秸秆还田对镉污染农田土壤中镉生物有效性的影响

通过温室盆栽试验和土壤培养试验,研究了重金属镉污染水稻土和人为模拟镉污染土壤上不同种类和不同量的作物秸秆还田后,土壤中可提取态镉的动态变化规律以及对白菜生长和吸收重金属镉的影响。结果表明,秸秆还田显著提高了2种镉污染土壤的pH值。镉污染水稻土上还田玉米和菜豆秸秆显著提高了土壤中醋酸铵提取态镉和DTPA提取态镉含量,秸秆还田后2周时醋酸铵提取态镉含量增加了17%~33%,随时间延长,土壤中可提取态镉增加变的不明显。模拟镉污染土壤上还田玉米和菜豆秸秆对土壤中醋酸铵提取态镉和DTPA提取态镉含量影响不明显。镉污染水稻土上秸秆还田量2%时显著降低了白菜体内镉含量,还田菜豆秸秆和玉米秸秆白菜体内镉含量分别降低了18%和27%。还田玉米秸秆影响了白菜生长,降低了白菜的产量;模拟镉污染土壤上还田菜豆秸秆对白菜生长和镉含量影响不明显,但还田2%玉米秸秆降低了白菜生物量,增加了白菜镉含量。

Effects of Crop Straw Return on Soil Cadmium Availability in Different Cadmium Contaminated Soil

Pot experiments and soil incubation experiments were conducted under greenhouse conditions to investigate the effects of crop straw return on Cd uptake by chinese cabbage and dynamics of Cd availability in Cd-contaminated soil and artificial Cd-contaminated soil.The results showed that soil pH increased significantly in the Cd-contaminated soil and artificial Cd-contaminated soil with maize and kid-ney bean straw return.Crop straw returning significantly increased the concentrations of NH4OAc and DTPA extractable Cd in the Cd-con-taminated soil,concentration of NH4OAc extractable Cd increased by 17%~33% after 2 weeks of straw-returning.Whereas in the artificial Cd-contaminated soil,there was no significant difference in the concentrations of NH4OAc and DTPA extractable Cd between soils with and without crop straw return.The Cd concentration of chinese cabbage was decreased by 18%~27% with 2% crop straw return in the Cd-con-taminated soil.However,the crop straw-returning did not lower the Cd concentration of chinese cabbage in artificial Cd-contaminated soil.Maize straw returning also decreased the shoot dry weight of chinese cabbage significantly on the two Cd-contaminated soils.