Studying Parameter Sensitivity and Behaviour of the Crop Model STICS

The present article shows the results of a study on the soil module of the STICS (Simulateur Multidisciplinaire des Cultures Standards, developed by INRA, France) crop model. Simulation models are often applied to regions where conditions are substantially different from the ones which the model was originally developed for and validated against. This was the reason to study the sensitivity of the STICS soil module and to analyze model behavior with regard to spatial transferability. The model was parameterized with data collected from an area close to the German city of Trier. Using this parameterization as a baseline, an initial study was carried out on the sensitivity of the soil parameters. This was followed by an analysis of model behavior concerning parameters which also in the real system are responsible for successful or poor plant growth. This provided some improvements over the initial simulation results. However, the model failed to match the real system's behavior concerning yield, biomass development, and root growth. From various approaches to parameterization it has become clear that a high level of abstraction is required to produce a satisfactory model of the soil-plant-atmosphere continuum and in particular the soil water dynamics. This applies especially to extreme locations as well as to relatively extreme climatic years.