USO DE POLIHALITA NA ADUBAÇÃO DA SOJA E SEU EFEITO RESIDUAL NA PRODUÇÃO DE MILHO

Abstract

The soybean-corn succession is the main grain production system in Brazil. This system is extremely demanding in fertility, so that the management of fertilization is essential to supply nutrients in a balanced way and guarantee productivity at a lower cost. Polyhalite is a K mineral source and other nutrients, recently explored on a large scale, which can be used as a fertilizer for plant production. The aim of this study was to evaluate the effect of a granulated fertilizer based on polyhalite on soybean fertilization and its residual effect on corn in succession. The experiment was carried out in a Red Latosol area, in random blocks, with four replications and five treatments, standardized by the amount of K2O (80 kg ha-1) and provided in the soybean seeding: KCl, Polihalita, KCl + Polihalita blend in 72/28 proportion, KCl plus limestone and gypsum, and a control treatment. The production parameters, both for soybean and corn in succession, were not altered by the treatments. The total grain production of the soybean-corn system, however, was higher with the polyhalite application. The K export by soybeans was higher with the polyhalite use. In the corn crop, the nutrients export in the grains did not differ between treatments. Only the polyhalite use resulted in a positive balance of Mg in the system (+ 2.51 kg ha-1). The application of polyhalite and / or KCl or KCl with gypsum and limestone, proved to be adequate to avoid a negative balance of Ca and S by grains in the soybean-corn system. The Mg and K levels in soil differed only in the topsoil, with higher levels in the treatments KCl Plus, polyhalite and KCl + Polyhalite. The Ca levels in soil with 20-40 cm layer were higher with polyhalite use. The S levels did not differ between treatments in the evaluated layers