EN
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.