AVALIAÇÃO DE FONTE ALTERNATIVA DE FÓSFORO PARA ADUBAÇÃO DO SISTEMA DE SUCESSÃO SOJA-SORGO GRANÍFERO

Abstract

The objective was to evaluate the productivity of the soybean-sorghum system in response to the application of a partially acidulated phosphate fertilizer, at different doses and modes of application. The study was conducted in São João da Paraúna – GO, in clayey soil, with a phosphorus content of 3.70 mg dm³ (Mehlich) in the 0-20 cm layer and 0.90 mg dm³ in the 20-40 cm layer. The experiment included three consecutive crops, starting with the 2021/22 soybean harvest, followed by grain sorghum cultivation in the 2022 season, and soybean in the 2022/23 harvest. The treatments included the application of a commercial product based on apatite phosphate rock (Arkophos Liber), applied alone and in combination with MAP, at doses of 1000, 2000, and 3000 kg ha⁻¹, in addition to a control treatment without phosphorus application. The applications were conducted pre-planting, with incorporation through harrowing and/or as maintenance application broadcasted in single doses during the 2021/2022 season. The treatments with Arkophos Liber, applied in the incorporated correction mode at a 28° angle, resulted in soybean grain productivity similar to that obtained with MAP at a dose of 200 kg of P₂O₅ ha⁻¹. These results indicate that Arkophos Liber can be a viable alternative in phosphate fertilization, provided it is correctly incorporated into the soil and applied at the appropriate dose. When applied as a surface maintenance broadcast, Arkophos Liber demonstrated greater efficiency at a dose of 3000 kg ha⁻¹, resulting in an increase of 4.43 sacks per hectare compared to the control treatment. This finding reinforces the importance of selecting the correct dose to optimize the efficiency of the product in this mode of application.

Keywords: Phosphate fertilization; Monoammonium phosphate; Apatite rock; Grain productivity.