during the last 24 hours 5 heavy rain or thunder during the last 24 hours 6 extremely rainy or snow melting
2.2 Soil climate
2.2.1 Cryic horizon Providing information on the soil climate is optional, except for those soils that may have a cryic horizon1 . A cryic horizon has following definition with respect to soil temperature: A cryic horizon must have a soil temperature at or below 0°C for two or more years in succession.
2.2.2 Soil climate classification (FAO, 2006) The soil climate classification can be indicated, if applicable. The soil moisture and temperature regimes according to the USDA Keys to Soil Taxonomy (Soil Survey Staff, 2003) may be used. Where such information is not available or cannot be derived from representative climatic data with confidence, it is better to leave the space blank. Other agro-climatic variables worth mentioning would be a local climate class, the agro-climatic zone and length of growing period.
1 Note that the temperature requirement for a cryic diagnostic horizon is different than for a cryic soil temperature regime. Whereas the temperature for the cryic soil temperature regime is measured at 50 cm depth, the cryic horizon may be present in all depths within the upper 100 cm to qualify for Cryosols, or within the upper 200 cm for other reference soil groups. version 5/2010 127
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Soil Temperature Regime Soil Moisture Regime Code Description Code Description Cod Description Code Descriptio e n PG Pergelic AQ Aquic PQ Peraquic CR Cryic AR Aridic FR Frigid IF Isofrigid TO Torric ME Mesic IM Isomesic UD Udic PU Perudic TH Thermic IT Isothermic US Ustic HT Hyperthermic IH Isohyperthermic XE Xeric
2.3 Topography
2.3.1 Slope position (after FAO, 2006) The position of the soil profile with respect to the slope is very important. Not only will the slope position have an influence on the external and internal drainage, but also the runoff and the subsurface flow are affected. A separate terminology is used for flat or almost flat (slopes of <10%) and undulating to mountainous terrains (slopes >10%) (Figure 1):
Position in flat or almost flat terrain Position in undulating to mountainous terrain Code Description Code Description 1 Higher part (rise) 5 Crest (summit) 2 Intermediate part 6 Upper slope (shoulder) 3 Lower part (and dip) 7 Middle slope 4 Bottom (drainage line) 8 Lower slope (foot slope) 9 Toe slope 10 Bottom (flat)
5 6 5 6
7 7 Channel
8 8 9 10
Alluvium
Figure 1: Slope positions in undulating and mountainous terrain (After Ruhe, 1975; Schoeneberger et al., 2002; FAO, 2006)
2.3.2 Slope form (after Schoeneberger et al., 2002; FAO, 2006) The slope form is described in two directions: up and down slope, which is perpendicular to the contour, and across slope, which is along the horizontal contour. The slope form classes defined are provided in Figure 2:
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Code Description 1 SS Straight, straight 2 SV Straight, convex 3 SC Straight, concave SS SV SC 4 VS Convex, straight 5 VV Convex, convex 6 VC Convex, concave 7 CS Concave, straight VS VV VC 8 CV Concave, convex 9 CC Concave, concave 10 Terraced 11 Complex (irregular) CS CV CC surface flow pathway F Figure 2: Slope forms and surface drainage pathways (after Schoeneberger et al., 2002)
2.3.3 Slope gradient (Modified from FAO, 2006) The slope gradient in the immediate surrounding of the soil profile should be measured using a clinometer, an abney level or a similar instrument. If measurements in the field are not possible, then the gradient can be calculated from the contour lines on detailed topographical maps. In practice, measuring slopes in forest can be problematic especially when the slope gradient is very gentle because then a longer distance is necessary to make an accurate measurement. If so, it is advised to base very gentle gradients (<2%) on topographical map readings. If the slope gradient is measured in degrees, then the gradient is calculated into percent, knowing that 45° equals 100%. Values above 100% are possible (often such steeps slopes are indeed left for forests).
Code Description Class limits 1 Flat 0 – 0.2 % 2 Level 0.2 – 0.5 % 3 Nearly level 0.5 – 1.0 % 4 Very gently sloping 1 - 2 % 5 Gently sloping 2 - 5 % 6 Sloping 5 - 10 % 7 Strongly sloping 10 - 15 % 8 Moderately steep 15 - 30 % 9 Steep 30 - 60 % 10 Very steep 60 - 100 % 11 Extremely steep >100 %
2.3.4 Slope length (FAO, 2006) In addition to the above attributes of slope, the slope length along the slope (particularly above the site) is recorded in meters.
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2.3.5 Slope orientation The slope orientation (azimuth) of the plot is mandatory to report in the general plot file at the time of the installation of the monitoring plot (XXGENER.PLT file) according to classes. See Part II of this Manual.
2.4 Land use
(to be reported in *.PRF file) Land use applies to the current use of the land. Land use greatly influences the direction and rate of soil formation; its recording greatly enhances the interpretative value of the soil data. The land- use should be described according to following list:
Code Description 50 Natural forest and woodland (mostly natural regeneration) 51 Natural forest and woodland without felling 52 Natural forest and woodland with selective felling 53 Natural forest and woodland with clear felling
60 Plantation forestry (mostly planted) 61 Plantation forestry without felling 62 Plantation forestry with selective felling 63 Plantation forestry with clear felling
70 Agro-forestry 80 Nature protection 90 Other (explain)
Further information: Is hunting allowed? (Y/N/X; where X stands for no information) Is the wild life protected including density control? (Y/N/X; where X stands for no information) Is grazing by domesticated animals (e.g. cattle, pigs…) practised, or not? (Y/N/X; where X stands for no information)
2.5 Human influence
(modified from FAO, 2006) Any evidence of human activity, which is likely to have affected the landscape or the physical and chemical properties of the soil should be recorded (erosion is dealt with separately, see paragraph 2.16). Below are the most common examples of human influence listed. Observations of human impact on the soil profile is reported in chapter 3.20 (Man Made Materials) and 3.21 (Human Transported materials). Here only observations observed in the landscape on meso and micro scale are recorded.
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Code Description Code Description 1 No influence 15 Raised beds 2 Vegetation disturbed (not specified) 16 Terracing 3 Vegetation slightly disturbed 17 Land fill 4 Vegetation moderately disturbed 18 Levelling 5 Vegetation strongly disturbed 19 Artificial drainage 6 Mineral additions (not specified) 20 Irrigation (not specified) 7 Sand additions 21 Clearing 8 Organic additions (not specified) 22 Burning 9 Ploughing (not specified) 23 Surface compaction 10 Shallow ploughing (<20 cm) 24 Traffic traces 11 Ploughing (20-40 cm) 25 Application of fertilizers 12 Deep ploughing (>40 cm) 26 Pollution 13 Spitting (traces of spade marks) 30 Others (explain) 14 Plaggen
2.6 Vegetation
2.6.1 Forest type classification The forest type is described, according the European forest type classification, which was validated in the BioSoil biodiversity project of the majority o the Level I plots (EEA, 2007). On Level I, Level II and the Level II core plots, the forest type should be described in the general plot file (see Manual Part II).
2.6.2 Tree species composition The main tree species together with the type of tree species mixture (single tree wise mixture, group wise mixture, mixture by layers, etc.) is to be reported in the general plot file at the installation of the monitoring plot. See Manual Part II. The social class is mandatory to report on Level II for crown condition assessment.
2.7 Parent material
(originating from SG-DBEM, 2003) (to be reported in *.PRF file) The parent material is the material from which the soil has been derived. There are two groups of parent material: either unlithified materials (mostly sediments), or weathering materials overlying the hard rock from which they originate. There are also restored natural soil materials or sediments as well as man-made (technogenic) materials. The detailed table on parent material applied by the Soil Geographical Data Base (SG-DBEM, 2003) is presented in the explanatory items. The parent material should be described at least on the major class level. The 9 major classes summarised below are not listed hierarchically:
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Code Description of Major Class level 0000 No information 1000 Consolidated-clastic-sedimentary rocks 2000 Other sedimentary rocks (chemically precipitated, evaporated, or organogenic or biogenic in origin) 3000 Igneous rocks 4000 Metamorphic rocks 5000 Unconsolidated deposits (alluvium, weathering residuum and slope deposits) 6000 Unconsolidated glacial deposits / glacial drift 7000 Aeolian deposits 8000 Organic materials 9000 Anthropogenic deposits
2.8 Natural Drainage Classes
(Soil Survey Staff, 1993) Soil drainage is usually reflected by soil colour, but relict features may persist after natural or artificial changes in drainage. The depth of occurrence and intensity of gley features usually indicate the drainage status of the soil but not always: some soil materials will not develop strong features of gleying because of their specific chemical composition, texture, structure or porosity, other mottles may be the results of weathering minerals, rather than an impact of drainage conditions.
Code Class name Description 1 Excessively drained Water is removed from the soil very rapidly. Internal free (“gravitational”) water commonly is very rare or very deep. The soils are commonly coarse-textured, and have very high saturated hydraulic conductivity, or are very shallow. 2 Somewhat excessively Water is removed from soil rapidly. Internal free water drained occurrence commonly is very rare or very deep. The soils are commonly coarse-textured, and have high saturated hydraulic conductivity or are very shallow. 3 Well drained Water is removed from the soil readily, but not rapidly. Internal free water occurrence commonly is deep or very deep; annual duration is not specified. Wetness does not inhibit growth of roots for significant periods during most growing seasons. The soils are mainly free of the deep to redoximorphic features that are related to wetness. 4 Moderately well drained Water is removed from the soil somewhat slowly during some periods of the year. Internal free water commonly is moderately deep and may be transitory or permanent. The soil is wet for only a short time within the rooting depth during the growing season, but long enough that most mesophytic crops are affected. The soil commonly has a moderately low or lower saturated hydraulic conductivity within 1 m of the surface, or periodically receives high rainfall, or both. 5 Somewhat poorly drained Water is removed slowly so that the soil is wet at a shallow depth for significant periods during the growing season. Internal free water is commonly shallow to moderately deep and transitory to permanent. Unless the soil is artificially drained, the growth of most mesophytic plants is markedly restricted. The soil commonly has a low or very low saturated hydraulic conductivity or a high water table, or receives water from lateral flow, or persistent rainfall, or some combination of these factors.
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6 Poorly drained Water is removed so slowly that the soil is wet at shallow depths periodically during the growing season or remains wet for long periods. Internal free water is shallow to very shallow and common or persistent. Unless the soil is artificially drained, most mesophytic crops cannot be grown, unless the soil is artificially drained. The soil, however, is not continuously wet directly below ploughing depth (±25 cm). Free water at shallow depth is usually present. The water table is commonly the result of low or very low saturated hydraulic conductivity or persistent rainfall, or a combination of both factors. 7 Very poorly drained Water is removed from the soil so slowly that free water remains at or near the soil surface during much of the growing season. Internal free water is very shallow and persistent or permanent. Unless the soil is artificially drained, most mesophytic crops cannot be grown. The soils are commonly level or depressed and frequently ponded. If rainfall is persistent or high, the soil can be very poorly drained even on gentle slopes. X Not known
2.9 Water availability
(to be reported in *.PLS file) An estimate of the water availability to principal tree species during the growing season is made:
Code Description 1 Insufficient 2 Sufficient 3 Excessive
2.10 Period of water saturation
(FAO, 1990) In the description of drainage classes, the period when the soil is saturated or very wet is not satisfactory, especially where the rainfall is strongly seasonal or irregular. Very permeable sands may be permanently or seasonally waterlogged and impermeable clays may never be saturated or only for a few days a year. The period during which the soil near the surface is saturated should be indicated, based on local information or judgment supplemented by gleying features in the profile:
Code Description 1 Never saturated 2 Rarely saturated (a few days in some years) 3 Saturated for short periods in most years (up to 30 days) 4 Saturated for long periods every year 5 Always saturated
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2.11 External drainage
(FAO, 1990) The external drainage of a site refers to its relative position in the landscape. Is the site in a landscape position where it will overall receive water from upslope or rather shed water downslope? And if shedding, by which speed is the water lost? The following classes are defined:
Code Description 1 Ponded (run-on site) 2 Neither receiving nor shedding water 3 Slow run-off 4 Moderately rapid run-off 5 Rapid run-off
2.12 Flooding
(FAO, 1990) Flooding is described according to its frequency, duration and depth. At most sites it is difficult to assess flooding accurately. Information may be obtained from records of past flooding or from local enquiry. The frequency and duration classes give an indication of the average occurrence of flooding. It is very important to evaluate if the flooding is a relict or if it is still active at present.
2.12.1 Frequency
Code Description 1 Daily 2 Weekly 3 Monthly 4 Annually 5 Biennially 6 Once every 2-4 years 7 Once every 5-10 years 8 Rare (less than once in 10 years) 9 Inactive today, but has been active in historical time 10 Inactive today, but has once been active (ancient time) 11 None
2.12.2 Duration (days/year)
Code Description 1 Less than 1 day 2 1- 15 days 3 15- 30 days 4 30- 90 days 5 90 -180 days 6 180- 360 days
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2.12.3 Depth (of standing water)
Code Description Class limits 1 Very shallow 0 ‐ 25 cm 2 Shallow 25 ‐ 50 cm 3 Moderately deep 50 ‐ 100 cm 4 Deep 100 ‐ 150 cm 5 Very deep > 150 cm
2.13 Groundwater table
(Modified from SG-DBEM, 2003) The groundwater table level within or below a soil profile often varies in time. Therefore, the mean highest and mean lowest permanent or perched groundwater table level should be the average for at least the past 10 years. This information can in some cases be derived from maps. Seasonal variations are not recorded. The different groundwater table classes to be used are as follows:
2.13.1 Mean highest and mean lowest groundwater table (to be reported in *.PRF file) The mean highest and mean lowest permanent or perched groundwater table level is the average level for at least the past 10 years. Generally this information is lacking and so these values need generally to be estimated by an expert. The depth classes for groundwater for mean lowest and mean highest depth levels are:
Code Description Class limits 9 No water table observed or unknown 1 Very shallow to shallow 0 - 50 cm 2 Moderately deep 50 - 100 cm 3 Deep 100 - 150 cm 4 Very deep 150 - 200 cm 5 Extremely deep >200 cm
2.13.2 Type of water table (to be reported in *.PRF file)
Code Description 9 No water table 1 Perched water table (= stagnating water table) 2 Permanent water table ( = groundwater table)
2.14 Rock outcrops
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plot in order to make a correct estimate. The classes of percentage of surface cover and of average distance between rock outcrops (single or clusters) are as follows:
2.14.1 Surface cover
Code Description Class limits 1 None 0 % 2 Very few 0 - 2 % 3 Few 2 - 5 % 4 Common 5 - 15 % 5 Many 15 – 40 % 6 Abundant 40 – 80 % 7 Dominant >80 % 8 Rock outcrops are present but mostly hidden below forest litter
2.14.2 Distance between rock outcrops
Code Description 1 >50 m 2 20 - 50 m 3 5 - 20 m 4 2 - 5 m 5 <2 m
2.15 Coarse surface fragments
(FAO, 2006) Coarse surface fragments, boulders and stones, including those that are partly buried, should be described in terms of percentage of surface cover and size of the fragments. It is often not easy to observe boulders and stones under forest due to the litter layer, so a careful survey may be necessary. Remember, a stone or boulder partly buried is only included in the coverage and class estimate based on the visible part, it is not the purpose to uncover partly or completely buried coarse fragments. The classes of coverage and size handled are:
2.15.1 Surface cover
Code Description Class limits 9 None 0 % 1 Very few 0 - 2 % 2 Few 2 - 5 % 3 Common 5 - 15 % 4 Many 15 - 40 % 5 Abundant 40 - 80 % 6 Dominant >80 %
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2.15.2 Size classes Size classes according to the greatest dimension of the individual gravels/stones:
Code Description Class limits 1 Fine gravel 0.2 - 0.6 cm 2 Medium gravel 0.6 - 2.0 cm 3 Coarse gravel 2 - 6 cm 4 Stones 6 - 20 cm 5 Boulders 20 - 60 cm 6 Large boulders 60 - 200 cm
2.16 Erosion & sedimentation
(modified from FAO, 2006) Although under most forest covers erosion and sedimentation will be of minor importance, these variables have been included in these guidelines. Since, when it is present, it is of great importance for the soil formation and dynamics.
2.16.1 Type of erosion/sedimentation Erosion and sedimentation can be described according to the agency - water, wind, mass movements (landslides and related phenomena). In forested sites the major or only erosion may occur along patches, roads, timber tracks etc. Description should also include deposition of transported material:
Code Description 9 No evidence of erosion 1 Water erosion and sedimentation 2 Sheet erosion by water 3 Rill erosion by water 4 Gully erosion by water 5 Tunnel erosion by water 6 Mass movement (landslides and similar phenomena) 7 Sedimentation by water 8 Wind erosion and sedimentation 9 Sedimentation by wind 10 Shifting sands 11 Salt deposition 12 Other erosion/sedimentation, related to human
2.16.2 Area affected The proportion of total area affected by erosion/sedimentation is estimated:
Code Description 9 0 % 1 0 - 5 % 2 5 - 10 % 3 10 - 25 % 4 25 - 50 % 5 > 50 %
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2.16.3 Degree It is difficult to define classes of the degree of erosion which are equally appropriate for all soils, environments, and the various types of erosion. Classes may have to be defined further for each type or combination of erosion and sedimentation and each specific environment. For example, in the case of gully and rill erosion, the depth and spacing may be recorded; for sheet erosion the loss of topsoil; for dunes the height; for sedimentation the thickness of the layer. The following classes are recommended to describe the degree of erosion:
Code Class name Description 9 None No erosion nor sedimentation 1 Heavy sedimentation Soils buried below >50 cm of accumulated sediment 2 Considerable sedimentation Soils buried below 5 - 50 cm of accumulated sediment 3 Noticeable sedimentation Soils buried below <5 cm of accumulated sediment, continuously distributed 4 Traces sedimentation Soils buried below <5 cm of accumulated sediment, discontinuously distributed 5 Slight erosion Some evidence of damage to the topsoil; original biotic functions largely intact 6 Moderate erosion Removal of topsoil; original biotic functions partly destroyed 7 Severe erosion Surface layers completely removed and subsurface layers exposed 8 Extreme erosion Substantial removal of deeper subsurface horizons (badlands)
2.16.4 Activity The period of activity of accelerated erosion, or sedimentation, may be described as follows:
Code Description 9 Accelerated and natural erosion not observed 1 Period of activity not known 2 Active in historical times 3 Active in recent past (up till past 50 - 100 years) 4 Active at present
2.17 Surface sealing
(FAO, 2006) Where the mineral soil is exposed, a surface crust may develop. Only in extreme cases a surface sealing will develop on forest soils, as the soil should be exposed to wetting and drying and not be protected by a litter layer. If surface crusts develop it will have a negative effect on seed germination, reduce water infiltration and increase run-off. The thickness and the consistence of the crust is described (for consistence definitions see paragraph 3.11):
2.17.1 Thickness
Code Description Class limits 9 None 1 Thin <2 mm 2 Medium 2 - 5 mm 3 Thick 5 - 20 mm 4 Very thick >20 mm
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2.17.2 Consistence when dry
Code Description 1 Slightly hard 2 Hard 3 Very hard 4 Extremely hard
2.18 Surface cracks
(FAO, 2006) Mineral surface cracks develop in many clay-rich soils during drying. The width (average, or average width and maximum width) of the cracks, and the average spacing between cracks are measured.
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2.18.1 Size (Width)
Code Description Class limits 1 Fine <1 cm 2 Medium 1 ‐ 2 cm 3 Wide 2 ‐ 5 cm 4 Very wide 5 ‐ 10 cm 5 Extremely wide >10 cm
2.18.2 Distance between cracks
Code Description Class limits 1 Very closely spaced <0.2 m 2 Closely spaced 0.2 ‐ 0.5 m 3 Moderately widely spaced 0.5 ‐ 2 m 4 Widely spaced 2 ‐ 5 m 5 Very widely spaced >5 m
2.19 Salt
(FAO, 2006) The occurrence of surface salt may be described in terms of cover and appearance. Classes for the percentage of surface cover and thickness are:
2.19.1 Cover
Code Description Class limits 9 None 0 - 2 % 1 Low 2 - 15 % 2 Moderate 15 – 40 % 3 High 40 – 80 % 4 Dominant >80 %
2.19.2 Thickness
Code Description Class limits 1 Thin <2 mm 2 Medium 2 - 5 mm 3 Thick 5 - 20 mm 4 Very thick >20 mm
2.20 Profile depth
(to be reported in *.PRF file) The depth of the soil is defined with 3 attributes: effective rooting depth, rock depth and obstacle depth. The depth must be given in cm from the top of the mineral soil surface.
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The ‘Effective rooting depth’ is defined as the depth of the soil at which root growth is strongly inhibited. As rooting depth is plant specific, it is recommended that representative species are used to indicate the effective rooting depth of the soil. The effective rooting depth is governed by such factors as the presence of cemented, toxic or compacted layers, hard rock, or indurated gravel layers. A high permanent water table may also control the rooting depth, but may change after drainage. The effective hydrological depth may be much greater. Apart from obvious situations such as the presence of hard rock, it is realized that the estimation of effective soil depth is subject to individual interpretation. The depth to the underlying bedrock should be recorded under ‘Rock depth of the soil profile’. The field ‘Obstacle depth of the soil profile’ can be used to record the depth to any other limiting horizon, such as a petrocalcic horizon, fragipan, duripan, waterlogging, accumulation of toxic elements.
3. Soil horizon description
In the following chapter, the horizon variables are presented. The sequence is different from those presented in the FAO guidelines (FAO 1990; FAO 2006). Usually a forest soil is composed of mineral and organic horizons, stones, bedrock etc., which together constitute the soil profile. In the following chapter a series of variables are listed, but not all of them are equal relevant to particular organic horizons. For the definitions of organic material and organic horizons, see Annex 7. In principle knowledge of the content of organic matter is required to differentiate between organic and mineral materials. In the field, organic horizons are usually easy to recognise, only border cases will need analytical data to check for the content of organic carbon. In the table below the subchapters relevant for organic and mineral horizons are summarised:
Relevant for: organic horizons mineral horizons 3.1 Horizon boundary Yes Yes 3.2 Photographic recordings Yes Yes 3.3 Soil Colour Yes Yes 3.4 Mottling No Yes 3.5 Redoximorphic properties Yes Yes 3.6 Texture No Yes 3.7 Rock fragments Yes Yes 3.8 Andic material No Yes 3.9 Soil structure No Yes 3.10 Consistence No Yes 3.11 Cutanic features No Yes 3.12 Porosity Yes Yes 3.13 Cementation and compaction No Yes 3.14 Nodules No Yes 3.15 Roots Yes Yes 3.16 Other biological features Yes Yes 3.17 Carbonates Yes Yes 3.18 Gypsum No Yes 3.19 Readily soluble salts Yes Yes 3.20 Man made materials Yes Yes 3.21 Human transported material No Yes 3.22 Soil horizon designation Yes Yes
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After having selected the most representative location for the soil profile (see also Annex 3), the profile is opened and cleaned. A list of suggested field equipment is presented in Annex 4. The recommended sequence of description is as follows: delineation and description of the horizon boundaries, photographic recordings of the soil in general and of special features in detail, colour measurements (see also Annex 5), from this stage on, the profile wall is gently broken apart to record texture, rock fragments, structure, consistence, porosity, cutans, cementations and nodules, this is followed by the description of roots and other biological activity, and by the description of carbonates, gypsum and salts, each horizon is designated one or more horizon master and subordinate symbols, and the necessary samples are collected.
3.1 Horizon boundary (modified from FAO, 2006)
The nature of the boundaries between soil layers, or horizons, may indicate the processes that have formed the soil. In some cases, they reflect anthropogenic impacts. Horizon boundaries are described in terms of depth, distinctness and topography.
3.1.1 Horizon number (to be reported in *.PFH file) After delineation of the horizon boundaries, each horizon is numbered: 1, 2, 3 etc. While the horizon symbols may change according to new information, the horizon number is not to be changed at any point of the further profile description and sampling. The numbering starts from the interface between air and soil no matter whether the surface horizon is an organic or a mineral horizon (see Figure 3). If at a later stage, a new horizon is discovered or an existing horizon is subdivided, a new number should be created. Avoid renumbering of the existing horizons to keep the link with the initial description in the field.
3.1.2 Depth of horizon limits (to be reported in *.PFH file) The depth of the upper and lower boundary of each horizon is measured in centimetres from the surface of the mineral soil. If the soil is covered by (an) organic layer(s), either: a. 10 cm or more thick from the soil surface to a lithic or paralithic contact, or b. 40 cm or more thick, then the depth is measured from the surface of the organic cover. The depth requirements correspond to the limit for Histosols (organic soils).
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Figure 3: Examples on how the horizon depth should be recorded in the field. These depths are important for the profile description and for the sampling. Depth H1: OL -7-0 cm Depth H1: OL +30-26 cm H1:H 0-42 cm H2: H 0-42 cm H2: OH +26-0 cm Depth H1: A 0-12 cm H3: A 0-12 cm H2: A 42-54 cm H3: A 42-54 cm H2: E 12-20 cm H4: E 12-20 cm H3: E 54-62 cm H4: E 54-62 cm
H3: B 20-70 cm H5: B 20-70 cm H4: B 62-112 cm H5: B 62-112 cm
H4: C 70-100 cm H6: C 70-100 cm H5: C 112-142 cm H6 C 112-142 cm
If the organic layer(s) is (are) too shallow to fulfil the above depth requirement(s), then its depth is recorded from the zero-point and upwards (see Figure 3), using negative depths. The depth is measured perpendicular to the slope. Most soil boundaries are zones of transition rather than sharp breaks. The distinctness together with the topography describe the transition between the different horizons and substitute for the need to describe the depth ranges as for instance from 28 (25-31) cm to 45 (39-51) cm.
3.1.3 Distinctness (to be reported in *.PFH file) The distinctness of the lower horizon boundary refers to the thickness of the boundary zone in between adjacent horizons.
Code Description Class limits 3 Abrupt 0 ‐ 2 cm 4 Clear 2 ‐ 5 cm 5 Gradual 5 ‐ 15 cm 6 Diffuse >15 cm Concerning the boundary between the organic (as in forest floors) and the organo-mineral horizons, following classes of distinctness shall be used:
Code Distinctness Class limits 7 very sharp < 0.3 cm 8 sharp ≥ 0.3 and < 0.5 cm 9 not sharp ≥ 0.5 cm
3.1.4 Topography (to be reported in *.PFH file) The topography of the boundary indicates its shape (see Figure 4).
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Code Class name Description 1 Smooth Nearly plane surface 2 Wavy Pockets shallower than they are wide 3 Irregular Pockets deeper than they are wide 4 Broken Discontinuous 5 Complex
Figure 4: Illustration of the most common horizon topographies, which is the lateral undulation and continuity of the boundary between horizons (after Schoeneberger et al., 2002)
3.2 Photographic recordings
Quality photographs are essential for the soil database. A scale is needed on all photos, preferentially a bicoloured centimetre-scale. The use of tools for scaling should be avoided. If a tool e.g. a spade is used anyway the length of the spade should be clearly stated in the photo legend. Partly shade partly sunshine on the profile wall should be avoided. You may use a dark and uniform coloured umbrella to shade the profile. If possible avoid the use of a camera flash by using a tripod or a monopod. If an analogue camera is used, try always to use the same brand of film rolls. If using a digital camera, use a high resolution (5 Mega Pixels or more) and a camera with a good quality lens. The photographic database can/should include following images: General photo illustrating the geomorphology and vegetation of the area surrounding the profile Photo of the immediate vicinity of the profile The profile after cleaning and before indication of the soil horizons on the profile wall. The profile after the soil horizons are outlined gently on the profile wall with e.g. a knife The profile with partly visible structure and partly with a cleaned surface The profile with indications where to sample Close-up of the organic topsoil horizon(s) Horizontal sections, e.g. in de depths where the bulk density (BD) is sampled Special features 144 www.icp-forests.org/Manual.htm
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3.3 Soil colour
(to be reported in *.PFH file) The colour of the soil matrix in each horizon should be recorded in moist and dry condition using the Munsell notation (e.g. Munsell, 2000). The colour notation is composed of hue, value and chroma. Hue is the dominant spectral colour (red, yellow, green, blue, violet), value is the lightness or darkness of colour ranging from 1 (dark) to 8 (light), and chroma is the purity or strength of colour ranging from 1 (pale) to 8 (bright). If there is no dominant colour, the horizon is described as mottled and two or more colours are given, making use of the observation field. In addition to the colour notations, the standard Munsell colour names should be recorded as well. Example: Greyish brown 10YR 5/2 (moist) and light brownish grey 10YR 6/2 (dry); where 10YR (yellowish red) is the hue, 5 (or 6) is the value and 2 the chroma. Example: Dark greyish brown to greyish brown 2.5Y 4.5/2 (moist) and light brownish grey 2.5Y 6/2 (dry); Notice that interpolation between colours is possible for hue, value and/or chroma Example: Dark greenish grey 5GY 4/1 (moist) and greenish grey 10GY 5/1 (dry); where 5GY or 10GY (greenish yellow) is the hue, 4 (or 5) is the value and 1 is the chroma. More detailed information about optimal colour measurements and special colours required for soil classification is to be found in Annex 5.
3.4 Mottling
(FAO, 2006) Mottles are spots of different colours interspersed with the dominant colour of the soil. They commonly indicate that the soil has been subject to alternate wet (reducing) and dry (oxidizing) conditions. Other mottles can be the result of rock weathering, clay (+iron) migration and accumulation, selective decay by fungi of organic matter etc. Mottling is described in terms of abundance, size, contrast, boundary and colour. In addition, the shape, position or any other feature may be recorded.
3.4.1 Colour Measure the colours using the Munsell Soil Colour Charts. If the colour changes after exposure to the air, measure both the colours before and after oxidation.
3.4.2 Abundance Abundance is described as an exact figure or in classes indicating the percentage of the exposed surface occupied by the mottles. When mottles are so abundant that distinction of matrix and mottle colour is not possible, the predominant colours should be described as soil matrix colours.
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Code Description Class limits 1 None 0 % 2 Very few 0 ‐ 2 % 3 Few 2 ‐ 5 % 4 Common 5 ‐ 15 % 5 Many 15 ‐ 40 % 6 Abundant >40 %
3.4.3 Size The following classes are used to indicate the approximate diameters of individual mottles.
Code Description Class limits 1 Very fine < 2 mm 2 Fine 2 ‐ 6 mm 3 Medium 6 ‐ 20 mm 4 Coarse 20 ‐ 40 mm 5 Very coarse 40 ‐ 80 mm 6 Extremely coarse > 80 mm
3.4.4 Contrast The colour contrast between mottles and soil matrix can be described as:
Code Description 1 Faint: mottles are evident only on close examination. Soil colours in both the matrix and mottles are similar. 2 Distinct: although not striking, the mottles are readily seen. The hue, chroma or value of the matrix is easily distinguished from the mottles. They may vary by as much as 2.5 units of hue or several units in chroma or value. 3 Prominent: the mottles are conspicuous. Hue, chroma and value, alone or in combination, are several units apart.
3.4.5 Boundary The boundary between mottle and matrix is described according to the width of the transition zone.
Code Description Class limits 1 Sharp <0.5 mm 2 Clear 0.5 ‐ 2 mm 3 Diffuse 2 ‐ 5 mm 4 Very diffuse >5 mm
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3.5 Redoximorphic properties (IUSS Working Group WRB, 2007)
Redoximorphic features concerns a colour pattern observed in the soil, which is the result of depletion or concentration compared to the matrix colour, formed by oxidation/reduction of iron and/or manganese.
3.5.1 Reducing conditions If reducing conditions prevail in a soil horizon, it can be tested in following ways: 1. Is the negative logarithm of the hydrogen partial pressure (rH) less than 20? 2. Are Fe2+ ions present, as tested by spraying the freshly exposed soil surface with a 0.2% (m/v) α,α dipyridyl solution in 10% (v/v) acetic acid solution. The test yields a striking reddish colour in the presence of Fe2+ ions (be careful, the chemical is slightly toxic). Did a reddish colour (almost like red wine) appear on the tested soil surface after a few minutes? 3. Is iron sulphide present? 4. Is methane present? If the answer to any of above 4 questions is yes, report: Y If none of the test above are positive, report: N If data for some reason are missing or impossible to collect, indicate: X
3.5.2 Reductimorphic and oximorphic colours If oximorphic and/or reductomorphic mottles as present they are first of all described according to the chapter on mottles (see chapter 3.4). Note that gleyic mottles should be recorded as fast as possible after the profile has been prepared, sometimes even while digging the profile, due to the fast oxidation of certain minerals. Are reductimorphic colours, reflecting permanently wet conditions, present on more than 90% of the soil surface? Reductimorphic colours are neutral white to black (Munsell N1/ to N8/) or bluish to greenish (Munsell 2.5Y, 5Y, 5G, 5B). Y/N/X (Yes/No/Not known) Oximorphic colours reflect alternating reducing and oxidizing conditions, as is the case in the capillary fringe and in the surface horizons with fluctuating groundwater levels. They comprise any colour, excluding reductimorphic colours (see above). Are 5% or more of the soil surface cover by oximorphic coloured mottles? Y/N/X (Yes/No/Not known) The above described field tests may to some degree illustrate the actual redoximorphic conditions at the moment of fieldwork, rather than the general condition of the soil. For the same reason it is strongly recommended in case of gley soils to give special attention to: roots (presence/absence), and the soil water (indications of a fluctuating or permanent water tables etc.)
3.5.3 Stagnic and gleyic colour pattern Dending on the origin of the water, which is either the groundwater table, either surface water that is (at least temporarily) saturating the soil layer, two different colour patterns will develop. It is important to distinguish between both type of colour patterns during the profile description. version 5/2010 147
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Note: When a stagnic colour pattern is identified in a genetic horizon, it is designated by the horizon subordinate symbol ‘g’. When a gleyic colour pattern is seen, the horizon received the subordinate symbol ‘l’. See Annex 7. The latter symbol did not yet exist during the BioSoil demonstration project (Mikkelsen et al., 2006) and so is only applied in the ICP Forests programme from 2010 onwards.
Stagnic colour pattern
General description Soil materials develop a stagnic colour pattern (from Latin stagnare, to stagnate) if they are, at least temporarily, saturated with surface water (or were saturated in the past, if now drained) for a period long enough that allows reducing conditions to occur (this may range from a few days in the tropics to a few weeks in other areas). Diagnostic criteria A stagnic colour pattern shows mottling in such a way that the surfaces of the peds (or parts of the soil matrix) are lighter (at least one Munsell value unit more) and paler (at least one chroma unit less), and the interiors of the peds (or parts of the soil matrix) are more reddish (at least one hue unit) and brighter (at least one chroma unit more) than the non-redoximorphic parts of the layer, or than the mixed average of the interior and surface parts. Additional characteristics If a layer has a stagnic colour pattern in 50 percent of its volume the other 50 percent of the layer are non-redoximorphic (neither lighter and paler nor more reddish and brighter).
Gleyic colour pattern
General description Soil materials develop a gleyic colour pattern (from Russian gley, mucky soil mass) if they are saturated with groundwater (or were saturated in the past, if now drained) for a period that allows reducing conditions to occur (this may range from a few days in the tropics to a few weeks in other areas). Diagnostic criteria A gleyic colour pattern shows one or both of the following: 1. 90 percent or more (exposed area) reductimorphic colours, which comprise neutral white to black (Munsell hue N1/ to N8/) or bluish to greenish (Munsell hue 2.5 Y, 5 Y, 5 G, 5 B); or 2. 5 percent or more (exposed area) mottles of oximorphic colours, which comprise any colour, excluding reductimorphic colours. Field identification A gleyic colour pattern results from a redox gradient between groundwater and capillary fringe causing an uneven distribution of iron and manganese (hydr)oxides. In the lower part of the soil and/or inside the peds, the oxides are either transformed into insoluble Fe/Mn compounds or they are translocated; both processes lead to the absence of colours with a hue redder than 2.5 Y. Translocated Fe and Mn compounds can be concentrated in the oxidized form (Fe[III], Mn[IV]) on ped surfaces or in biopores (rusty root channels), and towards the surface even in the matrix. Manganese concentrations can be recognized by strong effervescence using a 10-percent H2O2 solution.
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3.6 Texture of the fine-earth fraction
(FAO, 1990) (to be reported in *.PFH file) Soil texture refers to the proportion of the various particle-size classes in a given soil volume and is described as soil textural classes (see Figure 5). The 2000 – 63 – 2 μm system for particle-size fractions is used. The names of the textural classes, which describe combined particle-size classes, are coded as in Figure 5. With a lot of training field estimates of the texture can be made, a method for finger testing of the textural classes is presented in Annex 6. Otherwise calculating the texture class based on the analytical data from pipette texture is recommended.
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Figure 1: The fine earth by size and defined in textural classes. Textural classes based on USDA (1951), adopted by FAO (1990) and refined by FAO (FAO, 2006)
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3.7 Rock fragments
(modified from FAO, 2006) Large fragments (>2 mm) are described according to abundance, size, shape, state of weathering and nature of the fragments. The abundance classes correspond with those for surface coarse fragments and mineral nodules.
3.7.1 Abundance (to be reported in *.PFH file) The abundance of rock fragments is estimated (Figure 6) and expressed as a percent (by volume) of the total soil. By preference, the exact figure is provided rather than abundance classes.
Code Description (FAO, 2006) Class limits (volume%) Description SGDBE (Lambert et al. 2003) 9 None 0 % No stones or gravel 1 Very few to few 0 ‐ 5 % Very few 2 Common 5 ‐ 15 % Few 3 Many 15 ‐ 40 % Frequent or many 4 Abundant 40 ‐ 80 % Very frequent, very many 5 Dominant >80 % Dominant or skeletal
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1 % 3 % 5 % 10 %
15 % 20 % 25 % 30 %
40 % 50 % 75 % 90 %
Figure 6: Charts for estimating proportions of coarse fragments, mottles or other elements
3.7.2 Size of rock fragments and artefacts
Code Description Class limits 1 Fine gravel 0.2 ‐ 0.6 cm 2 Medium gravel 0.6 ‐ 2 cm 3 Coarse gravel 2 ‐ 6 cm 4 Stones 6 ‐ 20 cm 5 Boulders 20 ‐ 60 cm 6 Large boulders 60 ‐ 200 cm
3.7.3 Dominant shape of rock fragments The shape may be described as:
Code Description 1 Flat 2 Angular 3 Sub‐rounded 4 Rounded
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3.7.4 State of weathering of rock fragments The state of weathering is described as:
Code Description 9 Fresh or slightly weathered: fragments show little or no signs of weathering 1 Weathered: partial weathering is indicated by discolouration and loss of crystal form in the outer parts of the fragments while the centres remain relatively fresh; fragments have lost little of their original strength. 2 Strongly weathered: all but the most resistant minerals are strongly discoloured and altered throughout; the fragments tend to disintegrate under hand pressure.
3.7.5 Nature (type) of rock fragments The nature of rock fragments is described by the same terminology as for the parent material.
3.8 Andic material
(modified from FAO, 2006) Soils formed from young volcanic materials often have andic properties: a bulk density of 900 kg/m3 or less, and <10 % clay with a smeary consistence (caused by allophane and/or ferrihydrite). Surface horizons with andic material are normally black because of the combination of allophane with humic material, or humic material immobilized by aluminium. Andic material may exhibit thixotropy, changing under pressure, or by rubbing, from a plastic solid into a liquefied stage and back into the solid condition. Is andic material present? Yes/No/Not known (reported as: Y/N/X)
3.9 Soil structure (modified from FAO, 2006)
Soil structure relates to the grouping or arrangement of soil particles into discrete soil units (peds). The aggregates are separated from each other by pores or voids and are characterised primarily on basis of their dominant shape: spheroidal (granular, crumb), platy, prism (columnar- top of the prisms are rounded and prismatic- top of the prisms are level) and blocky (angular blocky and subangular blocky).
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Pedogenic ped formation? no yes Carbonates Single Massive Layered Gypsum grain (coherent)(coherent) Formed by cementation from precipitates of Humus Iron Silica Formed by assemble Formed by separation Formed by fragmentation (biotic) (abiotic) or compaction
Worm- Blocky Blocky Granular casts subangular angular Prismatic Columnar Platy Crumbly Lumpy ClodyCloddy
Figure 7: Soil structure types and their formation (FAO, 2006)
With decreasing soil humidity, the soil structure becomes increasingly pronounced. In moist or wet conditions, if no clear structure is visible, a large lump of undisturbed soil material can be dried, which will possible reveal a specific structure. Another method is to take a large lump of soil on the spade and let it fall from about a meter height, and then to observe how the block of soil breaks into pieces. A third possibility is to use a knife to gentle loosen the soil material on the profile wall. Try to loosen the soil in such a way that it breaks along the natural ped faces rather than breaking through the peds (it demands a bit of practice). Besides the structure type, also grade and size of aggregates are recorded. When a soil horizon contains aggregates of more than one grade, size or type, the different kinds of aggregates should be described separately and their relationship indicated.
3.9.1 Type (to be reported in *.PFH file) The soil can be structureless or shows some kind of structure. If a structure is present the degree of development and the size characteristics to record. In structureless soil, no aggregates are observable in place and there is no definite arrangement of natural surfaces of weakness. Structureless soils are subdivided into single grain and massive (see Fgure 7).
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Figure 7: Absence of structure, either as single grain (left) or as massive (right) soil material (http://soil.gsfc.nasa.gov).
Structured soils:
Code Structure name Description 1 Platy Flat with vertical dimensions limited; generally oriented parallel to soil surface horizontally and, usually, overlapping with other structure types. 2 Prismatic The dimensions are greater in the vertical than horizontal direction; vertical faces well defined, having flat or slightly rounded surfaces which are casts of the faces of the surrounding aggregates. Faces normally intersect at relatively sharp angles 3 Columnar Structure are prisms with rounded caps instead of flat surfaces. 4 Angular Blocky Blocks or polyhedrons, nearly equidimensional, having flat surfaces which are casts of the faces of the surrounding aggregates. In an angular blocky structure, the faces intersect at relatively sharp angles. 5 Subangular blocky Same as 4 but with rounded faces. 6 Granular Spheroids or polyhedrons, having curved or irregular surfaces which are not casts of the faces of surrounding aggregates. Units do not fit into each other 7 Crumbs, lumps and Granular like pedality but with a very high inped porosity. Mainly created by artificial clods disturbance (e.g. tillage) (FAO, 2006). 8 Massive (coherent) Soil material (PT2) has normally a stronger consistence and is more coherent on rupture. Massive soil material may be further defined by consistence (see section 3.13). 9 Single grain Soil material (PT1) has a loose, soft or very friable consistence and consists on rupture of more than 50 % discrete mineral particles. 10 Wedge‐shaped Elliptical, interlocking lenses that terminate in sharp angles, bounded by slickensides; not limited to vertic materials. 11 Nutty Polyhedric blocky structure with many shiny ped faces which cannot or can only partially be attributed to clay illuviation 12 Rock structure Rock structure includes fine stratification in unlithified sediment, and pseudomorphs of weathered minerals retaining their positions relative to each other and to unweathered minerals in saprolite. 13 Worm casts A worm cast or vermicast is a structure created by worms, typically on soils such as those on beaches, that gives the appearance of multiple worms. 14 Layered (coherent) The natural types of structure are defined as follows (Figure 8). More than one type in one horizon is possible.
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1-10 mm dia. 5-50 mm dia. 10-500 mm dia. 10-500 mm dia. 1-10 mm thickness
Figure 8: Illustrations of some of the most common types of soil structures. From left to right, these are granular, blocky, prismatic, columnar and platy (http://soil.gsfc.nasa.gov). The sizes indicated are the normal range, smaller or larger sizes are possible.
3.9.2 Size If a structure is present, the size should be determined. The size classes vary with structure type. For granular, crumble and blocky structures the general size is measured (they are more or less equidimensional), for prismatic, columnar and wedged structures the size classes refer to the measurements of the smallest dimension of the aggregate. For platy structures the thickness of the plates are important, but it is recommended to notice the orientation as well.
Structure Code Size class Crumbly/ Granular/Prismatic/ Platy Blocky Columnar/Wedge‐shaped (mm) (mm) (mm) 1 Very fine or thin < 5 < 10 < 1 2 Fine or thin 5 ‐ 10 10 ‐ 20 1 ‐ 2 3 Medium 10 ‐ 20 20 ‐ 50 2 ‐ 5 4 Coarse or thick 20 ‐ 50 50 ‐ 100 5 ‐ 10 5 Very coarse or thick > 50 100 ‐ 500 > 10 6 Extremely coarse ‐ > 500 ‐
3.9.3 Grade If the structure is not well developed it can be difficult to estimate the degree of development of the structure, especially if the moisture content is high. Observe if the structural units are well defined on all sides, or only on a few and how easy the units are separated from each other. Grades of structured soil materials are defined as follows:
Code Class Description 9 None Structureless, such as for single grain and massive. 1 Weak Aggregates are barely observable in place and there is only a weak arrangement of natural surfaces of weakness. When gently disturbed, the soil material breaks into a mixture of few entire aggregates, many broken aggregates, and much material without aggregate faces. 2 Moderate Aggregates are observable in place and there is a distinct arrangement of natural surfaces of weakness. When disturbed, the soil material breaks into a mixture of many entire aggregates, some broken aggregates, and little material without aggregates faces. Aggregates’ surfaces generally show distinct differences with their interiors. 3 Strong Aggregates are clearly observable in place and there is a prominent arrangement of natural surfaces of weakness. When disturbed, the soil material separates mainly into entire aggregates. Aggregates’ surfaces generally differ markedly from their interiors.
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3.10 Consistence
(FAO, 2006) Consistence refers to the degree of cohesion or adhesion of the soil mass - friability, plasticity, stickiness and resistance to compression. It depends on the amount and type of clay, organic matter and moisture content of the soil. For reference descriptions, consistence is required for the soil in dry, moist and wet (both stickiness and plasticity) state. If applicable, thixotropy may be recorded. For routine descriptions, the soil consistence is described in the natural moisture condition of the profile. Wet consistence can always be described, and moist conditions if the soil is dry, by adding water to the soil sample.
3.10.1 Consistence when dry This is determined by breaking the air-dried soil in the hand:
Code Class Description 9 Loose Non‐coherent. 1 Soft Very weakly coherent and fragile; breaks to powder or individual grains under very slight pressure. 2 Slightly hard Weakly resistant to pressure; easily broken between thumb and forefinger. 3 Hard Moderately resistant to pressure; can be broken in the hands but not between thumb and forefinger. 4 Very hard Very resistant to pressure; can be broken in the hands only with difficulty. 5 Extremely hard Extremely resistant to pressure; cannot be broken in the hands.
3.10.2 Consistence when moist This is determined by squeezing a mass of moist soil material:
Code Class Description 9 Loose Non‐coherent. 1 Very friable Soil material crushes under very gentle pressure, but coheres when pressed together. 2 Friable Soil material crushes easily under gentle pressure between thumb and forefinger, and coheres when pressed together. 3 Firm Soil material crushes under moderate pressure between thumb and forefinger, but distinct resistance is felt. 4 Very firm Soil material crushes under strong pressure; barely crushable between thumb and forefinger. 5 Extremely firm Soil material crushes only under very strong pressure; cannot be crushed between thumb and forefinger.
3.10.3 Consistence when wet Stickiness depends on water content and the extent to which soil structure is broken down. Wet consistence is described in terms of stickiness and plasticity. It should be assessed under standard conditions on a soil sample in which structure is completely destroyed and which contains just enough water to create maximum stickiness. Stickiness is the quality of adhesion of the soil to other objects, assessed by observing its adherence when pressed between thumb and finger. version 5/2010 157
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Code Class Description 9 Non sticky After release of pressure, practically no soil material adheres to thumb and finger. 1 Slightly sticky After pressure, soil adheres to both thumb and finger but comes off one or the other rather cleanly; it is not appreciably stretched when the digits are separated. 2 Sticky Soil adheres to both thumb and finger and tends to stretch and pull apart rather than pulling free. 3 Very sticky Soil adheres strongly to both thumb and finger and is decidedly stretched when they are separated. Plasticity is the ability of soil material to change shape continuously under stress and to retain the given shape on removal of stress. It is determined by rolling the soil into a wire about 3 mm in diameter, then bending the wire.
Code Class Description 9 Non plastic Will not form a wire. 1 Slightly plastic Wire can be formed but immediately breaks if bent; soil deformed by very slight force. 2 Plastic Wire can be formed but breaks if bent into a ring; slight to moderate force required for deformation of the soil mass. 3 Very plastic Wire formed and can be bent into a ring; strong force required for deformation of the soil.
3.11 Cutanic features
(FAO, 2006) This section describes clay or mixed-clay illuviation features, coatings of other composition such as calcium carbonate, manganese, organics or silt; reorientations such as slickensides and pressure faces, and concentrations associated with surfaces but occurring as stains in the matrix (hypodermic coatings). All these features are described according to their type, abundance, contrast, and location.
3.11.1 Type The type of coatings may be described, following Schoeneberger et al. (2002), as:
Code Description 1 Clay 2 Iron oxides (sesquioxides) 3 Clay and iron oxides (sesquioxides) 4 Clay and humus 5 Humus 6 Silt coatings 7 Sand coatings
8 Calcium carbonate [CaCO3] 9 Silica (opal) [SiO2∙nH2O] 10 Gibbsite [Al(OH)3] 3+ Jarosite [KFe 3(OH)6(SO4)2]
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11 Manganese oxide [Mn2O3] 12 Pressure faces 13 Shiny faces 14 Slickensides2, predominantly intersecting 15 Slickensides, partly intersecting 16 Slickensides, non‐intersecting
3.11.2 Abundance For coatings (cutans), an estimate is made how much of the faces of soil aggregates, stones, or pores is covered. Similarly, the proportion of the soil layer occupied by lamellae is estimated.
Code Description Class 9 None 0 % 1 Very few 0 ‐ 2 % 2 Few 2 ‐ 5 % 3 Common 5 ‐ 15 % 4 Many 15 ‐ 40 % 5 Abundant 40 ‐ 80 % 6 Dominant >80 %
3.11.3 Contrast
Code Class Description 1 Faint Surface of coating shows little contrast with the adjacent surface. Fine sand grains are readily apparent in the coating. Lamellae are less than 2 mm thick. 2 Distinct Surface of coating is smoother than, or different in colour from the adjacent surface. Fine sand grains are enveloped but their outlines are visible. Lamellae are between 2 and 5 mm thick. 3 Prominent Surface of coating contrasts strongly in smoothness or colour with the adjacent surface. Outlines of fine sand grains are not visible. Lamellae are more than 5 mm thick.
3.11.4 Location The location of the coatings is indicated. For pressure faces and slickensides no location is given since they are, by definition, located on the faces of structural aggregates (ped faces).
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Code Description 9 No specific location 1 Ped faces 2 Horizontal ped faces 3 Vertical ped faces 4 Bridges between sand grains 5 Lamellae (clay bands) 5 Voids 6 Coarse fragments If the coatings are associated with coarse fragments, following subdivision can be made:
Code Description 7 Above stones 8 Below stones 9 All around stones
3.12 Porosity
(simplified from FAO, 2006) (to be reported in *.PFH file) Voids are related to the arrangement of the primary soil constituents and aggregates. They are the results of rooting, burrowing of animals and other soil forming processes such as cracking, translocation, leaching. The term void includes all air and water-filled spaces in the soil; the term pore is often used in a more restrictive way and does not include fissures or planes. For many purposes, a qualitative description of porosity will suffice. For reference descriptions, voids are described in terms of type, size and abundance; continuity and orientation may also be recorded. The porosity is an indication of the total volume of voids discernible with a x10 hand lens assessed by area and recorded as the percentage of the surface occupied by pores.
Code Description Class limits 1 Very low <2 % 2 Low 2‐5 % 3 Medium 5 – 15 % 4 High 15 – 40 % 5 Very high > 40 %
3.13 Cementation and compaction
(modified from FAO, 2006) The occurrence of cementation or compaction, as pans or otherwise, is described according to their nature, continuity, structure, agent and degree. Cemented material does not slake after one hour of immersion in water.
3.13.1 Nature (type) The cementing agent or compaction activity composes of:
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Code Description 1 Gypsum 2 Silica 3 Carbonates 4 Iron oxides 5 Iron‐manganese oxides 6 Iron‐organic matter 7 Organic matter 8 Others 9 Not known
3.13.2 Continuity
Code Class Description 1 Broken The layer is less than 50 % cemented/compacted and appears irregular 2 Discontinuous The layer is 50 ‐ 90 % cemented/compacted and appears regular 3 Continuous The layer is more than 90 % cemented/compacted, and has few cracks only
3.13.3 Structure The structure (or fabric) of the cemented/compacted layer may be described as:
Code Class Description 9 None Massive without recognizable orientation 1 Platy The cemented/compacted parts are plate‐like with more or less horizontal orientation 2 Vesicular The layer has large, equidimensional voids which may be filled with uncemented material 3 Pisolithic The layer is composed of cemented, spherical nodules 4 Nodular The layer is composed of cemented nodules or concretions of irregular shape
3.13.4 Degree
Code Class Description 9 Non‐cemented and No compaction/compaction is observed (slakes in water) non‐compacted 1 Compacted Compacted soil material is harder or more brittle than non‐compacted soil material. Non‐cemented. 2 Weakly cemented Cemented mass is brittle and hard, but can be broken in the hands 3 Moderately Cemented mass cannot be broken in the hands but is discontinuous (less cemented than 90 % of soil mass) 4 Cemented Cemented mass cannot be broken in the hands and is continuous (more than 90 % of soil mass) 5 Indurated Cemented mass cannot be broken by body weight (75 kg standard soil scientist) (more than 90% of soil mass)
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3.14 Nodules and other mineral concentrations
(FAO, 2006) Mineral nodules cover a large variety of secondary concentrations. There are gradual transitions with mottles. Nodules are described according to their kind, type, abundance, size, shape, hardness and colour, as well as their presence within the horizon:
3.14.1 Kind
Code Class Description 1 Crystal 2 Concretion A discrete body with a concentric internal structure, generally cemented 3 Soft segregation Differs from the surrounding soil mass in colour and composition but is not easily separated as a discrete body 4 Nodule Discrete body without an internal organization 5 Pore infillings Including pseudomycelium of carbonates and opal 6 Crack infillings 7 Residual rock fragment Discrete body still showing rock structure
3.14.2 Type Nodules are described according to their composition or impregnating substance. Examples:
Code Description 1 Gypsum 2 Silica 3 Carbonates 4 Carbonates‐silica 5 Salt 6 Clay 7 Clay‐oxides 8 Manganese oxides 9 Iron‐manganese oxides 10 Iron oxides 11 Sulphur 12 Not known
3.14.3 Abundance (by volume)
Code Description Class limits 9 None 0 % 1 Very few 0 ‐ 2 % 2 Few 2 ‐ 5 % 3 Common 5 ‐ 15 % 4 Many 15 ‐ 40 % 5 Abundant 40 ‐ 80 % 6 Dominant > 80 %
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3.14.4 Size
Code Description Class limits 1 Very fine < 2 mm 2 Fine 2 ‐ 6 mm 3 Medium 6 ‐ 20 mm 4 Coarse > 20 mm
3.14.5 Shape
Code Description 1 Rounded (spherical) 2 Elongated 3 Flat 4 Irregular 5 Angular
3.14.6 Hardness
Code Class Description 1 Hard Cannot be broken between the fingers 2 Soft Can be broken between forefinger and thumb nail 3 Both hard and soft
3.14.7 Colour General colour names are usually sufficient to describe nodules, in the same way as mottles:
Code Description 1 White 2 Yellow 3 Yellowish red 4 Reddish yellow 5 Red 6 Yellowish brown 7 Reddish brown 8 Brown 9 Green 10 Blue 11 Bluish‐black 12 Grey 13 Black 14 Multicoloured
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3.15 Roots
3.15.1 Abundance (FAO, 2006) (to be reported in *.PFH file) Presence/absence of roots is the most essential information to take notice of. A qualitative description of the size and the abundance of roots is important. Remember the abundance of roots should only be compared within the same size class. Abundance (number of roots/dm2) per size class:
Code Size class Very fine Fine Medium Coarse <0.5 mm 0.5‐2 mm 2‐5 mm >5 mm Abundance 9 None 0 0 0 0 1 Very few 1 ‐ 20 1 ‐ 20 1 ‐ 2 1 ‐ 2 2 Few 20 ‐ 50 20 ‐ 50 2 ‐ 5 2 ‐ 5 3 Common 50 ‐ 200 50 ‐ 200 5 ‐ 20 5 ‐ 20 4 Many >200 >200 >20 >20
3.15.2 Distribution If there is a sudden change in the quantity and/or size of the roots it is very important to explain why. Possible root limiting factors are: compaction (check the bulk density), cementations, discontinuous pore system, etc. Sometimes it may be useful to record additional information, such as an abrupt change in root orientation.
