AVALIAÇÃO PRODUTIVA DE FORRAGEIRAS EM DIFERENTES NÍVEIS DE ADUBAÇÃO

Abstract

In addition to having the largest commercial herd in the world with 212.8 million head, Brazil also has about 172 million hectares of pasture. Of the cultivated pastures, more than 70% were formed with forages of the Urochloa genus, however most of the pasture areas are in some degree of degradation. The objective of this study was to evaluate the productive performance of different forages for obtaining new varieties and their response through fertilization levels. The experiment was conducted at the Federal University of Tocantins (UFT), university campus of Araguaína-TO, at the School of Veterinary Medicine and Animal Science at the Center for Studies on Ruminant Production in the Legal Amazon (NEPRAL). The experimental design used was completely randomized, in a 4x3 factorial arrangement, with 4 forages and 3 levels of fertilization, with 3 replicates each. At the beginning of the experiment, phosphate fertilization was carried out and throughout the evaluations, the fertilizations predicted according to the treatments were performed, using the fertilizer formulated 20-00-20, totaling 100 and 200 kg / ha of N and K2O for medium and high. The criterion for carrying out forage evaluations was according to the number of leaves that appeared, and when the average obtained reached between 2.5 and 3 leaves that appeared, the evaluations were carried out. The height values were changed and differed between the evaluated factors, being the forage B172 and the high level of fertilization with the highest values. The Forage Accumulation (AcF) showed no statistical difference between the forages, however, it was observed that the forages that obtained the highest numerical values were those that had the highest heights, with height being a determining factor in increasing the production of forage mass. . However, the fertilization level treatment had a significant effect on the rate of forage accumulation (38.14, 58.17 and 88.37 kg DM / ha / day at low, medium and high levels, respectively). Forages B171, B173 and Marandu obtained similar tiller population density (DPP) (658.46, 715.68 and 583.21 tillers / m2, respectively), differing only from forage B172, with lower DPP (453.40 tillers) / m2). The defoliation criterion from the average of 2.5 live leaves / tiller was considered an efficient management strategy to obtain the data. The best fertility management was the high fertilization level, which promoted greater forage production, with reduced stalk and dead material participation and higher DPP, mainly due to the application of nitrogen, despite the greater height.