Relatório do Estágio Supervisionado Obrigatório - Avaliação de pós de rocha quanto à dissolução e liberação de nutrientes in vitro

Abstract

In recent years, the challenges of climate change and soil degradation, aggravated by intensive agriculture, have driven the search for sustainable practices. The use of rock powders as fertilizers presents itself as a promising alternative, due to the slow release of nutrients, reducing losses due to leaching and pollution. This study aimed to characterize and evaluate the solubility of basalt rock powders (PR-01) and actinolite-talc schist (AP-C1) in organic acid solutions (acetic, citric, lactic, malic and oxalic) and in distilled water. Chemical and mineralogical characterization was performed by X-ray fluorescence (XRF) and X-ray diffractometry (XRD). Additionally, samples of the rocks originating from the two powders were impregnated with resin and made on thin slides for petrographic descriptions by optical microscopy. The dissolution experiments quantified pH, electrical conductivity and sodium and potassium contents in the extracted solutions. The results indicated that citric acid was the most efficient in potassium extraction in the PR-01 sample, while acetic acid stood out in the AP-C1 sample. The total chemical analysis by ICP-AES revealed that the AP-C1 sample exceeded the allowed limit for lead (200 ppm), stipulated by Normative Instruction No. 5/2016 of MAPA, making it unsuitable for use as a remineralizer. On the other hand, basalt rock dust has shown great potential as a remineralizer, due to the slow and continuous release of nutrients, minimizing losses and favoring sustainability. Future studies should evaluate the dynamics of other elements in vitro and in vivo, as well as agronomic efficiency in the field, contributing to the development of low-carbon and decarbonization technologies.