Code Description 1 Continuous 2 in the space of cracks 3 in the space of vughs and channels 4 concentrated in nests
3.16 Other biological features
(FAO, 2006) Krotovinas (an animal burrow which has been filled with material from another horizon), termite burrows, insect nests, worm casts, burrows or other disturbances of larger animals are described in terms of abundance and kind. In addition, specific locations, patterns, size, composition or any other characteristic may be recorded.
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3.16.1 Kind Examples of biological features are the following:
Code Description 1 Burrows (unspecified) 2 Open large burrows 3 Infilled large burrows 4 Earthworm channels 5 Termite or ant channels and nests 6 Other insect activity 7 Pedotubules3 (voids filled with soil material by faunal and floral activity, for further info read the footnote) 8 Charcoal
3.16.2 Abundance Abundance of biological activity is recorded as a percentage of the exposed surface: Code Description Class limits 1 Few <5% 2 Common 5‐15% 3 Many 15‐40% 4 Abundant >40%
3.16.3 Continuity Abundance of biological activity is recorded as a percentage of the exposed surface:
Code Description 1 Continuous 2 Discontinuous 3 Patchy 4 Locally 5 Other (explain)
3.17 Carbonates
(modified from FAO, 2006)
The presence of calcium carbonate (CaCO3) is indicated by adding some drops of 10% HCl to the soil. Following information should be collected per horizon:
3 The term pedotubules is proposed for a group of pedological features which have a tubular external form and which are distinguished from cutans by their complex internal composition and fabric. Pedotubules are classified according to their internal fabric and composition, details of external form, distinctness, and by a comparison of their fabric and composition with that of the horizons of the soil profile. Their general morphology suggests their origin as voids caused by faunal and floral (root) activity which have been filled, or partially filled, with soil material. Since little is known of the details of the effects of faunal activity on soil materials, such interpretations are tentative (Brewer and Sleeman, 1963) version 5/2010 165
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Is the matrix calcareous or non-calcareous (the exact quantity of carbonates will be tested in the laboratory). If traces are found in at least one horizon of the profile, the presence/absence should be recorded for all horizons. Is the carbonate at least partly secondary (pedogenic).
3.17.1 Presence of carbonates Following categories apply:
Code Description 9 No presence of carbonates 1 Matrix is non‐calcareous, presence of secondary carbonate 2 Matrix is calcareous, no evidences of secondary carbonate 3 Matrix is calcareous, presence of secondary carbonates
3.17.2 Type of secondary carbonates The type of secondary carbonates should be described. Following categories has been defined, more can be defined where applicable:
Code Description 1 Capping 2 Coatings 3 Nodules 4 Pendants 5 Pseudomycelia 6 Others (define)
3.18 Gypsum
(modified from FAO, 2006)
Gypsum (CaSO4•2H2O) may occur as residual, gypsous parent material or as newly formed features such as pseudomycelia, coarse crystals (commonly as nests, beards or coatings, or as elongated groups of fibrous crystals), or loose to compact powdery accumulations. Is gypsum present in the horizon? If so, where is it present (in the matrix, as nodules… …) and in which form is it present (crystals, powder,…; primary or secondary etc.). If gypsum is present in the soil, recommendations should be made for the laboratory on which samples the content of gypsum should be measured. The presence/absence of gypsum is explained applying following categories:
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3.18.1 Abundance of gypsum
Code Abundance (by volume) 9 0% 1 0 ‐ 5% 2 5 ‐ 15% 3 15 ‐ 25% 4 25 ‐ 60% 5 > 60%
3.18.2 Abundance of secondary gypsum
Code Abundance (by volume) 9 0% 1 0 ‐ 5% 2 > 5%
3.19 Readily soluble salts (modified from FAO, 2006)
Readily soluble salts are more soluble than gypsum; the most common salts are chlorides. The salt content of the soil can be estimated from the electrical conductivity (EC in dS/m = mS/cm) measured in a saturated soil paste or a more diluted suspension of soil/water. If salts are observed during fieldwork, the electric conductivity of a saturated paste should be analysed for all horizons in the soil. Is salt present? Y Evidences of soluble salts N No evidences of soluble salts X Not known
3.20 Man-made materials
(simplified from FAO, 2006) The areas dominated or significantly changed by human activity are rapidly extending, especially in urban and mining areas. Of particular importance are the man-made materials found in soils; their age, amount, state and composition determine their durability and environmental impact. Any human impact on the soil should be recorded. Examples are: Evidences of past agriculture Presence of artefacts (e.g. ceramics) Remains of past structures (e.g. postholes) Other features of possible human origin (e.g. charcoal, brick fragments)
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3.21 Human-transported material (simplified from FAO, 2006)
This is any material brought onto the site. This may be for agricultural purposes (e.g. large-scale terracing, mine spoil…), for human settlement, or simply to dispose of material (e.g. dredged sediment). It is a soil parent material in the same way as alluvium.
3.22 Soil horizon designation
The term horizon indicates a soil layer presumed to bear the imprint of soil forming processes, as opposed to layers that are laid down by sedimentation, volcanic activity or other geological events. Horizons are identified by symbols that consist of one or two capital letters for the master horizon and lower case letter suffixes for subordinate distinctions, with or without a figure suffix. The detailed definitions of the different horizon symbols and rules that apply are found in Annex 7. This annex also explains the use of symbols to express lithologic discontinuities and the vertical subdivision when two horizons have the same set of master and subordinate symbols.
3.23 References
AG-Boden (2004). KA5: Bodenkundliche Kartieranleitung (5th edition). W. Eckelmann, H. Sponagel, W. Grottenthaler, & K. J. Hartman. Schweizerbart: Hannover. (http://www.schweizerbart.de/pubs/isbn/bgr/bodenkundl-3510959205-desc.html)
Brewer, R. and Sleeman, J.R. (1963). Pedotubules their definition, classification and interpretation. European Journal of Soil Science 14 (1), 156–166.
Englisch, M., Katzensteiner, K., Jabiol, B., Zanella, A., de Waal, R. & Wresowar, M. 2005. An attempt to create a [Forest Floor] Classification key for BioSoil. Lecture notes presented on the 1st Training Course on WRB Soil Profile Description and Classification within the BioSoil Project. 3-7th October, 2005, Vienna.
FAO (1990). Guidelines for soil description (3rd edition). Soil Resources, Management and Conservation Service. Land and Water Development Division, Food and Agricultural Organization of the United Nations, Rome.
FAO. (2006). Guidelines for Soil Profile Description and Classification (4th edition) by R. Jahn, H.-P. Blume, V.B. Asio, O. Spaargaren and P. Schad (Eds) and by R. Langohr, R. Brinkman, F.O. Nachtergaele and P. Krasilnikov (Contributors), FAO, Rome.
FAO/ISRIC/ISSS, (1998). World Reference Base for Soil Resources. World Soil Resources Report, no. 84. FAO, Rome.
IUSS Working Group WRB, 2006. World reference base for soil resources 2006. World Soil Resources Report No. 103. FAO, Rome.
IUSS Working Group WRB, 2007. World reference base for soil resources 2006, first update 2007. World Soil Resources Report No. 103. FAO, Rome.
Langohr, R. (1994). Directives and rationale for adequate and comprehensive field soil databases. In: New waves in Soil Science. Refresher Course for Alumni of the International Training Centre for Post-Graduate Soil Scientists of the Gent University, Harare 1994. ITC-Gent Publications series 5, 176-191. 168 www.icp-forests.org/Manual.htm
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Mikkelsen, J. Cools, N., Langohr, R. (2006). Guidelines for Forest Soil Profile Description, adapted for optimal field observations within the framework of the EU Forest Focus Demonstration Project. BIOSOIL. Partly based on the 4th edition of the Guidelines for Soil Profile Description and Classification (FAO, 2006).
Munsell, (2000). Munsell Soil Color Charts. Gretagmacbeth, New Windsor, NY, US.
Ruhe, R.V. (1975). Geomorphology: geomorphic process and surficial geology. Houghton-Mefflin Co., Boston, MA, US.
Schlichting, H., Blume, P. & Stahr, K. 1995. Bodenkundliches Praktikum (2nd edition). Blackwell Science, Berlin.
Schoeneberger P.J., D.A. Wysocki, E.C. Benham and W.D. Broderson (Eds.) (2002). Field book for describing and sampling soils (version 2.0). Natural Resources Conservation Service, National Soil Survey Center, Lincoln, NE, US.
SG-DBEM. (2003). Soil geographical Database for Eurasia & the Mediterranean: Instruction Guide for Elaboration at scale 1:1,000,000 (version 4). J.J. Lambert, J. Daroussin, M. Eimberck, C. Le Bas, M. Jamagne, D. King & L. Montanarella (Eds.). European Soil Bureau Research Report No. 8, EUR 20422 EN, Office for Official Publications of the European Communities, Luxembourg.
Soil Survey Staff. (2003). Keys to Soil Taxonomy (9th edition). Natural Resources Conservation Service, United States Department of Agriculture, Washington, D.C.
UN-ECE, (2004). United Nations Economic Commission for Europe: Convention on Long-Range Transboundary Air Pollution. International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests. Manual on methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests. 4th edition 1998, updated June, 2004 (http://www.icp-forests.org/Manual.htm).
WGS84. World Geodetic System 84. http://www.wgs84.com/
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Annex 3: Recommendations for locating and describing a soil profile
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Location of the soil profile
The location of the soil profile should be as representative for the level plot as possible. Obviously only surface characteristics can help us in this search. Factors of importance can be: 1. Composition of ground vegetation, e.g. if most of the experimental plot hosts no ground vegetation do not locate the profile where vegetation is present 2. Composition of tree stand; dig the profile under the canopy of dominant tree species. 3. Avoid areas of strong human influence, such as ditches, earth banks, forest roads, tracks from tree harvesting machines… 4. Avoid micro-lows and micro-highs, as they will allow more or less litter to accumulate, which will have an influence on the biological activity and hydrology. 5. On experimental plots with steeper slopes, it is important to locate the profile as representative as possible with respect to the general slope inclination. If the general slope is concave or convex, then try to locate the profile at the level of the plot centre with respect to the slope (meaning in the zone immediate outside the experimental plot to the left or the right of this plot centre: not down- or upslope). 6. Other factors such as surface stoniness, rock outcrop, different land-use practice etc. should also be taken into consideration so that the profile location is as representative as possible.
Orientation of the soil profile
Factors to take into consideration are: 7. If the slope inclination is such that it will have an important impact on the hydrology, then the profile should be oriented with its long axe in the slope direction. 8. If the slope inclination is not important, the profile is oriented in such a way that by the time the profile is to be studied the light should be equally distributed over the complete profile wall (e.g. if you start to dig at 10 AM and you estimate that it takes 2h to dig the profile, and 30min to clean it for taking photos, then orient the profile towards SSW (180-200°). By the time you can take photos the profile will have a perfect angle towards the sun. A wall that is partly shaded partly with sunshine is impossible to describe optimally, and no quality photos can be produced. 9. If the slope and light is not a problem, then other factors can help with the orientation of the profile, such as microtopography, vegetation, etc. For example, if the experimental plot is characterised by drainage ditches, orienting the profile with its long axis perpendicular to the ditch will result in a profile where on the side walls it will be possible to observe the changes from a wetter soil closest to the ditch towards a drier soil between the ditches.
Observations to be made while digging the profile
10. If the field work is organised in such a way that the person that will do the profile description will be present when the profile is dug, it is advisable to make some first observations during this process. Following aspects of a standard profile description can by substantially improved if already considered during the profile digging, simply because the version 5/2010 173
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observations are made not only based on a two dimensional profile wall, but based on about one cubic metre of soil that is removed: 11. the rock fragments: description of the abundance, size, shape, and type is considerable improved, and special features such as presence/absence of pendants/cappings on the stones are better observed. I. Soil structure, especially type and degree of development II. Cutanic features, especially if the quantity is low working in a three dimension will improve the chance to observe such features III. Presence of cementations and compactions will undoubtedly be discovered when the profile is worked with the spade, shovel and pickaxe IV. If carbonate is present, observing if at least part of the carbonate is secondary will be easier V. Quantification and size estimates of roots, as well as the total root depth is more accurately observed
Observations in three dimensions
12. A standard profile is typically 80-100 cm wide, 180-200 cm long and should have a depth of 200 cm. The wideness and length can be reduced if e.g. the soil is very stony, but be careful not to diminish the profile beyond the size where proper use of spade, showel, pickaxe is restricted. The profile depth can be limited by a series of factors, such as: I. The groundwater table. If the permeability of the soil is low, digging below the groundwater table is possible and even soil sampling and/or making a few observations such as colour, reductomorphic properties, … is possible. Remember to measure the actual groundwater depth II. Bedrock, either continuous or discontinuous rock that prevents further digging III. Cementations of any kind, For example a Petrocalcic, Petroduric, Petrogypsic, Petroplinthic or Pisoplinthic cemented horizon which makes any further digging impossible. IV. Parent material. If the C horizon material is reached at a shallower depth than 200 cm, further digging can be stopped. It is though recommended to continue 20-50 cm to control that it indeed is the C-horizon that has been reached. 13. When the profile in its full length has reach a depth of about 100-120 cm, further digging is restricted to the 80-100 cm of the profile closest to the front wall. This creates a soil pit with 2 or more steps. 14. After digging the profile, it is essential to clean the profile walls. I. This is done by e.g. a knife, trowel, or another scraping tool with an metal blade, make sure that the metal blade has rounded edges to avoid sharp scraping lines on the profile wall. II. While the profile is cleaned, the soil is carefully observed, with respect to colours, presence absence of roots, biogalleries, stones and other characteristics that might be important to outline the horizons. III. Take the first round of photos (see paragraph 3.2 of Annex 2): Of the profile, details of the profile, and the surrounding landscape IV. Draw on the profile wall with the knife the horizon boundaries. The most important feature to delineate horizons from each other is change of colour. Other feature that can be used to differentiate genetic horizons from each other are a relatively sharp change over (vertical)
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distance of mottles, texture, coarse fragments, structure, porosity, cementation, compaction, nodules, roots or carbonates. V. A second round of photos ((see paragraph 3.2 of Annex 2) is taken of the profile with and without the horizon boundaries indicated, and of particular details such as mottles, involutions, biogalleries, disturbances etc. 15. If a soil is composed of well developed relatively uniform horizons, focussing on the front wall for the profile description is usually sufficient. If on the other hand the profile is more irregular and/or the horizons are less developed, it might be necessary to study also the side walls. This should appear from the profile description. For example the horizon depths in soil profiles located on a strong slope should be measured perpendicular to the surface, which is easiest on the side wall. 16. For certain pedological features, it might be useful to study them on a horizontal surface. This is for example possible while digging the profile, or when the first or second stair has been made at the correct depth. If necessary, a new sub-profile is dug on the sidewall to the depth(s) where a horizontal section is needed.
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Annex 4: Field equipment
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Equipment for profile Number Further information description: Spade, pickaxe 1 Shovel 2 Bucket 1 Scraper 1 Make the corners rounded to avoid sharp lines on the cleaned profile wall Trowel 1 Sharpen the edges to allow a better cutting in the soil Knife 1 The blade should be straight (e.g. to cut bulk density samples straight) and as long as possible (recommended is 15-20 cm) Field umbrella 1 To shade for sun and rain Pruner or horticulture sheer 1 To cut roots Small painting brush optional To highlight certain special features e.g. slickensides, stones, etc. Munsell Colour Chart 1 Try to avoid dirt on the colour chips Folding ruler or measuring 2 Two coloured ones are preferred tape Note book 1 Large enough e.g. A5 format, with squared lines on the paper to facility profile drawings Writing pen/pencil 2 Marker pen 2 For sample labelling, black colours are more resistant to sun light Sample labels sufficient Hand lens 1 Magnifications x10 (4 +6 or 2 + 8) Soil thermometer optional Especially if the soil at or below 0°C Penetration rod 1 Required if the soil is compacted, cemented or is stony Clinometer or Abney-level 1 To measure slope inclinations GPS system 1 Measuring coordinates of key points on the plot Compass 1 For orientation of e.g. slope direction Auger handle 1 Auger heads selection Selection in accordance to soil type, see table below Extension rods 1 With one extension a depth of 225 cm can be reach Photo camera and tripod 1 Water bottle 1 Water sprayer 1
For sampling Number Further information Sampling tray optional Sample recipients sufficient Quality bags (plastic, cloth..) or boxes Sample labels sufficient Sample frame 1 - 3 To sample the organic layer
For pF and BD Number Further information Bulk density cylinders sufficient Take care not to destroy the cutting edge of the ring while (volume between 100 cm3 inserting it into the soil and 250 cm3) and lids Ring holder optional Needed if the soil is hard (e.g. due to dryness and/or a high clay content) Impact free hammer 1 Eventually a geological hammer if fieldwork is done in version 5/2010 179
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mountainous regions Wood piece 1 To distribute the hammer impact equally Hammering head optional For very hard soils, to be used with the guide cylinder Cylinder guide optional Small iron saw 1 To cut the edges of the sampling rings
Liquids: Number Further information Distilled water* ±100 cl To test moist colours; testing for water repellence
Concentrated H2O2* ±100 cl Reacts to manganese (charcoal and organic matter not) 10% HCl* ±100 cl Reacts to carbonates α, α dipyridyl* ±100 cl Reddish colour reaction if Fe2+ is present Read also: http://soils.usda.gov/use/hydric/ntchs/tech_notes/note8.html * The liquids are by preference stored in bottles, which allow drop wise application (like eye drops). If this is not possible, bring along plastic pipettes for careful application.
Soil augers:
Soil texture Moisture condition Type of Edelman Riverside Gouge augers auger auger wet sand - - Sandy moist combi, sand (+) + dry sand - (+) wet Combi - + Loamy/silty moist Combi - + dry - + - wet Clay - + Clayey moist Clay - + dry - + - wet Gravel - - Stony moist Gravel - - dry - + - Frozen soil (gravel) (+) - "-" : not suitable "(+)" : possibly suitable "+" : suitable (recommended) Clay-auger: thin blades, good for clayey and/ sticky soils when moist and wet Combi-auger: all round auger best for medium textured soils when moist and wet Sand-auger: has wide blades, so the sand stays in the auger even if the soil is relatively dry Gravel-auger: with two cutting blades at the end that can drill and remove small stones Riverside-auger: closed with drilling blades, the only auger that can be used in dry loamy or dry clayey soils. It should be avoided when these soils are moist or wet! Sometimes also useful in frozen soils Gouge-auger: for non-stony soils preferentially moist or wet. It can take undisturbed samples. Mode length variable, mostly 50 to 100 cm long.
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For the sampling of the organic layer a frame of 25 by 25 cm is recommended, but alternatives with a minimum total surface of 500 cm2 are acceptable. For mor humus, an auger with a diameter of 8 cm can be used.
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Annex 5: Additional information on colour measurements
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This annex provide additional information on the colours, particular for optimal measurements for classification purposes (IUSS WG on WRB 2006, update 2007) Colour should be determined, if possible, under uniform conditions out of direct sunlight. Early morning and late evening readings are not accurate. Determination of colour has proven to be often inconsistent between individuals or, even for the same person. Since colour is significant with respect to many soil properties and for soil classification, routine cross-checks are recommended. To save time in the field and to improve the colour measurements, it is recommended to measure the colours in the laboratory. Let fragments of the soil air-dry before the dry colours are measured, then gently add vaporised water to moisten the sample to field capacity. The wet colour can be measured after saturation of the sample with water. Colours for waterlogged soils should be measured immediately before the soil gets oxidised. For all horizons, at least the moist colours should be recorded (if the soil is arid or wet, respectively dry and wet colours may replace the moist ones). In those soils where one or more diagnostic horizons or properties might be present, additional colours are mandatory as summarised in the table. For example, for a soil with a spodic horizon (diagnostic for Podzols), information on the moist crushed colour is required according to the WRB.
Table 4: Required colour measurements.
Soil Measured Horizons for which colours are required moisture colour O, H A EBC condition Dry Matrix (broken) 2a, 2b 453 Crushed 2a, 2b Moist Matrix (broken) 1 1, 2a, 2b 111 Crushed 2a, 2b 6 Wet Matrix 1b 1b 1b 1b 1b
1. Moist colours should always be recorded for all horizons in the profile, except for those soils that 1b) naturally are wet (e.g. Gleysols, Histosols). For those soils, the wet colours are measured instead of moist colours. The matrix colour can be considered the same as the broken colour. 2. 2a) Broken colours are mandatory to record if the soil has a dark topsoil with colours of 3.5/3.5 (value/chroma) or less when moist, and a value of 5.5 or darker when dry. 2b) If the soil may have aridic properties (relative low organic carbon content, evidences of aeolian activity, high base saturation…) these colour measurements are required too. 3. Should be measured if the topsoil has colours of 3.5/3.5 (value/chroma) or less when moist, and a value of 5.5 or darker when dry (see 2a). If no C-horizon is present, the colour should be measured for the horizon immediately underlying the surface horizon(s). 4. If the eluvial horizon has a colour value of 4 or more and a chroma of 4 or less, then measure also the dry colour. 5. If the moist colour is redder than 5YR (3.5YR or redder) then also the dry colour should be measured (required for the rhodic qualifier). 6. If the soil may have a spodic horizon (required for Podzols), then the crushed colour is mandatory to record. The colour required for a spodic horizon (moist) is 10YR or redder with value of 3 or less and chroma of 2 or less. If the colour is 7.5YR or redder the value required is 5 or less and the chroma 4 or less.
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Annex 6: Guidelines for field estimates of textural classes
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The textural class can be estimated in the field by feel. For this, the soil sample must be moist (as close as possible but not exceeding the field capacity). Fragments >2 mm must be removed.
Clay: Soil can be rubbed, is sticky, can be moulded but is stiff (high plasticity), smeared surface is shiny Silt: Soil can be rubbed, is non-sticky, and feels floury (like talc) Sand: Cannot be moulded, does not soil fingers and feels gritty
Key to the soil texture classes (adapted from Schlichting et al., 1995) y Cannot be rolled into a ball % clay Not dirty, not floury, no fine material adhering to fingers: sand S <5 If grain sizes are mixed: Unsorted sand US <5 If most grains are very coarse (>0.5 mm): very coarse and coarse sand CS <5 If most grains are of medium size (0.25-0.5 mm): medium sand MS <5 If most grains are of fine size (<0.25 mm) but still grainy: fine sand FS <5 If most grains are of very fine size (<0.1 mm), almost floury: very fine VFS <5 sand 2. Can be rolled into a ball but not into a wire Not floury, grainy, scarcely any fine material sticking to fingers, forms a LS <12 ball weakly, adheres slightly to the fingers: loamy sand As 2.1 but floury: sandy loam SL <10 3. Can be rolled into a wire of about 3 to 7 mm in diameter (about half the diameter of a pencil) but breaks when trying to bend into a ring, sticks to the fingers Floury and not cohesive Some grains to feel: silt loam SiL <10 Floury and not cohesive, no grains to feel: silt Si <12 Cohesive, sticks to the fingers, has a rough and smeared surface after squeezing between fingers Is very grainy and not sticky: sandy loam SL 10-25 Neutral feel, neither sticky, nor gritty, nor floury: loam L 8-27 Is not grainy but distinctly floury and somewhat sticky: silt loam SiL 10-27 Is very grainy and not sticky: sandy loam SL 10-25 Sticky and grainy to very grainy: sandy clay loam SCL 20-35 4. Can be rolled into a wire smaller than 3 mm in diameter (less than half of that of a pencil) and bent to form a ring of about 2-3 cm in diameter, cohesive, sticky, shiny smeared surface Very grainy: sandy clay SC 35-55 Grains can be seen and felt: clay loam CL 25-40 No grains to see and to feel, low plasticity: silty clay loam SiCL 25-40 No grains to see and to feel, high plasticity: silty clay SiC 40-60 5. Shiny smeared surface and high plasticity Some grains to see or to feel, grates between teeth: clay C 40-60 No grains to see or to feel, does not grate between teeth: heavy clay HC >60
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Annex 7: Detailed definitions, rules and conventions on master and subordinate horizon symbols
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1. Vocabulary
Organic material (OM) (IUSS Working Group WRB, 2007) (from Greek organon, tool) consists of a large amount of organic debris that accumulates at the surface under either wet or dry conditions and in which the mineral component does not significantly influence the soil properties. Diagnostic criteria. Organic soil material must have one of the two following: 1. 20 percent or more organic carbon (by mass) in the fine earth; or 2. if saturated with water for 30 consecutive days or more in most years (unless drained), one or both of the following: a. (12 + [clay percentage of the mineral fraction * 0.1] percent or more organic carbon in the fine earth (by mass), or b. 18 percent or more organic carbon (by mass) in the fine earth.
Organic horizons The organic horizons (codes: OL, OF, OH) are formed by dead organic matter (OM), mainly leaves, needles, twigs, roots and, under certain circumstances, materials such as mosses and lichens. This OM can mainly be transformed in animal faeces. An organic horizon contains 20 % or more organic carbon (by mass) in dry samples, without living roots.
Hemorganic horizons The hemorganic horizons (code: A) are formed near the soil surface, generally beneath the organic horizons. Coloured by organic matter, these horizons are generally darker than the underlying mineral part of the soil profile. It is generally accepted that in the soil fraction < 2mm of the A horizon, the organic carbon has to be less than 20% by mass (following WRB FAO 2006, Broll et al. 2006).
Recognisable remains Recognisable remains within an organic or hemorganic horizon are organic materials like leaves, needles, roots, bark, twigs and wood, fragmented or not, whose original organs are recognizable by the naked eye or with a 5-10 X magnifying hand lens. Fresh litter generally consists for 100% of recognizable remains (Zanella et al. 2010)
Humic components Humic components of an organic or hemorganic horizon are small particles of organic remains and/or grains of organic or organo-mineral matter mostly comprised of animal droppings of different sizes. The original organs which compose the litter and generate the small particles (free or incorporated in animal faeces) are not recognizable by the naked eye or with a 5-10 X magnifying hand lens. Bound mineral particles can be visible within the mass. Well decomposed organic substrate generally consists for 100% out of humic components. However, the generated humic component can also be in the hemorganic (A) and organic (OL, version 5/2010 193
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OF, OH) horizons. Thus, an A horizon made of anecic and endogeic earthworm hemorganic faeces as well as a totally, finely decomposed and mostly organic OH horizon resulting from enchytreid and microarthropod activities, can both be composed for 100% of humic components, despite differences in the animals responsible for the structure of the horizons (Zanella et al. 2010).
Fibric component Non-decomposed or very weakly decomposed hygrophilous plant remains like sphagnum species, sedges, rushes, reeds... Whole plants, parts of them and/or free plant organs (leaves, needles, twigs, wood, roots...) sometimes lying in more or less dark coloured layers.
Sapric component Homogeneous dark organic and organo-mineral matter comprised of well decomposed plant remains partly mixed with mineral particles. Plant structures are not visible to the naked eye or with a 5-10 X magnifying hand lens. Animal droppings are possible in periodically drained horizons and can be abundant in drained peats.
Mineral components Mineral components of an organic or hemorganic horizon are mineral particles of different sizes, free or very weakly bound to humic components and visible by the naked eye or with a 5-10 X magnifying hand lens.
Zoogenic transformed material Zoogenic transformed materials are recognizable remains and humic components processed by animals (i.e. leaves, needles and other plant residues more or less degraded by soil animals, mixed with animal droppings. A fine, powdered and/or grained structure (less than 1 mm) is typical in a terminal stage of faunal attack in an organic horizon. At this last level of biotransformation, the substrate (OH horizon) is essentially comprised of organic animal droppings of varying size (droppings of epigeic earthworms, macro-arthropods such as millipedes, woodlice and insect larvae, micro-arthropods such as mites and springtails and enchytraeids dominate). Within hemorganic horizons, animal activity leads to different types of A horizons, depending on the animals’ ability to dig into the mineral soil and thoroughly mix organic and mineral matter.
Non zoogenic transformed material Non zoogenic transformed materials are recognizable remains and humic component processed by fungi or other non-faunal processes (i.e. leaves, needles and other plant residues more or less fragmented and transformed into fibrous matter by fungi. Recognizable and recent animal droppings are absent or not detectable by the naked eye in the organic horizons; fungal hyphae can be recognized as white, brown or yellow strands permeating the organic or hemorganic substrates; traces of animal activity (old bite marks, mucus) may sometimes be detectable but are always marginal. In the last stage of biodegradation of an organic horizon, non zoogenic substance may essentially be composed of brown, dry plant residues more or less in powder form or tiny fragments (OF and OH horizons), or be massive like a dark wet plastic clay (OH or very organic A horizons). By the naked eye or with a 5-10 X magnifying hand lens, each topsoil horizon appears to be composed of recognizable remains, humic and mineral components (fig. 1). At the soil surface, 194 www.icp-forests.org/Manual.htm
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the animals or plant cover shed litter (remains) on and within the soil. Animal remains exist too, but they are quite negligible compared to plant remains and often overlooked by the neophyte. Litter is made up of recognizable residues and humic components (because of soil biological activity). In the other direction, the geological substrate “leaks” fragments of rock, which in the topsoil become mineral (free grains) and humic (grains incorporated in faeces) components. The mineral component can also be increased by surface erosion. The process perceived by the naked eye hides a more complex world of chemical-physical–biological processes. In unfavourable conditions for soil fauna the process is mainly dominated by fungi. Therefore, the new definitions of zoogenic and non zoogenic transformed material have been coined to distinguish zoogenic biological transformation from mycogenic transformation. The aim of a naked eye examination is to collect initial data and information for the purposes of a more detailed research on the same system. The vocabulary terms have been selected with regards to a dynamic interpretation of current knowledge on the topsoil.
2. Soil horizon designation
2.1 Master horizons and layers
2.1.1 The Organic horizons
2.1.1.1 O horizon or layer The O horizon or layer is dominated by organic material, consisting of fresh, partially or completely decomposed litter (such as leaves, needles, twigs, mosses, and lichens) that has accumulated on the surface; it may be on top of either mineral or organic soil. It is not saturated with water for prolonged periods. The mineral fraction of such material is only a small part of the volume of the material and generally is much less than half of the mass. An O layer may be at the surface of a mineral soil or at any depth beneath the surface if it is buried. However, a horizon formed by illuviation of organic material into mineral subsoil is not an O horizon (FAO, 2006). A subdivision of the organic O-layers is made according to the following definitions (Zanella et al. 2010): OL-horizon (Litter, Förna): this organic horizon is characterised by an accumulation of mainly leaves/needles, twigs and woody materials (including bark), fruits etc. This sublayer is generally indicated as litter (Klinka et al., 1981, Green et al., 1993, Jabiol et al., 1995, Delecour, 1980). It must be recognized that, while the litter is essentially unaltered, it is in some stage of decomposition from the moment it hits the floor and therefore it should be considered as part of the humus layer. There may be some fragmentation, but the plant species can still be identified. So most of the original biomass structures are easily discernible. Leaves and/or needles may be discoloured and slightly fragmented. The humic components amounts to less than 10 % by volume; recognisable remains 10% and more, up to 100% in non-decomposed litter. OL types (suffixes: n, v, t) OLn: new litter (age < 1 year), neither fragmented nor transformed/discoloured leaves and/or needles; version 5/2010 195
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OLv: old litter (aged more than 1 year, vetust, verändert, verbleicht), slightly altered, discoloured, bleached, softened up, glued, matted, skeletonized, sometimes only slightly fragmented leaves and/or needles. OLt: transitional (t) litter made of leaf petioles, twigs, bark and surface cast accumulation in very active mull forms (eumull generally in mixed hardwood forest – described in ash/beech stands). Note: The passage from OLn to OLv can be very rapid (1 to 3 months) or very slow (more than a year) according to types of litter (plant species composition), climate, season and level of soil biological activity OF-horizon (fragmented and/or altered) is a zone immediately below the litter layer. This organic horizon is characterised by an accumulation of partly decomposed (i.e. fragmented, bleached, spotted) organic matter derived mainly from leaves/needles, twigs and woody materials. The material is sufficiently well preserved to permit identification as being of plant origin (no identification of plant species).The proportion of humic components is between 10 % and 70 % by volume. Depending on humus form, decomposition is mainly accomplished by soil fauna (OFzo) or cellulose-lignin decomposing fungi (OFnoz). Slow decomposition is characterised by a partly decomposed matted layer, permeated by hyphae. Note: this is the fragmented layer in non-saturated soils (Klinka et al., 1981, Green et al., 1993, Jabiol et al., 1995, Delecour, 1980) OF types (suffixes: zo, noz) OFzo = content in zoogenic transformed material > 10% of the volume of the horizon; OFnoz = content in non zoogenic transformed material 90% or more of the volume of the horizon; OH-horizon (humus, humification): characterised by an accumulation of dark, well-decomposed, amorphous organic matter. It is partially coprogenic, whereas the F horizon has not yet passed through the bodies of soil fauna. The humified H horizon is often not recognized as such because it can have friable crumb structure and may contain considerable amounts of mineral materials. It is therefore often misinterpreted and designated as the Ah horizon of the mineral soil and not as part of the forest floor as such. To qualify as organic horizon, it should fulfil the FAO requirement, as described above. The original structures and materials are not discernible. Humic components amounts to more than 70 % by volume. The OH is either sharply delineated from the mineral soil where humification is dependent on fungal activity (mor) or partly incorporated into the mineral soil (moder). Note: This horizon coincides with what is called the humus layer (Klinka et al., 1981, Green et al., 1993, Jabiol et al., 1995, Delecour, 1980) OH types (suffixes: zo, noz, r, f) OHzo = content in zoogenic transformed material > 30% of the volume of the horizon; OHnoz = content in non zoogenic transformed material 70% or more of the volume of the horizon; Concerning the organic layers, a distinction is made between the water saturated organic layers, designated as ‘H’, and the aerated organic materials indicated as ‘O’.
2.1.1.2 H horizon or layer The H horizon or layer is dominated by organic material, formed from accumulations of fresh or partially decomposed organic material at the soil surface (which may be under water). All H horizons are saturated with water for prolonged periods or were once saturated but are now drained. A H horizon may be on top of mineral soils or at any depth beneath the surface if it is buried (FAO, 2006).
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Distinction of subhorizons in the organic H-layers (Zanella et al., 2010):
Hf (from Histic and fibric) horizon Histic organic horizon consisting almost entirely of almost unchanged plant remains. Fibric component ≥ 90%, sapric component < 10% of horizon volume. Content of rubbed fibres ≥ 40% of soil by dry weight (105 °C)4. Von Post scale of decomposition: 1 to 3 (4, 5 possible)5. Remarks: Plant remains from mosses like Sphagnum species, sedges, rushes and reeds are recognizable. Fibric horizons are quite common in bogs and oligotrophic parts of isolated fens. These horizons are mainly composed of remains of Sphagnum and Eriophorum species. In mesotrophic fens, the Hf-horizon is mainly composed of remains of sedges and rushes. Fibric horizons in eutrophic fens are less common because of the fast decomposition in those environments. A further differentiation could be made on the base of the origin of the plant material (oligotrophic mosses, mesotrophic sedges, mesotrophic sedges and reeds).This could be adapted to national, regional and local circumstances. Note: this horizon coincides with what is classified as fibric (Klinka et al., 1981, Green et al., 1993) or fibrist (Delecour, 1980).
Hfs (from Histic, between fibric and sapric) Histic organic horizon consisting of half decomposed organic material not fitting the definition of fibric (Hf) or sapric (Hs). Fibric component 10% to 70%, sapric component 90% to 30% by volume (Figure 9). Content of rubbed fibres 10 to 40% of soil by dry weight (soil dried at 105 °C), Von Post scale of decomposition: 4 to 7 (8 possible)6. Note: This horizon coincides with what is classified as mesic (Klinka et al., 1981, Green et al., 1993) or hemist layer in saturated soils;
4 The content (by mass) of the total organic fraction is generally more than 80%. When saturated, this fibric horizon can have a water content of far more than 850% of the oven-dry weight (Soil Taxonomy 1975). 5 von Post scale: (1) Undecomposed; plant structure unaltered; yields only clear water coloured light yellow brown; (2) almost undecomposed; plant structure distinct; yields only clear water coloured light yellow brown; (3) very weakly decomposed; plant structure distinct; yields distinctly turbid brown water, no peat substance passes between the fingers, residue not mushy. 6 von Post scale: (4) weakly decomposed; plant structure distinct; yields strongly turbid water, no peat substance escapes between the fingers, residue rather mushy; (5) Moderately decomposed; plant structure evident, but becoming indistinct; yields much turbid brown water, some peat escapes between the fingers, residue very mushy; (6) strongly decomposed; plant structure somewhat indistinct, but more evident in the squeezed residue than in the undisturbed peat; about one-third of the peat escapes between the fingers, residue strongly mushy; (7) Strongly decomposed; plant structure indistinct, but recognizable; about one-half of the peat escapes between the fingers. version 5/2010 197
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Hs (from Histic and sapric) Histic organic horizon in advanced stage of decomposition. Sapric content ≥ 70% of the horizon volume; fibric component less than 30% (Figure 9). Content of rubbed fibres < 10% of soil by dry weight (soil dried at 105 °C). Von Post scale of decomposition: 8 to 107. Remarks: Sapric horizons of brook valley systems and around wells have mostly a higher mineral fraction than those in fens or bogs. Although at first sight quite similar, the horizons can differ in structure, pH, nutrient content and base saturation due to differences in water quality, vegetation and soil organisms. Note: This horizon coincides with what is classified as humic (Klinka et al., 1981, Green et al., 1993) or saprist (Delecour, 1980). The following three horizons can be seen as special cases of the Hs horizon: Hszo = Meso or macrostructured Hs horizon with a high activity of soil animals, especially earthworms. The mineral fraction is less than 50% (Figure 10). Typically present in drained semiterrestrial humus forms (both naturally and artificially drained). Activity of earthworms is high. The mineral fraction (clay, loam and/or sand) is commonly high compared to that of fibric horizons; Hsnoz = Massive Hs horizon with low activity of soil animals. Common around bogs and rain fed ponds. Humification mainly results from the activity of microorganisms, which is typical of oligotrophic environments. Complexes of humic substances are acid and relatively poor in nutrients and bases and subject to eluviation when drained. The mineral fraction is variable; Hsl = Hs horizon with a high percentage of mineral particles (clay, silt and sand). The mineral fraction is more than 50%. The mineral component may occur in the form of thin layers. The bioactivity is comparable to Hszo.
7 von Post scale: (8) very strongly decomposed; plant structure very indistinct; about two-thirds of the peat escapes between the fingers, residue almost entirely resistant remnants such as root fibres and wood; (9) Almost completely decomposed; plant structure almost unrecognizable; nearly all the peat escapes between the fingers; (10) Completely decomposed; plant structure unrecognizable; all the peat escapes between the fingers.
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2.1.2 The mineral soil layer and its master horizons and layers
2.1.2.1 The A horizon A mineral horizon formed at the surface or below an O horizon, in which all or much of the original structure of the parent material has been obliterated and characterized by one or more of the following: An accumulation of humified organic matter intimately mixed with the mineral fraction and not displaying properties characteristic of E or B horizons (see below); Properties resulting from cultivation, pasturing, or similar kinds of disturbance; A morphology that is different from the underlying B or C horizon, resulting from processes related to its surface position. If a surface horizon has properties of both A and E horizons but the dominant feature is an accumulation of humified organic matter, it is designated an A horizon. Where the climate is warm and arid, the undisturbed surface horizon may be less dark than the underlying horizon and contains only small amounts of organic matter. It has a morphology distinct from the C layer, though the mineral fraction may be unaltered or only slightly altered by weathering; such a horizon is designated A because it is at the surface. Examples of surface horizons which may have a different structure or morphology due to surface processes are Vertisols, soils in pans or playas with little vegetation, and soils in deserts. Recent alluvial, colluvial or aeolian deposits that retain fine stratification are not considered to be an A horizon unless cultivated. The different diagnostic A horizons are identified in the field observing the soil mass by the naked eye or with 5-10X magnifying hand lens, assessing the structure (Soil Survey Manual (1993) and FAO Guidelines 2006) and consistence, and measuring the acidity (pHwater). Zanella et al. (2010) distinguishes the following five diagnostic A horizons:
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maA: biomacrostructured A horizon = A aneci-endovermic General characteristic: mixed biogenic organo-mineral peds dominate Diagnostic criteria: To be identified as a biomacrostructured A horizon, a layer must have at least four of the following: structure grade, observable in place in undisturbed soil: never weak, never lack of structure; presence of peds, observable in place in undisturbed soil as well as in the palm of the hand after applying a weak-moderate pressure on a sample of soil: all sizes of peds are present, but the volume of peds larger than 4 mm is greater than the volume of all other peds or units of soil; structure (FAO and USDA) - grade: moderate or strong; size if granular shape: medium (2-5 mm) and/or coarser; size if subangular blocky shape: fine (5-10 mm) or fine (5-10 mm) and very fine (< 5 mm); living earthworms, or earthworm galleries and/or casts; earthworm galleries within underlying horizon; pH in water >5. Origin: Biological: the whole horizon is made of anecic and endogeic earthworm faeces (the limit of 4 mm is rarely reached by droppings of arthropods and epigeic earthworms); roots and fungal hyphae (visible or not) also play an important role in the formation and stability of aggregates. Living earthworms or their galleries and casts are always present within the horizon. meA: biomesotructured A horizon = A endo-epivermic General characteristic: composed of coloured organic (dark) or/and organo-mineral biogenic peds Diagnostic criteria: The biomesotructured A horizon has all the following properties: structure grade, observable in place in undisturbed soil: never weak, never lack of structure; presence of peds, observable in place in undisturbed soil as well as in the palm of the hand after applying weak pressure on a sample of soil: all sizes of peds are present, but the volume of the peds larger than 1 mm and smaller than 4 mm is greater than the volume of all the other peds or parts of soil; structure (FAO and USDA) - grade: moderate or strong (rarely weak); size if granular shape: fine (1-2 mm) and/or medium (2-5 mm); size if subangular blocky shape: very fine (<5 mm). living earthworms, arthropods or enchytraeids or their droppings. Origin: Biological: earthworms (mostly epigeic and small endogeic), enchytraeids and arthropods are responsible for the structure; roots and fungal hyphae are also involved. Anecic and large endogeic earthworm droppings, classified typically as biomacro peds, are generally larger than 4 mm.
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NB.: Green et al. (1993) described a rhizomull characterized by an A horizon which could be a biomesostructured A horizon. In this case, the thick mat of fine roots of grasses plays a major role in determining the type of structure of the topsoil.
miA: biomicrostructured A horizon = A enchy-arthropodic General characteristic: composed of fine mineral grains mixed with fine organic particles and dark-coloured biogenic peds (holorganic or hemiorganic) Diagnostic criteria: The biomicrostructured A horizon has at least five of the following properties: absence of peds > 4 mm; observable both in situ, in undisturbed soil, and in the palm of the hand after applying a slight pressure on a sample of soil: peds of varying size can be present, but the volume of peds smaller than 1 mm is greater than the volume of all other peds or parts of the soil; gently squeezing the soil, almost all large peds easily reduce into smaller units; structure (FAO and USDA) - grade: moderate, strong; shape: granular; size: very fine (< 1 mm); presence of (generally uncoated) mineral grains (mineral component > 10%); > 10% organic particles and dark-coloured biogenic peds (holorganic or hemiorganic = humic component) living arthropods, enchytraeids or their droppings; pH in water <5. Origin: Biological: the horizon has an important amount of faecal pellets, droppings of enchytraeids (potworms) (larval stages, insects, spiders, mites, springtails…), micro-arthropods and particles of organic matter (remains of decomposed litter). Hyphae and roots are also very common. Field identification: Take a sample of A horizon rich organic soil material. If squeezed gently in the palm of the hand, the sample breaks up into units composed of organic and organo-mineral peds (single or bound droppings, droppings bound to mineral grains), organic particles and mineral grains. Observing the soil with a magnifying hand lens (5-10X) reveals a lot of complex holorganic and hemorganic peds. Their mean size is less than 1 mm but the structure of the soil is clearly expressed and never weak or absent. The appearance can be very similar to that of the OH horizon. Observed on sandy or loamy substrate (acid or non calcareous). The large amount of quartz grains (> 50%) seems to prevent the formation of a larger size structure or a massive one.
sgA: single grain A horizon General characteristic: single grained structure, biological aggregation absent or involving less than 5% of the soil volume Diagnostic criteria: To be identified as a single grain A horizon, a layer must have at least four of the following: an unbound loose consistence (undisturbed soil mass); version 5/2010 201
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structure (FAO and USDA): single grain; presence of clean (= uncoated) mineral grains; <10% of fine organic particles and/or dark-coloured biogenic (holorganic or hemorganic) peds; pH in water < 5. Origin: Mineral grains coated with organic matter indicate a process of podzolisation in places. Faecal pellets of micro-arthropods or enchytraeids are sometimes present but irrelevant (< 10%). Field identification for structure and consistency: In undisturbed soil - Structure: single grain. Sub-units of soil do not appear bound together or are weakly bound in a casual manner. Sometimes, in a relatively organic sample, very small peds (< 1 mm) are detectable in the mass (animal pellets), because of their dark colour and organic composition in a light mineral mass. At other times the horizon looks like a brownish-red coloured nearly uniform fluffy mass. In this case, it is very difficult to separate mineral from scarcely present organic components. In a sample of soil in the palm of the hand - When squeezing gently with the fingers, the sample breaks up progressively into large then fine, artificial units. The fine units are mostly mineral, more or less coloured by organic matter in coatings. Animal pellets are absent or in traces (less than 10%). The sample could be wrongly classified as weak medium granular structured but grains, never zoogenic, break easily into micro units because they are very weakly attached together in variable manner and size (no apparent soil structure). Horizon designation: Because of observable processes of eluviation or podzolisation, the horizon could be classified as EA (or E) or AB following its similarity to mineral horizons.
msA: massive A horizon General characteristic: massive structure, biological aggregation absent or involving less than 5% of the soil volume Diagnostic criteria: To be identified as a massive A horizon, a layer must have at least three of the following: heterogeneous but one-piece matrix; structure (FAO and USDA): massive; presence of clean (= uncoated) mineral grains; pH in water < 5. Origin: Presence of mineral grains coloured by organic matter in coatings. Cohesion forces among parts of soil seem equally distributed in the soil, as they depend mostly on physical or chemical conditions rather than biological aggregation (peds originated by animals < 5%). Past biological activity (incorporation of organic matter) could also be involved in the process of formation of the horizon, but traces of current biological activity are never visible. Organic or hemorganic pellets of microarthropods or enchytraeids are present (< 5% of the soil volume). A 5- 10 X magnifying hand lens is necessary to detect the composition of the pellets or grains, the size of the most common biostructured units being less than 1 mm.
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Field identification for structure and consistency: In undisturbed soil - Structure: massive. The units of soil are bound together in a relatively compact manner. No planes or zones of weakness are detectable in the mass, which appears as a heterogeneous coloured layer of organo-mineral soil. If the soil is dry, when applying a moderate to strong pressure with the fingers, the soil sample progressively breaks up into finer artificial units. These fine units have a varying composition: mineral, organo-mineral and organic. If the soil is moist, the shape of the sample can be modified as in a tender, plastic, non-elastic matter. Horizon designation: Because of observable processes of eluviation or initial podzolisation, the horizon could be classified as AE (or EA), following its resemblance to a mineral E horizon.
Zoogenic and non zoogenic A horizon Azo = zoogenic A horizon. Azo = maA (implied maAzo) or meA (meAzo) or miA (miAzo). Anoz = A horizon considered as non zoogenic. To the naked eye, or with the help of a hand lens, this horizon does not show relevant (mass) signs of animal activity (absence of galleries; droppings, mucus, animal remains etc., < 5% of the soil volume). Zoological agents are not involved in the soil aggregation. Fungal structures can be visible. Anoz = sgA (implied sgAnoz) or msA (msAnoz).
2.1.2.2 E horizon: A mineral horizon in which the main feature is loss of silicate clay, iron, aluminium, or some combination of these, leaving a concentration of sand and silt particles, and in which all or much of the original structure of the parent material has been obliterated. An E horizon is usually, but not necessarily, lighter in colour than an underlying B horizon. In some soils, the colour is that of the sand and silt particles but, in many soils, coatings of iron oxides or other compounds mask the colour of the primary particles. An E horizon is most commonly differentiated from an underlying B horizon in the same soil profile by colour of higher value or lower chroma, or both; by coarser texture; or by a combination of these properties. An E horizon is commonly near the surface, below an O or A horizon and above a B horizon, but the symbol E may be used without regard to position in the profile for any horizon that meets the requirements and that has resulted from soil processes.
2.1.2.3 B horizon: A horizon formed below an A, E, H or O horizon, and in which the dominant features are the obliteration of all or much of the original structure of the parent material, together with one or a combination of the following: Illuvial concentration of clay, iron, aluminium, humus, carbonates, gypsum, silica or some combination of these; Evidence of removal of carbonates; Residual concentration of iron and aluminium oxides; Coatings of humus and/or oxides that make the horizon conspicuously lower in value, higher in chroma, or redder in hue than overlying and underlying horizons; version 5/2010 203
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Alteration that forms silicate clay or liberates oxides or both, and that forms a granular, blocky, or prismatic structure if volume changes accompany changes in moisture content; Brittle consistence. All kinds of B horizons are, or were originally, subsurface horizons. Included as B horizons are layers of illuvial concentration of carbonates, gypsum, or silica (these horizons may or may not be cemented) and brittle horizons that have other evidence of alteration, such as prismatic structure or illuvial accumulation of clay. Examples of layers that are not B horizons are layers in which clay films either coat rock fragments or are on finely stratified unconsolidated sediments, whether the films were formed in place or by illuviation; layers into which carbonates have been illuviated but that are not contiguous with an overlying pedogenetic horizon; and layers with gley colours but no other pedogenetic changes.
2.1.2.4 C horizon: A horizon, excluding hard bedrock, that is little affected by pedogenetic processes (lacks properties of H, O, A, E, or B horizon). The material of C layers may be either like or unlike that from which the soil is presumed to have formed. A C layer may have been modified even if there is no evidence of pedogenesis. Plant roots can penetrate C layers, which provide an important growing medium. Included as C layers are sediments, saprolite, and unlithified geological materials that, commonly, slake within 24 hours when air-dry chunks are placed in water and, when moist, can be dug with a spade. Some soils form in material that is already highly weathered; such material that does not meet the requirements of A, E or B horizons is designated C. Changes not considered pedogenetic are those not related to overlying horizons. Layers having accumulations of silica, carbonates, or gypsum, even if indurated, may be included in C layers, unless the layer is obviously affected by pedogenetic processes; then it is a B horizon.
2.1.2.5 R layer: Hard bedrock underlying the soil. Granite, basalt, quartzite and indurated limestone or sandstone are examples of bedrock that are designated R. Air-dry or drier bits of an R layer, when placed in water, will not slake within 24 hours and are resistant to pressure with the fingers. The R layer is sufficiently coherent when moist to make digging with a spade impractical, although it may be chipped or scraped. Some R layers can be ripped with heavy power equipment. The bedrock may be fissured, but few roots can penetrate. The cracks may be coated or filled with clay or other material.
2.1.2.6 I layer: Ice lenses and wedges that contain at least 75% ice (by volume) and that distinctly separate organic or mineral layers in the soil. In areas affected by permafrost, ice bodies may form lenses of wedges that separate entire soil layers. Where such ice concentrations occur within the depth of soil description, they can be designated as I layer.
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2.2 Transitional horizons
There are two kinds of transitional horizons: those with properties of two horizons superimposed and those with the two properties separate. For horizons dominated by properties of one master horizon but having subordinate properties of another, two capital letter symbols are used, such as AB, EB, BE and BC. The master horizon symbol that is given first designates the dominant properties: an AB horizon, for example, has characteristics of both an overlying A horizon and an underlying B horizon, but is more like the A than like the B. In some cases, a horizon can be designated as transitional even if one of the master horizons to which it is apparently transitional is not present. A BE horizon may be recognized in a truncated soil if its properties are similar to those of a BE horizon in a soil in which the overlying E horizon has not been removed. An AB or a BA horizon may be recognized where bedrock underlies the transitional horizon. A BC horizon may be recognized even if no underlying C horizon is present; it is transitional to assumed parent material. A CR horizon can be used for weathered bedrock which can be dug with a spade though roots cannot penetrate except along fracture planes. Horizons or layers in which distinct parts have recognizable properties of two kinds of master horizons are indicated as above, but the two capital letters are separated by a stroke (/), as E/B, B/E, B/C or C/R. Commonly, most of the individual parts of one component are surrounded by the other material.
2.3 Subordinate characteristics within master horizons and layers
Designations of subordinate distinctions and features within the master horizons and layers are based on characteristics observable in the field. Lower case letters are used as suffixes to designate specific kinds of master horizons and layers, and other features. The list of symbols and terms is explained more in detail below:
Suffix Description Use for a Evidence of cryoturbation: Irregular or broken boundaries, sorted rock No restriction fragments (patterned ground), or organic matter in the lower boundary between the active layer and permafrost layer. b Buried horizon: Used in mineral soils to indicate identifiable buried Mineral horizon, horizons with characteristics that were formed before burial. Horizons not cryoturbated may or may not have developed in the overlying materials which may be either like, or unlike, the assumed parent material of the buried soil. The symbol is not used in organic soils or to separate an organic layer from a mineral layer, in cryoturbated soils, or with C layers. c Concretions or nodules: In mineral soil it indicates a significant Mineral horizon accumulation of concretions or of nodules. The nature and consistence of the nodules is specified by other suffixes and in the horizon description. d Dense layer: Used in mineral soils to indicate a layer of relatively Mineral horizon unaltered, mostly earthy material that is not cemented but that has such bulk density or internal organization that roots cannot enter except in cracks; the symbol is not used in combination with the symbols m (cementation) and x (fragipan). f Frozen soil: Designates a horizon or layer that contains permanent ice Not in I and R or is perennially colder than 0°C. It is not used for seasonally frozen horizons layers or for bedrock (R). Dry frozen soil layers may be labelled (f). g Stagnic conditions: Designates a horizon with a distinct pattern of No restriction mottling that reflects alternating conditions of oxidation and reduction of sesquioxides, caused by seasonal surface waterlogging. If aggregates version 5/2010 205
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are present, the interiors of the aggregates show oxidising colours and the surface parts reducing colours. h Accumulation of organic matter: Designates the accumulation of Mineral horizon organic matter in a mineral horizon. The accumulation may occur in a surface horizon or in subsurface horizons (through illuviation). i Slickensides: In mineral soils, denotes the occurrence of slickensides, No restriction i.e. oblique shear faces caused by the shrink-swell action of clay; wedge-shaped polished peds and seasonal surface cracks are commonly present. j Jarosite: Indicates the presence of jarosite (straw-yellow) mottles, No restriction coatings or hypodermic coatings. k Accumulation of pedogenetic carbonates: Indicates an accumulation of No restriction alkaline earth carbonates, commonly calcium carbonate. l Capillary fringe mottling: Indicates mottling caused by ascending No restriction groundwater. If aggregates are present, the interiors of the aggregates show reducing colours and the surface parts oxidising colours. m Strong cementation or induration: In mineral soils, indicates continuous Mineral horizons or nearly continuous cementation - used only for horizons that are more than 90 % cemented, though they may be fractured. The layer restricts rooting to fracture planes. The single predominant or co-dominant cementing agent may be indicated using defined letter suffixes single or in pairs. If the horizon is cemented by carbonates km is used; by silica, qm; by iron, sm; by gypsum, ym; by both lime and silica, kqm; by salts more soluble than gypsum, zm. n Pedogenetic accumulation of exchangeable sodium. No restriction o Residual accumulation of iron/aluminium oxides: Indicates residual No restriction accumulation of sesquioxides, as opposed to the symbol s, which indicates illuvial accumulation of oxides or organic and oxide mixture. p Ploughing or other artificial disturbance: Indicates mixing of the surface No restriction; E, layer by ploughing or other tillage practices. A disturbed organic B or C as Ap horizon is designated Op or Hp. A disturbed mineral horizon, even though clearly originally an E, B or C, is designated Ap. q Accumulation of pedogenetic silica: If silica cements the layer and No restriction cementation is continuous or nearly continuous, qm is used. r Strong reduction: Indicates presence of iron in reduced state. If r is No restriction used with B, pedogenetic change in addition to reduction is implied; if no other change has taken place, the horizon is designated Cr. s Illuvial accumulation of iron/aluminium oxides: Used with B to indicate B horizon the accumulation of illuvial, amorphous, dispersible organic matter- oxide complexes if the value and chroma of the horizon are more than 3. The symbol is also used in combination with h as Bhs if both the organic matter and oxide components are significant and both value and chroma are approximately 3 or less. t Accumulation of clay: Used with B or C to indicate an accumulation of B and C horizon clay that either has formed in the horizon or has been moved into it by illuviation, or both. At least some part should show evidence of clay accumulation in the form of coatings on ped surfaces or in pores, as lamellae, or as bridges between mineral grains. u Urban and other man-made materials: Used to indicate the dominant H, O, A, E, B and presence of man-made C horizons materials. v Plinthite: Indicates the presence of iron-rich, humus-poor material that No restriction is firm or very firm when moist and that hardens irreversibly when exposed to the atmosphere. When hardened, it is no longer called plinthite but a hardpan, ironstone, a petroferric or a skeletic phase – in which case v is used in combination with m. w Development of colour or structure in B: Indicates development of B horizons colour or structure, or both, in B horizons lacking other diagnostic 206 www.icp-forests.org/Manual.htm
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characteristics. It is not used to indicate a transitional horizon. x Fragipan: Brittle consistency or high bulk density attributed to No restriction pedogenetic processes. y Pedogenetic accumulation of gypsum. No restriction z Pedogenetic accumulation of salts more soluble than gypsum. No restriction
Conventions for using letter suffixes Many master horizons and layers that are symbolized by a single capital letter will have one or more lowercase letter suffixes. More than three suffixes is cumbersome. The following rules apply: Letter suffixes should immediately follow the capital letter; A B horizon that has significant accumulation of clay and also shows evidence of development of colour or structure, or both, is designated Bt (t has precedence over w, s and h); Suffixes are listed alphabetically.
