Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.
Ecotoxicol Environ Saf. 2021 Oct 15;223:112621. doi: 10.1016/j.ecoenv.2021.112621. Epub 2021 Aug 11.
Increasing cadmium (Cd) contamination in agricultural fields has resulted in a higher risk of Cd accumulation in the food chain. Lime addition can mitigate soil acidification and reduce Cd accumulation in crops cultured in Cd-contaminated soil. To determine key factors controlling the outcomes of liming in reducing Cd accumulation and enhancing soil pH, we performed a meta-analysis using previously published data from field and pot experiments. The results indicated that the liming showed positive effect sizes on the soil pH but negative effect sizes on Cd accumulation in crops, indicating the addition of different lime materials could enhance soil pH and reduce Cd accumulation in crops. The effect sizes of liming on soil pH under pot experimental conditions were higher than that under field experimental conditions, however, the effect sizes of application types and amount of limes on soil pH did not significantly differ between their individual different levels. Under a low background value of soil pH, SOM, CEC and clay, the addition of limes showed a significantly higher effect size on soil pH when compared to their individual higher soil background value, suggesting that the lower background values of soil pH, SOM, CEC and clay might facilitate the outcomes of liming to enhance soil pH. The experiment patterns, crop types and lime application amounts showed a limit effect on the outcomes of liming to reduce the shoot and grain Cd concentrations in crops. The lime types only showed a significant effect size on the shoot Cd accumulation but not on the grain Cd accumulation, in which the CaCO had the highest effect size (absolute value, the same below) followed by Ca(OH) and CaO. The low soil background values of total Cd concentration and CEC content, but a high soil SOM background content might facilitate the outcomes of liming to reduce the shoot Cd concentration in crops. However, only the background value of soil clay content showed a significantly negative effect size on the grain Cd accumulation, where a high soil clay content had a higher effect size than a low soil clay content. These findings provide useful knowledge about the effects of experiment patterns, crop types, soil conditions, lime types and lime addition amounts on the efficiency of liming in enhancing soil pH and decrease crop Cd concentration.
农田中镉（Cd）污染的增加导致食物链中 Cd 积累的风险增加。石灰的添加可以减轻土壤酸化，并减少 Cd 污染土壤中作物的积累。为了确定控制石灰在降低 Cd 积累和提高土壤 pH 值方面的结果的关键因素，我们使用先前发表的田间和盆栽实验数据进行了荟萃分析。结果表明，石灰对土壤 pH 值有积极的效应大小，但对作物中 Cd 积累有负效应大小，表明添加不同的石灰材料可以提高土壤 pH 值并降低作物中 Cd 的积累。盆栽实验条件下石灰对土壤 pH 值的效应大小高于田间实验条件下的效应大小，然而，石灰应用类型和用量对土壤 pH 值的效应大小在各自不同水平之间没有显著差异。在土壤 pH 值、有机质（SOM）、阳离子交换量（CEC）和粘土含量的背景值较低的情况下，石灰的添加对土壤 pH 值的影响较大，与各自较高的土壤背景值相比，这表明土壤 pH 值、SOM、CEC 和粘土的较低背景值可能有利于石灰提高土壤 pH 值的结果。实验模式、作物类型和石灰施用量对石灰降低作物地上部和籽粒 Cd 浓度的结果表现出限制效应。石灰类型仅对地上部 Cd 积累有显著的效应大小，而对籽粒 Cd 积累没有显著的效应大小，其中碳酸钙（CaCO）的效应大小最高（绝对值，下同），其次是氢氧化钙（Ca(OH)）和氧化钙（CaO）。土壤全 Cd 浓度和 CEC 含量的低背景值，但高土壤 SOM 背景含量可能有利于石灰降低作物地上部 Cd 浓度的结果。然而，只有土壤粘粒含量的背景值对籽粒 Cd 积累有显著的负效应大小，其中高土壤粘粒含量的效应大小高于低土壤粘粒含量。这些发现为实验模式、作物类型、土壤条件、石灰类型和石灰施用量对石灰提高土壤 pH 值和降低作物 Cd 浓度效率的影响提供了有用的知识。
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