BIBLIOTHEEK Nitrate Leaching from Non-Grazed Grassland Osimiy*Äspbouw Experimental Data for Testing of Simulation Models

BIBLIOTHEEK Nitrate leaching from non-grazed grassland oSIMiy*ÄSpBOUW experimental data for testing of simulation models

A Dutch contribution toth e EC project 'Nitrate insoils '

EJ . Jansen

0000 0521 5658 c * KB. ®93

DLO Winand Staring Centre, Wageningen (The Netherlands), 1991 rV I u ',-/J » ABSTRACT

E.J. Jansen, 1991.Nitrate leachingfrom non-grazedgrassland on a sandysoil: experimental data for testing of simulationmodels; a Dutch contributionto the ECproject 'Nitrate in soils'. Wageningen (The Netherlands), the DLO Winand Staring Centre. Report 26. 67 p.; 16 figs.; 15 tables; 22 ref.

Within the EC-project 'Nitrate in soils' research groups in six different countries carried out studies on nitrogen transport and transformation processes in soil and groundwater. One of the main purposes of the project was the evaluation of available nitrogen simulation models,usin g experimental datao f field studies, mainly focussed onnitrat e leaching. One of thedataset s used ispresente d in thisrepor t andconsist s of data from a field study of a non-grazed grassland system with application of both cattle slurry and mineral fertilizer. Thedatase tcomprise s timeindependen tbackgroun ddat aa swel l as timeserie s of datao nphysica l parameters andnitroge n fluxes.

Keywords: cattle slurry, field study, grassland, hydrology, manure injection, mineral fertilizer, nitrate leaching, nitrogen, sandy soil.

ISSN 0927-4537

The DLO Winand Staring Centre is continuing the research of: Institute for Land andWate r Management Research (ICW), Institute for Pesticide Research, Environment Division (IOB), Dorschkamp Research Institute for Forestry and Landscape Planning, Division of Landscape Planning (LB), and Soil Survey Institute (STIBOKA).

No parto f this publication mayb e reproduced orpublishe d in anyfor m orb y anymeans , orstore di n adat a base or retrieval system, without the written permission of the DLOWinan d Staring Centre.

Project 155.11 [JEJ] CONTENTS

Page

PREFACE 9

SUMMARY 11

1 INTRODUCTION 13

2 DESCRIPTION OF THE EXPERIMENT 15 2.1 Objectives of the experiment 15 2.2 Lay-out of the experiment 15 3 SITE INFORMATION 19 3.1 Location of the experimental field 19 3.2 Geohydrology of the area 22 3.3 Land use 22 3.4 Soil profile 23 3.5 Water retention characteristics 23 3.6 Hydraulic conductivity 24 3.7 Soil chemical data and particle size distribution 25

4 MONITORING OF PHYSICAL PARAMETERS 27 4.1 Meteorology 27 4.2 Evapotranspiration 29 4.3 Soil moisture contents 29 4.4 Soil temperature 31 4.5 Groundwater table 31

5 MONITORING OF NITROGEN FLUXES 33 5.1 Fertilizer management 33 5.2 Nitrogen in the crop 36 5.3 Mineral nitrogen in the soil 37 5.4 Nitrate leaching 39 5.5 Nitrogen concentrations in the deeper groundwater 40 5.6 Atmospheric deposition 40

REFERENCES 41

ANNEX 1 File with the general background data 43 2 Example of a file with water retention characteristics 45 3 File with hydraulic conductivity data 47 4 File with soil chemical data and particle size distribution 49 5 File with meteorological data 51 6 File with évapotranspiration data 53 7 Example of a file with soil moisture content data 55 8 File with soil temperature data 57 9 Example of a file with groundwater level data 59 10 Example of a file with management data 61 11 Example of a file with crop data 63 12 Example of a file with soil mineral nitrogen data 65 13 Example of a file with nitrate concentration data 67 FIGURES 1 Design of the experimentalfield nea r Ruurlo 16 2 Cross-section of part of the equipment for injection of slurry into the soil 17 3 Map of The Netherlands 19 4 Topographic map of the area south of Ruurlo, indicating the location of the experimental field 20 5 Plan of the experimental field near Ruurlo with the location of the different plots and the location and depths of the ditches 21 6 Simplified geological profile of East Gelderland 22 7 Water retention curves of four layers at the experimental field near Ruurlo 23 8 Hydraulic conductivity curves for the two functional layers occurring at the Ruurlo experimental site 25 9 Mean air temperatures in the years 1980-1985a t the Meteorological Station Almen 27 10 Precipitation at the experimental field nearRuurl o in the years 1980, 1981 and 1984 28 11 Penman open water evaporation in the years 1980-1985 at the Meteorological Station Winterswijk 29 12 Moisture contents in the rootzone and in the layer 0-100 cm-soil surface at field3 7 atth e Ruurlo experimental site as measured in the years 1980-1982 30 13 Soil temperature at three different depths at the Ruurlo experimental site as measured in the years 1980-1983 30 14 Groundwater level during the experimental period (1980-1985) at the Ruurlo experimentalfield, plo t number 37 31 15 Time series of mineral nitrogen content in the top 100c m of the soil at plot numbers 30 and 37 at the Ruurlo experimental field 38 16 Installation of four ceramic cups at adept h of approximately 1 meter to sample the percolating soil water 39

TABLES 1 Planned application rates of cattle slurry atth e experimentalfield nea r Ruurlo 15 2 Planned application rates of mineral-N fertilizer and the distribution overth e individual grass cuts during the growing season for the different N-levels at the experimental field near Ruurlo 16 3 Numbers of plots, indicating the combinations of mineral-N fertilizer level and cattle slurry application, on which nitrate leaching has been studied at the experimental field near Ruurlo 17 4 Some physical properties of the soil at the Ruurlo experimental site,use d for classification of functional layers 24 5 Some chemical soil properties of different layers at the Ruurlo experimental site 26 6 Groundwater level at each experimental plot relative to the groundwater level at plot number 56 and distances of all plots to the ditches 32 7 Dates of application of mineral-N fertilizer at the experimental field at Ruurlo prior to each grass cut 33 8 Amount of mineral-N fertilizer applied prior to each grass cut for each N-level at the Ruurlo experimental field 33 9 Dates of application and amounts of phosphate, potassium and magnesium applied with mineral fertilizer at the Ruurlo experimental field 34 10 Dates and technique of application of cattle slurry and actual amounts applied on the different treatments at the Ruurlo experimental field 35 11 Average content of dry matter, organic matter, total-N, ammonium-N, phosphate, and potassium of the applied cattle slurry 35 12 Harvest dates of grass cuts at the Ruurlo experimental site for each year 36 13 Annual N-uptake by the grass (harvested part only) for each year of the plots where leaching has been studied at the Ruurlo experimental site 37 14 Initial mineral-N content of different layers for each groupo f plots atth e Ruurlo experimental field, sampled on 12-3-1980 at the start of the experiment 38 15 Annual N-leaching of the studied plots for each year 40 PREFACE

In the EC-project 'Nitrate in soils', carried out during the years 1988-1990, several datasets of field studies were used for the evaluation of available nitrogen simulation models. One of these datasets consists of data of an experiment near Ruurlo in the Netherlands, and was made available by the DLO Winand Staring Centre. The draft version ofthi sdatase tha sbee ndistribute d amongth eparticipant so f theprojec t 'Nitrate in soils' in 1989, whilst additional information on the site was supplied in 1990. Therefore, already since that time,th e datahav e been used in simulation studies. Sinceonl y abrie f summary of theuse d datai sinclude di nth efina l report ofth e project (CEC, 1991),a separate report isno w issued containingth efina l version of the dataset. Compared to the draft version, this definitive version of thedatase t has been extended with datao f additionalplots . Besidesth eDL OWinan d StaringCentre ,th edat acompile d inthi srepor twer ecollecte d by several other intitutes: - Institute for Soil Fertility, Haren,(IB) ; - the Dutch Fertilizer Institute (NMI); - Centre for Agrobiological Research, Wageningen, (CABO) ; - Research Station for Cattle, Sheep and Horse Husbandry, Lelystad (PR). Their contribution to this dataset is greatly acknowledged. For a clear understanding of the description of the dataset in this report and the accompanying datafiles, it is recommended also to consult the report on the standardization of datafiles by Kragt &Janse n (1991).

If not enclosed in this report, the data can be obtained on a diskette by contacting the following adress:

The DLOWinan d Staring Centre for Integrated Land, Soil and Water Research, Department of Environmental Protection P.O. Box 125 6700A C Wageningen The Netherlands

Phone: +31837074200 Fax: +31837024812 Telex: 75230VISI-N L SUMMARY

The EC-project 'Nitrate in soils' included research on field measurements and on simulation of nitrogen transport and transformation processes in soil and groundwater. One of the main purposes of the project was the evaluation of different nitrogen simulation models, covering arang e of different modelling approaches.

The evaluation of the models was mainly focussed on nitrate leaching. Data of several field studies,includin ga rang eo fdifferen t soils,hydrologica lcondition s andagricultura l practices, have been used for this evaluation.

One of these datasets, presented here, consists of experimental datafro m afiel d study of a non-grazed grassland system on a sandy soil near Ruurlo,Th e Netherlands. The experimentha sbee nconducte di nth eyear s 1980-1985 asa join tprojec t ofsevera lDutc h institutes.

The dataset includes basic input data for the simulation models as well as data for comparison with simulation results. It comprises the following time independent background data: - description of the experiment, - location of the experimental field, - geohydrology of the area, - land use, - soil profile description, - water retention characteristics, - hydraulic conductivity data, - soil chemical data, - nitrogen concentration in the deep groundwater, - atmospheric deposition, and the following time series of monitored data: - meteorology (precipitation, temperature,etc.) , - évapotranspiration, - soil moisture content, - soil temperature, - groundwater table, - fertilizer management, - crop yield andN-uptake , - mineral nitrogen in the soil, - nitrate leaching.

11 1 INTRODUCTION

The EC-project 'Nitrate in soils', carried out during the years 1988-1990, included research on field measurements and on simulation of nitrogen transport and transformation processes in soil and groundwater, conducted bysevera l research groups in six different countries.

