Abstract：
Excessive heavy metals in soils can threaten food security and soil health. New practical technology is urgently needed to remediate cadmium (Cd) contaminated paddies in many parts of the world. Chinese milk vetch (M), rice straw (R), and soil amendments can reduce Cd activity in soil; however, the mechanism underlying this reduction is not well understood. This study explored the impact of co-incorporation of milk vetch, rice straw, and either lime (L), sesbania biochar (B), or sepiolite on soil Cd bioavailability through field experiments. The results indicated that the rice grain Cd concentrations in soil treated with milk vetch + rice straw + fertilizer (MRF, 16.6 %), milk vetch + rice straw + fertilizer + sesbania biochar (MRFB, 50.1 %), and milk vetch + rice straw + fertilizer + lime (MRFL, 48.3 %) were significantly lower than those in soil treated with fertilizer (F). The acid-soluble Cd concentrations influenced rice grain Cd uptake and were 33.9 % and 47.5 % lower for the MRFB and MRFL treatments, respectively, than for F alone. A decrease in acid-soluble Cd (AciCd) was accompanied by a decrease in Eh and increases in pH, Fe2+, cation exchange capacity, and dissolved organic carbon. The MRFB treatment promoted iron plaque (IP) formation on the rice root surface. The relative abundances of Desulfobacterota and Verrucomicrobiota were higher for the MRFB treatment than for the other treatments. A partial least squares path model confirmed that Aci-Cd and low-crystalline IP (IP-Feh) influenced the rice grain Cd concentration.
摘要：
土壤中重金属过多可能威胁粮食安全和土壤健康。在世界许多地方，迫切需要新的实用技术来修复镉（Cd）污染的稻田。紫云英(M),稻草(R),土壤改良剂可以降低土壤中的Cd活性；然而，这种减少的潜在机制尚不清楚。本研究探讨了紫云英共掺入的影响，稻草,和石灰(L)，芝麻生物炭(B)，通过田间试验或海泡石对土壤Cd的生物有效性。结果表明，用紫云英+稻草+肥料(MRF，16.6%），紫云英+稻草+肥料+芝麻生物炭(MRFB，50.1%），和鹿茸+稻草+肥料+石灰(MRFL，48.3％）显着低于肥料（F）处理的土壤。酸溶性Cd浓度影响了水稻籽粒Cd的吸收，MRFB和MRFL处理分别降低了33.9％和47.5％，分别,而不是F。酸溶性Cd（AciCd）的减少伴随着Eh的减少和pH的增加，Fe2+,阳离子交换能力，和溶解的有机碳。MRFB处理促进了水稻根表面铁菌斑(IP)的形成。MRFB处理的脱硫细菌和Verrucomicrobiota的相对丰度高于其他处理。偏最小二乘路径模型证实了Aci-Cd和低结晶IP（IP-Feh）对水稻籽粒Cd浓度的影响。
