Fracionamento de N no solo e na cultura da soja manejada em sistema de semeadura direta com rotação de culturas

Abstract

Sandy soils, such as the west paulista region, have some limitations for growing plants, such as the low content of clay and organic matter in the soil. The challenge from this is to accumulate organic matter in sandy textured soils to improve the production system conditions. The aim of this study was to evaluate the dynamics of nitrogen and carbon in a distroferric Red-Yellow Argisol in management system rotation/succession crops of maize, lupine, Urochloa brizantha (syn. Brachiaria) and soybeans combined with N rates in no-till system. The experiment was installed and conducted at the Faculty of Agricultural Sciences at the University of West Paulista - UNOESTE in Presidente Prudente/SP, following a randomized complete block design with four replications in a split plot, the plots consisted of three crop rotations (Maize/Lupine/Fallow/Soybean, Maize plus Urochloa brizantha/Soybean; Urochloa brizantha/Soybean) and the subplots by four N rates applied annually (50, 100, 150 and 200 kg ha-1). The main crops rotated were: hybrid corn AG 5055, soybean farming BMX Power RR and forage Urochloa brizantha (syn. Brachiaria) cv. MG-5. We evaluated the total N content and N-inorganic (NH4 + and NO3) of soil, soybean leaves, corn and Urochloa and straw; NH3 volatilization; total C content; and the contents of C and N soil microbial biomass. The management of crop rotations and N levels did not influence the N content in the soil and in the plant, but the highest concentrations of N and C soil found at 0-20 cm.