Atributos físicos indicadores da qualidade do solo sob sistemas de manejo na bacia do alto do Rio Grande-MG

Abstract

The agriculture use causes alterations on the soil physical attributes. That a alterations usually indices a deterioration of its quality, due to removal of the canopy and excessive use of the mechanization. This work aimed to evaluate the alterations of soil physical properties as indicators of soil quality of a typic Acric Red-Yellow Latosol (Oxisol), under different management systems, compared to the native vegetation. Soil samples were collected at the 010, 1020, and 2030-cm depths in the region of Campos das Vertentes, at the Alto do Rio Grande, MG. The evaluated attributes were: aggregate stability in water, expressed for the geometric mean diameter, bulk density, and porosity. The following management systems were evaluated: conventional tillage with potato (CTP); conventional tillage with potato, followed by oat in rotation with corn (CTPOC); conventional tillage with corn (CTC); no-till with corn (NTC); eucalyptus forest (EF); and native vegetation (NV). The bulk density increased in the systems CTPOC and NTC, compared to the native vegetation. The total volume of pores was reduced in the systems CTP, CTPOC, and NTC, even within the short growing time of the systems CTP and CTPOC. The conventional systems CTP, CTPOC and CTC did not change the soil aggregate stabilty enough to differ of the native vegetation. The systems with less canopy removal are establishing a new equilibrium condition. The slighter soil tillage, the higher organic matter content, and the grass root aggregating action in the systems NTC and EF were benefic for the soil quality. The penetration resistance was reduced in the superficial layers in the conventional systems, CTP, CTPOC, and CTC, due to the soil till. There were no significant differences in permeability of soil to water among the management systems (CTP, CTPOC, CTC and NTC), with the values ranging from 35,4 to 54,6 mmh-1 being classified as slow to moderate; these values were rather inferior than the equilibrium system (NV).