Oneo fth emai npurpose so fth eprojec twa sth eevaluatio no fdifferen t availablenitroge n models by the participating research groups. The available simulation models are all different in approach andhav e different levelso f complexity (Vereeckene t al., 1991b). Theevaluatio no fth emodel swa smainl yfocusse d onnitrat eleaching ,bu tattentio nwa s also paid to other important terms of the nitrogen balance, such as plant uptake and mineralization (Vereecken et al., 1991a).

Datao f severalfield studies ,includin ga rang eo f different soils,hydrologica l conditions and agricultural practices, have been used for the evaluation of the models. These datasets have been summarized by Breeuwsma et al. (1991). One of these datasets consists of experimental data from afield stud y of a non-grazed grassland system ona sandy soil at Ruurlo,Th e Netherlands.

The experiment was conducted in the years 1980-1985 as a joint research of the following Dutch institutes: - Institute for Soil Fertility, Haren (IB); - The Dutch Fertilizer Institute, Den Haag (NMI); - Centre for Agrobiological Research, Wageningen (CABO); - Research Station for Cattle, Sheep and Horse Husbandry, Lelystad (PR); - The DLO Winand Staring Centre for Integrated Land, Soil and Water Research (SC- DLO);

In this report the dataset isdescribed . At first agenera l description of theexperimen t is given in Chapter 2.Th e actual data andth e datafiles inwhic hth e datahav ebee n stored are described subsequently in Chapters 3 (site information), 4 (monitoring of physical parameters) and 5 (monitoring of nitrogen fluxes). Examples of the datafiles are given in the Annexes. The names and format of the presented datafiles comply with the standardization as listed by Kragt &Janse n (1991).

13 2 DESCRIPTION OF THE EXPERIMENT

2.1 Objectives of the experiment

In the years 1980-1985 an experiment was carried out near Ruurlo on a permanent grassland field. The objectives of this research were to study the effects of application of cattle slurry in combination with mineral fertilizers on utilization of the nitrogen in the slurry by grass (dry matter production, N-uptake), grass quality, botanic composition of the grass sward, soil fertility and nitrate leaching. Also differences between surface application and injection of the slurry have been studied, since injection of slurry might be a favourable technique for reducing losses of ammonia by volatilization. It has to be noted that the primary goal of the leaching study was the quantification of nitrate leaching, rather than the collection of data for the use in model studies.

The experiment at the Ruurlo site was one of a series of identical experiments at different sites in The Netherlands (Snijders et al., 1987; Van der Meer et al., 1987). The other experiments, however, have been studied less intensive, i.e. no nitrate leaching has been measured on these sites.

2.2 Layout of the experiment

The experimental field has been designed in such a way that 32 different treatments (plots) were laid out, i.e. combinations of amount of slurry, application technique of slurry and amount of mineral fertilizer N. Each treatment occurred in triplicate. The planned amounts of slurry and mineral fertilizer N applications are shown in Tables 1 and 2 respectively. A plan of the experimental field is shown in Fig. 1. A cross-section of the equipment for injection of slurry is shown in Fig 2.

The entire experimental field measures 69x60 m. Each individual plot has alengt h of 15 m and a width of 2.5 m, occupying an area of 37.5 m2, and has been divided in three parts. One part was used for crop research only, another part was used for soil sampling only, and the third part was used for measurements on nitrate leaching and soil moisture contents.

Table 1 Planned application rates ofcattle slurry atthe experimental field nearRuurlo, The Netherlands

Field code (Fig. 1) Application technique Amount (tonnes.ha'.yr1)

0+ injection* 0 20i injection 20 40i injection 40 80i injection 80 0b surface application 0 10b surface application 10 20b surface application 20 40b surface application 40

*: passage of injection equipment only

15 Table 2 Planned applicationrates of mineral-N fertilizer and the distribution over the individual grass cuts during the growingseason for the differentN-levels at the experimentalfield near Ruurlo, The Netherlands

N-level Planned application rate of fertilizer-N (kgJia-'.yr-1) (field code) cut 1 cut 2 cut 3 cut 4 cut 5 cut 6 total

NO 0 0 0 0 0 0 0 Nl 50 40 40 30 20 20 200 N2 100 80 80 60 40 40 400 N3 150 120 120 90 60 60 600

For practical reasons, only few plots have been used for the measurement of nitrate leaching as listed in Table 3. The results of the leaching study have been reported separately by Fonck (1982a, 1982b, 1986a, 1986b, 1986c).

69,00m 72 IN 80 2N 88 ON 96 3N 40b 71 3N 79 ON 87 2N 95 1N 20' 70 2N 78 3N 86 IN 94 ON 40' 69 ON 77 1N 85 3N 93 2N 80' III 68 1N 76 2N 84 ON 92 3N 0 67 2N 75 3N 83 IN 91 ON 20b 66 ON 74 1N 82 3N 90 2N 10b 65 3N 73 ON 81 2N 89 IN 0+ b 40 1N 48 3N W//A 56 ON » 64 2N « 40 39 2N « 47 ON 55 IN 63 3N 40' 38 ON 46 2N 54 3N 62 IN 0+ II 37 3N W///, 45 IN 53 2N W//, 61 ON 0 60 m 36 ON 44 2N 52 3N 60 IN 10b 35 2N 43 ON W& 51 IN 59 3N 80' 34 3N 42 IN 50 2N 58 ON 20' 33 IN 41 3N 49 ON 57 2N 20b 8 ON 16 2N V///A 24 3N V///A 32 IN 80' 7 IN 15 3N 23 ON 31 2N 20b 6 3N 14 1N 22 2N 30 ON W/A 0 5 2N 13 ON 21 IN 29 3N 10b 4 3N 12 2N 20 IN 28 ON 40b 3 2N 11 3N Wfa 19 ON » 27 IN 40' 2 IN 10 ON 18 3N 26 2N 0+ ON 2N 3N V 1 9 IN 17 25 20' 16,5 m

Fig.1 Design ofthe experimentalfield nearRuurlo (fieldcodes have been explainedin Tables 1 and 2) Legend:1-96 = plot number, IN -3N = mineral-Nfertilization level, Mill = plot where nitrate leaching hasbeen studied.

16 Table 3 Numbers of plots, indicating the combinations of mineral-N fertilizer leveland cattle slurry application, on which nitrate leaching has been studied at the experimental field near Ruurlo (i = injection, b = surface application)

Amount of Amount of mineral-N fertilizer (kg.hax N) cattle slurry (mMia-1) 0 200 400 600

Oi 20i 40i 19 39 11 80i 43 16 24 0b 30 53 37 10b 20b 40b 56 64 48

Slurry Slurry Slurry

-50 cm-

Driving 20 cm direction Slurry-

Front view Side view

Fig. 2 Cross-section of part of the equipment for injection of slurry into the soil

3 SITE INFORMATION

In this chapter the time independent background data of the site are presented. Part of the information from sections 3.1 through 3.4 can be found in the file NLRU000.GEN (Annex 1).Th e other background data have been listed in separate datafiles as indicated in each section. The names and format of the datafiles comply with the standardization given by Kragt & Jansen (1991).

3.1 Location of the experimental field

Fig. 3 shows a map of the Netherlands and the location of the area shown in Fig 4. Fig. 4 shows the location of the experimental field. The field is located at about 5 kilometers south of Ruurlo, the Netherlands at 52°02'00" northern latitude and 6°28'00" eastern longitude at an altitude of 18.0 m above sealevel.

Apart from some irregularities in the soil surface no significant slope can be detected in the field. The field is surrounded by ditches of approximately 1 meter depth; no tile drains have been installed. Fig. 5 shows an outline of the experimental field, including the position of the different plots within the field and the position and depth of the ditches.

G=T

Fig.3 Mapof The Netherlands indicating the areaenlarged inFig. 4

19 /erwf'i ii k"ipt" r,r •>. H ,e ..-.••»' ' *' ""v » Ihr ^ ' * Srmkmansbo^k' -"ete n Stuw

i<î "" .. «."«^

2 i't ? •-'•"" V" ' .* % '" ... ; X :- t'>p

",'De Brut! -0»A<» '•'' hoonlPliiK-p Btatk \

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- i ? t%. 1/ I ' . ' \ m 8 !M • Wi? 4,« . , X; '- - " '* 'b4 'i \ '''' ;*- -,,l "(Ti,'» Y»'"*' ,, ' V.- 6'

~:r , ., / ". . '- •* 1 fiiwriQSube* Br^eR v SA- Rsmm e ( . N t/

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:. v/(**f '•*(/ * , j •^ -• . Heurne . 180 %

veer

Halîe ^IHHI?1

2 km _| Fi^. 4 Topographie map of the area southofRuurlo, indicating thelocation of the experimentalfield (1:25 000)

20 Ditch, 1.05 m deep V/////////////////^^^^^

90 m

37 39

11 16 43 48

135 m 19 24 53 56

30 64

Ditch, 0.90 m deep

Road

Fig. 5 Planof theexperimental field near Ruurlo with thelocation of thedifferent plots and the location anddepth of theditches (100m = 15cm)

21 3.2 Geohydrology of the area

The geological formations of East Gelderland have been described by several authors (Ernst et al., 1970; Smoor & De Ridder, 1972; Grootjans, 1984). Fig. 6 shows a simplified geological profile of the area where the experimental field is located. The hydrological basis of the profile is formed by Tertiary deposits, occurring at a depth of 27 meters at the experimental site. During the Pleistocene these Tertiary deposits have beencovere d withpredominantl y coarse,gravel-bearin g sandso f fluvial and fluvioglacial origin, forming the aquifer. These deposits have been covered with fine windblown sand (Twente formation) with a much lower hydraulic conductivity than the Pleistocene sediments.

At the experimental site, the aquifer is 21 meters thick and covered with approximately 6 meters of windblown sand. The transmissivity of the aquifer, kD, is 3000 m2.day_1, so the average hydraulic conductivity is about 140 m.day'1. The hydraulic conductivity of the top layer is in the range of 1-1.5 m.day"1.

