The AGRUM model network as an instrument for countrywide nutrient management in Lower Saxony.
Since 2000 the Water Framework Directive defines water quality targets for groundwater, surface water bodies and coastal waters in the European Union. Employing the model network AGRUM, consisting of the agricultural sector models RAUMIS, the model system GROWA, DENUZ/WEKU, MEPhos and the nutrient transfer model MONERIS, all relevant diffuse and point source nutrient inputs and loads have been simulated for the Federal State of Lower Saxony. The nutrient input situation in 2021 was modelled based on the reference year 2007. Thereby the Fertilizer Directive of 2006, the agri-environmental programs in the period of 2007 to 2013, the future development of the agricultural markets and of agricultural policy have been taken into account. The results predict that the measures and actions already implemented and adopted are not adequate for Lower Saxony to achieve the water quality targets of the Water Framework Directive state wide until 2021. Agri-environmental measures designed to reduce nitrogen balance surpluses on agricultural land and improve water quality, as complementary measures, show a high reduction potential. In other regions an extension of agri-environmental measures to the entire agricultural area of the region might be insufficient to achieve the quality targets. Especially in these regions an increase of the existing area of agri-environmental measures is not realistic due to high intensity agricultural production, a high income and the existing land use pressure. Therefore it is necessary to consider further options for action.