Óxidos: uma alternativa ao calcário na correção da acidez do solo

Abstract

Most Brazilian soils are naturally acidic due to the weathering process over time. To correct this acidity, limestone is generally used, which is applied to the surface of the soil in areas under direct planting, correcting only the first few centimeters of soil. The objective was to evaluate the efficiency of oxides in relation to limestone in correcting soil acidity. The experiment was carried out in Giruá, RS, in a Red Oxisol. 5 treatments were used in a randomized block design (without amendment, ¼ SMP limestone, 1 SMP limestone, ¼ SMP oxide and 1 SMP oxide) applied superficially to soil under a direct planting system for almost 30 years. The limestone used was PRNT 78% dolomitic limestone and the oxide has PN 170. After applying the correctives, corn (Zea mays) was planted. At crop harvest, productivity, thousand grain weight (PMG) and soil pH were evaluated in layers 0–5 and 5–10 cm. The ¼ SMP oxide treatment was the one that showed the highest productivity and the ¼ SMP limestone treatment was the one that showed the highest PMG, but both did not differ significantly from the treatment without corrector. After corn harvest, the application of 1 SMP oxide and 1 SMP lime increased the soil pH of the 0-5 cm layer from 5.1 to 6.2 and 5.8, respectively. None of the treatments were efficient in correcting acidity in the 5–10 cm layer during the crop cycle. The application of correctives increased corn productivity by an average of 1175 kg ha-1 compared to that without corrective, however, it did not differ significantly. The application of oxide provided a higher financial return compared to the application of dolomitic limestone. The use of oxide was more efficient in increasing soil pH compared to limestone, but did not influence corn productivity. In the increase in pH over time, the oxide was superior until 19 days of incubation, at 89 days there was no statistical difference between oxide and dolomitic limestone.