Biochar-based fertilizer enhanced Cd immobilization and soil quality in soil-rice system

Abstract Cadmium (Cd) contamination poses a serious problem in paddy soils because of its high health risk through soil-food chain transfer. To evaluate the effect of biochar-based fertilizer on Cd uptake, soil and rice quality, biochar amendment at rates from 0 to 15 t/hm2 was conducted in Cd polluted paddy soils. For successive two rice seasons, biochar treatments greatly reduced rice Cd and soil bioavailable Cd content. Furthermore, the concentration of bioavailable Cd decreased accordingly with the increase of biochar content. When soil properties, such as pH and soil organic carbon (SOC) were significantly improved, grow indexes of rice, especially for the late rice, would be partly improved. Most of the bioavailable Cd was immobilized in root, only a small partition of Cd was transferred to brown rice. The main stage for Cd accumulation was from heading stage to harvest stage.