The distributions of microbial biomass carbon (MBC), enzymes activities and readily mineralizable carbon were evaluated across soil aggregates recovered from a Dark-Red Clayey Oxisol in areas under native Cerrado vegetation and where no-tillage (NT) and conventional tillage (CT) management systems have been established for 21 years. Soil samples were collected at a 0 to 5 cm depth and aggregates were prepared using a wet sieving procedure. The size classes 8.0 to 2.0 mm, 0.5 to 0.25 mm and 0.25 to 0.106 mm and samples denominated sum of aggregates (SA) were selected for biological determinations. In relation to the native Cerrado the agricultural systems caused the disruption of macroaggregates and losses of MBC. As compared to the CT, the reduced soil tillage, the accumulation of organic matter and the localized application of fertilizers in the NT system favored higher levels of acid phosphatase and arylsulfatase in its aggregates and SA samples. NT microaggregates and SA samples presented higher levels of MBC as compared do the CT. The highest activities of beta-glucosidase were also found in the NT macro and microaggregates. The NT and CT management systems influenced the distribution profile, in soil aggregates, of the biological properties evaluated. Acid phosphatase, beta-glucosidase and arylsulfatase activities were higher in the NT macroaggregates, in spite of the evenly distribution of MBC in the three aggregate size classes evaluated. In the CT, only beta-glucosidase presented an uneven distribution in macro and microaggregates.
microbial biomass; readily mineralizable C; soil enzymes; acid phosphatase; beta-glucosidase; arylsulfatase
