[Remediation of Cadmium Contaminated Paddy Fields Using Soil Conditioners]

Four soil conditioners, SAMMNS, CCT01, Mineral, and Tebeigai were selected for this study. The effects of the four conditioners on soil pH, bulk density, organic matter, available nutrients, texture, microaggregates, Cd available in soil, and Cd content in brown rice were investigated using field-controlled cadmium tests conducted in cadmium-contaminated paddy fields in Pingxiang. The results showed that compared to the control, soil conditioners could increase pH, bulk density, and cation exchange capacity in soil. SAMMNS and CCT01 soil conditioners increased the amount of silt and clay, but that of sand decreased, whereas the Mineral and Tebeigai soil conditioners decreased silt and clay, and sand increased. In addition to the CCT01 soil conditioner, the application of soil conditioners increased large-scale agglomerates and reduced small-scale microaggregates. The effects of soil conditioners on soil physical and chemical properties promoted the conversion of Cd from contaminated soil from high activity to low activity, which reduced available Cd content in soil (5.21%-34.78%) and Cd content in brown rice (51.39%-68.06%). Correlation analysis showed that Cd content in brown rice was significantly positively correlated with available Cd and available phosphorus in soil, whereas it was negatively correlated with pH and bulk density in soil. Considering the effects of soil and brown rice on cadmium reduction and physicochemical properties, Tebeigai soil conditioner exhibited the best repair effects, followed by SENMES and Mineral soil conditioner.