Influence of nitrogen and phosphorus on Brachiaria decumbens stapf. production

Albertí Ferreira Magalhães Aureliano José Vieira Pires Gleidson Giordano Pinto de Carvalho Fabiano Ferreira da Silva Ronaldo Silva Sousa Cristina Mattos Veloso About the authors

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.

crude protein; fertilization; leaf:stem ratio; roughage; nitrogen utilization efficiency

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