Abstract This work presents an investigation into the use of nitrogen on 46 dairy farms in North-West Germany. The dairy farms included both conventional and organic dairy farms. With the help of nitrogen balances for the whole farm, the animal and the field compartment the efficiency of nitrogen in production systems is determined, and N-surpluses, N-flows within the system and N-losses are identified. The mean nitrogen surplus is 146 kg N ha-1and the efficiency at the whole farm level is an average of 26%. The factors which influence the N-surpluses are determined using factor analysis, the most important of which is the intensity of production. Options for improving nitrogen use are reviewed and their implementation and effectiveness on the working dairy farms are assessed.weiterlesen