2.4 Vertical subdivisions
A horizon or layer designated by a single combination of letter symbols can be subdivided using arabic numerals following the letters. Within a C, for example, successive layers could be C1, C2, C3, etc.; or if the lower part is gleyed and the upper part is not, the designations could be C1-C2- Cg1-Cg2 or C-Cg1-Cg2-R. These conventions apply whatever the purpose of subdivision. A horizon identified by a single set of letter symbols may be subdivided on the basis of morphology, such as structure, colour, or texture. These subdivisions are numbered consecutively. The numbering restarts with 1 at whatever level in the profile. Thus Bt1-Bt2-Btk1-Btk2 is used, not Bt1-Bt2-Btk3-Btk4. The numbering of vertical subdivisions within a horizon is not interrupted at a discontinuity (indicated by a numerical prefix) if the same letter combination is used in both materials: Bs1-Bs2- 2Bs3-2Bs4 is used, not Bs1-Bs2-2Bs1-2Bs2. A and E horizons can be subdivided similarly, for example Ap1, A1, A2, Ap2, A3; and E1, E2, Eg1, Eg2.
2.5 Discontinuities
In mineral soils, arabic numerals are used as prefixes to indicate discontinuities. Wherever needed, they are used preceding A, E, B, C and R. They are not used with I, although this symbol clearly indicate a discontinuity. These prefixes are distinct from arabic numerals used as suffixes to denote vertical subdivisions. A discontinuity is a significant change in particle size distribution or mineralogy that indicates a difference in the material from which the horizons formed or a significant difference in age, or both -unless that difference in age is indicated by the suffix b. Symbols to identify discontinuities are used only when they will contribute substantially to the reader’s understanding of relationships among horizons. The stratification common in soils formed in alluvium is not designated as discontinuities - unless particle size distribution differs markedly from layer to layer - even though genetic horizons have formed in the contrasting layers. Where a soil has formed entirely in one kind of material, no prefix is used (the whole profile is material 1). Similarly, the uppermost material in a profile having two or more contrasting materials is understood to be material 1, but the number is omitted. Numbering starts with the second layer of contrasting material, which is designated 2. Underlying contrasting layers are version 5/2010 207
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numbered consecutively. Even though a layer below material 2 is similar to material 1, it is designated 3 in the sequence. The numbers indicate a change in the material, not the type of material. Where two or more consecutive horizons formed in one kind of material, the same prefix number applies to all of the horizon designations in that material, e.g. Ap-E-Bt1-2Bt2-2Bt3-2BC. The number suffixes designating subdivisions of the Bt horizon continue in consecutive order across the discontinuity. If an R layer is below a soil that formed in residuum and the material of the R layer is judged to be like that from which the material of the soil weathered, the arabic number prefix is not used. If the R layer would not produce material like that in the solum, the number prefix is used, as in A-Bt-C- 2R or A-Bt-2R. If part of the solum formed in residuum, R is given the appropriate prefix: Ap-Bt1- 2Bt2-2Bt3-2C1-2C2-2R. In organic soils, discontinuities between different kinds of layers are not identified. In most cases the differences are shown by the letter suffix designations, if the different layers are organic, or by the master symbol if the different layers are mineral.
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FutMon Field Protocol Determination of the soil water retention characteristic V 1.0; last update 15th May 2009
Soil water retention characteristic (pF analysis) Method sheet SA14 Reference method ISO 11274 Method suitable for Mineral and organic soil horizons, undisturbed samples
1. Introduction
During the FutMon LIFE+ project 2009-2010, the demonstration action D3 aims at the assessment of forest water budgets. Data is collected on more than 100 D3 plots being a subset of the IM1 plots. For the parameterisation of various water balance models meteo data, stand characteristics and soil physical data are essential. For the validation of the models soil temperature, soil moisture and stand precipitation measurements are needed.
The soil water retention characteristic is a physical soil property depending mainly on soil texture, organic material and bulk density. Therefore it will vary both vertically (horizons/layers in the profile) and horizontally in each plot. Stratified sampling according to horizons or specific layers is a prerequisite to determine the overall hydrological behaviour of a soil profile.
Specific points on the soil water retention curve (SWRC), which is the relationship between volumetric soil water content and matric pressure, are required to (1) determine indices of the volume of plant-available water, (2) estimate the soils’ pore size distribution and (3) predict other soil physical properties (e.g. hydraulic conductivity). The SWRC is an essential part in most water budget models.
This protocol describes the determination of the soil water retention characteristic in the laboratory, extending from saturated soil (no pressure or suction; 0 kPa) to oven-dry soil (about -106 kPa).
The format of this protocol is in line with the new standard structure for sub-manuals proposed by the QA committee (Quality objectives in FutMon).
2. Scope and application
This FutMon protocol conforms the ISO 11274 international standard for determination of the soil water retention characteristic based on measurements of the drying or desorption curve. All methods described by ISO 11274 are allowed, except method B, using a porous plate and burette apparatus for matric pressures from 0 to -20 kPa.
The volumetric soil water content at matric pressure 0 kPa is approximated by the total porosity of the soil.
In addition this protocol describes the mandatory and optional matric pressures to assess in the lab as adopted for FutMon action D3. This further standardisation is a prerequisite for facilitation and harmonisation of database handling.
The protocol outlines the general description of basic sampling and laboratory operation for soil water retention analysis at plot level. Definitions of variables and guidelines for method selection and sampling are applied as described in the ISO 11274:1998 method (ISO, 1998).
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3. Operational objectives
The general operational objectives are:
• To determine on each plot the SWRC for specific soil layers of at least 3 profiles. The field matric potential for each layer will be inferred from the measured water content (WC) and its layer specific SWRC;
• To assess the SWRC at plot level only once. Just like texture, the SWRC is considered a constant soil property showing little change over time;
• To harmonise and standardize the field methods for sampling undisturbed soil samples and the determination of the SWRC in the lab;
• To quantify the accuracy (trueness and precision) of the results of SWRC determination, based on within lab analysis of replicate samples (e.g. twin field samples) and participation in interlaboratory physical soil comparisons using reference material;
• To assess the spatial variation of the SWRC within the plot;
• To use the SWRC for the parameterization of various water budget models (e.g. WATBAL, BROOK90, SIMPLE, COUP, THESEUS, WASIM-ETH, …). The prediction capacity of these models will be partly determined by the uncertainty of parameters derived from the SWRC.
The specific operational objectives described in this protocol are:
• adequate sampling of undisturbed soil in situ;
• correct handling of undisturbed soil cores prior to analysis;
• analysis of the soil water characteristic in the laboratory;
• standardised reporting of the SWR results.
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4. Location of measurements and sampling
4.1 Sampling design at plot level
4.1.1. Sampling locations (profiles) within the plot
On each plot at least 3 profiles are sampled separately. The location of these profiles within the plot may be chosen freely, as long as their spatial design meets following requirements:
• the individual profiles are representative for the soil condition within the plot;
• the profiles are not located in one single profile pit (i.e. profiles are at least some meters apart);
• the profiles should be situated as close as possible to the location of the soil moisture measurement sensors;
The exact coordinates of each profile location should be determined.
4.1.2. Sampling within the soil profile
At each location, adequate undisturbed soil sampling within the soil profile is done according to the sampling scheme in Table 1. At least one undisturbed core is taken within the fixed depth intervals 0 - 20, 20 - 40 and 40 - 80 cm, preferentially at the same depth as the soil moisture measurements (depth of TDR sensors). The exact depth range of the soil core (top to bottom of core) is reported, along with the ring ID information.
When forest floor thickness (OF + OH layer) is > 5 cm, the holorganic layer should be sampled also with a suitable cylinder. Optionally, extra soil layers or horizons could be sampled that are considered relevant for the hydrological regime of the soil profile.
Table 1. Soil profile sampling scheme
Matrix Depth interval (cm) Minimum number of Requirements for replicates D3 per profile per plot Organic Layer Forest floor > 5 cm thick 1 3 Mandatory Forest floor <= 5 cm thick - - not required Mineral layer 0 - 20 cm 1* 3 Mandatory 20 - 40 cm 1* 3 Mandatory 40 - 80 cm 1* 3 Mandatory > 80 cm - - Optional Extra (specific) layer - - Optional (*) if the mineral layer is difficult to sample (e.g. caused by higher gravel content) a higher number of samples are strongly recommended).
Concluding from Table 1, on each plot at least 9 undisturbed and representative samples should be taken if the forest floor is less than 5 cm thick and 12 samples if the forest floor is more than 5 cm thick.
For each undisturbed sample, the pedogenetic horizon according to FAO (2006) designations, should be reported that contains the centre of the sampling cylinder. The pedogenetic horizon may be deduced from the soil profile description of the sampled plot.
Hence for each undisturbed core sample following information is reported:
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• exact depth range of core cylinder in cm (e.g. 10 -15 cm for a cylinder of 5 cm in height);
• pedogenetic horizon containing centre of undisturbed sample (e.g. 12.5 cm is located in E horizon)
4.2. Sampling equipments
4.2.1. Sampling cylinders
Undisturbed soil cores are taken in dedicated metal cylinders (sleeves) with a volume between 100 and 400 cm³. Plastic cylinders are dissuaded. The same steel cylinders can be used as for determination of bulk density (method SA04). The sample ring dimensions should be representative of the natural soil variability and structure.
Recommended dimensions (height x diameter in mm) of cylinders for forest soil sampling are: 50 x 53, 40 x 76 and 50 x 100. It is important to verify that the laboratory that will process the undisturbed samples is equipped for the type of sample rings used.
The bottom of the sample ring should have a cutting edge. Plastic lids should perfectly fit to both ends of the steel cylinder.
4.2.2. Sampling material
In a soil profile pit, undisturbed samples can be taken directly using the sample ring, without extra material like an open or closed ring holder. In that case, after introduction, the soil sample ring should be dug out carefully.
Alternatively, an open ring holder may be used. In such a holder, the ring is locked by means of a rubber or lever. Over the ring some space headroom is left allowing for taking an oversize sample. This prevents the sample for compaction during sampling. In hard soil layers, an impact absorbing hammer may be used for hammering the ring holder into the soil.
When sampling is done in a bore-hole, a closed ring holder is recommended. This type of ring holder holds the cylinder in a cutting shoe. The ring is clamped inside the cutting shoe and no water or soil can come into the ring from the top. Moreover, the sample ring is protected, the sample is oversized on both sides and there is no risk of losing or damaging the sample ring. In hard layers, an impact absorbing hammer may be used with care.
Trimming both ends of the cylinder is preferably done using a small frame saw. A spatula or knife may be used but care has to taken avoid smearing the surface (closing macro- and mesopores).
After closing the cylinders with plastic lids, the sample should be labeled and wrapped in plastic bags or plastic or aluminium foil to prevent drying.
In conclusion, the sample material is: • steel cylinders (sample rings) with lids • open ring holder (optional) • closed ring holder (needed when sampling in boreholes) • spade and/or trowel for digging out the cylinder • impact absorbing hammer (for hard soil layers only) • small frame saw • spatula or knife
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• waterproof marker for labeling • plastic bags or foil for wrapping the ring
4.3. Sample collection
Undisturbed samples should be collected during a wet period, preferentially when soil matric pressures are at or near field capacity. Do not sample the soils when it is freezing.
The sampling procedure for undisturbed soil sampling (core sampling in steel rings) is as follows:
• Take soil cores carefully to ensure minimal compaction and disturbance to the soil structure, either by hand pressure in suitable material or by using a suitable soil corer and/or core holder. Take one sample (preferentially 3) for each freshly exposed soil horizon or layer; more replicates are required in stoney soils;
• The ring sample is taken vertically with its cutting edge downwards;
• Dig out the cylinder carefully with a trowel, if necessary adjust the sample within the cylinder before trimming flush, trim roughly the two faces of the cylinder with a small frame saw or a knife and fit lids to each end;
• Record the sampling date, sample grid reference, horizon encompassing the centre of the core, and the exact sampling depths (depth of top and bottom of the cylinder with respect to the top of the mineral horizon).
• Label the cylinder on the lid clearly with the sample plot reference, the sampling date, the horizon code and the sample depth;
• Wrap the ring samples in plastic bags or a plastic or aluminium foil to prevent drying;
4.4. Sample storage and transport
The undisturbed samples are transported in plastic boxes or aluminium cases. They protect the samples from heat, humidity or dust. If transported in vehicles over long distances, shocking of samples should be avoided by using shockproof materials.
Prevent undisturbed soil samples from freezing. Store the samples at 1 to 2 °C to reduce water loss and to suppress biological activity until analysis. Samples with obvious macrofaunal activity should be treated with a suitable biocide, e.g. 0,05 % copper sulfate solution.
It is recommended to avoid weeks of storage of undisturbed soil samples. Ideally, undisturbed soil samples are analyzed in the lab immediately after sampling.
5. Measurements
5.1 Measurements to be done and reporting units.
In order to determine the SWRC, the volumetric water content (θ in volume fraction, m3 m-3) is determined at predefined matric potentials (ψ, in kPa). As indicated in Table 2, six of these matric heads are mandatory to determine. Extra observations of the SWRC at pressures -10, - 100 and -250 kPa are optional but they greatly improve fitting the SWRC.
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Some matric heads immediately provide information on SWRC parameters: at 0 kPa the maximum water holding capacity (WHC) of the saturated soil sample is determined; depending on definitions and soil texture field capacity (FC) may be inferred from -5 till -100 kPa; permanent wilting point (PWP) is attained at a matric pressure of – 1500 kPa and dry bulk density (lowest pressure at about 10-6 kPa) derived in the oven at 105°C. The standard instruments required for each determination are listed in Table 2.
Table 2. Overview of matric heads to assess for the determination of the SWRC. Mandatory pressures to determine are in bold, optional in italic.
Matric potential ψ Recommended Instrument Estimator pF kPa 0.0 0 Pycnometer ≈θsat=WHC= Total porosity 1.0 -1 Sand suction table 1.7 -5 Sand suction table FC 2.0 -10 Sand suction table FC sand 2.5 -33 Kaolin suction table FC siltloam 3.0 -100 Kaolin suction table FC clay 3.4 -250 Ceramic plates 4.2 -1500 Ceramic plates PWP 7.0 -106 Oven Dry BD
Where: 1) the pF is the logarithm of the absolute value of the matric potential expressed by the graduation of the water column (cm). 2) 1 kPa = 10.22 cm H2O or 1 cm H2O column = 0.097885 kPa 3) 100 kPa = 1 bar
5.1.1. Determination of the soil water characteristic
The ISO 11274:1998 allows 4 methods to determine matric pressures within specific ranges:
A) method using sand, kaolin or ceramic suction tables for determination of matric pressures from 0 kPa to - 50 kPa; B) method using a porous plate and burette apparatus for determination of matric pressures from 0 kPa to - 20 kPa; (single sample) C) method using a pressurized gas and a pressure plate extractor for determination of matric pressures from - 5 kPa to - 1500 kPa; D) method using a pressurized gas and pressure membrane cells for determination of matric pressures from - 33 kPa to - 1500 kPa.
Since method B allows only processing a single sample at the time, use of this method is not recommended. Laboratories are free to apply methods A, C and D according to the ISO 11274 standard. Guidelines for choosing the most appropriate method for specific soil types are given in ISO 11274, chapter 3.
Before applying methods A, C or D, general recommendations for sample preparation are:
• For measurements at pressures from 0 to -50 kPa, use a nylon mesh to retain the soil sample in the sleeve and secure it with an elastic band or tape;
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• Ensure maximum contact between the soil core, mesh and the porous contact medium of the suction tables, plates or membranes; remove any small projecting stones if necessary;
• Avoid smearing the surface of (clayey) soils, especially when water saturated;
• Inspect the sample for bioturbation (worms, isopods) or germination of seeds during analysis; the use of a biocide is discouraged;
• Report the temperature at which the water-retention measurements are made;
• Ideally, measurements start with field-moist samples [i.e. do not dry the undisturbed samples first (hysteresis effect)]. Then, samples are saturated with water.
• Respect wetting times before starting measurements to obtain a saturated sample. General guidelines for wetting times according to ISO 11274 are: – sand 1 to 5 days – loam 5 to 10 days – clay 5 to 14 days or longer – peat 5 to 20 days.
5.1.2. Method A (recommended method for matric pressures 0, -1, -5, -10 and -33 kPa)
Determination of the soil water characteristic using sand, kaolin and ceramic suction tables
Apparatus
• Suction table (watertight, rigid container with outlet in base and close fitting cover) • Drainage system for suction table, enabling to maintain suction at specific matric pressures • Sand, silt or kaolin packing material, appropriate for use in suction tables (homogenous, sieved, graded and washed, free of organic material or salts). Material should achieve the required air entry values (see ISO 11274 for details) • Drying oven capable of maintaining temperature of 105 ± 2 °C • Balance (accuracy 0.1% of measured value)
Procedure • Weigh the cores and then place them on a suction table at the desired matric pressure with table cover closed. The reference 0 cm height for setting the suction level is the middle of the core; • Leave the cores for 7 days (minimum equilibration time). Equilibrium is reached if daily change in mass of the core is less than 0,02 %; • If equilibrium is reached, weigh the cores, if not, replace cores firmly onto the suction table and wait until equilibrium is reached.
Calculation
ISO 11274 describes two procedures:
1. Procedure for soils containing less than 20 % coarse material (diameter greater than 2 mm) 2. Procedure for stony soils; conversion of results to a fine earth basis
For soils with less than 20% coarse material:
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• Calculate the water content mass ratio at matric pressure ψi using the formula:
WCψi = (Mψi – Mdry) / Mdry
where WCψi is the water content mass ratio at a matric pressure ψi, in grams; Mψi is the mass of the soil sample at matric pressure ψi, in grams; Mdry is the mass of the oven-dried soil sample, in grams.
• Calculate the volumetric water content at matric pressure ψi using the formula:
-3 θψi = [(Mψi – Mdry) / (V x ρw) ] x 10
alternatively
θψi = WCψi x (ρb / ρw)
where 3 -3 θψi is the water content volume fraction at matric pressure ψi, expressed in m m (volume of water per volume of soil); Mψi is the mass of the soil sample at matric pressure ψi, in grams; Mdry is the mass of oven dried soil sample, in grams; V is the volume of the soil sample in m³ - ρw is the density of water, in kg m ³ - ρb is the bulk density of oven dried soil at 105°C, in kg m ³.
For soils with more than 20% coarse material, data needs conversion to a fine earth basis as follows:
The volumetric water content of the fine earth (θf) equals:
θf = θt / (1- θs)
where: θf water content of the fine earth, expressed as a volume fraction (m3 m-3);
θs volume of non-porous stones, expressed as a fraction of total core volume (m3 m-3);
θt is the water content of the total earth, expressed as a fraction of total core volume (m3 m-3);
For porous stones, a different correction should be applied as described in ISO 11274.
If volumetric water content is reported on fine earth basis, this should be clearly reported along with the volume of non-porous stones in the sample.
5.1.3. Method C (recommended method for matric pressures -250 and -1500 kPa)
Determination of soil water characteristic by pressure plate extractor
Apparatus
• Pressure plate extractor with porous ceramic plate • Sample retaining rings/soil cores with discs and/or lids
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• Air compressor (1700-2000 kPa), nitrogen cylinder or other pressurized gas) • Pressure regulator and test gauge • Drying oven capable of maintaining temperature of 105 ± 2 °C • Balance (accuracy 0.1% of measured value)
Follow the manufacturer’s instruction to assemble and operate the apparatus.
Procedure
• Take small subsamples from the undisturbed sample: soil cores of approximately 5 cm diameter and between 5 mm and 10 mm in height; smaller samples for lower pressures are used in order to avoid long equilibration times; • It is acceptable to use disturbed samples at pressures lower than - 100 kPa, providing that the disturbance consists only in breaking off small pieces of soil and not in compressing or remoulding the soil. • Use at least three replicate samples of each sample and place them on a presaturated plate; • Wet the samples by immersing the plate and the samples until a thin film of water can be seen on the surface of the samples; • Create a saturated atmosphere in the extractor; • Apply the desired gas pressure and keep to a constant level, check for leaks; • Record on a daily basis the evacuated water from the samples, when no change are observed (volume in a burette remains static) the samples have come to an equilibrium; • At equilibrium status, soil samples are weighed, oven-dried and reweighed to determine the water content at the predetermined pressures
Calculation
The same calculation procedure as in 5.1.2 is applied, for samples without or with coarse fragments.
5.1.4. Method D (recommended method for matric pressures -250 and -1500 kPa)
Determination of soil water characteristic using pressure membrane cells
Apparatus
• Pressure cells with porous baseplates • Cellulose acetate membrane • Pressure regulator • Air compressor (1700-2000 kPa, nitrogen cylinder or other pressurized gas) • Drying oven capable of maintaining temperature of 105 ± 2 °C • Balance (accuracy 0.1% of measured value)
Follow the manufacturer’s instruction to assemble and operate the apparatus.
Procedure
• Soil subsamples are placed on a porous cellulose acetate membrane • Equilibrium status is attained when water outflow from the pressure cell ceases and soil water content is determined by weighing, oven-drying and reweighing the sample. • Gas pressure methods are only suited to determine matric pressures below - 33 kPa
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Calculation
The same calculation procedure as in 5.1.2 is applied, for samples without or with coarse fragments
5.1.5 Determination of the total porosity
A value for porosity can be calculated from the bulk density ρbulk and particle density ρparticle:
Often the particle density or true density of soil is approximated by 2650 kg.m-³ (mineral density of quartz). But the direct measurement of the particle density is strongly recommended to be done by the means of a pycnometer.
5.1.6. Determination of dry bulk density
Determination of dry bulk density is also done according to method SA04 (submanual IIIa) The dry bulk density (BD) is recorded in kg m-3 with no decimal places.
In the case of stony or gravely soils the bulk density of the fine earth fraction (< 2 mm) should be reported. Furthermore, the bulk density of the coarse fragments should be known, but this may be approximated as 2650 kg.m-3.
5.1.7. Reported data, their units and numerical precision
Based on the SWRC measurement in the lab, data reported for each undisturbed soil sample are listed in Table 3.
Table 3. Raw SWRC data: measurement, unit and numerical precision to be reported for each sample. Data in bold are mandatory to report.
Matric pressure Volumetric water content unit Numerical (kPa) (VWC) = θ Precision ψ 0 0.xxxx m3 m-3 0.0001
-1 0.xxxx m3 m-3 0.0001
-5 0.xxxx m3 m-3 0.0001
-10 0.xxxx m3 m-3 0.0001
-33 0.xxxx m3 m-3 0.0001
-100 0.xxxx m3 m-3 0.0001
-250 0.xxxx m3 m-3 0.0001
-1500 0.xxxx m3 m-3 0.0001
Matric pressure Dry bulk density (BD) unit Numerical (kPa) Precision ψ -106 xxxx kg m-3 0
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5.2. Data Quality Requirements
Plausibility limits for SWRC of mineral forest soils and organic layers will be developed in the future; partly based on the results of Action D3 in FutMon.
Tolerable limits for laboratory performance will be derived from the reproducibility data gained by performing the interlaboratory physical soil ringtest during FutMon.
Soil water retention data are considered complete if volumetric water content for all six mandatory matric heads (bold in Table 3) is determined. For scientific reasons analysing the optional matric heads also is strongly recommended.
Interpolation of volumetric water content between matric pressures is not allowed. All reported values should have been measured according to the methods described in this protocol.
6. Data handling
6.1. Data submission forms
Forms for storing the SWRC data in the FutMon databases will be developed under FutMon. Basically following data should be stored:
• the undisturbed sample metadata: o sample ID o plot ID o profile ID o fixed depth layer o horizon designation o sample ring depth (top) in cm below top of mineral soil o sample ring depth (bottom) in cm To be submitted with form .SWC
• the raw volumetric water content (θ = VWC in m3 m-3) data mentioned in Table 3: o VWC0 o VWC-1 o VWC-5 o VWC-10 o VWC-33 o VWC-100 o VWC-250 o VWC-1500 These values and volumetric water content with respective matric pressures be submitted with form .SWA.
• derived data from SWRC o bulk density (kg m-3; to be submitted with .SWC) o moisture content at field capacity (m3 m-3) o moisture content at permanent wilting point (m3 m-3) o Van Genuchten model parameters θr, θs, α, n o Predicted Ksat (cm day-1)
• Data quality indicators (specific file for submission of laboratory QA information, XX2009SW.LQA, still to be defined) o Lab ID (laboratory that analysed SWRC) o Lab quality indices (to be defined)
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6.2. Data processing guidelines
Soil water retention curve models will be fitted to the raw data (Table 3). For forest soils, one of the best performing functions is the Van Genuchten equation defined by its empirical parameters θr, θs and empirical constants α, n and m = 1-1/n.
Calculation of these parameters can be done using the public domain RETC programme which may be downloaded from: http://www.pc-progress.cz/Pg_RetC.htm. This software enables to predict Ksat from the SWRC measurements.
The Van Genuchten model parameters are also stored in the FutMon soil physical databases.
6.3. Reporting guidelines
Data will be reported as foreseen in the data submission forms .SWC and .SWA.
7. References
ISO 11274:1998(E). Soil Quality – Determination of the water-retention characteristic – Laboratory methods. International Organization for Standardization. Geneva, Switzerland. 20 p. (available at www.iso.ch)
705 translated and adapted after AG Boden (2005): Bodenkundliche Kartieranleitung. Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover
Particle size fraction (mass %) ksat (cm/d) Clay Silt Sand when bd < 1400 when bd between when bd > 1600 kg/m 3 1400 and 1600 kg/m3 kg/m3 65 - 100 0 - 35 0 - 35 4 3 2 45 - 65 30 - 55 0 - 25 8 3 2 45 - 65 15 - 30 5 - 40 8 6 2 45 - 65 0 - 15 20 - 55 8 5 3 35 - 45 50 - 65 0 - 20 18 9 3 35 - 45 30 - 50 5 - 35 20 7 3 35 - 45 15 - 30 25 - 60 31 10 7 35 - 45 0 - 15 40 - 65 15 11 8 25 - 35 65 - 75 0 - 10 33 12 3 30 - 35 50 - 65 0 - 20 18 9 3 25 - 35 30 - 50 15 - 45 33 13 6 25 - 35 15 - 30 25 - 60 31 10 7 25 - 35 0 - 15 50 - 75 51 38 8 17 - 30 50 - 65 5 - 33 45 16 6 17 - 25 65 - 83 0 - 18 45 13 3 17 - 25 40 - 50 25 - 43 53 23 10 17 - 25 30 - 40 35 - 53 74 23 11 17 - 25 15 - 30 45 - 68 68 36 11 17 - 25 0 - 15 60 - 83 114 42 24 12 - 17 65 - 88 0 - 23 41 12 3 12 - 17 50 - 65 18 - 42 49 20 7 12 - 17 40 - 50 33 - 52 60 28 13 12 - 17 10 - 40 43 - 78 106 42 21 12 - 17 0 – 10 73 - 95 179 118 68 8 - 12 65 - 92 0 - 27 32 12 2 8 - 12 50 - 65 18 - 42 49 20 7 8 - 12 40 - 50 33 - 52 60 28 13 8 - 12 10 - 40 48 - 82 98 65 29 5 - 12 0 – 10 73 - 95 179 118 68 0 - 8 80 - 100 0 - 20 32 13 2 0 - 8 50 - 80 12 – 50 37 22 5 0 - 8 40 - 50 42 - 60 58 38 17 0 - 8 25 - 40 52 - 75 88 59 31 5 - 8 10 - 25 67 - 85 161 98 52 0 - 5 10 - 25 70 - 90 174 127 66 0 - 5 0 - 10 85 - 100 375 340 230 Soil textures sorted after maximum clay content (1st instance) and maximum silt content (2nd instance) bd: measured bulk_density of the fine earth [kg/m³]
706 Food and Agriculture Organization of the United Nations (2006) Jahn, R, Blume, H-P, Asio, VB, Spaargaren, O, Schad, P, Langohr, R, Brinkman, R, Nachtergaele, FO, Krasilnikov, RP. Guidelines for Soil Description and Classification, 4th edition. ftp://ftp.fao.org/agl/agll/docs/guidel_soil_descr.pdf reproduced with permission
707 iii
Contents
Acknowledgements ix List of acronyms x 1. Introduction 1
2. General site information, registration and location 5 Profile number 5 Soil profile description status 5 Date of description 5 Authors 5 Location 6 Elevation 6 Map sheet number and grid reference (coordinates) 7
3. Soil formation factors 9 Atmospheric climate and weather conditions 9 Soil climate 9 Landform and topography (relief) 10 Major landform 10 Position 10 Slope form 12 Slope gradient and orientation 12 Land use and vegetation 13 Land use 13 Crops 13 Human influence 13 Vegetation 16 Parent material 16 Age of the land surface 17
4. Soil description 21 Surface characteristics 21 Rock outcrops 21 Coarse surface fragments 21 Erosion 22 Surface sealing 23 Surface cracks 23
708 iv
Horizon boundary 24 Depth 24 Distinctness and topography 25 Primary constituents 25 Texture of the fine earth fraction 25 Rock fragments and artefacts 29 Degree of decomposition and humification of peat 32 Aeromorphic organic layers on forest floors 32 Soil colour (matrix) 33 Mottling 35 Colour of mottles 35 Abundance of mottles 35 Size of mottles 35 Contrast of mottles 36 Boundary of mottles 36 Soil redox potential and reducing conditions 36 Determination of redox potential by field method 36 Reducing conditions 37 Carbonates 38 Content 38 Forms 38 Gypsum 39 Content of gypsum 39 Forms of secondary gypsum 39 Readily soluble salts 40 Procedure 40 Field soil pH 41 Soil odour 42 Andic characteristics and volcanic glasses 42 Procedure 42 Organic matter content 43 Organization of soil constituents 44 Soil structure 44 Consistence 48 Soil-water status 50 Bulk density 50 Voids (porosity) 52 Porosity 52 Type 52 Size 53 Abundance 53
709 v
Concentrations 53 Coatings 54 Cementation and compaction 56 Mineral concentrations 58 Biological activity 59 Roots 59 Other biological features 60 Human-made materials 60 Artefacts 60 Human-transported material (HTM) 61 Geomembranes and technic hard rock 62 Description of artefacts 63 Description and determination of human-transported material 64 Sampling 64
5. Genetic and systematic interpretation – soil classification 67 Soil horizon designation 67 Master horizons and layers 67 Transitional horizons 71 Subordinate characteristics within master horizons and layers 71 Conventions for using letter suffixes 75 Vertical subdivisions 75 Discontinuities 76 Use of the prime 77 Principles of classification according to the WRB 77 Step 1 79 Step 2 79 Step 3 79 Step 4 79 Principles and use of the qualifiers in the WRB 80 Checklist of WRB diagnostic horizons, properties and materials 81 Appending texture and parent material information to the reference soil group 82
References 85
Annexes 1. Explanation of soil temperature regimes 87 2. Explanation of soil moisture regimes 91 3. Equipment necessary for field work 97
710 vi
List of tables
1. Soil profile description status 6 2. Codes for weather conditions 9 3. Soil temperature and moisture regime codes 10 4. Hierarchy of major landforms 11 5. Subdivisions for complex landforms 11 6. Classification of slope forms 12 7. Slope gradient classes 12 8. Land-use classification 14 9. Crop codes 15 10. Recommended codes for human influence 15 11. Vegetation classification 16 12. Hierarchy of lithology 18 13. Provisional coding for age of land surface 19 14. Recommended classification of rock outcrops 21 15. Classification of coarse surface fragments 22 16. Classification of erosion, by category 22 17. Classification of total area affected by erosion and deposition 22 18. Classification of erosion, by degree 22 19. Classification of erosion, by activity 23 20. Classification of attributes of surface sealing 23 21. Classification of surface cracks 24 22. Classification of salt characteristics 24 23. Classification of bleached sand characteristics 24 24. Classification of horizon boundaries, by distinctness and topography 25 25. Key to the soil textural classes 28 26. Abundance of rock fragments and artefacts, by volume 29 27. Classification of rock fragments and artefacts 30 28. Classification of shape of rock fragments 31 29. Classification of weathering of coarse fragments 31 30. Codes for primary mineral fragments 31 31. Field estimation and coding of the degree of decomposition and humification of peat 32 32. Classification of the abundance of mottles 35 33. Classification of the size of mottles 35 34. Classification of the contrast of mottles 36 35. Classification of boundary between mottle and matrix 36
711 vii
36. Redoximorphic soil characteristics and their relation to rH values and soil processes 36 37. Reductimorphic colour pattern and occurrence of Fe compounds 37 38. Classification of carbonate reaction in the soil matrix 38 39. Classification of forms of secondary carbonates 38 40. Classification of gypsum content 39 41. Classification of forms of secondary gypsum 39 42. Classification of salt content of soil 40 43. Dependency of water content of saturation extract on texture and content of humus for mineral soils and on decomposition for peat soils 41 44. Classification of pH value 41 45. Classification of soil odour 42 46. Estimation of organic matter content based on Munsell soil colour 43 47. Classification of structure of pedal soil materials 45 48. Classification of types of soil structure 46 49. Codes for types of soil structure 46 50. Size classes for soil structure types 47 51. Combined size classes for soil structure types 47 52. Combinations of soil structures 47 53. Consistence of soil mass when dry 48 54. Consistence of soil mass when moist 49 55. Classification of soil stickiness 49 56. Classification of soil plasticity 49 57. Classification of moisture status of soil 50 58. Field estimation of bulk density for mineral soils 51 59. Field estimation of volume of solids and bulk density of peat soils 52 60. Classification of porosity 52 61. Classification of voids 53 62. Classification of diameter of voids 53 63. Classification of abundance of pores 53 64. Classification of abundance of coatings 55 65. Classification of the contrast of coatings 55 66. Classification of the nature of coatings 55 67. Classification of the form of coatings 56 68. Classification of the location of coatings and clay accumulation 56 69. Classification of the continuity of cementation/compaction 56 70. Classification of the fabric of the cemented/compacted layer 56 71. Classification of the nature of cementation/compaction 57 72. Classification of the degree of cementation/compaction 57 73. Classification of the abundance of mineral concentrations, by volume 58
712 viii
74. Classification of the kinds of mineral concentrations 58 75. Classification of the size and shape of mineral concentrations 58 76. Classification of the hardness of mineral concentrations 58 77. Examples of the nature of mineral concentrations 59 78. Colour names of mineral concentrations 59 79. Classification of the diameter of roots 60 80. Classification of the abundance of roots 60 81. Classification of the abundance of biological activity 60 82. Examples of biological features 60 83. Classification of kinds of artefacts 63 84. Determination table and codes for human-made deposits 64 85. Subordinate characteristics within master horizons 72 86. Checklist of WRB diagnostic horizons, properties and materials 81
List of figures
1. The process of soil description, classification, site quality and suitability evaluation 1 2. Slope positions in undulating and mountainous terrain 11 3. Slope forms and surface pathways 12 4. Relation of constituents of fine earth by size, defining textural classes and sand subclasses 27 5. Charts for estimating proportions of coarse fragments and mottles 30 6. Soil structure types and their formation 45 7. Qualification of bulk density 51 8. Charts for estimating size and abundance of pores 54
713 ix
Acknowledgements
This revision was prepared by R. Jahn (University of Halle-Wittenberg), H.-P. Blume (University of Kiel), V.B. Asio (Leyte State University), O. Spaargaren (ISRIC) and P. Schad (Technische Universität München), with contributions and suggestions from R. Langohr (University Gent), R. Brinkman (FAO), F.O. Nachtergaele (FAO) and R. Pavel Krasilnikov (Universidad Nacional Autónoma de México).
714 x
List of acronyms
EC Electrical conductivity GPS Global Positioning System HDPE High-density polyethylene HTM Human-transported material ISO International Organization for Standardization PVC Polyvinyl chloride RSG Reference Soil Group USDA United States Department of Agriculture UTM Universal Transverse Mercator WRB World Reference Base for Soil Resources
715 1
Chapter 1 Introduction
The main objective of research in soil science is the understanding of the nature, properties, dynamics and functions of the soil as part of landscapes and ecosystems. A basic requirement for attaining that objective is the availability of reliable information on soil morphology and other characteristics obtained through examination and description of the soil in the field. It is important that soil description be done thoroughly; it serves as the basis for soil classification and site evaluation as well as interpretations on the genesis and environmental functions of the soil. A good soil description and the derived knowledge on the genesis of the soil are also powerful tools to guide, help explain and regulate costly laboratory work. It can also prevent errors in soil sampling. Figure 1 shows the role of soil description as an early step to classification, soil and site assessment, and suitability evaluation.
FIGURE 1 The process of soil description, classification, site quality and suitability evaluation
1. Registration, Number, author, date, location description status, locality
2. Soil formation Climate, landform, parent factors material, land use, vegetation, age and history of landscape
3. Horizons and layers Identification of boundries Observations For each horizon/layer: and measurements Characteristics of rock fragments, texture, colour, horizons/layers pH, carbonates, structure, bulk- density, biological activity, ...
4. Interpretation of soil Qualities of 5. formation processes horizons
Genetic and Interpretation Designation systematic Qualities of soil of ecological of horizons interpretation site qualities (classification)
Identification of Site qualities soil unit
Suitability evaluation comparison of land use requirements with site qualities
716 2 Guidelines for soil description
Soils are affected by human activities, such as industrial, municipal and agriculture, that often result in soil degradation and loss or reduction in soil functions. In order to prevent soil degradation and to rehabilitate the potentials of degraded soils, reliable soil data are the most important prerequisite for the design of appropriate land-use systems and soil management practices as well as for a better understanding of the environment. With the present internationalization, the use of a common language is of prime importance, also in soil science. The increasing need for internationally accepted rules and systems of soil description and soil classification led to the development of various soil classification concepts, e.g. the FAO–UNESCO Legend for the Soil Map of the World (FAO–UNESCO, 1974, 1988) and Soil Taxonomy (USDA Soil Survey Staff 1975, 1999), and soil maps, e.g. the Soil Map of the World (FAO– UNESCO, 1970–1981; FAO, 2002), Soil Map of the European Communities (ECSC–EEC–EAEC, 1985), and Soil Atlas of Europe (EC, 2005). These guidelines are based on the internationally accepted Guidelines for Soil Description (FAO, 1990). Some new international developments in soil information systems and soil classification, such as the Field Book for Describing and Sampling Soils (Schoeneberger et al., 2002) and Keys to Soil Taxonomy (USDA Soil Survey Staff, 2003), Updated Global and National Soils and Terrain Digital Databases (ISRIC, 2005) and the second edition of the World Reference Base for Soil Resources (IUSS Working Group WRB, 2006) are taken into consideration. For practical reasons, the contents of the major sources were modified, shortened and rearranged. Specifically, the various chapters of this field guide were based on the following sources: ¾Chapter 2 on general site description – Guidelines for Soil Description (FAO, 1990). ¾Chapter 3 on the description of soil forming factors – Guidelines for Soil Description (FAO, 1990); updated SOTER (ISRIC, 2005); Field Book for Describing and Sampling Soils (Schoeneberger et al., 2002); and Keys to Soil Taxonomy (USDA Soil Survey Staff, 2003). ¾Chapter 4 on soil description – Guidelines for Soil Description (FAO, 1990) and partly the German Mapping Guide 5 (Kartieranleitung 5; Ad- hoc-AG-Boden, 2005), the material of DVWK (1995), Field Book for Describing and Sampling Soils (Schoeneberger et al., 2002), as well as the personal experiences of the authors. ¾Chapter 5 on horizon designation and soil classification – Guidelines for Soil Description (FAO, 1990), Field Book for Describing and Sampling Soils (Schoeneberger et al., 2002), Keys to Soil Taxonomy (USDA Soil Survey Staff, 2003) and the second edition of the World Reference Base for Soil Resources (IUSS Working Group WRB, 2006). To help beginners, some explanatory notes are included as well as keys based on simple tests and observations for the determination of soil characteristics. The guidelines provide a complete procedure for soil description and for collecting field data necessary for classification according to second edition of the
717 Chapter 1 – Introduction 3
World Reference Base for Soil Resources (WRB) (IUSS Working Group WRB, 2006). Notes for classification purposes are added to each chapter and explain the relevance of the described feature for classification according to the WRB. In order to avoid being excessively lengthy, it is not stated whether the described feature is a required one or is one of two or more options.
718 719 5
Chapter 2 General site information, registration and location
Before any actual soil description should be done, it is necessary to take note of some relevant information related to the registration and identification of the soil to be described, such as profile number, description status, date of description, author, location, elevation, map sheet number, and grid reference. This information is necessary for easy referencing and retrieval of the soil description from data storage systems.
PROFILE NUMBER The profile number or profile identification code should be constructed in such a way that it meets local needs and also allows easy and simple retrieval of profile descriptions from computerized data storage systems. The profile identification code should be constructed from a combination of a location letter code and a profile number code. The letter code should consist of a practical selection of codes referring to a country, preferably the internationally accepted International Organization for Standardization (ISO) code, a topographic map reference or any other defined area or town. Example: DE/ST/HAL -0381 = Halle in Saxony- Anhalt in Germany, profile 381.
SOIL PROFILE DESCRIPTION STATUS The status of the soil profile description refers to the quality of the soil description and the analytical data. The status is allocated after completion of the analyses and is indicative of the reliability of soil profile information entered into a database. Table 1 lists the possible descriptions.
DATE OF DESCRIPTION It is important to always indicate the date of description in order to inform future users of the soil data as to how old the data are. The date of description is given as: yymmdd (six digits). For example, 8 January 2006 would be coded 060108.
AUTHORS The persons who perform the description need to be acknowledged properly in future uses of the soil data. In addition, they hold responsibility for the quality of the data. The names or initials of the authors are given.
720 6 Guidelines for soil description
TABLE 1 Soil profile description status Status 1 Reference profile description No essential elements or details are missing from the description, sampling or analysis. The accuracy and reliability of the description and analytical results permit the full characterization of all soil horizons to a depth of 125 cm, or more if required for classification, or down to a C or R horizon or layer, which may be shallower. 1.1 If soil description is done without sampling. 2 Routine profile description No essential elements are missing from the description, sampling or analysis. The number of samples collected is sufficient to characterize all major soil horizons, but may not allow precise definition of all subhorizons, especially in the deeper soil. The profile depth is 80 cm or more, or down to a C or R horizon or layer, which may be shallower. Additional augering and sampling may be required for lower level classification. 2.1 If soil description is done without sampling. 3 Incomplete description Certain relevant elements are missing from the description, an insufficient number of samples was collected, or the reliability of the analytical data does not permit a complete characterization of the soil. However, the description is useful for specific purposes and provides a satisfactory indication of the nature of the soil at high levels of soil taxonomic classification. 3.1 If soil description is done without sampling. 4 Soil augering description Soil augerings do no permit a comprehensive soil profile description. Augerings are made for routine soil observation and identification in soil mapping, and for that purpose normally provide a satisfactory indication of the soil characteristics. Soil samples may be collected from augerings. 4.1 If soil description is done without sampling. 5 Other descriptions Essential elements are missing from the description, preventing a satisfactory soil characterization and classification. Note: Descriptions from soil augerings or from other observations made for routine soil mapping are either kept on ordinary field data sheets or included in the database, with an appropriate indication of status.
LOCATION A description of the soil location should be given. It should be as precise as possible in terms of the distance (in metres or kilometres) and direction to the site from permanent features that are recognizable in the field and on the topographic map. Distances along roads or traverses relate to a marked reference point (0.0 km). The description of the location should be such that readers who are unfamiliar with the area are able to locate the approximate position of the site. The administrative units, such as region, province, district, country or locality, are given in the profile number section (above). Example: Agricultural research station Bad Lauchstädt, Sachsen-Anhalt.
ELEVATION The elevation of the site relative to sea level should be obtained as accurately as possible, preferably from detailed contour or topographic maps. Where such information is not available, the best possible estimate is made from general maps or by altimeter readings. At present, determination of elevation by the Global Positioning System (GPS) unit is inaccurate and unacceptable. Elevation is given in metres (1 foot = 0.3048 m).
721 Chapter 2 – General site information, registration and location 7
MAP SHEET NUMBER AND GRID REFERENCE (COORDINATES) The number of the topographic map sheet, preferably at 1:25 000 or 1:50 000 scale, on which the soil observation occurs is given. Example: TK50 L4536 Halle (Saale) = Topographic map 1:50 000 Number L4536 of Halle. The grid reference number, Universal Transverse Mercator (UTM) or the established local system, can be read directly from the topographic map. The latitude and longitude of the site are given as accurately as possible (in degrees, minutes, seconds and decimal seconds); they can be derived directly from topographic maps or a GPS unit. Example: H: 56.95.250 or latitude: 51° 23´ 30.84´´ N; R: 44.91.600 or longitude: 11° 52´ 40.16´´ E. Some countries use their own zero longitude, e.g. Italian topographic maps show the Monte Mario meridian at Rome as zero. For international use, these should be converted to the zero meridian of the Greenwich system.
722 723 9
Chapter 3 Soil formation factors
This chapter provides the guidelines for the description of factors that define the kind and intensity of soil formation processes. These factors are also part of the important site qualities. The information may be derived from a combination of field measurements, climate records, field observations and evaluation of climate, topographical, geological and geomorphological maps and documents. For land use and vegetation, the present conditions are reported.
ATMOSPHERIC CLIMATE AND WEATHER CONDITIONS The climate conditions of a site are important site properties that influence plant growth and soil formation. As minimum climate data, the monthly mean temperature (in degrees Celsius) and the monthly mean precipitation (in millimetres) can be taken from the nearest meteorological station. Where available, the length of the growing period (in days) should be specified. The length of the growing period is defined as the period with humid conditions (excess of precipitation over potential evapotranspiration) during the time with temperature ≥ 5 °C (FAO, 1978). The present as well as the weather conditions days or weeks before the description influence soil moisture and structure, hence these should be noted. In addition, the prevailing general weather conditions and the air temperature TABLE 2 at the time of observation as well Codes for weather conditions as that of the near past should be Present weather conditions (Schoeneberger et al., 2002) documented (Table 2). SU sunny/clear PC partly cloudy OV overcast SOIL CLIMATE RA rain Where applicable, the soil climate SL sleet classification should be indicated. SN snow The soil moisture and temperature Former weather conditions (Ad-hoc-AG-Boden, 2005) regimes according to Keys to Soil WC 1 no rain in the last month Taxonomy (USDA Soil Survey WC 2 no rain in the last week Staff, 2003) may be mentioned WC 3 no rain in the last 24 hours (Table 3; explanations in Annexes 1 WC 4 rainy without heavy rain in the last 24 hours WC 5 heavier rain for some days or rainstorm in the and 2). Where such information is last 24 hours not available or cannot be derived WC 6 extremely rainy time or snow melting from representative climate data Note: For example: SU, 25 °C; WC 2 (= sunny, temperature 25 °C, no with confidence, it is preferable to rain in the last week).
724 10 Guidelines for soil description
TABLE 3 Soil temperature and moisture regime codes Soil temperature regime Soil moisture regime PG = Pergelic AQ = Aquic PQ = Peraquic CR = Cryic DU = Udic PU = Perudic FR = Frigid IF = Isofrigid US = Ustic ME = Mesic IM = Isomesic XE = Xeric TH = Thermic IT = Isothermic AR = Aridic and TO = Torric HT = Hyperthermic IH = Isohyperthermic
leave the space blank. Other agroclimate parameters worth mentioning would be a local climate class, the agroclimate zone, length of growing period, etc.
Note for classification purposes 9Soil temperature < 0 °C (pergelic soil temperature regime) A cryic horizon and Gelic qualifier.
LANDFORM AND TOPOGRAPHY (RELIEF) Landform refers to any physical feature on the earth’s surface that has been formed by natural processes and has a distinct shape. Topography refers to the configuration of the land surface described in four categories: ¾ the major landform, which refers to the morphology of the whole landscape; ¾ the position of the site within the landscape; ¾ the slope form; ¾ the slope angle.
Major landform Landforms are described foremost by their morphology and not by their genetic origin or processes responsible for their shape. The dominant slope is the most important differentiating criterion, followed by the relief intensity (Table 4). The relief intensity is the median difference between the highest and lowest point within the terrain per specified distance. The specified distance can be variable. The relief intensity is normally given in metres per kilometre. With complex landforms, the protruding landform should be at least 25 m high (if not it is to be considered mesorelief) except for terraced land, where the main terraces should have elevation differences of at least 10 m. In areas, the major terraces may be very close to each other – particularly towards the lower part of the plain. Finally, the older levels may become buried by down wash. For complex landforms, subdivisions can be used (Table 5). These subdivisions are mainly applicable to level landforms, to some extent to sloping landforms and, in the case of mountains, to intermontane plains.
Position The relative position of the site within the land should be indicated. The position affects the hydrological conditions of the site (external and internal drainage, e.g.
725 Chapter 3 – Soil formation factors 11
TABLE 4 Hierarchy of major landforms 1st level 2nd level Gradient Relief intensity Potential (%) (m km-1) drainage density L level land LP plain < 10 < 50 0–25 LL plateau < 10 < 50 0–25 LD depression < 10 < 50 16–25 LV valley floor < 10 < 50 6–15 S sloping land SE medium-gradient escarpment zone 10–30 50–100 < 6 SH medium-gradient hill 10–30 100–150 0–15 SM medium-gradient mountain 15–30 150–300 0–15 SP dissected plain 10–30 50–100 0–15 SV medium-gradient valley 10–30 100–150 6–15 T steep land TE high-gradient escarpment zone > 30 150–300 < 6 TH high-gradient hill > 30 150–300 0–15 TM high-gradient mountain > 30 > 300 0–15 TV high-gradient valley > 30 > 150 6–15 Notes: Changes proposed at the SOTER meeting at Ispra, October 2004. Potential drainage density is given in number of “receiving” pixels within a 10 × 10 pixels window. Source: Updated SOTER, ISRIC, 2005.
TABLE 5 Subdivisions for complex landforms CU = Cuesta-shaped DO = Dome-shaped RI = Ridged TE = Terraced IN = Inselberg covered (occupying > 1% of level land) DU = Dune-shaped IM = With intermontane plains (occupying > 15%) KA = Strong karst WE = With wetlands (occupying > 15%) Source: Updated SOTER, ISRIC, 2005.
FIGURE 2 Slope positions in undulating and mountainous terrain
CR CR UP UP
MS MS
Channel LS LS TS BO Alluvium
Note: Position in undulating to mountainous terrain Position in flat or almost flat terrain CR = Crest (summit) HI = Higher part (rise) UP = Upper slope (shoulder) IN = Intermediate part (talf) MS = Middle slope (back slope) LO = Lower part (and dip) LS = Lower slope (foot slope) BO = Bottom (drainage line) TS = Toe slope BO = Bottom (flat) Source: Redrawn from Schoeneberger et al., 2002.
726 12 Guidelines for soil description
TABLE 6 subsurface runoff), which may be Classification of slope forms interpreted as being predominantly Sstraight water receiving, water shedding or C concave V convex neither of these. Tterraced X complex (irregular) Slope form The slope form refers to the general shape of the slope in both the vertical and horizontal directions FIGURE 3 Slope forms and surface pathways (Figure 3). Table 6 lists the slope form classes.
Slope gradient and orientation The slope gradient refers to the SS SV SC slope of the land immediately surrounding the site. It is measured using a clinometer aimed in the direction of the steepest slope. VS VV VC Where clinometer readings are not possible, field estimates of slope gradient should be matched CS CV CC against calculated gradients from contour maps. Surface flow pathway Slope gradients in almost flat terrain are often overestimated. Source: Redrawn from Schoeneberger et al., 2002. In open plains, slope gradients of 0.2 percent are usually clearly TABLE 7 visible. The proper recording of Slope gradient classes minor slope-gradient variations is Class Description % important, especially for erosion, 01 Flat 0–0.2 02 Level 0.2–0.5 irrigation and drainage. 03 Nearly level 0.5–1.0 The slope gradient is recorded 04 Very gently sloping 1.0–2.0 in two ways. The first and most 05 Gently sloping 2–5 important is by means of the 06 Sloping 5–10 actual, measured value, and the 07 Strongly sloping 10–15 second by entering in one of the 08 Moderately steep 15–30 09 Steep 30–60 following classes; they may need 10 Very steep > 60 to be modified to fit the local topography (Table 7). In addition to the attributes of slope in Table 7, both the slope length (particularly above the site) and aspect (orientation) should be recorded. The orientation influences, for example, the precipitation input, the temperature regime, the risk for wind impact and the character of humus formed in higher latitudes.
727 Chapter 3 – Soil formation factors 13
The orientation that a slope is facing is coded N for north, E for east, S for south and W for west; for example, SSW means south-southwest.
LAND USE AND VEGETATION Land use Land use applies to the current use of the land, whether agricultural or non- agricultural, in which the soil is located. Land use has a major influence on the direction and rate of soil formation; its recording enhances the interpretative value of the soil data considerably (Table 8). For arable land use, the dominant crops grown should be mentioned (section on crops [below]), and as much information as possible given on soil management, use of fertilizers, duration of fallow period, rotation systems and yields.
Crops Crops are plants that are cultivated for their economic value. Information on crops is important because it gives an idea of the nature of soil disturbance as a result of crop management practices as well as the nutrient and soil management requirements of the crop. Information on crops can be given in a general or detailed way as required. Examples for the most common crops with their recommended codes are given in Table 9.
Human influence This item refers to any evidence of human activity that is likely to have affected the landscape or the physical and chemical properties of the soil. Erosion is dealt with separately in Chapter 4. For various environments, it is useful to indicate the degree of disturbance of the natural vegetation. The existing vegetation is described in the section on vegetation (below). Examples of human influences with their recommended codes are given in Table 10.
Note for classification purposes 9Constructed terraces A Escalic qualifier. 9Raised land surfaces A plaggic and terric horizons. 9Ploughing A anthraquic and anthric horizons and Aric qualifier. 9Special depth limits if plough layers are present A Fluvisols, Chernozems and Cambisols. 9Special requirements if an eluvial horizon is part of a plough layer A argic and natric horizons. 9Does not form part of a plough layer A cambic horizon. 9Mixing or soil layers or lumps of applied lime A anthric horizon. 9Spade marks A plaggic horizon.
