Decomposição residual de culturas de safrinha e adubação fosfatada na cultura da soja

Abstract

The dynamics of the nutrients in the soil and the utilization of these by the crops is quite variable. In this context, phosphorus is one of the nutrients that deserves greater attention in fertilization planning due to its low natural availability, strong interaction with most types of cerrado soils, and export by the species cultivated in these systems. The objective of this work was to evaluate the effect of the residual decomposition of corn, brachiaria, millet and corn intercropped with Brachiaria, on the agronomic performance of soybeans under different doses of phosphorus. The experiment was conducted in a randomized complete block design with four replications. The plots were composed of four production systems (1-corn / soybean, 2- brachiaria / soybean, 3- corn intercropped with brachiaria / soybean, 4 millet / soybean) and the subplots for three doses of phosphorus in soybean sowing 100%, 75% and 50% depending on the amount recommended for the soybean crop after analysis). It was evaluated the persistence of the straw and the release of macronutrients from the residues of the species that preceded the soybean crop, in addition to the components of soybean production and grain yield. The data were submitted to analysis of variance. For persistence of straw and macronutrient release the means of the treatments of factor of production systems were compared by the Tukey test at 5% of probability and the collection times adjusted to mathematical functions at 5% of probability. For the other variables the averages were compared by the Tukey test at 5% probability. The second harvest millet had the highest values of biomass produced between the systems, as well as a higher reduction percentage. There was no significant interaction between second crop crops and phosphate fertilization. The lowest rates and release rates of N, P, K, Ca, Mg and S were found in the maize crop, which reflected in the lower number of pods per plant, grain mass and grain yield of soybean. Dose of phosphorus, the highest yield of soybean grains was obtained.