The study was conducted based on the rigourous long-term experiment on the permanent meadow, immediately after its's renovation and after 15 years. The aim of this study was to determine the changes occurring in the soil richness in potassium, it's pH, species composition and management of potassium, calcium and magnesium in meadow sward. The experiment compared the effects of three levels of mineral fertilization on 120, 240 and 360 kg Nźha-1 levels and two levels of organic-mineral fertilization on 240 and 360 kg Nźha-1 levels. The ammonium nitrate, triple superphosphate and potassium salt was applied in mineral fertilization. The cattle slurry covered needs with the account of potassium in organic-mineral fertilization, nitrogen and phosphorus were filled up to full doses in above given mineral forms. Water deficiencies were supplemented through the irrigation on all objects. 15 years after the renovation a rise in the potassium content was found out in the higher soil layers and increasing the participation in meadow sward of short and middle grasses with cost of tall grasses on all objects, what was expressed with reducing yields. In spite of the increasing potassium content in the soil, its reduction in the meadow sward and the worsening ratio of K:(Ca and Mg) followed, attesting the decreasing fodder value.