Soil pollution with cadmium (Cd) has been threatening the human health. In this study, we investigated the possibility of applying biochar and oyster shell to reduce Cd uptake by crops and modify soil quality. A field study based on the rice–oilseed rape rotation was done, and the treatments were comprised without amendments (PA0) and with 15 000 kg ha⁻¹ biochar (PA1), 15 000 kg ha⁻¹ oyster shell (PA2), and 7500 kg ha⁻¹ biochar and 7500 kg ha⁻¹ oyster shell (PA3). Results revealed that both oyster shell and biochar reduced the HOAc-extractable Cd in soil. Compared to PA0, the HOAc-extractable Cd in the PA1, PA2, and PA3 treatments was reduced by 4.76 %–20.79 %, 17.86 %–38.61 %, and 5.95 %–10.89 %, respectively. The cooperative application of biochar and oyster shell reduced the Cd accumulation in brown rice and oilseed by 29.67 % and 19.74 %, respectively, compared to control and thus decreased the hazard quotient (HQ) from the consumption of brown rice and oilseed. The addition of biochar slightly increased soil organic matter. In addition, the available P in the PA2 and PA3 treatments was significantly (p<0.05) increased by 200.96 %–295.92 % and 187.46 %–280.04 % compared to the control. Moreover, the cooperative application of biochar and oyster shell enhanced the activities of urease, catalase, and β-galactosidase by 139.44 %–147.56 %, 10.71 %–34.31 %, and 82.08 %–244.38 %, respectively. These results demonstrated that the utilization of biochar and oyster shell might be an effective pathway to reducing Cd uptake by crops and improving soil fertility and enzyme activities.

中文翻译：

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生物炭和牡蛎壳的应用减少了作物对镉的吸收，并改善了土壤肥力和受污染土壤中的酶活性

土壤中的镉（Cd）污染一直威胁着人类健康。在这项研究中，我们调查了应用生物炭和牡蛎壳来减少作物对 Cd 的吸收并改变土壤质量的可能性。进行了一项基于水稻-油菜轮作的田间研究，处理包括无改良剂 (PA0) 和 15 000 kg ha ^-1生物炭 (PA1)、15 000 kg ha ^-1牡蛎壳 (PA2) 和7500 kg ha ^-1生物炭和 7500 kg ha ^-1牡蛎壳（PA3）。结果表明，牡蛎壳和生物炭都降低了土壤中的 HOAc 可萃取 Cd。与 PA0 相比，PA1、PA2 和 PA3 处理中的 HOAc 可萃取 Cd 分别降低了 4.76 %–20.79 %、17.86 %–38.61 % 和 5.95 %–10.89 %。与对照相比，生物炭和牡蛎壳的协同施用使糙米和油籽中的镉积累分别降低了 29.67 % 和 19.74 %，从而降低了食用糙米和油籽的危害商 (HQ)。添加生物炭略微增加了土壤有机质。此外，PA2 和 PA3 处理的有效 P 显着（p < 0.05) 与对照相比分别增加了 200.96 %–295.92 % 和 187.46 %–280.04 %。此外，生物炭与牡蛎壳的协同应用使脲酶、过氧化氢酶和β-半乳糖苷酶的活性分别提高了139.44%~147.56%、10.71%~34.31%和82.08%~244.38%。这些结果表明，生物炭和牡蛎壳的利用可能是减少作物吸收镉、提高土壤肥力和酶活性的有效途径。