Microbial and Enzymatic Activity in Soil After Organic Composting.

Microbial activity and biochemical properties are important indicators of the impact of organic composting on soil. The objective of this study was to evaluate some indicators of soil microbial and biochemical processes after application of compost (household waste). A Typic Acrustox, sampled at a depth of 10 cm under Cerrado biome vegetation, was evaluated in three treatments: control (soil without organic compost amendment) and soil with two doses of domestic organic compost (10 and 20 g kg^-1 soil). The following properties were evaluated: released C (C-CO₂): microbial respiration 15 days after incubation; microbial biomass C (MBC); total glucose (TG); metabolic quotient (qCO₂); and enzyme activity of β-glucosidase and acid and alkaline phosphatase. The application of household compost, at doses of 10 and 20 g kg^-1 Typic Acrustox, resulted in significant gains in microbial activity, organic C and C stock, as evidenced by increased MBC and TG levels. On the other hand, qCO₂ decreases indicated greater microbial diversity and more efficient energy use. The addition of compost, particularly the 20 g kg^-1 dose, strongly influenced the enzyme β-glucosidase and phosphatase (acid and alkaline). The β-glucosidase activity was significantly increased and acid phosphatase activity increased more than the alkaline. The ratio of β-glucosidase to MBC was greater in the control than in the composted treatments which suggests that there were more enzymes in the control than in the substrate or that the addition of compost induced a great MBC increase.