Assessment Of Agricultural Nitrogen Balances For Municipalities - Example Baden-Wuerttemberg (Germany)

For the implementation of the Water Framework Directive (WFD) the spatially differentiated evaluation of water eutrophication caused by non-point source nitrogen input constitutes a central issue. The nitrogen (N) balance surplus is a commonly used indicator for identifying areas vulnerable to nutrient pollution. The WFD recommends a minimum area of ca. 10 km(2) for the spatial resolution of river basin management plans, thus it is also appropriate to calculate the nitrogen balances with a comparable spatial resolution. In Germany municipalities (EU nomenclature: LAU level 2) are the smallest administrative units for which Agricultural Census data are available. However, it is necessary to replace numerous entities in the Agricultural Census records that were not published for reasons of data secrecy. The estimation of nitrogen mineral fertilizing quantities for regional units is considered to be the most critical point of a N balance. Using nitrogen surface balance calculations for the municipalities of the federal state of Baden-Wuerttemberg (Germany), approaches will be introduced for both points which lead to reasonable results.