The Reduction Effect Research Of Cd Amendments On Tobacco

The in-situ immobilization of heavy metal contamination soil is a problem which needsurgent solution. The article discussed the effect of different amendments on Cd concentration insoil and reduction rate in tobacco leaves under production conditions by designing fieldexperiments of red mud, rape straw, lime and dolomite which are prevalent amendments currently.By comparing the results, we acknowledged that red mud and rape straw were more efficient.Then we designed application treatments of different amount of red mud and rape straw in highCd concentration soil, middle Cd concentration soil and low Cd concentration soil respectively, inorder to research the reasonable and efficient proportion of amendments and provide theoreticalfoundation of amendments practical application. The main results are as follows:(1) Red mud, lime and dolomite can increase soil pH all significantly, but rape strawincreased soil pH non-significantly. With the increase of red mud, lime and dolomite, the availableCd content decreased significantly. In the red mud experiment, the treatment of500kg/666.7m~2red mud was most efficient which decreased the available Cd content35.42%relatively comparedwith control. In lime experiment, the treatment of200kg/666.7m~2lime was most efficient whichdecreased the available Cd content20.83%relatively compared with control. In dolomiteexperiment, the treatment of200kg/666.7m~2dolomite was most efficient which decreased theavailable Cd content15.28%relatively compared with control.(2) In red mud and rape straw experiments, available Cd content in soil and Cd content intobacco leaves were significantly pos itive correlation. In the red mud experiment, the treatment of300kg/666.7m~2red mud was most efficient which decreased the Cd content37.69%in maturetobacco leaves relatively compared with control, and decreased the Cd content15.81%influe-cured tobacco leaves relatively compared with control. In the rape straw experiment, thetreatment of300kg/666.7m~2red mud was most efficient which decreased the Cd content15.73%in mature tobacco leaves relatively compared with control, and decreased the Cd content14.06%in flue-cured tobacco leaves relatively compared with control.(3) In the red mud and rape straw combination experiment, there were different results ineach Cd content soil.500kg/666.7m~2red mud plus200kg/666.7m~2rape straw treatment wasmost efficient which decreased the Cd content39.44%in flue-cured tobacco leaves relativelycompared with control in high Cd content soil.300kg/666.7m~2red mud plus100kg/666.7m~2rape straw treatment was most efficient which decreased the Cd content42.20%in flue-curedtobacco leaves relatively compared with control in middle Cd content soil.200kg/666.7m~2redmud plus200kg/666.7m~2rape straw treatment was most efficient which decreased the Cd content29.73%in flue-cured tobacco leaves relatively compared with control in middle Cd content soil.The long term experiment in high Cd content soil indicated that,500kg/666.7m~2red mud plus200kg/666.7m~2rape straw treatment had sustaining reduction effect in the second year. Theamendments decreased the Cd content43.98%in mature tobacco leaves relatively, and it had noharm to the tobacco. The reduction effect of amendments combination was better than single amendment.As the result above indicated, amendments combination decreased Cd content in tobaccoleaves by decreasing the availability of Cd in soil.500kg/666.7m~2red mud plus200kg/666.7m~2rape straw treatment was most efficient in high Cd content soil.300kg/666.7m~2red mud plus100kg/666.7m~2rape straw treatment was most efficient in middle Cd content soil.200kg/666.7m~2red mud plus200kg/666.7m~2rape straw treatment was most efficient in low Cd content soil.Therefore, choosing scientific amendment applications in different soil type and Cd content, wecould decrease soil available Cd content and tobacco Cd content efficiently.