Soil Survey Laboratory Information Manual Soil Survey Investigations Report No. 45 Version 2.0 February 2011 Compiled and Edited by Rebecca Burt United States Department of Agriculture Natural Resources Conservation Service National Soil Survey Center Lincoln, Nebraska Cover Photos: The soil survey landscape (upper left) and pedon (upper right) are from Lyon County, Nevada. The landscape is a typical area of Cleaver soils, and the pedon is representative of the Cleaver series. Cleaver soils are classified as loamy, mixed, superactive, mesic, shallow Typic Argidurids. These well drained soils are shallow to an indurated duripan. They formed in alluvium derived from igneous rocks and are on fan remnants in the Great Basin section of the Basin and Range physiographic province. The present vegetation in the rangeland ecological site is mainly Bailey’s greasewood (Sarcobatus baileyi), shadscale (Atriplex confertifolia), winterfat (Krascheninnikovia lanata), Nevada jointfir (Ephedra nevadensis), and cheatgrass (Bromus tectorum). (Photos courtesy of Joseph V. Chiaretti, NRCS, National Soil Survey Center, Lincoln, Nebraska.) Lower left: The National Soil Survey Laboratory in Lincoln, Nebraska. Lower right: A thin section. Soil Survey Laboratory Information Manual Soil Survey Investigations Report No. 45 Version 2.0 February 2011 Compiled and Edited by Rebecca Burt United States Department of Agriculture Natural Resources Conservation Service National Soil Survey Center Lincoln, Nebraska i Trade names are used in this manual solely for the purpose of providing specific information. Mention of a trade name does not constitute a guarantee of the product by the USDA nor does it imply an endorsement by the USDA. ______________________________________________________________________ USDA Nondiscrimination Statement The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410, or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. Citation: Soil Survey Staff. 2011. Soil Survey Laboratory Information Manual. Soil Survey Investigations Report No. 45, Version 2.0. R. Burt (ed.). U.S. Department of Agriculture, Natural Resources Conservation Service. ii Contents Method Page code Preface xix I. Introduction 1 II. Primary Characterization Data 11 1 Sample Collection and Preparation 1 12 1.1 Field Sample Collection and Preparation 1A 13 1.1.1 Site Selection 1A1 13 1.1.1.1 Geomorphology 1A1a 13 1.1.1.2–4 Pedon, Water, and Biological Sampling 1A1b-d 13 1.1.2 Classification Systems and Soil Survey 13 1.2 Laboratory Sample Collection and Preparation 1B 23 1.2.1 Soil Samples 1B1 23 1.2.2 Water Samples 1B2 26 1.2.3 Biological Materials 1B3 26 2 Conventions 2 27 2.1 Methods and Codes 2A 27 2.2 Data Types 2B 28 2.3 Particle-Size Size-Fraction Basis for Reporting Data 2C 29 2.3.1 Particles <2 mm 2C1 29 2.3.2 Particles <Specified Size >2 mm 2C2 29 2.4 Sample Weight Basis for Reporting Data 2D 29 2.4.1 