Long-term experiments fertilization were carried out in 1987-1995 years period. In experiments the yield of DM and effectivity of nitrogen fertilizer were investigated. The doses of nitrogen fertilizers were 0, 80, - 160, 240 and 320 kg N/ha, phosphorus fertilizers 100 kg P₂O₅ per ha and potassium fertilizers 150 kg K₂O per ha. Among other things was investigated the effect of N-fertilization on the floristic composition of meadow sward. The experiments were localized on the six-years permanent meadows in Łukowe (400 meters above sea level). The yield of DM systematically increased, but only to the 240 kg N per ha. The best efficiency obtained at 80 and 160 kg N per ha. The nitrogen fertilization increased the share in floristic composition such species as Cocksfoot - Timothy and Annual meadow - grass. The participation of Meadow fescue in yields was very stable.
Ten years were carried out experiments which started in 1987 on the six-years permanent meadows in locality Łukowe (400 m/a.s.l.). The doses of nitrogen fertilizers were 0, 80, 160, 240 and 320 kg N/ha. Whereas phosphorus and potassium doses were 100 kg P₂O₅ and 120 kg K₂O/ha. The yield of total protein systematically increased with the increase of nitrogen doses, and the differences between yields of nitrogen fertilizer treatments were significant. The increase of nitrogen fertilizers doses had negative influence on the content (in I cut) of phosphorus, potassium and calcium, but positive influence on the magnesium, sodium, total and N-NO₃ nitrogen content. The N-NO₃ content in yield of meadow hay was in non - toxic level.