Decomposição e liberação de nutrientes das palhadas de milheto e milheto + crotalária no plantio direto do feijoeiro

Abstract

The objective was to evaluate biomass production, accumulation and release of macronutrients, and the decomposition of straws of pearl millet (Pennisetum typhoides (Burm.) Stapf) and pearl millet plus Crotalaria juncea intercropping, in field condition, under dry bean, sowed in February (summer/autumn). The experimental design was randomized blocks, with four replications, in a split-plot arrangement, with the straws in the plots and evaluation periods in sub-plots (0, 8, 16, 24, 40, 56 e 72 days after seeding). The collected residues were dried to determine the remaining dry matter, then ground and sent to laboratory in order to determinate macronutrient contents. By the contents and remaining dry matter amounts, the remaining nutrient amounts were determined, expressed as percentages of the initial amounts. Nonlinear models were fit to the values, choosing the best adjustment. The pearl millet plus Crotalaria juncea intercropping provided the largest biomass production. The straw from intercropping accumulated and released the largest macronutrients quantities, except for sulfur. The single millet presented the fastest nitrogen release speed.