Agronomic efficiency of phosphates fertilizers on soybean

Abstract

An experiment was conducted during two years in a Dark-Red Latosol in the county of Jaboticabal, SP, Brazil, with the objective of verifying the effects on the soil, on the plant and on soybean grain yield, of four phosphates fertilizers (triple superphosphate, fused magnesium phosphate, rock granulated phosphate of Gafsa, rock phosphate of Patos de Minas), applied on the rates of 100 and 200 kg/ha of P₂O₅. Fertilization with phosphorus resulted in increased grain yield and in the contents of P in the soil and in the plant. The efficiency of the P sources was according to the following decreasing order: triple superphosphate, fused magnesium phosphate, rock granulated phosphate of Gafsa and rock phosphate of Patos de Minas. An important observation was that the efficiency of the rock granulated phosphate of Gafsa was considerability higher when the residual effect of the second year was considered, whereas the rock phosphate of Patos de Minas was not efficient to supply P to the plants. The fused magnesium phosphate did not modify significantly the pH value and the contents of Ca and Mg in the soil and in the leaves.