Liberação de K por micaxisto como remineralizador

Abstract

Brazil's external dependence on potassium fertilizers is growing and worrying, which in 2021 consumes around 96% of the total K consumed in agribusiness. Such dependence, associated with recurrent increases in the prices of these commodities, encourages the internal search for sources of K, with emphasis on soil remineralizers. Despite recent legal advances regarding the use of remineralizers in Brazil, there is still a great lack of robust studies on the effects of these materials on the soil in the short and long term. Thus, the objective of this research was to evaluate the rate of K release from a Micaschist-based Remineralizer in a long-term experiment. In addition, the effect of liming and ammonium acetate extractor on the tasting of this rock powder was also evaluated. Therefore, in a randomized block design, with four replications, the effect of five doses of Micaschist (0; 3.24; 6.48; 12.96 and 25.92 t/ha) and an additional treatment ( dose 12.96, without liming). The experimental unit consisted of a drum (180 dm³) filled with soil. The mixture of rock powder with soil was carried out only in the superficial layer (0-20 cm). Before and after 29 months of soil incubation with the Remineralizer, under natural conditions, the soil sample was collected with the aim of experimenting with the exchangeable content of K in the ammonium acetate extractor. The results revealed that there was no effect of liming on the rate of K release, as well as there was no effect of the extractor on gasoline from Micaschist. Only 5.8% of the rock's total K was released during the incubation period. Extrapolations of the experimental data revealed that the increment of 1 t/ha of Micaschist increased the exchangeable content of K in the soil by approximately 1.0 mg/dm3. It is concluded that the evaluated material has low efficiency as a potassium fertilizer.