Efeito de doses de nitrogênio, intervalos de corte e irrigação sobre a produção, composição química e digestibilidade do capim-estrela (Cynodon nlemfuensis)

Abstract

This work was carried out in the county of Valença - RJ, with the objective to evaluate production and quality of the stargrass, in function of: two irrigation levels (with and without); four cut intervals (21, 28, 35 and 42 at the rainy season and 28, 35, 42 and 49 days at the dry season of the year); as well as four levels of nitrogen (0, 150, 300 e 600 kg/ha/year). The dry matter production (DMP) and the efficiency of the nitrogen utilization (ENU) in plots of 6,25 m2, were estimated from October 2004 to October 2005. In the months of January, June/July and September/October samples were collected to determine chemical composition and digestibility such as: crude protein (CP), neutral-detergent fiber (NDF) and in vitro dry matter digestibility (IVDMD). The Irrigation when increased DMP and ENU, reduced the forrage quality and only had significative effect (P<0,05) during the rainy season. The harvest intervals does not affected (P>0,05) on DMP. However, there was tendency to increase. Harvest intervals should be 42/49 days to obtain good forage quality and yield. The chemical composition and digestibility of the dry matter decreased with the spacing of the cuts and the effect of the interval of cuts on ENU was dependent of the irrigation. At that time it dries the irrigated treatments had her ENU increased with the decrease of the frequency of the cut. The nitrogen fertilization was the only factor that increased (P<0,05) DMP and the quality of the stargrass. However, the answer of DMP to the nitrogen fertilization was reduced and ENU was not affected in function of the nitrogen levels. In the conditions of experiment was realized, it is approved as the most appropriate handling of the studied factors: The interval of cuts of 42/49 days, that formed an alliance high yield with a satisfactory quality and the irrigation, only accomplished in favorable climatic conditions.