Stabilization of cadmium in a fluvo-aquic soil-Chinese chive system using loess and chicken manure compost

The stabilization of heavy metals in soil has been increasingly applied in China in recent years due to its quick effect and low cost. In this study, loess and chicken manure compost (a commercial organic fertilizer) were used to stabilize Cd in slightly polluted fluvo-aquic soil from the North China Plain, and the driving factors for stabilization were investigated through ridge regression. The additives significantly reduced the total concentration of Cd in soil through dilution. The addition of loess and compost increased carbonates and organic matter in soil, respectively. This caused exchangeable Cd to be transformed to fractions bound to carbonates or organic matter, thereby decreasing the concentration of Cd in the roots and leaves of Chinese chive. The decreasing exchangeable Cd in soil was the direct cause of decreased uptake of Cd by plants, and the increasing fractions bound to carbonates or organic matter were indirect influencing factors. However, adding loess decreased soil fertility and retarded plant growth. The addition of compost compensated for these defects. This study suggests that the combined addition of loess and chicken manure compost was able to effectively reduce the total concentration and phytoavailability of Cd in soil and guarantee crop yield and quality.