State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Soil and Fertilizer & Resources and Environment Institute, Jiangxi Academy of Agricultural Sciences, Nanchang 330200, China.
Chemosphere. 2024 Sep;363:142784. doi: 10.1016/j.chemosphere.2024.142784. Epub 2024 Jul 5.
Cadmium (Cd) in paddy soil poses significant risks to humans due to its strong biological migration and toxicity. Chinese milk vetch (MV) is commonly used as green manure in the paddy fields of southern China and its potential to decrease the availability of Cd has been identified. Nevertheless, the effects of MV combined with lime materials (lime, L; limestone, LS) on Cd availability, soil properties, enzyme activity and comprehensive benefits are still not fully understood in double-cropping rice system. A field study was conducted to investigate these changes. The results indicated that all treatments notably decreased soil available Cd (Avail-Cd) by 19.3-44.3% and 14.9-43.1% during early and late rice, compared with CK. Moreover, the Cd fractions transformed to more stable forms. Compared to CK, all treatments reduced brown rice Cd content by 34.6-64.2% and 12.7-52.5% during the two periods. Furthermore, the translocation factors root to shoot, as well as shoot to brown rice, decreased. The combination led to improvements in soil properties, soil enzyme activity. Meantime, Cd in iron-manganese plaque (IMP) decreased by 31.9-51.1% and 29.0-42.7% respectively during two periods in amendments treatments. Soil pH and DOC were more important factors for Cd bioavailability than other properties. Additionally, rice Cd uptake was positively correlated with Cd in IMP. Enzyme activity exhibited a negative correlation with soil active Cd. Partial Least Squares Path Model (PLS-PM) indicated that the mitigation of Cd pollution helped to improve soil enzyme activity. Grey correlation analysis (GRA) indicated that MVLS showed the best comprehensive benefits in soil-plant system. Overall, the combination of MV and lime materials could reduce Cd availability, enhance soil properties and enzyme activity. And this could be strengthened by the combination. These findings will provide valuable insights for Cd-contaminated soil remediation.
镉（Cd）在稻田土壤中具有很强的生物迁移性和毒性，对人类构成重大风险。紫云英（MV）通常被用作中国南方稻田的绿肥，其降低 Cd 有效性的潜力已得到确定。然而，在双季稻系统中，紫云英与石灰材料（石灰，L；石灰石，LS）结合对 Cd 有效性、土壤性质、酶活性和综合效益的影响仍不完全清楚。进行了一项田间研究来调查这些变化。结果表明，与 CK 相比，所有处理在早稻和晚稻中均显著降低了 19.3-44.3%和 14.9-43.1%的土壤有效镉（Avail-Cd），而且 Cd 形态向更稳定的形态转化。与 CK 相比，所有处理在两个时期均降低了糙米 Cd 含量 34.6-64.2%和 12.7-52.5%。此外，根到茎和茎到糙米的迁移因子均降低。组合处理改善了土壤性质和土壤酶活性。同时，改良处理中 IMP 中的 Cd 分别减少了 31.9-51.1%和 29.0-42.7%。在两个时期，土壤 pH 和 DOC 对 Cd 生物有效性的影响比其他性质更为重要。此外，水稻对 Cd 的吸收与 IMP 中的 Cd 呈正相关。酶活性与土壤有效 Cd 呈负相关。偏最小二乘路径模型（PLS-PM）表明，减轻 Cd 污染有助于提高土壤酶活性。灰色关联分析（GRA）表明，MVLS 在土壤-植物系统中具有最佳的综合效益。总体而言，紫云英与石灰材料的结合可以降低 Cd 有效性，增强土壤性质和酶活性，并且这种效果可以通过结合得到加强。这些发现为 Cd 污染土壤修复提供了有价值的见解。
