Applications of compost and wastewater sludge changes the biological activities in brown forest soil

Abstract

The use of agrochemical such as chemical fertilizers and pesticides has caused tremendous harm to the ecoenvironment. Organic matter (OM) addition to soil often leads to a rapid increase in the activities of various enzymes and reactivation of biogeochemical cycles in soil. One of the major concerns today in all over the world is the pollution and contamination of the soil. In fact hydrolytic enzymes are sensitive indicators of management induced changes in soil properties due to their strong relationship with soil organic matter (OM) content and quality. An experiment was conducted to study the impacts of combined fertilizer on soil properties in comparison with adding organic as solid waste compost (SWC) of plant origin or municipal wastewater sludge (MWWS) to sandy loam brown forest soil. Soil amendments were: control, 15 or 30 kg/ha dry organic fertilizer. Microbial compositions were determined by culture enrichment technique. Enzyme (β-glucosidase, cellulase, urease, and aryl-sulphatase) activities were estimated. Fluorescein diactate activity as well as physico-chemical properties as well as some microbial parameters were determined after 63 day of incubation under laboratory conditions. The results demonstrated that the SWC and MWWS significantly improved soil physico-chemical properties such as soil pH, moisture content, total C and N contents as well as biological properties. Accordingly, overall enzyme activities were substantially promoted in presence of both amendments and the higher increases were measured at 30% of SWC. Lower beneficial effects occurred at the combination of SWC and MWWS together at 30% possibly because of the increased the presence of trace elements through MWWS application. As a general response, SWC supplied at 30% seems to be a useful strategy to enhance biological activities of soil. Finally, soil biologic activities can be used as an index of soil fertility and organic fertilizer stimulates the natural soil microbiotas and reactivates the biogeochemical cycles.