The effect of compost, inoculation with native soil microbes and their residual effects on bioavailability of nickel by peas (Pisum sativum L.) and radish (Raphanus sativus L.) grown on polluted soil were investigated in pot experiments. Plants were amendment with different compost levels (0, 0.2, 0.4, 0.6% of soil dry weight) and inoculated with different native soil microbes (4 fungal species, one bacterial species, 4 species of arbuscular mycorrhizal fungi) isolated from the polluted soil under study. Significant increases in the biomass of pea and radish plants were observed as a result of amendment application and their residual effects. The mycorrhizal dependency (MD) of pea plants was lower than of radish plants. The highest reductions of Ni levels in both plants were observed by the simultaneous applications of compost with microbes or mycorrhizal fungi to polluted soils. Soil pH increased significantly (p < 0.05) as a result of applying native microbes especially with arbuscular mycorrhizal fungi (AMF) alone or combined with compost. The DTPA extractability of soil Ni was significantly decreased with increasing soil pH (p < 0.05). The minimum transfer factor of Ni from polluted soil were 0.067 and 0.089 for pea and radish plants, respectively which were attained as a result of applying compost (0.6% of soil weight) inoculated with mycorrhizal fungi. From the results, we can conclude that the use of compost and native soil microbes as a soil remediate could be an effective strategy for soil remediation.
