Cycling and availability of P for soybean in rotation with Brachiaria as a species of cover crop

Abstract

Brazilian soils are deficient of phosphorus as a result of the source material and the strong interaction even with the ground. The use of no tillage promotes the increase of organic matter in surface horizons, due to the deposition of mulching, changing the dynamics of soil phosphorus. and recently has been attributed to the characteristic of braquiaria available phosphorus to subsequent crops. The study this work will be to evaluate is the effect of braquiaria culture as species of covering in the ciclagem and availability of P in the system, as well as in soybean response to phosphorus fertilization in no-till system.The experiment will be conducted at the Experimental Farm Lageado the Faculty of Agronomic Sciences, UNESP-Botucatu, Sao Paulo State in the Department of Plant Production. The experiment will consist of 3 initial treatments (Natural sources of phosphorus and soluble and one control), presence or absence of braquiaria and 3 levels of phosphorus in soybean planting. This will be conducted in an area with no-till crop rotation for seven years, and braquiaria introduced in the last three years. Will be taken soil samples at the time of soybean planting (after desiccation of the braquiaria) for analysis of fertility and determining the forms of phosphorus in the soil. The dry matter of braquiaria will be carried at 15, 30, 60, 90 and 120 days. On soybean plants will be analyzed the accumulation of phosphorus, leaf analysis, grain yield and dry matter production in the system. The results will be submitted to the analysis of variance and the averages compared for test t (DMS) 5% of error probability. (AU)