Agroscope, 8046 Zurich, Switzerland

Economic and ecological assessment of scenarios for nutrient reduction in water bodies

Four different scenarios for the reduction of diffuse nutrient inputs from agriculture to water bodies in Switzerland were analysed for the period 2010 to 2025 in a multidisciplinary project. The agricultural sector model SWISSland was used to examine the economic and structural effects, and the influence on the direct payments budget and sectoral income, following implementation of emission mitigation measures. The substance flow model MODIFFUS was employed to estimate the diffuse nitrogen and phosphorus inputs from agriculture into bodies of water. The agricultural life cycle assessment method SALCA was used to determine the environmental effects, including those of imported products. All four scenarios lead to extensification in arable farming and forage crop production. Depending on the scenario, nitrogen inputs from farmland are projected to decline by 5 – 25 % from 2010 to 2025, and phosphorus losses by 7 – 20 %. Domestic production would decrease for many products and import volumes would rise. The reduction in nutrient inputs into water bodies in Switzerland would therefore lead to a shifting of environmental impact to other countries.

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