Immobilization and phytotoxicity of Cd in contaminated soil amended with chicken manure compost

The experiment was conducted to evaluate the effect of compost application on the immobilization and biotoxicity of Cd in winter wheat (Triticum aestivum L.) potted soils. Soils treated with various levels of Cd (0-50 mg Cd kg(-1) soil) were amended with 0, 30, 60 and 120 g compost kg(-1) soil. The fractions of Cd in soil were evaluated by a sequential extraction procedure. Compost application resulted in more than 70% lower soluble/exchangeable Cd (KNO(3)) but increased the concentration of organic-bound (NaOH) and inorganic precipitates (EDTA) Cd in soils. Addition of compost was effective in reducing the phytotoxicity of Cd by decreasing more than 50% Cd uptake by wheat tissue and improving wheat growth. Alleviation of Cd phytotoxicity by compost was attributed primarily to the increase of soil pH, complexation of Cd by the organic matter and coprecipitation with P content. Compost was effective in the immobilization of Cd in soils and can be used to remediate Cd-contaminated soils.