Simulation of growth, water and nitrogen uptake of a wheat crop using the SPASS model

The process modules developed and integrated in the simulation model SPASS (Soil–Plant–Atmosphere Systems Simulation) and the simulation results using these modules parameterized for winter wheat are presented in this paper. These modules have been developed based largely on the existing model theories and can be used generally to simulate the dynamic processes in different soil–plant–atmosphere systems. They are exchangeable and are programmed in the form of C functions and stored in a Dynamic Link Library (DLL). The simulation results for three winter wheat varieties in the Netherlands, North and South Germany show that the parameterised model can simulate biomass growth, water uptake, and nitrogen uptake of wheat crop reasonably well if no extreme conditions or damage (by pest and disease) occur. The soil water contents and the contents of mineral nitrogen were also predicted with acceptable accuracy. Further, the importance of component level modelling is demonstrated using the modular SPASS framework.