Remineralizadores de Solo Como Fontes Alternativas de Potássio na Cultura da Soja

Abstract

Brazil's high dependence on the importation of potassic fertilizers has encouraged the search for alternative sources of potassium (K), such as aluminosilicate rock powders, including soil remineralizers. In this context, it is essential to evaluate the agronomic efficiency of these materials, considering their compositional variability and reactivity, as well as the different cultivation conditions across the country. This study aimed to characterize and assess the agronomic efficiency of four soil remineralizers produced in Minas Gerais (Verdete, Phonolite, Kamafugite, and Basalt) and to evaluate four extractants in the prediction of available K in treated soils.. The mineralogical composition was determined by X-ray diffraction. Under field conditions, with soybean cultivation, the four remineralizers were tested in addition to a control treatment (no K addition) and a reference source (KCl). The effects of the treatments on soybean yield, K accumulation, and the performance of extractants for available forms of this nutrient were evaluated. The treatments were arranged in a randomized block design with five replications. Each useful plot measured 2.5 x 8 meters, and 25 plants were collected per plot to estimate yield. For the analysis of extractants, five soil samples were collected per plot from the 0–20 cm layer. The results indicated that verdete and phonolite had the highest K contents, while basalt showed the lowest. In the field, KCl resulted in the highest yield increase (26%), followed by verdete (10%). Acid extractants such as Mehlich-1 and Mehlich-3 were more efficient in extracting K from soils treated with remineralizers. It is concluded that remineralizers have potential as alternative sources of K, but their effectiveness is limited by low short-term reactivity. The study reinforces the need for further research to optimize the use of these materials in agriculture, aiming for reduction in dependence on imported fertilizers.