Effects of wastewater sludge amendments on soil enzyme activities in earthworm cast

Abstract

Land application of sludge needs to be properly managed to avoid the detrimental effects on micro and macroorganisnns in the soil. Addition of sludge to the soil environment may impact earthworm activity, and in turn, soil productivity and health. In this study, two wastewater sludges which were different in origin (municipal and canned-food industry) were added to soil microcosms containing earthworms at different application rates. Alkaline phosphatase, dehydrogenase, beta-glucosidase and urease activities were measured in the earthworm casts collected from sludge-amended and control pots throughout a 30 day incubation period at 20 degrees C. These results suggest that sludge origin was the primary factor that influence soil ecosystems.