Influence of nitrogen and phosphorus on Brachiaria decumbens stapf. production

This experiment was conducted to evaluate the DM production, leaf: stem ratio, CP content and leaf and stem efficiency response to nitrogen of Brachiaria decumbens Stapf. grass, fertilized with different N and P doses during the summer period. A completely randomized experimental design was used, with three replicates in a 4 x 3 factorial arrangement, composed by four N doses ( 0, 100, 200 and 300 kg/ha/year), using ammonium sulfate, and three P2O5 doses ( 0, 50 and 100 kg/ha/year), using super simple phosphate. The K amount applied was 40 kg/ha/year. The cuts ( at 20 cm of the soil) were performed every 28 days, in a total of three cuts during the experiment. After each cut, fertilization was accomplished according to the treatment. N fertilization affected DM production, that showed maximum values of 5,345.6 and 4,857.7 kg/ ha of leaf and stem, respectively. Leaf: stem ratio was greater (1.31) with 200 kg/ha N dose, independent of the phosphorus dose. N fertilization had quadratic effect on CP content of the leaves and linear effect on CP content of the stem. P fertilization, however, had no effect on these variables. The N efficiency of utilization had quadratic effect when increasing N doses were used. The point of maximum was 245.3 kg of N, dose that provided 18.84 kg of DM/kg of N.