土壤调理剂对重度镉污染土壤改良及农作物吸收累积镉的影响

Effects of Soil Conditioners on the Improvement of Heavily Cadmium Polluted Soil and the Absorption and Accumulation of Cadmi⁃um by Crops

[目的]研究土壤调理剂对重度镉污染土壤改良及农作物吸收累积镉的影响。[方法]利用恩施富硒高镉地区表层土壤作为盆栽供试土壤,以辣椒为供试作物,通过开展盆栽试验,研究9种土壤调理剂对辣椒生长、吸收积累镉以及土壤中镉形态变化的影响。[结果]土壤调理剂的施用能明显降低辣椒果实中镉含量,降幅76.35%~90.27%,总体以T_(4)土壤调理剂(12.99%小麦秸秆生物炭+6.49%过磷酸钙+64.94%凹凸棒石+2.60%硅肥+12.99%贝壳粉)效果最佳。添加生物炭比菜籽粕试验组提升土壤pH效果更好;土壤调理剂的施用能显著降低可交换态和碳酸盐结合态镉含量,且可以促使镉向农作物不可利用的铁锰结合态以及残渣态转变,同时提高了植物叶片的光合速率,促进了植株的生长。辣椒果实镉含量与土壤中镉相关关系表明,辣椒在吸收土壤中水溶态镉的同时,也会对碳酸盐结合态镉进行吸收。[结论]在恩施富硒高镉地区施用“12.99%小麦秸秆生物炭+6.49%过磷酸钙+64.94%凹凸棒石+2.60%硅肥+12.99%贝壳粉”组合的调理剂可有效降低农作物对镉的吸收。高镉地区进行农作物安全种植不仅要降低能被植物直接利用的水溶态和离子交换态镉活性,还需降低具有潜在风险的碳酸盐结合态镉含量。

[Objective]To study the effects of soil conditioners on the improvement of heavily cadmium contaminated soil and the absorption and accumulation of cadmium by crops.[Method]The surface soil of Enshi area rich in selenium and high cadmium was used as the pot experi⁃ment soil,and pepper was used as the test crop.Through pot experiment,the effects of nine soil conditioners on the growth,absorption and accu⁃mulation of cadmium in pepper,as well as the change of cadmium morphology in soil were studied.[Result]The application of soil conditioners could significantly reduce the content of cadmium in pepper fruits by 76.35%-90.27%,and T_(4)soil conditioner(12.99%wheat straw biochar+6.49%superphosphate+64.94%attapulgite+2.60%silicon fertilizer+12.99%shell powder)had the best effect overall.Compared with rapeseed dregs,biochar in experimental group had a significant effect on soil pH.The application of soil conditioner could significantly reduce the content of exchangeable and carbonate⁃bound cadmium,and promote the conversion of cadmium to the unusable iron⁃manganese binding state and residue state,and increase the photosynthetic rate of plant leaves and promote plant growth.The correlation between the content of cadmium in pepper fruit and cadmium in soil indicated that pepper could absorb both water⁃soluble cadmium and carbonate⁃bound cadmium in soil.[Conclusion]The combination of"12.99%wheat straw biochar+6.49%superphosphate+64.94%attapulgite+2.60%silicon fertilizer+12.99%shell powder"can effectively reduce the uptake of cadmium by crops in selenium⁃rich and cadmium⁃high areas of Enshi.The safe planting of crops in high cadmium area should not only reduce the activities of water⁃soluble and ion⁃exchange cadmium,which can be directly used by plants,but also reduce the content of carbonate⁃bound cadmium,which has potential risks.