Effects of Wheat Straw and Lead on Cadmium Remove in Rice-Soil Systems in Different Texture Soils

The experiments of rice cultivated in sandy and clay soil columns were conducted under outdoor condition to investigate the effects of wheat straw and lead on cadmium remove in rice-soil systems in artificial Cd-contaminated soil. The results of the study indicated that the content of cadmium in rice reduced gradually with growth and development. Both of wheat straw and lead promoted the rice to absorbed cadmium and increased the content of cadmium in rice, which the impact of lead was greater than wheat straw. The acceleration in different growth periods showed different in sandy and clay soil. Wheat straw and lead promoted the cadmium transported into grain and increased concentration factor in the Cd-contaminate soil. Compare to cadmium single treatment, the content of cadmium and concentration factor of rice grain increased by 44.00%, 36.00% and 41.67%, 50.00% respectively in sandy soil and 58.62%, 43.00% and 46.15%, 61.54% in clay soil. Cadmium entered into soil and removed downward with water flow and the migration ability of cadmium in sandy soil was greater than clay soil. With increasing of soil depth, the content of cadmium became less and less, while the soil depth in 40～60 cm of the clay soil and 60～80 cm of sandy soil, the content of cadmium was similar with blank control. Wheat straw and lead reduced the migration ability of cadmium in clay soil, which was greater than sandy soil in rice season.