Fontes de nitrogênio na produção de Brachiaria brizantha cv. xaraés

Abstract

This study aimed was to evaluate the effect of nitrogen fertilization with different doses and nitrogen sources on the production and bromatological composition of Brachiaria brizantha cv. Xaraés. The experiment was carried out at Fazenda Talitha located in Monte Gordo, Camaçari - BA, lasted 380 days, and was divided into three periods (rainy / dry transition with 123 days, dry period with 97 days and rainy period with 160 days). It was used a completetely randomized block design, with a 3x2x4 factorial arrengement, being three experimental periods (water / drought, drought and water transition), two nitrogen sources (urea and urease inhibitor urea) and four N.ha-1 doses. Year (0, 80, 160 and 240 kg N. ha-1) being divided in four applications (two at the beginning of the rainy season and two at the end of the rainy season that corresponds to higher temperatures in the region and with good rainfall, using 20, 40 and 60 kg N.ha-1 respectively) in addition to the treatment that did not receive nitrogen fertilizer. The accumulation of forage per cycle had a significant effect for interaction between period of the year and nitrogen doses. The crude protein content (PB) of the forage in the rainy / dry transition period had a significant effect on the interaction between grazing cycles and nitrogen doses (P<0.0001)and interaction source and nitrogen dose. The crude protein content of the forage in the rainy period showed a significant effect for the nitrogen source and for interaction between grazing cycle and nitrogen doses. Increases in nitrogen rates had a positive effect on forage accumulation and crude protein content of the forage produced. The effects related to the difference in the source of nitrogen used are associated with the greater climatic challenge. Other studies should be conducted with greater challenges to verify the efficiency of the use of urea with urea inhibitor in pasture.