728 14 Guidelines for soil description
TABLE 8 Land-use classification A = Crop agriculture (cropping) AA = Annual field cropping AA1 = Shifting cultivation AA2 = Fallow system cultivation AA3 = Ley system cultivation AA4 = Rainfed arable cultivation AA5 = Wet rice cultivation AA6 = Irrigated cultivation AP = Perennial field cropping AP1 = Non-irrigated cultivation AP2 = Irrigated cultivation AT = Tree and shrub cropping AT1 = Non-irrigated tree crop cultivation AT2 = Irrigated tree crop cultivation AT3 = Non-irrigated shrub crop cultivation AT4 = Irrigated shrub crop cultivation Additional codes may be used to further specify the land-use type. For example: AA4 = Rainfed arable cultivation AA4T = Traditional AA4I = Improved traditional AA4M = Mechanized traditional AA4C = Commercial AA4U = Unspecified M = Mixed farming MF = Agroforestry MP = Agropastoralism H = Animal husbandry HE = Extensive grazing HE1 = Nomadism HE2 = Semi-nomadism HE3 = Ranching HI = Intensive grazing HI1 = Animal production HI2 = Dairying F = Forestry FN = Natural forest and woodland FN1 = Selective felling FN2 = Clear felling FP = Plantation forestry P = Nature protection PN = Nature and game preservation PN1 = Reserves PN2 = Parks PN3 = Wildlife management PD = Degradation control PD1 = Without interference PD2 = With interference S = Settlement, industry SR = Residential use SI = Industrial use ST = Transport SC = Recreational use SX = Excavations SD = Disposal sites Y = Military area O = Other land uses U = Not used and not managed
729 Chapter 3 – Soil formation factors 15
TABLE 9 Crop codes Ce = Cereals Fo = Fodder plants Fi = Fibre crops CeBa = Barley FoAl = Alfalfa FiCo = Cotton CeMa = Maize FoCl = Clover FiJu = Jute CeMi = Millet FoGr = Grasses Ve = Vegetables CeOa = Oats FoHa = Hay Pu = Pulses PuBe = Beans CePa = Rice, paddy FoLe = Leguminous PuLe = Lentils CeRi = Rice, dry FoMa = Maize PuPe = Peas CeRy = Rye FoPu = Pumpkins Lu = Semi-luxury foods and tobacco CeSo = Sorghum Ro = Roots and tubers RoCa = Cassava LuCc = Cocoa CeWh = Wheat RoPo = Potatoes LuCo = Coffee Oi = Oilcrops OiCc = Coconuts RoSu = Sugar beets LuTe = Tea OiGr = Groundnuts RoYa = Yams LuTo = Tobacco OiLi = Linseed Fr = Fruits and melons Ot = Other crops FrAp = Apples OtSc = Sugar cane OiOl = Olives FrBa = Bananas OtRu = Rubber OiOp = Oil-palm FrCi = Citrus OtPa = Palm (fibres, OiRa = Rape FrGr = Grapes, Wine, kernels) OiSe = Sesame Raisins OiSo = Soybeans FrMa = Mangoes OiSu = Sunflower FrMe = Melons
TABLE 10 Recommended codes for human influence N = No influence BU = Bunding NK = Not known BR = Burning VS = Vegetation slightly disturbed TE = Terracing VM = Vegetation moderately disturbed PL = Ploughing VE = Vegetation strongly disturbed MP = Plaggen VU = Vegetation disturbed (not specified) MR = Raised beds (agricultural purposes) IS = Sprinkler irrigation ME = Raised beds (engineering purposes) IF = Furrow irrigation MS = Sand additions ID = Drip irrigation MU = Mineral additions (not specified) IP = Flood irrigation MO = Organic additions (not specified) IB = Border irrigation PO = Pollution IU = Irrigation (not specified) CL = Clearing AD = Artificial drainage SC = Surface compaction FE = Application of fertilizers SA = Scalped area LF = Landfill (also sanitary) BP = Borrow pit LV = Levelling DU = Dump (not specified) AC = Archaeological (burial mound, midden) MI = Mine (surface, including openpit, gravel and quarries) CR = Impact crater
730 16 Guidelines for soil description
TABLE 11 Vegetation classification F = Closed forest 1 D = Dwarf shrub FE = Evergreen broad-leaved forest DE = Evergreen dwarf shrub FC = Coniferous forest DS = Semi-deciduous dwarf shrub FS = Semi-deciduous forest DD = Deciduous dwarf shrub FD = Deciduous forest DX = Xermomorphic dwarf shrub FX = Xeromorphic forest DT = Tundra W = Woodland 2 H = Herbaceous WE = Evergreen woodland HT = Tall grassland WS = Semi-deciduous woodland HM = Medium grassland WD = Deciduous woodland HS = Short grassland WX = Xeromorphic woodland HF = Forb S = Shrub M = Rainwater-fed moor peat SE = Evergreen shrub B = Groundwater-fed bog peat SS = Semi-deciduous shrub SD = Deciduous shrub SX = Xeromorphic shrub 1 Continuous tree layer, crowns overlapping, large number of tree and shrub species in distinct layers. 2 Continuous tree layer, crowns usually not touching, understorey may be present.
Vegetation Vegetation is a dominant factor in soil formation as it is the primary source of organic matter and because of its major role in the nutrient cycling and hydrology of a site. There is no uniform acceptance of a system for the description of the natural or semi-natural vegetation. The kind of vegetation can be described using a local, regional or international system. A common example is the vegetation classification according to UNESCO (1973, see updated SOTER; ISRIC, 2005), presented in Table 11 with codes added. In addition, other characteristics of the vegetation, such as height of trees or canopy cover, may be recorded.
PARENT MATERIAL The parent material is the material from which the soil has presumably been derived. The parent material should be described as accurately as possible, indicating its origin and nature. There are basically two groups of parent material on which the soil has formed: unconsolidated materials (mostly sediments); and weathering materials overlying the hard rock from which they originate. There are transitional cases, such as partly consolidated materials and weathering materials that have been transported, either by water, called alluvium (fluvial if transported by stream), or by gravity, called colluvium. There are also restored natural soil materials or sediments as well as technogenic materials. The reliability of the geological information and the knowledge of the local lithology will determine whether a general or a specific definition of the parent material can be given.
731 Chapter 3 – Soil formation factors 17
For weathered rock, the code WE is first entered, followed by the rock-type code. The code SA for saprolite is recommended where the in situ weathered material is thoroughly decomposed, clay-rich but still showing rock structure. Alluvial deposits and colluvium derived from a single rock type may be further specified by that rock type. Where one parent material overlies another, both are indicated. The parent material is coded according to updated SOTER (ISRIC, 2005) at the lowest level of hierarchy as possible. As SOTER was developed to work with maps on a scale of 1:1 000 000, it was a requirement to have not too many rock types. In order to be able to work in smaller scales, some additional natural and anthropogenic parent materials are included in Table 12. For identification in the field, a key to the most important rock types is provided below the extended hierarchical SOTER list.
Note for classification purposes 9Remains intact when a specimen of 25–30 mm is submerged in water for 1 hour; roots cannot penetrate except along vertical cracks that have an average horizontal spacing of ≥ 10 cm and that occupy < 20 percent (by volume); no significant displacement has taken place A continuous rock. 9Differences in lithology A lithological discontinuity. 9Recent sediments above the soil that is classified at the Reference Soil Group (RSG) level A Novic qualifier. 9Sedimentation through human-induced erosion A colluvic material. 9Coprogenous earth or sedimentary peat, diatomaceous earth, marl or gyttja A limnic material. 9Remnants of birds or bird activity A ornithogenic material. 9Organic material consisting of ≥ 75 percent of moss fibres A greater thickness of organic material required for Histosols. 9Moor peat saturated predominantly with rainwater A Ombric qualifier. 9Bog peat saturated predominantly with groundwater or flowing surface water A Rheic qualifier.
AGE OF THE LAND SURFACE The age of the landscape is important information from which the possible duration of the occurrence of soil formation processes can be derived. Because many soils are formed from preweathered or moved materials, or may have been derived from an assemblage of autochthonous, fluvial and eolian materials, it is often difficult to obtain precise information. However, an estimate will help to interpret soil data and interaction between different soil forming processes. It may also indicate possible climate changes during soil formation. Table 13 provides a provisional coding.
732 18 Guidelines for soil description
TABLE 12 Hierarchy of lithology Major class Group Type I igneous rock IA acid igneous IA1 diorite IA2 grano-diorite IA3 quartz-diorite IA4 rhyolite II intermediate igneous II1 andesite, trachyte, phonolite II2 diorite-syenite IB basic igneous IB1 gabbro IB2 basalt IB3 dolerite IU ultrabasic igneous IU1 peridotite IU2 pyroxenite IU3 ilmenite, magnetite, ironstone, serpentine IP pyroclastic IP1 tuff, tuffite IP2 volcanic scoria/breccia IP3 volcanic ash IP4 ignimbrite M metamorphic rock MA acid metamorphic MA1 quartzite MA2 gneiss, migmatite MA3 slate, phyllite (pelitic rocks) MA4 schist MB basic metamorphic MB1 slate, phyllite (pelitic rocks) MB2 (green)schist MB3 gneiss rich in Fe–Mg minerals MB4 metamorphic limestone (marble) MB5 amphibolite MB6 eclogite MU ultrabasic metamorphic MU1 serpentinite, greenstone S sedimentary rock SC clastic sediments SC1 conglomerate, breccia (consolidated) SC2 sandstone, greywacke, arkose SC3 silt-, mud-, claystone SC4 shale SC5 ironstone SO carbonatic, organic SO1 limestone, other carbonate rock SO2 marl and other mixtures SO3 coals, bitumen and related rocks SE evaporites SE1 anhydrite, gypsum SE2 halite U sedimentary rock UR weathered residuum UR1 bauxite, laterite (unconsolidated) UF fluvial UF1 sand and gravel UF2 clay, silt and loam UL lacustrine UL1 sand UL2 silt and clay UM marine, estuarine UM1 sand UM2 clay and silt UC colluvial UC1 slope deposits UC2 lahar UE eolian UE1 loess UE2 sand UG glacial UG1 moraine UG2 glacio-fluvial sand UG3 glacio-fluvial gravel UK * kryogenic UK1 periglacial rock debris UK2 periglacial solifluction layer
733 Chapter 3 – Soil formation factors 19
TABLE 12 Hierarchy of lithology (Continued) Major class Group Type UO organic UO1 rainwater-fed moor peat UO2 groundwater-fed bog peat UA anthropogenic/ UA1 redeposited natural material technogenic UA2 industrial/artisanal deposits UU * unspecified deposits UU1 clay UU2 loam and silt UU3 sand UU4 gravelly sand UU5 gravel, broken rock * Extended. Source: Updated SOTER; ISRIC, 2005.
Materials (natural and anthropogenic/technogenic) deposited by humans are coded: ¾ d... = dumped, ¾ s... = spoiled. Chapter 4 provides more details on human-made materials.
TABLE 13 Provisional coding for age of land surface vYn Very young (1–10 years) natural: with loss by erosion or deposition of materials such as on tidal flats, of coastal dunes, in river valleys, landslides or desert areas. vYa Very young (1–10 years) anthropogeomorphic: with complete disturbance of natural surfaces (and soils) such as in urban, industrial and mining areas with very early soil development from fresh natural or technogenic or mixed materials. Yn Young (10–100 years) natural: with loss by erosion or deposition of materials such as on tidal flats, of coastal dunes, river valleys, landslides or desert areas. Ya Young (10–100 years) anthropogeomorphic: with complete disturbance of any natural surfaces (and soils) such as in urban, industrial and mining areas with early soil development from fresh natural, technogenic or a mixture of materials, or restriction of flooding by dykes. Hn Holocene (100–10 000 years) natural: with loss by erosion or deposition of materials such as on tidal flats, of coastal dunes, in river valleys, landslides or desert areas. Ha Holocene (100–10 000 years) anthropogeomorphic: human-made relief modifications, such as terracing of forming hills or walls by early civilizations or during the Middle Ages or earlier, restriction of flooding by dykes, or surface raising. lPi Late Pleistocene, ice covered, commonly recent soil formation on fresh materials. lPp Late Pleistocene, periglacial, commonly recent soil formation on preweathered materials. lPf Late Pleistocene, without periglacial influence. oPi Older Pleistocene, ice covered, commonly the recent soil formation on younger over older, preweathered materials. oPp Older Pleistocene, with periglacial influence, commonly the recent soil formation on younger over older, preweathered materials. oPf Older Pleistocene, without periglacial influence. T Tertiary land surfaces, commonly high planes, terraces or peneplains, except incised valleys, frequent occurrence of palaeosoils. O Older, pre-Tertiary land surfaces, commonly high planes, terraces or peneplains, except incised valleys, frequent occurrence of palaeosoils.
734 735 21
Chapter 4 Soil description
This chapter presents the procedure to describe the different morphological and other characteristics of the soil. This is best done using a recently dug pit large enough to allow sufficient examination and description of the different horizons. Old exposures such as road cuts and ditches may be used, but only after scraping off sufficient material to expose the fresh soil. First, the surface characteristics are recorded. Then, the soil description is done horizon by horizon, starting with the uppermost one. The rules of soil description and the coding of attributes are generally based on the guidelines for soil description according to FAO (1990). Additions have a citation.
SURFACE CHARACTERISTICS Where present, surface characteristics, such as rock outcrops, coarse rock fragments, human-induced erosion, surface sealing and surface cracks, should be recorded. A number of other surface characteristics, such as the occurrence of salts, bleached sands, litter, worm casts, ant paths, cloddiness, and puddling, may be also be recorded.
Rock outcrops Exposures of bedrock may limit the use of modern mechanized agricultural equipment. Rock outcrops should be described in terms of percentage surface cover, together with additional relevant information on the size, spacing and hardness of the individual outcrops. Table 14 lists the recommended classes of percentage of surface cover and of average distance between rock outcrops (single or clusters).
Coarse surface fragments TABLE 14 Coarse surface fragments, Recommended classification of rock outcrops Distance between rock including those partially exposed, Surface cover (%) outcrops should be described in terms of (m) percentage of surface coverage N None 0 and of size of the fragments. V Very few 0–2 1 > 50 F Few 2–5 2 20–50 Classes of occurrence of coarse C Common 5–15 3 5–20 surface fragments are correlated M Many 15–40 4 2–5 with the ones for rock outcrop, as A Abundant 40–80 5 < 2 per Table 15. D Dominant > 80
736 22 Guidelines for soil description
TABLE 15 Note for classification purposes Classification of coarse surface fragments 9Pavement (consisting of rock Size classes (indicating the Surface cover (%) greatest dimension) outcrops or surface coarse (cm) fragments) that is varnished or N None 0 F Fine gravel 0.2–0.6 includes wind-shaped gravel or V Very few 0–2 M Medium gravel 0.6–2.0 stones or is associated with a F Few 2–5 C Coarse gravel 2–6 vesicular layer A yermic horizon. C Common 5–15 S Stones 6–20 M Many 15–40 B Boulders 20–60 A Abundant 40–80 L Large boulders 60–200 Erosion D Dominant > 80 In describing soil erosion, emphasis should be given to accelerated or TABLE 16 human-induced erosion. It is not Classification of erosion, by category always easy to distinguish between N No evidence of erosion natural and accelerated erosion W Water erosion or A Wind (aeolian) erosion or deposition deposition as they are often closely related. WS Sheet erosion AD Wind deposition Human-induced erosion is the WR Rill erosion AM Wind erosion and result of irrational use and poor deposition WG Gully erosion AS Shifting sands management, such as inappropriate WT Tunnel erosion AZ Salt deposition agricultural practices, overgrazing WD Deposition by water and removal or overexploitation of WA Water and wind erosion the natural vegetation. M Mass movement (landslides and similar phenomena) NK Not known Main categories Erosion can be classified as water or wind erosion (Table 16), and TABLE 17 Classification of total area affected by erosion and include off-site effects such as deposition deposition; a third major category % is mass movements (landslides and 00related phenomena). 1 0–5 2 5–10 Area affected 3 10–25 4 25–50 The total area affected by erosion 5> 50and deposition is estimated follow- ing the classes defined by SOTER (FAO, 1995) as per Table 17. TABLE 18 Classification of erosion, by degree Degree S Slight Some evidence of damage to surface horizons. Original biotic functions largely intact. It is difficult to define classes of M Moderate Clear evidence of removal of surface horizons. the degree of erosion that would Original biotic functions partly destroyed. be equally appropriate for all soils V Severe Surface horizons completely removed and subsurface horizons exposed. Original biotic and environments and that would functions largely destroyed. also fit the various types of water E Extreme Substantial removal of deeper subsurface horizons (badlands). Original biotic functions and wind erosion. Four classes are fully destroyed. recommended (Table 18), which
737 Chapter 4 – Soil description 23
may have to be further defined TABLE 19 for each type or combination of Classification of erosion, by activity A Active at present erosion and deposition and specific R Active in recent past (previous 50–100 years) environment. For example, in the H Active in historical times case of gully and rill erosion, the N Period of activity not known depth and spacing may need to be X Accelerated and natural erosion not distinguished recorded; for sheet erosion, the loss of topsoil; for dunes, the height; and for deposition, the thickness of the layer.
Activity The period of activity of accelerated erosion or deposition is described using the recommended classes in Table 19.
Note for classification purposes 9Evidence of aeolian activity: rounded or subangular sand particles showing a matt surface; wind-shaped rock fragments; aeroturbation; wind erosion or sedimentation A aridic properties.
Surface sealing Surface sealing is used to describe crusts that develop at the soil surface after the topsoil dries out. These crusts may inhibit seed germination, reduce water infiltration and increase runoff. The attributes of surface sealing are the consistence, when dry, and thickness of the crust as per Table 20.
Note for classification purposes 9Surface crust that does not curl entirely upon drying A takyric horizon. 9Surface crust A Hyperochric qualifier.
Surface cracks Surface cracks develop in shrink–swell clay-rich soils after they dry out. The width (average, or average width and maximum width) of the cracks at the surface is indicated in centimetres. The average distance between cracks may also be indicated in centimetres. Table 21 lists the suggested classes.
Note for classification purposes 9Cracks that open and close TABLE 20 periodically A Vertisols. Classification of attributes of surface sealing 9Cracks that open and close Thickness Consistence (mm) periodically, ≥ 1 cm wide A N None S Slightly hard vertic properties. F Thin < 2 H Hard 9Polygonal cracks extending ≥ M Medium 2–5 V Very hard 2 cm deep when the soil is dry C Thick 5–20 E Extremely hard A takyric horizon. V Very thick > 20
738 24 Guidelines for soil description
TABLE 21 Other surface characteristics Classification of surface cracks A number of other surface Width Distance between cracks characteristics, such as the (cm) (m) F Fine < 1 C Very closely spaced < 0.2 occurrence of salts, bleached M Medium 1–2 D Closely spaced 0.2–0.5 sands, litter, worm casts, ant paths, W Wide 2–5 M Moderately widely 0.5–2 cloddiness and puddling, may be spaced V Very wide 5–10 W Widely spaced 2–5 recorded. E Extremely wide > 10 V Very widely spaced > 5 Depth Salt S Surface < 2 The occurrence of salt at the M Medium 2–10 surface may be described in terms D Deep 10–20 of cover, appearance and type of V Very deep > 20 salt. Table 22 lists the classes for
TABLE 22 the percentage of surface cover and Classification of salt characteristics thickness. Cover Thickness (%) (mm) Note for classification purposes 0 None 0–2 N None 9Crust pushed up by salt crystals 1 Low 2–15 F Thin < 2 A Puffic qualifier. 2 Moderate 15–40 M Medium 2–5 3 High 40–80 C Thick 5–20 Bleached sand 4 Dominant > 80 V Very thick > 20 The presence of bleached, loose TABLE 23 sand grains on the surface is typical Classification of bleached sand characteristics for certain soils and influences the % reflection characteristics of the area 0 None 0–2 and, hence, the image obtained 1 Low 2–15 through remote sensing. Table 23 2 Moderate 15–40 3 High 40–80 lists the classes based on the 4 Dominant > 80 percentage of surface covered.
HORIZON BOUNDARY Horizon boundaries provide information on the dominant soil-forming processes that have formed the soil. In certain cases, they reflect past anthropogenic impacts on the landscape. Horizon boundaries are described in terms of depth, distinctness and topography.
Depth Most soil boundaries are zones of transition rather than sharp lines of division. The depth of the upper and lower boundaries of each horizon is given in centimetres, measured from the surface (including organic and mineral covers) of the soil downwards. Precise notations in centimetres are used where boundaries are abrupt or clear. Rounded-off figures (to the nearest 5 cm) are entered where the boundaries are gradual or diffuse, avoiding the suggestion of spurious levels of accuracy.
739 Chapter 4 – Soil description 25
However, if boundary depths are TABLE 24 near diagnostic limits, rounded- Classification of horizon boundaries, by distinctness and topography off figures should not be used. In Distinctness Topography this case, the depth is indicated as (cm) a medium value for the transitional A Abrupt 0–2 S Smooth Nearly plane surface zone (if it starts at 16 cm and C Clear 2–5 W Wavy Pockets less deep than terminates at 23 cm, the depth wide G Gradual 5–15 I Irregular Pockets more deep than should be 19.5 cm). wide Most horizons do not have a D Diffuse > 15 B Broken Discontinuous constant depth. The variation or irregularity of the surface of the boundary is described by the topography in terms of smooth, wavy, irregular and broken. If required, ranges in depth should be given in addition to the average depth, for example 28 (25–31) cm to 45 (39–51) cm.
Note for classification purposes 9Many diagnostic horizons and properties are found at a certain depth. Important boundary depths are 10, 20, 25, 40, 50, 100 and 120 cm.
Distinctness and topography The distinctness of the boundary refers to the thickness of the zone in which the horizon boundary can be located without being in one of the adjacent horizons (Table 24). The topography of the boundary indicates the smoothness of depth variation of the boundary.
Note for classification purposes 9Cryoturbation A cryic horizon, Cryosols and Turbic qualifier. 9Tonguing of a mollic or umbric horizon into an underlying layer A Glossic qualifier. 9Tonguing of an eluvial albic horizon into an argic horizon A albeluvic tonguing and Glossalbic qualifier. 9Diffuse horizon boundaries A Nitisols.
PRIMARY CONSTITUENTS This section presents the procedure on the description of soil texture and the nature of the primary rock and mineral fragments, which are subdivided into: (i) the fine earth fraction; and (ii) the coarse fragments fraction.
Texture of the fine earth fraction Soil texture refers to the proportion of the various particle-size classes (or soil separates, or fractions) in a given soil volume and is described as soil textural class (Figure 4). The names for the particle-size classes correspond closely with commonly used standard terminology, including that of the system used by the
740 26 Guidelines for soil description
United States Department of Agriculture (USDA). However, many national systems describing particle-size and textural classes use more or less the same names but different grain fractions of sand, silt and clay, and textural classes. This publication uses the 2000–63–2-μm system for particle-size fractions.
Soil textural classes The names of the textural classes (which describe combined particle-size classes) of the described soil material are coded as in Figure 4. In addition to the textural class, a field estimate of the percentage of clay is given. This estimate is useful for indicating increases or decreases in clay content within textural classes, and for comparing field estimates with analytical results. The relationship between the basic textural classes and the percentages of clay, silt and sand is indicated in a triangular form in Figure 4.
Subdivision of the sand fraction Sands, loamy sands and sandy loams are subdivided according to the proportions of very coarse to coarse, medium, fine and very fine sands in the sand fraction. The proportions are calculated from the particle-size distribution, taking the total of the sand fraction as being 100 percent (Figure 4).
Field estimation of textural classes The textural class can be estimated in the field by simple field tests and feeling the constituents of the soil (Table 25). For this, the soil sample must be in a moist to weak wet state. Gravel and other constituents > 2 mm must be removed. The constituents have the following feel: ¾Clay: soils fingers, is cohesive (sticky), is formable, has a high plasticity and has a shiny surface after squeezing between fingers. ¾Silt: soils fingers, is non-sticky, only weakly formable, has a rough and ripped surface after squeezing between fingers and feels very floury (like talcum powder). ¾Sand: cannot be formed, does not soil fingers and feels very grainy.
Note for classification purposes Important diagnostic characteristics derived from the textural class are: 9A texture that is loamy sand or coarser to a depth of ≥ 100 cm A Arenosol. 9A texture of loamy fine sand or coarser in a layer ≥ 30 cm thick within 100 cm of the soil surface A Arenic qualifier. 9A texture of silt, silt loam, silty clay loam or silty clay in a layer ≥ 30 cm thick, within 100 cm of the soil surface A Siltic qualifier. 9A texture of clay in a layer ≥ 30 cm thick within 100 cm of the soil surface A Clayic qualifier. 9≥ 30 percent clay throughout a thickness of 25 cm A vertic horizon. 9≥ 30 percent clay throughout a thickness of 15 cm A vertic properties. 9≥ 30 percent clay between the soil surface and a vertic horizon A Vertisol.
741 Chapter 4 – Soil description 27
FIGURE 4 Relation of constituents of fine earth by size, defining textural classes and sand subclasses Particle-size classes Textural classes 2 000 μm Very coarse sand S Sand (unspecified) 1 250 μm Coarse sand LS Loamy sand 630 μm Medium sand SL Sandy loam 200 μm Fine sand SCL Sandy clay loam 125 μm Very fine sand SiL Silt loam 63 μm Coarse silt SiCL Silty clay loam 20 μm Fine silt CL Clay loam 2 μm 0 Clay 100 L Loam Si Silt SC Sandy clay SiC Silty clay Silt/clay C Clay 0.4 HC Heavy clay (Heavy clay) 0.6
% Clay 50 % Silt <2 μm 50 Clay Silty 2 – 63 μm Sandy clay clay (Vertic horizon) Clay loam Silt clay Sandy clay loam loam Loam (Arenosols) Sandy Silt loam Loamy loam Silt Sand Sand 100 0 100 50 0 % Sand 0.063 – 2 mm 0 100 Subdivisions of sandy textural classes VFS Very fine sand FS Medium sand Fine sand 0.2 – 0.63 mm S MS Medium sand CS Coarse sand US Sand, unsorted Coarse 50 50 sand LVFS Loamy very fine sand LS LFS Loamy fine sand Very coarse + coarse sand 0.63 – 2 mmSand LCS Loamy coarse sand unsorted FSL Fine sandy loam SL Medium CSL Coarse sandy loam Fine sand sand very fine sand 0 100 100 50 0 Very fine + fine sand 0.063 – 0.2 mm
Source: According to FAO (1990)
742 28 Guidelines for soil description
TABLE 25 Key to the soil textural classes ~% clay 1 Not possible to roll a wire of about 7 mm in diameter (about the diameter of a pencil) 1.1 not dirty, not floury, no fine material in the finger rills: sand S < 5 • if grain sizes are mixed: unsorted sand US < 5 • if most grains are very coarse (> 0.6 mm): very coarse and coarse sand CS < 5 • if most grains are of medium size (0.2–0.6 mm): medium sand MS < 5 • if most grains are of fine size (< 0.2 mm) but still grainy: fine sand FS < 5 • if most grains are of very fine size (< 0.12 mm), tending very fine sand VFS < 5 to be floury: 1.2 not floury, grainy, scarcely fine material in the finger rills, loamy sand LS < 12 weakly shapeable, adheres slightly to the fingers: 1.3 similar to 1.2 but moderately floury: sandy loam SL (clay-poor) < 10 2 Possible to roll a wire of about 3–7 mm in diameter (about half the diameter of a pencil) but breaks when trying to form the wire to a ring of about 2–3 cm in diameter, moderately cohesive, adheres to the fingers 2.1 very floury and not cohesive • some grains to feel: silt loam SiL (clay-poor) < 10 • no grains to feel: silt Si < 12 2.2 moderately cohesive, adheres to the fingers, has a rough and ripped surface after squeezing between fingers and • very grainy and not sticky: sandy loam SL (clay-rich) 10–25 • moderate sand grains: loam L 8–27 • not grainy but distinctly floury and somewhat sticky: silt loam SiL (clay-rich) 10–27 2.3 rough and moderate shiny surface after squeezing sandy clay loam SCL 20–35 between fingers and is sticky and grainy to very grainy: 3 Possible to roll a wire of about 3 mm in diameter (less than half the diameter of a pencil) and to form the wire to a ring of about 2–3 cm in diameter, cohesive, sticky, gnashes between teeth, has a moderately shiny to shiny surface after squeezing between fingers 3.1 very grainy: sandy clay SC 35–55 3.2 some grains to see and to feel, gnashes between teeth • moderate plasticity, moderately shiny surfaces: clay loam CL 25–40 • high plasticity, shiny surfaces: clay C 40–60 3.3 no grains to see and to feel, does not gnash between teeth • low plasticity: silty clay loam SiCL 25–40 • high plasticity, moderately shiny surfaces: silty clay SiC 40–60 • high plasticity, shiny surfaces: heavy clay HC > 60
Note: Field texture determination may depend on clay mineralogical composition. The above key works mainly for soils having illite, chlorite and/or vermiculite composition. Smectite clays are more plastic, and kaolinitic clays are stickier. Thus, clay content can be overestimated for the former, and underestimated for the latter. Source: Adapted from Schlichting, Blume and Stahr, 1995.
9≥ 30 percent clay, < 20 percent change (relative) in clay content over 12 cm to layers immediately above and below, a silt/clay ratio of < 0.4 A nitic horizon. 9Sandy loam or finer particle size A ferralic horizon. 9A texture in the fine earth fraction of very fine sand, loamy very fine sand, or finer A cambic horizon. 9A texture in the fine earth fraction coarser than very fine sand or loamy very fine sand A Brunic qualifier. 9A texture of loamy sand or finer and ≥ 8 percent clay A argic and natric horizons.
743 Chapter 4 – Soil description 29
9A texture of sand, loamy sand, sandy loam or silt loam or a combination of them A plaggic horizon. 9A higher clay content than the underlying soil and relative differences among medium, fine and very fine sand and clay < 20 percent A irragric horizon. 9A texture of sandy clay loam, clay loam, silty clay loam or finer A takyric horizon. 9≥ 8 percent clay in the underlying layer and within 7.5 cm either doubling of the clay content if the overlying layer has less then 20 percent or 20 percent (absolute) more clay A abrupt textural change. 9An abrupt change in particle-size distribution that is not solely associated with a change in clay content resulting from pedogenesis or a relative change of ≥ 20 percent in the ratios between coarse sand, medium sand, and fine sand A lithological discontinuity. 9The required amount of organic carbon depends on the clay content, if the layer is saturated with water for ≥ 30 consecutive days in most years A organic and mineral materials. 9The required amount of organic carbon depends on the texture A aridic properties. 9The depth where an argic horizon starts depends on the texture A Alisols, Acrisols, Luvisols and Lixisols, and Alic, Acric, Luvic and Lixic qualifiers. 9An argic horizon in which the clay content does not decrease by 20 percent of more (relative) from its maximum within 150 cm A Profondic qualifier. 9An absolute clay increase of ≥ 3 percent A Hypoluvic qualifier. 9A silt/clay ratio < 0.6 A Hyperalic qualifier.
Rock fragments and artefacts The presence of rock fragments influences the nutrient status, water movement, use and management of the soil. It also reflects the origin and stage of development of the soil. Artefacts (sections on artefacts and description of artefacts [below]) are useful for identifying colluviation, human occupation, and industrial processes. Large rock and mineral fragments (> 2 mm) and artefacts are described according to abundance, size, shape, state of weathering, and nature of the fragments. The abundance class TABLE 26 limits correspond with the ones Abundance of rock fragments and artefacts, by volume for surface coarse fragments and % mineral nodules, and the 40- N None 0 percent boundary coincides with V Very few 0–2 the requirement for the skeletic F Few 2–5 C Common 5–15 phase (Table 26 and Figure 5). M Many 15–40 Where rock fragments are not A Abundant 40–80 distributed regularly within a D Dominant > 80 horizon but form a “stone line”, S Stone line any content, but concentrated at a distinct depth of a horizon this should be indicated clearly.
744 30 Guidelines for soil description
Size of rock fragments and FIGURE 5 Charts for estimating proportions of coarse fragments artefacts and mottles Table 27 indicates the classification for rock fragments and artefacts.
Note for classification purposes Important diagnostic characte- 1 % 3 % 5 % 10 % ristics derived from the amount of rock fragments are: 9< 20 percent (by volume) fine earth averaged over a depth of 15 % 2 % 25 % 30 % 75 cm or to continuous rock A Leptosols and Hyperskeletic qualifier. 9≥ 40 percent (by volume) gravel or other coarse fragments aver- 40 % 50 % 75 % 90 % aged over: ¾a depth of 100 cm or to continuous rock A Skeletic qualifier; ¾a depth of 50–100 cm A Endoskeletic qualifier; ¾a depth of 20– 50 cm A Episkeletic qualifier. Medium Coarse gravel 9≥ 20 (by volume, by weighted Sand gravel average) artefacts in the upper Fine 10 mm 100 cm A Technosols. gravel 9< 40 percent (by volume) of gravels or other coarse fragments in all layers within 100 cm or to a petroplinthic, plinthic or salic horizon A Arenosols. TABLE 27 Classification of rock fragments and artefacts Rock fragments (mm) Artefacts (mm) V Very fine artefacts < 2 F Fine gravel 2–6 F Fine artefacts 2–6 M Medium gravel 6–20 M Medium artefacts 6–20 C Coarse gravel 20–60 S Stones 60–200 C Coarse artefacts > 20 B Boulders 200–600 L Large boulders > 600 Combination of classes FM Fine and medium gravel/artefacts MC Medium and coarse gravel/artefacts CS Coarse gravel and stones SB Stones and boulders BL Boulders and large boulders
745 Chapter 4 – Soil description 31
9Fragmental materials, the TABLE 28 interstices of which are filled Classification of shape of rock fragments with organic material A F Flat A Angular Histosols. S Subrounded R Rounded Shape of rock fragments The general shape or roundness of rock fragments may be described TABLE 29 using the terms in Table 28. Classification of weathering of coarse fragments F Fresh or slightly Fragments show little or no signs of Note for classification purposes weathered weathering. W Weathered Partial weathering is indicated by 9Layers with rock fragments discoloration and loss of crystal form in of angular shape overlying or the outer parts of the fragments while the centres remain relatively fresh and underlying layers with rock the fragments have lost little of their fragments of rounded shape original strength. S Strongly weathered All but the most resistant minerals are or marked differences in size weathered, strongly discoloured and altered throughout the fragments, and shape of resistant minerals which tend to disintegrate under only between superimposed layers A moderate pressure. lithological discontinuity.
State of weathering of rock TABLE 30 fragments and artefacts Codes for primary mineral fragments The state of weathering of the QU Quartz coarse fragments is described as MI Mica per Table 29. FE Feldspar
Note for classification purposes 9A layer with rock fragments without weathering rinds overlying a layer with rock fragments with weathering rinds A lithological discontinuity.
Nature of rock fragments The nature of rock fragments is described by using the same terminology as for the rock-type description (Table 12). For primary mineral fragments, other codes can be used, e.g. as per Table 30. Fragments of individual weatherable minerals (e.g. feldspars and micas) may be smaller than 2 mm in diameter. Nevertheless, where present in appreciable quantities, such fragments should be mentioned separately in the description. For artefacts, see section on artefacts (below).
Note for classification purposes 9Rock fragments that do not have the same lithology as the underlying continuous rock A lithological discontinuity.
746 32 Guidelines for soil description
TABLE 31 Field estimation and coding of the degree of decomposition and humification of peat Attributes of dry peat Attributes of wet peat Degree of Code decomposition/ Colour Visible plant Goes between the Remnant humification tissues fingers by squeezing in the hand D1 very low white to light only ± clear not muddy brown
D2 low dark brown most brown to muddy water
Fibric D3 moderate dark brown to more than 2/3 muddy muddy D4 strong black 1/3 to 2/3 1/2 to 2/3 plant structure more visible than before D5.1 moderately 1/6 to 1/3 more or less all only heavy strong decompostable
Hemic remnants D5.2 very strong less than 1/6 no remnant Sapric mud Source: Adapted from Ad-hoc-AG-Boden, 2005
Degree of decomposition and humification of peat In most organic layers, the determination of the texture class is not possible. More valuable is an estimate of the degree of decomposition and humification of the organic material. Colour and percentage of recognizable plant tissue of dry as well as of wet organic material can be used to estimate the degree of decomposition (Table 31).
Note for classification purposes 9Histosols have more than two-thirds (by volume) recognizable plant tissues A Fibric qualifier. 9Histosols have between two-thirds and one-sixth (by volume) recognizable plant tissues A Hemic qualifier. 9Histosols have less than one-sixth (by volume) recognizable plant tissues A Sapric qualifier.
Aeromorphic organic layers on forest floors On forest floors, especially under temperate and cool climates, organic matter is commonly accumulated in more or less decomposed organic layers under terrestrial conditions. In acidic and nutrient poor mineral soils, the nutrient stock of the organic layers is of vital interest for the vegetation cover. The three major forms, raw humus, moder and mull, are described as follows: ¾ Raw humus (aeromorphic mor): usually thick (5–30 cm) organic matter accumulation that is largely unaltered owing to lack of decomposers. This kind of organic matter layer develops in extremely nutrient-poor and coarse- textured soils under vegetation that produces a litter layer that is difficult to decompose. It is usually a sequence of Oi–Oe–Oa layers over a thin A horizon, easy to separate one layer from another and being very acid with a C/N ratio of > 29.
747 Chapter 4 – Soil description 33
¾ Moder (duff mull): more decomposed than raw humus but characterized by an organic matter layer on top of the mineral soil with a diffuse boundary between the organic matter layer and A horizon. In the sequence of Oi–Oe– Oa layers, it is difficult to separate one layer from another. This develops in moderately nutrient-poor conditions, usually under a cool moist climate. It is usually acidic with a C/N ratio of 18–29. ¾ Mull: characterized by the periodic absence of organic matter accumulation on the surface owing to the rapid decomposition process and mixing of organic matter and the mineral soil material by bioturbation. It is usually slightly acid to neutral with a C/N ratio of 10–18.
SOIL COLOUR (MATRIX) Soil colour reflects the composition as well as the past and present oxidation- reduction conditions of the soil. It is generally determined by coatings of very fine particles of humified organic matter (dark), iron oxides (yellow, brown, orange and red), manganese oxides (black) and others, or it may be due to the colour of the parent rock. The colour of the soil matrix l of each horizon should be recorded in the moist condition (or both dry and moist conditions where possible) using the notations for hue, value and chroma as given in the Munsell Soil Color Charts (Munsell, 1975). Hue is the dominant spectral colour (red, yellow, green, blue or violet), value is the lightness or darkness of colour ranging from 1 (dark) to 8 (light), and chroma is the purity or strength of colour ranging from 1 (pale) to 8 (bright). Where there is no dominant soil matrix colour, the horizon is described as mottled and two or more colours are given. In addition to the colour notations, the standard Munsell colour names may be given. For routine descriptions, soil colours should be determined out of direct sunlight and by matching a broken ped with the colour chip of the Munsell Soil Color Charts. For special purposes, such as for soil classification, additional colours from crushed or rubbed material may be required. The occurrence of contrasting colours related to the structural organization of the soil, such as ped surfaces, may be noted. Where possible, soil colour should be determined under uniform conditions. Early morning and late evening readings are not accurate. Moreover, the determination of colour by the same or different individuals has often proved to be inconsistent. Because soil colour is significant with respect to various soil properties, including organic matter contents, coatings and state of oxidation or reduction, and for soil classification, cross-checks are recommended and should be established on a routine basis.
Note for classification purposes Intermediate colours should be recorded where desirable for the distinction between two soil horizons and for purposes of classification and interpretation of the soil profile. Intermediate hues (important for qualifiers, such as Chromic
748 34 Guidelines for soil description
or Rhodic, and for diagnostic horizons, such as cambic) that may be used are: 3.5, 4, 6, 6.5, 8.5 and 9 YR. For example, when 3.5 YR is noted, it means that the intermediate hue is closer to 2.5 YR than 5 YR; 4 YR means closer to 5 YR, and so on. If values and chromas are near diagnostic limits, rounded-off figures should not be used, but accurate recordings should be made by using intermediate values, or by adding a + or a -. Important diagnostic hues, values and chromas are: 9Abrupt changes in colour not resulting from pedogenesis A lithological discontinuity. 9Redder hue, higher value or higher chroma than the underlying or an overlying layer A cambic horizon. 9Hue redder than 10 YR or chroma ≥ 5 (moist) A ferralic properties, Hypoferralic and Rubic qualifier. 9Hue 7.5 YR or yellower and value ≥ 4 (moist) and chroma ≥ 5 (moist) A Xanthic qualifier. 9Hue redder than 7.5 YR or both hue 7.5 YR and chroma > 4 (moist) A Chromic qualifier. 9Hue redder than 5 YR, value < 3.5 (moist) A Rhodic qualifier. 9Hue 5 YR or redder, or hue 7.5 YR and value ≤ 5 and chroma ≤ 5, or hue 7.5 YR and value ≤ 5 and chroma 5 or 6, or hue 10 YR or neutral and value and chroma ≤ 2, or 10 YR 3/1 (all moist) A spodic horizon. 9Hue 7.5 YR or yellower or GY, B or BG; value ≤ 4 (moist); chroma ≤ 2 (moist) A puddled layer (anthraquic horizon). 9Hue N1 to N8 or 2.5 Y, 5 Y, 5 G or 5 B A reductimorphic colours of the gleyic colour pattern. 9Hue 5 Y, GY or G A gyttja (limnic material). 9Chroma < 2.0 (moist) and value < 2.0 (moist) and < 3.0 (dry) A voronic horizon. 9Chroma ≤ 2 (moist) A Chernozem. 9Chroma ≤3 (moist) and value ≤ 3 (moist) and ≤ 5 (dry) A mollic and umbric horizon. 9Value and chroma ≤ 3 (moist) A hortic horizon. 9Value ≤ 4 (moist) and ≤ 5 (dry) and chroma ≤ 2 (moist) A plaggic horizon. 9Value > 2 (moist) or chroma > 2 (moist) A fulvic horizon. 9Value ≤ 2 (moist) and chroma ≤ 2 (moist) A melanic horizon. 9Values 4 to 8 and chroma 4 or less (moist) and values 5–8 and chromas 2–3 (dry) A albic horizon. 9Lower value or chroma than the overlying horizon A sombric horizon. 9Value ≥ 3 (moist) and ≥ 4.5 (dry) and chroma ≥ 2 (moist) A aridic properties. 9Value ≤ 4 (moist) A coprogenous earth or sedimentary peat (limnic material). 9Value 3, 4 or 5 (moist) A diatomaceous earth (limnic material). 9Value ≥ 5 (moist) A marl (limnic material). 9Value ≤ 3.5 (moist) and chroma ≤ 1.5 (moist) A Pellic qualifier. 9Value ≥ 5.5 (dry) A Hyperochric qualifier.
749 Chapter 4 – Soil description 35
MOTTLING Mottles are spots or blotches of different colours or shades of colour interspersed with the dominant colour of the soil. They indicate that the soil has been subject to alternate wetting (reducing) and dry (oxidizing) conditions. Mottling of the soil matrix or groundmass is described in terms of abundance, size, contrast, boundary and colour. In addition, the shape, position or any other feature may be recorded.
Note for classification purposes 9Mottles of oxides in the form of coatings or in platy, polygonal or reticulate patterns are diagnostic for the anthraquic (plough pan), hydragric, ferric, plinthic and petroplinthic horizons and for the gleyic colour pattern. 9Mottles of oxides in the form of concretions or nodules are diagnostic for the hydragric, ferric, plinthic, petroplinthic and, pisoplinthic horizons and for the stagnic colour pattern. 9Redox depleted zones in macropores with a value ≥ 4 and a chroma ≤ 2 are diagnostic for the hydragric horizon. 9Mottles or coatings of jarosite or schwertmannite are diagnostic for the thionic horizon and the Aceric qualifier. 9Mottles in the form of yellow concentrations are diagnostic for the thionic horizon.
Colour of mottles It is usually sufficient to describe the colour of the mottles in general terms, corresponding to the Munsell Soil Color Charts.
Abundance of mottles The abundance of mottles is described in terms of classes TABLE 32 indicating the percentage of the Classification of the abundance of mottles exposed surface that the mottles % N None 0 occupy (Table 32). The class limits V Very few 0–2 correspond to those of mineral F Few 2–5 nodules. When the abundance C Common 5–15 of mottles does not allow the M Many 15–40 distinction of a single predominant A Abundant > 40 matrix or groundmass colour, the predominant colours should be determined and entered as soil TABLE 33 Classification of the size of mottles matrix colours. mm V Very fine < 2 Size of mottles F Fine 2–6 Table 33 lists the classes used to M Medium 6–20 indicate the approximate diameters A Coarse > 20
750 36 Guidelines for soil description
TABLE 34 Classification of the contrast of mottles of individual mottles. They F Faint The mottles are evident only on close examina- correspond to the size classes of tion. Soil colours in both the matrix and mottles mineral nodules. have closely related hues, chromas and values. D Distinct Although not striking, the mottles are readily seen. The hue, chroma and value of the matrix Contrast of mottles are easily distinguished from those of the mottles. They may vary by as much as 2.5 units of The colour contrast between hue or several units in chroma or value. mottles and soil matrix can be P Prominent The mottles are conspicuous and mottling is one described as per Table 34. of the outstanding features of the horizon. Hue, chroma and value alone or in combination are at least several units apart. Boundary of mottles The boundary between mottle and TABLE 35 Classification of boundary between mottle and matrix matrix is described as the thickness mm of the zone within which the S Sharp < 0.5 colour transition can be located C Clear 0.5–2 without being in either the mottle D Diffuse > 2 or matrix (Table 35).
SOIL REDOX POTENTIAL AND REDUCING CONDITIONS Determination of redox potential by field method Soil redox potential is an important physico-chemical parameter used to characterize soil aeration status and availability of some nutrients (Table 36). The redox potential is also used in the WRB classification to classify redoximorphic soils. To measure redox potential (DIN/ISO Draft, DVWK, 1995), drive a hole into the soil using a rigid rod (stainless steel, 20–100 cm long, with a diameter that is 2 mm greater than the redox electrodes) to a depth about 1–2 cm less than the desired depth to be measured. Immediately clean the platinum surface of the redox electrode with sandpaper and insert the electrode about 1 cm deeper than the prepared hole. At least two electrodes should be installed for each depth
TABLE 36 Redoximorphic soil characteristics and their relation to rH values and soil processes
Redoximorphic characteristics rH values and status Processes No redoximorphic characteristics at permanently > 35 strongly aerated permanently high potentials - < 33 NO3 reduction Black Mn concretions temporary < 29 MnII formation Fe mottles and/or brown Fe concretions, in temporary < 20 FeII formation* wet conditions Blue-green to grey colour; Fe2+ ions always permanently 13–19 formation of FeII/FeIII oxides (green rust)* present Black colour due to metal sulphides, permanently < 13 sulphide formation flammable methane present permanently < 10 methane formation * For field test, see section on reducing conditions (below).
751 Chapter 4 – Soil description 37
being measured. After at least 30 minutes, measure the redox potential with a millivoltmeter against a reference electrode (e.g. Ag/AgCl in KCl of the glass electrode of pH measurements, installed in a small hole on the topsoil that has been filled with 1-M KCl solution). For dry topsoil, a salt bridge (plastic tube 2 cm in diameter and with open ends, filled with 0.5 percent (M/M) agar in KCl solution) should be installed in a hole beside and at the depth of the platinum electrodes. In this tube, the reference electrode should be installed. The measured voltage (Em) is related to the voltage of the standard hydrogen electrode by adding the potential of the reference electrode (e.g. +244 millivolt at 10 °C of Ag/AgCl in 1 M KCl, +287 of Calomel electrode). For interpretation, the results should be transformed to rH values using the formula: rH = 2pH + 2Eh/59 (Eh in mV at 25 °C). Note the rH value on the description sheet.
Reducing conditions Reductimorphic properties of the soil matrix reflect permanently wet or at least reduced conditions (Table 37). They are expressed by neutral (white to black: Munsell N1 to N) or bluish to greenish colours (Munsell 2.5 Y, 5 Y, 5 G, 5 B). The colour pattern will often change by aeration in minutes to days owing to oxidation processes. The presence of FeII ions can be tested by spraying the freshly exposed soil surface with a 0.2-percent (M/V) _,_ dipyridyl solution in 10-percent (V/V) acetic acid solution. The test yields a striking reddish-orange colour in the presence of Fe2+ ions but may not give the strong red colour in soil materials with a neutral or alkaline soil reaction. Care is necessary as the chemical is slightly toxic.
Note for classification purposes 9An rH value of < 20 is diagnostic for reducing conditions in Gleysols, Planosols and Stagnosols, and stagnic and gleyic lower level units of other RSGs. Gaseous emissions (methane, carbon dioxide, etc.) are diagnostic for the Reductic qualifier.
TABLE 37 Reductimorphic colour pattern and occurrence of Fe compounds Colour Munsell colour Formula Mineral Greyish green, light blue 5–GY–5–B2–3/1–3 FeII/FeIII Fe-mix compounds (blue-green rust)
II White, after oxidation brown N7–8 A 10 YR4/5 Fe CO3 siderite II White, after oxidation blue N7–8 A 5–B Fe 3(PO4)2 · 8 H2O vivianite
Bluish black FeS, FeS2 5–10–B1–2/1–3 Fe sulphides (with 10% HCl; H2S- smell) (or Fe3S4) White, after oxidation white N8 A N8 - - Complete loss of Fe compounds Source: Schlichting et al., 1995
752 38 Guidelines for soil description
TABLE 38 CARBONATES Classification of carbonate reaction in the soil matrix Content % N 0 Non-calcareous No detectable visible or Carbonates in soils are either audible effervescence. residues of the parent material SL 5 0–2 Slightly calcareous Audible effervescence but not visible. or the result of neo-formation MO 5 2–10 Moderately calcareous Visible effervescence. (secondary carbonates). The latter ST 5 10–25 Strongly calcareous Strong visible are concentrated mainly in the form effervescence. Bubbles form a low foam. of soft powdery lime, coatings EX 5 > 25 Extremely calcareous Extremely strong on peds, concretions, surface or reaction. Thick foam forms quickly. subsoil crusts, or hard banks. The presence of calcium carbonate
(CaCO3) is established by adding TABLE 39 some drops of 10-percent HCl to Classification of forms of secondary carbonates the soil. The degree of effervescence SC soft concretions of carbon dioxide gas is indicative HC hard concretions HHC hard hollow concretions for the amount of calcium D disperse powdery lime carbonate present. In many soils, it PM pseudomycelia* (carbonate infillings in pores, resembling is difficult to distinguish in the field mycelia) between primary and secondary M marl layer HL hard cemented layer or layers of carbonates (less than carbonates. Classes for the reaction 10 cm thick) of carbonates in the soil matrix are * Pseudomycelia carbonates are not regarded as “secondary defined as per Table 38. carbonates” if they migrate seasonally and have no permanent depth. The reaction to acid depends upon soil texture and is usually more vigorous in sandy material than in fine-textured material with the same carbonate content. Other materials, such as roots, may also give an audible reaction. Dolomite commonly reacts more slowly and less vigorously than calcite. Secondary carbonates should be tested separately; they normally react much more intensely with HCl.
Forms The forms of secondary carbonates in soils are diverse and are considered to be informative for diagnostics of soil genesis. Soft carbonate concentrations are considered to be illuvial, and hard concretions are generally believed to be of hydrogenic nature. The forms of secondary carbonates should be indicated as per Table 39.
Note for classification purposes Important carbonate contents for classification are: 9≥ 2 percent calcium carbonate equivalent A calcaric material. 9≥ 15 percent calcium carbonate equivalent in the fine earth, at least partly secondary A calcic horizon. 9Indurated layer with calcium carbonate, at least partly secondary A petrocalcic horizon.
753 Chapter 4 – Soil description 39
TABLE 40 Classification of gypsum content %
N 0 Non-gypsiric EC = < 1.8 dS m-1 in 10 g soil/25 ml H2O,
EC = < 0.18 dS m-1 in 10 g soil/250 ml H2O
SL 5 0–5 Slightly gypsiric EC = < 1.8 dS m-1 in 10 g soil/250 ml H2O
MO 5 5–15 Moderately gypsiric EC = > 1.8 dS m-1 in 10 g soil/250 ml H2O
ST 5 15–60 Strongly gypsiric higher amounts may be differentiated by abundance of H2O-soluble pseudomycelia/crystals and soil colour EX 5 > 60 Extremely gypsiric
915–25 percent calcium carbonate equivalent in the fine earth, at least partly secondary A Hypocalcic qualifier. 9≥ 50 percent calcium carbonate equivalent in the fine earth, at least partly secondary A Hypercalcic qualifier. 9Where a soil has a calcic horizon starting 50–10 cm from the soil surface, it is only a Calcisol if the soil matrix between 50 cm from the soil surface and the calcic horizon is calcareous throughout. 9Calcisols and Gypsisols can only have an argic horizon where the argic horizon is permeated with calcium carbonate (Calcisols) or calcium carbonate or gypsum (Gypsisols).
GYPSUM Content of gypsum
Gypsum (CaSO4·2H2O) may be found in the form of residues of gypsiric parent material or new formed features. The latter are pseudomycelia, coarse-sized crystals (individualized, as nests, beards or coatings, or as elongated groupings of fibrous crystals) or loose to compact powdery accumulations. The latter form gives the gypsic horizon a massive structure and a sandy texture. Where more readily soluble salts are absent, gypsum can be estimated in the field by measurements of electrical conductivity (EC in dS m-1) in soil suspensions of different soil–water relations (Table 40) after 30 minutes (in the case of fine- grained gypsum).
Forms of secondary gypsum The forms of secondary gypsum in soils are diverse and are considered to be informative for diagnostics of soil genesis. The forms of secondary carbonates should be indicated as per Table 41. TABLE 41 Classification of forms of secondary gypsum Note for classification purposes SC soft concretions Important contents of gypsum for D disperse powdery gypsum G “gazha” (clayey water-saturated layer with high gypsum classification are: content) 9≥ 5 percent (by volume) gypsum HL hard cemented layer or layers of gypsum (less than 10 cm A gypsiric material. thick)
754 40 Guidelines for soil description
9≥ 5 percent (by mass) gypsum
TABLE 42 and ≥ 1 percent (by volume) Classification of salt content of soil secondary gypsum A gypsic -1 EC2.5 = dS m (25 ºC) horizon. N (nearly)Not salty < 0.75 9Indurated layer with ≥ SL Slightly salty 0.75–2 5 percent (by mass) gypsum MO Moderately salty 2–4 ST Strongly salty 4–8 and ≥ 1 percent (by volume) VST Very strongly salty 8–15 secondary gypsum A EX Extremely salty > 15 petrogypsic horizon. Source: DVWK, 1995. 915–25 percent (by mass) gypsum and ≥ 1 percent (by volume) secondary gypsum A Hypogypsic qualifier. 9≥ 50 percent (by mass) gypsum and ≥ 1 percent (by volume) secondary gypsum A Hypergypsic qualifier. 9Gypsisols can only have an argic horizon if the argic horizon is permeated with calcium carbonate or gypsum.
READILY SOLUBLE SALTS Coastal or desert soils can be especially enriched with water-soluble salts or salts
more soluble than gypsum (CaSO4·2H2O; log Ks = -4.85 at 25 °C). The salt content of the soil can be estimated roughly from an EC (in dS m-1 = mS cm-1) measured in a saturated soil paste or a more diluted suspension of soil in water (Richards, 1954).
Conventionally, EC is measured in the laboratory in the saturation extract (ECSE). Most classification values and data about salt sensitivity of crops refer to ECSE. An easier and more comfortable method of determining EC in the field is to
use a 20 g soil/50 ml H2O (aqua dest) suspension (EC2.5) and to calculate ECSE depending on the texture and content of organic matter (Table 42).
Procedure Use a transparent plastic cup with marks for 8 cm3 soil (~ 10 g) and 25 ml water and mix carefully with a plastic stick. The EC is measured with a field conductometer after 30 minutes in the clear solution. Use water with an EC < 0.01 dS m-1.
The salt content (NaCl equivalent) can be estimated from EC2.5 by: -1 salt [%] = EC2.5 [mS cm ] · 0.067 · 2.5. The EC2.5 can be converted to ECSE depending on the texture and content of humus according to the formula below and Table 43.
Note for classification purposes -1 9Threshold values of ≥ 8 and ≥ 15 dS m (ECSE, 25 °C) A salic horizon. -1 9≥ 4 dS m (ECSE, 25°C) in at least some layer within 100 cm A Hyposalic qualifier.
755 Chapter 4 – Soil description 41
TABLE 43 Dependency of water content of saturation extract on texture and content of humus for mineral soils and on decomposition for peat soils
Textural class Water content of saturation extract WCSE in g/100 g Mineral soils Content of humus < 0.5% 0.5–1% 1–2% 2–4% 4–8% 8–15% Gravel, CS 5 6 8 13 21 35 MS 8 9 11 16 24 38 FS 10 11 13 18 26 40
LS, SL < 10% clay 14 15 17 22 30 45
SiL < 10% clay 17 18 20 25 34 49 Si 19 20 22 27 36 51
SL 10–20% clay 22 23 26 31 39 55 L 252629344258
SiL 10–27% clay 28 29 32 37 46 62 SCL 32 33 36 41 50 67 CL, SiCL 44 46 48 53 63 80 SC 51 53 55 60 70 88
SiC, C 40–60% clay 63 65 68 73 83 102
HC > 60% clay 105 107 110 116 126 147 Peat soils Decomposition stage (see section 3.3.3) D1 fibric D2 low D3 moderate D4 strong D5 sapric 80 120 170 240 300 Source: Adapted from DVWK (1995), recalculated to FAO textural classes.
-1 9≥ 30 dS m (ECSE, 25°C) in at least some layer within 100 cm A Hypersalic qualifier.
