施用生物炭对土壤Cd形态转化及烤烟吸收Cd的影响

采用盆栽试验模拟Cd污染土壤,研究施用烟秆炭(0、10、20 g·kg~(-1))对土壤pH、有机质含量、土壤Cd形态分布及烤烟Cd含量和Cd累积量的影响.结果表明:随着生育期的延长,土壤pH和有机质含量均呈现升高的趋势.在同一Cd污染水平下,土壤pH和有机质含量均随生物炭施用量的增加而升高.随生物炭施用量的增加,土壤有效态Cd和可交换态Cd含量显著降低,土壤碳酸盐结合态Cd、铁锰氧化物结合态Cd、有机结合态Cd和残渣态Cd含量升高.移栽后30 d,处理G2T2和G2T1的土壤有效态Cd含量的降幅分别达到45.59%和24.56%.外源添加Cd的土壤中,土壤pH和有机质含量均与土壤有效态Cd和可交换态Cd含量呈显著负相关关系(p0.01),与土壤碳酸盐结合态Cd、铁锰氧化物结合态Cd和有机结合态Cd含量呈显著正相关关系(p0.01).在Cd污染土壤上,施用生物炭能明显降低烟株各部位Cd含量,烟株各部位干物质积累量随生物炭施用量的增加显著升高,烟株各部位Cd累积量和总Cd累积量随生物炭施用量的增加呈降低的趋势.由此说明,在Cd污染的土壤上施用生物炭能够使土壤中可被植物吸收利用的有效态Cd转化为潜在的无效态Cd,从而达到修复土壤并减轻作物受Cd毒害的目的.

Effects of biochar addition on the soil Cd fraction and the absorption of Cd by tobacco

A pot experiment was carried out to study the effects of biochar addition (0, 10, 20 g·kg^-1) on soil pH, organic matter content, soil Cd fraction, the Cd concentrations and accumulation in tobacco plants in the Cd polluted soil. The results demonstrated that soil pH and organic matter content showed an increasing trend as the growing season progressed. Soil pH and organic matter content increased with the increase of biochar rate under the same biochar rate. With the increase of biochar rate, soil available Cd content and exchangeable Cd content decreased significantly, whereas the soil carbonate bound Cd content, Fe-Mn oxide bound Cd content, organic bound Cd content and residual Cd content showed an opposite trend. The soil available Cd contents in the G2T2 and G2T1 treatments decreased by 45.59% and 24.56%, respectively, at 30 d after transplanting. In the Cd polluted soil, both the soil pH and organic matter content presented a significantly negative correlation with the soil available Cd content and the exchangeable Cd content. However, the soil pH and organic matter content were significantly and positively correlated with soil carbonate bound Cd, Fe-Mn oxide bound Cd and organic-bound Cd. In the Cd contaminated soil, application of biochar significantly reduced the Cd content in different parts of tobacco plants. The dry matter accumulation in each part of tobacco plants increased markedly with the increase of biochar rate, and the Cd accumulation in different parts of tobacco plants and the total Cd accumulation decreased with the increase of biochar rate. The application of biochar in Cd contaminated soil can transform the available Cd forms into unavailable forms, which is beneficial to restore the soil and reduce the toxicity of Cd to crops.