ENZYMATIC-ACTIVITIES IN AN ARID SOIL AMENDED WITH URBAN ORGANIC WASTES - LABORATORY EXPERIMENT

This work studied the changes in soil oxidoreductase and hydrolase act ivities during 360 days of incubation of an arid soil amended with dif ferent amounts of organic materials (fresh and composted urban organic wastes). The enzymatic activities were stimulated by such amendments. The soil receiving sewage sludge showed the highest overall activity. The different enzymatic activities rose after amendment then decrease d rapidly with time; 360 days after organic amendment, the sail receiv ing the highest dose showed significantly higher enzymatic activity th an the unamended soil. The soil amended with compost showed lower; tho ugh more stable, overall enzymatic activity than the soils amended wit h fresh wastes (municipal solid waste and sewage sludge). The sail rec eiving organic material to raise its organic matter content by 0.5% di d not generally show significant differences from the unamended soil, while the differences produced in the soils receiving organic material to raise their organic matter content by 1.5% were still significant 360 days after amendment. (C) 1998 Elsevier Science Ltd. All rights re served.