Acúmulo e liberação de fósforo em sistemas de produção de soja no cerrado mato-grossense

Abstract

The phosphorus cycling using system of grain and cover crops aims to make the nutrient available to the crop in succession. The objective of this work is to evaluate grain and cover crops in production system in phosphorus cycling, in the aerial part of the crops and their influence on soybean productivity in SPD. The experiment was carried out during the agricultural year 2015/16, being the second year of cultivation, at the Experimental Station of the Federal University of Mato Grosso, in a dystrophic Oxisol. Conducted in a randomized block design with nine production systems and four replications in experimental units of 7m x 9m. In the second season, crop coverage and soybean crop were used as commercial culture, the other treatments were: S1: Fallow in no-tillage (NT), S2: Fallow Conventional Planting (CP), S3: Crotalaria spectabilis, S4: Corn + C. spectabilis, S5: Pennisetum glaucum, S6: Urochloa ruziziensis, S7: Sunflower + U. ruziziensis, S8: Vigna unguiculata and S9: Maize + U. ruziziensis. The treatments U. ruziziensis and sunflower + U. ruziziensis promote the highest cycling of P in the aerial biomass and result in intermediate productivity. Sunflower + U. Ruziziensis accumulated a greater amount of P in flowering and senescence and exports less to the grains. C. Spectabilis was the treatment with the lowest cycling of P for the system and this does not explain the higher soybean yield. Isolated P is not a determinant factor for higher soybean productivity.