Brachiaria brizantha (Syn. Uroclhoa brizantha) cv. Marandu under different doses of nitrogen and phosphorus in Humaita-AM, Brazil

The objective of this study was to evaluate the productive capacity of Brachiaria brizantha (Syn. Uroclhoa brizantha) cv. Marandu, submitted to different doses of nitrogen and phosphorus. For that, tests carried out under field conditions in the municipality of Humaita-AM. The experimental design was in randomized blocks, in a 4x4 factorial scheme, with 4 nitrogen doses: 0; 100; 200 and 300 kg ha(-1) and 4 nitrogen doses: 0; 100; 200 and 300 kg ha(-1) of phosphorus: 0; 100; 200 and 300 kg ha(-1) and one control (without fertilization), with 4 replicates. The analyzed variables were green and dry biomass, in two cuts with interval of 57 days. The plants responded with linear growth at increasing doses of nitrogen and phosphorus during the first cut, while the residual effect on the second cut observed only for higher doses of phosphorus. There is no response to phosphate fertilization when nitrogen is not applied and the linear growth of the plants as a function of different nitrogen doses is significantly lower when the phosphorus is not applied.