The general direction of regional groundwater flow, as derived from maps of water table isohypses, is approximately north-west with ahydrauli c gradient of 1: 500 0 (Bon, 1968; Smoor &D e Ridder, 1972).Th e groundwater in the aquifer isphreati c or semi-confined. Close to the experimental field a vertical flow resistance of the covering sand (c) of 25 days has been measured. Drainage resistances for the area have been estimated by Ernst et al. (1970) using an average radial flow resistance for the ditches of 0.9 day.m"1.

m 40 r- West Baak Hengelo Kloosterbos Ruurlo East -, 40 -Ussel Zelhem V"^ . 20 20

NAP - NAP

20 20 Tertiary deposits 40 - 40

60 O49C06 - 60

6km

Fig. 6 Simplified geological profileof EastGelderland, the areain whichthe experimental field atRuurlo is located (from:Smoor & De Ridder, 1972)

3.3 Land use

During the experiment the land has been used as apermanen t grassland without grazing. The grass has been mowed approximately six times a year. During the 5 years preceeding the experiment, the field has also been used as grassland, with "normal fertilization" for Dutch circumstances, i.e. a mineral fertilization including slurry application of 300-400 kg.haVyr1 N with grazing and some grass cutting for conservation.

22 3.4 Soil profile

The soil at the experimental field consists of a hydromorphic sand and can be classified as a Humic Gleysol, according to the FAO soil classification. It is a non-calcareous sandy soil with a distinct A-horizon of black loamy fine sand. It has a mottled zone (from gleyzation), which starts in the A-horizon and continues in the underlying C- horizon (Snijders et al., 1987). ,

The A-horizon is 17-22 cm thick (average is 20cm ) and contains approximately 5% clay and 5% organic matter; the median of the sand fraction (M50) is 90 pm^The C-horizon consists of (loamy) fine sand with 4% clay, and 0.1-0.5% organic matter; the median of the sand fraction (M50) is 140 um. Furthermore, at 60-80 cm below soil surface an iron- pan occurs, possibly disturbing vertical water movement.

The (potential) rooting depth is approximately 30cm ; inth e A-horizon root development is good, whereas beneath the A-horizon the possibilities for root development are only moderate.

3.5 Water retention characteristics

The water retention characteristics have been measured for 8 fields at 7 depths, e.g.: 5-10, 17.5-22.5, 30-35, 40-45, 50-55, 60-65 and 75-80 cm-soil surface. All presented data are averages of three replicates. Fig. 7 shows some water retention characteristics for plot number 37.

(a) (b)

OOO 0.70 C.20 0.30 0.40 0.50 06C 0 70 0.00 0.10 C.20 0.30 0.40 0.50 0.60 0.7Û

mo-sture fraction (cm3.cm'3) ^osture fraction (cm3,cm"3)

000 0 10 C.20 0.30 0.40 0.50 0.6C 070 OOO 0.10 C.20 0.30 O40 0.50 0.60 0.70

n-ioisture fraction (cm3.cm"3) moisture fraction {cm3.cm": Fig. 7 Water retention curves offour layers at the experimentalfield near Ruurlo, for plot number 37: 5-10 cm-soil surface (a), 12.5-17.5 cm-soilsurface (b), 25-30 cm-soil surface(c) and 60-65 cm-soil surface (d)

23 The available data are listed in the following files: NLRUOll.WRC NLRU024.WRC NLRU030.WRC NLRU037.WRC NLRU043.WRC NLRU048.WRC NLRU053.WRC NLRU064.WRC

The first page of such a dataffie with water retention characteristics (NLRU037.WRC) is given as an example in Annex 2.

3.6 Hydraulic conductivity

The hydraulic conductivity has not been measured for this experimental field either for saturated conditions, nor for unsaturated conditions. Therefore, data had to be derived from other sources. For soils in the Netherlands a standard soil series (Staringreeks) has been developed, giving global information about soil physical properties with respect to water movement, especially for regional applications. For topsoils and subsoils 11 respectively 15differen t functional layers havebee n distinguished, based on particle size distribution and organic matter content (Wostcn et al., 1987).

In Table 4 the soil properties on which the classification is based, and the classification itself, is presented per layer of 10 cm at the Ruurlo experimental site. The upper 40 cm of the profile is classified as topsoil B3,th e lower part of the profile as subsoil 02. Fig. 8 showsth emea n hydraulic conductivity curveso f these functional layers withthei r 95% confidence interval.

Table 4 Some physical propertiesof the soil at the Ruurlo experimentalsite, used for classification offunctional layers according to Wasten etal. (1987)

Layer Organic Particles Bulk density Median of Functional (cm-ss) matter <50 um (g.cmf 3) particles layer ace. to (%) (%) >50 urn (urn) classification

0-10 6.9 32.3 1.2 130 B3 10-20 4.3 31.6 1.3 128 B3 20-30 0.8 34.6 1.5 113 B3 30-40 0.6 28.7 1.6 125 B3 40-50 0.4 11.8 1.7 160 02 50-60 0.5 16.3 1.7 160 02 60-70 0.1 11.5 1.7 137 02 70-80 0.2 12.3 1.7 154 02 80-90 0.2 12.4 1.7 154 02

24 (a) (b)

B3 02 Doorlatendheidskarakteristie k Doorlatendheidskarakteristiek 10'

10°

io-2

io-4

6 E 10' o

10'8

io-12

10-1"i- _L J 10° IO1 102 IO3 104 105 106 107 10° 10' 102 IO3 104 105 106 107 Ihl(cm) Ihl(cm)

Fig. 8 Hydraulicconductivity curves with95% confidence intervalfor the two functional layers occurring at the Ruurlo experimental site:topsoil B3 (a)and subsoil 02 (b); afterWasten etal. , 1987

Description of the topsoil functional layer B3(Woste n et al., 1987): - strong loamy, very fine to medium fine sand; - particles <50um : 18-33%; - organic matter: 0-15%; - median of sand fraction: 105-210urn ; - bulk density: 1.1-1.5 g.cm"3;

Description of the subsoil functional layer 02 (Wösten et al., 1987): - light loamy, very fine to medium fine sand; - particles <50urn : 10-18%; - organic matter: 0-3%; - median of sand fraction: 105-210urn ; - bulk density: 1.5-1.7 g.cm"3;

The hydraulic conductivity data are listed in file NLRU000.HCU. The first page of this file is shown in Annex 3.

3.7 Soil chemical data and particle size distribution

At the start of the experiment in 1980 some basic chemical data of the soil were gathered, i.e. organic matter content, organic N content, pH(KCl) and bulk density per soil horizon. Table 5 shows the results of these measurements.

25 Table 5 Some chemical soilproperties of differentlayers at theRuurlo experimental site

Layer Organic matter Total-N pH(KCl) Bulk density (m-soil surf.) (%) (%) (kg.m3)

0.00-0.05 11.3 0.43 4.9 1.15 0.05-0.25 5.3 0.23 4.7 1.32 0.25-0.50 1.8 0.03 4.7 1.66 0.50-0.75 1.9 0.02 5.4 1.73 0.75-1.00 1.1 0.01 6.2 1.71

The organic matter content (% OM) has been measured as loss of weight from an air- dried soil sample after heating (500 °C), the percentage organic carbon (% C) can then be calculated from:

%C = %OM * 0.57

The amount of total nitrogen has been measured by destruction of an air-dried soil sample in a concentrated phenol-sulfuric acid solution and analysis of the amount of ammonia in the extract.

Since the amount of mineral nitrogen is negligible compared to the amount of total nitrogen, the latter approximately equals the amount of organic nitrogen.

In this experiment pH(KCl) has been measured in a 1 M KCl solution. To calculate pH(H20) for this soil type, the following empirical relation is used (...): pH(H20) = 2.116 + 0.7262 * pH(KCl)

Furthermore aparticl e size distribution analysis has been carried out to establish the clay content (particles < 2 urn), the silt-content (particles 2-50 urn) and the sand-content (particles > 50 pm) of the mineral part of the different soil layers.

The data mentioned in this section have been listed in the datafile NLRU000.SCP (Annex 4).

26 4 MONITORING OF PHYSICAL PARAMETERS

In this chapter the results are presented of the monitoring of relevant physical parameters during the experiment at the Ruurlo site. Examples of datafiles are given in Annexes 5 through 9. In the datafiles with time series of monitored data daynumbers are given; daynumbcr 1 is at 1-1-1980. The names and format of the datafiles comply with the standardization given by Kragt & Jansen (1991).

Irrigation has not taken place during the experiment; therefore the file NLRU000.IRR is not included in the dataset.

4.1 Meteorology

The meteorological data supplied in this dataset originate from different sources. Air temperature data (daily averages) have been obtained from the meteorological station Almen, about 14 km northwest of the experimental field. The temperature has been measured at a height of 2 m above soil surface. Fig. 9 shows the mean air temperature during the entire five year period of the experiment. Precipitation has been measured every day near theexperimenta l field. In Fig. 10example s of daily precipitation amounts in three different years are presented. Global radiation data have been obtained from a meteorological station approximately 100 km north of the experimental field. Because of this large distance these data only give an indication of the local global radiation.

The meteorological data are listed in file NLRU000.CLI; the first page of this file is shown in Annex 5.Th e daily minimum and maximum air temperatures are not provided (value 99. in the datafile); also data on mean wind velocity and mean relative humidity have not been included (value -1. in the datafile).

ü o 0) b

365 730 1095 1460 1825

time(days ) Fig.9 Mean air temperatures in theyears 1980-1985 at theMeteorological Station Almen (daynumber 1 = 1-1-1980)

27 40

(a)

30 (C T3

o 20 ro 5. u CD a 10

J I •Ii Ltil l 90 180 270 360 time (days) 40 (b)

30 >, to Ë c o 20

JL J mu ii y Hit inii,ij , 731 821 91 1 1001 109- time (days) (C) 40

T 30 > ro "ö É E B 20

o JJ .11 «IIn l nil IIIA 1461 1551 1641 173' 1821 time (days) Fig. 10 Precipitation atthe experimental field nearRuurlo inthe years 1980 (a),1982 (b) and 1984 (c);daynumber 1= 1-1-1980

28 60

o 30 a ca IUI > CD c 20 r ro Q 10 mil III IH ,| 0 lilllllllllllillllllill 0 366 731 1096 1461 1827 time(days ) Fig. 11 Penmanopen waterevaporation inthe years 1980-1985 atthe MeteorologicalStation Winterswijk (daynumber 1= 1-1-1980)

4.2 Evapotranspiration

Data on open water evaporation according to Penman have been obtained from the Meteorological Station Winterswijk (20 km east of the experimental site); cumulative values (mm) for ten day periods are given. Potential évapotranspiration can be calculated using crop specific reduction factors (Feddes, 1987). Usually a value of 0.8 is used for grassland. Fig. 11 shows the evaporation during the five years of the experiment. The évapotranspiration data are listed in file NLRU000.ETR; the first page of this file is shown in Annex 6.

