This study focused on the effects of biochar (BC) application on soil chemical properties and mobilization of cadmium (Cd) and lead (Pb) in the paddy soil. BC was applied at the rate of 0, 10, 20 and 40 t ha⁻¹, respectively. BC application caused a significant increase in soil organic carbon contents (SOC), pH, nitrate–nitrogen (‐N),and available phosphorus contents (AP) in the top and subsurface soil, while SOC contents in the subsurface soil decreased with increasing rate of BC. BC40 effectively reduced the mobility of Cd and Pb from the top layer to the subsurface soil, while concentrations of Cd and Pb in the topsoil remained unchanged. Path analysis showed that the direct path coefficient AP was highest; SOC, ‐N and AP had a negative direct effect on the Cd and Pb in subsurface soil. Soil pH and ‐N had a high negative indirect effect through AP. The decision coefficient decreased in the following order: pH, AP, SOC, ‐N and ‐N. Regression analysis showed that soil Cd and Pb had a significant linear correlation with soil AP, whereas soil Pb also had a significant linear correlation with soil pH. In conclusion, BC40 can alter soil chemical properties and reduce the mobility of Cd and Pb from the top layer to the lower subsurface of the paddy soil.

中文翻译：

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生物炭对稻田土壤化学性质和镉（Cd）和铅（Pb）迁移的影响

这项研究的重点是生物炭（BC）施用对稻田土壤化学特性的影响以及镉（Cd）和铅（Pb）的迁移。BC分别以0、10、20和40 t ha ^-1的速率施用。施用BC会导致表层和表层土壤的有机碳含量（SOC），pH，硝酸盐-氮（-N）和有效磷含量（AP）显着增加，而表层土壤的SOC含量则随着速率的增加而降低公元前。BC40有效降低了Cd和Pb从顶层到地下土壤的迁移率，而表层土壤中Cd和Pb的浓度保持不变。路径分析表明，直接路径系数AP最高。SOC，‐N和AP对地下土壤中的Cd和Pb具有负面的直接影响。通过AP，土壤pH和‐N具有很高的负面间接影响。决策系数按以下顺序减小：pH，AP，SOC，‐N和‐N。回归分析表明，土壤Cd和Pb与土壤AP呈显着线性相关，而土壤Pb与土壤pH也呈显着线性相关。总之，BC40可以改变土壤化学性质，并降低Cd和Pb从水稻土顶层到下层地下的迁移率。