Gypsum in Improving the Use of Phosphate Fertilization for Soybean Crops

Abstract

ABSTRACT The improvement of the chemical conditions of the soil in the subsurface is indicated as an alternative to increasing soybean yields because it is related to greater efficiency of water and nutrient use, such as phosphorus (P). The study aimed to evaluate the soil chemical changes and the soybean yield due to the application of P and gypsum. For this, a field experiment was conducted between 2017 and 2020 under a Humic Cambisol in Southern Brazil. The treatments were composed of four corrective rates of P2O5 (0, 50, 100, and 200 kg ha−1) associated or not with agricultural gypsum (0 and 1400 kg ha−1). In the first year of evaluation, there was an increase in soybean yield with gypsum, and rates of P. In the absence of P correction, root length density was higher in the 20–30 cm layer. There was a linear increase in P available in the topsoil (0–10 cm) as a function of the nutrient rate. With gypsum application, there was an increase in calcium (Ca) and reduction of magnesium (Mg) in the 0–10 cm layer, besides the increase of sulfate (S-SO4 2-) in all layers. The application of agricultural gypsum promotes chemical changes in the soil at depths of up to 40 cm and gains in soybean yield, even without altering the efficiency of P use by plants.