4.3 Soil moisture contents

Soil moisture contents in different soil layers were derived from gamma-transmission measurements. In this way the wet bulk density ismeasure d in the field and the moisture content is calculated as the difference between the dry and the wet bulk density. Measurements have taken place at irregular time intervals. Due to technical problems only 3 years of measurements could be obtained. An example of the results is given for plot number 37 in Fig. 12.

The available data have been listed in the following files: NLRU011.SMO NLRU024.SMO NLRU030.SMO NLRU037.SMO NLRU043.SMO NLRU056.SMO

29 JJU - ? 300 - *\ P~ - -

270 \ ' i - * \; E 240 ~ E V 210 \ c i - A Sc 1B0 0 0 150 CU D 120 (J) > 0 90 E _ + 60 + V 30 -

i i i 300 600 1200 time (days)

-+-- layer 0-30 --&-- layer 0-100 cm-surface cm-surface Fig. 12 Moisture contents inthe rootzone (0-30 cm-soilsurface) andin the layer0-100 cm-soil surface atfield 37 at the Ruurlo experimentalsite asmeasured inthe years 1980-1982 (daynumber 1= 1-1-1980)

\J f «t+T " • fè e^î+A CD _ + 15 8 *9Pê i * in o c C CD 0 1 , E Ï (|) 1<> of+ - A

ÔA (Ju) .

300 600 900 1200 1500 time (days)

+ 5 cm depth A 15 cm depth 30 cm deoth Fig. 13 Soiltemperature atthree differentdepths (0,15 and30 cm-soil surface) atthe Ruurlo experimental siteas measured in theyears 1980-1983 (daynumber 1 = 1-1-1980)

30 The first page of a file with soil moisture contents (NLRU037.SMO) is given as an example in Annex 7.

4.4 Soil temperature

The soil temperature (°C) has been measured at three places in the field at three depths (5, 15 and 30 cm-soil surface). Measurements have been carried out from 1980 to 1983. Averages of measured temperature per depth have been supplied in the file NLRU000.STE. Annex 8show s the first page of this file, whilst in Fig. 13a presentation of the data is given.

4.5 Groundwater level

At all fields piezometers have been installed to measure the depth of the phreatic groundwater level. The monitoring frequency ranges from once a week to once a month throughout the entire experimental period. Data are listed in the following files: NLRU011.GWL NLRU016.GWL NLRU019.GWL NLRU024.GWL NLRU030.GWL NLRU037.GWL NLRU039.GWL NLRU043.GWL NLRU048.GWL NLRU053.GWL NLRU056.GWL NLRU064.GWL

0.00 _ - A en ~ ! \ + \ CO X A I 0.50 ~ + 1 i * ' i A ; ;

1.00 , \ ; ^ I 1 + ' + >* 1 "O * f' \ * + c *\* i D 1.50 O - \ - ^ - , 2.00 i i i 0 365 730 1095 1^60 1825

time (days) Fig.14 Groundwater level during the experimental period (1980-1985) at theRuurlo experimentalfield, plotnumber 37 (daynumber 1 = 1-1-1980)

31 The first page of a file with groundwater level data (NLRU037.GWL) is shown as an example in Annex 9. An example of the course of the groundwater level during the experimental period is given in Fig. 14 for field number 37.

Differences in groundwater levels among the different plots, as measured relative to the soil surface, are small and very constant. The groundwater level of plot number 56 can be regarded as an average value for the entire experimental field; in Table 6 the depth of the groundwater level of the other plots is given relative to the level at plot 56. The differences in groundwater level can be explained entirely by differences inheigh t of the soil surface. Relative to a reference height all groundwater levels arc equal (Fonck, 1986c). Therefore no detectable horizontal hydraulic gradient exists in the field. Apparantly, the distances to the ditches of the plots used for monitoring of nitrate leaching, shown in Table 6, are too large to cause a convex groundwater table at these plots. Therefore, no evidence exists that lateral flow to the ditches through the shallow groundwater at the experimental site takes place.

Due to the small vertical resistance (see Chapter 3.2), the differences between the hydraulic head of the deep groundwater (10 m) and the hydraulic head of the shallow groundwater is very small. Values ranging between 0.0 and 0.5 cm have been measured, resulting in a small downward flux. However,judgin g from the fast rises in groundwater level which occur sometimes, seepage during some periods cannot be excluded.

Table6 Groundwater level ateach experimentalplot relative tothe groundwater levelat plot number56 and distances of allplots to the ditches (see alsoFig. 5)

Plot Relative Distance (m) to ditches number groundwater level (cm-ss) north west south

11 -4 68 68 60 16 +3 68 58 60 19 +10 52 68 77 24 +9 52 58 77 30 +6 35 63 94 37 -7 85 46 44 39 -7 85 39 44 43 -3 68 51 60 48 -2 68 36 60 53 +3 52 46 77 56 0 52 36 77 64 +10 35 36 94

32 5 MONITORING OF NITROGEN FLUXES

5.1 Fertilizer management

In the experiment mineral-N fertilizer has been applied at the beginning of the growing season and after each grass cut. The dates of application of mineral-N fertilizer are listed in Table 7. The first and second application of each year has been as MAS-22% (11% NH4-N, 11%N0 3-N), all other applications as KAS-26% (13% NH4-N, 13% N03-N). The actual amount of N (kg.ha1) supplied with mineral fertilizer is shown for the different N-levels in Table 8.

Table7 Datesof application of mineral-Nfertilizer at the experimentalfield near Ruurlo priorto each grass cut

Year cut 1 cut 2 cut 3 cut 4 cut 5 cut 6 cut 7

1980 24-03 07-05 29-05 25-06 29-07 19-08 17-09 1981 16-04 22-05 19-06 14-07 05-08 08-09 1982 06-04 14-05 02-06 09-07 11-08 1983 22-04 31-05 21-06 15-07 06-09 1984 02-04 23-05 14-06 11-07 09-08 18-09

Table 8 Amount ofmineral-N fertilizer applied prior toeach grass cutfor each N-levelat the Ruurlo experimental field

Year N-level Amount of mineral-N fertilizer applied (kg.ha1)

cut 1 cut 2 cut 3 cut 4 cut 5 cut 6 cut 7 total

1980 NO 0 0 0 0 0 0 0 0 Nl 50 40 40 30 20 20 20 220 N2 100 80 80 60 40 40 40 440 N3 150 120 120 90 60 60 60 660 1981 NO 0 0 0 0 0 0 0 Nl 50 40 40 30 20 20 200 N2 100 80 80 60 40 40 400 N3 150 120 120 90 60 60 600 1982 NO 0 0 0 0 0 0 Nl 50 40 40 15 20 165 N2 100 80 80 30 40 330 N3 150 120 120 45 60 495 1983 NO 0 0 0 0 0 0 Nl 50 40 40 30 20 180 N2 100 80 80 60 40 360 N3 150 120 120 90 60 540 1984 NO 0 0 0 0 0 0 0 Nl 50 40 40 30 20 20 200 N2 100 80 80 60 40 40 400 N3 150 120 120 90 60 60 600

33 Table 9 Datesof application and amounts (in kg.ha'.yf') of phosphate (P205), potassium (K20) and magnesium (MgO) applied with mineral fertilizer at the Ruurlo experimental field

Year Date P205 K20 MgO

1980 <13-03 84 144 29-05 70 120 29-07 56 96 19-08 56 1981 24-024-03 3 808 0 10010 0 50 22-05 100 19-06 80 14-07 80 05-08 80 08-09 80 1982 30-030-03 3 808 0 10010 0 50 14-05 100 02-06 80 09-07 80 11-08 80 1983 22-04 40 70 21-06 70 15-07 70 31-10 70 1984 16-03 45 130 23-05 90 14-06 90 11-07 45 90 09-08 90 18-09 90

In order to study the effect of nitrogen separately, side effects due to deficiencies of othernutrient s havebee nexcluded . Therefore, optimum conditions havebee n maintained throughout the entire experimental period for all nutrients other than N.Th e amounts of P and K supplied with mineral fertilizer as well as the dates of application are presented in Table 9.

Each year in spring, cattle slurry has been applied on the field either by injection or by surface spreading. The actual amount of cattle slurry applied, the application technique and date of application areliste d inTabl e 10fo r each treatment. After surface application no incorporation of slurry in the soil by ploughing has taken place, therefore a certain amount of ammonia has volatilized. Amounts of ammonia lost by volatilization in the first five days after application can range from 14t o 62 %o f the ammonia present in the slurry, with an average of 35% depending on the actual weather situation and the composition of the slurry (Pain & Thompson, 1989). Injection of cattle slurr reduces volatilization to 0-5% of the ammonia in the slurry. The slurry was injected in the soil in rows with a distance of 50c m and at a depth of 20 cm- soil surface (see also Fig. 2).Th e fields have not been grazed, therefore no account has to be taken of animal excretions.

The contentso f the applied cattle slurry (drymatter ,organi cmatter , total-N,NH4 ,total- P and K) are given in Table 11 for each year of the experiment.

34 Table 10 Dates and technique of application of cattle slurry and actual amounts (kg.ha') applied on the different treatments at the Ruurlo experimental field

Year Date Application Field code Amount technique OPqbheal)

1980 18-03 Oi/Ob 0 injection 20i 24840 injection 40i 42000 injection 80i 80535 19-03 surface 10b 10480 surface 20b 20700 surface 40b 41800 1981 15-04 Oi/Ob 0 injection 20i 23790 injection 40i 41460 injection 80i 77854 surface 10b 9230 surface 20b 18460 surface 40b 33542 1982 01-04 Oi/Ob 0 injection 20i 18582 injection 40i 41710 injection 80i 78027 surface 10b 11544 surface 20b 21835 surface 40b 37720 1983 20-04 Oi/Ob 0 injection 20i 19698 injection 40i 36582 injection 80i 81780 surface 10b 11520 surface 20b 20160 surface 40b 33600 1984 29-03 Oi/Ob 0 injection 20i 21296 injection 40i 37752 injection 80i 75520 surface 10b 10212 surface 20b 19573 surface 40b 39524

Table 11 Average content of dry matter (DM), organic matter (OM), total-N, ammonium-N, phosphate (P2Oi) and potassium (K20) of the applied cattle slurry in g.kg'

Year DM OM Total-N NH3-N P2O5 K20

1980 104 78 4.8 . 1.9 6.3 1981 110 85 5.0 2.0 1.6 6.4 1982 111 84 5.2 2.4 1.8 6.4 1983 117 89 5.4 1.8 1.9 6.5 1984 101 77 4.0 1.3 1.5 5.2

35 The data on agricultural management are summarized for each plot in the following datafiles: NLRU011.MAN NLRU016.MAN NLRU019.MAN NLRU024.MAN NLRU030.MAN NLRU037.MAN NLRU039.MAN NLRU043.MAN NLRU048.MAN NLRU053.MAN NLRU056.MAN NLRU064.MAN

In these datafiles codes have been used for action (1 = addition) and for material type (1 = cattle slurry, 6 = mineral fertilizer). The first page of the file NLRU039.MAN is given as an example in Annex 10.