FIELD SOIL PH Soil pH expresses the activity of the hydrogen ions in the soil solution. It affects the availability of mineral nutrients to plants as well as many soil processes. When the pH is measured in the field, the method used should be indicated on the field data sheet. The field soil pH should not be a substitute for a laboratory determination. Field soil pH measurements should be correlated with laboratory determinations where possible. In the field, pH is either estimated using indicator papers, indicator liquids (e.g. Hellige), or measured with a portable pH meter in a soil suspension (1 part soil and
2.5 parts 1 M KCl or 0.1 M CaCl2 solution). After shaking the solution and waiting for 15 minutes, the pH value can be read. For the measurement, use a transparent 50- ml plastic cup with marks for 8 cm3 soil (~ 10 g) and 25 ml solution. TABLE 44 Classification of pH value
Note for classification purposes pHCaCl of < 5.1, if > 15% OM is an indication for a Dystric 2 qualifier (= base saturation As the pH value in many soils < 4.6, if 4–15% OM <50%), otherwise Eutric < 4.2, if < 4% OM A correlates with the base saturation, qualifier it may be used in the field for < 3.6, if > 15% OM is an indication for a base saturation of less than 10% preliminary classification purposes < 3.4, if 4–15% OM and for a high Al saturation < 3.2, if < 4% OM A (Table 44). However, proof in the Hyperalic qualifier laboratory is necessary. Source: Adapted from Schlichting, Blume and Stahr, 1995.
756 42 Guidelines for soil description
SOIL ODOUR TABLE 45 Classification of soil odour Record the presence of any strong Odour – kind Criteria smell (Table 45), by horizon. No N None No odour detected entry implies no odour. P Petrochemical Presence of gaseous or liquid gasoline, oil, creosote, etc. ANDIC CHARACTERISTICS AND S Sulphurous Presence of H2S (hydrogen sulphide; “rotten eggs”); commonly associated with strongly VOLCANIC GLASSES reduced soil containing sulphur compounds. Soils formed from young volcanic materials often have andic properties: a bulk density of 0.9 kg dm-3 or less, and a smeary consistence (owing to higher contents of allophane and/or ferrihydrite). Surface horizons with andic characteristics are normally black because of high humus contents. Andic characteristics may be
identified in the field using the pHNaF field test developed by Fieldes and Perrott (1966). A pHNaF of more than 9.5 indicates the presence of abundant allophanic products and/or organo-aluminium complexes. The method depends on active aluminium sorbing fluoride ions with subsequent release of OH+ ions. The test is indicative for most layers with andic properties, except for those very rich in organic matter. However, the same reaction occurs in spodic horizons and in certain acid clayey soils that are rich in aluminium-interlayered clay minerals; soils with free carbonates also react. Before applying a field NaF test, it is important to check soil pH (the test is not suitable for alkaline soils) and the presence of free carbonates (using HCl field test).
Procedure Place a small amount of soil material on a filter paper previously soaked in phenolphthalein and add some drops of 1 M NaF (adjusted to pH 7.5). A positive reaction is indicated by a fast change to an intense red colour. Alternatively, measure the pH of a suspension of 1 g soil in 50 ml 1 M NaF (adjusted to pH 7.5) after 2 minutes. If the pH is more than 9.5, it is a positive indication. Note in the description sheet the sign of a + or a -. In addition, soil material with andic characteristics may exhibit thixotropy; the soil material changes under pressure or by rubbing from a plastic solid into a liquefied stage and back into the solid condition.
Note for classification purposes 9Positive field test for allophanic products and/or organo-aluminium complexes A andic properties. 9Thixotropy A Thixotropic qualifier. In many young volcanic materials, volcanic glasses, glassy aggregates and other glass-coated primary minerals occur. Coarser fractions may be checked by a ×10 hand-lens; finer fractions may be checked by microscope.
757 Chapter 4 – Soil description 43
Note for classification purposes 9≥ 5 percent (by grain count) volcanic glass, glassy aggregates and other glass- coated primary minerals, in the fraction 0.05–2 mm, or in the fraction 0.02– 0.25 mm A vitric properties. 9≥ 30 percent (by grain count) volcanic glass, glass-coated primary minerals, glassy materials, and glassy aggregates in the 0.02–2 mm particle-size fraction A tephric material.
ORGANIC MATTER CONTENT Organic matter refers to all decomposed, partly decomposed and undecomposed organic materials of plant and animal origin. It is generally synonymous with humus although the latter is more commonly used when referring to the well- decomposed organic matter called humic substances. The content of organic matter of mineral horizons can be estimated from the Munsell colour of a dry and/or moist soil, taking the textural class into account (Table 46). This estimation is based on the assumption that the soil colour (value) is due to a mixture of dark coloured organic substances and light coloured minerals. This estimate does not work very well in strongly coloured subsoils. It tends to overestimate organic matter content in soils of dry regions, and to underestimate the organic matter content in some tropical soils. Therefore, the organic matter values should always be locally checked as they only provide a rough estimate.
TABLE 46 Estimation of organic matter content based on Munsell soil colour
Colour Munsell Moist soil Dry soil value S LS, SL, L SiL, Si, SiCL, CL, S LS, SL, L SiL, Si, SiCL, CL, SCL, SC, SiC, C SCL, SC, SiC, C (%) Light grey 7 < 0.3 < 0.5 < 0.6 Light grey 6.5 0.3–0.6 0.5–0.8 0.6–1.2 Grey 6 0.6–1 0.8–1.2 1.2–2 Grey 5.5 < 0.3 1–1.5 1.2–2 2–3 Grey 5 < 0.3 < 0.4 0.3–0.6 1.5–2 2–4 3–4 Dark grey 4.5 0.3–0.6 0.4–0.6 0.6–0.9 2–3 4–6 4–6 Dark grey 4 0.6–0.9 0.6–1 0.9–1.5 3–5 6–9 6–9 Black grey 3.5 0.9–1.5 1–2 1.5–3 5–8 9–15 9–15 Black grey 3 1.5–3 2–4 3–5 8–12 > 15 > 15 Black 2.5 3–6 > 4 > 5 > 12 Black 2 > 6 Note: If chroma is 3.5–6, add 0.5 to value; if chroma is > 6, add 1.0 to value. Source: Adapted from Schlichting, Blume and Stahr, 1995.
758 44 Guidelines for soil description
Note for classification purposes 9If saturated with water for ≥ 30 consecutive days in most years (unless drained): ≥ [12 + (clay percentage of the mineral fraction × 0.1)]% organic carbon or ≥ 18 percent organic carbon, else ≥ 20 percent organic carbon A organic material. 9Organic material saturated with water for ≥ 30 consecutive days in most years (unless drained) A histic horizon. 9Organic material saturated with water for < 30 consecutive days in most years A folic horizon. 9Weighted average of ≥ 6 percent organic carbon, and ≥ 4 percent organic carbon in all parts A fulvic and melanic horizon. 9Organic carbon content of ≥ 0.6 percent A mollic and umbric horizon. 9Organic carbon content of ≥ 1.5 percent A voronic horizon. (Note: the ratio of organic carbon to organic matter is about 1:1.7–2.) Write the range or average value in the description sheet.
ORGANIZATION OF SOIL CONSTITUENTS This section describes the primary physical organization of arrangement of the soil constituents, together with the consistence of the constituents. Primary organization is considered as being the overall arrangement of the soil mass without concentrations, reorientations and biological additions. It will not always be possible to make clear distinctions between primary and secondary elements of the organization. Voids (pores), which relate to the structural organization of soil, are described in a later section.
Soil structure Soil structure refers to the natural organization of soil particles into discrete soil units (aggregates or peds) that result from pedogenic processes. The aggregates are separated from each other by pores or voids. It is preferred to describe the structure when the soil is dry or slightly moist. In moist or wet conditions, it is advisable to leave the description of structure to a later time when the soil has dried out. For the description of soil structure, a large lump of the soil should be taken from the profile, from various parts of the horizon if necessary, rather than observing the soil structure in situ. Soil structure is described in terms of grade, size and type of aggregates. Where a soil horizon contains aggregates of more than one grade, size or type, the different kinds of aggregates should be described separately and their relationship indicated.
Grade In describing the grade or development of the structure, the first division is into apedal soils (lacking soil structure) and pedal soils (showing soil structure). In apedal or structureless soil, no aggregates are observable in place and there is no definite arrangement of natural surfaces of weakness. Structureless soils are subdivided into single grain and massive (see below). Single-grain soil material
759 Chapter 4 – Soil description 45
has a loose, soft or very friable consistence and consists on rupture of more than 50 percent discrete mineral particles. Massive soil material normally has a stronger consistence and is more coherent on rupture. Massive soil material may be further defined by consistence (below) and porosity (below). Grades of structure of pedal soil materials are defined as per Table 47.
TABLE 47 Classification of structure of pedal soil materials WE Weak Aggregates are barely observable in place and there is only a weak arrangement of natural surfaces of weakness. When gently disturbed, the soil material breaks into a mixture of few entire aggregates, many broken aggregates, and much material without aggregate faces. Aggregate surfaces differ in some way from the aggregate interior. MO Moderate Aggregates are observable in place and there is a distinct arrangement of natural surfaces of weakness. When disturbed, the soil material breaks into a mixture of many entire aggregates, some broken aggregates, and little material without aggregates faces. Aggregates surfaces generally show distinct differences with the aggregates interiors. ST Strong Aggregates are clearly observable in place and there is a prominent arrangement of natural surfaces of weakness. When disturbed, the soil material separates mainly into entire aggregates. Aggregates surfaces generally differ markedly from aggregate interiors. Combined classes may be constructed as follows: WM Weak to moderate MS Moderate to strong
FIGURE 6 Soil structure types and their formation
Pedogenic ped formation? No Caronates Yes Single Massive Layered Gypsum grain (coherent) (coherent) Formed by cementation from precipitates of Humus Iron Silica Formed by assemble Formed by separation Formed by fragmentation (biotic) (abiotic) or compaction
Granular Worm- Blocky Blocky Prismatic Columnar Platy Crumbly Lumpy Clody casts subangular angular
760 46 Guidelines for soil description
TABLE 48 Classification of types of soil structure Blocky Blocks or polyhedrons, nearly equidimensional, having flat or slightly rounded surfaces that are casts of the faces of the surrounding aggregates. Subdivision is recommended into angular, with faces intersecting at relatively sharp angles, and subangular blocky faces intersecting at rounded angles. Granular Spheroids or polyhedrons, having curved or irregular surfaces that are not casts of the faces of surrounding aggregates. Platy Flat with vertical dimensions limited; generally oriented on a horizontal plane and usually overlapping. Prismatic the dimensions are limited in the horizontal and extended along the vertical plane; vertical faces well defined; having flat or slightly rounded surfaces that are casts of the faces of the surrounding aggregates. Faces normally intersect at relatively sharp angles. Prismatic structures with rounded caps are distinguished as Columnar. Rock structure Rock structure includes fine stratification in unconsolidated sediment, and pseudomorphs of weathered minerals retaining their positions relative to each other and to unweathered minerals in saprolite from consolidated rocks. Wedge-shaped Elliptical, interlocking lenses that terminate in sharp angles, bounded by slickensides; not limited to vertic materials. Crumbs, lumps and clods Mainly created by artificial disturbance, e.g. tillage.
TABLE 49 Type Codes for types of soil structure The basic natural types of structure RS Rock structure (Figure 6) are defined as per SS Stratified structure SG Single grain Table 48. MA Massive Where required, special cases PM Porous massive or combinations of structures BL Blocky AB Angular blocky may be distinguished, which are AP Angular blocky (parallelepiped) subdivisions of the basic structures. AS Angular and subangular blocky The recommended codes are given AW Angular blocky (wedge-shaped) SA Subangular and angular blocky in Table 49. SB Subangular blocky SN Nutty subangular blocky Size PR Prismatic PS Subangular prismatic Size classes vary with the structure WE Wedge-shaped type. For prismatic, columnar and CO Columnar platy structures, the size classes GR Granular WC Worm casts refer to the measurements of the PL Platy smallest dimension of the aggregate CL Cloddy (Table 50). CR Crumbly LU Lumpy Combined classes may be constructed as per Table 51. Where a second structure is present, its relation to the first structure is described. The first and second structures may both be present (e.g. columnar and prismatic structures). The primary structure may break down into a secondary structure (e.g. prismatic breaking into angular blocky). The first structure may merge into the second structure (e.g. platy merging into prismatic). These can be indicated as per Table 52.
761 Chapter 4 – Soil description 47
TABLE 50 Size classes for soil structure types Granular/platy Prismatic/columnar/wedge- Blocky/crumbly/lumpy/ shaped cloddy (mm) (mm) (mm) VF Very fine/thin < 1 < 10 < 5 FI Fine/thin 1–2 10–20 5–10 ME Medium 2–5 20–50 10–20 CO Coarse/thick 5–10 50–100 20–50 VC Very coarse/thick > 10 100–500 > 50 EC Extremely coarse – > 500 –
Note for classification purposes TABLE 51 9Soil structure, or absence Combined size classes for soil structure types of rock structure (the term FF Very fine and fine VM Very fine to medium “rock structure” also applies FM Fine and medium to unconsolidated sediments FC Fine to coarse in which stratification is still MC Medium and coarse visible) in half of the volume or MV Medium to very coarse more of the fine earth A cambic CV Coarse and very coarse horizon. 9Soil structure sufficiently strong TABLE 52 that the horizon is not both Combinations of soil structures massive and hard or very hard CO + PR Both structures present when dry (prisms larger than PR A AB Primary breaking to secondary structure 30 cm in diameter are included PL / PR One structure merging into the other in the meaning of massive if there is no secondary structure within the prisms) A mollic, umbric and anthric horizons. 9Granular or fine subangular blocky soil structure (and worm casts) A voronic horizon. 9Columnar or prismatic structure in some part of the horizon or a blocky structure with tongues of an eluvial horizon A natric horizon. 9Moderate to strong, angular blocky structure breaking to flat-edged or nut- shaped elements with shiny ped faces A nitic horizon. 9Wedge-shaped structural aggregates with a longitudinal axis tilted 10–60 ° from the horizontal A vertic horizon. 9Wedge-shaped aggregates A vertic properties. 9Platy structure A puddled layer (anthraquic horizon). 9Uniformly structured A irragric horizon. 9Separations between structural soil units that allow roots to enter have an average horizontal spacing of ≥ 10 cm A fragic horizon. 9Platy or massive structure A takyric horizon. 9Platy layer A yermic horizon.
762 48 Guidelines for soil description
9Strong structure finer than very coarse granular A Grumic qualifier. 9Massive and hard to very hard in the upper 20 cm of the soil A Mazic qualifier. 9A platy structure and a surface crust A Hyperochric qualifier. 9Stratification in ≥ 25 percent of the soil volume A fluvic material.
Consistence Consistence refers to the degree of cohesion or adhesion of the soil mass. It includes soil properties such as friability, plasticity, stickiness and resistance to compression. It depends greatly on the amount and type of clay, organic matter and moisture content of the soil. For reference descriptions (Status 1, Chapter 2), a recording of consistence is required for the dry, moist and wet (stickiness and plasticity) states. Where applicable, the smeariness (thixotropy) and fluidity may also be recorded. For routine descriptions, the soil consistence in the natural moisture condition of the profile may be described. Wet consistence can always be described, and moist conditions where the soil is dry, by adding water to the soil sample.
Consistence when dry The consistence when dry (Table 53) is determined by breaking an air-dried mass of soil between thumb and forefinger or in the hand.
Consistence when moist Consistence when moist (Table 54) is determined by attempting to crush a mass of moist or slightly moist soil material.
Consistence when wet: maximum stickiness and maximum plasticity Soil stickiness depends on the extent to which soil structure is destroyed and on the amount of water present. The determination of stickiness should be performed under standard conditions on a soil sample in which structure is completely destroyed and which contains enough water to express its maximum stickiness. In this way, the maximum stickiness will be determined and comparison between degrees of stickiness of various soils will be feasible. The same principle applies to soil plasticity.
TABLE 53 Consistence of soil mass when dry LO Loose Non-coherent. SO Soft Soil mass is very weakly coherent and fragile; breaks to powder or individual grains under very slight pressure. SHA Slightly hard Weakly resistant to pressure; easily broken between thumb and forefinger. HA Hard Moderately resistant to pressure; can be broken in the hands; not breakable between thumb and forefinger. VHA Very hard Very resistant to pressure; can be broken in the hands only with difficulty. EHA Extremely hard Extremely resistant to pressure; cannot be broken in the hands. Note: Additional codes, needed occasionally to distinguish between two horizons or layers, are: SSH, soft to slightly hard; SHH, slightly hard to hard; and HVH, hard to very hard.
763 Chapter 4 – Soil description 49
TABLE 54 Consistence of soil mass when moist LO Loose Non-coherent. VFR Very friable Soil material crushes under very gentle pressure, but coheres when pressed together. FR Friable Soil material crushes easily under gentle to moderate pressure between thumb and forefinger, and coheres when pressed together. FI Firm Soil material crushes under moderate pressure between thumb and forefinger, but resistance is distinctly noticeable. VFI Very firm Soil material crushes under strong pressures; barely crushable between thumb and forefinger. EFI Extremely firm Soil material crushes only under very strong pressure; cannot be crushed between thumb and forefinger.
Note: Additional codes are: VFF, very friable to friable; FRF, friable to firm; and FVF, firm to very firm.
Stickiness is the quality of TABLE 55 adhesion of the soil material to Classification of soil stickiness NST Non-sticky After release of pressure, practically no soil other objects determined by noting material adheres to thumb and finger. the adherence of soil material when SST Slightly sticky After pressure, soil material adheres to both thumb and finger but comes off it is pressed between thumb and one or the other rather cleanly. It is not finger (Table 55). appreciably stretched when the digits are separated. Plasticity is the ability of ST Sticky After pressure, soil material adheres to soil material to change shape both thumb and finger and tends to stretch somewhat and pull apart rather continuously under the influence than pulling free from either digit. of an applied stress and to retain VST Very sticky After pressure, soil material adheres strongly to both thumb and finger and the compressed shape on removal is decidedly stretched when they are of stress. Determined by rolling separated. Note: Additional codes are: SSS, slightly sticky to sticky; and SVS, sticky the soil in the hands until a wire to very sticky. about 3 mm in diameter has been formed (Table 56).
TABLE 56 Note for classification purposes Classification of soil plasticity 9Extremely hard consistence when NPL Non-plastic No wire is formable. dry A petrocalcic horizon. SPL Slightly plastic Wire formable but breaks immediately if bent into a ring; soil mass deformed by 9Surface crust with very hard very slight force. consistence when dry, and very PL Plastic Wire formable but breaks if bent into a ring; slight to moderate force required plastic and sticky consistence for deformation of the soil mass. when wet A takyric horizon. VPL Very plastic Wire formable and can be bent into a ring; moderately strong to very strong 9Air-dry clods, 5–10 cm in force required for deformation of the diameter, slake or fracture in soil mass. water within 10 minutes A Note: Additional codes are: SPP, slightly plastic to plastic; and PVP, plastic to very plastic. fragic horizon. 9Penetration resistance at field capacity of ≥ 50 kN m-1 A fragic horizon. 9Penetration resistance of ≥ 450 N cm-2 A petroplinthic horizon.
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TABLE 57 Classification of moisture status of soil Rubbing Crushing Forming (to a ball) Moistening Moisture pF* (in the hand) dusty or hard not possible, seems to be warm going very dark not lighter very dry 5 makes no dust not possible, seems to be warm going dark hardly lighter dry 4 makes no dust possible (not sand) going slightly dark obviously lighter slightly moist 3 finger moist and cool, weakly is sticky no change of colour obviously lighter moist 2 shiny free water drops of water no change of colour wet 1 free water drops of water without crushing no change of colour very wet 0 * pF (p = potential, F = free energy of water) is log hPa.
Soil-water status Soil-water status is the term used for the moisture condition of a horizon at the time the profile is described. The moisture status can be estimated in the field as per Table 57.
Note for classification purposes 9The definitions of mineral and organic materials and of the histic, folic and cryic horizons depend on the soil-water status. 9Temporarily water-saturated A Gelistagnic, Oxyaquic and Reductaquic qualifiers. 9Organic material floating on water A Floatic qualifier. 9Permanently submerged under water < 2 m A Subaquatic qualifier. 9Flooded by tidewater, but not covered at mean low tide A Tidalic qualifier. 9Artificially drained histic horizon A Drainic qualifier.
BULK DENSITY Bulk density is defined as the mass of a unit volume of dry soil (105 °C). This volume includes both solids and pores and, thus, bulk density reflects the total soil porosity. Low bulk density values (generally below 1.3 kg dm-3) generally indicate a porous soil condition. Bulk density is an important parameter for the description of soil quality and ecosystem function. High bulk density values indicate a poorer environment for root growth, reduced aeration, and undesirable changes in hydrologic function, such as reduced water infiltration. There are several methods of determining soil bulk density. One method is to obtain a known volume of soil, dry it to remove the water, and weigh the dry mass. Another uses a special coring instrument (cylindrical metal device) to obtain a sample of known volume without disturbing the natural soil structure, and then to determine the dry mass. For surface horizons, a simple method is to dig a small hole and fill it completely with a measured volume of sand. Field determinations of bulk density may be obtained by estimating the force required to push a knife into a soil horizon exposed at a field moist pit wall (Table 58).
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TABLE 58 Field estimation of bulk density for mineral soils Observation Frequent ped shape Bulk density (kg dm-3) Code Sandy, silty and loamy soils with low clay content Many pores, moist materials drop easily out of the auger; materials with granular < 0.9 vesicular pores, mineral soils with andic properties. BD1 Sample disintegrates at the instant of sampling, many pores visible on single grain, granular 0.9–1.2 the pit wall. BD1 Sample disintegrates into numerous fragments after application of weak single grain, subangular, 1.2–1.4 pressure. angular blocky BD2 Knife can be pushed into the moist soil with weak pressure, sample subangular and angular 1.4–1.6 disintegrates into few fragments, which may be further divided. blocky, prismatic, platy BD3 Knife penetrates only 1–2 cm into the moist soil, some effort required, prismatic, platy, (angular 1.6–1.8 sample disintegrates into few fragments, which cannot be subdivided blocky) BD4 further. Very large pressure necessary to force knife into the soil, no further prismatic > 1.8 disintegration of sample. BD5 Loamy soils with high clay content, clayey soils When dropped, sample disintegrates into numerous fragments, further angular blocky 1.0–1.2 disintegration of subfragments after application of weak pressure. BD1 When dropped, sample disintegrates into few fragments, further angular blocky, prismatic, 1.2–1.4 disintegration of subfragments after application of mild pressure. platy, columnar BD2 Sample remains mostly intact when dropped, further disintegration coherent, prismatic, 1.4–1.6 possible after application of large pressure. platy, (columnar, angular BD3 blocky, platy, wedge– shaped) Sample remains intact when dropped, no further disintegration after coherent (prismatic, >1.6 application of very large pressure. columnar, wedge– BD4, 5 shaped) Note: If organic matter content is > 2%, bulk density has to be reduced by 0.03 kg dm-3 for each 1% increment in organic matter content.
Note for classification purposes 9Bulk density of 0.90 kg dm-3 or less A andic properties. 9In the plough pan, a bulk FIGURE 7 density ≥20 percent (relative) Qualification of bulk density higher than that of the puddled Si SiL SiCL SiC layer A anthraquic horizon. L CL C HC SL SCL SC Root penetration is not only LS Texture classes S limited by bulk density, but also by 2.0 BD5 g cm-3 Very firm (PD5) BD4 texture. Fine-textured soils contain Firm (PD4) BD3 1.5 Intermediate (PD3) fewer pores in size and abundance BD2 Loose (PD2) Bulk densty BD1 than needed for unrestricted 1.0 Very loose (PD1) root growth. Therefore, the evaluation of bulk density has to 0 50 100 % Clay content take soil texture into account. For evaluation purposes the “packing Source: according to Ad-hoc-AG-Boden, 2005. density” (PD = BD + 0.009 ·% clay) can also be used (Figure 7).
766 52 Guidelines for soil description
TABLE 59 Field estimation of volume of solids and bulk density of peat soils Drainage conditions Solid volume Bulk density Bog Fen Peat characteristics Classes of decomposition Vol. (%) g cm-3 Code Undrained Undrained Almost swimming D1 Very low (fibric) < 3 < 0.04 SV1 Weakly drained Weakly Loose D2 Low (fibric) 3– < 5 0.04–0.07 drained SV2 Moderately drained Weakly Rather loose D3 Moderate (fibric) 5– < 8 0.07–0.11 drained SV3 Well drained Moderately Rather dense D4 Strong (hemic) 8– < 12 0.11–0.17 drained SV4 Well drained Well drained Dense D5 Very strong (sapric) ≥ 12 > 0.17 SV5 Source: Adapted from Ad-hoc-AG-Boden, 2005.
Bulk density and volume of solids of organic soils may be estimated after the decomposition stage or the extent of peat drainage. Weakly drained and weakly decomposed peat materials are characterized by a lower bulk density and a lower solid volume than well-drained and strongly decomposed peat materials (Table 59). Organic surface horizons of mineral soils may be treated like strongly decomposed peat layers.
VOIDS (POROSITY) Voids include all empty spaces in the soil. They are related to the arrangement of the primary soil constituents, rooting patterns, burrowing of animals or any other soil-forming processes, such as cracking, translocation and leaching. The term void is almost equivalent to the term pore, but the latter is often used in a more restrictive way and does not, for example, include fissures or planes. Voids are described in terms of type, size and abundance. In addition, continuity, orientation or any other feature may also be recorded.
Porosity The porosity is an indication of the total volume of voids discernible with a ×10 hand-lens measured by area and recorded as the percentage of the surface occupied by pores (Table 60).
Type TABLE 60 Classification of porosity There is a large variety in the shape % and origin of voids. It is impractical 1 Very low < 2 and usually not necessary to 2 Low 2–5 describe all different kinds of 3 Medium 5–15 voids comprehensively. Emphasis 4 High 15–40 should be given to estimating the 5 Very high > 40 continuous and elongated voids.
767 Chapter 4 – Soil description 53
TABLE 61 Classification of voids I Interstitial Controlled by the fabric, or arrangement, of the soil particles, also known as textural voids. Subdivision possible into simple packing voids, which relate to the packing of sand particles, and compound packing voids, which result from the packing of non-accommodating peds. Predominantly irregular in shape and interconnected, and hard to quantify in the field. B Vesicular Discontinuous spherical or elliptical voids (chambers) of sedimentary origin or formed by compressed air, e.g. gas bubbles in slaking crusts after heavy rainfall. Relatively unimportant in connection with plant growth. V Vughs Mostly irregular, equidimensional voids of faunal origin or resulting from tillage or disturbance of other voids. Discontinuous or interconnected. May be quantified in specific cases. C Channels Elongated voids of faunal or floral origin, mostly tubular in shape and continuous, varying strongly in diameter. When wider than a few centimetres (burrow holes), they are more adequately described under biological activity. P Planes Most planes are extra-pedal voids, related to accommodating ped surfaces or cracking patterns. They are often not persistent and vary in size, shape and quantity depending on the moisture condition of the soil. Planar voids may be recorded, describing width and frequency.
The major types of voids may be classified in a simplified way as per Table 61. In most cases, it is recommended that only the size and abundance of the channels, which are mostly continuous tubular pores, be described (Figure 8). For the other types of voids, the following size and abundance classes should serve as a guide for the construction of suitable classes for each category.
Size The diameter of the elongated or tubular voids is described as per Table 62.
Abundance The abundance of very fine and fine elongated pores as one group, TABLE 62 and of medium and coarse pores as Classification of diameter of voids another group is recorded as the mm number per unit area in a square V Very fine < 0.5 decimetre (Table 63). F Fine 0.5–2 M Medium 2–5 C Coarse 5–20 Note for classification purposes VC Very coarse 20–50 9Vesicular layer below a platy Note: Additional codes are: FM, fine and medium; FF fine and very layer or pavement with a vesicular fine; and MC, medium and coarse. layer A yermic horizon. 9Sorted soil aggregates and vesicular pores A anthraquic TABLE 63 horizon. Classification of abundance of pores < 2 mm (number) > 2 mm N None 0 0 CONCENTRATIONS V Very few 1–20 1–2 This section deals with the most F Few 20–50 2–5 common concentrations of soil C Common 50–200 5–20 materials, including secondary M Many > 200 > 20 enrichments, cementations and reorientations.
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FIGURE 8 Charts for estimating size and abundance of pores
Abundance Very few Few Common Size
Very fine (<0.5 mm)
Fine (0.5–2 mm)
Medium (2–5 mm)
1 cm
Coatings This section describes clay or mixed-clay illuviation features, coatings of other composition (such as calcium carbonate, manganese, organic or silt), reorientations (such as slickensides and pressure faces), and concentrations associated with surfaces but occurring as stains in the matrix (“hypodermic coatings”). All these features are described according to their abundance, contrast, nature, form and location.
Abundance For coatings, an estimate is made of how much of the ped or aggregate faces is covered (Table 64). Corresponding criteria should be applied when the cutanic feature is related to other surfaces (voids, and coarse fragments) or occurs as lamellae.
Contrast Table 65 shows the classification of the contrast of coatings.
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Nature TABLE 64 The nature of coatings may be Classification of abundance of coatings described as per Table 66. % N None 0 V Very few 0–2 Form F Few 2–5 For some coatings, the form C Common 5–15 may be informative for their M Many 15–40 genesis (Table 67). For example, A Abundant 40–80 manganese and iron–manganese D Dominant > 80 coatings of dendroidal form indicate their formation owing to TABLE 65 poor infiltration and periodically Classification of the contrast of coatings reductive conditions because of F Faint Surface of coating shows only little contrast in percolating water. colour, smoothness or any other property to the adjacent surface. Fine sand grains are readily apparent in the cutan. Lamellae are less than Location 2 mm thick. D Distinct Surface of coating is distinctly smoother or The location of the coatings or different in colour from the adjacent surface. Fine sand grains are enveloped in the coating clay accumulation is indicated but their outlines are still visible. Lamellae are (Table 68). For pressure faces and 2–5 mm thick. slickensides, no location is given P Prominent Surface of coatings contrasts strongly in smoothness or colour with the adjacent surfaces. because they are by definition Outlines of fine sand grains are not visible. located on pedfaces. Lamellae are more than 5 mm thick.
TABLE 66 Classification of the nature of coatings C Clay S Sesquioxides H Humus CS Clay and sesquioxides CH Clay and humus (organic matter) CC Calcium carbonate GB Gibbsite HC Hypodermic coatings (Hypodermic coatings, as used here, are field-scale features, commonly only expressed as hydromorphic features. Micromorphological hypodermic coatings include non-redox features [Bullock et al., 1985].) JA Jarosite MN Manganese SL Silica (opal) SA Sand coatings ST Silt coatings SF Shiny faces (as in nitic horizon) PF Pressure faces SI Slickensides, predominantly intersecting (Slickensides are polished and grooved ped surfaces that are produced by aggregates sliding one past another.) SP Slickensides, partly intersecting SN Slickensides, non intersecting
Source: Adapted from Schoeneberger et al, 2002.
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Note for classification purposes TABLE 67 Classification of the form of coatings 9Evidence of silica accumulation, C Continuous e.g. as coatings A petroduric CI Continuous irregular (non-uniform, heterogeneous) horizon. DI Discontinuous irregular 9Slickensides A vertic horizon DE Dendroidal and vertic properties. DC Discontinuous circular O Other 9Evidence of clay illuviation A argic and natric horizons. 9Cracked coatings on sand grains
TABLE 68 A spodic horizon. Classification of the location of coatings and clay 9Uncoated sand and silt grains A accumulation Greyic qualifier. P Pedfaces 9Clay coatings in the argic PV Vertical pedfaces horizon A Cutanic qualifier. PH Horizontal pedfaces CF Coarse fragments 9Illuviation in the form of LA Lamellae (clay bands) lamellae in the argic, natric and VO Voids spodic horizon A Lamellic BR Bridges between sand grains qualifier. NS No specific location 9Coatings that have a different colour from the matrix (section on mottling [above]). TABLE 69 Classification of the continuity of cementation/compaction Cementation and compaction B Broken The layer is less than 50 percent cemented The occurrence of cementation or or compacted, and shows a rather irregular appearance. compaction in pans or otherwise is D Discontinuous The layer is 50–90 percent cemented or described according to its nature, compacted, and in general shows a regular appearance. continuity, structure, agent and C Continuous The layer is more than 90 percent degree. cemented or compacted, and is only interrupted in places by cracks or fissures. Compacted material has a firm or stronger consistence when moist and a close packing of particles. Cemented material does TABLE 70 not slake after 1 hour of immersion Classification of the fabric of the cemented/compacted in water. layer P Platy The compacted or cemented parts are plate- like and have a horizontal or subhorizontal Continuity orientation. Table 69 indicates the classification V Vesicular The layer has large, equidimensional voids that may be filled with uncemented material. of the continuity of cementation/ P Pisolithic The layer is largely constructed from compaction. cemented spherical nodules. D Nodular The layer is largely constructed from cemented nodules or concretions of irregular Structure shape. The fabric or structure of the cemented or compacted layer may be described as per Table 70.
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Nature TABLE 71 The nature of cementation or Classification of the nature of cementation/compaction compaction is described according K Carbonates to the cementing agent or Q Silica compacting activity, as indicated in KQ Carbonates–silica Table 71. F Iron FM Iron–manganese (sesquioxides) FO Iron–organic matter Degree I Ice Table 72 indicates the classification GY Gypsum of the degree of cementation/ C Clay compaction. CS Clay–sesquioxides M Mechanical Note for classification purposes P Ploughing 9Ice overlain by organic material NK Not known A Histosols. 9Cementation by ice or readily visible ice crystals A cryic horizon. 9≥ 75 percent ice (by volume) A Glacic qualifier. 9Cementation by organic matter and aluminium A spodic horizon. 9Cemented spodic horizon A Ortsteinic qualifier. 9Iron pan that is 1–25 mm thick and is continuously cemented by a combination of organic matter, iron and/or aluminium A Placic qualifier. 9Strongly cemented or indurated A petrocalcic, duric, gypsic and plinthic horizons, Petric, Petrogleyic and Petrosalic qualifiers. 9Cementation on repeated wetting and drying A plinthic horizon. 9Roots cannot penetrate except along vertical fractures that have an average horizontal spacing of ≥ 10 cm and occupy < 20 percent (by volume) of the layer A petrocalcic, petroduric and petrogypsic horizons. 9Strongly cemented or indurated horizon consisting of clods with an average horizontal length of < 10 cm A Fractipetric and Fractiplinthic qualifiers. Natural or artificial compaction A Densic qualifier.
TABLE 72 Classification of the degree of cementation/compaction
N Non-cemented and non-compacted Neither cementation nor compaction observed (slakes in water). Y Compacted but non-cemented Compacted mass is appreciably harder or more brittle than other comparable soil mass (slakes in water). W Weakly cemented Cemented mass is brittle and hard, but can be broken in the hands. M Moderately cemented Cemented mass cannot be broken in the hands but is discontinuous (less than 90 percent of soil mass). C Cemented Cemented mass cannot be broken in the hands and is continuous (more than 90 percent of soil mass). I Indurated Cemented mass cannot be broken by body weight (75-kg standard soil scientist) (more than 90 percent of soil mass).
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TABLE 73 Mineral concentrations Classification of the abundance of mineral concentrations, Mineral concentrations cover by volume a large variety of secondary % N None 0 crystalline, microcrystalline and V Very few 0–2 amorphous concentrations of non- F Few 2–5 organic substances as infillings, C Common 2–15 soft concretions, irregular M Many 15–40 concentrations (mottles), nodules A Abundant 40–80 D Dominant > 80 of mainly pedogenetically formed materials. Gradual transitions exist with mottles (above), some
TABLE 74 of which may be considered as Classification of the kinds of mineral concentrations weak expressions of nodules. T Crystal The mineral concentrations are C Concretion A discrete body with a concentric described according to their internal structure, generally cemented. abundance, kind, size, shape, SC Soft concretion S Soft segregation Differs from the surrounding soil mass hardness, nature and colour. (or soft in colour and composition but is not accumulation) easily separated as a discrete body. Abundance (by volume) N Nodule Discrete body without an internal organization. Table 73 describes the classification IP Pore infillings Including pseudomycelium of of the abundance of mineral carbonates or opal. concentrations. IC Crack infillings R Residual rock Discrete impregnated body still fragment showing rock structure. Kind O Other Table 74 describes the classification of the kinds of mineral concen- trations. TABLE 75 Classification of the size and shape of mineral concentrations Size and shape Size (mm) Shape Table 75 describes the classification V Very fine < 2 R Rounded (spherical) of the size and shape of mineral F Fine 2–6 E Elongated concentrations. M Medium 6–20 F Flat C Coarse > 20 I Irregular A Angular Hardness Table 76 describes the classification of the hardness of mineral concen- TABLE 76 trations. Classification of the hardness of mineral concentrations H Hard Cannot be broken in the fingers. Nature S Soft Can be broken between forefinger and thumb nail Mineral concentrations are described B Both hard and soft. according to the composition or impregnating substance. Table 77 provides some examples.
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Colour TABLE 77 The general colour names given in Examples of the nature of mineral concentrations Table 78 are usually sufficient to K Carbonates (calcareous) KQ Carbonates–silica describe the colour of the nodules C Clay (argillaceous) (similar to mottles) or of artefacts. CS Clay–sesquioxides GY Gypsum (gypsiferous) SA Salt (saline) Note for classification purposes GB Gibbsite 9≥ 10 percent (by volume) of JA Jarosite weakly cemented to indurated, S Sulphur (sulphurous) Q Silica (siliceous) silica-enriched nodules F Iron (ferruginous) (durinodes) A duric horizon. FM Iron–manganese (sesquioxides) 9Reddish to blackish nodules of M Manganese (manganiferous) NK Not known which at least the exteriors are at least weakly cemented or indurated A ferric horizon. TABLE 78 9Firm to weakly cemented Colour names of mineral concentrations nodules or mottles with a WH White stronger chroma or redder hue RE Red RS Reddish than the surrounding material YR Yellowish red A plinthic horizon. BR Brown 9Strongly cemented or indurated BS Brownish RB Reddish brown reddish to blackish nodules A YB Yellowish brown pisoplinthic horizon. YE Yellow RY Reddish yellow BIOLOGICAL ACTIVITY GE Greenish GR Grey In this section, evidence of past or GS Greyish present biological activity, including BU Blue human activity, is recorded. BB Bluish-black BL Black MC Multicoloured Roots The recording of both the size and the abundance of the roots is in general sufficient to characterize the distribution of roots in the profile. In specific cases, additional information can be noted, such as a sudden change in root orientation. The abundance of roots can only be compared within the same size class. The abundance of fine and very fine roots may be recorded similarly as for voids (Figure 8), expressed in the number of roots per decimetre square.
Size (diameter) Table 79 indicates the classification of the size of roots.
Abundance Table 80 indicates the classification of the abundance of roots.
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TABLE 79 Other biological features Classification of the diameter of roots Biological features, such as mm krotovinas, termite burrows, insect VF Very fine < 0.5 nests, worm casts and burrows of F Fine 0.5–2 M Medium 2–5 larger animals, are described in C Coarse > 5 terms of abundance and kind. Note: Additional codes are: FF, very fine and fine; FM, fine and In addition, specific locations, medium; and MC, medium and coarse. patterns, size, composition or any other characteristic may be TABLE 80 recorded. Classification of the abundance of roots < 2 mm > 2 mm N None 0 0 Abundance V Very few 1–20 1–2 Abundance of biological activity is F Few 20–50 2–5 recorded in the general descriptive C Common 50–200 5–20 terms indicated in Table 81. M Many > 200 > 20 Kind
TABLE 81 Examples of biological features are Classification of the abundance of biological activity given in Table 82. N None F Few Note for classification purposes C Common 9≥ 50 percent (by volume) of M Many wormholes, casts or filled animal burrows A voronic horizon and Vermic qualifier. TABLE 82 Examples of biological features 9≥ 25 percent (by volume) of A Artefacts animal pores, coprolites or B Burrows (unspecified) other traces of animal activity BO Open large burrows A hortic and irragric horizons. BI Infilled large burrows C Charcoal E Earthworm channels HUMAN-MADE MATERIALS P Pedotubules With the growing human influence T Termite or ant channels and nests in the world, especially in urban I Other insect activity and mining areas, it becomes increasingly important to document the type and degree of influence. Of particular importance are the human-made materials found in soils. Their age, amount, state and composition determine to a large extent the duration of human influence and the environmental impact.
Artefacts Artefacts (IUSS Working Group WRB, 2006) are solid or liquid substances that are: (i) created or modified substantially by humans as part of an industrial or artisanal manufacturing process; or (ii) brought to the surface by human activity
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from a depth where they were not influenced by surface processes. They have properties substantially different from the environment where they are placed, and they have substantially the same properties as when first manufactured, modified or excavated. This definition has several implications: ¾ “Liquid” includes chemicals of industrial origin. ¾ It does not include mining overburden that has been influenced by surface processes or transported soil. ¾ It includes excavated natural solids and liquids, such as coal, spilled crude oil and bitumen. ¾ The human origin must be evident in the material itself, not from written records or inference. ¾ If it has been transformed so that its origin is no longer identifiable, it is no longer an artefact. Some examples of artefacts are: ¾ synthetic solids (compounds not found in nature): slag and plastic; ¾ synthetic liquids: creosote and refined hydrocarbons; ¾ waste liquids: sludges (e.g. brewery and municipal); ¾ natural materials recognizably reworked by humans: flint knives and arrowheads; ¾ natural materials processed by humans into a form or composition not found in nature: pottery, bricks, concrete, asphalt and lead shot; ¾ mixed materials: building rubble; ¾ industrial dusts (both natural and synthetic); ¾ pavements and paving stones; ¾ natural materials minimally processed but mixed in a way not found in nature: organic garbage. ¾ mine spoil or crude oil
Note for classification purposes 9≥ 20 percent (by volume, by weighted average) artefacts A Technosols.
Human-transported material (HTM) Human-transported material (HTM) is any material in the soil to be classified brought from “outside”, often by machinery. This can be for agricultural purposes (e.g. large-scale terracing, mine spoil re-vegetation), for human settlement, or simply to dispose of material that is unwanted in its original location (e.g. dredgings). It is a parent material for pedogenesis, by analogy to fluvial sediments and colluvium. It has been defined as: “Human-transported material (abbreviation ‘HTM’): Any solid or liquid material moved into the soil from a source area outside of its immediate vicinity by intentional human activity, usually with the aid of machinery, without substantial reworking or displacement by natural forces” (Rossiter, 2004).
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The definition has several implications: ¾ The restriction to “intentional” excludes dusts from wind erosion or mass movement (e.g. slumps) caused by human activity. The intention must be inferred from the type of material and manner of deposition, not from historical records. ¾ “Liquids” can be of any viscosity and include slurries, liquid manures, hydrocarbons and other industrial chemicals transported by humans. ¾ If material originally transported by humans has been further moved by natural forces, such as erosion (water or wind) or flooding, the human influence is reduced, and it is no longer HTM. It is a different substrate and could be referred to as e.g. “colluvium from HTM”. ¾ Similarly, if the material is substantially reworked in situ (e.g. by frost), the human influence is reduced, and so it is no longer HTM. It could be referred to as “cyroturbated soil material originally human-transported”. ¾ The requirement that materials be moved farther than from the “immediate vicinity” excludes materials from ditching, terracing, etc. where the transported material is placed as close as possible to the source; the “transportation” is too local. HTM may be mixed with non-transported material, e.g. spoil that is partially ploughed into underlying natural soil. Thus, a soil layer may consist of part HTM and part non-transported (but reworked in situ) material. HTM may have substantial pedogenesis and still be identified as such. HTMs may be identified in several ways: ¾ by evidence of deposition processes after transportation (e.g. voids, compaction, and disorganized fragments of diagnostic horizons); ¾ by artefacts (not always present), although isolated artefacts may be mixed into non-transported soil by ploughing or bioturbation; ¾ by absence of evidence of transportation by natural forces (e.g. layering from flooding) or reworking in situ (e.g. cryoturbation); ¾ by absence of pedogenesis that masks evidence of deposition. In each case, the classifier must state the specific evidence for HTM. Historical evidence, e.g. site plans, may be used as an indication of where to find HTM but it is not diagnostic; this is the same as for fluvic sediments, which must be identified only from morphology, not from records of flooding.
Note for classification purposes 9HTM A Transportic qualifier.
Geomembranes and technic hard rock A geomembrane (IUSS Working Group WRB, 2006) is a synthetic membrane laid on the surface or into the soil or any other substrate. Many geomembranes are made of polyvinyl chloride (PVC) or high-density polyethylene (HDPE). Technic hard rock (IUSS Working Group WRB, 2006) is consolidated material resulting
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from an industrial process, with properties substantially different from those of natural materials.
Note for classification purposes 9A continuous, very slowly permeable to impermeable, constructed geomembrane starting within 100 cm of the soil surface A Technosols with the Linic qualifier. 9Technic hard rock starting within 5 cm of the soil surface and covering ≥ 95 percent of the horizontal extent of the soil A Technosols with the Ekranic qualifier.
Description of artefacts Artefacts are described according to their abundance, kind, size, hardness, weathering stage, and colour, if applicable.
Abundance Abundance is described with the same rules as for rock fragments (above).
Kind Table 83 lists the kinds of artefacts classified.
Size Size is described with the same rules as for rock fragments (above) or mineral nodules (above).
Hardness Hardness is described with the same rules as for mineral nodules (above).
Weathering State of weathering of the material is described with the same rules as for rock fragments (above).
Colour Colour is described with the same rules as for mineral nodules (above).
Note for classification purposes TABLE 83 9≥ 35 percent of the artefacts Classification of kinds of artefacts consisting of organic waste AN Artesanal natural material ID Industrial dust materials A Garbic qualifier. MM Mixed material 9≥ 35 percent of the artefacts OG Organic garbage consisting of industrial PS Pavements and paving stones waste materials (mine spoil, SL Synthetic liquid dredgings, rubble, etc.) A SS Synthetic solid WL Waste liquid Spolic qualifier.
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TABLE 84 Determination table and codes for human-made deposits 1 Observation at the profile a) stratified (spoiled materials) go to step 2 s... b) not stratified but clods of different colour, texture and/or artefacts go to step 3 d... (dumped substrate) 2 Test for colour and texture a) light to dark grey, fine sand to silt, coarser grains have vesicular pores fly and bottom ash ...UA2 b) dark grey to black, visible particles of coal coke mud ...UA2 c) light to dark brown, fine sand to silt, small Fe/Mn concretions dredge mud of rivers ...UA1
d) dark grey to black, H2S smell dredge mud of lakes ...UA1
e) dark grey to black, NH3 smell, artefacts sewage sludge ...UA2 f) dark grey to black, faecal smell, artefacts faecal sludge ...UA2 3 Test for texture, consistence and colour a) earthy, humic (grey to blackish grey) topsoil material ...UA1 b) loamy, with carbonates calcareous loam ...UU3 c) mainly sandy sand ...UU3 d) clayey clay ...UU1 e) mixture of sand, silt and clay loam ...UU2 f) mainly gravel gravel ...UU5 g) mainly broken rock broken rock ...UU5 h) > 30 percent pieces of grey to reddish-brown slag slag ...UA2 i) > 30 percent pieces of bricks and mortar and concrete construction rubble ...UA2
j) grey to black, H2S smell, > 30 percent artefacts (glass, ceramic, leather, waste ...UA2 wood, plastic, metals) Source: According to Meuser (1996), shortened.
9≥ 35 percent of the artefacts consisting of rubble and garbage of human settlements A Urbic qualifier.
Description and determination of human-transported material Where HTM is dominant, i.e. it occupies more than 50 percent (by volume) of the soil, it is sufficient to identify the type of HTM. Use the determination table (Table 84) and record the code.
SAMPLING The sample code and sampling depth are given. It is recommended that the number given to the sample be the profile number followed by an additional capital letter (A, B, C, D, etc.) and depth range at which each sample has been collected from top to bottom, regardless of the horizon they are taken from (some may not be sampled while others may be sampled twice). Samples are never taken across horizon boundaries. The weight of material taken for each sample is usually 1 kg. Horizon symbols should not be used as sample codes because the horizon classifications may be changed later.
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There are basically two methods of collecting samples: ¾ To collect the sample in equal proportions over the whole horizon. This is the recommended method and should be used for reference (Status 1) descriptions where a dense sampling is required. ¾ To take the sample in equal proportions within a depth of 20 cm, either from the centre (area of maximum expression) of the horizon, or, if more than one sample is to be taken from the same horizon, at balanced intervals. In both methods, the boundary area itself should not be sampled. In detailed descriptions of soils with horizons no more than 30–40 cm thick, there will be little difference between the two methods in practice. It is recommended that the topsoil be sampled within the first 20 cm of the surface, or shallower where the horizon depth is less. This will facilitate comparison of topsoil characteristics in soil inventories and land evaluation. If the presence of a mollic horizon is assumed, the sampling depth for a soil with a solum more than 60 cm thick may be more than 20 cm but not exceeding 30 cm. Depth criteria of diagnostic horizons and properties should be taken into account in determining the depth of sampling. To indicate the occurrence of an argic horizon that is defined as having a specified clay increase over a vertical distance of 15 or 30 cm, the samples are preferably taken at that depth interval (e.g. A 0–20 cm, B 20–30 cm or 30–50 cm). Another example is for the classification of Nitisols: a sample should be taken at a depth of 140–160 cm, in addition to the one taken from that part of the B horizon where the clay content is assumed to be highest.
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Chapter 5 Genetic and systematic interpretation – soil classification
SOIL HORIZON DESIGNATION The soil horizon designation summarizes many observations of the soil description and gives an impression about the genetic processes that have formed the soil under observation. In this chapter, the soil morphological and other characteristics are presented as they are described by horizon. Horizon symbols consist of one or two capital letters for the master horizon and lower case letter suffixes for subordinate distinctions, with or without a figure suffix. For the presentation and understanding of the soil profile description, it is essential that correct horizon symbols be given.
Master horizons and layers The capital letters H, O, A, E, B, C, R, I, L and W represent the master horizons or layers in soils or associated with soils. The capital letters are the base symbols to which other characters are added in order to complete the designation. Most horizons and layers are given a single capital letter symbol, but some require two. Currently, ten master horizons and layers and seven transitional horizons are recognized. The master horizons and their subdivisions represent layers that show evidence of change and some layers that have not been changed. Most are genetic soil horizons, reflecting a qualitative judgement about the kind of changes that have taken place. Genetic horizons are not equivalent to diagnostic horizons, although they may be identical in soil profiles. Diagnostic horizons are quantitatively defined features used in classification. Three additional layers associated with some soils are identified, viz. I for ice, L for limnic materials, and W for water layers.
H horizons or layers These are layers dominated by organic material formed from accumulations of undecomposed or partially decomposed organic material at the soil surface, which may be underwater. All H horizons are saturated with water for prolonged periods, or were once saturated but are now drained artificially. An H horizon may be on top of mineral soils or at any depth beneath the surface if it is buried.
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O horizons or layers These are layers dominated by organic material consisting of undecomposed or partially decomposed litter, such as leaves, needles, twigs, moss and lichens, that has accumulated on the surface; they may be on top of either mineral or organic soils. O horizons are not saturated with water for prolonged periods. The mineral fraction of such material is only a small percentage of the volume of the material and is generally much less than half of the weight. An O layer may be at the surface of a mineral soil or at any depth beneath the surface where it is buried. A horizon formed by illuviation of organic material into mineral subsoil is not an O horizon, although some horizons formed in this manner contain much organic matter.
A horizons These are mineral horizons that formed at the surface or below an O horizon, in which all or much of the original rock structure has been obliterated and which are characterized by one or more of the following: ¾ an accumulation of humified organic matter intimately mixed with the mineral fraction and not displaying properties characteristic of E or B horizons (see below); ¾ properties resulting from cultivation, pasturing, or similar kinds of disturbance; ¾ a morphology that is different from the underlying B or C horizon, resulting from processes related to the surface. If a surface horizon (or epipedon) has properties of both A and E horizons but the dominant feature is an accumulation of humified organic matter, it is designated an A horizon. In some places, where warm and arid climates prevail, the undisturbed surface horizon is less dark than the underlying horizon and contains only small amounts of organic matter. It has a morphology distinct from the C layer, although the mineral fraction may be unaltered or only slightly altered by weathering. Such a horizon is designated A because it is at the surface. Examples of epipedons that may have a different structure or morphology owing to surface processes are Vertisols, soils in pans or playas with little vegetation, and soils in deserts. However, recent alluvial or aeolian deposits that retain fine stratification are not considered to be an A horizon unless cultivated.
E horizons These are mineral horizons in which the main feature is loss of silicate clay, iron, aluminium, or some combination of these, leaving a concentration of sand and silt particles, and in which all or much of the original rock structure has been obliterated. An E horizon is usually, but not necessarily, lighter in colour than an underlying B horizon. In some soils, the colour is that of the sand and silt particles, but in many soils coatings of iron oxides or other compounds mask the colour of
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the primary particles. An E horizon is most commonly differentiated from an underlying B horizon in the same soil profile: by colour of higher value or lower chroma, or both; by coarser texture; or by a combination of these properties. An E horizon is commonly near the surface, below an O or A horizon and above a B horizon. However, the symbol E may be used without regard to position in the profile for any horizon that meets the requirements and that has resulted from soil genesis.
B horizons These are horizons that formed below an A, E, H or O horizon, and in which the dominant features are the obliteration of all or much of the original rock structure, together with one or a combination of the following: ¾ illuvial concentration, alone or in combination, of silicate clay, iron, aluminium, humus, carbonates, gypsum or silica; ¾ evidence of removal of carbonates; ¾ residual concentration of sesquioxides; ¾ coatings of sesquioxides that make the horizon conspicuously lower in value, higher in chroma, or redder in hue than overlying and underlying horizons without apparent illuviation of iron; ¾ alteration that forms silicate clay or liberates oxides or both and that forms a granular, blocky or prismatic structure if volume changes accompany changes in moisture content; ¾ brittleness. All kinds of B horizons are, or were originally, subsurface horizons. Included as B horizons are layers of illuvial concentration of carbonates, gypsum or silica that are the result of pedogenetic processes (these layers may or may not be cemented) and brittle layers that have other evidence of alteration, such as prismatic structure or illuvial accumulation of clay. Examples of layers that are not B horizons are: layers in which clay films either coat rock fragments or are on finely stratified unconsolidated sediments, whether the films were formed in place or by illuviation; layers into which carbonates have been illuviated but that are not contiguous to an overlying genetic horizon; and layers with gleying but no other pedogenetic changes.
C horizons or layers These are horizons or layers, excluding hard bedrock, that are little affected by pedogenetic processes and lack properties of H, O, A, E or B horizons. Most are mineral layers, but some siliceous and calcareous layers, such as shells, coral and diatomaceous earth, are included. The material of C layers may be either like or unlike that from which the solum presumably formed. A C horizon may have been modified even where there is no evidence of pedogenesis. Plant roots can penetrate C horizons, which provide an important growing medium. Included as C layers are sediments, saprolite, and unconsolidated bedrock and other geological materials that commonly slake within 24 hours when air dry or
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drier chunks are placed in water and when moist can be dug with a spade. Some soils form in material that is already highly weathered, and such material that does not meet the requirements of A, E or B horizons is designated C. Changes not considered pedogenetic are those not related to overlying horizons. Layers having accumulations of silica, carbonates or gypsum, even if indurated, may be included in C horizons unless the layer is obviously affected by pedogenetic processes; then it is a B horizon.
R layers These consist of hard bedrock underlying the soil. Granite, basalt, quartzite and indurated limestone or sandstone are examples of bedrock that are designated R. Air-dry or drier chunks of an R layer when placed in water will not slake within 24 hours. The R layer is sufficiently coherent when moist to make hand digging with a spade impractical, although it may be chipped or scraped. Some R layers can be ripped with heavy power equipment. The bedrock may contain cracks, but these are so few and so small that few roots can penetrate. The cracks may be coated or filled with clay or other material.
I layers These are ice lenses and wedges that contain at least 75 percent ice (by volume) and that distinctly separate organic or mineral layers in the soil. Ice comes and goes in soils in areas affected by permafrost. Ice bodies in soils can grow to such an extent that they form lenses of wedges that separate entire soil layers. In case such, where ice concentrations occur within the depth of soil description, they can be designated as an I layer. The I symbol is not used in transitional horizon designations.
L layers These are sediments deposited in a body of water (subaqueous) composed of both organic and inorganic materials, also known as limnic material. Limnic material is either: (i) deposited by precipitation or through action of aquatic organisms, such as algae or diatoms; or (ii) derived from underwater and floating aquatic plants and subsequently modified by aquatic animals (USDA Soil Survey Staff, 2003). L layers include coprogenous earth or sedimentary peat (mostly organic), diatomaceous earth (mostly siliceous), and marl (mostly calcareous). The L symbol is not used in transitional horizon designations.
