绿肥作物矿化分解对土壤镉有效性的影响研究进展

Research advance on the effect of mineralization and decomposition of green manure crops on soil cadmium availability

绿肥是一种生物有机肥,其矿化分解是绿肥作物翻压进入土壤中被微生物分解产生植物可直接利用的物质的过程。绿肥矿化分解可影响土壤镉(Cd)有效性,但绿肥与Cd有效性两者并非简单的线性相关。本文综述分析了绿肥作物矿化分解对土壤Cd有效性的影响及其作用机理。结果表明:在绿肥翻压进入土壤被微生物分解的过程中,土壤中的可溶性有机质、pH值与Eh值、铁还原和微生物群落均影响重金属Cd在土壤中的迁移,可以使重金属Cd固定在土壤中或在植物根系表面沉淀;作物细胞拦截可降低Cd向地上部分的转运,最终只有极少量Cd到达作物的可食用部分。但由于受到绿肥用量、作物品种、土壤理化性状等其他因素的干扰,绿肥对土壤中Cd的修复效果具有不确定性。最后,通过总结分析绿肥对土壤性质的影响和其他因素对绿肥的干扰,阐明了绿肥对土壤中Cd有效性的影响机制。

Green manure is a kind of bio-organic fertilizer,and its process of mineralization and decomposition produces substances that plants can directly use and affect the soil Cd availability upon decomposition by microorganisms in the soil.Green manures have different effects on Cd availability;however,there is no simple linear relationship between them.In this study,the effect of dissolved organic matter,pH and Eh,iron reduction,and microbial communities on Cd availability and accumulation in green manure crops were reviewed.Results showed that upon application of green manure decomposed by microorganisms in soil,the soil dissolved organic matter,pH and Eh,iron reduction and microbial communities influenced the migration of Cd(soil heavy metal),which could be immobilized in the soil or precipitated on the ground of plant roots.Above-ground part of Cd decreased after many interceptions by miscellaneous cells,and only a very small amount of Cd finally reached the edible part of crop.However,there was an uncertain effect of green manure on soil Cd repaired,which was disturbed by other factors such as green manure dosage,crop varieties,and soil physical and chemical properties.In this study,we investigated the effect of green manure on different soil conditions,and green manure was disturbed by other factors in clarifying the mechanism of its effect on Cd availability.