5.2 Nitrogen in the crop

Throughout the entire experimental period the soil was permanently covered with grass. The grass sward consisted of 70-90% English ryegrass (Loliumperenne L.) as derived from observations on botanic composition.

The criterion for cutting the grass was that on one hand the plots with the lowest yield could be mowed, whilst on the other hand on the plots with the highest yield the crop should not become too heavy. The harvest dates of the different cuts are shown in Table 12. For each cut the grass of 5.3 m2 was collected and analyzed for dry matter content and N-content. No measurements have been carried out on the amount and N-content of crop residues, such as harvest losses and root mass.

In Table 13 the annual N-uptake in the harvested part of the grass is presented of the plots for which the nitrate leaching has been monitored.

Table12 Harvest dates of grass cutsat the Ruurlo experimental sitefor each year

Year cut1 cut2 cut3 cut4 cut5 cut6 cut7

1980 06-05 28-05 24-06 24-07 19-08 17-09 23-10 1981 14-04 19-05 16-06 14-07 05-08 08-09 28-10 1982 11-05 01-06 06-07 10-08 13-10 1983 19-05 15-06 13-07 17-08 28-10 1984 15-05 07-06 05-07 02-08 11-09 07-11

36 Table13 AnnualN-uptake by the grass (harvestedpart only) for each yearof the plots where leaching has been studiedat the Ruurloexperimental site (after Snijders et al., 1987)

Plot N-uptakeb y theharveste dpar to fth egras s (kg.ha1) number 1980 1981 1982 1983 1984

11 707 567 474 550 611 16 667 558 460 535 591 19 241 281 244 223 204 24 698 525 453 571 612 30 125 180 130 129 163 37 633 580 432 501 593 39 623 563 486 543 529 43 376 407 369 323 271 48 637 624 412 522 590 53 528 506 373 440 471 56 166 220 178 183 181 64 533 559 434 444 525

The data on crop yields are summarized for each plot in the following datafiles: NLRU011.CRP NLRU016.CRP NLRU019.CRP NLRU024.CRP NLRU030.CRP NLRU037.CRP NLRU039.CRP NLRU043.CRP NLRU048.CRP NLRU053.CRP NLRU056.CRP NLRU064.CRP

In these datafiles codes have been used for crop type (1 = English ryegrass (Lolium perenne L.)) and action (1 = sowing, 3 = harvest (cutting)). Since the amount and N- content of crop residues were not measured in this experiment, all variables related to these measurements have been set to 0 in the datafiles. The first page of a file with crop data (NLRU037.CRP) is given as an example in Annex 11.

5.3 Mineral nitrogen in the soil

Soil samples for the analysis of mineral Nhav e been taken twice a year (before and after the growing season) from the layers 0-5, 5-25, 25-50, 50-75 and 75-100 cm-surface. Furthermore the layers 0-5, 5-25, 25-50 and 50-100 cm-surface have been sampled after every grass cut and before fertilizer application at all plots. Table 14 shows the initial mineral N contents of the soil at the start of the experiment, sampled on 12-3-1980. Fig. 15 shows an example of the course of the amount of mineral N in the soil profile 0-100 cm-soil surface for an unfertilized plot (plot 30) and a plot fertilized with 600 kg.ha"1.yr1 N mineral fertilizer (plot 37).

37 Table 14 Initialmineral-N content of different layersfor each group ofplots at the Ruurlo experimentalfield, sampled on 12-3-1980 at the startof the experiment; between brackets theamounts of NH/-N andN0 3'-N aregiven respectively

Layer Mineral N (kg.ha N per layer) in plot nrs. (m-soil surface) 11,16 19,24,30 37,39,43,48 53,56,64

0.00-0.05 16 (4+12) 16 (7+9) 12 (4+8) 17 (7+10) 0.05-0.25 13 (2+11) 8 (0+8) 11 (3+8) 11 (3+8) 0.25-0.50 8 (0+8) 8 (0+8) 8 (4+4) 4 (0+4) 0.50-0.75 13 (0+13) 17 (0+17) 13 (0+13) 9 (0+9) 0.75-1.00 17 (0+17) 17 (0+17) 17 (0+17) 13 (0+13)

The data on soil mineral N are listed for each plot in the following datafiles: NLRU011.SMN NLRU016.SMN NLRU019.SMN NLRU024.SMN NLRU030.SMN NLRU037.SMN NLRU039.SMN NLRU043.SMN NLRU048.SMN NLRU053.SMN NLRU056.SMN NLRU064.SMN

The first page of the file with data on soil mineral N (NLRU037.SMN) is given as an example in Annex 12. . il * II II - II M 300 | I 1 \ z. I I 1 \ I l 1 *• I I ro 1 \ 250 I I 1 \ I l 1 \ * A i I i \ / I 200 / l / \ i i I 1 V ID I i / \ i* \\ f I l 1 \ 0 I I i f) 150 \ r i \ I I r \ \ ' ^ i V ; \ / I \ l \ * \ ^ \ i ~rö 100 K \ ' Il i 1 x \ .- H1 l\ \ \ /' \ i r 1 M s \ \ / l ' ' A , i 1 1 \ i \/ E / \ \N A- -A t -le i 50 V \i i Y -/ \ A - '' *\ v / v i -t i "--/ . 4 _^- - " -~-j! , 1 Il ^ O 365 730 1095 1460 '825

time (days) --+-- field 30 —A— field 37 Fig. 15 Time series ofmineral nitrogen content inthe top 100 cmof the soilat plot numbers 30 (unfertilized) and37 (600 kg.ha'.yr' N) at theRuurlo experimental field

38 5.4 Nitrate leaching

Nitrate leaching has been measured by sampling the soil water with ceramic cups. At each plot 4 cups have been installed at a depth between 90 and 100 cm (Fig. 16). Bulk samples were taken from each plot by applying asuctio n of approximately 0.7 bar, using a hand operated pump. Sampling was carried out in the winter seasons only (months from October till May), being the period of the year with an expected precipitation surplus. The sampling frequency depended on the amount of precipitation surplus, i.e. a sample has been taken every time the water in the sampled layer was assumed to be replaced.

The amount of leached nitrate has been calculated from a simple water balance and the assumed linear change of the concentration between two sampling events. Results of these calculations for all plots and years are listed in Table 15.

The data on nitrate concentrations at 1 meter depth are listed for each plot in the following datafiles: NLRU011.LEA NLRU016.LEA NLRU019.LEA NLRU024.LEA NLRU030.LEA NLRU037.LEA NLRU039.LEA NLRU043.LEA NLRU048.LEA NLRU053.LEA NLRU056.LEA NLRU064.LEA

The first page of a file with nitrate concentration data (NLRU037.LEA) is given as an example in Annex 13.

Soil surface

Ceramic cup

Fig. 16 Installation offour ceramic cupsat a depthof approximately 1 meter tosample the percolating soilwater; (a) topview, (b)side view

39 Table15 Annual N-leaching of the studied plotsfor each year;after Fonck (1982a, 1982b, 1986a, 1986b, 1986c)

Plot N-leaching (kg .ha1) number 1980/'81 1981/'82 1982/'83 1983/'84 1984/'85

11 134.8 105.6 156.6 102.6 75.3 16 70.4 122.3 150.5 76.0 64.2 19 19.3 14.1 11.3 24.0 4.9 24 206.7 227.9 316.9 142.2 185.8 30 28.5 3.2 1.6 16.4 7.3 37 86.1 66.7 102.0 95.5 68.8 39 53.6 40.4 52.0 35.6 23.2 43 39.2 11.6 24.4 21.5 6.0 48 - 110.5 103.8 71.6 71.6 53 - 42.0 29.7 59.0 33.5 56 - 6.1 2.3 7.7 2.5 64 - 60.4 29.0 29.6 37.5

5.5 Nitrogen concentrations in the deeper groundwater

From data of anationwid e network for monitoring of groundwater quality, thenitrat e and ammonium concentrations in the deeper groundwater have been estimated (according to Gast et al., 1985). The following concentrations of nitrate and ammonium can be found at the experimental site at a depth of 10 meter below soil surface: 1 Nitrate: 2.5 mg.1 N0 3"-N 1 + Ammonium: 0.25 mg.1" NH4 -N

5.6 Atmospheric deposition

An important source of nitrogen in the soil is formed by atmospheric deposition; wet and dry deposition can be distinguished.

The amount of nitrogen via wet deposition depends on the amount of rainfall and the nitrogen concentrations in the rain. The Dutch institutes KNMI & RIVM (1987) have measured concentrations of nitrate and ammonium in precipitation. The average concentrations at a monitoring station close to the experimental field were: Nitrate: 2.53 mg.1"1 N Ammonium: 0.84 mg.1"1 N

For dry deposition the following data have been estimated from regional data of a research on acidification of the environment (according to Schneider & Brcsser, 1987): 1 1 Nitrate (NOx): 16.4 kg.ha .yr" N Ammonia: 18.0 kg.ha"1.yr1 N

40 REFERENCES

BON, J., 1968. 'Topografie en vorm van het grondwatervlak als achtergrond van de te verwachten afvoeren ind eGelders eAchterhoek" . Cultuurtechnisch tijdschrift 8:138-150.

BREEUWSMA, A., DJ. DJURHUUS, E.J. JANSEN, J.F. KRAGT, M.C.J.J. SWERTS & A.J. THOMASSON, 1991. "Datasets for validation of nitrate simulation models". In: CEC, 1991. Final report of the project: Nitrate in soils (Chapter 6).

