Microbial biomass and activity in a Brazilian soil amended with untreated and composted textile sludge

This laboratory study examines the effect of application of untreated and composted textile sludge on microbial biomass and activity in a Brazilian soil. The soil was amended with untreated and composted sludge at rates equivalent of 6.4t ha(-1) (0.64 g per 100g of soil) and 19t ha(-1) (1.90 g per 100g of soil), respectively, and were incubated at 28 degrees C for 60 days and daily sampled for microbial activity. An additional experiment, in the same condition, was conduced for evaluation of microbial biomass and enumeration of microorganisms at 15, 30 and 60 days after incubation. The application of composted sludge increased significantly the microbial biomass and activity, and bacteria number of soil. There were not differences in the microbial activity and bacteria number among the control and untreated sludge amended soils. In conclusion, after 2 months of incubation, the effects of the two amendments on soil microorganisms were: microbial biomass, soil respiration and bacteria number were increased only in composted sludge treated soil. qCO2 and fungi number were not affected by untreated and composted sludge.