Tannery sludge compost amendment rates on soil microbial biomass of two different soils

Abstract

Composting is recognized as one of the most cost-effective and environmentally sound alternatives for organic waste recycling. Long-composted wastes have the potential to substitute for inorganic fertilizers. We investigated the effect of tannery sludge compost (TSC) amendment rates on microbial biomass and activity in Brazilian soils. The soils (sandy and clayey soils) were amended with TSC at rates of 0 (control), 7.5, 15, 30 and 60 Mg ha(-1) (equivalent to 0, 0.3, 0.6, 1.2 and 2.4 g per 100 g of soil, respectively), incubated at 28 degrees C for 60 days. Soil Microbial biomass, soil respiration and enzyme activities were evaluated at 15, 30 and 60 days after incubation. The application of 7.5 Mg ha(-1) TSC significantly increased the microbial biomass and activity. There were no negative or positive effects by the application of 7.5 Mg ha(-1) on soil enzymes. The results of this study suggest that TSC increased soil microbial biomass and activity when it was amended at a low rate. on the other hand, the amendment with the TSC, in all rates, did not negatively affect the soil microorganisms and their activities. Crown Copyright (C) 2011 Published by Elsevier Masson SAS. All rights reserved.