Rendimento e estado nutricional do capim-braquiária, em função da interação fósforo e magnésio em um latossolo amarelo do Recôncavo da Bahia

Abstract

The experiment was carriel in the School of Agronomy in the municipal district of Cruz of the Almas-BA, in the period of October of 2001 to April of 2002, in soil classified like Yellow Latossolo Coeso, with the objective of evaluate the dry matter production, concentration and accumulation of phosphorus, magnesium, nitrogen and gross protein in the Brachiaria decumbens. The treatments were set as a randomized block design in a 7x3 factorial scheme with there replications. It was tested seven rates de phosphorus (0; 25; 50; 100; 200; 300 and 400 Kg.ha-1) combined with there rates de magnesium (0; 40 and 80 Kg.ha-1). The test crop in the grass, being the first to the 85 days after the initial fertilization and the second to the 94 days after the first court, separating the plant tops in the component leaf blades and stems+sheaths. They were appraised the production of dry matter, concentration and accumulation of phosphorus, magnesium, nitrogen and gross protein in the plant tops well as in the components (leaf blades and stems+sheaths). The obtained results indicated that the interaction phosphorus and magnesium increased the revenue of dry matter of the plant tops, even so, the revenue in the stems+sheaths went superiors to the from the leaf blades. The match concentration in the plant tops in the first court, was superior that in the second. With the increase of the phosphorus rates the Brachiaria presented growth in the concentration of magnesium, in the first court. In the largest rates of magnesium (80 Kg.ha-1) it was obtained the smallest concentrations of nitrogen in the first growth cycle, even so the concentrations of gross protein in this court they were the highest. The phosphorus accumulation, magnesium and nitrogen presented growth of the concentration with the increase of the phosphorus rates, in the first court, however, in the behavior was quadratic. The gross protein presented larger accumulation in the plant tops in the first growth cycle.