摘要：Within the German "Research Alliance on Agroecosystems Munich" (Forschungsverbund Agrarökosysteme München, FAM) optimal land use strategies are investigated since 1990 in terms of minimization of environmental impacts and maximization of profit from agricultural lands (Auerswald et al. 2000). For this purpose a conventional agricultural land use system was converted into two more sustainable forms of land use. One part of the farm was converted into an integrated land use system with reduced tillage, direct seeding methods and catch crops to minimize nutrient losses and to prevent soil erosion hazards. The other part of the farm was converted into a biological land use system with the omission of mineral fertilizers and pesticides and the enrichment of crop rotation. In order to evaluate changes in the state of the agroecosystem a goal and indicator system was elaborated which was aimed to represent important issues of sustainable agriculture. With the help of the goal and indicator system the impact of land use on issues of sustainability can be assessed. The indicators are furthermore integrated into a farm model to assess the implications of the realization of environmental issues in agriculture. For this purpose the model system MODAM (Zander & Kächele 1999) was used to compare different land use options at the farm level. The model system simulates agricultural land use, calculates the economic returns and runs farm optimizations with a linear programming tool. The integration of agro-environmental indicators in the model framework enables a multiple goal optimization and the calculation of trade-offs. For this study soil erosion was assessed with the algorithms of a site-specifically adapted version of the USLE (ABAG, Schwertmann et al. 1987). Optimization runs show, that e.g. soil conservation measures may not only improve soil conservation, but also the economic situation. A slight improvement of soil conservation results in marginal opportunity costs for the farm. With the realization of a higher level of soil protection opportunity costs rise exponentially. The calculated opportunity costs can give valuable hints on bottlenecks of the realization of sustainable agriculture and help to identify reasonable incentives for a better agriculture. Furthermore conflicts between divagating goals can be identified to find optimal pathways of a sustainable development of agriculture.
