Nitrogen status evaluation of grass-legume swards under four N fertilization levels

Abstract

Forage grass-legume mixture are highly productive ambience of different plant species intended for animal nutrition. The competitiveness of species in the mixtures is one of the important traits that significantly affect grassland management. The goal of the study was to evaluate nitrogen nutrition index of pure lucerne and their mixtures with grasses and sainfoin subjected to four different levels of nitrogen in three years duration. The experiment had a randomised block design with four replicates and eight treatments. Examined treatments were pure lucerne crop and mixtures of lucerne, orchard grass, tall fescue and sainfoin in the same proportion and four nitrogen fertilization rates (0, 70, 140, 210 kg ha-1). Pure lucerne achieved higher yield by 12.8% than their mixtures. Forage production was the highest at 210 kgN ha-1 which was 14.6% more than treatments without nitrogen. Nitrogen uptake by the plant that were fertilized with N was significantly higher than the plants that were not fertilized. In all three experimental years control nitrogen treatment had satisfactory value of nitrogen nutrition index while other N treatments showed luxury consumption. Soil N reserves and nitrogen fixation in the treatment where N was not applied, were sufficient to ensure enough biomass production.