Qualidade de tecnosolo sob diferentes métodos de recuperação de áreas degradadas por mineração de caulim na Amazônia oriental.

Abstract

Technosol is an alternative for recovering areas degraded by mining, as the topography of the land is reconstructed with tailings from mining and processing, creating an environment for fauna and flora and disposing of waste. However, in order to fulfill the ecosystem services of a natural soil, the Technosol must be of good quality. With this in mind, the aim of the study was to evaluate the chemical, physical and microbiological indicators of a Technosol in different methods of recovering areas degraded by kaolin mining after three years in a given site condition. The experiment was set up at the IRCC mine in 2020 with the following treatments: nucleation (NU), dense planting (PA), forest planting (PF), forest planting with liming (PFC) and a native forest (FN) as a reference ecosystem. The soil was collected in July 2023 at depths of 0-10 cm and 10-20 cm in four 25x25 m plots in each treatment and in the FN. In the first chapter, the chemical indicators were assessed: pH, organic matter (OM), potassium (K), phosphorus (P), calcium (Ca), magnesium (Mg), aluminum (Al), potential acidity (PA), sum of bases (SB), cation exchange capacity (CEC), base saturation (V), aluminum saturation (m), and the physical indicators: soil density (DS), total porosity (PT), penetration resistance (RP), sand, silt and clay, and the soil quality index (IQS). The physical indicators were little altered in the Technosol, with the exception of PR which was positively affected in the PA, while the chemical indicators showed higher pH, Ca, Mg, SB and V values, and lower Al and m values in the PFC. Higher PT and lower DS and RP were observed in the FN. In addition, the FN had higher MO, AP, CTC, P, K, Al and m values. The IQS in the PFC was higher in the Technosol and was equal to the FN at a depth of 10-20 cm. Therefore, the chemical characteristics were positively altered by liming. However, the characteristics studied are still not close to those of the FN. The second chapter looked at oxidizable carbon (CPOx), organic carbon (CO), microbial biomass carbon (CBM), basal respiration (RBS), organic carbon stock (ECO), microbial quotient (qMIC) and metabolic quotient (qCO2). CO was not influenced by the treatments, while E-CO and CPOx were altered by NU and PA, with the highest values. For CBM and RBS, the highest values were at a depth of 10-20 cm, in NU and 10-20 cm in PA in CBM and PA=NU in RBS. For qMIC, at 0-10 cm it was highest in NU and PFC and at 10-20 cm in PA. qCO2 was highest in PF at a depth of 10-20 cm. Thus, for the indicators studied, the Technosol differs from the native forest. However, nucleation stands out from the other treatments.