Effects of soil amendments applied on cadmium availability, soil enzyme activity, and plant uptake in contaminated purple soil

Soil Cd pollution resulting from human activities has become a serious food safety concern. This study was to investigate the impacts of eight soil amendments including a humic acid material (XZ), three organic-inorganic combined materials (FY, PX and PLY) and four inorganic materials (FS, LIME, PLL and PL) on soil Cd availability, enzyme activity, and the uptake by vegetables under incubation, greenhouse and field conditions. Results showed that soil exchangeable Cd (EX-Cd) concentrations under four amendments (FY, XZ, PX, FS) significantly decreased by 12.10–13.59% after 20d treatments, and both PX and PLY resulted in reduced soil EX-Cd fraction while increased fractions of Fe-Mn oxides (OX-Cd), organic matter (OM-Cd) and residual (Res-Cd) in the Cd-contaminated purple soil. PX significantly reduced soil EX-Cd and carbonate-bound (CB-Cd) fractions by 4.4% and 11.4%, and decreased vegetable Cd uptake by 38.8% and 49.1% in greenhouse and field experiments, respectively. Moreover, PX elevated the activities of soil catalase, urease and saccharase by 15.7%, 53.6% and 48.2% in pot soil, which were ~4, ~5 and ~14 times higher those in field soil, respectively. This research demonstrated that PX could be an effective soil amendment to reduce the Cd health and ecological riskthe 1s in the Cd-contaminated purple soil.