In Finland, pastures cover approximately 100 000 ha. Grazing is natural, cheap and the second most important feed of dairy cows in Finland. In intensive grazing 75-90 % of the N ingested by the cows is returned to the pasture in dung and urine and the nutrients are constantly recycling through soil, air, vegetation, grazing animal and excreta. Dung and urine patches are the hot spots of intensive N cycling on pastures and also the main sources for the N losses that are both an economical loss for farmer and a hazard to the environment. The aim of this study was to measure the main N processes and losses of the N cycle in boreal dairy pasture systems. The experiments were mostly conducted on lysimeter field at MTT Agrifood Research, Maaninka. Pasture N utilization is ineffective compared to silage cutting especially when high amounts of concentrates or protein supplementation is used. Transformations and immobilisation/ mineralization turnover of N are high due to short term ley conditions. When the management changes almost yearly, the soil N is in constant state of change and equilibrium is never achieved. Nitrogen is accumulated in soil during grass cover years and mineralized during the renewal year. Thus, N fertilization for newly sown sward and cover crop after pasture renewal is not needed. In winter microbial activity in soil slows down, but still continues even in temperatures below zero. Freezing prevents most water movement in soil and nitrate therefore accumulates. Nitrogen discharges in spring through leaching and gaseous losses when soil thaws and snow cover melts. Leaching of N is largest after pasture renewal. Nitrogen loss in surface runoff is small and not important during the whole ley period. A white clover mixture decreases N leaching losses at pasture and offers more efficient N utilization compared to a 220 kg N ha-1 y-1 fertilized grass sward. The importance of pastures as a source of NH3 emission in Finland is minor and has been overestimated previously. Nitrous oxide emissions from pastures were also smaller than estimated in the IPCC report. The watering facility area functions as a cattle congregation area. Thus it receives a large amount of excretal N and suffers treading damage that destroys the vegetation and soil pore structure causing N leaching losses, surface runoff and gaseous emissions. Based on these results, it is essential to include the whole ley rotation in short-term ley studies because of the cumulative effect of N inputs in previous years and the N mineralization pulse after cultivation of the soil, which greatly increases N losses.