Intensified agriculture is often associated with nitrous oxide (N2O) emissions and nitrate (NO3) leaching losses into groundwater due to high application rates of N-fertilizer, increasing maize cultivation and ploughing up permanent grassland. N2O is an important anthropogenic greenhouse gas and agriculture is one of the main polluters. NO3 leaching endangers groundwater quality. In a field experiment on the organically managed farm “Lindhof” in Northern Germany three different forage production systems (1. crop rotation, 2. continuous silage maize 3. permanent grassland) were established parallelly after a) ploughing up permanent grassland and b) longtime arable use. N2O emissions were measured weekly over the two-year experimental period. Soil water samples were taken over the leaching season (Oct-Mar) once a week and analysed for N-content. The production systems “crop rotation” and “continuous maize” showed significant higher amounts of N2O emissions and NO3 leaching than the newly established or resown grassland. In the system “crop rotation”, maize after grass-clover had the highest emissions, because of high N-mineralization of clover residues, both during and after growing season. Long-term cropping history and manure application had no significant effects, but on plots established on former grassland, emissions and leaching tended to be higher
