Applications of optimum control theory to agroecosystem modelling

This contribution proposes an application of ecological models in the framework of optimum control theory. A typical example of a simulation model, which describes processes of an agricultural ecosystem, is used to derive optimum management strategies: fertilising schemes and crop rotations. Several assessment scenarios of production schemes are compared with the tool of optimisation. In this context mathematical properties of ecological models are discussed. Ecological models are heterogeneous in mathematical structure and incorporate different characteristic time scales. The numerical algorithms of optimum control have to deal with these problems. The proposed simulation model for crop growth, nitrogen dynamics in soil and a pest population is based on data series from the collaborative research project 179 ‘water- and matter-dynamics in agroecosystems’. The model is applied to the environmental conditions of one investigation site of the project: the ‘Ohebach’ catchment in Lower Saxonia (‘Niedersachsen’), Germany.