Abstract: The migration and bioavailability of heavy metals in polluted soil are dependent on their solubility, which could be affected by many factors including organic manure incorporation. With wheat and rice straw as materials, an incubation experiment was conducted under flooded soil condition to investigate the effects of straw incorporation on the solubility of Cu and Cd in soil, and the relationships between the solubility and soil dissolved organic carbon (DOC). The results showed that straw incorporation could significantly enhance the solubility of Cu and Cd in soil, and the concentrations of Cu and Cd in soil solution increased with the incorporation rate of straw. Compared with that of Cd, the solubility of Cu was more sensitive to straw incorporation. The peak concentrations of Cu and Cd in wheat straw treatment were 98% and 31% higher than those in rice straw treatment, respectively, while the peak concentration of soil DOC in wheat straw treatment was approximately 40% higher than that in rice straw treatment. A significant positive correlation was observed between the solubility of soil Cu and Cd and soil DOC. The solubility of Cu was more sensitive to soil DOC concentration, and the enhancing efficiency of soil DOC to Cu solubility was approximately 4 times of that to Cd solubility.

Key words: Stellera chamaejasme population, Age structure, Root crown, Survivorship curve, Population regeneration