Utilization of Vermicomposts in Soil Restoration: Effects on Soil Biological Properties

Increasingly, organic soil amendments are being examined for their potential use in soil restoration and for preventing soil erosion. Two vermicomposts, differing in their chemical nature (obtained from cow dung, CD, and green forage, GF), were applied annually for a period of 3 yr to a Xerollic Calciorthid soil located near Seville (Guadalquivir Valley, Andalusia, Spain) to evaluate the efficiency of these organic amendments in soil restoration, Their effects on the plant cover and biological properties (microbial biomass, soil respiration, and enzymatic activities such as dehydrogenase, urease, beta-glucosidase, phosphatase, and arylsulfatase) of the soil were determined. The organic wastes were applied at 3 and 6 Mg C ha(-1), respectively. After 3 yr of successive soil amendment, the application of CD vermicompost to the soil had a greater effect on the soil biological properties than GF vermicompost, The final soil microbial biomass C, dehydrogenase, urease, beta-glucosidase, phosphatase, higher in CD-amended soils than in the GF- and arylsulfatase values were 28.3, 25.9, 12.6, 26, 12, and 14.2% amended soils. This may hive been due to a greater labile fraction of organic matter in the CD than the GF vermicompost; however, the results obtained for the enzymatic activities stabilized in humic matrix mitigated that the highest values occurred in the soils amended with GF vermicompost with respect to those amended with CD vermicompost. This increased formation of enzymes immobilized in soils humic matrix may prolong any increase in soil enzymatic activities and plant cover produced by the amendment.