Productivity of natural grassland of the order Arrhenatheretalia depending on nitrogen fertilization level

Natural grasslands are major animal feed resources in the moutainous region of Serbia. Proper use of mineral fertilizers in these grasslands can lead to a multiple increase in productivity. The paper analyzes the effect of NPK fertilizers with different levels of nitrogen (unfertilized - A0; N60:P40:K40 - A1; N100:P40:K40 - A2; N140:P40:K40 - A3) on forage yield and botanical composition of natural grassland of the Arrhenatheretalia order on the slopes of Mount Kopaonik. With the increase of the amount of nitrogen applied in spring from 40 to 80 kg ha-1, forage and hay yields also increased, whereas further increase innitrogen quantity to 120 kg ha-1 resulted in the absence of the increasing yield trend. In the second cut, there were lower forage and hay yields compared to the first cut. A total of 50 different plant species of 44 genera and 20 families were identified on the grassland. In both cuts, in all fertilized treatments, the grass percentage was significantly higher than the control. The percentage of legumes in the first cut was low, while it significantly decreased in the second crop with the increase in the level of fertilizer. The percentage of other plants was higher in the second cut, as compared to the first one, and it significantly decreased in both cuts with the increase in fertilizer rate.