THE EFFECT OF INCREASING DOSE OF VERMICOMPOST APPLICATION ON CADMIUM CONTAMINATED SOILS ON SOME SOIL ENZYME ACTIVITIES

Abstract

Contamination of agricultural soils with heavy metals is a major problem in soil quality. When heavy metals reach food chain through agricultural soils and plants, they pose a great threat to the health of humans and other living organisms. The enzymes are generally less active in contaminated soils due to exposure to heavy metals. The aim of this research was to investigate the effect of increasing vermicompost doses on some biological soil properties in artificially contaminated soils. In the study, increasing doses of vermicompost (0-2.5-5-10%) were added to soil artificially polluted with Cd (0, 5 and 10 mg.kg-1). Untreated soil was used as a control. After the vermicompost application, the soils were brought to 70% of the field capacity and incubated at 28-30oC in laboratory conditions. Samples were taken from the incubated soils at 0-5-10-15-30-45-60-75-90-120th days. Alkaline phosphatase, arylsulfatase, dehydrogenase, urease, catalase enzyme activities were analyzed in soil samples at the end of each incubation period. The effects of increasing doses of vermicompost application to artificially contaminated soils on some biological properties of the soil showed differences, and these differences were found to be statistically significant (p<0.01). The lowest values of soil enzyme activities (alkaline phosphatase, arylsulfatase, dehydrogenase, urease and catalase enzyme activities) were determined in soil samples contaminated with Cd and not treated with vermicompost until the end of incubation. The highest enzyme activities values were found in soils contaminated with 5 and 10 mg.kg-1 Cd that were treated with 10% vermicompost. Enzyme activities in incubated soil increased with increasing doses of vermicompost. It was determined that the addition of vermicompost to soils contaminated with Cd significantly reduced the toxic effects of Cd.