Diagnóstico da qualidade do solo em áreas de extração mineral de calcário utilizando indicadores físicos e químicos

Abstract

Soil is a fundamental natural resource for the conservation and development of the environment and ecosystems, being at the same time important in economic and industrial activity, through the extraction and processing of ores present in the subsoil. In this sense, there is still little information found related to the quality of the soils under the influence of the limestone mining process in the municipality of Caçapava do Sul (RS), using physical and chemical indicators as evaluation parameters. Considering that the variation in conditions in the supply of water and soil nutrients is a factor that contributes to plant growth, the objective of this study was to evaluate the quality of soils in three different areas and managements in a mining company, using physical and chemical indicators, quantifying the nutrient elements of the soil in the existing physical conditions and identifying the potential use of the waste pile area in the development of plant species. Soil sampling in each area was carried out randomly and at a depth of 0–20 cm, to determine the chemical attributes of pH, organic matter, exchangeable calcium, magnesium, potassium and aluminum content, phosphorus, zinc, copper and manganese, determining the base saturation values, cation exchange capacity, and physical attributes of granulometry, density and hydraulic conductivity of the soil. The chemical results obtained were interpreted through values used in the literature, and related to the cultivation of forest species, and demonstrated that the analysis of the surface layer of the soil in the area of native forest and eucalyptus plantation have better chemical attributes, in addition to physical conditions, carrying a well-developed vegetation and greater natural balance, while in the tailings area with constructed soil, there are greater physical and nutritional restrictions. The soils in the areas showed high values of pH, base saturation and cation exchange capacity, low availability of acidic hydrogen in the soil, and low concentration of aluminum in the phytotoxic form. There was a greater difference in relation to organic matter, phosphorus, density and hydraulic conductivity in the native area in relation to soils built in a waste pile. There is a strong relationship between OM and soil CTC present in the most conserved areas. The determination of the attributes allowed to quantify the nutrient chemical elements available in the superficial layer of the soil, and their availability in the absorption by the plants, in determined physical conditions, demonstrating the quality of these soils from the nutritional point of view in the development of the plants of these areas.