W layers These are water layers in soils or water submerging soils, either permanently or cyclic within the time frame of 24 hours. Some organic soils float on water. In such cases, the W symbol may be used at the end of the soil description to indicate the floating character. In other cases, shallow water (i.e. water not deeper than 1 m) may cover the soil permanently, as in the case of shallow lakes, or cyclic, as in tidal flats. The symbol W is then used
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to indicate the depth of submergence at the start of the horizon or layer sequence. The occurrence of tidal water can be indicated by (W).
Transitional horizons There are two kinds of transitional horizons: those with properties of two horizons superimposed; and those with the two properties separate. For horizons dominated by properties of one master horizon but having subordinate properties of another, two capital letter symbols are used, such as AB, EB, BE and BC. The master horizon symbol that is given first designates the kind of horizon whose properties dominate the transitional horizon. For example, an AB horizon has characteristics of both an overlying A horizon and an underlying B horizon, but it is more like the A than like the B. In some cases, a horizon can be designated as transitional even if one of the master horizons to which it is apparently transitional is not present. A BE horizon may be recognized in a truncated soil if its properties are similar to those of a BE horizon in a soil in which the overlying E horizon has not been removed by erosion. An AB or a BA horizon may be recognized where bedrock underlies the transitional horizon. A BC horizon may be recognized even if no underlying C horizon is present; it is transitional to assumed parent material. A CR horizon can be used for weathered bedrock that can be dug with a spade although roots cannot penetrate except along fracture planes. Horizons in which distinct parts have recognizable properties of two kinds of master horizons are indicated as above, but the two capital letters are separated by a virgule (/), such as E/B, B/E, B/C and C/R. Commonly, most of the individual parts of one of the components are surrounded by the other. The I, L and W symbols are not used in transitional horizon designations.
Subordinate characteristics within master horizons and layers Designations of subordinate distinctions and features within the master horizons and layers are based on profile characteristics observable in the field and are applied during the description of the soil at the site. Lower case letters are used as suffixes to designate specific kinds of master horizons and layers, and other features. The list of symbols and terms is shown in Table 85 and explanations of them are given below: a. Highly decomposed organic material: Used with H and O horizons only, to indicate the state of decomposition of the organic material. Highly decomposed organic material has less than one-sixth (by volume) visible plant remains. b. Buried genetic horizon: Used in mineral soils to indicate identifiable buried horizons with major genetic features that were formed before burial. Genetic horizons may or may not have formed in the overlying materials, which may be either like or unlike the assumed parent materials of the buried soil. The symbol is not used in organic soils or to separate an organic layer from a mineral layer, in cryoturbated soils, or with C horizons.
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TABLE 85 Subordinate characteristics within master horizons Suffix Short description Used for a Highly decomposed organic material H and O horizons b Buried genetic horizon mineral horizons, not cryoturbated c Concretions or nodules mineral horizons c Coprogenous earth L horizon d Dense layer (physically root restrictive) mineral horizons, not with m d Diatomaceous earth L horizon e Moderately decomposed organic material H and O horizons f Frozen soil not in I and R horizons g Stagnic conditions no restriction h Accumulation of organic matter mineral horizons i Slickensides mineral horizons i Slightly decomposed organic material H and O horizons j Jarosite accumulation no restriction k Accumulation of pedogenetic carbonates no restriction l Capillary fringe mottling (gleying) no restriction m Strong cementation or induration (pedogenetic, massive) mineral horizons m Marl L horizon n Pedogenetic accumulation of exchangeable sodium no restriction o Residual accumulation of sesquioxides (pedogenetic) no restriction p Ploughing or other human disturbance no restriction, E, B or C as Ap q Accumulation of pedogenetic silica no restriction r Strong reduction no restriction s Illuvial accumulation of sesquioxides B horizons t Illuvial accumulation of silicate clay B and C horizons u Urban and other human-made materials H, O, A, E, B and C horizons v Occurrence of plinthite no restriction w Development of colour or structure B horizons x Fragipan characteristics no restriction y Pedogenetic accumulation of gypsum no restriction z Pedogenetic accumulation of salts more soluble than gypsum no restriction @ Evidence of cryoturbation no restriction
c. Concretions or nodules: In mineral soil, it indicates a significant accumulation of concretions or nodules. The nature and consistence of the nodules is specified by other suffixes and in the horizon description. Coprogenous earth: With limnic material L it denotes coprogenous earth, i.e. organic materials deposited under water and dominated by faecal material from aquatic animals. d. Dense layer: Used in mineral soils to indicate a layer of relatively unaltered, mostly earthy material that is non-cemented, but that has such bulk density or internal organization that roots cannot enter except in cracks; the symbol is not used in combination with the symbols m (cementation) and x (fragipan). Diatomaceous earth: In combination with limnic material L, it is used
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to indicate diatomaceous earth, i.e. materials deposited under water and dominated by the siliceous remains of diatoms. e. Moderately decomposed organic materials: Used with H and O horizons only, to indicate the state of decomposition of the organic material. Moderately decomposed organic material has between one-sixth and two- thirds (by volume) visible plant remains. f. Frozen soil: Designates horizons or layers that contain permanent ice or are perennially colder than 0 °C. It is not used for seasonally frozen layers or for bedrock layers (R). If needed, “dry frozen soil” layers may be labelled (f). g. Stagnic conditions: Designates horizons in which a distinct pattern of mottling occurs that reflects alternating conditions of oxidation and reduction of sesquioxides, caused by seasonal surface waterlogging. If aggregates are present, the interiors of the aggregates show oxidizing colours and the surface parts reducing colours. h. Accumulation of organic matter: Designates the accumulation of organic matter in mineral horizons. The accumulation may occur in surface horizons, or in subsurface horizons through illuviation. i. Slickensides: Denotes in mineral soils the occurrence of slickensides, i.e. oblique shear faces 20–60 º of horizontal owing to the shrink–swell action of clay; wedge-shaped peds and seasonal surface cracks are commonly present. Slightly decomposed organic material: In organic soils and used in combination with H or O horizons, it indicates the state of decomposition of the organic material; slightly decomposed organic material has in more than two-thirds (by volume) visible plant remains. j. Jarosite: Indicates the presence of jarosite mottles, coatings or hypodermic coatings. k. Accumulation of pedogenetic carbonates: Indicates an accumulation of alkaline earth carbonates, commonly calcium carbonate. l. Capillary fringe mottling: Indicates mottling caused by ascending groundwater. If aggregates are present, the interiors of the aggregates show reducing colours and the surface parts oxidizing colours. Strong cementation or induration: Indicates in mineral soils continuous or nearly continuous cementation, and is used only for horizons that are more than 90 percent cemented, although they may be fractured. The layer is root restrictive and roots do not enter except along fracture planes. The single predominant or codominant cementing agent may be indicated using defined letter suffices single or in pairs. If the horizon is cemented by carbonates km is used; by silica, qm; by iron, sm; by gypsum, ym; by both lime and silica, kqm; and by salts more soluble than gypsum, zm. Marl: In combination with limnic material it is used to indicate marl, i.e. materials deposited under water and dominated by a mixture of clay and calcium carbonate; typically grey in colour. n. Pedogenetic accumulation of exchangeable sodium: Indicates an accumulation of exchangeable sodium.
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o. Residual accumulation of sesquioxides: Indicates residual accumulation of sesquioxides. It differs from the use of symbol s, which indicates illuvial accumulation of organic matter and sesquioxide complexes. p. Ploughing or other human disturbance: Indicates disturbance of the surface layer by ploughing or other tillage practices. A disturbed organic horizon is designated Op or Hp. A disturbed mineral horizon, even though clearly once an E, B or C, is designated Ap. q. Accumulation of pedogenetic silica: Indicates an accumulation of secondary silica. If silica cements the layer and cementation is continuous or nearly continuous, qm is used. r. Strong reduction: Indicates presence of iron in reduced state. If r is used with B, pedogenetic change in addition to reduction is implied; if no other change has taken place, the horizon is designated Cr. s. Illuvial accumulation of sesquioxides: Used with B to indicate the accumulation of illuvial, amorphous, dispersible organic matter–sesquioxide complexes if the value and chroma of the horizon are more than 3. The symbol is also used in combination with h as Bhs if both the organic matter and sesquioxides components are significant and both value and chroma are about 3 or less. t. Accumulation of silicate clay: Used with B or C to indicate an accumulation of silicate clay that either has formed in the horizon or has been moved into it by illuviation, or both. At least some part should show evidence of clay accumulation in the form of coatings on ped surfaces or in pores, as lamellae, or as bridges between mineral grains. u. Urban and other human-made materials: Used to indicate the dominant presence of human-made materials, including technogenic ones. The symbol can be used in combination with H, O, A, E, B and C. v. Occurrence of plinthite: Indicates the presence of iron-rich, humus-poor material that is firm or very firm when moist and that hardens irreversibly when exposed to the atmosphere. When hardened, it is no longer called plinthite but a hardpan, ironstone, a petroferric or a skeletic phase. In that case, v is used in combination with m. w.Development of colour or structure in B: Used with B only to indicate development of colour or structure, or both. It is not used to indicate a transitional horizon. x. Fragipan characteristics: Used to indicate genetically developed firmness, brittleness or high bulk density. These features are characteristic of fragipans, but some horizons designated x do not have all the properties of a fragipan. y. Pedogenetic accumulation of gypsum: Indicates an accumulation of gypsum. z. Pedogenetic accumulation of salts more soluble than gypsum: Indicates an accumulation of salts more soluble than gypsum. @ Evidence of cryoturbation: irregular or broken boundaries, sorted rock fragments (patterned ground), or organic matter in the lower boundary
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between the active layer and permafrost layer. The suffix is always used last, e.g. Hi@.
Conventions for using letter suffixes Many master horizons and layers that are symbolized by a single capital letter will have one or more lowercase letter suffixes. More than three suffixes are rarely used. The following rules apply: ¾ Letter suffixes should follow the capital letter immediately. ¾ When more than one suffix is needed, the following letters, if used, are written first: r, s, t, u and w. The symbol t has precedence over all other symbols, e.g. Btr, Btu. In all other combinations, the symbols are listed alphabetically, e.g. Cru. ¾ If more than one suffix is needed and the horizon is not buried, these symbols, if used, are written last: c, f, g, m, v and x. Some examples: Btc, Bkm, and Bsv. ¾ If a horizon is buried, the suffix b is written last. ¾ A B horizon that has significant accumulation of clay and also shows evidence of development of colour or structure, or both, is designated Bt (t has precedence over w, s and h). A B horizon that is gleyed or that has accumulations of carbonates, sodium, silica, gypsum, salts more soluble than gypsum, or residual accumulation or sesquioxides carries the appropriate symbol g, k, n, q, y, z or o. If illuvial clay is also present, t precedes the other symbols, e.g. Bto. ¾ Suffixes h, s and w are normally not used with g, k, n, q, y, z or o unless needed for explanatory purposes. ¾ Suffixes a and e are used only in combination with H or O. ¾ Suffixes c, d, i and m have two different meanings, depending on the master horizon designation they are coupled to. The different combinations are mutually exclusive, e.g. Bi indicates presence of slickensides in the B horizon, whereas Hi indicates a slightly decomposed H horizon. Similarly, Bd indicates a dense B horizon, and Ld diatomaceous earth in a limnic layer. ¾ Suffix @ is always used last, and cannot be combined with b. ¾ Unless otherwise indicated, suffixes are listed alphabetically.
Vertical subdivisions Horizons or layer designated by a single combination of letter symbols can be subdivided using Arabic numerals, which follow all the letters. For example, within a C, successive layers could be C1, C2, C3, etc.; or if the lower part is gleyed and the upper part is not, the designations could be C1-C2-Cg1-Cg2 or C-Cg1-Cg2-R. These conventions apply whatever the purpose of subdivision. A horizon identified by a single set of letter symbol may be subdivided on the basis of evident morphological features, such as structure, colour or texture. These subdivisions are numbered consecutively. The numbering starts with 1 at whatever level in the
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profile. Thus, Bt1-Bt2-Btk1-Btk2 is used, not Bt1-Bt2-Btk3-Btk4. The numbering of vertical subdivisions within a horizon is not interrupted at a discontinuity (indicated by a numerical prefix) if the same letter combination is used in both materials: Bs1-Bs2-2Bs3-2Bs4 is used, not Bs1-Bs2-2Bs1-2Bs2. A and E horizons can be subdivided similarly, e.g. Ap, A1, A2; Ap1, Ap2; A1, A2, A3; and E1, E2, Eg1, Eg2.
Discontinuities In mineral soils, Arabic numerals are used as prefixes to indicate discontinuities. Wherever needed, they are used preceding A, E, B, C and R. They are not used with I and W, although these symbols clearly indicate a discontinuity. These prefixes are distinct from Arabic numerals used as suffixes to denote vertical subdivisions. A discontinuity is a significant change in particle-size distribution or mineralogy that indicates a difference in the material from which the horizons formed or a significant difference in age or both, unless that difference in age is indicated by the suffix b. Symbols to identify discontinuities are used only when they will contribute substantially to the reader’s understanding of relationships among horizons. The stratification common in soils formed in alluvium is not designated as discontinuities unless particle-size distribution differs markedly from layer to layer even though genetic horizons have formed in the contrasting layers. Where a soil has formed entirely in one kind of material, a prefix is omitted from the symbol; the whole profile is material 1. Similarly, the uppermost material in a profile having two or more contrasting materials is understood to be material 1, but the number is omitted. Numbering starts with the second layer of contrasting material, which is designated 2. Underlying contrasting layers are numbered consecutively. Even where a layer below material 2 is similar to material 1, it is designated 3 in the sequence. The numbers indicate a change in the material, not the type of material. Where two or more consecutive horizons formed in one kind of material, the same prefix number applies to all of the horizon designations in that material: Ap-E-Bt1-2Bt2-2Bt3-2BC. The number suffixes designating subdivisions of the Bt horizon continue in consecutive order across the discontinuity. If an R layer is below a soil that formed in residuum and the material of the R layer is judged to be like that from which the material of the soil weathered, the Arabic number prefix is not used. If the R layer would not produce material like that in the solum, the number prefix is used, as in A-Bt-C-2R or A-Bt-2R. If part of the solum formed in residuum, R is given the appropriate prefix: Ap-Bt1-2Bt2- 2Bt3-2C1-2C2-2R. Buried horizons (designated b) are special problems. A buried horizon is not the same deposit as horizons in the overlying deposit. However, some buried horizons formed in material lithological like that of the overlying deposit. A prefix is not used to distinguish material of such buried horizons. If the material in which a horizon of a buried soil formed is lithological unlike that of the
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overlying material, the discontinuity is designated by number prefixes and the symbol for a buried horizon is used as well: Ap-Bt1-Bt2-BC-C-2ABb-2Btb1- 2Btb2-2C. In organic soils, discontinuities between different kinds of layers are not identified. In most cases, the differences are shown by the letter suffix designations, if the different layers are organic, or by the master symbol if the different layers are mineral.
Use of the prime Identical designations may be appropriate for two or more horizons or layers separated by at least one horizon or layer of a more different kind in the same pedon. The sequence A-E-Bt-E-Btx-C is an example – the soil has two E horizons. To make communication easier, a prime is used with the master horizon symbol of the lower of two horizons having identical letter designations: A-E-Bt-E’-Btx-C. The prime is applied to the capital letter designation, and any lower case symbol follows it: B’t. The prime is not used unless all letters of the designations of two different layers are identical. Rarely, three layers have identical letter symbols; a double prime can be used: E’’. The same principle applies in designating layers of organic soils. The prime is used only to distinguish two or more horizons that have identical symbols: O-C-C’-C’’. The prime is added to the lower C layer to differentiate it from the upper.
PRINCIPLES OF CLASSIFICATION ACCORDING TO THE WRB The surveyor should attempt to classify the soil in the field as precisely as possible on the basis of the soil morphological features that have been observed and described. The final classification is made after the analytical data have become available. It is recommended that the occurrence and depth of diagnostic horizons, properties and materials identified be listed (below). The general principles on which the classification according to the WRB is based (IUSS Working Group WRB 2006)can be summarized as follows: ¾ The classification of soils is based on soil properties defined in terms of diagnostic horizons, properties and materials, which to the greatest extent possible should be measurable and observable in the field. ¾ The selection of diagnostic characteristics takes into account their relationship with soil forming processes. It is recognized that an understanding of soil- forming processes contributes to a better characterization of soils but that they should not, as such, be used as differentiating criteria. ¾ To the extent possible at a high level of generalization, diagnostic features are selected that are of significance for soil management. ¾ Climate parameters are not applied in the classification of soils. It is fully realized that they should be used for interpretation purposes, in dynamic combination with soil properties, but they should not form part of soil definitions.
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¾ The WRB is a comprehensive classification system that enables people to accommodate their national classification system. It comprises two tiers of categorical detail: • the Reference Base, limited to the first level only and having 32 RSGs; • the WRB Classification System, consisting of combinations of a set of prefix and suffix qualifiers that are uniquely defined and added to the name of the RSG, allowing very precise characterization and classification of individual soil profiles. ¾ Many RSGs in the WRB are representative of major soil regions so as to provide a comprehensive overview of the world’s soil cover. ¾ The Reference Base is not meant to substitute for national soil classification systems but rather to serve as a common denominator for communication at an international level. This implies that lower-level categories, possibly a third category of the WRB, could accommodate local diversity at country level. Concurrently, the lower levels emphasize soil features that are important for land use and management. ¾ The Revised Legend of the FAO/UNESCO Soil Map of the World (FAO, 1988) has been used as a basis for the development of the WRB in order to take advantage of international soil correlation that has already been conducted through this project and elsewhere. ¾ The first edition of the WRB, published in 1998, comprised 30 RSGs; the second edition, published in 2006, has 32 RSGs. ¾ Definitions and descriptions of soil units reflect variations in soil characteristics both vertically and laterally in order to account for spatial linkages within the landscape. ¾ The term Reference Base is connotative of the common denominator function that the WRB assumes. Its units have sufficient width to stimulate harmonization and correlation of existing national systems. ¾ In addition to serving as a link between existing classification systems, the WRB also serves as a consistent communication tool for compiling global soil databases and for the inventory and monitoring of the world’s soil resources. ¾ The nomenclature used to distinguish soil groups retains terms that have been used traditionally or that can be introduced easily in current language. They are defined precisely in order to avoid the confusion that occurs where names are used with different connotations. Although the basic framework of the FAO Legend (with its two categorical levels and guidelines for developing classes at a third level) was adopted, it has been decided to merge the lower levels. Each RSG of the WRB is provided with a listing of possible prefix and suffix qualifiers in a priority sequence, from which the user can construct the second-level units. The broad principles that govern the WRB class differentiation are: ¾ At the higher categorical level, classes are differentiated mainly according to the primary pedogenetic process that has produced the characteristic soil features, except where special soil parent materials are of overriding importance.
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¾ At the second level, soil units are differentiated according to any secondary soil-forming process that has affected the primary soil features significantly. In certain cases, soil characteristics that have a significant effect on use may be taken into account. It is recognized that a number of RSGs may occur under different climate conditions. However, it was decided not to introduce separations on account of climate characteristics so that the classification of soils is not subordinated to the availability of climate data. Including the soil description, classification is done in four steps.
Step 1 The profile description is checked to find references to soil-forming processes (qualitatively) and express them in the horizon designation. Examples may be: ¾ Darkening of topsoil in comparison to subsoil A enrichment with organic material A Ah-horizon. ¾ Browning and finer texture in the middle part of a soil profile in comparison to the parent material A enrichment of Fe-oxides and clay A weathering A Bw-horizon.
Step 2 The profile description and the horizon designation are to be checked whether the expression, thickness and depth of certain soil characteristics correspond with the requirements of WRB diagnostic horizons, properties and materials. These are defined in terms of morphological characteristics and/or analytical criteria (IUSS Working Group WRB, 2006). In line with the WRB objectives, attributes are described as much as possible to support field identification.
Step 3 The described combination of diagnostic horizons, properties and materials is compared with the WRB Key (IUSS Working Group WRB, 2006) in order to find the RSG, which is the first level of WRB classification. The user should go through the Key systematically, starting at the beginning and excluding one by one all RSGs for which the specified requirements are not met. The soil belongs to the first RSG for which it meets all specified requirements.
Step 4 For the second level of WRB classification, qualifiers are used. The qualifiers are listed in the Key with each RSG as prefix and suffix qualifiers. Prefix qualifiers comprise those that are typically associated to the RSG and the intergrades to other RSGs. All other qualifiers are listed as suffix qualifiers. For classification at the second level, all applying qualifiers have to be added to the name of the RSG. Redundant qualifiers (the characteristics of which are included in a previously set qualifier) are not added.
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Specifiers can be used to indicate the degree of expression of qualifiers. Buried layers can be indicated by the Thapto- specifier, which can be used with any qualifier, listed in IUSS Working Group WRB (2006). Where a soil is buried under new material, the following rules apply: 1. The overlying new material and the buried soil are classified as one soil if both together qualify as Histosol, Technosol, Cryosol, Leptosol, Vertisol, Fluvisol, Gleysol, Andosol, Planosol, Stagnosol or Arenosol. 2. Otherwise, the new material is classified at the first level if the new material is 50 cm or more thick or if the new material, if it stood alone, fits the requirements of a RSG other than a Regosol. 3. In all other cases, the buried soil is classified at the first level. 4. If the overlying soil is classified at the first level, the buried soil is recognized with the Thapto- specifier and -ic added to the RSG name of the buried soil. The whole is placed in brackets after the name of the overlying soil, e.g. Technic Umbrisol (Greyic) (Thapto-Podzolic). If the buried soil is classified at the first level, the overlying material is indicated with the Novic qualifier.
Principles and use of the qualifiers in the WRB A two-tier system is used for the qualifier level, comprising: ¾ Prefix qualifiers: typically associated qualifiers and intergrade qualifiers; the sequence of the intergrade qualifiers follows that of the RSGs in the WRB Key, with the exception of Arenosols; this intergrade is ranked with the textural suffix qualifiers (see below). Haplic closes the prefix qualifier list indicating that neither typically associated nor intergrade qualifiers apply. ¾ Suffix qualifiers: other qualifiers, sequenced as follows: (1) qualifiers related to diagnostic horizons, properties or materials; (2) qualifiers related to chemical characteristics; (3) qualifiers related to physical characteristics; (4) qualifiers related to mineralogical characteristics; (5) qualifiers related to surface characteristics; (6) qualifiers related to textural characteristics, including coarse fragments; (7) qualifiers related to colour; and (8) remaining qualifiers. Prefix qualifier names are always put before the RSG; suffix qualifier names are always placed between brackets following the RSG name. Combinations of qualifiers that indicate a similar status or duplicate each other are not permitted, such as combinations of Thionic and Dystric, Calcaric and Eutric, or Rhodic and Chromic. Specifiers such as Epi-, Endo-, Hyper-, Hypo-, Thapto-, Bathy-, Para-, Proto-, Cumuli- and Ortho- are used to indicate a certain expression of the qualifier. When classifying a soil profile, all applying qualifiers of the listing must be recorded. For mapping purposes, the scale will determine the number of qualifiers used. In that case, prefix qualifiers have priority over the suffix qualifiers. The qualifier listing for each RSG accommodates most cases. Where not listed qualifiers are needed, the cases should be documented and reported to the WRB Working Group.
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The field classification provides a preliminary assessment using all observable or easily measurable properties and features of the soil and associated terrain. The final classification is made when analytical data are available. It is recommended that Procedures for Soil Analysis (Van Reeuwijk, 2006) be followed in determining chemical and physical characteristics.
Example of WRB soil classification A soil has a ferralic horizon; texture in the upper part of the ferralic horizon changes from sandy loam to sandy clay within 15 cm. The pH is between 5.5 and 6, indicating moderate to high base saturation. The B horizon is dark red; below 50 cm, mottling occurs. The field classification of this soil is: Lixic Ferralsol (Ferric, Rhodic). If subsequent laboratory analysis reveals that the cation exchange -1 capacity of the ferralic horizon is less than 4 cmolc kg clay, the soil finally classifies as: Lixic Vetic Ferralsol (Ferric, Rhodic).
CHECKLIST OF WRB DIAGNOSTIC HORIZONS, PROPERTIES AND MATERIALS While still in the field, it is advisable to determine or estimate, for each horizon, the diagnostic characteristics that apply to the classification system used. Table 86 provides a checklist of diagnostic horizons, properties and materials in the order as they appear in the WRB (IUSS Working Group WRB, 2006).
TABLE 86 Checklist of WRB diagnostic horizons, properties and materials Diagnostic horizons Diagnostic properties Diagnostic materials Albic horizon Natric horizon Abrupt textural change Artefacts Anthraquic horizon Nitic horizon Albeluvic tonguing Calcaric material Anthric horizon Petrocalcic horizon Andic properties Colluvic material Argic horizon Petroduric horizon Aridic properties Fluvic material Calcic horizon Petrogypsic horizon Continuous rock Gypsiric material Cambic horizon Petroplinthic horizon Ferralic properties Limnic material Cryic horizon Pisoplinthic horizon Geric properties Mineral material Duric horizon Plaggic horizon Gleyic colour pattern Organic material Ferralic horizon Plinthic horizon Lithological discontinuity Ornithogenic material Ferric horizon Salic horizon. Reducing conditions Sulphidic material Folic horizon Sombric horizon Secondary carbonates Technic hard rock Fragic horizon Spodic horizon Stagnic colour pattern Tephric material Fulvic horizon Takyric horizon Vertic properties Gypsic horizon Terric horizon Vitric properties Histic horizon Thionic horizon Hortic horizon Umbric horizon Hydragric horizon Vertic horizon Irragric horizon Voronic horizon Melanic horizon Yermic horizon Mollic horizon
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APPENDING TEXTURE AND PARENT MATERIAL INFORMATION TO THE REFERENCE SOIL GROUP In its present state, the WRB (IUSS Working Group WRB, 2006) is, by history and practical purposes, mixing information about soil genesis (e.g. podzolization – Podzol, gleysation – Gleysol), texture (e.g. Arenosol, skeletic, arenic, siltic, and clayic subunits), parent materials (e.g. Anthrosols, Fluvisols, calcaric, and gypsiric subunits) and others. The system distinguishes second-level units only in a generalized manner by texture and only in the parent material of some RSGs. In order to overcome this problem and to provide users with more systematic and precise information about texture, parent material and layering, the following framework for a reference soil series is recommended (Jahn, 2004).
Example A Cambisol to which only the Dystric qualifier applies and which has variations in texture and in which the upper part has developed from loess with some fluvial gravelly sand and the lower part has developed from glacio-fluvial gravelly sand. The full description is: Haplic Cambisol (Dystric); silt loam from loess with glacio-fluvial gravelly sand over sandy skeleton from glacio-fluvial gravel It is coded: CMdy; SiL(UE2, UG2)/SSK(UG3) 1 2 3 4 5 1 = Coding of soil unit according to the WRB (IUSS Working Group WRB, 2006). 2 = Coding of texture class for the upper part of the soil body. The texture class for the fine earth is used according to Chapter 4 and combined with four classes of coarse fragments, e.g.: SiL = silt loam with coarse fragments < 10 percent (by volume); skSiL = skeletal silt loam with coarse fragments of from 10 to < 40 percent (by volume); silSK = silt loamy skeleton with coarse fragments of from 40 to <80 percent (by volume); SK = skeleton with coarse fragments of 80 percent or more (by volume). 3 = The parent material is given in descending order of importance from left to right within brackets. For coding, an extended hierarchical lithology list, based on updated SOTER (ISRIC, 2005) is used. 4 = A change of material with depth (either by texture or by parent material or by both is coded with: ...\... as “shallow … over …” where occurring at a depth of 0–3 dm; .../... as “… over …” where occurring at a depth of 3–7 dm; (the intermediate of 5 dm is corresponding with the WRB-epi and -endo); ...//... as “… over deep …” where occurring at a depth of 7–12 dm. 5 = The lower part of the soil body is described according to 2 and 3.
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Further rules in describing texture and parent material are: ¾ e.g.: skSiL(UE2, UG2/UG3) where no change in texture but in parent material; ¾ e.g.: SiL/skSiL(UE2, UG3) where no change in parent material but in texture; ¾ e.g.: .../R(and lithology) means: over massive rock; ¾ Horizons are combined to one complex and described with the average where not more than one of the three parameters: (1) texture (fine earth); (2) coarse fragments; and (3) lithology differs for one class. Thin (extension < 2 cm ) horizons are neglected.
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References
Ad-hoc-AG-Boden. 2005. Bodenkundliche Kartieranleitung – 5. Auflage. Hannover, Germany. 438 pp. Bullock, P., Federoff, N., Jongerius, A., Stoops, G., Tursina, T. & Babel, U. 1985. Handbook for soil thin section description. Waine publications. 152 pp. DVWK. 1995. Bodenkundliche Untersuchungen im Felde zur Ermittlung von Kennwerten zur Standortscharakterisierung. Teil I: Ansprache von Böden. DVWK Regeln 129. Bonn, Germany, Wirtschafts- und Verlagsges. Gas und Wasser. ECSC–EEC–EAEC. 1985. Soil map of the European Communities 1:1 000 000. Luxembourg. 124 pp. and paper maps. European Commission Joint Research Centre. 2005. Soil atlas of Europe. FAO. 1978. Report on the agro-ecological zones project. Vol. 1. Methodology and results for Africa. World Soil Resources Report No. 48/1. Rome. FAO. 2002. FAO/UNESCO Digital Soil Map of the World and derived soil properties. Land and Water Digital Media Series #1 rev 1. FAO, Rome. FAO–ISRIC. 1990. Guidelines for profile description. 3rd Edition. Rome. FAO–UNESCO. 1970–1981. Soil map of the world 1:5 000 000. Vol. 2–9. Paris. FAO–UNESCO. 1974. Soil map of the world. Vol. I – legend. Paris. 59 pp. FAO–UNESCO. 1988. Soil map of the world. Revised legend. World Soil Resources Report No. 60. Rome. Fieldes, M. & Perrott, K.W. 1966. The nature of allophane soils: 3. Rapid field and laboratory test for allophane. N. Z. J. Sci., 9: 623–629. International Soil Reference and Information Centre (ISRIC). 2005. Updated global and national soils and terrain digital databases (SOTER). IUSS Working Group WRB. 2006. World reference base for soil resources 2006 – A framework for international classification, correlation and communication. World Soil Resources Reports No. 103. Rome, FAO. Jahn, R. 2004. Research needs and new developments in soil classification and mapping: meeting the changing demands for soil information. Proceedings of International Conference on Innovative Techniques in Soil Survey, pp. 207–222. Cha-Am, Thailand. Meuser, H. 1996. Ein Bestimmungsschlüssel für natürliche und technogene Substrate in Böden städtisch-industrieller Verdichtungsräume. Z. Pflanzenernähr. Bodenk., 159: 305–312. Munsell. 1975. Standard soil color charts. Richards, L.A. 1954. Diagnosis and improvement of saline and alkali soils. Agriculture Handbook No. 60. USDA Rossiter, D.G. 2004. Proposal: classification of urban and industrial soils in the World Reference Base for Soil Resources (WRB). In: Abstracts Eurosoil 2004. Freiburg im Breisgau, Germany.
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Schlichting, E., Blume, H.-P. & Stahr, K. 1995. Bodenkundliches Praktikum. 2nd edition. Berlin, Vienna, Blackwell. 295 pp. Schoeneberger, P.J. Wysocki, D.A, Benham, E.C. & Broderson, W.D. 2002. Field book for describing and sampling soils. Version 2.0. Lincoln, USA, National Soil Survey Center, Natural Resources Conservation Service, USDA. UNEP–ISSS–ISRIC–FAO. 1995. Global and national soils and terrain digital database (SOTER). World Soil Resources Report No. 74 Rev. 1. Rome. United States Department of Agriculture (USDA) Soil Survey Staff. 1975. Soil taxonomy. Agricultural Handbook No. 436. Washington, DC. 754 pp. United States Department of Agriculture (USDA) Soil Survey Staff. 1999. Soil taxonomy, a basic system of soil classification for making and interpreting soil surveys. 2nd edition. Agricultural Handbook No. 436. Washington, DC. 869 pp. United States Department of Agriculture (USDA) Soil Survey Staff. 2003. Keys to soil taxonomy. 9th edition. Washington, DC, Natural Resources Conservation Service, USDA. 332 pp. Van Reeuwijk, L.P. 2006. Procedures for soil analysis. 7th edition. Technical Report 9. Wageningen, Netherlands, ISRIC – World Soil Information.
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Annex 1 Explanation of soil temperature regimes1
The temperature of a soil is one of its important properties. Within limits, temperature controls the possibilities for plant growth and for soil formation. Below freezing point, there is no biotic activity, water no longer moves as a liquid, and, unless there is frost heaving, time stands still for the soil. Between 0 and 5 °C, root growth of most plant species and germination of most seeds are impossible. A horizon as cold as 5 °C is a thermal pan to the roots of most plants. Each pedon has a characteristic temperature regime that can be measured and described. For most practical purposes, the temperature regime can be described by: the mean annual soil temperature; the average seasonal fluctuations from that mean; and the mean warm or cold seasonal temperature gradient within the main rootzone, which is the zone from a depth of 5 to 100 cm.
MEAN ANNUAL SOIL TEMPERATURE Each pedon has a mean annual temperature that is essentially the same in all horizons at all depths in the soil and at depths considerably below the soil. The measured mean annual soil temperature is seldom the same in successive depths at a given location. However, the differences are so small that it seems valid and useful to take a single value as the mean annual temperature of a soil. The mean annual soil temperature is related most closely to the mean annual air temperature, but this relationship is affected to some extent by: the amount and distribution of rain; the amount of snow; the protection provided by shade and by O horizons in forests; the slope aspect and gradient; and irrigation. Other factors, such as soil colour, texture, and content of organic matter, have negligible effects.
FLUCTUATIONS IN SOIL TEMPERATURE The mean annual temperature of a soil is not a single reading but the average of a series of readings. Near the surface, the readings may fluctuate from the mean fully as much as those of the air temperature, especially where there is no insulating cover. The fluctuations occur as daily and annual cycles, which weather events make somewhat irregular in most places. The fluctuations decrease with increasing depth and are ultimately damped out in the substrata
1 Adapted from USDA, 1999.
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in a zone where the temperature is constant and is the same as the mean annual soil temperature.
ESTIMATION OF SOIL TEMPERATURE Soil temperature can often be estimated from climatological data with a precision that is adequate for the present needs of soil surveys. Where it is not possible to make reasonably precise estimates, the measurement of soil temperature need not be a difficult or a time-consuming task. Frequently, the mean annual soil temperature for much of the United States of America is estimated by adding 1 °C to the mean annual air temperature. The mean summer soil temperature at a specific depth can also be estimated. To make this estimate, it is possible to take the average summer temperatures of the upper 100 cm and correct for the temperature-depth gradient by adding or subtracting 0.6 °C for each 10 cm above or below a depth of 50 cm. The mean winter temperature of many mid-latitude soils can be estimated from the difference between the mean annual temperatures and the mean summer temperatures because the differences are of the same magnitude but have opposite signs.
CLASSES OF SOIL TEMPERATURE REGIMES The following is a description of the soil temperature regimes used in defining classes at various categoric levels in the soil taxonomy of the United States of America. PG – Pergelic (Latin per, throughout in time and space, and gelare, to freeze; meaning permanent frost). Soils with a pergelic temperature regime have a mean annual temperature lower than 0 °C. These are soils that have permafrost if they are moist, or dry frost if there is no excess water. CR – Cryic (Greek kryos, coldness; meaning very cold soils). Soils in this temperature regime have a mean annual temperature lower than 8 °C but do not have permafrost. 1. In mineral soils, the mean summer soil temperature (June, July and August in the Northern Hemisphere, and December, January, and February in the Southern Hemisphere) either at a depth of 50 cm from the soil surface or at a densic, lithic or paralithic contact, whichever is shallower, is as follows: a. if the soil is not saturated with water during some part of the summer and: (1) If there is no O horizon: lower than 15 °C; or (2) If there is an O horizon: lower than 8 °C; or b. if the soil is saturated with water during some part of the summer and: (1) If there is no O horizon: lower than 13 °C; or (2) If there is an O horizon or a histic epipedon: lower than 6 °C. 2. In organic soils, the mean annual soil temperature is lower than 6 °C. Cryic soils that have an aquic moisture regime are commonly churned by frost.
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Isofrigid soils could also have a cryic temperature regime. A few with organic materials in the upper part are exceptions. The concepts of the soil temperature regimes described below are used in defining classes of soils in the low categories.
FR – Frigid A soil with a frigid temperature regime is warmer in summer than a soil with a cryic regime. However, its mean annual temperature is lower than 8 °C and the difference between mean summer (June, July and August) and mean winter (December, January and February) soil temperatures is more than 6 °C either at a depth of 50 cm from the soil surface or at a densic, lithic or paralithic contact, whichever is shallower.
IF – Isofrigid The mean annual soil temperature is lower than 8 °C and the mean summer and mean winter soil temperatures differ by less than 6 °C at a depth of 50 cm or at a densic, lithic or paralithic contact, whichever is shallower.
ME – Mesic The mean annual soil temperature is 8 °C or higher but lower than 15 °C, and the difference between mean summer and mean winter soil temperatures is more than 6 °C either at a depth of 50 cm from the soil surface or at a densic, lithic or paralithic contact, whichever is shallower.
IM – Isomesic The mean annual soil temperature is 8 °C or higher but lower than 15 °C and the mean summer and mean winter soil temperatures differ by less than 6 °C at a depth of 50 cm or at a densic, lithic or paralithic contact, whichever is shallower.
TH – Thermic The mean annual soil temperature is 15 °C or higher but lower than 22 °C, and the difference between mean summer and mean winter soil temperatures is more than 6 °C either at a depth of 50 cm from the soil surface or at a densic, lithic or paralithic contact, whichever is shallower.
IT – Isothermic The mean annual soil temperature is 15 °C or higher but lower than 22 °C and the mean summer and mean winter soil temperatures differ by less than 6 °C at a depth of 50 cm or at a densic, lithic or paralithic contact, whichever is shallower.
HT – Hyperthermic The mean annual soil temperature is 22 °C or higher, and the difference between mean summer and mean winter soil temperatures is more than 6 °C at a depth of
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50 cm from the soil surface or at a densic, lithic or paralithic contact, whichever is shallower.
IH – Isohyperthermic The mean annual soil temperature is 22 °C or higher and the mean summer and mean winter soil temperatures differ by less than 6 °C at a depth of 50 cm or at a densic, lithic or paralithic contact, whichever is shallower.
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Annex 2 Explanation of soil moisture regimes1
The term “soil moisture regime” refers to the presence or absence either of groundwater or of water held at a tension of less than 1 500 kPa (pF 4.2) in the soil or in specific horizons during periods of the year. Water held at a tension of 1 500 kPa or more is not available to keep most mesophytic plants alive. The availability of water is also affected by dissolved salts. Where a soil is saturated with water that is too salty to be available to most plants, it is considered salty rather than dry. Consequently, a horizon is considered dry when the moisture tension is 1 500 kPa or more, and it is considered moist when water is held at a tension of less than 1 500 kPa but more than zero. A soil may be continuously moist in some or all horizons either throughout the year or for some part of the year. It may be either moist in winter and dry in summer or the reverse. In the Northern Hemisphere, summer refers to June, July and August, and winter refers to December, January and February.
SIGNIFICANCE TO SOIL CLASSIFICATION The moisture regime of a soil is an important property of the soil as well as a determinant of processes that can occur in the soil. During geological time, there have been significant changes in climate. Soils that could have formed only in a humid climate are now preserved in an arid climate in some areas. Such soils have relict features that reflect the former moisture regime and other features that reflect the present moisture regime. Each of the moisture regimes in the history of a soil is a factor in the genesis of that soil and is the cause of many accessory characteristics. However, most of the accessory characteristics and those most important for interpretations are associated with the present moisture regime, even if the present regime differs widely from some of the earlier. More importantly, the present climate determines use and management of the soil. It is a property of the soil. Furthermore, the moisture regimes of most soils are inferred from the present climate, and small-scale maps can be interpreted in terms of the many accessory characteristics that are common to most of the soils that have a common climate. These characteristics include: the amount, nature and distribution of organic matter; the base status of the soil; and the presence or absence of salts.
1 Adapted from USDA, 1999.
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NORMAL YEARS In the discussions that follow and throughout the keys, the term “normal years” is used. A normal year is defined as a year that has plus or minus one standard deviation of the long-term mean annual precipitation (long term refers to 30 years or more). In addition, the mean monthly precipitation in a normal year must be plus or minus one standard deviation of the long-term monthly precipitation for 8 of the 12 months. Normal years can usually be calculated from the mean annual precipitation. However, when catastrophic events occur during a year, the standard deviations of the monthly means should also be calculated.
ESTIMATION The landscape position of every soil is subject to extremes in climate. While no two years have exactly the same weather conditions, the moisture status of the soil must be characterized by probability. Weather probabilities can be determined from long-term weather records and observations of how each soil responds to weather conditions as modified by its landscape position. A number of methods have been devised to relate soil moisture to meteorological records. To date, all these methods have some shortcomings, even for gently sloping soils that depend primarily on precipitation for their moisture. Dew and fog can add appreciable amounts of moisture to some soils, but quantitative data are rare.
SOIL MOISTURE CONTROL SECTION The intention in defining the soil moisture control section is to facilitate estimation of soil moisture regimes from climate data. The upper boundary of this control section is the depth to which a dry (tension of more than 1 500 kPa, but not air-dry) soil will be moistened by 2.5 cm of water within 24 hours. The lower boundary is the depth to which a dry soil will be moistened by 7.5 cm of water within 48 hours. These depths do not include the depth of moistening along any cracks or animal burrows that are open to the surface. The boundaries for the soil moisture control section correspond to the rooting depths for many crops. However, there are natural plant communities that have their roots either above or below the control section. Attempts are currently being made to improve the parameters of the soil moisture control section. If 7.5 cm of water moistens the soil to a densic, lithic, paralithic or petroferric contact or to a petrocalcic or petrogypsic horizon or a duripan, the contact or the upper boundary of the cemented horizon constitutes the lower boundary of the soil moisture control section. The concept of the soil moisture control section does not apply well to the cracking clays, because these clays remoisten from both the surface and the bases of the cracks. The soil moisture patterns of these soils are defined in terms of the pattern of cracking over time. If moistening occurs unevenly, the weighted average depth of moistening in a pedon is used for the limits of the moisture control section.
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The moisture control section of a soil extends approximately: ¾from 10 to 30 cm below the soil surface if the particle-size class of the soil is fine-loamy (> 15 percent particles 0.1–75 mm and 18–35 percent clay), coarse-silty (< 15 percent particles 0.1–75 mm and < 18 percent clay in fine earth), fine-silty (< 15 percent particles 0.1–75 mm and 18–35 percent clay in fine earth), or clayey (> 35 percent clay); ¾from 20 to 60 cm if the particle-size class is coarse-loamy silty (>15 percent particles 0.1–75 mm and < 18 percent clay in fine earth); ¾from 30 to 90 cm if the particle-size class is sandy (texture of sand or loamy sand). If the soil contains rock and pararock fragments that do not absorb and release water, the limits of the moisture control section are deeper. The limits of the soil moisture control section are affected not only by the particle-size class but also by differences in soil structure or pore-size distribution or by other factors that influence the movement and retention of water in the soil.
CLASSES OF SOIL MOISTURE REGIMES The soil moisture regimes are defined in terms of the level of groundwater and in terms of the seasonal presence or absence of water held at a tension of less than 1 500 kPa in the moisture control section. It is assumed in the definitions that the soil supports whatever vegetation it is capable of supporting, i.e., crops, grass or native vegetation, and that the amount of stored moisture is not being increased by irrigation or fallowing. These cultural practices affect the soil moisture conditions as long as they continued.
AQ – Aquic moisture regime The aquic (Latin aqua, water) moisture regime is a reducing regime in a soil that is virtually free of dissolved oxygen because it is saturated by water. Some soils are saturated with water at times while dissolved oxygen is present, either because the water is moving or because the environment is unfavourable for micro-organisms (e.g. where the temperature is less than 1 °C); such a regime is not considered aquic. It is not known how long a soil must be saturated before it is said to have an aquic moisture regime. However, the duration must be at least a few days, because it is implicit in the concept that dissolved oxygen is virtually absent.
PQ – Peraquic moisture regime Very commonly, the level of groundwater fluctuates with the seasons. However, there are soils in which the groundwater is always at or very close to the surface. Examples are soils in tidal marshes or in closed, landlocked depressions fed by perennial streams. Such soils are considered to have a peraquic moisture regime.
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AR – Aridic and TO – torric (Latin aridus, dry, and torridus, hot and dry) moisture regimes These terms are used for the same moisture regime but in different categories of the taxonomy. In the aridic (torric) moisture regime, the moisture control section in normal years is both: ¾dry in all parts for more than half on the cumulative days per year when the soil temperature at a depth of 50 cm from the soil surface is above 5 °C; ¾moist in some or all parts for less than 90 consecutive days when the soil temperature at a depth of 50 cm is above 8 °C. Soils that have an aridic (torric) moisture regime normally occur in areas of arid climates. A few are in areas of semi-arid climates and either have physical properties that keep them dry, such as a crusty surface that virtually precludes the infiltration of water, or are on steep slopes where runoff is high. There is little or no leaching in this moisture regime, and soluble salts accumulate in the soils if there is a source.
UD – Udic moisture regime The udic (Latin udus, humid) moisture regime is one in which the soil moisture control section is not dry in any part for as long as 90 cumulative days in normal years. Where the mean annual soil temperature is lower than 22 °C and where the mean winter and mean summer soil temperatures at depth of 50 cm from the soil surface differ by 6 °C or more, the soil moisture control section in normal years is dry in all parts for less than 45 consecutive in the 4 months following the summer solstice. In addition, the udic moisture regime requires, except for short periods, a three-phase system, solid–liquid–gas, in part or all of the soil moisture control section when the soil temperature is above 5 °C. The udic moisture regime is common to the soils of humid climates that: have well-distributed rainfall; have enough rain in summer so that the amount of stored moisture plus rainfall is approximately equal to, or exceeds, the amount of evapotranspiration; or have adequate winter rains to recharge the soils and cool, foggy summers, as in coastal areas. Water moves downwards though the soils at some time in normal years.
PU – Perudic moisture regime (Latin per, throughout in time, and udus, humid) In climates where precipitation exceeds evapotranspiration in all months of normal years, the moisture tension rarely reaches 100 kPa (pF 3) in the soil moisture control section, although there are occasional brief periods when some stored moisture is used. The water moves through the soil in all months when it is not frozen. Such an extremely wet moisture regime is called perudic.
US – Ustic moisture regime The ustic (Latin ustus, burnt; implying dryness) moisture regime is intermediate between the aridic regime and the udic regime. Its concept is one of moisture
809 Annex 2 – Explanation of soil moisture regimes 95
that is limited but is present at a time when conditions are suitable for plant growth. The concept of the ustic moisture regime is not applied to soils that have permafrost or a cryic soil temperature regime (defined above). If the mean annual soil temperature is 22 °C or higher or if the mean summer and winter soil temperatures differ by less than 6 °C at a depth of 50 cm below the soil surface, the soil moisture control section in areas of the ustic moisture regime is dry in some or all parts for 90 or more cumulative days in normal years. However, it is moist in some part either for more than 180 cumulative days per year or for 90 or more consecutive days. If the mean annual soil temperature is lower than 22 °C and if the mean summer and winter soil temperatures differ by 6 °C or more at a depth of 50 cm from the soil surface, the soil moisture control section in areas of the ustic moisture regime is dry in some or all parts for 90 or more cumulative days in normal years, but it is not dry in all parts for more than half of the cumulative days when the soil temperature at a depth of 50 cm is higher than 5 °C. If in normal years the moisture control section is moist in all parts for 45 or more consecutive days in the 4 months following the winter solstice, the moisture control section is dry in all parts for less than 45 consecutive days in the 4 months following the summer solstice. In tropical and subtropical regions that have a monsoon climate with either one or two dry seasons, summer and winter seasons have little meaning. In such regions, the moisture regime is ustic if there is at least one rainy season of three months or more. In temperate regions of subhumid or semi-arid climates, the rainy seasons are usually spring and summer or spring and autumn, but never winter. Native plants are mainly annuals or plants that have a dormant period while the soil is dry.
XE – Xeric moisture regime The xeric (Greek xeros, dry) moisture regime is the typical moisture regime in areas of Mediterranean climates, where winters are moist and cool and summers are warm and dry. The moisture, which falls during the winter, when potential evapotranspiration is at a minimum, is particularly effective for leaching. In areas of a xeric moisture regime, the soil moisture control section, in normal years, is dry in all parts for 45 or more consecutive days in the 4 months following the summer solstice and moist in all parts for 45 or more consecutive days in the 4 months following the winter solstice. Moreover, in normal years, the moisture control section is moist in some part for more than half of the cumulative days per year when the soil temperature at a depth of 50 cm from the soil surface is higher than 6 °C or for 90 or more consecutive days when the soil temperature at a depth of 50 cm is higher than 8 °C. The mean annual soil temperature is lower than 22 °C, and the mean summer and mean winter soil temperatures differ by 6 °C or more either at a depth of 50 cm from the soil surface or at a densic, lithic or paralithic contact if shallower.
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Annex 3 Equipment necessary for field work
0 cm Map of topography (at least 1:25 000), geology (geomorphology, land use, 1 vegetation where available) Global positioning system unit, compass 2 Guideline for soil description Guideline for soil classification 3
Field book, reading form 4 Munsell soil color charts
5 Shovel, spade, pick-axe, auger and hammer Field pH-/conductometer, standard solutions Box with: 6 ¾ pocket rule ¾ knife, palette-knife 7 ¾ hand lens (×10) ¾ platinum electrodes (redox measurement) 8 ¾ bottle with tap water ¾ bottle with aqua dest 9 ¾ bottle with 1 M KCl or 0.01 M CaCl2 solution (25 ml per pH measurement) ¾ five transparent plastic cups with marks for 8 cm3 soil (~ 10 g) and 25 ml water, per pH or EC measurement 10 ¾ drop flask with 10 percent HCl (~ 50 ml) ¾ drop flask with phenolphthalein pH indicator (8.2...9.8) solution (~ 30 ml) 11 ¾ drop flask with 1 M NaF adjusted to pH 7.5 (~ 30 ml) ¾ drop flask with 0.2 percent (M/V) _,_-dipyridyl solution in 10 percent 12 (V/V) acetic acid solution (~ 50 ml).
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812 813 United Nations Economic Commission for Europe Convention on Long-range Transboundary Air Pollution
International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests)
MANUAL
on
methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests
Part XVI Quality Assurance and Control in Laboratories
updated: 05/2010
814
Prepared by: ICP Forests Working Group on QA /QC in Laboratories (N. König, A. Kowalska, Giorgio Brunialti, Marco Ferretti, N. Clarke, N. Cools, J. Derome, K. Derome, B. De Vos, A. Fuerst, T.Jakovljevič, A. Marchetto, R. Mosello, P. O’Dea, G. A. Tartari, E. Ulrich)
König N, Kowalska A, Brunialti G, Ferretti M, Clarke N, Cools N, Derome J, Derome K, De Vos B, Fuerst A, Jakovljevič T, Marchetto A, Mosello R, O’Dea P, Tartari GA, Ulrich E, 2010: Quality Assurance and Control in Laboratories. 53 pp. Part XVI. In: Manual on methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests. UNECE, ICP Forests Programme Co-ordinating Centre, Hamburg. ISBN: 978-3-926301-03-1. [http://www.icp-forests.org/Manual.htm] The compilation of this Manual part in the years 2009/2010 was co-financed by the European Commission under the LIFE Regulation. All rights reserved. Reproduction and dissemination of material in this information product for educational or other non-commercial purposes are authorized without any prior written permission from the copyright holders provided the source is fully acknowledged. Reproduction of material in this information product for resale or other commercial purposes is prohibited without written permission of the copyright holder. Application for such permission should be addressed to: vTI - Institute for World Forestry Leuschnerstrasse 91 21031 Hamburg, Germany [email protected]
Hamburg, 2010
815
CONTENTS
1. INTRODUCTION...... 5
2. SCOPE AND APPLICATION...... 5
3. QUALITY ASSURANCE AND CONTROL TOOLS...... 6
3.1 USE OF REFERENCE MATERIALS ...... 6 3.1.1 Reference material for water analysis (deposition and soil solution)...... 6 3.1.2 Reference material for foliar analysis ...... 7 3.1.3 Reference material for soil analysis...... 7
3.2 USE OF CONTROL CHARTS ...... 8 3.2.1 Use of control charts for LRM or laboratory control standards ...... 9 3.2.2 Use of control charts for blanks...... 10 3.2.3 Detection and quantification limits...... 11
3.3 CHECKING THE ANALYTICAL DATA ...... 13 3.3.1 Checking water sample results ...... 13 3.3.2 Checking organic and mineral soil samples results ...... 24 3.3.3 Check of analytical results for foliar and litterfall samples...... 29 3.3.4 Analyses in duplicate...... 32 3.3.5 Avoidance of contamination ...... 32
3.4 INTER-LABORATORY QUALITY ASSURANCE...... 34 3.4.1 Ring tests and ring test limits...... 35 3.4.2 Exchange of knowledge and expertise amongst laboratories...... 42
3.5 QUALITY INDICATORS ...... 43 3.5.1 Percentage of the results of a ring test within tolerable limits...... 43 3.5.2 Percentage of the results of a ring test with a precision <10%...... 43 3.5.3 Mean percentage of parameters for which laboratories use control charts...... 43
3.6 QUALITY REPORTS...... 44
4. REFERENCES ...... 44
5. ANNEXES...... 47
5.1 EXCEL WORKSHEET FOR ION BALANCE (WITH AND WITHOUT DOC CORRECTION), CONDUCTIVITY, N BALANCE AND
NA/CL RATIO CHECKS...... 47
5.2 EXCEL WORKSHEET FOR CONTROL CHARTS...... 47
5.3 LIST OF COMMERCIALLY AVAILABLE REFERENCE MATERIALS ...... 48
5.4 DEFINITIONS AND TERMINOLOGY...... 49
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1. Introduction
Chemical analyses are an essential part of monitoring activities related to observations and measurements of nutrients and pollutants fluxes in forest ecosystems. The value of data collected under the framework of the ICP-Forests programme depends to a great extent on the quality of the analytical work carried out in supporting laboratories across Europe. To gain full comparability of the spatial and temporal variability in the data, every effort must be taken to ensure accuracy of the analytical measurements. To that end, considerable efforts have been made over the last number of years to improve the quality of laboratory analyses in the various monitoring programmes within the framework of the ICP Forests programme. The Soil & Soil Solution, Deposition and Foliage & Litterfall expert panels have carried out a number of ring tests and held extensive discussions on harmonising analytical methodology, including the most appropriate quality control (QC) and quality assurance (QA) to be employed by participating laboratories. An expert panel sub-group, 'Working Group on QA/QC in Laboratories', has extended its remit from optimising the quality control of water analyses to encompass all forms of laboratory analysis, and now also includes experts in the fields of soil, foliage and litterfall. Presented quality assurance and control tools remain in line with the overall QA approach within the ICP-Forests, as outlined in the Part III of the Manual.
2. Scope and application
This paper presents all the QC methods that have been devised for the relevant fields of analytical chemistry. The aim is to provide those laboratories carrying out analyses of water, soil solution, soil, foliage and litterfall within the ICP Forests programme with a complete overview of the QC options that can be applied in their laboratories. The QA programme in each laboratory should be based on both: internal and external quality control. Among the range of internal control methods that can be employed, the use of reference materials is highly recommended (Chapter 3.1) as an extremely valuable tool to ensure accuracy of analytical results. Although the use of Certified Reference Materials can be limited by expense and availability in large quantities alternative Reference Materials, such as National or Local Reference Materials can be used on a routine basis to confirm the analytical methods accuracy and precision over time. The variation and the quality of the analytical results can be controlled with the use of control charts. The different types of control charts available, their construction and application are described in Chapter 3.2. Analytical data must be validated prior to data submission to confirm the correctness of analyses and exclude the risk of errors. A wide range of data consistency checks are detailed depending on the type of matrix analysed (Chapter 3.3, 3.3.1-3.3.3), based on the relationship between the chemical components and/or chemical and physical properties of the samples. Participation by laboratories in external inter-calibration exercises plays an integral role in the laboratory’s QA programme (Chapter 3.4). Otherwise known as ‘ring tests’, they are carried out on a periodic basis and assess the performance of the participating laboratories as well as help to ensure the comparability of the data produced by different laboratories over time. Laboratories encountering difficulties with analytical methodology and/or associated QA/QC programmes are encouraged to take full advantage of the range of proposals contained within this document, which include the exchange of analytical expertise, and experiences between laboratories. version 5/2010 5
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Evaluation of the quality performance of the participating laboratories within ICP Forests will be conducted through the use of quality indicators outlined in Chapter 3.5. Information gathered on the laboratories quality assurance processes/activities, will be linked via quality reports, with the submission of data to ICP Forests each year.
