Efeito de níveis de adubação nitrogenada pós-corte sobre o rendimento e o valor nutritivo de gramíneas do gênero Cynodon

Abstract

The experiment was conducted under field conditions at the Department of Animal Science of the Federal University of Lavras (UFLA), MG, during the period between November/98 and March/99, with the objective to evaluate dry matter yield, crude protein level and yield, in vitro digestibility coefficient of the dry matter; NDF, ADF and Ca, P, Mg, K and S leveis of Coastcross grasses (Cynodon dactylon (L)Pers x Cynodon nlemjuensis Vanderyst}, Tifton 68 (Cynodon spp) and Tifton 85 (Cynodon spp), submitted to four nitrogen levels (0, 100, 200 and 400 kg/ha), as ammonium sulphate, broadcasted. The soil in tibe experimental area was a Distrophic Dark Red Latosol. At the beginning of the experiment, the soil was corrected and at the occasion of the planting, in november/98, a basic fertilization was applied with P and K. The experimental design utilized was a randomized blocks with six replications and the treatments were arranged in a spht plot scheme. The plots were made up with grasses and subplots with nitrogen levels; 3 cuts were executed with 42-days intervals to evaluate the parameters. Nitrogen fertilization enhanced both dry matter yield and crude protein content of the grasses studied; caused a decrease in the NDF content, but it did not change either the ADF content or in vitro digestibiliy coefficient of the dry matter. Mineral contents averaged within intervals were capable of minimizing or eliminating the need for mineral supplementation. Tifton 85 was better than the others, followed by Coastcross. The greatest rates of nitrogen utilization were obtained with 100-200 kg/ha of N, and for apparent nitrogen recovery best results were obtained with 400 kg/ha of N.