Indicadores de qualidade física para argissolos sob pastagens nas regiões leste e sul de Minas Gerais

Abstract

The use of unsuitable animal stocking rates, with weight overload cause changes in the soil structure, and it is in the superficial layers that the greatest effects of animal trampling show. This work aimed to detect structural changes in soils managed with different grazed systems in eastern and southern regions of Minas Gerais, by means of estimated index of the water retention curve. We used a completely randomized design, where four tillage systems were analyzed: 1- South Minas Gerais Pastures, 2- East Minas Gerais pastures under regular grazing pressure, 3- East Minas Gerais Pastures under strong grazing pressure and 4- an area under natural forest as control) all on an Argissolo Vermelho-Amarelo. Topsoil samples with preserved structure were collected in triplicate and submitted to the determination of the soild physical and hydraulic properties such as: water retention curve, bulk density, total porosity, macro and microporosity, available water capacity, distribution pore size and S index. The soil under native forest showed better structural quality than pasture soils. In the Eastern region of Minas Gerais, the land use with grassland under strong pressure of grazing caused degradation of soil structure, confirmed by the indicators of physical quality, S index and pore distribution size. The S index values were higher in managements Forest and South Minas Gerais Pastures, indicating better structural soil conditions in these environments.