3. Quality assurance and control tools
3.1 Use of reference materials Within the ICP-Forests programme the use of control charts for each variable and matrix is mandatory. In order to produce these control charts, a reference material is necessary. There are two types of reference material: 1. Reference Materials (RM): a material or substance, one or more of whose property values are sufficiently homogeneous and well established to be used for the calibration of an apparatus, the assessment of a measurement method, or for assigning values to materials (ISO Guide 30, 1992) 2. Certified Reference Materials (CRM): Reference material, accompanied by a certificate, one or more of whose property values are certified by a procedure, which establishes its traceability to an accurate realisation of the units in which the property values are expressed, and for which each certified value is accompanied by an uncertainty at a stated level of confidence (ISO Guide 30, 1992). The CRM can be of national or international origin. A list of commercially available CRMs is given in Annex 5.3. Reference materials are available in a range of types and prices. CRMs are expensive and should be used only when really needed: e.g. calibration, method validation, measurement verification, evaluating measurement uncertainty (Nordtest Report 537, 2003), and for training purposes. In many cases, however, the concentrations are not within the ranges encountered in daily practice. National Reference Materials are, in many cases, easier to acquire and are often not as expensive as CRMs. They are usually issued by national laboratories, and are extremely useful for ensuring laboratory quality within a country. Furthermore, laboratories must use matrix-matched control samples of demonstrated stability to demonstrate internal consistency over time, e.g. through control charts. The analyte concentrations of these samples do not need to be accurately known or traceable. However, traceability would be a bonus. Here, again, CRMs or ring test samples can be used. The Local Reference Materials (LRMs) are prepared by the laboratory itself for routine use and can be easily and cheaply prepared in large quantities. They can often also be prepared within the concentration ranges for the more important parameters. These LRMs are extremely important for QA/QC activities, mainly for use in control charts (see Chapter 3.2), if there is a need to maintain a constant (stable) quality over a longtime scale. The following reference materials can be used in each field of interest:
3.1.1 Reference material for water analysis (deposition and soil solution) One common approach is to use natural samples that are preserved with stabilising agents (e.g. low chloroform concentrations), after first ensuring that their use does not cause interferences in the analytical methods or has an adverse effect on other activities performed in the laboratory. The use of natural samples makes it possible to have concentrations close to those normally measured. It is advisable to use two standards for each type of analysis, one of medium-low and
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one of medium-high concentrations, in relation to the range normally analysed. The stability of LRMs should be tested; their stability for individual ion species may vary. One very cheap method for preparing an LRM is to buy mineral water that has chemical characteristics close to the range normally measured. Before you can use an LRM, however, you first have to validate your method with a CRM. You should run your LRM together with the CRM or a ring test sample so as to determine the conventional true value. For deposition samples, mineral water derived from volcanic bedrock has very similar concentrations. For soil solution samples, a specific type of mineral water has to be selected in accordance with the prevailing soil types in the monitoring network. The advantage of using mineral water is that they are relatively stable over time as long as the bottles of the same batch are stored in a dark place. However, mineral water does not contain dissolved organic carbon (DOC) in a form similar to that occurring in either deposition or soil solution samples.
3.1.2 Reference material for foliar analysis The matrix properties and the analyte concentrations of the reference material should be similar to those of the samples from the regional/national network. As there is only a limited number of certified forest-tree foliage reference material available worldwide, agricultural plant material with similar matrix and analyte concentrations, e.g. flour, hay, cabbage, olive leaves, apple leaves, can be used as an acceptable substitute. However, check the analyte concentrations before placing the order. (A list of commercially available CRM`s is given in Annex 5.3). “Old” ring test samples are also stable enough and extensively analysed for use as reference material in method validation. One good cheap method for producing a high quality LRM is to prepare foliage material for use as a ring test sample. In the ring tests, the Forest Foliar Co-ordinating Centre (FFCC) always utilises dried, powdered foliage samples from one type of tree and leaf or a homogenized litterfall sample. Therefore, the laboratory should initially separate the needles/leaves from the branches and dry, mill and homogenise the material (dry weight min. 4-5 kg) prior to dispatch to the FFCC (http://www.ffcc.at/) The FFCC homogenizes the sample again, divides it up and uses it in one of the subsequent ring tests. The advantage for the laboratory is in having a large amount of reference material with a similar element concentration as their normal samples and known accuracy of the mean concentration.
3.1.3 Reference material for soil analysis
3.1.3.1 Preparation of local reference material for soils Due to the type of soil samples and the nature of the two-step analysis, LRM samples are needed for both the solid phase (to control the quality of digestion) and the liquid phase (to control the quality of the chemical analyses). solid phase: Take several large (10 to 50 kg) samples from one site (organic and mineral, preferably by horizon). Dry all the sampled material and homogenise the samples several times to ensure a uniform homogeneous sample. Split or riffle each sample into several parts and store in a cool, dry place. It may be worthwhile preparing several sets of the individual soil types and concentration ranges occurring in the country (e.g. one for clay soils in the coastal area with high sea salt concentrations, and one for sandy soil from an inland site).
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liquid phase: After digestion of larger amounts of the solid phase LRM, store the solution (liquid phase) in a cool, dark place. In general, no control with high analyte concentrations is necessary because the errors are normally associated with lower concentrations. Solutions with excessively high concentrations often have to be diluted in order to fit within the ranges for which the analysers have been calibrated. The amount of LRM has to be large enough to be used for an extended period of time (preferably up to one year). The amount needed annually will depend on the type of analytical equipment and methods used by the laboratory. The sample should be stored in such a way that no or minimal changes occur over time.
3.1.3.2 Calibration of local reference material for soils After the preparation of the LRM, a test run has to be performed with correctly calibrated equipment. A number of replicates (e.g. 5 for the solid and 30 for the liquid phase) have to be analysed for all relevant parameters, and at least one (but preferably more) national or international reference samples. The absolute accuracy is determined for each parameter on the latter samples. The standard deviation (SD) calculated from the results of analysis of the LRM should be as small as possible. The results of the first test run should be treated according to the ISO standard 8258 (1993, Shewhart control charts). The mean value of the parameters for the LRM is of less importance, but it should be within the same range as the values of the samples that will be subsequently analysed. Each parameter now has its own SD, which allows evaluation of the parameters and the relevance of the analysis by the method in question. If the SD is significantly larger than the expected values, then the relevance of analysing the parameter by the selected method is low. Other methods/equipment may have to be used to analyse the parameter within an acceptable range. This procedure should be repeated whenever equipment is changed, important components are replaced, or when temporal trends appear in the results. The absolute values obtained from the national and international reference material are extremely importance in the former case.
3.1.3.3 C. Use of local reference material for soils After successful calibration, a systematic re-analysis of the LRM (liquid phase) is included in every batch or series of samples. Depending on the number of samples to be analysed and the methods and equipment used, this could be in the range of one LRM per 10 to 30 real samples to be analysed. For the solid phase (digestion and analysis) this could be reduced to one LRM per 30 to 50 samples to be analysed. The results of the repeated analysis of the LRM permit evaluation of the stability of the method/equipment over time. Therefore, it is strongly recommended to plot on a graph the LRM result of every analysis over time (see ISO 8258, 1993 and Chapter 3.2).
3.2 Use of control charts Within the ICP-Forests programme the use of control charts for each parameter and matrix is mandatory. Control charts form an important practical aspect of internal QC in the laboratory. Using reference materials (see Chapter 3.1) the quality of the method can be checked immediately, while control charts are a useful tool for checking the quality and the variation in quality over a longer time scale. The laboratory runs control samples together with the real samples in an analytical batch
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and, immediately after the run is completed, the control values are plotted on a control chart. There are various types of control chart available (for details see the ISO 8258, 1993). The most commonly used control charts are the mean chart and range chart for laboratory control standards, and the blank chart for background or reagent blank results. In addition, the control charts can be used for calibration, method validation and comparison, estimation of measurement uncertainty and limit of detection, checking the drift of equipment, comparison or qualification of laboratory personnel, and evaluation of proficiency tests. For more information about the use of control charts see Nordtest report TR 569, 2007.
3.2.1 Use of control charts for LRM or laboratory control standards Means chart (X-chart). The main aim of the means chart is to check the repeatability of the measurements in every batch of analyses. It is constructed from the average and standard deviations of a standard, determined from a solution of one or more analyte(s), or a natural sample, that is sufficiently stabilised to keep the concentrations constant over time for at least 2-4 months. In the case of deposition samples, the choice of preservative (e.g. inorganic acids or chloroform) is determined by the analyte of interest and the conditions under which the analyses are carried out. It is advisable to use more than one control chart, at different concentration levels for each analyte. The means chart is prepared on the basis of the first 20 to 25 measurements used to calculate the mean concentration (Xm) and the standard deviation (s). These variables are used to evaluate the upper and lower warning levels (UWL, LWL) and the upper and lower control levels (UCL, LCL). It is a common practice to use ± 2s and ± 3s limits for the warning limit (WL) and control limit (CL), respectively (Figure 3.2.1a). For variables with a non-normal distribution, transformation to a normal distribution may be necessary. Assuming that s is correctly estimated, 95% of the measurements should fall within the range of Xm±2s (WL) and 99% in the range of Xm±3s (CL). In long-term routine analyses, on the other hand, UWL and LWL may be chosen by the analyst on the basis of experience with previous control charts or according to specific goals that are to be reached in the analyses. The means chart can also incorporate a target or nominal value of the analyte in the case of reference material with the reported concentration. The target control limits may also be used, and the laboratory results then be compared with these values. If measurement uncertainty is determined for an analyte as a part of method validation, this value can be added to a means chart. Measurement uncertainty limits in the chart should lie between the warning and control limits (2s and 3s), in most case nearer the warning limit. The results of a control sample should not exceed the measurement uncertainty limits and, in the case of a synthetic control sample, they should remain between these limits. A target or nominal value can also be used with the measurement uncertainty limits. Because measurement uncertainty is proportional to the concentration of the analyte, different measurement uncertainty limits should be used for different control charts of the same analyte. With this type of x-chart it is possible to check that the set measurement uncertainty is achievable in the course of time. Every batch of analyses should include one or more measurements of the standard for the control chart. This measurement is plotted on the control chart: if a measurement exceeds the CL, the analysis must be repeated immediately. If the repeat is within the CL, then the analysis can be continued; if it exceeds the CL, the analysis should be stopped and the problem rectified. In regard to the WL: if two out of three successive points exceed the WL, then an additional standard should be analysed. If the concentration is less than the WL, the analysis can be continued; if it exceeds the WL, then the analysis should be stopped and the problem rectified.
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Figure 3.2.1a: Example of a control chart using mean concentrations. Mean concentration, LWL, UWL lower, upper warning limit; LCL, UCL lower, upper control limit, calculated on the basis of experience with previous control charts (R.S.D. = 3 %).
Range chart (R chart). The difference between two (or more) determinations on the same sample can also be described on a graph. This R chart is used for checking the repeatability of the analysis, usually of duplicate determinations. As the range is normally proportional to the sample concentration, it will therefore be more appropriate to use a control chart where the control value is the relative range r %.
3.2.2 Use of control charts for blanks Blank chart. A blank is defined as a solution of the purest available water that contains all the reagents used for the analysis, but not the analyte. The solution should be subjected to all the steps of the analysis (filtration, digestion, addition of reagents) up until the final measurement. The blank signal then indicates the sum of the analyte released in the different phases of the process, and a check must be made in order to exclude the possibility of occasional contamination. An example of a blank chart is shown in Figure 3.2.2a. The chart makes it possible to compare the blank values obtained in different batches of analyses at different times; an abnormally high blank value indicates the presence of contaminants at some stage of the process. The upper limit of acceptance is chosen by the analyst, either based on a previous set of analyses (e.g. two times the mean values of the blank absorbance) or on the dispersion of values around the mean.
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Figure 3.2.2a: Example of a blank chart
The standard deviation (sb) of the blanks makes it possible to determine the detection limit (LOD) and the quantification limit (LOQ) of the analytical method. The LOD in most instrumental methods is based on the relationship between the gross analyte signal St, the field blank Sb, and the variability in the field blank (sb). The limit of detection and quantification may be defined by the extent to which the gross signal exceeds Sb:
LOD = St - Sb Kd sb
LOQ = St - Sb Kq sb
Recommended values for Kd and Kq are 3 and 10, respectively (Analytical Methods Committee, 1987, Currie, L.A. 1999b).
3.2.3 Detection and quantification limits Detection and quantification capabilities are fundamental performance characteristics of any chemical measurement process (Currie, 1999a). For each matrix (soil, water, foliage) and each analytical method, the limit of detection (LOD) and quantification (LOQ) should be determined by each laboratory. The limit of detection (LOD) is the smallest measure, xL, that can be detected with reasonable certainty for a given analytical procedure.
The value of xL is given by the equation:
xL = xbi + Ksbi where xbi is the mean of n blank measurements, sbi is the standard deviation of n blank measurements, and K is a numerical factor chosen according to the confidence level desired (IUPAC, 1997). For LOD, this K factor is commonly set at 3 (see also Kd in Chapter 3.2.2). The LOD is the concentration at which we can decide whether an element is present or not. It is the point where we can just distinguish a signal from the background (Thomsen et al., 2003). It is recommended that the number of blank measurements (n) is higher than 30, preferably determined under within-lab reproducibility conditions (e.g. different operators, different runs on different days). version 5/2010 11
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The limit of quantification (LOQ), also referred to as the quantitation limit, is generally agreed to begin at a concentration equal to 10 standard deviations of the blank (Kq = 10). Therefore, LOQ is 3.3 times LOD. Quantitatively, the relative standard deviation (RSD) of repeated measures is 10% at the LOQ, and 33% at the LOD (Thomsen et al., 2003). This is in fact a statistical simplification of the uncertainty problem near the lower measurements limits, as explained by Currie (1999b), but in practice it is a useful approximation.
Table 3.2.3a: IUPAC recommendations for uncertainty associated with limits of detection and quantification (after Thomsen et al., 2003). Absolute SD Relative SD Limit of detection LOD 3 σ 33% Limit of quantification LOQ 10 σ 10%
Similar results can also be obtained using the standard deviation of the signal of the lowest calibration standard, instead of the standard deviation of the signal of blank samples. This method should be used in particular when the signal of blank samples is very low, as in the case of ion chromatography. A further possibility is the use of the Hubaux-Vox method for calculating LOD from the error associated to the calibration regression. A distinction should be made between instrument detection/quantification limits and method (or matrix) detection limits. Generally, instrument detection limits (IDLs) are based on a clean matrix. Method/matrix detection limits (MDL) consider real-life matrices such as soil, organic matter and rainwater. Spectroscopists commonly accept that the MDL can be anywhere from about two to five times greater than the IDL. Therefore, labs should clearly mention whether the reported limits are instrument or matrix detection limits. In the case of environmental research, MDLs are more meaningful than IDLs. Measurement precision and concentration (or content) are often clearly related, as shown in Figure 3.2.3a. Generally, as the concentration or content of the analyte decreases, the precision for determination, as expressed in the relative standard deviation increases. When empirically precision data are gathered for each concentration or content level, a graph may be constructed as in Figure 3.2.3a. Each data point represents the RSD of 8 to 20 replicate measurements per level. When a curve is fitted with a suitable equation (e.g. y = a x -b), the limits of detection and quantification may be estimated from this equation by determining the limits at the RSD values of 30% and 10%, respectively. These limits are illustrated in Figure 3.2.3a, whereby total N can be reliably determined in this example at concentrations above the LOQ, whereas determination becomes highly uncertain between the LOD and LOQ. The curve can be constructed using the standard deviation obtained from control charts at different concentration. When the matrix effect is negligible, the standard deviation of the signal of the calibration standards can also be used. An example of application of the LOD and LOQ estimation method for the determination of carbon by the Walkley-Black method in forest soils can be found in De Vos et al. (2007). This empirical method is time-consuming and laborious. However, it immediately shows the matrix detection and quantification limits for real-life samples under specific laboratory conditions.
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60
RSD = 4.8316 * N (-0.5835)
deviation (RSD) 40
20 LOD = 0.044 LOQ = 0.28 = LOQ
Relative standard 0 0.00.51.01.52.0 Total N content (g/kg)
Figure 3.2.3a: Relationship between measurement precision (RSD) and N concentration in a test mineral soil sample.
3.3 Checking the analytical data
3.3.1 Checking water sample results The analytes present in deposition and soil water samples and in soil extracts are mainly in ionic form. This enables the use of at least two checks on the consistency of the analysis results obtained for individual samples: i.e. the calculation of the ion balance, and comparison of the measured conductivity with the conductivity calculated from the sum of each ion. A third consistency test, which is only valid for deposition samples, employs the ratio between the Na+ and Cl- concentrations, which should normally be relatively close to the value in seawater. A fourth check, aimed at identifying analytical errors, is based on the relationship between the different forms of nitrogen analysed. Other statistical procedures that employ the relationship between the equivalent sum of ions (cations, anions) and conductivity can be applied to the datasets. These are based on the relative similarity of the ratio between certain ions in deposition + - 2- - samples, due to their common origin (e.g. Na and Cl from sea spray, SO4 and NO3 from combustion processes, Ca++ and alkalinity from soil dust). However, these methods require a relatively large set of data for the same type of precipitation before they can be applied to the results of single analyses in order to identify outlier values. Examples of the application of these checks on sets of data from different sites in Europe have been reported by Mosello et al. (2005, 2008). Most of the calculations needed to use the validation check, starting from concentration values, can be simplified by using a worksheet file similar to the one given on the ICP Forests web site (http://www.icp-forests.org/DocsQualLab/AnalyticalDataValidation.xls; see also Chapter 5.1). version 5/2010 13
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3.3.1.1 Ion balance 3.3.1.1.1 Ion balance without DOC Each laboratory performs checks on the chemical analyses by calculating the ion balance (for bulk open field and wet only deposition) and comparing the measured and calculated conductivity (for bulk open field [BOF] and wet only deposition, throughfall [THF] and stemflow [STF]) values in order to validate the results. However, these checks are not always applicable to soil water samples due to the presence of aluminium and other metals as various ionic species, especially at a pH < 5 (see Chapter 3.3.1.1.3). If the threshold values of these checks are exceeded, then the analyses must be repeated. If the result is confirmed but the threshold values are still exceeded, then the results must be accepted. The ion balance is based on the equivalent concentration of anions vs. the concentration of cations (Σ Cat vs. Σ An):
++ ++ + + + + Σ Cat = [Ca ] + [Mg ] + [Na ] + [K ] + [NH4 ] + [H ]
------Σ An = [HCO 3] + [SO 4] + [NO 3] + [Cl ] + [Org ] The contribution of fluoride to the ionic balance is normally insignificant. The limit of acceptable errors varies according to the total ionic concentration and the type of solution. The percentage difference (PD) is defined as: PD = 100 * (Σ Cat –Σ An)/(0.5*(Σ Cat + Σ An)) The limits adopted in the ICP Forests/EU Forest Focus programmes are given in Table 3.3.1.1.1°
Table 3.3.1.1.1a: Acceptance threshold values in data validation based on ion balance and conductivity (see definition of CD [the percentage difference between measured and calculated conductivity] in Chapter 3.3.1.2). Conductivity (25 °C) PD CD <10 µS cm-1 ±20% ±30% <20 µS cm-1 ±20% ±20% >20 µS cm-1 ±10% ±10% The conversion factors required to transform the units used in the ICP Forests Manual Part XIV (Deposition) into μeq L-1 are given in Table 3.3.1.1.1b.
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Table 3.3.1.1.1b: The conversion factors used in converting the concentrations used in the ICP Forests Deposition Monitoring Programme to μeq L-1, and the values of equivalent ionic conductivity at infinite dilution. Unit Conversion Equivalent Equivalent (ICPF standard) factor to conductance at conductance at µeq L-1 20°C 25°C kS cm2 eq-1 kS cm2 eq-1 pH Unit 10(6-pH) 0.3151 0.3500 Ammonium mg N L-1 71.39 0.0670 0.0735 Calcium mg L-1 49.9 0.0543 0.0595 Magnesium mg L-1 82.24 0.0486 0.0531 Sodium mg L-1 43.48 0.0459 0.0501 Potassium mg L-1 25.28 0.0670 0.0735 Alkalinity µeq L-1 1 0.0394 0.0445 Sulphate mg S L-1 62.37 0.0712 0.0800 Nitrate mg N L-1 71.39 0.0636 0.0714 Chloride mg L-1 28.2 0.0680 0.0764 Bicarbonate is calculated from total alkalinity (Gran’s alkalinity) in relation to pH, assuming that total alkalinity is determined only by inorganic carbon species, protons and hydroxide:
+ - - 2- TAlk = -[H ] + [OH ] + [HCO3 ] + [CO3 ] This definition is not completely correct in the case of high organic carbon concentrations (DOC > 5 mg C L-1), and in the presence of metals (Al, Fe, Mn etc.) that may contribute to alkalinity or to the cation concentrations (see Chapters 3.3.1.1.2 and 3.3.1.1.3). This sets limits on the use of the ion balance check in validating the analyses for certain types of solution, as summarised in Table 3.3.1.1.1c.
Table 3.3.1.1.1c: Applicability of the validation tests for different types of solution. Ion balance Ion balance Conductivity Na/Cl ratio N test DOC corrected Bulk open field Y Y Y Y Y Wet only Y Y Y Y Y Throughfall N(3) Y Y Y Y Stemflow N(3) Y Y Y Y Soil water N(3) N(4) Y(2) N Y Surface water Y(1) Y Y N Y (1) If DOC <5 mg C L-1 and negligible metal concentrations (2) If metal concentrations are negligible. (3) see chapter 3.3.1.1.2 (4) see chapter 3.3.1.1.3 Examples of comparisons between Σ Cat and Σ An are given in Figure 3.3.1.1.1a for different types of solution. The departure from zero of the ion balance for different types of deposition sample is shown, illustrating the failure of the check in the case of Throughfall (THR) and Stemflow (STF) samples.
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300
250 Bulk open field Throughfall 200 Stemflow
150
100 Number of data 50
0 <-25 -25/-20 -20/-15 -15/-10 -10/-5 -5/0 0/5 5/10 10/15 15/20 >25 % difference between cation and anion concentrations
400
Bulk open field 300 Throughfall Stemflow
200
Number of data Number of 100
0 -25 -20 -15 -10 -5 0 5 10 15 20 25 % difference between measured and calculated conductivity
Figure 3.3.1.1.1a: Departure from zeron of the percentage difference between Σ Cat and Σ An (PD) (above), and (below) of the percentage difference between measured and calculated conductivity (CD) for different types of deposition sample.
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3.3.1.1.2 Ion balance with DOC Figure 3.3.1.1.1a clearly illustrates the failure of the ion balance check in the case of THR and STF samples. This is also the case for soil water samples (not shown in figure) in which, in addition to high DOC concentrations, elevated concentrations of metals may also be present (see Chapter 3.3.1.1.3). The ion balance test can be used to evaluate the ionic contribution of DOC (all solutions are filtered through 0.45 um membrane filters before analysis) (Mosello et al., 2008). This study was carried out as part of the activities of the WG on QA/QC in laboratories regularly performing the chemical analysis of deposition and soil water samples within the framework of the ICP Forests and the EU/Forest Focus Programmes. About 6000 chemical analyses of bulk open field, throughfall and stemflow samples, which contained complete sets of all ion concentrations, alkalinity, conductivity and DOC, carried out in 8 different laboratories, were used to calculate empirical relationships between DOC and the difference between the sum of cations and the sum of anions. The aim was to determine the formal charge per mg of organic C. The samples covered a wide range of geographical and climatic conditions, as well as variables such as the proximity of the sea (chloride concentration) and the type of vegetation for THR and STF. Regression coefficients were obtained for the data sets from each laboratory, as well as for all the data combined, as follows:
Σ Cat – Σ An = δ1 DOC + δ0
-1 -1 -1 where the units are μeq L for the sum of ions and δ0, mg C L for DOC, and μeq (mg C) for δ1. The regressions were not significant for BOF, because of the relatively high error associated with the low DOC concentrations. In contrast, the regressions were statistically highly significant for THR and STF in all the 8 laboratories. In the next step, the charge contribution of DOC was determined as:
- [Org ] = β1*DOC + β0 where [Org-] (μeq L-1) is the ionic contribution of DOC. The value of PD was calculated again using the Σ An value including [Org-], and evaluated using the threshold values given in Table 3.3.1.1.1a.
An example of the regression coefficients, β1 and β0, as well as the appropriate statistical parameters, is given in Table 3.3.1.1.2a. The coefficients were further tested using an independent set of data from each laboratory. Comparison of the differences between the individual laboratories and the overall regression coefficients showed that the coefficients were generally applicable for deposition samples, and also suitable for estimating the contribution of organic acids in the ion balance test. This means a considerable improvement in the applicability of the ion balance as a validation criterion for samples with high DOC concentrations. The improvement in the ion balance check in an example data set is shown in Figure 3.3.1.1.2a. This evaluation can also be found in the annexed Excel file (http://www.icp- forests.org/DocsQualLab/AnalyticalDataValidation.xls; Chapter 5.1), which contains examples of analysis validation.
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Table 3.3.1.1.2a: Statistical parameters of the regression equations for determining the DOC contribution to the ion balance. THR = throughfall, STF = stemflow, N = number of samples, σ = standard deviation.
Units Broadleaves Conifers THR STF THR
N - 1454 597 1657 pH range U 4.0 - 7.9 3.8 - 8.1 4.1 – 7.0 pH mean± σ U 5.8±0.6 5.6±0.6 5.3±0.5 DOC range Mg C L-1 0-37 1-39 0-40 DOC mean± σ Mg C L-1 8±6 11±7 10±7
∑ Cat range µeq L-1 37-2736 30-5287 13-2601
∑ Cat mean± σ µeq L-1 418±321 593±539 316±278
∑ An range µeq L-1 29-2606 22-5303 10-2584 ∑ An mean± σ µeq L-1 377±304 545±523 279±265 ∑ Cat - ∑ An range µeq L-1 258 263 225 ∑ Cat - ∑ An mean± σ µeq L-1 41±59 48±58 37±41 Slope β1 µeq (mg C)-1 6.8±0,16 5.04±0.25 4.17±0.11 Intercept β0 µeq L-1 - -6.67±3.29 -5.01±1.32 12.32±1,63 P-value <0.0001 <0.0001 <0,0001 R2 0.56 0.4 0.47
100 Throughfall, no correction
80 Throughfall, DOC corrected
60
40 Number of data 20
0 -25 -20 -15 -10 -5 0 5 10 15 20 25 % difference between cation and anion concentrations
Figure 3.3.1.1.2a: Departure from zero of the percentage difference between Σ Cat and Σ An (PD, see text) without and with DOC correction.
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3.3.1.1.3 Ion balance with DOC and metals The ion balance for soil water samples is more complicated owing to the presence of metals (e.g. 3+ 2+ + 3+ 2+ + Al, Fe, Mn), their species (e.g. Al , Al(OH) ,Al(OH)2 , Fe , Fe(OH) , Fe(OH)2 ), their oxidation state (e.g. Fe3+/Fe2+; iron complexed with organic matter can occur in both oxidised and reduced forms and the reduced forms can exist under oxidising conditions when complexed with organic matter; see e.g. Clarke and Danielsson, 1995) and metal complexes with DOC (e.g. DOC-Fe, DOC- Al, DOC-Mn) in the solution. The calculation of bicarbonate from total alkalinity (see Chapter 3.3.1.1.1) is not completely correct because it is influenced by the different species of DOC in the solution. Therefore calculation of the formal charge per mg of organic C from the difference between the sum of cations and the sum of anions, as described in Chapter 3.3.1.1.2 for throughfall samples, also has to take into account the metals, their species and their complexes with DOC: Σ Cat + Σ Met (all inorg. species) + Σ Met (from DOC complexes) = Σ An + Σ Org- (from DOC complexes) where:
3+ 2+ + 3+ 2+ + 2+ + Σ Met = Al + Al(OH) +Al(OH)2 + Fe + Fe(OH) + Fe(OH)2 + Mn + Mn(OH) (and other inorg. species) Σ Met (from DOC complexes) = Al-DOC + Fe-DOC + Mn-Doc Σ Org- (from DOC complexes) = DOC-Fe + DOC-Al + DOC-Mn Normally only the total concentrations of the metals and the total concentration of DOC are measured in soil solution samples. Therefore calculation of the formal charge per mg of organic C using the following formula overestimates the formal charge of DOC when the highest possible charge for the metals (Al3+, Fe3+ ,Mn2+) is used and there is no correction for bicarbonate:
Σ cat + Σ mettotal – Σ an = δ1 DOC total In a study conducted by the WG on QA/QC in Laboratories, about 6200 chemical analyses on soil solution samples (complete sets of all ion and total metal concentrations, alkalinity, conductivity and DOC, carried out in the laboratories of 6 countries, were used to calculate empirical relationships between DOC and the difference between the sum of cations and metals and the sum of anions. The aim was to determine the formal charge per mg of organic C. The samples cover a wide range of geographical and climatic conditions. The results are shown in Figure 3.3.1.1.3a:
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Figure 3.3.1.1.3a: Calculation of the formal charge of DOC in 6140 soil solution samples from 5 countries (Germany, Finland, France, Norway and the United Kingdom)
When the calculated charge factor for DOC was included in the ion balances of these soil solution samples, 64 % of the samples had equal ion balances (within +/- 10 %) while only 30 % of the samples had equal ion balances without using the DOC correction. The results are different in the individual countries and at different pH values. Therefore the charge factor value obtained here can only be used as a first step in the procedure. It would be better to calculate the charge factor for specific countries or for similar types of plot. The chemical composition of DOC varies with depth down the soil profile (e.g. it is more polar at greater depth, Clarke et al., 2007), so the charge factor is also likely to vary with depth.
3.3.1.2 Conductivity check Conductivity is a measure of the ability of an aqueous solution to carry an electric current. This property depends on the type and concentration of the individual ions and on the temperature at which conductivity is measured. It is defined as: K = G * (L/A) where G = is the conductance (unit: ohm-1 or siemens; ohm-1 is sometime written as mho), defined as the reciprocal of resistance, A (cm2) is the electrode surface area, and L (cm) is the distance between the two electrodes. The units of K are ohm-1 cm-1. In the International System of Units (SI), conductivity is expressed as millisiemens per meter (mS m-1); this unit is also used by the IUPAC and accepted as the Nordic standard. The unit μS cm-1, where 1 mS m-1 = 10 μS cm-1 = 10 μmho cm-1, is also widely used in practice. The unit adopted in the ICP Forests programme is μS cm-1, and the reference temperature 25 °C. Conductivity depends on the type and concentration (activity) of the ions in solution; the capacity of a single ion to transport an electric current is given, in standard conditions and in ideal 2 -1 conditions of infinite dilution, by the equivalent ionic conductance ( i; unit: S cm equivalent ). Careful, precise conductivity measurement is an additional way of checking the results of chemical analyses. It is based on comparison between measured conductivity (CM) and the
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conductivity calculated (CE) from the individual ion concentrations (ci), multiplied by the respective equivalent ionic conductance ( i)
CE = i ci The ions used in the conductivity calculations are the same as those used in calculating the ion balance; the values of i for the different ions at temperatures of 20 and 25°C are given in Table -1 2 -1 3.1.1.1b. As the concentrations are expressed in μeq L , i is given as kS cm eq in order to obtain the conductivity in μS cm-1. The percentage difference, CD, is given by the ratio: CD = 100 * (CE-CM)/CM At low ionic strength (below 100 μeq L-1) in deposition samples, the discrepancy between measured and calculated conductivity should be no more than 2% (Miles & Yost 1982). At an ionic strength higher than 100 μeq L-1 (approximately at conductivity higher than 100 μS cm-1) it is necessary to use activity instead of concentration. This can be done by first calculating the ionic strength (Is, meq L-1) from the individual ion concentrations as follows:
2 Is = 0.5 ci zi / wi where:
-1 ci = concentration of the i-th ion in mg L ; zi = absolute value of the charge for the i-th ion; wi = gram molecular weight of the i-th ion. For an ionic strength higher than 100 μeq L-1, activities must be used instead of concentrations; in the range 100-500 μeq L-1 the Davies correction of the activity of each ion can be used, as proposed e.g. by Stumm and Morgan (1981) and A.P.H.A., A.W.W.A., W.E.F. (2005): ⎛ Is ⎞ −05..⎜ −03Is⎟ ⎝ 1+ Is ⎠ y = 10
Finally, the corrected conductivity is calculated as:
2 2 CEcorr=y CE= y i ci Immediate comparison of the measured and calculated conductivity makes it possible to identify single outlier values (see example in the annexed Excel file). Figure 3.3.1.1.1a shows the departure from zero of the CD values for different types of deposition sample. The pattern is different from that for the ion balance: the CD values do not show any great asymmetry for BOF, THR, or STF. The reason for this is that dissolved organic matter (DOM), which causes an imbalance between the cation and anion concentrations, does not contribute significantly to conductivity. In conclusion, a plot of measured and calculated conductivity is useful in the routine checking of a set of analyses. Departure of the results from linearity suggests the presence of analytical or some other kind of error.
3.3.1.3 Na/Cl ratio check In many parts of Europe sea salt is a major contributor of sodium and chloride ions in deposition and, as a result, the ratio between the two ions is similar to that of sea salt. This is true even in parts of Europe situated far from the sea, as has been shown from a statistical study conducted on more than 6000 samples covering the area from Scandinavia to South Europe (Mosello et al., 2005). In the validation file version 5/2010 21
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(Chapter 8.1 http://www.icp-forests.org/DocsQualLab/AnalyticalDataValidation.xls), samples with a ratio outside the range given below are marked as possible failures, and checks and/or re- analyses should be carried out. The ratio is calculated by expressing the concentrations on a molar (or equivalent) basis. 0.5 < (Na/Cl) < 1.5 If the Na/Cl ratio results systematically fall outside this range, this may be due to poor analytical quality in the measurement of low concentrations of sodium and chloride. In some localised areas, where there are other sources of Cl and/or Na (e.g. from anthropogenic activities), the Na/Cl ratio might be different from that of sea salt. Where this is suspected, it is recommended to carry out a study to confirm whether this is true or not.
3.3.1.4 N balance check The test is based on the fact that total dissolved nitrogen (DTN) concentration must be higher than the sum of nitrate (N-NO3), ammonium (N-NH4) and nitrite (N-NO2) concentrations. Although the measurement of nitrite is not mandatory in the ICP Forests programme, the following relationship must be verified, within the limits of analytical errors and whatever unit is used:
[N-NO3] + [N-NH4] < [DTN] If the relationship does not hold true, then the determination of one of the forms of nitrogen must be erroneous. However, if DON is very low, DTN may be approximately equal to NO3-N + NH4-N. In this case, normal (random) analytical errors may result in a slightly negative value of ([DTN] – ([NO3-N] + [NH4-N])), without there being any major problem with the analyses.
3.3.1.5 Comparison between measured conductivity and ion concentrations Samples with similar ionic ratios and different ionic concentrations should show linear correlation between conductivity and the sum of cations and anions. The linearity is valid if the H+ concentration is low (i.e. pH higher than 5.0). However, because of the high specific electric conductance of H+ (0.35 kS cm2 eq-1 at 25 °C, Table 3.3.1.1.1b), compared to that of the other ions (range 0.044-0.080 kS cm2 eq-1), small variations in H+ concentrations produce relatively strong variations in conductivity. In these cases, a conductivity value corrected for the contribution of hydrogen ion can be used:
+ -pH CH+ correct = CM - λ H+ [H ] = CM – 0.35 * 10 where the conductivities are expressed as μS cm-1 at 25°C and [H+] as μeq L-1 (Fig. 3.3.1.5a). Results diverging from linearity should be carefully checked in order to see whether there have been any mistakes in the analyses or in the data processing, or whether the values of some important ions are missing from the calculation.
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600
500 Bulk open field
400 Througfall ) -1 300
200 ions (µeq L ions (µeq Σ 100
0 0 5 10 15 20 25 30 -1 Xmeasured (µS cm at 25 °C)
600 Bulk open field 500 Througfall
) 400 -1
300 (µeq L + 200 ions - H
Σ 100
0 0 5 10 15 20 25 30 -1 Xmeasured - XH+ (µS cm at 25 °C)
Figure 3.3.1.5a: Examples of the relationships between conductivity and Σ Cat or Σ An, above without the correction for H+ contribution to conductivity, and below with the correction.
3.3.1.6 Phosphorus concentration as a contamination check If bird droppings contaminate the precipitation/throughfall/stemflow sample, this will 3- + + considerably alter the chemical composition of the sample. The concentrations of PO4 , K , NH4 version 5/2010 23
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and H+, for instance, will be affected. A phosphate concentration of 0.25 mg l-1 has been suggested as the threshold value for sample contamination by bird droppings (Erisman et al., 2003). Contamination by bird droppings is not always easily visible, so it may sometimes be detected only after the chemical analyses have been performed.
3.3.2 Checking organic and mineral soil samples results An important step in laboratory QA/QC is to check whether the result of an analysis is within the expected range and that the general relationships between soil variables are valid. Therefore two quality check procedures are recommended: plausible range checks and cross-checks.
3.3.2.1 Plausible range checks for organic and mineral soil samples For each variable, there is a 95 % probability that the analytical result will fall within the plausible min-max range given in Table 3.3.2.1a. Values outside this range may occur, but they need to be validated (e.g. checking of equipment and method, dilution factor, reported unit, sample characteristics, signs of contamination). Re-analysis may be necessary when no obvious deviations are found in order to ensure that the results are correct. Specific plausible ranges have been developed for organic material (forest floor, peat) and mineral soil samples. The number of significant decimal places for each variable is in accordance with the reporting format given in the ICP Forests Manual Part X (Soil Sampling and Analysis). Generally, the lower limit of the min-max range depends on the limit of quantification (LOQ) which is, in turn, determined by the instrument, method and dilution factor used. Instead of merely mentioning ‘LOQ’, we have listed the average LOQ values reported by the soil laboratories that participated in the 4th FSCC Ring test (Cools et al., 2006) as this was found to be more informative. Laboratories with lower LOQ values than the average will be able to quantify lower concentrations reliably. However, each laboratory should always report concentrations lower than its LOQ as “-1” and reporting the LOQ concentration to the required number of decimal places in the data quality report. The maximum value of the plausible range is determined by the maxima (mainly 97.5 percentile values) in the European forest soil condition database (first ICP Forests Level I Soil Survey). Information on the methods and data evaluation can be found in the Forest Soil Condition Report (EC, UN/ECE, 1997). As it encompasses all the European soil types, this range is relatively broad.
Table 3.3.2.1a: Plausible ranges for organic and mineral soil samples at the European level. The number of decimal places indicates the required precision for reporting. Organic sample Mineral soil sample Plausible range Plausible range Parameter Unit Min# Max Min# Max Moisture content (air-dry sample) %wt < 0.1 10.0 < 0.1 10.0 pH(H2O) - 2.0 8.0 2.5 10.0 pH(CaCl2) - 2.0 8.0 2.0 10.0 Organic carbon g/kg 120.0 580.0 < 1.2 200.0 Total N g/kg < 0.5 25.0 < 0.1 20.0 CaCO3 g/kg < 3 850 < 3 850 Particle size: clay %wt -- -- < 0.6 80.0 Particle size: silt %wt -- -- < 0.4 100.0 Particle size: sand %wt -- -- < 0.6 100.0 Aqua regia extractable P mg/kg < 32.8 3000.0 < 35.2 10000.0 Aqua regia extractable K mg/kg < 74.2 10000.0 < 81.4 40000.0 Aqua regia extractable Ca mg/kg < 45.9 100000.0 < 50.0 250000.0
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Organic sample Mineral soil sample Aqua regia extractable Mg mg/kg < 33.3 80000.0 < 38.5 200000.0 Aqua regia extractable S mg/kg < 128.6 7500.0 < 134.6 3000.0 Aqua regia extractable Na mg/kg < 20.6 3000.0 < 21.1 1000.0 Aqua regia extractable Al mg/kg < 76.1 40000.0 < 77.1 50000.0 Aqua regia extractable Fe mg/kg < 75.5 50000.0 < 82.6 250000.0 Aqua regia extractable Mn mg/kg < 7.2 35000.0 < 7.8 10000.0 Aqua regia extractable Cu mg/kg < 1.9 300.0 < 2.0 100.0 Aqua regia extractable Pb mg/kg < 2.4 1000.0 < 2.4 500.0 Aqua regia extractable Ni mg/kg < 1.5 300.0 < 1.6 150.0 Aqua regia extractable Cr mg/kg < 3.3 600.0 < 3.3 150.0 Aqua regia extractable Zn mg/kg < 2.0 1000.0 < 2.1 500.0 Aqua regia extractable Cd mg/kg < 0.5 18.0 < 0.5 6.0 Aqua regia extractable Hg mg/kg < 0.3 4.0 < 0.3 2.0 Exchangeable acidity cmol+/kg < 0.23 10.00 < 0.21 8.00 Exchangeable K cmol+/kg < 0.23 5.00 < 0.23 2.00 Exchangeable Ca cmol+/kg < 0.25 60.00 < 0.22 40.00 Exchangeable Mg cmol+/kg < 0.19 15.00 < 0.18 5.00 Exchangeable Na cmol+/kg < 0.18 1.50 < 0.17 1.00 Exchangeable Al cmol+/kg < 0.22 9.00 < 0.20 8.00 Exchangeable Fe cmol+/kg < 0.05 0.70 < 0.04 2.00 Exchangeable Mn cmol+/kg < 0.03 6.00 < 0.03 1.50 Free H+ cmol+/kg < 0.25 10.00 < 0.21 3.00 Total K mg/kg < 50.0 10000.0 < 50.0 50000.0 Total Ca mg/kg < 20.0 100000.0 < 20.0 500000.0 Total Mg mg/kg < 5.0 80000.0 < 5.0 250000.0 Total Na mg/kg < 20.0 5000.0 < 20.0 12000.0 Total Al mg/kg < 40.0 50000.0 < 40.0 100000.0 Total Fe mg/kg < 3.5 60000.0 < 3.5 250000.0 Total Mn mg/kg < 0.5 35000.0 < 0.5 15000.0 Reactive Al mg/kg < 44.6 5000.0 < 44.6 7500.0 Reactive Fe mg/kg < 48.4 5000.0 < 48.4 7500.0 # Values in bold are the average limit of quantification (LOQ) reported by the laboratories (Cools et al., 2006). The syntax is 'less than' LOQ (< LOQ).
For some parameters, national plausible ranges will be narrower due to the restricted set of soil and humus types and their local characteristics. It would be worthwhile developing regional plausible ranges specifically for soil samples originating from the region. When the analytical data from the soils part of the BioSoil Project become available for elaboration, it will be possible to further develop the plausible ranges on both a European and regional scale. If the values obtained in the analyses are outside the plausible range, the values should be marked with a flag for further investigation by the head of the laboratory and/or the responsible scientist. The head of the laboratory should be able to make comments in their report on possible reasons for the deviating value(s).
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3.3.2.2 Cross-checks between soil variables Because different parameters are determined on the same soil sample and many soil variables are auto-correlated, cross-checking is a valuable tool for detecting erroneous analytical results. Obviously, soils high with a high organic matter content should have high carbon and (organically bound) nitrogen concentrations. Calcareous soils should have elevated pH values, high exchangeable and total Ca concentrations, but low exchangeable acidity. Simple cross-checks have been developed for easy verification and detection of erroneous results.
3.3.2.2.1 pH check The soil reaction of organic and mineral soil material is measured potentiometrically in a suspension of a 1:5 soil:liquid (v/v) mixture of water (pHH2O) or 0.01 mol/l calcium chloride (pHCaCl2). The actual pH (pHH2O) and potential pH (pHCaCl2) are generally well correlated. Outliers may be detected using simple linear regression. Theoretically, without taking measurement uncertainty into account, the difference between both pH measurements should be less than 1 pH-unit. In practice, the difference between both pH measurements is generally less than 1.2 pH-unit, with pHCaCl2 always less or equal to pHH2O.
Check algorithm: 0 < [pHH2O - pHCaCl2] ≤ 1.2 Note that for peat soils, the difference between both pH measurements may be higher, up to 1.5 pH-units.
3.3.2.2.2 Carbon check According to the ICP Forests Manual Part X (Soil sampling and analysis), the recommended method for C determination is dry combustion using a total analyser (ISO 10694, 1995). In general, total organic carbon is obtained by subtracting inorganic carbon (TIC) from total carbon (TC), both of which are determined by the same analyser. Inorganic carbon can be estimated from the carbonate measurement (ISO 10693, 1994) using a calcimeter (Scheibler unit).
Check algorithm: [CCaCO3+TOC] ≤ TC with CCaCO3 = CaCO3 x 0.12 and
Check algorithm: CCaCO3 ≈ TIC The latter check cannot be performed if the carbonate concentration is below the LOQ (3 g kg-1 -1 carbonate or 0.36 g kg TIC).
3.3.2.2.3 pH-Carbonate check Routinely determining carbonate in soil samples with low pH values is a waste of time and resources. Carrying out a fast, cheap pH measurement can be used to decide whether carbonates are present and carbonate analysis is necessary. For an organic sample (> 200 g kg-1 TOC):
-1 Check algorithm: if pHCaCl2 < 6.0 then CaCO3 < 3 g kg (= below LOQ)
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For a mineral soil sample:
-1 Check algorithm: if pHH2O < 5 then CaCO3 < 3 g kg (= below LOQ)
-1 or: if pHCaCl2 < 5.5 then CaCO3 < 3 g kg (= below LOQ)
Conversely, if pHCaCl2 > 6, quantifiable amounts of carbonate are most likely present in the sample.
3.3.2.2.4 C/N ratio check Most of the nitrogen in a forest soil sample is organically bound. Carbon and nitrogen are linked through the C/N ratio of organic matter, which varies within a specific range. For an organic sample (> 200 g kg-1 TOC): Check algorithm: 5 < C/N ratio < 100 For a mineral soil sample: Check algorithm: 3 < C/N ratio < 75
3.3.2.2.5 C/P ratio check Similarly to C/N, the C/P ratio varies within expected ranges for organic and mineral soil samples. For an organic sample (> 200 g kg-1 TOC): Check algorithm: 100 < C/P ratio < 2500 Note that for peat soils, the C/P ratio may be greater than 2500. In the 5th FSCC soil ring test, the C/P ratio of the peat sample was ca. 4500. For a mineral soil sample: Check algorithm: 8 < C/P ratio < 750
3.3.2.2.6 C/S ratio check The C/S ratio varies within specific ranges for organic samples only. For an organic sample (> 200 g kg-1 TOC): Check algorithm: 20 < C/S ratio < 1000
3.3.2.2.7 Extracted/total element check In both organic and mineral soil samples the concentration of the aqua regia extractable elements K, Ca, Mg , Na, Al, Fe and Mn (pseudo-total extraction) should be less than their total concentrations after complete dissolution (total analysis). Therefore: Check algorithm: Extracted element ≤ Total element for the elements K, Ca, Mg ,Na, Al, Fe and Mn.
3.3.2.2.8 Reactive Fe and Al check Acid oxalate extractable Fe and Al indicate the active ( "amorphous") Fe and Al compounds in soils. Their concentration should be less than the total Fe and Al concentration. version 5/2010 27
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Check algorithm: Reactive Fe ≤ Total Fe Reactive Al ≤ Total Al For mineral soil samples, reactive Fe is usually less than 25 % of the total Fe, and reactive Al less than 10 % of the total Al.
3.3.2.2.9 Exchangeable element/total element check The elements bound to the cation exchange complex in the soil are also readily extracted using Aqua regia. Therefore, the concentration of exchangeable cations should always be lower than their Aqua regia extractable concentration.
-1 -1 A conversion factor is needed to convert from cmol(+) kg to mg kg .
Check algorithm: (Kexch x 391) ≤ Extracted K
Check algorithm: (Caexch x 200) ≤ Extracted Ca
Check algorithm: (Mgexchx 122) ≤ Extracted Mg
Check algorithm: (Naexch x 230) ≤ Extracted Na
Check algorithm: (Alexchx 89) ≤ Extracted Al
Check algorithm: (Feexchx 186) ≤ Extracted Fe
Check algorithm: (Mnexchx 274) ≤ Extracted Mn In general, the ratio between an exchangeable element and the same extracted element is higher in organic matrices than in mineral soil.
3.3.2.2.10 Free H+ and Exchangeable acidity check Two checks can be applied to Free H+ and Exchangeable acidity (EA). Check algorithm: Free H+ < EA
+ Check algorithm: EA ≈ Alexch+ Feexch+ Mnexch+ Free H For mineral soil samples, Free H+ is usually < 60 % of the Exchangeable acidity.
3.3.2.2.11 Particle size fraction sum check According to the ICP Forests Manual Part X (Soil sampling and analysis), laboratories have to report the proportion of sand, silt and clay fractions in mineral soil samples. However, different methods are used for determining each fraction. After shaking with a dispersing agent, sand (63 μm-2 mm) is separated from clay and silt with a 63 μm sieve (wet sieving). The clay (< 2 μm) and silt (2-63 μm) fractions are determined using the standard pipette method (sedimentation). When correctly applying the Soil manual procedure (SA03) (ICP Forests Manual Part X (Soil sampling and analysis), which is based on ISO 11277 (1998) and includes the correction for the dispersing agent, the sum of the three fractions should be 100 %. The mass of the three fractions should equal the weight of the fine earth (0- 2mm fraction), minus the weight of carbonate and organic matter which have been removed. Check algorithm: Σ [ clay (%), silt (%), sand (%) ] = 100 % Ensure that the clay, silt and sand fractions are reported in the right format as mistakes occur regularly, even in ring tests. 28 www.icp-forests.org/Manual.htm
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3.3.3 Check of analytical results for foliar and litterfall samples In comparison to the quality checks for the analytical results on soil, deposition and soil solution samples, devising robust procedures for checking foliage and litterfall analytical data is relatively difficult. In unpolluted areas, the concentration range of analytes in foliage is usually small compared with that in other matrices and so most of the results are plausible. Correlations between elements in foliage could be one possible tool for checking analytical results, but this is only suitable in cases where the sample plots are located very close to each other and have similar soil characteristics and the same tree species. As a result, this is probably not a useful procedure for checking the results in a European-wide survey.
3.3.3.1 Plausible range check for foliage In order to provide the laboratories carrying out foliage analyses with support on QA/QC issues, a preliminary list of plausible ranges for the element concentrations in foliage was agreed on at the 4th Expert Panel Meeting in Vienna 1997. However, these limits were very broad (see: http://bfw.ac.at/600/pdf/ Minutes_4.pdf). In order to improve the list and put it on a more sound statistical basis, the Forest Foliar Coordinating Centre removed 5% of the lowest and 5% of the highest results from the European Level I database. 90% of all the submitted Level I results fell within these limits. As the manual covers a large number of different tree species, it was necessary, in order to obtain sufficient data for meaningful statistical analysis, to group them into the main tree genera (Stefan et al., 1997). The new limits were adopted at the Expert Panel Foliage and Litterfall meeting in Madrid/Spain (2007). The Joint Research Centre was asked to carry out a statistical evaluation on the submitted Level II results in order to obtain statistical information about the concentration range for different tree species. The 5% and the 95% percentile limits for each tree species were calculated. 90% of the submitted results fell within these limits (see Table 3.3.3.1a). Results falling outside these limits should be checked and, if necessary, be re-analyzed. The report of the Level I foliage survey (Stefan et al., 1997) clearly shows that element concentrations in foliage vary considerably in different parts of Europe. There is a thus a need to calculate these limits for each country/laboratory using their own results. This would result in narrower limits that would provide a more reliable tool for detecting non-plausible results.
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Table 3.3.3.1a: Plausible range of element concentrations in the foliage of different tree species calculated from the Level II data sets (indicative values in grey).
Tree species n Limit N S P Ca Mg K C Zn Mn Fe Cu Pb Cd B g/kg g/kg g/kg g/kg g/kg g/kg g/kg μg/g μg/g μg/g μg/g μg/g ng/g μg/g Fagus 611 low 20.41 1.26 0.89 3.44 0.65 4.81 450 17.0 127 62 5.67 - 50 9.1 sylvatica high 29.22 2.12 1.86 14.77 2.50 11.14 550 54.2 2902 178 12.18 6.8 462 40.0 Quercus 37 low 12.86 0.91 0.63 4.81 0.98 1.19 450 13.0 509 83 6.89 - 63 15.9 cerris high 30.79 3.24 2.29 16.49 3.24 15.64 550 ------Quercus ilex 141 low 11.95 0.81 0.69 4.00 0.76 3.42 450 12.7 278 73 4.00 - - 21.7 high 17,24 1,41 1,22 10,32 2,62 8,46 550 41,0 5385 717 7,00 - - - Quercus 268 low 19.75 1.24 0.90 4.12 1.06 5.86 450 11.0 905 60 5.39 - 24 5.5 petraea high 29.84 2.01 1.85 10.46 2.26 11.16 550 25.0 4209 149 11.64 - - - Quercus pyrenaica 27 low 17.85 1.18 1.48 4.60 1.40 3.52 450 18.0 434 81 8.07 - - - (Q. toza) high 25,50 2,33 3,12 12,03 3,00 11,81 550 ------Quercus robur (Q. 313 low 20.31 1.36 0.97 3.33 1.09 5.80 450 14.0 219 64 5.50 0.1 40 23.4 pedunculata) high 30.69 2.21 2.55 12.26 2.85 12.64 550 50.0 2820 233 14.10 18.0 183 54.8 Quercus 39 low 11.39 0.85 0.47 4.29 1.22 4.37 450 17.0 291 62 6.11 - - 17.5 suber high 23.09 1.61 1.53 11.02 2.55 9.85 550 47.0 2887 621 20.00 - - - Abies alba 230 low 11.55 0.79 0.95 3.50 0.68 4.29 470 22.0 185 21 2.31 - 48 15.5 high 16.16 1.69 2.23 11.71 1.90 8.48 570 45.0 2510 85 5.89 - - - low 11.67 0.95 0.86 4.19 0.37 3.97 470 20.0 250 32 2.00 - 56 14.4 high 16.46 1.79 2.21 16.39 1.70 7.57 570 47.5 5241 121 6.45 - - - Picea abies 1763 low 10.39 0.70 1.01 1.83 0.66 3.65 470 16.0 165 22 1.41 - - 7.2 (P. excelsa) high 16.68 1.31 2.10 7.01 1.56 8.36 570 47.0 1739 91 5.94 2.9 226 29.4 low 9.47 0.69 0.81 2.26 0.44 3.41 470 12.0 198 27 0.94 - - 6.2 high 15.97 1.34 1.82 9.77 1.51 7.05 570 51.8 2376 118 7.07 5.2 169 32.9 Picea 108 low 12.67 0.98 1.04 1.21 0.78 5.56 470 8.4 147 31 0.70 - - 6.0 sitchensis high 17.61 1.75 2.56 8.02 1.41 10.89 570 33.8 1489 232 5.91 - - 42.0 low 11.87 0.92 0.84 1.41 0.50 4.62 470 9.5 160 33 0.70 - - 5.0 high 18.19 1.94 2.43 8.23 1.18 10.05 570 29.3 1734 133 4.67 - - 52.0 Pinus 40 low 11.31 0.75 0.98 1.02 0.79 3.56 470 ------contorta high 21.51 1.66 1.73 2.70 1.31 6.06 570 ------low 13.12 0.87 0.88 1.96 0.75 1.21 470 ------high 20.22 1.70 1.55 4.41 1.50 6.02 570 ------Pinus 30 low 9.22 0.92 0.80 2.12 1.84 3.20 470 23.0 32 230 - - - - halepensis high 14.28 1.68 1.79 8.04 2.89 8.67 570 ------Pinus nigra 81 low 8.42 0.51 0.81 0.97 0.56 3.88 470 18.8 60 29 1.81 0.6 399 8.9 high 21.18 1.44 1.57 4.42 2.08 8.30 570 67.7 1072 131 18.08 - - - low 7.97 0.44 0.75 1.17 0.35 3.89 470 19.0 109 69 1.80 0.9 380 8.7 high 23.49 1.93 1.71 6.90 2.06 7.34 570 70.0 1000 - - - - -
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Pinus 116 low 6.85 0.61 0.55 0.80 1.01 3.26 470 15.6 41 23 1.70 - - 15.0 pinaster high 13.71 1.29 1.24 3.80 2.47 7.14 570 39.0 825 579 5.03 - - - low 6.25 0.55 0.40 1.09 0.94 2.40 470 12.3 35 23 1.13 - - 20.0 high 13.27 1.44 1.38 6.02 2.88 6.86 570 36.8 794 111 4.68 - - - Pinus pinea 24 low 7.51 0.65 0.58 1.53 1.80 3.25 470 6.0 89 44 4.30 - - 28.5 high 11.30 1.65 1.20 4.40 3.00 6.70 570 ------Pinus 1859 low 11.40 0.75 1.11 1.61 0.64 3.77 470 32.0 172 18 2.28 - 50 9.2 sylvestris high 20.41 1.56 2.06 4.61 1.31 7.27 570 77.6 912 139 7,70 3.9 447 30.5 low 10.94 0.77 1.00 2.57 0.50 3.51 470 31.5 222 28 1.96 0.1 60 7.4 high 19.38 1.61 1.88 6.71 1.18 6.52 570 96.0 1332 171 6.88 5.6 507 33.9 Pseudotsuga 137 low 13.54 1.00 1.00 1.98 1.02 5.17 470 15.0 159 43 2.72 - 141 30.9 menziesii high 22.71 1.80 1.70 5.91 2.10 8.96 570 45.3 1661 129 5.95 - - - low 13.55 0.99 0.71 3.09 1.14 2.97 470 14.0 444 58 2.91 - - - high 29.23 2.18 1.45 9.64 2.73 7.30 570 - 155 279 - - - -
3.3.3.2 Plausible range check for litterfall Developing tolerable limits for litterfall is amore difficult task than that for foliage. Following collection, litterfall is sorted into different fractions – at a minimum two, foliar and non-foliar litter. Most countries sort the litterfall into three fractions – foliage, wood and fruit cones & seeds. Litterfall can then be analyzed either as a pooled sample or per fraction. The plausible range of the results of the chemical analysis of litter must be much bigger than for foliage. An important fraction in the litter is the foliar fraction, and for this fraction plausible ranges for selected tree species, based on the expert experience, are given in table 3.3.3.2a. Plausible ranges for the non-foliar fraction in litterfall will need to be determined.
