Direct and residual impacts of zeolite on the remediation of harmful elements in multiple contaminated soils using cabbage in rotation with corn.

In the present work, in-situ two pot trials were conducted to explore the direct and residual influences of zeolite (ZL) on plant height, dry biomass and bioavailability of Pb, Cd, Cu, and Zn by growing cabbage followed by corn in goldmine-contaminated (GM-C), smelter factory-contaminated (SF-C), and farmland-contaminated (FL-C) soils. Initially, a single treatment of ZL was applied at 20 t/ha, and cabbage was grown under greenhouse pot conditions. After cabbage harvesting, corn was grown in the same pots without additional application of ZL. The results indicated that ZL as an amendment evidently promoted the cabbage and corn yields, whereas the residual influence of ZL did not promote corn dry matter yield in SF-C and FL-C soils compared to CK. Incorporation of ZL potentially decreased the mobility of Pb, Cd, Cu and Zn in contaminated soils after harvesting cabbage and corn compared with CK. In both crops, the Pb, Cd, Cu and Zn contents in plants root and shoot biomasses were dramatically reduced by the direct and residual impacts of ZL rather than CK. This study highlights that the direct and residual influences of ZL at a 20 t/ha application rate have the possibility to support the reclamation of soils polluted with harmful elements and that, by itself, ZL can promote plant growth and increase the value of field crops. The detailed studied regarding residual influence of ZL for restoration of multi-metal polluted soils would be confirmed at the ex-situ condition.