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 useArea ( ha) Agricultural area 272 forest area 129 Bogs 10 roads, farms 13 Housing area 25 Total area 449 In operation since 1993

The Mørdre catchment Land use Area (ha) Agricultural area 444 Forest 192 Bogs 27 Housing area, roads, etc 18 Sum 681 In operation since 1991

Measurement programme in JOVÅ- catchments Discharge measurement Water sampling and analysis(TDS, N tot, P tot ) 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 addition soil mapping, profile descriptions additional 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 Simulations No measures With measures Optimal fertiliser application Catch crops Irrigation Skuterud

Nitrogen runoff no measures Skuterud

Optimal fertiliser application Skuterud Nitrogen loss with optimal fertiliser application

Catchcrops Skuterud Nitrogen loss when catchcrops

Irrigation Skuterud Nitrogen loss when irrigation

Comparison of measures Skuterud Effects(%) Opt. fert. appl.: 4.7,Catchcrops: 20, Irrigation: 12

Nitrogen leaching maps Skuterud

Mørdre - SOILNDB Larsson 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, k sat, texture, org. matter) two alternative sources:  from soil database in SOILNDB (10 USDA jordarter og 7 ”Nordic” soil types.  own data Farming practices crop 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)

Results: nitrogen losses

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