SILICATO NA CORREÇÃO DA ACIDEZ E DISPONIBILIZAÇÃO DE CÁLCIO E MAGNÉSIO NO SOLO

Abstract

Soil acidity is a limiting factor in the development of most cultivated plants. However, soil correctives can minimize or even eliminate problems related to acidity, such as high availability of toxic aluminum and manganese, high aluminum saturation and low availability of nutrients, such as calcium and magnesium. Several acidity correctives are commercially available and possess different chemical compositions and physical properties and, consequently, different efficiencies in correcting soil acidity. Thus, our objective was to compare the efficiency of calcium magnesium silicate as a soil acidity corrective to that of a dolomitic limestone. The research was carried out at the Instituto Federal Goiano - Urutaí Campus in Brazil, between August and November 2019. The experimental design was completely randomized with three treatments and eight replications. The treatments consisted of a control, application of calcium and magnesium silicate and application of limestone to increase soil base saturation from 10% to 60%. The correctives were mixed with soil from a very acidic dystrophic Oxisol (pH in water of 3.6). Then, after a 30-day incubation period, the following parameters were measured: pH in water, exchangeable aluminum, calcium and magnesium content, and base and aluminum saturation. Both correctives significantly increased soil pH, exchangeable calcium and magnesium content and, consequently raised base saturation above 60%. They also neutralized all exchangeable aluminum and therefore, aluminum saturation. Thus, calcium and magnesium silicate provided the same efficiency as limestone in neutralizing exchangeable aluminum and aluminum saturation in the soil and provided nearly equal efficiency in raising base saturation; limestone contributed to a greater supply of Mg2+, due to its higher MgO content.