Effects of nitrogen fertilization on the production of Panicum maximum cv. IPR 86 under grazing

The experiment was conducted at the Experimental Station of Paranavai/IAPAR-PR-Brazil, from October 1998 to May 1999, to evaluate the effects of N fertilization on Panicum maximum cv. IPR 86 pastures. Four doses of N (0; 150; 300; and 450 kg.ha(-1).year(-1)) were applied to pastures under rotational grazing with grazing cycles (GCs) of 40 days (5 days-grazing and 35 days-rest). It was used a randomized complete block design, with split-plots, and two replications per treatment, being the N-doses studied in the main plots and the GCs in the sub-plots. In all GCs the variables dry matter of available green leaf-blades (GLB) and dry matter of stems + leaf sheaths (GSLS) increased linearly (P<0.01) with the increase in N-doses during a grazing period of 200 days. The average residual GLB and GSLS were 335; 730; 825; and 837, and 104; 1024; 1817; and 2763 kg.ha(-1), respectively for the N-treatments of 0; 150; 300; and 400 kg.ha(-1).