Definition: Nitrogen surplus
Nitrogen surplus is the potential surplus of nitrogen on agricultural land, calculated as the difference between nitrogen inputs to an agricultural system and nitrogen removed from the system per hectare of agricultural land. The nitrogen inputs taken into account in this balance are mineral fertilisers and organic manure applied to agricultural land, fixation by leguminous crops and clover, and wet and dry deposition from the atmosphere. Nitrogen outputs are the nitrogen content in harvested arable crops and crops used for fodder.
Eurostat, "Measuring progress towards a more sustainable Europe. Sustainable development indicators for the European Union. Data 1990-2005", Office for Official Publications of the European Communities, Luxembourg, 2005