1. E. Priesack and S. Gayler Workshop Halle 18.-20.Sept. 2005 Modelling Soil-Plant-Atmosphere Interactions of the long-term experiment Bad Lauchstädt

2. Originally Expert-N is an agro- ecosystem model which can be applied to consult farmers to optimize (N-) fertilization predict crop growth understand dynamics of agro- ecosystems avoid groundwater pollution by nitrate reduce nitrous oxide emissions

3. Rooted Zone Groundwater Unsaturated Zone leaching Lateral Flow Water Balance Precipitation Infiltration Evaporation Interception Run off Transpiration Root Water Uptake capillary rise

4. root zone groundwater unsaturated zone N-fixation organic fertiliser mineral fertiliser nitrification NH 4 +  NO 2 -  NO 3 - organic N mineralisation immobilisation N removed by harvesting NH 3 N2N2 N2ON2ONO x volatilisation denitrification NO 3 - - leaching lateral transport Nitrogen Balance N-deposition

5. Model application needs input data about basic soil parameters climatic and weather conditions land use management

6. Expert-N Datamanagement ASCII interface Expert-N Simulator system control process calculation graphical output ASCII output ASCII interface SQL interface ASCII interface External geographic data GIS ArcView SQL interface Manual data input Expert-N Database Simulation-Objects / MSWD-Library ASCII interface External data storage

8. Litter Manure Humus ManureSurf manure roots LitterSurf residues mineralisation added organic matter Soil Organic Matter Pools Mineralisation Module according to the model SOILN (Johnsson et al. 1987)

9. Wetter Bad Lauchstaedt (1902 – 2002)

10. Bodenhorizonte Profil 1

11. Pflanzendaten

12. Mineraldüngung

13. Organische Düngung

14. Bodenbearbeitung

15. Simulationsobjekte

16. Expert-N Model Configuration

17. Mineralisation Model Calibration

18. vegetative biomass above ground storage organs Expert-N Plant Simulation

19. Observed and simulated rTOC values as function of time

20. Mineralisation Model Parametrisation

21. Long-term Simulation (1906-2002): Yield

22. Long-term Simulation (1906-2002): relative TOC

23. Results are only very preliminary: Plant growth (potato!) and C- and N cycling needs further calibration Steps IIb and IIc were not considered Conclusions