Quantitative aspects of sustainable agriculture

Control theory provides methods to calculate optimal control of agricultural ecosystems based on dynamic models. Optimization problems formulated with these models can focus either on small time scales (one vegetation period) or significant larger scales (crop rotations). Performance criteria are developed which include sustainability in addition to economic criteria. An aggregated model simulates crop growth and soil nitrogen dynamics in an ecotope. An optimal control problem is defined with fertilizing as control variable and solved for several performance criteria. Optimization results show that both, acceptable yields and drastic reduction of environmental side effects can be achieved.