Adubação sistêmica e modos de aplicação de fósforo na produtividade de soja

Abstract

The objective of this work was to evaluate the possibility of fertilization inversion, reconciling with phosphate fertilization to launch into soybean crop, as well as the best combination of the P2O5 dose between winter and summer crops, in a very clayey soil with low phosphorus content. The treatments were four installments of the total dose (120 kg of P2O5) recommended p for soybean crop (0, 25, 75 and 100%), applied in winter and/or summer, combined with two forms of application of the same (line and pitch), in an oat/soybean succession. The experimental design used was randomized blocks, with three replications, totaling 24 plots. The portionings of the P dose were applied to launch in the 24 plots in oats (winter). In the summer, in 12 plots the P was applied in the groove before soybean planting and the remaining 12 plots received the respective doses of P to throw. For phosphate fertilization, the following portions of the p dose (120 kg P2O5ha-1) were used: (0% - 100%), (25% - 75%), (75% - 25%) and (100% - 0%), in the form of Super Simple Phosphate, being the first value applied in winter and the second in the summer period. The yield components evaluated in soybean were: final plant stand, insertion height of the first pod, number of pods per plant, number of grains per plant, mass of 1,000 grains (g) and total grain production (kg ha-1). No significant differences were obtained between treatments for all yield components, except for total grain production. Soybean production was higher in treatment with 100% of the P dose in the groove, evidencing that in low fertility soils it is not recommended to inversion fertilization or phosphate fertilization to toss. It is recommended to inversion fertilization only in corrected fertility soil.