Effect of Apple Pruning Vermicompost on Improving some Biological Properties of a Pb-Contaminated Soil

Lead (Pb) is one of dangerous environmental contaminated factors which threaten the health of plants, animals and humans. Lead in the soil led to reduce the biological activities of soil. The aim of this study was to evaluate the effect of vermicompost (C) of apple pruning wastes on microorganism’s activity of a Pb-contaminated soil. For this purpose an experiment was carried out in greenhouse condition as a factorial experiment based on a randomized completely design with two factors including Pb concentration in four levels (0, 250, 500 and 1000 mg Pb kg-1 soil) and vermicompost in three levels (0, 20 and 40 t ha-1). A soil sample was selected and spiked uniformly with different concentrations of Pb. These samples were incubated for 90 days, and then some biological experiments were measured. Results showed that by increasing the Pb concentration in soil, BR, SIR and MBC were reduced intensively, but these indices were improved by adding the vermicompost. Using 20 and 40 t ha-1 vermicompost increased BR up to 1.95 and 2.33 times higher than control treatment, respectively. MBC at 40 t ha-1 vermicompost application treatment on average was 3.18 times higher than control treatment. The amount of qCO2 increased up to 2.6 times in C20 (20 t ha-1 vermicompost) treatment compared to control. Therefore it could be concluded that application of vermicompost ameliorate the toxic impacts of Pb on microorganisms activity.