DOSES AND FORMS OF PHOSPHORUS APPLICATION IN SOYBEAN IN A FIRST CULTURE AREA IN THE CERRADO

Abstract

In cerrado soils, the low availability of phosphorus (P) is one of the factors that most limits soybean
productivity and its restriction causes irreversible damage to the crop. For this reason, proper management of phosphate fertilization is essential to achieve satisfactory productivity. The primary objective of the study was to evaluate phosphorus doses and application methods in soybeans in a first cropping area in the Cerrado. The experiment was conducted in the field using a randomized block design, with a 4 x 3 factorial scheme, in which four doses of phosphorus (26, 52, 78, and 104 kg ha-1 of P) were tested in three application modes, in the furrow planting, by broadcast with shallow coverage and combined incorporation (50% in the furrow and 50% by broadcast), with three replications. It measured - plant height, first pod insertion height, stem diameter, number of grains per pod, weight per thousand grains, and production. Regardless of the dose, the mode of phosphorus application in the planting furrow resulted in higher averages for plant height (82.3 cm), first pod insertion height (23.9 cm), and stem diameter (7.3 cm). Application in the furrow and combination had similar productivity levels, with an approximate average value of 1.800 kg ha-1. Yield showed a quadratic response as a function of P doses for furrow (R2 99.6%) and combined (R² 88.9%) application modes, with the highest response dose of 111.9 kg ha-1 of P and estimated productivity of 2,337.74 kg ha-1 for furrow application, and 97.4 kg ha-1 of P, with estimated productivity of 2,070.40 kg ha-1, for combined application. The broadcast application mode showed a linear response (R2
98.9%), with an increment of 16.18 kg ha-1 in productivity for each 1 kg ha-1 of P applied to the soil, according to the model. Therefore, under the conditions of the current experiment, the broadcast fertilization mode was inferior to the furrow and combined fertilization modes. Thus, it is possible to use in-furrow and combined fertilization for phosphorus fertilization in areas of Cerrado’s first cultivation.