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Table 3.3.3.2a: Plausible range of element concentrations in the foliar-litter of different tree species (indicative values in grey).
Tree Species (Foliar litter) Limit C S N P K Ca Mg Zn Mn Fe Cu B mg/g mg/g mg/g mg/g mg/g mg/g mg/g μg/g μg/g μg/g μg/g μg/g Betula pendula low 290 7.30 0.20 0.30 5.,00 1.00 105.00 600 45.0 6 high 330 21.00 1.20 1.40 12.50 2.00 170.00 3000 300.0 19 38 Castanea sativa low 390 9.00 0.20 0.20 4.50 1.40 35.00 700 5 high 420 13.00 0.70 0.55 10.50 2.00 45.00 2500 90.0 13 100 Fagus sylvatica low 460 1 9.00 0.50 2.00 4.00 0.80 25.00 650 70.0 4 2 high 510 2.2 19.00 1.90 8.00 17.00 2.00 35.00 1600 140.0 7 40 Fraxinus excelsior low 470 12.00 0.75 0.40 20.00 2.00 15.00 110 120.0 7 high 470 18.00 1.50 1.40 25.00 3.50 20.00 200 200.0 9 50 Quercus frainetto low 1.1 8.00 1.10 4.50 14.00 1.20 (Q. conferta) high 1.1 11.70 1.30 5.20 18.30 1.40 Quercus petraea low 460 8.00 0.30 2.00 7.00 1.30 14.00 700 50.0 5 high 510 12.00 0.60 4.00 10.00 2.00 25.00 1700 200.0 8 35 Quercus robur low 460 0.85 10.00 0.82 4.00 5.00 1.00 15.00 1000 90.0 6 7 (Q. pedunculata) high 510 1.7 19.00 2.00 8,00 13.00 2.00 25.00 1200 150.0 7 35 Abies cephalonica low 8.00 2.70 11.00 1.00 high 13.00 8.30 24.00 1.50 Picea abies low 1 6.50 0.60 1.00 2.50 0.70 (P. excelsa) high 520 1.5 12.60 1.20 4.20 16.00 2.20 Picea sitchensis low 440 1 6.00 0.60 1.50 4.00 0.60 15.00 250 40.0 2 high 530 1.1 13.00 1.10 3.00 11.00 1.00 35.00 1400 120.0 4 35 Pinus sylvestris low 490 0.62 5.00 0.40 1.00 2.00 0.50 20.00 180 35.0 2 high 530 0.62 10.00 0.80 3.00 11.00 0.80 45.00 800 150.0 5 45
3.3.4 Analyses in duplicate Performing duplicate analyses represents a very worthwhile quality check. The samples or digestion solutions/extracts are measured twice independently for the individual parameters, the results are compared, and their repeatability determined. As this is a very time-consuming and expensive procedure when the number of samples is large, it may be sufficient to analyse only part (e.g. 5%) of the samples in duplicate. If this is adopted, 5% of the samples should be randomly selected and analysed again at the end of the batch. Thus, one can check repeatability on the one hand and make sure that samples weren't mistakenly exchanged during the course of the analysis. If a mistake was determined, all samples in the batch will need to be re-analysed in duplicate.
3.3.5 Avoidance of contamination The contamination of samples can occur at any stage from the field to the final analysis result, including sampling in the in the field during, transportation to the laboratory, and the pre- treatment and analysis of the samples in the laboratory.
3.3.5.1 Water analyses As outlined deposition samples can become contaminated during the sampling period, e.g. as a result of bird droppings, and the laboratory should be informed about signs of such contamination (see Chapter 3.3.1.6). The transfer of deposition and soil water samples in the field from the sampling devices to the bottles used for transportation to the laboratory is another stage where contamination of the samples can occur. The best way to avoid this problem is to
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transport the collection devices (bottles, bags etc.) directly to the laboratory, if possible. The most important point during this step, as well as throughout the whole sample preparation procedure in the laboratory, is to avoid skin contact with the samples by using disposable gloves (non talc), and the use of clean equipment (e.g. glass- and plastic ware). Special care must be taken when filtering the samples, and at least separate plastic tubing (if used) and/or filtering devices for different types of sample (bulk, throughfall, stem flow, soil solution) should be used. Rinsing the filter capsule or funnel between the samples with the next sample, as well as with purified water, is highly recommended. If this is not possible, then an adequate amount of the next sample should be discarded after filtering before taking a sample for analysis. Control samples (ultra pure water) should be used after every 20 to 30 samples depending on the type of filtering system. It is always recommendable to start working with cleaner samples (e.g. bulk first with low analyte concentrations) and continue with the other types of sample in sequential order. Attention should also be paid to the different characteristics of the individual sample plots and their specific concentrations. It is important that filters used are appropriate to the analyses to be carried out, e.g. paper filters can affect ammonium and DOC determinations through contamination and the release of paper fibres that of course contain C. In some cases, the opposite may occur: sample loss through adsorption on filters. For the filtration of samples on which DOC is to be determined, glass fibre filters are recommended. The filters and the amount of ultra pure water needed to rinse off possible contaminants should be tested and checked by using blank charts. The filters should be handled with clean forceps. One highly recommendable procedure is to use a separate set of bottles for preparing the standard solutions for every single type of analysis. If the pH or conductivity value for a sample is exceptionally high, then it is recommendable to inform the persons carrying out the other analyses (which are usually performed later) about the “atypical” sample.
3.3.5.2 Organic and mineral soil analyses Samples of organic and mineral soil material need several preparatory steps prior to analysis. Contamination can occur in each of these steps. Cleanliness of equipment, glass- and plastic-ware, is a prerequisite for avoiding contamination and conforming with good laboratory practice. Milling and/or sieving is the first step in the pre-treatment of organic and mineral soil samples. The milling equipment is one possible source of contamination. Metals, especially, may be released through abrasion of the inner compartments or sieves. In the laboratory responsible for preparing the FSCC ring test samples, the use of a hammer-mill system with a titanium rotor and a stainless steel sieve was tested for milling organic samples. Milling resulted in elevated Ni and Cr concentrations of up to 3.6 and 2.2 mg kg-1, respectively, whereas for manual pulverization the increase was below 0.6 mg kg-1 for both metals. Although no systematic contamination was observed, the degree of contamination appeared to be a function of the hardness of the sample material (wood, bark) and the age of the sieve. The use of titanium rotors and sieves is therefore recommended, as well as periodical replacement of the sieves. According to the ICP Forests Manual Part X (Soil sampling and analysis), mineral soil samples should not be milled, but sieved with a 2 mm sieve. These sieves should be clean, with no traces of rust (i.e. oxidation on their metallic parts). Attention should be paid to ensure that no residues from tools (crusher, pestle, brush, cleaning equipment) end up in the samples as a result of thorough cleaning by brushing or wiping. This also holds true for other equipment (sample divider, mixer, splitter, riffler). When pre-treating silty or clayey soil samples, appropriate ventilation methods (i.e. air extraction equipment) should be used to avoid contamination of other samples or equipment via the air as well as for the health and safety of the laboratory technician. version 5/2010 33
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If a separate container is used to weigh and transfer sub-samples to extraction vessels, then it should be carefully brushed clean between samples to avoid cross-contamination. All glass- and plastic-ware should be cleaned by rinsing with a dilute acid solution or appropriate cleaning agent. Rinsing twice with distilled or de-ionized water and drying before re-use is a common practice. Ions adsorbed on the inner surfaces of extraction flasks or sample bottles coming into contact with extracts may be a source of contamination for subsequent analyses using the same containers. Finally, some types of filter paper used for filtration may contain contaminants. Many laboratories encounter problems with Na+ or other cations. Careful analysis of blanks and the filter material may indicate problematic elements that enhance the background noise.
3.3.5.3 Foliar and litterfall analyses There are many possible contamination sources in foliage and litterfall analyses. A short overview is given in Table 3.3.5.3a.
Table 3.3.5.3a: Possible contamination sources in foliage and litterfall analyses for some elements Element Possible contamination source
N NH3 from the laboratory air (only if the Kjeldahl method is used), reagents S Water (distilled or deionised), reagents P Dishwasher (detergent), water (distilled or deionised), reagents Ca Soil contamination from sampling, water (distilled or deionised), glassware, reagents Mg Soil contamination during sampling, water (distilled or deionised), glassware, reagents K Dishwasher (detergent), water (distilled or deionised), glassware, reagents Zn Soil contamination during sampling, Dishwasher (detergent), water (distilled or deionised), glassware, dust, reagents Mn Reagents Fe Soil contamination during sampling, water (distilled or deionised), glassware, dust, reagents Cu Water (distilled or deionised), glassware, reagents Pb Soil contamination during sampling, glassware, dust, reagents Cd Soil contamination during sampling, glassware, dust, reagents B Water (distilled or deionised), glassware, reagents Cr, Ni Instruments made of stainless steel used in sampling, pre-treatment etc. C Reagents
3.4 Inter-laboratory quality assurance In addition to the quality assurance carried out within each laboratory, there are also quality checks and procedures that can be used between different laboratories. These include ring tests, as well as the exchange of expertise and analytical methods employed between laboratories. In the case of international programmes, especially, the use of identical analytical methods and regular ring tests are of particular importance in ensuring comparability and joint evaluation of the data.
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3.4.1 Ring tests and ring test limits
3.4.1.1 Ring tests Within the ICP-Forests programme the participation in different ring tests is mandatory for all laboratories which are analysing samples from the ICP-Forests programme. In order to participate in the ring tests, each laboratory has to register on-line. Information about the registration procedure will be sent to both the NFCs and the responsible person for the ring tests in the laboratory. A series of inter-laboratory comparison tests is an excellent tool for improving the quality of the data produced by the participating laboratories over time. There are the twin benefits of improved expertise in using harmonised analytical methods as well as the use of the remaining ring test sample material as reference material for subsequent analyses. In instances where the analytical data generated in environmental monitoring or long-term ecological research programmes are of poor quality, then this may prevent the detection of trends, resulting in delays of up to three decades before they can be identified (Sulkava et al., 2007). To address this issue, tolerable limits for the deviation of the individual test result from the comparison mean value were selected for each variable measured. Results falling outside the tolerable limits indicate problems in the analytical procedure, or more general quality problems in the laboratory. The tolerable limits were set in order to act as a driving force to reduce measurement uncertainty and increase the comparability of results among the participating laboratories. As a result, the tolerable limits have, in some cases, been adjusted downwards in order to maintain their role as a driver for quality improvement as an increasing number of the laboratories meet this quality requirement. Ring tests should be carried out between the involved laboratories at regular intervals in order to ensure comparability of analytical data. This involves the dispatch of between 3 to 10 samples or solutions to the participating laboratories, where they are analysed using previously agreed analytical methods. The results are then returned to the organizers of the ring test. Prior to the dispatch of the ring test samples to the participating laboratories, the samples must be checked for homogeneity and, in the case of water samples, have been stabilized (i.e. by means of filtration through a 0.45 μm membrane filter and addition of appropriate acid where required). When mailed to the laboratories, the samples have to be packed in non-breakable flasks, and water samples should be kept cool during transportation. The analysis of 4 to 6 samples, representing different concentrations of the individual parameters, is the optimum, because only then can clear analytical trends be identified for each participating laboratory. This simplifies the detection of possible analytical mistakes and differences in the methods used. Particularly in the case of water samples, it is necessary to set a time period for completion of analysis and reporting of results. This avoids chemical/biological changes in the samples which, in turn, would lead to differences in the results. Care should be taken to agree on standard treatment of the samples and analytical methods. This includes their preparation such as sieving or grinding, digestion or extraction and determination of element concentrations. The effects of differing methods on the results of the ring test can only be investigated if the methods used are properly documented or a method-code used. The participating laboratories should carry out the ring tests as a part of their normal laboratory analysis runs so that the functioning of their normal routine activities can be checked. The organizers of the ring tests should ensure that forms and/or internet-based files are harmonised so that all the analysis data can be recorded in a standard fashion and similar version 5/2010 35
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evaluation programmes used. It is particularly important that for reporting purpose the units are defined including the required number of decimal places. There are a number of computer programmes on the market that comply with standards such as DIN 38402/42 (1984), and these can be used for evaluating the analysis data. Custom-made programmes can also be used. The deviation from the mean value and the coefficient of variation, as well as outliers, must be recorded for each parameter and for each sample.
3.4.1.2 Tolerable limits for ring tests In order to evaluate the results of ring tests and of the participating laboratories, tolerable deviations from the mean value, expressed as a percentage for each parameter and method, have to be determined. As a rule, the permitted deviations for double-stepped analytical methods (e.g. digestion/extraction and subsequent determination of the element concentration in the solution) are significantly larger than for direct element determination. All laboratories participating within ICP-Forests monitoring programme will get a qualification report after taking part in a ring test. In this report, information about the analysed and not analysed parameters and the passing of the qualification criteria for each parameter will be listed. The qualification criterion is that 50 % or more of the results of all ring test samples for a particular parameter must be within the appropriate tolerable limit. The WG on QC/QA in Laboratories and the various expert panels of the ICP Forests programme have proposed tolerable limits for all samples and parameters. They are described in detail in the following chapters. Laboratories without qualification for all parameters have the opportunity to requalify by reanalysis of the ring test samples and/or by receiving help through the assistance program for laboratories organized by the Working Group QA/QC in Laboratories. The laboratories have to report the new results to the organizers of the ring test together with the original reports of the analytical instruments and information about weight factors, dilution factors etc. and information about the reasons for the bad results during the ring test. The ring test organizers then will decide about the report from the laboratory. If the results are within the tolerable limits the laboratory will receive a requalification report. The results of the ring tests are integrated in the data reports to the EC and PCC and in the data base. This means that the bad ring test results will be known and can be used as a criterion for rejecting the data before being used in evaluations. When a lab did not qualify and did not make efforts to requalify, the ring test organisers will send a letter to the National Focal Centre and inform them about the consequence that their data possibly cannot be used for evaluations on an European level.
3.4.1.2.1 Tolerable limits for water ring tests Discussions on the results of the 1st and 2nd Deposition/Soil water ring tests highlighted the requirement for the determination of tolerable limits of acceptable variance amongst the participating laboratories. Thus, the deriving of tolerable limits (also known as data quality objectives (DQO)) are essential in ensuring the comparability of results from different laboratories. The tolerable limits need to be greater than the laboratory’s acceptable precision (if adhering to the QA/QC criteria) because they must also include a systematic error contribution. As is the case for determining the acceptance limits for single analyses validation checks (Chapter 3.3.1.1), selection of the tolerable limits should take into account the fact that excessively large acceptance thresholds are of little use for ensuring good data quality, while too strict threshold values that are frequently exceeded are ignored. The proposed set of values is only a preliminary step and it needs to be verified in practice and, if needed, changed. It also may be necessary to
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use different tolerable limits for “low“ or “high“ concentrations. However, a review of the results from further inter-laboratory exercises will show whether this is necessary or not. The proposed tolerable limits values for deposition/soil water inter-comparison at high and low concentrations are listed in Table 3.4.1.2.1, and are compared with the average of all the samples of the 95% confidence limit of the results obtained in the 2nd Ring Test (Marchetto et al., 2006), after the exclusion of outliers. It is evident that a significant proportion of the results still exceed the proposed tolerable limit values, indicating the need for improvement of performance in some laboratories. On the other hand, many laboratories had values lower than the tolerable limits, clearly indicating that it is possible to remain within these thresholds. The table also highlights a number of analyses where further work is required to improve analytical quality, such as alkalinity (low values in deposition samples), total nitrogen (at low concentrations) and DOC (both at low and high concentrations). The analytical problems associated with these determinations were discussed in detail in the work of Mosello et al., 2002, Marchetto et al., 2006 in relation to findings of the two ring test results.
Table 3.4.1.2.1: Comparing the results of the second ICP Forests/Forest Focus working ring test (Marchetto et al., 2006) with the proposed tolerable limits for deposition/soil water parameters. Parameter Conc. Conc. 2005 WRT Proposed Range Level 2 x SD Inter-Laboratory (% of mean except Tolerable limit (% of for pH) mean except for pH) pH Low >5.0 ± 0.27 u. pH ± 0.2 u. pH units pH High <5.0 ± 0.17 u. pH ± 0.1 u. pH Conductivity Low <10 - ± 20 -1 µS cm High >10 ± 13 ± 10 Calcium Low <0.25 ± 31 ± 20 mg L-1 High >0.25 ± 18 ± 15 Magnesium Low <0.25 ± 20 ± 25 mg L-1 High >0.25 ± 14 ± 15 Sodium Low <0.50 - ± 25 mg L-1 High >0.50 ± 12 ± 15 Potassium Low <0.50 ± 30 ± 25 mg L-1 High >0.5 ± 11 ± 15 Ammonium Low <0.25 ± 42 ± 25 mg N L-1 High >0.25 ± 16 ± 15 Sulphate Low <1.0 ± 11 ± 20 mg S L-1 High >1.0 ± 7 ± 10 Nitrate Low <0.5 ± 38 ± 25 mg N L-1 High >0.5 ± 10 ± 15 Chloride Low <1.5 ± 22 ± 25 mg L-1 High >1.5 ± 11 ± 15 Alkalinity Low <100 ± 161 ± 40 µeq L-1 High >100 ± 66 ± 25 Total dissolved Low <0.5 ± 51 ± 40 nitrogen High >0.50 ± 15 ± 20 mg L-1 Dissolved Low <1.0 ± 98 ± 30 organic carbon High >1.0 ± 20 ± 20 mg L-1 Other Low - - - (metals) High - - 20 mg L-1 version 5/2010 37
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3.4.1.2.2 Tolerable limits for soil ring tests For the inter-laboratory comparison of organic and mineral soil samples, tolerable limits were calculated on the basis of the Mandel’s h (a measure for the reproducibility) and Mandel’s k (a measure for the repeatability) statistics from earlier FSCC soil ring tests (De Vos, 2008). An explanation of the evaluation methodology for the soil ring tests based on ISO 5725-2 (1994) is given in the FSCC ring test reports (Cools et al., 2003, 2006, 2007). Tolerable limits for the soil ring tests are determined from the coefficient of variation for laboratory reproducibility (CVrepr). For many soil variables, CVrepr decreases with increasing concentrations, as shown for total nitrogen in Figure 3.4.1.2.2a., The reproducibility relative to the mean may be as high as 100 %, or even more at low concentrations, whereas there is less variation at higher concentrations. Therefore, tolerable CV’s are fixed for both low and high -1 concentrations for each soil variable. In the case of nitrogen, the CVrepr for low (≤ 1.5 g N kg DW) and high (> 1.5 g N kg-1 DW) concentration levels is set at 30% to 10% respectively (Fig. 3.4.1.2.2a). For some variables (e.g. pH), no distinction in tolerable limits between low and high concentrations is justified due to the linear relationship of the reproducibility curve.
Figure 3.4.1.2.2a: Power curves fitted to the results of total N in mineral soil samples of previous FSCC ring tests. The estimation of the CVs at low and high N concentrations are based on the turning point of the reproducibility curve. Therefore, in this example, the average CV for low and high concentrations of total N in mineral soils is 30 % and 10 % respectively.
Tolerable limits are set using a z-score of 1: the deviation from the mean is equal to the standard deviation (SD). Consequently, tolerable limits equal the average CVrepr in the earlier FSCC ring tests, rounded off to the nearest 5 %. Because the tolerable limits equal ±SD, in theory 68% of the labs should meet this criterion. However, a simulation for the 5th ring test revealed that, on the average, 70-90 % of the laboratories reported results within the tolerable range and 10-30 % failed, depending on the variable in question. In the future, as laboratory performance improves, these limits will be gradually narrowed using z- scores of less than 1.
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The tolerable limits for between laboratory variability for a range of soil parameters are given in Table 3.4.1.2.2.
Table 3.4.1.2.2: Inter-laboratory (i.e. between laboratories) tolerable limits for a range of soil parameters, including moisture content, soil texture, total, aqua regia extractable and exchangeable elements, reactive iron and aluminium and free acidity. Parameter Conc. Conc. Inter-laboratory Range Level Tolerable limit (% of mean) Moisture content Low ≤ 1.0 ± 25 (%) High > 1.0 ± 15
pHH2O - 2.0 – 8.0 ± 5 -
pHCaCl2 - 2.0 – 8.0 ± 5 - OC Low ≤ 25 ± 20 -1 g kg High > 25 ± 15 TN Low ≤ 1.5 ± 30 -1 g kg High > 1.5 ± 10 Carbonate Low ≤ 50 ± 130 -1 g kg High > 50 ± 40 Clay content Low ≤ 10.0 ± 50 % High > 10.0 ± 35 Silt content Low ≤ 20.0 ± 45 % High > 20.0 ± 30 Sand content Low ≤ 30.0 ± 45 % High > 30.0 ± 25 TotAl Low ≤ 20000 ± 35 -1 mg kg High > 20000 ± 10 TotCa Low ≤ 1500 ± 20 -1 mg kg High > 1500 ± 15 TotFe Low ≤ 7000 ± 20 -1 mg kg High > 7000 ± 10 TotK Low ≤ 7500 ± 15 -1 mg kg High > 7500 ± 10 TotMg Low ≤ 1000 ± 60 -1 mg kg High > 1000 ± 10 TotMn Low ≤ 200 ± 25 -1 mg kg High > 200 ± 10 TotNa Low ≤ 1500 ± 20 -1 mg kg High > 1500 ± 10 ExtrP Low ≤ 150 ± 45 -1 mg kg High > 150 ± 20 ExtrK Low ≤ 500 ± 60 -1 mg kg High > 500 ± 40 ExctCa Low ≤ 500 ± 70 -1 mg kg High > 500 ± 30 version 5/2010 39
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ExctMg Low ≤ 500 ± 60 -1 mg kg High > 500 ± 15 ExctrS - 35 - 1300 ± 35 mg kg-1 ExtrNa Low ≤ 75.0 ± 65 -1 mg kg High > 75.0 ± 50 ExtrAl Low ≤ 2500 ± 50 -1 mg kg High > 2500 ± 20 ExtrFe Low ≤ 2500 ± 40 -1 mg kg High > 2500 ± 15 ExtrMn Low ≤ 150 ± 30 -1 mg kg High > 150 ± 15 ExtrCu Low ≤ 5 ± 40 -1 mg kg High > 5 ± 15 ExtrPb - 3 - 70 ± 30 mg kg-1 ExtrNi Low ≤ 10 ± 40 -1 mg kg High > 10 ± 15 ExtrCr Low ≤ 10 ± 40 -1 mg kg High > 10 ± 25 ExtrZn Low ≤ 20 ± 40 -1 mg kg High > 20 ± 20 ExtrCd Low ≤ 0.25 ± 100 -1 mg kg High > 0.25 ± 55 ExctrHg - 0 - 0.16 ± 75 mg kg-1 Exch Acidity Low ≤ 1.00 ± 90 -1 cmol(+) kg High > 1.00 ± 35 ExchK Low ≤ 0.10 ± 45 -1 cmol(+) kg High > 0.10 ± 30 ExchCa Low ≤ 1.50 ± 65 -1 cmol(+) kg High > 1.50 ± 20 ExchMg Low ≤ 0.25 ± 50 -1 cmol(+) kg High > 0.25 ± 20 ExchNa -1 - 0.01-0.14 ± 80 cmol(+) kg ExchAl Low ≤ 0.50 ± 105 -1 cmol(+) kg High > 0.50 ± 30 ExchFe Low ≤ 0.02 ± 140 -1 cmol(+) kg High > 0.02 ± 50 ExchMn Low ≤ 0.03 ± 45 -1 cmol(+) kg High > 0.03 ± 25 Free H+ - 0.02-1.20 ± 100 -1 cmol(+) kg Reactive Al Low ≤ 750 ± 30 -1 mg kg High > 750 ± 15 Reactive Fe Low ≤ 1000 ± 30 -1 mg kg High > 1000 ± 15 40 www.icp-forests.org/Manual.htm
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3.4.1.2.3 Tolerable limits for plant (foliar and litterfall) ring tests The first step in the evaluation procedure of foliage ring tests is the elimination of outliers in the results of the Needle/Leaf interlaboratory comparison test (DIN 38402/42, 1984). This method identifies three types of outlier. The Grubbs test can be used to check the four replicates from each laboratory for outliers (outlier type 1). The next step is to compare the recalculated mean values of each laboratory with the mean value from all the laboratories, as well as with the Grubb test for outliers (outlier type 2). Finally, the recalculated standard deviation from the laboratories must be compared with the total standard deviation (F-test) in order to eliminate laboratories with an excessive standard deviation (outlier type 3). The outlier-free, total mean value and the outlier-free maximum and minimum mean value of all the laboratories can then be calculated. If the initially identified type 1 outliers lie between the calculated outlier-free maximum and minimum mean values then they are no longer considered as outliers, and they can be used in further evaluation of the inter-laboratory comparison test. The last step is to calculate the outlier- free statistical values (Fürst, 2004, 2005, 2006, 2007, 2008). In the next step an outlier-free mean value for each element/sample and the laboratory mean value and the recovery is calculated, and the results are compared with the tolerable limits given in Table 3.4.1.2.3. These tolerable limits for foliage samples were adopted by the Forest Foliar and Litterfall Expert Panel at the Meetings in Ås (1994), Vienna (1997), Bonn (1999), Prague (2003), Madrid (2007) and Hamburg 2009. As the concentration range in foliage and in litterfall is usually very small compared with that for soil and deposition matrices, it is not necessary to have different tolerable limits for high and low concentrations of all the elements. Tolerable limits for low concentrations of some elements are given in Table 3.4.1.2.3. Laboratory results within these limits will be accepted. However, laboratories with values exceeding these limits will need to take measures to improve their data quality.
Table 3.4.1.2.3: Inter-laboratory tolerable limits for high and low concentrations of mandatory and optional foliage and litterfall parameters. Parameter Conc. Conc. Inter-Laboratory Range Level Tolerable limit (% of mean) N Low ≤ 5.0 ± 15 -1 mg g High > 5.0 ± 10 S Low ≤ 0.50 ± 20 -1 mg g High > 0.50 ± 15 P Low ≤ 0.50 ± 15 -1 mg g High > 0.50 ± 10 Ca Low < 3.0 ± 15 -1 mg g High > 3.0 ± 10 Mg Low ≤ 0.50 ± 15 -1 mg g High > 0.50 ± 10 K Low ≤ 1.0 ±15 -1 mg g High > 1.0 ±10 Zn Low ≤ 20 ± 20 -1 µg g High > 20 ± 15 Mn Low ≤ 20 ± 20 -1 µg g High > 20 ± 15 Fe Low ≤ 20 ±30 -1 µg g High > 20 ±20 version 5/2010 41
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Parameter Conc. Conc. Inter-Laboratory Range Level Tolerable limit (% of mean) Cu Low - ±20 -1 µg g High Pb Low ≤ 0.50 ± 40 -1 µg g High > 0.50 ± 30 Cd Low - ± 30 -1 ng g High B Low ≤ 5.0 ± 30 -1 µg g High > 5.0 ± 20 C Low - ± 5 -1 g 100g High
3.4.2 Exchange of knowledge and expertise amongst laboratories The inter-laboratory comparisons conducted within the framework of ICP Forests are aimed at testing the proficiency of the laboratories, i.e. evaluating the comparability of the results and, if possible, identifying the main causes of errors. The laboratories must be involved in discussions on the outcome of the ring tests in order to assess and where necessary optimise their analytical quality. Laboratories with unacceptable results in ring tests will be invited to participate in an assistance programme organised by the WG on QA/QC in Laboratories. Close cooperation between these laboratories and laboratories with good laboratory practices is considered to be an effective way of improving laboratory proficiency. When determining the scope for assistance, it is necessary to take into account, not only the results of the ring test but the current state of the implementation of a quality programme in the laboratory, as well as the analytical methods used in the laboratory in question. Such information will be ascertained beforehand from a questionnaire that the laboratory will be obliged to complete. The assistance will consist of a few days’ visit to the laboratory, as well as a return visit, in order to identify and rectify easily detectable problems in the laboratory organisation and/or specific analytical processes. It is essential that the members of the staff actually involved in the analytical work participate in the assistance programme. The initial step of the assistance programme will entail drafting a list of analytical problems, with the emphasis on specific parameters analysed in the ICP Forests monitoring programme. Following from the inter-laboratory exchange visits, a short report will be produced detailing the laboratory’s activities, the analytical problems encountered and suggestions about how best they can be remedied. Through this assistance programme, the laboratory will be provided with sufficient information to enable them to make improvements in the quality of their analytical results.
3.4.2.1 Exchange of analytical expertise All laboratories are strongly invited to share their experience through internal info-sheets, developed as an easy tool for the exchange of information among laboratories about studies carried out in the laboratory which otherwise would not be published. The info-sheets are short Word files containing concise information about method comparison, development and implementation of new methods, material tests (e.g. on contamination or adsorption problems), sample pre-treatment, sample storage and technical information. Thus the work performed in one laboratory can help to avoid duplication in others.
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The circulation of information between the WG on QA/QC in Laboratories and the participating laboratories is ensured through the WG’s own website. This information, including details about past and ongoing ring tests, Excel files for QA/QC, downloadable scientific publications, analytical info-sheets, relevant contact addresses and useful links can be found at http://www.icp- forests.org/WGqual_lab.htm .
3.4.2.2 Exchange of samples The exchange of a limited number of routine samples between two laboratories is a simple and easy way to test the quality and comparability of the methods used. About 20 routine samples should be analysed in each laboratory and the results compared. This ensures that differences in the analytical methods used and problems encountered can be quickly and easily be identified, and steps taken to rectify the situation.
3.5 Quality indicators The development of the quality over time can be followed by using quality indicators. While, there are a number of quality indicators that can be used to evaluate the development of the participating laboratories QC/QA programme within ICP Forests, only 3 indicators were ultimately selected: Percentage of the results of a ring test within tolerable limits - Percentage of the results of a ring test with a precision <10% (not applicable to water ring tests) Mean percentage of parameters where laboratories use control charts The first two of them can be determined from results of the ring tests. The third one must be obtained from laboratories (for example an answer submitted with the ring test results or from the quality report forms)
3.5.1 Percentage of the results of a ring test within tolerable limits In each ring test, the number of results within the tolerable limits for all mandatory parameter will be related as a percentage to the total number of possible results. Where results are missing, they will be counted as outside the tolerable limit. It is expected that the percentage of results within the tolerable limits should increase as the laboratories analytical expertise improves over time.
3.5.2 Percentage of the results of a ring test with a precision <10% Normally, the precision (i.e. the repeatability of a result within a laboratory) should be <10 % for all parameters. In ring tests, with the exception of water samples, each sample typically has to be analysed 3 or 4 times. Therefore, where possible, the precision for each parameter can be calculated. The number of times the precision is <10 % can then be determined as a percentage of the total number of results where this calculation could be made. Ideally, the precision <10 % should be between 90 to 100 % for all parameters analysed and should become constant over time.
3.5.3 Mean percentage of parameters for which laboratories use control charts Control charts are a useful tool for checking the quality and the variation in quality over time (see Chapter 3.2). For each parameter and each matrix a laboratory has to use control charts. To foster the use of control charts for all parameters, it was decided to use as a quality indicator the percentage of parameters where laboratories use control charts. In future, all laboratories will have to include an annual quality report together with the data submission. In this report (see version 5/2010 43
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Chapter 3.6) each laboratory has to submit for each parameter in each matrix, the mean and the standard deviation of regularly measured reference materials (CRM or LRM). From this report, the percentage of parameters where control charts are used can be calculated for each laboratory. The mean percentage of all laboratories using control charts will be an indicator of improved laboratory quality control and should reach 100 % over the next number of years.
3.6 Quality reports In the ICP Forests monitoring programme, there is little information about the quality of the analytical data submitted each year, by attaching a quality report with the annual data submission, it is possible to link information on the analytical quality to the data in a database. To ensure this linkage, the quality report must have the same base information as the data submission report (e.g. plot No., country code, year, lab code). The quality information parameters which have to be reported are: country code year plot No. lab code LOQ for each parameter (if needed) detection method (coded like in ring test reports) for each parameter, ring test No % of results within tolerable limits for each parameter requalification information (yes/no) mean and standard deviation (%) for each parameter from control charts (if a laboratory use more than one control chart for a parameter it has to submit only data from one control chart in a normal concentration range). The quality report forms are part of the data submission forms (see ICP Forests Manual Part XVII Data submission forms).
4. References
Analytical Methods Committee. 1987. Recommendations for the definition, estimation and use of the detection limit. Analyst, 112: 199-204 A.P.H.A., AWWA & WEF. 2005. Standard methods for the examination of water and wastewater. 21th ed. American Public Health Association, Washington. Clarke, N., Danielsson, L.-G. 1995. The simultaneous speciation of aluminium and iron in a flow- injection system. Analytica Chimica Acta, 306: 5-20. Clarke, N., Wu, Y. and Strand, L.T. 2007. Dissolved organic carbon concentrations in four Norway spruce stands of different ages. Plant and Soil, 299: 275-285. Cools, N., Verschelde, P., Quataert, P., Mikkelsen, J. and De Vos, B. 2006. Quality Assurance and Quality control in Forest Soil Analysis: 4th FSCC Interlaboratory Comparison. INBO.R.2006.6.
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Forest Soil Coordinating Centre,Research Institute for Nature and Forest, Geraardsbergen, Belgium. 66 pages + annexes (on CD-Rom). Cools, N., Delanote, V., De Vos, B., Quataert, P., Roskams, P. and Scheldeman, X. 2003. Quality Assurance and Quality control in Forest Soil Analysis: 3rd FSCC Interlaboratory Comparison. Forest Soil Coordinating Centre, Institute for Forestry and Game Management, Geraardsbergen, Belgium. 301 p. Cools, N., Mikkelsen J.H., and De Vos, B. 2007. Quality Assurance and Quality control in Forest Soil Analysis: 5th FSCC Interlaboratory Comparison. INBO.R.2007.46. Forest Soil Coordinating Centre, Research Institute for Nature and Forest, Geraardsbergen, Belgium. 59 pages + annexes (on CD-Rom). Currie, L.A. 1999. Nomenclature in evaluation of analytical methods including detection and quantification capabilities (IUPAC recommendations 1995). Analytical Chimica Acta, 391: 105-126. Currie, L.A. 1999. Detection and quantification limits: origins and historical overview. Analytica Chimica Acta, 391, 127–134. De Vos, B., Lettens, S., Muys, B., Deckers, S. 2007. Walkley-Black analysis of forest soil organic carbon: recovery, limitations and uncertainty. Soil Use and Management 23 (3): 221-229. De Vos, B. 2008. Tolerable limits for interlaboratory forest soil ringtests. FSCC Supporting study of the EU Forest Focus Demonstration Project BioSoil. INBO.IR.2008.43. Research Institute for Nature and Forest, Brussels. DIN 38402. 1984. Deutsche Einheitsverfahren zur Wasser-, Abwasser- und Schlammuntersuchung – Allgemeine Angaben (Gruppe A) Ringversuche, Auswertung (A42). EC, UN/ECE and the Ministry of the Flemish Community, 1997, Vanmechelen, L., R. Groenemans and E. Van Ranst. Forest Soil Condition in Europe. Results of a Large-Scale Soil Survey. 1997 technical Report. EC, UN/ECE; Ministry of the Flemish Community; Brussels, Geneva, 259 pp. Erisman, J.W., Möls, H., Fonteijn, P., Geusebroek, M., Draaijers, G., Bleeker, A. and van der Veen, D. 2003. Field intercomparison of precipitation measurements performed within the framework of the Pan European Intensive Monitoring Program of ICP Forest. Environ. Pollut. 125: 139-155. Fürst, A. 2004. 6th Needle/Leaf Interlaboratory Comparison Test 2003/2004, Austrian Federal Office and Research Centre for Forests (ISBN 3-901347-46-1), Vienna/Austria. Fürst, A. 2005. 7th Needle/Leaf Interlaboratory Comparison Test 2004/2005, Austrian Federal Research and Training Centre for Forests, Natural Hazards and Landscape (ISBN 3-901347- 52-1), Vienna/Austria. Fürst, A. 2006. 8th Needle/Leaf Interlaboratory Comparison Test 2005/2006, Austrian Federal Research and Training Centre for Forests, Natural Hazards and Landscape (ISBN 3-901347- 60-7), Vienna/Austria. Fürst, A. 2007. 9th Needle/Leaf Interlaboratory Comparison Test 2006/2007, Austrian Federal Research and Training Centre for Forests, Natural Hazards and Landscape (ISBN 978-3- 901347-66-5), Vienna/Austria. Fürst, A. 2008. 10th Needle/Leaf Interlaboratory Comparison Test 2007/2008, Austrian Federal Research and Training Centre for Forests, Natural Hazards and Landscape (ISBN 978-3- 901347-73-3), Vienna/Austria. ISO 5725-2. 1994. Accuracy (trueness and precision) of measurement methods and results - Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method. International Organization for Standardization. Geneva, Switzerland. (available at www.iso.ch) version 5/2010 45
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ISO 8258. 1993. Shewhart control charts. International Organization for Standardization. Geneva, Switzerland. (available at www.iso.ch) ISO 10693. 1994. Soil Quality – Determination of carbonate content – Volumetric method. International Organization for Standardization. Geneva, Switzerland. 7 p. (available at www.iso.ch) ISO 10694. 1995. Soil Quality – Determination of organic and total carbon after dry combustion (elementary analysis). International Organization for Standardization. Geneva, Switzerland. 7 p. (available at www.iso.ch) ISO 11277. 1998. Soil Quality – Determination of particle size distribution in mineral soil material – Method by sieving and sedimentation. International Organization for Standardization. Geneva, Switzerland. 30 p. (available at www.iso.ch) ISO Guide 30, 1992. Terms and definitions used in connection with reference materials. International Organization for Standardization. Geneva, Switzerland. 8 p. (available at www.iso.org) IUPAC 1997. Compendium of chemical terminology, 2nd ed. Blackwell, Oxford. Marchetto, A., R. Mosello, G. Tartari, J. Derome, K. Derome, P. Sorsa, N. Koenig, N. Clarke, E. Ulrich, A. Kowalska. 2006. Atmospheric deposition and soil solution Working Ring Test 2005. E.U. Technical Report, Fontainebleau, France, 84 pp. Miles, L.J. & K.J. Yost. 1982. Quality analysis of USGS precipitation chemistry data for New York. Atmosph. Env., 16: 2889-2898. Mosello, R., J. Derome, K. Derome, E. Ulrich, T. Dahlin, A. Marchetto & G. Tartari. 2002. Atmospheric deposition and soil solution Working Ring Test 2002. E.U. Technical Report, Fontainebleau, France, 69 pp. Mosello, R., M. Amoriello, T. Amoriello, S. Arisci, A. Carcano, N. Clarke, J. Derome, N. Koenig, G. Tartari, E. Ulrich. 2005. Validation of chemical analyses of atmospheric deposition in forested European sites. J. Limnol., 64: 93-102. Mosello, R., T. Amoriello, S. Benham, N. Clarke, J. Derome, K. Derome, G. Genouw, N. Koenig, A. Orrù, G. Tartari, A. Thimonier, E. Ulrich, A-J Lindroos. 2008. Validation of chemical analyses of atmospheric deposition on forested sites in Europe: 2. DOC concentration as an estimator of the organic ion charge. J. Limnol 67: 1-15. Nordtest report TR 537. 2003. Handbook for Calculation of Measurement Uncertainty in Evironmental Laboratories. ISSN 0283-7234 (Approved 2003-05) Nordtest report TR 569. 2007. Internal Quality Control – Handbook for Chemical Laboratories. ISSN 0283-7234 / Edition 3 (Approved 2007-03) Stefan, K., Fürst, A., Hacker, R., Bartels, U. 1997. Forest Foliar Condition in Europe - Results of large- scale foliar chemistry surveys, ISBN 3-901347-05-4, EC-UN/ECE -FBVA 1997. Stumm, W. & J.J. Morgan. 1981. Aquatic chemistry. Wiley & Sons, New York: 780 pp. Sulkava, M., Luyssaert, S., Rautio, P., Janssens, I. A., Hollmén J. 2007. Modeling the effects of varying data quality on trend detection in environmental monitoring Elsevier Science Direct, Ecological Informations 2, 167-176. Thomsen, V., Schatzlein, D. & Mercuro, D. 2003. Limits of detection in spectroscopy. Spectroscopy, 18, 112–114. van Reeuwijk, L.P and Houba, V.J.G. 1998. Guidelines for Quality Management in Soil and Plant Laboratories. FAO Soils Bulletin – 74. FAO. Rome.
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5. Annexes
5.1 Excel worksheet for ion balance (with and without DOC correction), conductivity, N balance and Na/Cl ratio checks. The Excel worksheet permits different quality checks to be performed, as described in the text (Chapter 3.3.1). It can be downloaded from the ICP Forests website (http://www.icp- forests.org/DocsQualLab/AnalyticalDataVali dation.xls). It can be used as a tool for validating the results and as a file for data storage, according to the requirements of the operator and the procedure for data handling in the laboratory. The sheet contains green cells in which new data are to be entered using the units given at the top of the column. The units are the same as those in the ICP Forests database, and the correct use of units is essential for all further checking (ion balance, measured/calculated conductivity check etc.) of the results. Information about the type of sample (BOF, THR, STF) and the type of forest cover on the plot (BL = broadleaves, CON = conifers) is required for DOC correction of the ion balance calculation. They are used as strings for the calculations, and therefore they must be entered correctly. After entering the data in the green cells, the sheet calculates the ion balance (in accordance with the method described in Chapter 3.3.1.1.1) and the calculated conductivity, with and without correction for the ion strength (Chapter 3.3.1.2). The results of the tests are expressed in the worksheet as OK (test passed) or NO (test not passed) in the columns highlighted in yellow. The DOC contribution to ion balance is calculated using the empirical regressions described in Chapter 3.3.1.1.2. Selection of one the three alternative regression equations is based on the codes depicting the type of sample and the type of forest cover, as given in Table 3.3.1.1.2a. The principles and validation criteria for the Na/Cl ratio and N forms balance (i.e. N balance check) are described in Chapters 3.3.1.3 and 3.3.1.4. The graphs help in interpreting the results and identifying outliers. There are three graphs in the Excel worksheet: one for the ion balance, one for the comparison between measured and calculated conductivity, and one for the Na/Cl ratio. Other graphs can easily be added by the analysts themselves, e.g. for the comparison between measured conductivity and sum of anions or sum of cations and the conductivity corrected for the contribution of H+ and the sum of cations, with H+ excluded (Figure 3.3.1.5a). The Excel worksheet includes a sheet (notes) giving the meaning of the acronyms and a summary of the adopted validation criteria. The theoretical and statistical bases applied in developing the validation criteria for deposition data in the worksheet are based on thousands of full analysis sets provided by different laboratories, and are representative of different forest types and climatic conditions in Europe, ranging from northern Finland to southern Italy. The results of this work have been published in two papers (Mosello et al., 2005, 2008).
5.2 Excel worksheet for control charts The Excel worksheet that can be used for creating control charts (Chapter 3.2.1), can be downloaded from the ICP Forests website (www.icp-forests.org/WGqual_lab.htm): click on “Excel file with instruction and example of control chart use”. It also includes instructions on how to use the worksheet.
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5.3 List of commercially available reference materials
Reference material Matrix Type Comments Supplier BCR-408 water simulated rain water low European Commission, concentrations Directorate-General Joint Research Centre Institute for Reference Materials and Measurements Reference Materials Unit Retieseweg 111 B-2440 Geel Belgium E-Mail: jrc-irmm-rm- [email protected] Webpage: www.irmm.jrc.be Order by Fax: +32 (0)14 590 406 BCR-409 water simulated rain water high see above concentrations
BCR-100 plant beech leaves see above BCR-062 plant Olea europea (olive see above leaves ) BCR-129 plant powdered hay see above BCR-141R soil calcareous loam soil see above BCR-142R soil light sandy soil see above BCR-143R soil sewage sludge heavy metal see above amended soil pollution
BCR-146R soil/organic sewage sludge of heavy metal see above material industrial origin pollution
BCR-320 soil river sediment see above FSCC RM1 soil loamy forest soil moderate ICP - Forest Soil Coordinating concentrations Centre Gaverstraat 4 9550 Geraardsbergen Belgium 1575a plant pine needles Standard Reference Materials Program, National Institute of Standards and Technology 100 Bureau Drive, Stop 2322 Gaithersburg, MD 20899-2322 USA E-Mail: [email protected] Webpage: www.nist.gov/srm Order by Fax: (301) 948-3730 1515 plant apple Leaves see above 1547 plant peach Leaves see above 1570a plant spinach leaves see above 1573a plant tomato leaves see above Sample 2 from the 8th plant spruce needles Federal Research and Training needle/leaf inter- Centre for Forests, Natural laboratory test Hazards and Landscape (ICP Forests) M. Alfred Fürst Seckendorff-Gudent Weg 8 A-1131 Vienna Austria E-Mail: [email protected] Web: www.ffcc.at Order per fax: +43-1-87838- 1250 Sample 4 from the 6th plant maple leaves see above needle/leaf inter- laboratory test (ICP Forests)
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5.4 Definitions and terminology accuracy – the closeness of agreement between a test result and the accepted reference value. NOTE: The term accuracy, when applied to a set of test results, involves a combination of random components and a common systematic error or bias component. (ISO 3534-1:1993) bias – a systematic difference or systematic error between an observed value and some measure of the truth. Generally used to describe the inaccuracy of a method relative to a comparative method in a method comparison experiment. (Westgard J.O., 2003) blank – is defined as the sample without the analyte. blank determination - an analysis of the sample without the analyte or attribute, or an analysis without the sample e.g. going through all steps of the procedure with the reagents only. (van Reeuwijk and Houba, 1998) blank chart – a type of control chart used to detect the possibility of occasional contamination with the use of blank. blind sample - in chemical analysis: a selected sample whose composition is unknown except to the person submitting it; used to test the validity of the measurement process. or: a sample with known content of the analyte. The analyst is aware of the possible presence of the blind sample but he does not recognize the material as such. (van Reeuwijk and Houba, 1998) calibration – operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties and, in a second step, uses this information to establish a relation for obtaining a measurement result from an indication. (VIM:2008) or: Process of determining the relation between the output or response of a measuring instrument and the value of the input. Calibration typically involves the use of a measuring standard. certified reference material (CRM) - a reference material, accompanied by a certificate, one or more of whose property values are certified by a procedure which establishes traceability to an accurate realization of the unit in which the property values are expressed, and for which certified value is accompanied by an uncertainty at a stated level of confidence. (ISO Guide 30:1992) or: reference material, accompanied by documentation issued by an authoritative body and providing one or more specified property values with associated uncertainties and traceabilities, using valid procedures. (VIM:2008) control chart - a graphical method for evaluating whether a testing process is operating within the limits expected from its inherent random variation. (Westgard J.O., 2003) control levels/limits – the limits on a control chart such that, when data points fall outside them, special causes of variation must be suspected. These are normally three standard deviations either side of the mean. Note: control limits are calculated, not assigned. They are a statistical point. There are different formulae for calculating control limits, depending on the different type of control charts being used.
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control sample – (sequence – control sample) a sample with an extreme content of the analyte but falling within the working range of the method. It is inserted at random in a batch to verify the correct order of the samples. (van Reeuwijk and Houba, 1998) conventional true value – value attributed to a particular quantity and accepted, sometimes by convention, as having an uncertainty appropriate for a given purpose. (http://www.measurementuncertainty.org – VIM:1993) or: quantity value attributed by agreement to a quantity for a given purpose. (VIM:2008) error – measured quantity value minus a reference quantity value(VIM:2008) or: the collective noun for a departure of the result from the true value. (van Reeuwijk and Houba, 1998) homogeneity - the degree to which items (e.g. tested substance) are similar. instrument limit of detection (IDL) – the concentration equivalent to a signal, due to the analyte of interest, which is the smallest signal that can be distinguished from background noise by a particular instrument. The IDL should always be below the method detection limit, it is not used for compliance data reporting, but may be used for statistical data analysis and comparing the attributes of different instruments. (Standard Methods, 18th Edition) interference - artificial increase or decrease in apparent concentration or intensity of an analyte due to the presence of a substance that reacts nonspecifically with either the detecting reagent or the signal itself. (Westgard J.O., 2003) interlaboratory comparison - organization, performance and evaluation of tests on the same or similar test items by two or more laboratories in accordance with predetermined conditions. (ISO/IEC Guide 43-1:1997) limit of detection (LOD) - the smallest measure, that can be detected with reasonable certainty for a given analytical procedure. (IUPAC:1997) or: measured quantity value, obtained by a given measurement procedure, for which the probability of falsely claiming the absence of a component in a material is β, given a probability α of falsely claiming its presence. (VIM:2008) or: the smallest test value that can distinguished from zero. (Westgard J.O., 2003) or: the lowest amount of analyte in a sample which can be detected but not quantitated as an exact value. (Westgard J.O., 2003) limit of quantification (LOQ) – the lowest concentration of an analyte that can be determined with acceptable precision (repeatability) and accuracy under the stated conditions of the test.’ (NATA Tech Note #13) or: performance characteristic that marks the ability of a CMP to adequately “quantify” an analyte (…) The ability to quantify is generally expressed in terms of the signal or analyte (true) value that will produce estimates having a specified relative standard deviation (RSD), commonly 10%. (IUPAC:1997)
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local reference material (LRM) – a material prepared and standardized in a laboratory, used especially for daily control of analytical process. or: a local reference sample (in-house) for which one or more property values have been established by the user laboratory, possibly in collaboration with other laboratories. The sample should be sufficiently stable and homogeneous for the properties concerned (van Reeuwijk and Houba, 1998) matrix - the components of material system, except the analyte. Used to refer to the physical and chemical nature of the speciment, the substances present, and their concentrations. (Westgard J.O., 2003) mean chart (X-chart) – a control chart used to check the repeatability of the measurements. In this chart the sample means are plotted in order to control the mean value of a variable. measurement uncertainty – non-negative parameter characterizing the dispersion of the quantity values being attributed to a measurand, based on the information used. (VIM:2008) (method) validation – verification, where the specified requirements are adequate for an intended use. (VIM:2008) nominal value - rounded or approximate value of a characterizing quantity of a measuring instrument or measuring system that provides guidance for its appropriate use. (VIM:2008) outlier - an observation that is numerically distant from the rest of the data. or: an observation that lies outside the overall pattern of a distribution. (Moore and McCabe 1999) or: discrepant value. Value which do not agree with the pattern of the majority of other values. (Westgard J.O., 2003) precision – the closeness of agreement between independent test results obtained under prescribed conditions. (ISO 3534-1:1993) proficiency testing – determination of laboratory testing performance by means of interlaboratory comparisons. (ISO/IEC Guide 2) quantity - property of a phenomenon, body, or substance, where the property has a magnitude that can be expressed as a number and a reference. (VIM:2008) random errors - a component of measurement error that in replicate measurements varies in an unpredictable manner. (VIM:2008) or: an error that can be positive or negative, the direction and exact magnitude of which cannot be exactly predicted. (Westgard J.O., 2003) range chart (R-chart) – a type of control chart used to check the repeatability of the analysis, usually of duplicate determinations. In this chart, the sample ranges are plotted in order to control the variability of a variable. reference material (RM) – a material or substance one or more of whose property values are sufficiently homogeneous and well established to be used for the calibration of an apparatus, the assessment of a measurement method, or for assigning values to materials. (ISO Guide 30:1992) or: version 5/2010 51
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a secondary reference material or substance , one or more of whose property values are accurately determined by number of laboratories with a stated method), and which values are accompanied by an uncertainty at a stated level of confidence. The origin of the material and the data should be traceable (van Reeuwijk and Houba, 1998) or: a material, sufficiently homogeneous and stable with reference to specified properties, which has been established to be fit for its intended use in measurement or in examination of nominal properties. (VIM:2008) repeatability - precision under repeatability conditions. (ISO 3534-1:1993) repeatability conditions – conditions where independent test results are obtained with the same method on identical test material in the same laboratory by the same operator using the same equipment within short intervals of time. (ISO 3534-1:1993) or: condition of measurement, out of a set of conditions that includes the same measurement procedure, same operators, same measuring system, same operating conditions and same location, and replicate measurements on the same or similar objects over a short period of time. (VIM:2008) replicate result - the result of replicated measurement. (van Reeuwijk and Houba, 1998) reproducibility – precision under reproducibility conditions. (ISO 3534-1:1993) reproducibility conditions – conditions where test results are obtained with the same method on identical material in different laboratories by different operators using different equipment. (ISO 3534-1:1993) or: condition of measurement, out of a set of conditions that includes different locations, operators, measuring systems, and replicate measurements on the same or similar objects. (VIM:2008) stability - in the technical sense in chemistry means thermodynamic stability of a chemical system. Chemical systems might include changes in the phase of matter or a set of chemical reactions. standard deviation (s) – a statistic that descibes the dispersion or spread of a set of measurements about the mean value of a Gaussian or normal distribution. (Westgard J.O., 2003) systematic error – a component of measurement error that in replicate measurements remains constant or varies in a predictable manner. (VIM:2008) or: an error that is always in one direction and is predictable. (Westgard J.O., 2003) target value – used in proficiency testing to designate the correct value usually estimated by the mean of all participant responses, after removal of outliers, or by the mean established by definitive or reference method. (Westgard J.O., 2003) test sample - the sample, prepared from the laboratory sample, from which test portions are removed for testing or for analysis. (IUPAC:1997) traceability- a property of the result of a measurement or the value of a standard whereby it can be related to stated references, usually national or international standards through an unbroken chain of comparison all having stated uncertainties. (Westgard J.O., 2003) trueness - the closeness of agreement between the average value obtained from a large series of test results and an accepted reference value.
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NOTE: The measure of trueness is usually expressed in terms of bias. (ISO 3534-1:1993) true value - value consistent with the definition of a given particular quantity. Notes: 1) This is a value that would be obtained by a perfect measurement. 2) True values are by nature indeterminate. or: quantity value consistent with the definition of a quantity. (VIM:2008) t-value – a statistical value which depends on the number of data and the required confidence. (van Reeuwijk and Houba, 1998) warning levels/limits – the limits on a control chart, normally set at two standard deviations either side of the mean. working range - set of values of measurands for which the error of a measuring instrument is intended to lie within specified limits z-score – statistically: a dimensionless quantity derived by subtracting the population mean from an individual test result and then dividing the difference by the population standard deviation. Often used for individual rating of the proficiency of a laboratory in interlaboratory comparisons. Following this formulation, the z-score is a function of both the accuracy of the individual test result and the dispersion of the whole set of results, and it can not be used to compare the results of different tests.
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