Abstract: In order to explore a new resource utilization way of vermicompost and mussel shell and effectively control heavy metal pollution in farmland, using pure vermicompost （V） as matrix material, the vermicompost-based composite inhibitor was prepared by adding pure mussel shell powder （S） and modified shell powder （SC）. Then the vermicompost-based composite inhibitor was applied to the Cd contaminated soil planted with amaranth, aiming to study the effects of V and its composite inhibitors on the plant growth and Cd content in amaranth as well as Cd transformation in soils. The results showed that the application of V and its composite inhibitors could promote the growth of amaranth and reduce the Cd content in its edible parts and roots, with much better effects being found after the application of vermicompost based composite inhibitors. Both V and its composite inhibitors could reduce the content of available Cd in soil and its bioavailability coefficient, and the vermicompost based composite inhibitor at the level of 10% had much better reduction effects, but no obvious changes were found for Cd speciation after V and its composite inhibitors application.

Key words: vermicompost, mussel shells, Cd, retarding effect, soil