Efeito do uso e manejo sobre a erosão e atributos de solos da sub-bacia das Posses, Extrema-MG

Abstract

The present research was carried out with the purpose of studying the impacts of land use and management on soil attributes and on water erosion, as well as to use the P index model in the environmental risk assessment of P transference from soil to the streams in the Posses catchment, Extrema, Minas Gerais. The losses of soil, water and soil constituents were evaluated through erosion plots installed in several management systems. The results showed that reforestation and well-managed pastures are strategies that minimize the effects of water erosion and that safeguarding native forest mainly in Litholic Neosols is essential for the conservation of the pedoenvironments, especially in steep slopes. The effect of management on soil quality was verified by the quantification of the organic carbon fractions stored in the soil and the carbon management index. The positive effect of reforestation, well-managed pastures and conservation of vegetation on soil quality is evidenced by the carbon management index. This index and the particulate organic carbon have great potential as watershed management tools. The P index model was tested in a pioneering way to evaluate the P transfer risk form soil to the Posses streams, as well as to predict the impacts of land use changes on this transfer. The results obtained lead to the conclusion that, although almost all of the catchment has a low P index, eucalyptus and agricultural areas should receive greater attention regarding the use of fertilizers. Also, the simulations allowed predicting that creating “Environmental Protection Areas” can reduce the P transfer risk to stream waters, even in pasture areas that were fertilized. The results of this study can serve as incentive and management tool for the judicious use of fertilizers and conservation practices in the Posses catchment.