Air-Dry/Oven-Dry 2D1 29 2.4.2 Field-Moist/Oven-Dry 2D2 29 2.4.3 Correction for Crystal Water 2D3 29 2.5 Significant Figures and Rounding 2E 30 2.6 Data Sheet Symbols 2F 30 3 Soil Physical and Fabric-Related Analyses 3 30 3.1 Particle-Size Distribution Analysis 3A 31 3.1.1 Classification Systems 31 3.1.2 Particles <2 mm 3A1 33 3.1.2.1 Pipet Analysis 3A1a 38 3.1.2.1.1 Total Clay, <0.002-mm (<2 µm) 39 3.1.2.1.2 Total Silt, 0.002 to 0.05 mm 42 3.1.2.1.3 Total Sand, 0.05 to 2.0 mm 42 3.1.2.1.4 Fine Clay, <0.0002 mm (<0.2 µm) 43 3.1.2.1.5 Carbonate Clay, <0.002 mm (<2 µm) 44 3.1.2.1.6 Fine Silt, 0.002 to 0.02 mm 45 3.1.2.1.7 Coarse Silt, 0.02 to 0.05 mm 45 iii Method Page code 3.1.2.1.8 Very Fine Sand, 0.05 to 0.10 mm 45 3.1.2.1.9 Fine Sand, 0.10 to 0.25 mm 46 3.1.2.1.10 Medium Sand, 0.25 to 0.50 mm 46 3.1.2.1.11 Coarse Sand, 0.5 to 1.0 mm 46 3.1.2.1.12 Very Coarse Sand, 1.0 to 2.0 mm 46 3.1.2.2 Hydrometer Analysis 46 3.1.2.3 Water Dispersible 3A1a6 47 3.1.2.3.1 Total Clay, <0.002 mm (<2 µm) 48 3.1.2.3.2 Total Silt, 0.002 to 0.05 mm 49 3.1.2.3.3 Total Sand, 0.05 to 2.0 mm 49 3.1.2.4 Soil Loss Through Water and Wind Erosion, 50 Processes, Case Studies, and Major Developments 3.1.3 Particles >2 mm 3A2 55 3.1.3.1 Weight Estimates 3A2a 56 3.1.3.1.1 By Field and Laboratory Weighing 3A2a1 56 3.1.3.1.2 From Volume and Weight Estimates 3A2a2 56 3.1.3.2 Volume Estimates 3A2b 56 3.2 Bulk Density 3B 57 3.2.1 Assessments and Predictions 57 3.2.2 Soil Compaction, Process and Case Studies 59 3.2.3 Saran-Coated Clods 3B1 61 3.2.3.1 Field-State (Bf) 3B1a 61 3.2.3.2 33-kPa Equilibration(B33) 3B1b 61 3.2.3.3 Oven-Dry (Bod) 3B1c 61 3.2.3.4 Rewet (Br) 3B1d 61 3.2.4 Reconstituted 3B2 61 3.2.4.1 33-kPa Equilibration 3B2a 61 3.2.4.2 Oven-Dry 3B2b 61 3.2.5 Compliant Cavity 3B3 61 3.2.6 Ring Excavation 3B4 61 3.2.7 Frame Excavation 3B5 61 3.2.7.1 Field-State 3B5a 61 3.2.8 Soil Cores 3B6 61 3.2.8.1 Field-State 3B6a 61 3.3 Water Retention 3C 66 3.3.1 Definitions and Data Assessments 66 3.3.2 Pressure-Plate Extraction 3C1 77 3.3.2.1–5 6, 10, 33, 100, or 200 kPa 3C1a-e 77 3.3.2.1–5.1.1 <2-mm (Sieved), Air-Dry 3C1a-e1a 77 3.3.2.1–4.2 Natural Clods 3C1a-d2 77 iv Method Page code 3.3.2.1–4.3 Soil Cores 3C1a-d3 77 3.3.2.1.3.4 Rewet 3C1c4 77 3.3.2.1.3.5 Reconstituted 3C1c5 77 3.3.3 Pressure-Membrane Extraction 3C2 78 3.3.3.1 1500 kPa 3C2a 78 3.3.3.1.1 <2-mm (Sieved) 3C2a1a 78 3.3.3.1.1.1–2 Air-Dry or Field-Moist 3C2a1b 78 3.3.4 Field-State 3C3 79 3.3.4.1 Cores 79 3.3.4.2 Clods 79 3.3.4.3 Bulk 79 3.4 Ratios, Estimates, and Calculations Related to 3D 80 Particle-Size Analysis, Bulk Density, and Water Retention 3.4.1 Air-Dry/Oven-Dry Ratio (AD/OD) 3D1 80 3.4.2 Field-Moist/Oven-Dry Ratio (FM/OD) 3D2 80 3.4.3 Correction for Crystal Water 3D3 80 3.4.4 Coefficient of Linear Extensibility (COLE) 3D4 81 3.4.5 Water Retention Difference (WRD), Whole Soil 3D5 82 3.4.6 1500-kPa Water Content/Total Clay 3D6 84 3.4.7 Total Silt Fraction 