Atributos físicos, químicos e biológicos do solo em ambientes de voçorocas no município de Lavras - MG

Abstract

In the southern region of Minas Gerais large areas are affected by gully erosion. The evaluation of soil properties in these environments is extremely important, in view of their sensitivity to changes in soil quality. The objectives of this study were to evaluate physical, chemical and biological soil properties and their relationship with vegetation in the gullies. The study examined three gullies, one on an Inceptisol and two on Oxisols- LVA1 and LVA2, in Lavras, Minas Gerais (SE Brazil). Different environments of the gullies were evaluated including the river bed, an intermediate position without vegetation (TMSV) and an intermediate position with vegetation (TMCV) that were common to the three gullies. Other environments found in two gullies on LVA2 were also assessed: an intermediate position with eucalyptus (TMEucalypt) and an intermediate position with Candeia (Eremanthus incanus) (TMCandeia), as well as areas under native vegetation (NV), adjacent to each gully, as reference. Of the physical properties, the most affected were the total pore volume, macro and microporosity and bulk density (Ds). Water erosion has caused a sharp decrease in soil fertility, expressed by the reduction of Ca2+, Mg2+, K+, P, and organic matter contents, as well as increases in the levels of Al3+, H + Al and Al saturation (m). Of the biological properties, microbial biomass C decreased more than 80 % in the environments TMSV in LVA1, Inceptisol gullies and river bed under LVA2, compared to their respective reference areas. The qCO2 proved to be a sensitive index to environmental changes; highest values †were found in the bed, caused by excess moisture and in TMSV, due to low organic matter content and absence of vegetation. The decrease in the number of spores of mycorrhizal arbuscular fungi was greater than 75 % in most degraded environments. Results show the sensitivity of the analyzed soil properties to environmental changes in gullies and can serve as indicators for monitoring the dynamics of environments degraded by water erosion.