In situ phytostabilization of arable soils severely contaminated with cadmium at Yangshuo, Southern China, using cash crops and amendments: a comprehensive performance evaluation

Purpose Phytostabilization is known to be a promising technique to prevent the off-site movement of cadmium (Cd) from severely contaminated arable soils. Previous studies have recognized plants and amendments that could be potentially used for phytostabilization, such as non-edible fiber and energy crops and biochar. However, there is a paucity of information on the performance of these candidate crops and amendments for the application in the field. Methods Twelve plant-amendment systems were established on the farmland severely contaminated with Cd in the South China karst area, which comprises cash crops kenaf ( Hibiscus cannabinus ), ramie ( Boehmeria nivea ), and sorghum ( Sorghum bicolor ) together with the application of lime, coconut shell biochar, and rice straw biochar at different rates. A comprehensive score was introduced to evaluate the performance of the studied plant-amendment systems, considering not only the indicators related to soil Cd mobility but also the costs. Results After one crop cycle, a 40% median rate of reduction was achieved in soil available Cd. An intensive application of biochar lowered the comprehensive performance since a significantly increased cost gained only a slight improvement in the reduction of soil available Cd. Sorghum with 0.5% ( w / w ) rice straw biochar showed the best performance in the study site, which effectively sequestrated Cd in the roots and reduced soil available Cd at a relatively low cost. Conclusion This work shows the performance and the comprehensive evaluation of candidate plant-amendment systems for the in situ phytostabilization.