Mulching effects of composted msw on water percolation and compost degradation rate

Composted municipal solid wastes (CMSW) could potentially be used as a mulching material to control runoff and soil erosion. The effects of mulching with CMSW on water percolation and rate of compost decomposition were studied using laboratory rainfall simulator. Samples of typical loess soil (Calcic Haploxeralf) were packed in boxes and either covered with 0, 100, 200 and 300 m³ ha^-1 of CMSW, or mixed with 200 m³ ha ^-1 of CMSW. The soil boxes were subjected to six consecutive simulated rainstorms of distilled water, totaling 260 mm. Rate of CMSW mineralization and microbial activity were estimated from CO₂ evolution and dehydrogenase (DHG) and fluorescein diacetate (FDA) activities, respectively, during the drying periods between rain storms. With the surface CMSW treatments, 85 percent of the rain water percolated into the soil, compared with 42 and 52 percent in the control and incorporated CMSW treatments, respectively. Rate of CMSW mineralization, estimated from CO₂ evolution throughout the drying periods between six consecutive rainstorms, was 19, 13 and 11 percent of C added, in the 100, 200 and 300 m³ ha ^-1 of surface applied CMSW, respectively. The degradation of the compost had not ceased at the end of the experiment, as indicated by continuing enzyme activities and respiration simulated by the compost. Although 100 m ³ ha^-1 of CMSW was enough to control runoff efficiently in the laboratory, in the field, larger amounts may be needed to provide complete mulching of the soil surface.