Johannes Deelstra

Agricultural University, Wageningen, The Netherlands

Jordforsk

Modelling in monitored catchments

Experiences from case studies in Norway

SOIL/SOILN_NO in the Skuterud catchment

SOILNDB in the Mørdre catchment

Location of catchments in the JOVÅ-programme

North pole

EU, y/n

president Bush

Volvo

The Skuterud catchment

Land use Area ( ha)Agricultural area 272forest area 129Bogs 10roads, farms 13Housing area 25Total area 449

In operation since 1993

The Mørdre catchment

Land use Area (ha) Agricultural area 444Forest 192Bogs 27Housing area, roads, etc 18Sum 681

In operation since 1991

Measurement programme in JOVÅ-catchments

Discharge measurement

Water sampling and analysis(TDS, Ntot, Ptot)

runoff(mm)

N,P,SS loss (ha-1)

Collection of information on farming practices

type of crop fertiliser application yield sowing/harvesting dates type/date of soil tillage

Measurement programme in JOVÅ-catchments (cont’d)

In additionsoil mapping, profile descriptionsadditional determinations of soil physical parameters

Simulation Skuterud

water and heat transport in the vertical profile daily meteorological data and soil physical parameters, initial

values numerous switches to set

The Soil model

SOILN_NO, Norwegian version of the Swedish SOILN model

- includes major nitrogen and carbon processes - many inputs from SOIL- nitrogen application including the dates of application, type of crops, sowing and harvesting dates, crop yield ploughing dates- MATLAB

NITROGEN LEACHING FROM THE ROOT-ZONE TO TILE DRAINAGE/GROUNDWATER.

Simulation for each farmer field

SimulationsNo measuresWith measures

Optimal fertiliser applicationCatch cropsIrrigation

Skuterud

Nitrogen runoffno measures

Period Measured Simulated Simulated/Measured April 94 - April 95 46 48.4 1.05 April 95 - April 96 22 22.9 1.04 April 96 - April 97 30 25.8 0.86 April 97 - April 98 40 30.8 0.77 Accumulated 1994-1998 138 128 0.93

Skuterud

Comparison of measures

0

2 0

4 0

6 0

8 0

1 0 0

1 2 0

1 4 0

Accu m u la te d Ap ril 9 4 - Ap ril

9 5

Ap ril 9 5 - Ap ril

9 6

Ap ril 9 6 - Ap ril

9 7

Ap ril 9 7 - Ap ril

9 8

Simu latio n pe riod

We

igh

ted

N-l

os

s,

kg

/ha

Init ial N-loss N-loss with reduced fert ilization

N-loss with catchc rop N-loss with irrigation

Skuterud

Effects(%)

Opt. fert. appl.: 4.7 , Catchcrops: 20, Irrigation: 12

Nitrogen leaching maps

Skuterud

Mørdre - SOILNDBLarsson et al. (2001), SLU

A ”shell” in Visual Basic, coupling SOIL og SOILN(SLU)

To quantify N-loss from agricultural areas

Input og parameterisering Input preperation: through Excel into SOILNDB-database

climatological data soilsdata farming practices (fert., soil prep., etc)

Parameter setting: through SOILNDB-database (possibility to change) through changing program-code

Soils soil physical parameters (pF, ksat, texture, org. matter)

two alternative sources: from soil database in SOILNDB (10 USDA jordarter og 7

”Nordic” soil types. own data

Farming practicescrop type,

fertiliser, type and quantity

soil tillage, type, date

Simulation procedure Mørdre

Simulation for individual farmer fields (input; farmer information)for 2 ha units(input SSB)

Results: runoff(mm)

0

100

200

300

400

500

600

700

1991-92 1992-93 1993-94 1994-95 1995-96 1996-97 1997-98 1998-99 1999-00

dato

av

ren

nin

g (

mm

)

Målt avrenning (mm)

Simulert avrenning (mm) med JOVÅ data

Simulert avrenning (mm) med SSB data

Results: nitrogen losses

0

10

20

30

40

50

60

70

80

1991-92 1992-93 1993-94 1994-95 1995-96 1996-97 1997-98 1998-99 1999-00

Målt nitrat-N tap (kg/ha)

Simulert nitrat-N tap (kg/ha) med SSB data

Simulert nitrat-N tap (kg/ha) med JOVÅ data

Summary both models; user friendly

SOIL/SOILN_NO/SOILNDB, one dimensional - catchment?

one dimensional model size of catchment(limits?) surface runoff?

validation of modelling results against total catchment runoff; justified? what about flow processes?

how to deal with variability in catchments soil physical parameters, sowing/harvesting, fertiliser application