Influência de períodos de pastejo em trigo duplo propósito sobre a decomposição e liberação de nutrientes da palhada em sistema de integração lavoura-pecuária

Abstract

The aims of this work were to evaluate the influence of dual purpose wheat grazing periods on plant decomposition rates and nutrient release (N, P, K, Ca e Mg) and soybean yielded cultivate in sequence in no-till systems. Treatments were laid out as a random block design with two replications. The treatments were six grazing periods (0, 21, 42, 63, 84 e 105 days), on continuous stocking rate grazing method. From these treatments, dual purpose wheat biomass and nutrients decay constants were evaluated along 7 different field incubation periods (0, 15, 35, 63, 98, 139 e 196 days after soil deposition) by the litter bag technique. The percentage of biomass and nutrients at the easily decomposable compartment increases with the increase of grazing periods, due to the influence of the animal over the plants tissue turnover, which results in highest decomposition rate and nutrients release to the soil and consequently to the soybean cultivated in sequence on crop-livestock system. However the soybean grains yielded reduced with the increase grazing periods mainly due to the diminished of dry matter residue over the soil.