Potencial do Granito Valsungana: Fonte de K e Sustentabilidade na Agricultura

Potential of Valsungana Granite: Source of K and Sustainability in Agriculture

Abstract

: Brazil, one of the largest food producers, imports around 93% of the potassium chloride used in agriculture. This study
explores silicate rocks, specifically the Valsungana Granite (GV), from Major Gercino, Nova Trento and Brusque, SC., as an
alternative source of potassium. The main objective was to evaluate the solubility of potassium through technological routes, including
comminution and calcination at 710°C, with and without the addition of CaCl2.H2O. The samples were treated with aquous solutions
(pH 5.7 and 7.3), acids: citric, nitric and oxalic and melich-1. Potassium solubility occurred in all samples, the most effective being
calcined with the addition of salt, under oxalic acid solution, followed by citric acid, melich-1, and aquous solutions with pH 5.7 and
7.3. Potassium concentration was determined by atomic absorption. The characterization of the “in natura” granite and the calcined
granite without and with the addition of flux (CaCl2·2H2O) were carried out using X-ray diffraction and fluorescence, scanning
electron microscopy and infrared spectroscopy. The results indicated ion exchange and chemical reactions, demonstrating the p otential
of GV as a source of potassium fertilizer and suggesting the need for further studies on the availability of K in the soil.

Keywords: Potassium; Sustainable agriculture; Valsungana Granite