CEC, 1991.Final report of theproject: "Nitrate in soils", Brussels, in press.

ERNST, L.F., N.A. DE RIDDER & JJ. DE VRIES, 1970. "Geohydrological study of East Gelderland (Netherlands)". Geologie en Mijnbouw 49: 457-488.

FEDDES, R.A., 1987. "Crop factors in relation to Makkink reference-crop évapotranspiration". In: Evaporation and Weather, CHO-TNO Proceedings and Information 39: 33-45.

GAST, L.F.L., J. TAAT & W. VAN DUIJVENBOODEN, 1985. Landelijk Meetnet Grondwaterkwaliteit; deelrapport 2. Concentratiekaarten van de eerste bemonstering. Bilthoven, RIVM. Rapport 840382002.

GROOTJANS, P., 1984. De geohydrologische beschrijving van deprovincie Gelderland. Delft, Dienst Grondwater Verkenning - TNO; Arnhem, Dienst Waterbeheer Provincie Gelderland.

KNMI & RIVM, 1987. Chemische samenstelling van de neerslag over Nederland. Jaarrapport 1985. Bilthoven, RIVM. Rapport 228703001.

KRAGT, J. & E.J. JANSEN, 1991.Standardization of datafllesfor testing of simulation models; a contribution to the EC-project "Nitrate in soils". Wageningen, The Netherlands, The DLO Winand Staring Centre. Report 25.

MEER, H.G. VAN DER, R.B. THOMPSON, P.J.M. SNÜDERS & J.H. GEURINK, 1987. "Utilization of nitrogen from injected and surface spread cattle slurry applied to grassland". In: H.G. VAN DER MEER et al. (eds.), Animal manure on grassland and fodder crops. Fertilizer or waste? Dordrecht, the Netherlands, Martinus Nijhoff Publ.: 47-71.

PAIN, B.F. & R.B. THOMPSON, 1989. "Ammonia volatilization from livestock slurries applied to land". In: J.AA. HANSEN & K. HENRKSEN (eds.):Nitrogen in organic wastes applied to soils. Academic Press, London: 202-212.

SCHNEIDER, T. & A.H.M. BRESSER (eds.), 1987. Dutch priority programme on acidification. Verzuringsonderzoek eerstefase. Bilthoven, RIVM.Tussentijds e evaluatie, augustus 1987, nr 00-04.

41 SMOOR, P.B. & N.A. DE RIDDER, 1972. Grondwaterkartering van Nederland - schaal 1 : 50 000; geohydrologische toelichting bij de kaartbladen34W Groenlo en41W Aalten. Delft, Dienst Grondwater Verkenning - TNO.

SNIJDERS P.J.M., JJ. WOLDRING, J.H. GEURING & H.G. VAN DER MEER, 1987. Stikstofwerking van geïnjecteerde runderdrijfmest op grasland. Verslag van onderzoek naar effecten van stikstof uit geïnjecteerde en bovengronds aangewende runderdrijfmest op opbrengst en kwaliteit van gras. Lelystad, PR. Rapport nr. 103.

VEREECKEN, H., E.J. JANSEN, M.J.D. HACK-TEN BROEKE, M. SWERTS, R. ENGELKE, S. FABREWTTZ & S. HANSEN, 1991a. Comparison of simulation results of five nitrogen models using different datasets. In: Commission of the European Communities, 1991. Nitrate in soils. Soil and Groundwater Research Report II. Luxembourg. 321-338.

VEREECKEN, H., M. SWERTS, M.J.D. HACK-TEN BROEKE, E.J. JANSEN, J.F. KRAGT, R. ENGELKE, S. FABREWTTZ & S. HANSEN, 1991b. Systematic comparison of model requirements and transformation processes. In: Commission of the European Communities, 1991. Nitrate in soils. Soil and Groundwater Research Report II. Luxembourg. 237-248.

WÖSTEN, J.H.M., M.H. BANNINK & J. BEUVING, 1987. Waterretentie- en doorlatendheidskarakteristieken van boven- en ondergronden in Nederland: De Staringreeks. Wageningen, ICW. Rapport 18. Wageningen, STIBOKA. Rapport 1932.

UNPUBLISHED SOURCES

FONCK H. 1982a.Stikstofconcentraties inbodemvocht engrondwater onder grasland op zandgrond in afhankelijkheid van runderdrijfmest- en kunstmeststikstofdosering. Wageningen, ICW. Nota 1337.

FONCKH . 1982b.Stikstofconcentraties in bodemvocht engrondwater onder grasland op zandgrond in afhankelijkheid van runderdrijfmest- en kunstmestdosering (2e onderzoeksjaar 198111982). Wageningen, ICW. Nota 1407.

FONCK H. 1986a. Stikstofconcentraties inbodemvocht engrondwater onder grasland op zandgrond in afhankelijkheid van runderdrijfmest- en kunstmestdosering (3e onderzoeksjaar 1982/1983). Wageningen, ICW. Nota 1707.

FONCK H. 1986b.Stikstofconcentraties in bodemvocht engrondwater onder grasland op zandgrond in afhankelijkheid van runderdrijfmest- en kunstmestdosering (4e onderzoeksjaar 1983/1984). Wageningen, ICW. Nota 1685.

FONCK H. 1986c.Stikstofconcentraties inbodemvocht engrondwater onder grasland op zandgrond in afhankelijkheid van runderdrijfmest- en kunstmestdosering (5e onderzoeksjaar 1984/1985). Wageningen, ICW. Nota 1690.

42 ANNEX 1 File with general background data

File: NLRUO00.GEN Code: ASCII Access: sequential Author: E.J. Jansen Version: 2 Date: 23-07-1991 Source: - **********************************************************************

'Ruurlo, The Netherlands' 52 02 00 'NL' 06 28 00 'EL' 0.0 18.0 37.5 'Ditches approx. 1mete r deep, surrounding the field' 'Humi c gleysol' 2 'A' 0.00 0.20 'C' 0.20 1.20 0 'Land use:permanen t grassland' 'History: grassland with grazing and application of 300-400 kg.ha-l.yr-1 N fromminera l fertilizer'

43 ANNEX 2 Example of a file with water retention characteristics (1stpage )

File: NLRU037.WRC Code: ASCII Access: sequential Author:E.J .Janse n Version:2 Date: 23-07-1991 Source: laboratory measurements, Fonck (ICW) Drying pF-curve;Ruurlo ,Th eNetherlands , field3 7 NULA UPDP LODP BD PFDE PFWE NUOB PF MOFR **********************************************************************

7 0.05 0.10 1.26 1 0 10 0.0 0.495 0.5 0.489 1.0 0.470 1.5 0. 434 1.8 0.388 2.0 0.350 2.3 0.290 2.7 0.237 3.4 0.185 4.2 0. 161 0.125 0.175 1.44 1 0 10 0.0 0.425 0.5 0.421 1.0 0.418 1.5 0.390 1.8 0.326 2.0 0.276 2.3 0.220 2.7 0.181 3.4 0.150 4.2 0.128 0.25 0.30 1.63 1 0 10 0.0 0.348 0.5 0.347 1.0 0.346 1.5 0.254 1.8 0.149 2.0 0.102 2.3 0.068 2.7 0:049 3.4 0.069 4.2 0.024 0.375 0.425 1.70 1 0 10 0.0 0.331 0.5 0.328 1.0 0.331 1.5 0.305 1.8 0.248 2.0 0.193 2.3 0.149 2.7 0.121 3.4 0.112 4.2 0.079 0.50 0.55 1.69 1 0 10 0.0 0.335 0.5 0.330 1.0 0.338 1.5 0.324 1.8 0.279 2.0 0.231 etc.

45 ANNEX 3 File with hydraulic conductivity data (1stpage )

File: NLRU000.HCU Code: ASCII Access:sequentia l Author:E.J .Janse n Version:3 Date: 23-07-1991 Source: Staringsoi l series (Wöstene tal. ,1987 ) 0-40 cm-soilsurface :topsoi lB 3 >40 cm-soilsurface :subsoi l0 2 NULA ÜPDP LODP NUOB HYCO MOFR **********************************************************************

2 0.00 0.40 45 0.178E+00 0.449 0.893E-01 0.44 0.438E-01 0.43 0.247E-01 0.42 0.140E-01 0.41 0.890E-02 0.40 0.655E-02 0.39 0.519E-02 0.38 0.412E-02 0.37 0.331E-02 0.36 0.269E-02 0.35 0.222E-02 0.34 0.184E-02 0.33 0.152E-02 0.32 0.125E-02 0.31 0.102E-02 0.30 0.083E-02 0.29 0.066E-02 0.28 0.051E-02 0.27 0.038E-02 0.26 0.028E-02 0.25 0.019E-02 0.24 0.013E-02 0.23 0.863E-04 0.22 0.562E-04 0.21 0.370E-04 0.20 0.250E-04 0.19 0.171E-04 0.18 0.119E-04' 0.17 0.848E-05 0.16 0.608E-05 0.15 0.427E-05 0.14 0.293E-05 0.13 0.197E-05 0.12 0.129E-05 0.11 0.809E-06 0.10 0.503E-06 0.09 0.301E-06 0.08 0.157E-06 0.07 0.593E-07 0.06 0.186E-07 0.05 0.497E-08 0.04 0.117E-08 0.03 0.249E-09 0.02 0.488E-10 0.01 0.40 1.20 39 0.639E+00 0.381 0.604E+00 0.38 0.351E+00 0.37 etc.

