Combined Application of Biochar and Calcium Superphosphate Can Effectively Immobilize Cadmium and Reduce Its Uptake by Cabbage
2024
Xinlei Peng | Md. Shoffikul Islam | Qian Li | Qingling Fu | Jun Zhu | Hongqing Hu
Biochar and phosphate fertilizer are commonly employed for the mitigation of soil cadmium (Cd) contamination. Nevertheless, there is a dearth of research regarding the mechanism behind their joint implementation. In this study, a combination of corn straw biochar (0 (C<sub>0</sub>), 5 (C<sub>5</sub>), and 10 (C<sub>10</sub>) g kg<sup>−1</sup>) and calcium superphosphate (0 (P<sub>0</sub>), 0.1 (P<sub>1</sub>), 0.2 (P<sub>2</sub>), 0.5 (P<sub>5</sub>), and 1.0 (P<sub>10</sub>) g kg<sup>−1</sup>) was applied in pot experiments, and the effects of the combined application on Cd bioavailability and its uptake by cabbage were investigated in Cd-contaminated soils. The results demonstrated that the combined treatment of applying biochar and Ca(H<sub>2</sub>PO<sub>2</sub>)<sub>2</sub> yielded a significant decrease in the uptake of Cd by cabbage in alkaline soil, in contrast to the individual treatments of biochar or Ca(H<sub>2</sub>PO<sub>2</sub>)<sub>2</sub>. Compared to the CK treatment (C<sub>0</sub>P<sub>0</sub>), the Cd content in the shoots decreased by 46.26% and in the roots decreased by 24.81%, while the biomass of the cabbage demonstrated a noteworthy increase in C<sub>5</sub>P<sub>10</sub> treatment. Compared to the CK treatment, the content of available phosphate (AP) in the soil increased by 17.57 mg kg<sup>−1</sup>, residual Cd increased by 22.02%, the exchangeable Cd decreased by 45.86%, and carbonate-bound Cd decreased by 20.55% in the C<sub>5</sub>P<sub>10</sub> treatment. Therefore, it is advisable to use a combination of 5 g kg<sup>−1</sup> biochar and 1 g kg<sup>−1</sup> Ca(H<sub>2</sub>PO<sub>2</sub>)<sub>2</sub> for the restoration of soil contaminated with Cd.
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