EN
The aim of researches was aimed at determining the influence of natural factors, altitude, slope and climatic conditions on yield - producing effect of nitrogen of mountain grassland. The research was carried out in four field experiments in the years 1987-90 in representative conditions for the Sudety Mountains, as regards above - mentioned factors. Two experiments were set up in the 400 - 500 m a.s.l., two next 600-700 m a.s.l. In each zone, one of the experiments was in flat area, the other one on the slope. Simulated grazing utilization was used, and the following fertilization rates: 100 kg/ha P₂O₅ and 60 kg/ha K₂O in spring and three nitrogen levels: 100,150 and 200 kg/ha were applied. Mean annual yields in the research period were: 4,91 t/ha DM in the lower zone and 4,57 t/ha DM in the higher zone. 200 m difference in altitude caused decrease of yields, on the average 0,34 t/ha. Slope affected yields more substantially. In the lower zone difference in favour of flat area was 1,36 t/ha DM, whereas in the higher zone yields were higher by 0,54 t/ha DM on the slope. Increasing level of nitrogen input gave significantly higher yields on the lower zone site and in the flat area in the higher zone.