Caracterização físico-química em solos agrícolas e florestais da Bacia Hidrográfica do Baixo Piquiri – PR

Abstract

The contents of metallic elements in soils are associated with geology and pedogenetic processes and may change due to anthropic actions. When metals accumulate in excessive amounts, they can generate effects on the nutrition or contamination of soils, plants and living beings, hence the importance of defining basic levels of natural soil quality through the determination of physicochemical parameters and the levels of metals. The Lower Piquiri Hydrographic Basin (BHBP) suffered heavy deforestation, aiming to create areas suitable for agriculture and livestock, affecting the environmental quality of the soils. Therefore, the work aims at the physicochemical characterization and determination of metallic ions available in eight samples of forest soils and in eight samples of adjacent agricultural soils, covering the soil classes Red Latosol, Red Nitosol and Red Argisol in the two rock formations ( Basalt and Sandstone). The analysis methodology for the soil samples was that of Embrapa (2017).Analyzes of soil texture, hydrogen ion potential, organic carbon, available phosphorus, calculation of organic matter and cation exchange capacity, and determination of metallic ions of iron, manganese, copper, zinc, calcium, magnesium, potassium and aluminum were carried out. The results obtained in this research are relevant in guiding the natural base levels of the BHBP soils, allowing the identification of possible environmental and human risks arising from the availability of metals. The pH of BHBP ranged from moderately acidic to practically neutral. CO and OM were higher in clayey soils when compared to sandy ones, mainly in forest. Base saturation (V%) of clayey soils was above 50% showing the high fertility of these soils. As for sandy soils, the average V% was less than 50% showing the low natural fertility of these soils. The metallic ion contents were higher in clay soil samples and lower in sandy soil samples. As for the use of clayey soils, the ion contents were higher in the forest samples, with the exception of Fe, Cu and Al, which were higher in the agricultural samples. In sandy forest soils, the contents of Mn, Zn, Ca and K ions were higher, whereas in agricultural soils the highest contents are of Fe, Cu, Mg and Al ions. Therefore, it is concluded that the physical characteristics-chemicals indicated levels related to geology, indicating the direct influence of the soil source material. The available metallic ions, on the other hand, had a regular distribution and no indications of anthropogenic sources in the soils