Recent findings concerning nitrogen cycling and dynamics are discussed. Ruminants excrete most of the N intake in urine, from which it is easily lost. By proper management of liquid manure in the case of loose housing, losses can be reduced to about 10% of excreted nitrogen. The same reduction can be reached in stanchion stables with straw. Deep litter systems result in greater losses. Catch crops are able to take about 2 kg N day−1and after incorporation the release of nitrogen starts almost immediately. The mineralisation of nitrogen can be estimated for each addition of organic matter. The weather pattern and the timing of soil tillage have a strong influence on the speed of mineralisation. Physical and morphological properties of soil influence the leaching of nitrogen. By-pass flow may reduce leaching from the sub-soil and speed it up from the top soil. The nitrogen fixation capacity of grass clover mixtures is high and allows severe losses without affecting the production level of the farm. Management supporting models can be used to generate ideas about the nitrogen management of arable land. The management of the nitrogen in grassland is often complicated due to temporary lability of the composition of grass/clover mixtures. Losses by leaching can be reduced by making silage in autumn and by balancing the feed.