3D7 86 3.4.8 Total Sand Fraction 3D8 87 3.4.9 2- to 5-mm Fraction 3D9 87 3.4.10 5- to 20-mm Fraction 3D10 87 3.4.11 20- to 75-mm Fraction 3D11 87 3.4.12 0.1- to 75-mm Fraction 3D12 88 3.4.13 >2-mm Fraction 3D13 88 3.5 Micromorphology 3E 88 3.5.1 Thin Sections 3E1 88 3.5.1.1 Preparation 3E1a 88 3.5.1.2 Interpretations 3E1b 89 3.6 Aggregate Stability 3F 109 3.6.1 Structure and Aggregates 109 3.6.2 Sealing, Crusting, and Disaggregation, Processes 110 and Case Studies 3.6.3 Wet Aggregate Stability, Wet Sieving 3F1 114 3.7 Particle Density 3G 114 3.7.1 Estimates for Various Minerals and Parent Materials 115 3.7.2 Pycnometer, Gas Displacement 3G1 117 3.8 Atterberg Limits 3H 117 3.8.1 Liquid Limit 3H1 117 3.8.2 Plasticity Index 3H2 117 v Method Page code 4 Soil and Water Chemical Extractions and Analyses 4 119 4.1 Ion Exchange and Extractable Cations 4B 120 4.1.1 Cation-Exchange Capacity 4B1 121 4.1.1.1 NH4OAc, pH 7 (CEC-7) 4B1a 124 4.1.1.2 Sum of Cations (CEC-8.2) 4B4b1 125 4.1.1.3 NH4Cl, Neutral Unbuffered 4B1b 129 4.1.1.4 NH4OAc Extractable Bases + 1 N KCl Aluminum 4B4b2 129 4.1.2 NH4OAc, pH 7.0 Extractable Bases 4B1a1b 130 4.1.2.1–4 Calcium, Magnesium, Potassium, and Sodium 4B1a1b1–4 131 4.1.3 BaCl2-Triethanolamine, pH 8.2 Extractable Acidity 4B2 137 4.1.4–4.1.5 1 N KCl Extractable Aluminum and Manganese 4B3 139 4.1.6 Ratios, Estimates, and Calculations Related to Ion 4B4 141 Exchange and Extractable Cations 4.1.6.1 Sum of Extractable Bases 4B4a 141 4.1.6.1.1 Sum of Extractable Bases by 4B4a1 141 NH4OAc, pH 7 4.1.6.1.1.1 Sum of Extractable Bases 4B4a1a 141 by NH4OAc, pH 7, Calculated 4.1.6.1.2 Sum of Extractable Bases by NH4Cl 4B4a2 142 4.1.6.1.2.1 Sum of Extractable Bases 4B4a2a 142 by NH4Cl, Calculated 4.1.6.2 Cation-Exchange Capacity (CEC) 4B4b 142 4.1.6.2.1 CEC-8.2 (Sum of Cations) 4B4b1 142 4.1.6.2.1.1 CEC-8.2, Calculated 4B4b1a 142 4.1.6.2.1.2 CEC-8.2, Not Calculated 4B4b1b 142 4.1.6.2.2 Effective Cation-Exchange Capacity 4B4b2 142 (ECEC) 4.1.6.2.2.1 Sum of NH4OAc Extractable 4B4b2a 142 Bases + 1 N KCl Extractable Aluminum, Calculated 4.1.6.2.2.2 Sum of NH4OAc Extractable 4B4b2b 142 Bases + 1 N KCl Extractable Aluminum, Not Calculated 4.1.6.3 Base Saturation 4B4c 143 4.1.6.3.1 Base Saturation by NH4OAc, pH 7 (CEC-7) 4B4c1 144 4.1.6.3.1.1 Base Saturation by CEC-7, 4B4c1a 144 Calculated 4.1.6.3.1.2 Base Saturation by CEC-7, 4B4c1b 144 Set to 100 Percent 4.1.6.3.2 Base Saturation by NH4Cl 4B4c2p 145 4.1.6.3.2.1 Base Saturation by 4B4c2a 145 NH4Cl, Calculated vi Method Page code 4.1.6.3.2.2 Base Saturation by NH4Cl, 4B4c2b 145 Set to 100 Percent 4.1.6.3.3 Base Saturation by CEC-8.2 (Sum of 4B4c3 145 Cations) 4.1.6.3.3.1 Base Saturation by CEC-8.2, 4B4c3a 145 Calculated 4.1.6.3.3.2 Base Saturation by CEC-8.2, 4B4c3b 145 Not Calculated 4.1.6.3.4 Base Saturation by Effective 4B4c4 146 Cation-Exchange Capacity (ECEC) 4.1.6.3.4.1 Base Saturation by Sum of 4B4c4a 146 NH4OAc Extractable