Atributos químicos de um latossolo e produtividade de soja e milho em sistema de consórcio milho e Brachiaria brizantha cv. Marandu em função de fontes de nitrogênio

Abstract

The aim of this work was to evaluate the productivity of maize and soybean under the influence of consortium between corn and Brachiaria brizantha cv. Marandu with application of different nitrogen sources and evaluate changes in the chemical properties of Oxisol after nine years of cultivation system in corn intercropping with Brachiaria under different nitrogen sources in topdressing. The experiment was established in Maracajú-MS municipality in the agricultural years 2005-2013, in Oxisol. The factors studied were: corn intercropped with Brachiaria brizantha cv. Palisade and single corn; and the use of nitrogen sources (without nitrogen, urea, urea + ammonium sulphate and ammonium sulphate) arranged in a factorial 2 x 4, in a randomized block design with four replications. The experimental plots had dimensions of five meters wide by twelve meters long. The Brachiaria brizantha cv. Marandu spacing of 0.20 m and was later planted corn in the same area at a spacing of 0.80 m. The soil samples were collected through the opening of trenches and collected up soil at depths of 0-5, 5-10, 10-20 and 20-40 cm. The corn intercropping with Brachiaria brizantha cv. Marandu does not influence the yield of corn is used since the proper amount of fodder seeds. The nitrogen sources in the doses provided increased productivity in corn second crop in succession to soybeans in the years 2005, 2006, 2011 and 2012, and the nitrogen fertilization provides greater effect on the productivity of maize in years water availability. Soybean yield on plant residues of maize intercropped with Brachiaria brizantha cv. Marandu provides earnings on average of 331.5 kg ha-1. Nitrogen fertilization has a high potential for acidification and promotes the reduction of calcium, magnesium and potassium. Changes in chemical characteristics are more strongly altered by the sources of nitrogen in the soil surface layers. The adoption of maize + Brachiaria brizantha cv. Marandu provides improvement in soil chemical properties, mainly in the surface layer.