Adubação fosfatada em sistemas de produção de soja

Abstract

Phosphorus is one of the main nutrients in fertilization planning, due to its low natural availability, strong interaction with most types of Cerrado soils and export by species. The use of cover crops prior to soy planting provides differences in the dynamics of nutrients in the soil and in the use of these by the plants. Thus, the present work was carried out in the experimental area of the Federal University of Goiás - Regional Jataí with the objective of evaluating the effect of residual decomposition of corn, Urochloa ruziziensis, millet and corn intercropped with Urochloa ruziziensis, on the agronomic performance of soybeans with different doses of phosphorus. The experimental design was randomized blocks, in a 4x3x2 factorial scheme, with four replications. The plots consisted of four production systems (corn / soybean; Urochloa / soybean; corn intercropped with Urochloa / soybean and millet / soybean) and three doses of phosphorus in the sowing of grain-producing crops (100%, 75% and 50 % depending on the recommended amount for the crop) in two agricultural years (2018/2019 and 2019/2020). The following variables were evaluated: straw production and persistence of species that preceded soybean grown, macronutrients concentrations in the leaves of soybean plants, the biometric components (plant population, plant height, height of first pod insertion, stem diameter, number of pods per plant, number of grains per pod and mass of 1,000 grains) and soybean grain yield. The data obtained were subjected to analysis of variance and the significant differences were subjected to the Tukey test at 5% probability. The production systems that have Urochloa ruziziensis, single or intercropped with corn, had higher straw production, with the Corn / Soy system with the highest decomposition rate. Therefore, Maize + Urochloa / Soy production system provided the highest number of pods per plant, number of grains per pod, reflecting the higher soybean grain yield. The number of pods per plant was higher in the dose of 100% in the agricultural year 2019/2020, indicating a possible depletion of P levels in the soil in the other treatments.