47 ANNEX 4 File with soil chemical data and particle size distribution

File: NLRU000.SCP Code: ASCII Access: sequential Author:E.J .Janse n Version:2 Date: 23-07-1991 Source: soil chemical data: Snijderse tal . (1987) particle size distribution: Jansen (1991) Ruurlo,Th eNetherlands , averagefo rth eentir e field

NULA UPDP LODP FROC FRNT PH FRCL FRSI FRSA

**********************************************************************

5 0.00 0.05 6.44 0.43 5.7 5.4 26.9 67.7 0.05 0.25 3.02 0.23 5.5 4.9 27.6 67.5 0.25 0.50 1.03 0.03 5.5 3.8 19.4 76.8 0.50 0.75 1.08 0.02 6.0 6.3 8.2 85.5 0.75 1.00 0.63 0.01 6.6 3.2 9.2 87.6

49 50 ANNEX 5 File with meteorological data (1stpage )

File: NLRU000.CLI Code: ASCII Access: sequential Author: E.J. Jansen Version: 2 Date: 23-07-1991 Source: precipitation: experimental field, temperature: Meteorological Station Almen radiation: Meteorological Station Haren

Meteorological data from 1-1-1980 to 31-5-1985 Missing values: MITE, MATE, AVWS and AVHM

YR MH DA DANU MITE MATE AVTE PR GLRA AVWS AVHM ********************************************************************** 1980 1 1 1 99. 99. 0.9 2.4 333. -1. -1 1980 1 2 2 99. 99. -0.4 2.3 127. -1. -1 1980 1 3 3 99. 99. 2.3 0.4 319. -1. -1 1980 1 4 4 99. 99. 1.6 2.2 63. -1. -1 1980 1 5 5 99. 99. 3.9 6.3 94. -1. -1 1980 1 6 6 99. 99. 5.0 4.4 110. -1. -1 1980 1 7 7 99. 99. 3.2 8.7 50. -1. -1 1980 1 8 8 99. 99. 1.4 0.0 177. -1. -1 1980 1 9 9 99. 99. 0.1 0.0 66. -1. -1 1980 1 10 10 99. 99. -0.5 0.0 246. -1. -1 1980 1 11 11 99. 99. -2.7 0.0 179. -1. -1 1980 1 12 12 99. 99. -5.5 0.0 417. -1. -1 1980 1 13 13 99. 99. -7.0 0.0 438. -1. -1 1980 1 14 14 99. 99. -6.1 0.0 158. -1. -1 1980 1 15 15 99. 99. -4.1 0.0 99. -1. -1 1980 1 16 16 99. 99. -2.1 0.0 183. -1. -1 1980 1 17 17 99. 99. -3.5 0.0 528. -1. -1 1980 1 18 18 99. 99. -4.5 0.0 121. -1. -1 1980 1 19 19 99. 99. -2.5 0.0 231. -1. -1 1980 1 20 20 99. 99. -0.9 0.0 238. -1. -1 1980 1 21 21 99. 99. 2.5 0.0 303. -1. -1 1980 1 22 22 99. 99. 4.3 4.3 127. -1. -1 1980 1 23 23 99. 99. 3.1 2.0 124. -1. -1 1980 1 24 24 99. 99. 2.1 0.6 102. -1. -1 1980 1 25 25 99. 99. 2.6 0.0 120. -1. -1 1980 1 26 26 99. 99. 0.9 0.5 344. -1. -1 1980 1 27 27 99. 99. 1.8 1.4 564. -1. -1 1980 1 28 28 99. 99. -0.6 0.0 111. -1. -1 1980 1 29 29 99. 99. 1.2 4.7 88. -1. -1 1980 1 30 30 99. 99. 6.2 0.9 191. -1. -1 1980 1 31 31 99. 99. 7.0 4.6 186. -1. -1 1980 2 1 32 99. 99. 1.3 11.4 483. -1. -1 1980 2 2 33 99. 99. 5.5 1.7 83. -1. -1 1980 2 3 34 99. 99. 4.0 9.3 206. -1. -1 1980 2 4 35 99. 99. 1.6 11.1 236. -1. -1 1980 2 5 36 99. 99. 7.8 8.0 103. -1. -1 1980 2 6 37 99. 99. 7.0 11.5 77. -1. -1 1980 2 7 38 99. 99. 6.3 0.8 129. -1. -1 1980 2 8 39 99. 99. 7.5 0.4 112. -1. -1 1980 2 9 40 99. 99. 8.5 0.0 349. -1. -1 1980 2 10 41 99. 99. 7.0 0.0 205. -1. -1 1980 2 11 42 99. 99. 5.6 0.0 303. -1. -1 1980 2 12 43 99. 99. 4.5 3.2 161. -1. -1 1980 2 13 44 99. 99. 5.0 1.3 294. -1. -1 1980 2 14 45 99. 99. 1.6 1.4 302. -1. -1 1980 2 15 46 99. 99. 5.1 0.0 195. -1. -1 1980 2 16 47 99. 99. 6.2 1.7 155. -1. -1 1980 2 17 48 99. 99. 5.6 0.0 246. -1. -1 1980 2 18 49 99. 99. 5.0 0.0 605. -1. -1 etc.

51 ANNEX 6 File with évapotranspiration data (1stpage )

File: NLRU000.ETR Code: ASCII Access: sequential Author: E.J. Jansen Version: 1 Date: 08-03-1989 Source: Meteorological Station Winterswijk, Penman open water evaporation (mm.decade-1) YR MH DA DANU ET **********************************************************************

1980 1 10 10 0 1980 1 20 20 1 1980 1 31 31 2 1980 2 10 41 4 1980 2 20 51 3 1980 2 29 60 5 1980 3 10 70 6 1980 3 20 80 8 1980 3 31 91 12 1980 4 10 101 18 1980 4 20 111 24 1980 4 30 121 25 1980 5 10 131 33 1980 5 20 141 44 1980 5 31 152 30 1980 6 10 162 28 1980 6 20 172 30 1980 6 30 182 25 1980 7 10 192 20 1980 7 20 202 18 1980 7 31 213 34 1980 8 10 223 31 1980 8 20 233 23 1980 8 31 244 22 1980 9 10 254 19 1980 9 20 264 17 1980 9 30 274 9 1980 10 10 284 8 1980 10 20 294 7 1980 10 31 305 3 1980 11 10 315 2 1980 11 20 325 4 1980 11 30 335 2 1980 12 10 345 0 1980 12 20 355 1 1980 12 31 366 2 1981 1 10 376 1 1981 1 20 386 0 1981 1 31 397 0 1981 2 10 407 4 1981 2 20 417 3 1981 2 28 425 5 1981 3 10 435 9 1981 3 20 445 12 1981 3 31 456 24 1981 4 10 466 21 1981 4 20 476 34 1981 4 30 486 22 1981 5 10 496 32 1981 5 20 506 41 1981 5 31 517 38 1981 6 10 527 42 1981 6 20 537 29 1981 6 30 547 23 etc.

53 54 ANNEX 7 Example of a file with soil moisture content data (1stpage )

File: NLRU037.SMO Code: ASCII Access: sequential Author: E.J. Jansen Version:2 Date: 16-10-1990 Source: gamma-radiation measurements Fonck (ICW) Soil moisture contents Ruurlo,Th eNetherlands , fieldnr . 37 daynumbers starta t1-1-198 0

YR MH DA DANU NÜLA UPDP LODP MOFR

**********************************************************************

1980 24 115 12 0.05 0, .15 0.347 0.15 0. .25 0.340 0.25 0. .35 0.224 0.35 0, .45 0.170 0.45 0, .55 0.197 0.55 0, .65 0.266 0.65 0. .75 0.295 0.75 0. .85 0.337 0.85 0. .95 0.341 0.95 1. .05 0.361 1.0 5 1. .15 0.362 1.1 5 1. .25 0.337 1980 21 142 12 0.05 0, .15 0.244 0.15 0, .25 0.197 0.25 0, .35 0.153 0.35 0, .45 0.201 0.45 0, .55 0.189 0.55 0. .65 0.244 0.65 0, .75 0.270 0.75 0. .85 0.317 0.85 0, .95 0.332 0.95 1. .05 0.346 1.05 1. .15 0.356 1.15 1. .25 0.344 1980 28 149 12 0.05 0, .15 0.221 0.15 0. .25 0.185 0.25 0 .35 0.135 0.35 0 .45 0.130 0.45 0. .55 0.184 0.55 0 .65 0.232 0.65 0. .75 0.290 0.75 0. .85 0.320 0.85 0. .95 0.341 0.95 1. .05 0.350 1..0 5 1. .15 0.356 1..1 5 1 .25 0.336 1980 6 158 12 0.05 0 .15 0.203 0.15 0 .25 0.166 0.25 0. .35 0.126 0.35 0. .45 0.124 0.45 0. .55 0.185 0.55 0. .65 0.243 0.65 0. .75 0.293 0.75 0 .85 0.325 0.85 0. .95 0.334 0.95 1 .05 0.347 1.05 1 .15 0.356 etc.

55 ANNEX 8 File with soil temperature data (1stpage )

File: NLRU000.STE Code: ASCII Access: sequential Author: E.J. Jansen Version: 1 Date: 22-12-1988 Source: measurements CABO, Wageningen Average soil temperature (oC)a t three depths Ruurlo, The Netherlands daynumbers start at 1-1-1980

NUDP DP(1,2...NUDP YR MH DA DANU SOTE(1 ) SOTE(2) SOTE(3 )

********************************************************************** 3 0.05 0.1 5 0.30 1980 4 2 93 7.7 7.1 7.0 1980 4 15 106 8.3 8.3 8.7 1980 4 23 114 6.6 6.8 7.6 1980 5 1 122 9.1 8.8 8.9 1980 5 8 129 9.8 9.4 9.4 1980 5 16 137 10.6 10.5 10.9 1980 5 22 143 11.8 12.2 12.5 1980 5 27 148 13.0 11.9 11.8 1980 6 5 157 18.7 14.9 13.3 1980 6 12 164 19.8 16.1 14.7 1980 6 19 171 13.8 13.8 14.3 1980 6 25 177 14.9 14.1 13.7 1980 7 3 185 16.5 14.8 14.3 1980 7 10 192 16.1 15.5 15.3 1980 7 17 199 15.6 14.3 14.1 1980 7 25 207 16.1 15.5 15.0 1980 8 1 214 19.8 17.8 17.6 1980 8 8 221 20.5 18.6 17.7 1980 8 15 228 17.5 17.0 16.9 1980 8 22 235 16.7 16.4 16.5 1980 8 30 243 17.8 17.0 16.8 1980 9 8 252 17.2 15.7 15.8 1980 9 12 256 15.5 15.1 15.2 1980 9 22 266 17.9 16.6 16.4 1980 10 3 277 11.9 12.9 13.6 1980 10 10 284 10.4 10.5 11.5 1980 10 18 292 10.9 10.6 11.0 1981 1 27 393 3.1 2.5 2.8 1981 2 11 408 2.1 3.1 4.0 1981 2 21 418 0.2 0.7 1.5 1981 3 6 431 0.4 2.5 5.4 1981 3 17 442 6.1 5.7 6.2 1981 3 31 456 8.5 6.6 5.3 1981 4 10 466 10.0 9.0 9.4 1981 4 21 477 7.5 7.6 8.4 1981 4 27 483 8.0 8.1 8.6 1981 5 8 494 13.9 11.4 10.0 1981 5 18 504 16.2 13.6 12.4 1981 5 29 515 15.2 13.5 13.3 1981 6 9 526 17.6 16.4 15.8 1981 6 16 533 15.7 15.3 15.4 1981 6 24 541 22.6 17.8 16.1 1981 7 3 550 17.2 16.4 15.7 1981 7 7 554 21.7 18.4 16.6 1981 7 16 563 18.7 17.5 17.0 1981 7 24 571 16.6 16.5 16.9 1981 7 31 578 16.2 15.3 15.9 1981 8 11 589 18.6 17.8 18.0 1981 8 22 600 16.4 15.4 15.9 etc.

