Poultry Manure Compost Alleviates the Phytotoxicity of Soil Cadmium: Influence on Growth of Pakchoi (Brassica chinensis L.)

The growth performance of pakchoi (Brassica chinensis L.) in relation to soil cadmium (Cd) fractionations was investigated to evaluate the remediating effect of poultry manure compost on Cd-contaminated soil. A yellow-brown soil (Alfisol) treated with various levels of Cd (0-50 mg Cd kg(-1) soil) was amended with increasing amounts of compost from 0 to 120 g kg(-1). Compost application transformed 47.8%-69.8% of soluble/exchangeable Cd to the organic-bound fraction, and consequently decreased Cd uptake of pakchoi by 56.2%-62.5% as compared with unamended soil. Alleviation of Cd bioavailability by compost was attributed primarily to the increase of soil pH and complexation of Cd by organic matter including dissolved organic matter. In general, the improvement of pakchoi performance was more pronounced in higher Cd-contaminated soil. Addition of large amount of compost also favored the anti-oxidative capability of pakchoi against Cd toxicity. This low cost remediation method seems to be very effective in the restoration of Cd-contaminated soils.