Impact of nitrogen reduction measures on the nitrogen loads of the river Ems and Rhine (Germany)

This paper focuses on the analysis of the effects of certain policy measures to reduce diffuse pollution by nitrogen. For this purpose, a model system consisting of an agricultural sector model, a water balance model and a residence time/denitrification model was combined and applied. First results indicate a wide range of annual nitrogen surpluses for the rural areas between less than 10 N ha−1 a−1 up 200 kg N ha−1 a−1, or more depending on the type and intensity of farming. Compared to the level of nitrogen surpluses the level of nitrogen inputs into the surface waters is relatively moderate because of degradation processes during transport in soil and groundwater. Policy impact analyses for a nitrogen tax and a limitation of the livestock density stress the importance of regionally adjusted measures.