57 ANNEX 9 Example of a file with groundwater level data (1stpage )

File: NLRU037.GWL Code: ASCII Access: sequential Author:E.J .Janse n Version:2 Date: 31-07-1990 Source: piezometer measurements Fonck (ICW) groundwater levels Ruurlo,Th eNetherlands , field nr.3 7 daynumbers starta t1-1—198 0

YR MH DA DANU GWLV *********************************************************************

1980 4 24 115 0.71 1980 5 2 123 1.04 1980 5 7 128 0.81 1980 5 21 142 1.04 1980 5 28 149 1.14 1980 6 6 158 1.18 1980 6 11 163 1.24 1980 6 27 179 1.19 1980 7 9 191 0.82 1980 7 25 207 0.46 1980 8 8 221 0.85 1980 8 20 233 0.87 1980 9 4 248 0.85 1980 9 19 263 0.68 1980 10 3 277 0.91 1980 10 14 288 0.81 1980 10 28 302 0.70 1981 1 24 390 0.17 1981 3 3 428 0.52 1981 3 24 449 0.43 1981 4 7 463 0.64 1981 4 13 469 0.73 1981 4 21 477 0.80 1981 4 27 483 0.85 1981 5 7 493 0.70 1981 5 13 499 0.9 2 1981 5 19 505 0.93 1981 5 26 512 0.95 1981 6 2 519 0.86 1981 1981 6 9 526 0.89 1981 6 12 529 0.97 1981 6 16 533 1.03 1981 6 24 541 1.11 1981 6 30 547 0.52 1981 7 7 554 0.77 1981 7 9 556 0.85 1981 7 15 562 0.72 1981 7 21 568 0.83 1981 7 28 575 0.56 1981 8 4 582 0.79 1981 8 11 589 0.91 1981 8 18 596 1.08 1981 8 25 603 1.14 1981 8 31 609 1.21 1981 9 1 610 1.21 1981 9 3 612 1.25 1981 9 8 617 1.30 1981 9 15 624 1.30 1981 9 22 631 1.17 1981 9 30 639 1.18 etc. 10 7 646 1.12

59 ANNEX 10 Example of a file with management data (1stpage )

File: NLRU039.MAN Code: ASCII Access: sequential Author: E.J. Jansen Version: 2 Date: 03-08-1989 Source: Snijders et al. (1987) Ruurlo, The Netherlands, field nr.3 9 daynumbers start at 1-1-1980 YR MH DA DANÜ AC NUAN MTTY DP AMMT AMDM AMOM AMNT AMNH AMNI AMPT AMK AMCA AMMG ***************************************************************** Management data

1980 3 18 78 10 1 0.20 42000 4368 3276 201.6 80.6 0.0 36.7 223.3 87.2 35.6 1980 3 24 84 10 6 0.00 -1 -1 0 100.0 50.0 50.0 36.9 119.5 0.0 27.7 1980 5 7 128 10 6 0.00 -1 -1 0 80.0 40.0 40.0 0.0 0.0 0.0 21.7 1980 5 29 150 10 6 0.00 -1 -1 0 80.0 40.0 40.0 0.0 0.0 0.0 0.0 1980 6 25 177 10 6 0.00 -1 -1 0 60.0 30.0 30.0 30.6 99.6 0.0 0.0 1980 7 29 211 10 6 0.00 -1 -1 0 40.0 20.0 20.0 0.0 0.0 0.0 0.0 1980 8 19 232 10 6 0.00 -1 -1 0 40.0 20.0 20.0 24.5 79.7 0.0 0.0 1980 9 17 261 10 6 0.00 -1 -1 0 40.0 20.0 20.0 0.0 46.5 0.0 0.0 1981 3 24 449 10 6 0.00 -1 -1 0 0.0 0.0 0.0 34.9 83.0 0.0 30.1 1981 4 15 471 10 1 0.20 41460 4560 3524 207.3 82.9 0.0 28.9 220.3 65.2 32.5 1981 4 16 472 10 6 0.00 -1 -1 0 100.0 50.0 50.0 0.0 0.0 0.0 27.4 1981 5 22 508 10 6 0.00 -1 -1 0 80.0 40.0 40.0 0.0 83.0 0.0 21.9 1981 6 19 536 10 6 0.00 -1 -1 0 80.0 40.0 40.0 0.0 66.4 0.0 0.0 1981 7 14 561 10 6 0.00 -1 -1 0 60.0 30.0 30.0 0.0 66.4 0.0 0.0 1981 8 5 583 10 6 0.00 -1 -1 0 40.0 20.0 20.0 0.0 66.4 0.0 0.0 1981 9 8 617 10 6 0.00 -1 -1 0 40.0 20.0 20.0 0.0 66.4 0.0 0.0 etc.

61 ANNEX 11 Example of a file with crop data (1st page)

File: NLRU037.CRP Code: ASCII Access: sequential Author: E.J. Jansen Version: 1 Date: 26-01-1989 Source: Snijders et al. (1991) Data on crop sowing and harvest dates,yield s and residues Ruurlo, The Netherlands, field nr.3 7 daynumbers start at 1-1-1980

YR MH DA DANÜ CRTY AC CRYD CRNT CRNTYD RSYD RSNT RSNTYD

1980 5 6 127 1 3 3635 0.0301 127.6 0 0 0 1980 5 28 149 1 3 1880 0.0390 73.3 0 0 0 1980 6 24 176 1 3 2445 0.0425 103.9 0 0 0 1980 7 24 206 1 3 2562 0.0334 85.6 0 0 0 1980 8 19 232 1 3 2017 0.0422 85.1 0 0 0 1980 9 17 261 1 3 2121 0.0412 87.4 0 0 0 1980 10 23 297 1 3 1655 0.0421 69.9 0 0 0 1981 4 14 470 1 3 659 0.0286 18.9 0 0 0 1981 5 19 505 1 3 2804 0.0421 118.0 0 0 0 1981 6 16 533 1 3 2807 0.0418 117.3 0 0 0 1981 7 14 561 1 3 1625 0.0457 74.3 0 0 0 1981 8 5 583 1 3 3084 0.0267 82.3 0 0 0 1981 9 8 617 1 3 2448 0.0373 91.3 0 0 0 1981 10 28 667 1 3 2331 0.0335 78.1 0 0 0 1982 3 22 812 1 1 0 0.0000 0.0 0 0 0 1982 5 11 862 1 3 1500 0.0476 71.4 0 0 0 1982 6 1 883 1 3 3645 0.0408 148.7 0 0 0 etc.

63 ANNEX 12 Example of a file with soil mineral nitrogen data (1stpage )

File: NLRU037.SMN Code: ASCII Access: sequential Author: E.J. Jansen Version: 1 Date: 25-01-1989 Source: Measurements IB Haren. Soil mineral N; Ruurlo, The Netherlands, field nr.3 7 daynumbers start at 1-1-1980

YR MH DA DANU NULA UPDP LODP BD AMNH AMNI *********************************************************************

1980 3 12 72 5 0.00 0.05 1.15 4.0 8. 1 0.05 0.25 1.44 2.9 8. 6 0.25 0.50 1.59 4.0 4. 0 0.50 0.75 1.54 0.0 11. 6 0.75 1.0 0 1.60 0.0 16. 0 1980 4 18 109 5 0.00 0.05 1.15 12.1 14.. 9 0.05 0.25 1.44 2.9 37. 4 0.25 0.50 1.59 0.0 11., 9 0.50 0.75 1.54 0.0 7.. 7 0.75 1.00 1.6 0 0.0 8., 0 1980 5 9 130 4 0.00 0.05 1.15 46.0 64., 4 0.05 0.25 1.44 17.3 25., 9 0.25 0.50 1.59 4.0 8., 0 0.50 1.00 1.57 0.0 23., 6 1980 6 4 156 4 0.00 0.05 1.15 32.2 75. 9 0.05 0.25 1.44 11.5 60.. 5 0.25 0.50 1.59 4.0 15.. 9 0.50 1.00 1.57 0.0 23.. 6 1980 6 26 178 4 0.00 0.05 1.15 97.2 40.. 3 0.05 0.25 1.44 17.3 80., 6 0.25 0.50 1.59 0.0 11., 9 0.50 1.00 1.57 39.3 78., 5 1980 7 25 207 4 0.00 0.05 1.15 12.6 14., 9 0.05 0.25 1.44 5.8 23.. 0 0.25 0.50 1.59 0.0 67., 6 0.50 1.00 1.57 0.0 55.. 0 1980 8 19 232 4 0.00 0.05 1.15 17.3 10,. 3 0.05 0.25 1.44 14.4 23.. 0 0.25 0.50 1.59 4.0 19 .9 0.50 1.00 1.57 0.0 23 .6 1980 9 17 261 4 0.00 0.05 1.15 15.5 2 .9 0.05 0.25 1.44 5.8 40 .3 0.25 0.50 1.59 0.0 43 .7 0.50 1.00 1.57 0.0 47 .1 1980 11 20 325 5 0.00 0.05 1.15 8.1 6 .9 0.05 0.25 1.44 2.9 17 .3 0.25 0.50 1.59 0.0 47 .7 0.50 0.75 1.54 0.0 42 .4 0.75 1.00 1.6 0 0.0 36 .0 1981 4 6 46 2 5 0.00 0.05 1.15 7.5 6 .9 0.05 0.25 1.44 0.0 8 .6 etc.