Original scientific paper 10.7251/AGSY1404175T EFFECT OF ADDITIONAL FERTILIZING WITH NITROGEN ON FORAGE YIELD IN RED CLOVER -ITALIAN RYEGRASS GRASS -LEGUME MIXTURE

The high and stable yields of good quality forage on lawns can be achieved with proper fertilization and rational utilization. The aim of this study was to analyze the impact of the additional application of nitrogen fertilizer in red clover-Italian ryegrass grass-legume mixture on forage yield, hay yield and the proportion of red clover, Italian ryegrass and weeds in the total hay yield. The field experiment was set up 2011 th in Cacak (Serbia) on fluvisol soil type, acid reaction (pHH2O 4.8), using a randomized block design with three replications and experimental unit 5x1m. Together with the primary tillage in the autumn, the soil was entered 300 kg ha -1 N15P15K15. Red clover cv. K-39 and Italian ryegrass cv. Tetraflorum were seeded at 20 cm inter-row spacing, both with 12 kg ha -1 seed. The experiment included two treatments: without fertilization (control) and additional application of nitrogen fertilizer (KAN - 27 % N) in the rate of 40 kg ha -1 early in the spring 2012 th and 2013 th . Additional application of nitrogen did not significantly increase yields of forage and hay in all cuts in both years. In the second year, nitrogen fertilization led to a significant increase in the share of Italian ryegrass in the hay, with a proportional decrease of red clover and weeds, in both cuts. This may be due to the pronounced competitiveness and faster growth of Italian ryegrass in relation to red clover, especially in drought conditions. In the third year of cultivation, there were no plants of Italian ryegrass and additional feeding resulted in a significant increase in the proportion of red clover in the hay, at the expense of reducing the share of weeds.