Crescimento inicial e produtividade da soja em sucessão a milho e braquiária, em intervalos de irrigação e classes de solo

Abstract

The purpose of this research was evaluate the initial growth and soybean yield in succession to corn and brachiaria in singles and intercropped systems, in differents irrigation intervals and two soil classes. The experiment was conducted at a non-acclimatized screened house, owned by Embrapa Western Agriculture, located in Dourados, Mato Grosso do Sul State, Brazil, in the years 2012 and 2013. In the first experiment, the experimental design adopted was a randomized block, in a split-plot arrangement with six replicates. There were evaluated two soil classes (dystroferric Red Latosol and dystrophic Red Latosol) in the plots and three types straw in the crops autumn-winter (single corn, single brachiaria, corn intercropped with brachiaria) in the subplots. In the second experiment, the experimental design adopted was in a split split-plot randomized block design with four replications. There were evaluated two soil classes (dystroferric Red Latosol and dystrophic Red Latosol) in the plots, three intervals between irrigations were used during the soybean flowering (each one day, two days and three days leaving the soil at 80% field capacity) in the subplots and three types straw in the crops autumn-winter (single corn, single brachiaria, corn intercropped with brachiaria) in the sub-subplots. In both experiments, each replicate corresponded to two soybean plants cultivated in polyethylene pots containing 20 liters of dystroferric Red Latosol or dystrophic Red Latosol, according to the treatment, collected at the experimental area of the Embrapa Western Agriculture, in Dourados, MS, and Fátima do Sul city, respectively. At the first experiment, were evaluated in the soybean at 20 days after emergence, plants height, stem diameter, total chlorophyll index, leaf number, dry mass leaves and stems. At the second experiment, in the soybean maturation the number and pods weight, grains number and yield per plant were quantified. It was observed highest initial growth soybean after to corn intercropped with brachiaria, both in dystroferric Red Latosol and dystrophic Red Latosol. With irrigation intervals of three and two days, in dystroferric Red Latosol and dystrophic Red Latosol, respectively, after single brachiaria provide greater soybean yield. Soybean plants grown in succession to single corn show lower initial growth and yield in both evaluated soils.