Effects of organic matter on the forms of added Cd and its dynamic transformation in soil with or without growth of rice

The effects of rice straw and Chinese milk vetch on the forms of added Cd and it’s dynamic transformation in soi1 with or without growth of rice were studied．The results show that rice straw and Chinese milk vecth can significantly reduce Ex(exchangeable)-Cd content in the soi1 without growth of rice．The formation of CdS under extremely low Eh condition is the important mechanism for Ex-Cd content．while the influences of rice straw and Chinese milk vetch on the forms of added Cd and it’s dynamic transformation are apparently different After one-month incubation，rice straw and Chinese milk vecth can decrease Ex-Cd content and increase the Sob(strong organic bound)-Cd and Mn(Mn oxide bound)-Cd contents in the,soil with growth of rice．With the elapsing of time．Mn-Cd and Sob-Cd are released and transformed into Ex-Cd．