Características do pasto e efi ciência agronômica de nitrogênio em capim-tanzânia sob pastejo contínuo, adubado com doses de nitrogênio

Abstract

The experiment evaluated the effects of nitrogen (N) levels (100, 200, 300, 400kg ha-1) on sward characteristics, and agronomic effi ciency of N on Tanzania grass pastures (Panicum maximum Jacq. cv. 'Tanzânia-1') with continuous grazing method. The design experimental used was completely randomized with two replications. Three tester Nellore (Bos indicus) young bulls per pasture with N level of 100kg ha-1, and four tester Nellore young bulls per pasture of the other N levels, with 300kg initial weight grazed continuously from 10 November 2001 to 15 April 2002 Sward height levels at experimental pastures were maintaining at 60cm with adjusting of stocking rate. The herbage mass, green leaf mass, green herbage mass, and culm mass, increased linearly as the N fertilization increased. Negatively linear relationship was found between the N fertilization and leaf/ culm ratio. The culm proportion increased and dead material decreased on sward structure with increased N levels applied at pasture. There were no effects of N levels on green leaf proportion at sward structure. N applications in Tanzania grass pastures change sward characteristics. The agronomic effi ciency of N defi ned in terms of dry matter (DM) accumulation/kg of N applied decreased with the increase of N levels.