海泡石施加深度对水稻吸收镉的影响

为探讨海泡石施加深度对镉（Cd）污染土壤钝化修复效果的影响，选取湖南湘潭酸性水稻土，采用根际箱培养的方式，研究海泡石施加深度对土壤中Cd生物有效性、植株Cd吸收和根际环境的影响特征。结果表明，与未添加海泡石的对照相比，海泡石在施加深度为20、10 cm和5 cm的处理下，根际与非根际各层土壤pH值分别提高了1.00~1.16、0.59~1.21个单位，根际与非根际各层土壤中Cd有效态含量分别降低了0.02%~3.40%和1.00%~7.80%，且海泡石施加深度为5 cm（T2）时根际与非根际层土壤Cd有效态含量降幅最大，分别为3.40%和7.80%；海泡石不同施加深度处理水稻各部位Cd含量均有下降，且在施加深度5 cm并隔离根系向未钝化土壤延伸处理（T4）降幅最大，与对照相比根部Cd含量下降显著（P<0.05），同时，海泡石在不同施加深度处理下水稻株高和产量均有提高，且与对照相比海泡石在T2和T4耕层深度处理下株高和产量显著提高（P<0.05）。可见，浅耕（耕层5 cm处理）施用海泡石降低土壤Cd生物有效性效果最好，且降低了水稻中Cd含量，显著提高了水稻产量。

The effect of sepiolite application depth on cadmium uptake from rice

In the acid paddy soil in Xiangtan, Hunan Province, rhizosphere chamber culture experiments were conducted to explore the remediation effects of sepiolite on cadmium(Cd) -contaminated soil using different depth treatments of the cultivated soil. The aim was to investigate the effects of sepiolite application depth on Cd bioavailability in soil, plant Cd absorption, and rhizosphere environment. The results showed that, compared with the control without sepiolite, the pH value of rhizosphere and non-rhizosphere soil increased by 1.00~1.16 and 0.59~1.21 units using treatments at depths of 20, 10, and 5 cm; further, the available Cd content in the rhizosphere and five nonrhizosphere soil layers decreased by 0.02%~3.40% and 1.00%~7.80%, respectively. In addition, when the sepiolite application depth was 5 cm(T2), the available Cd content of the rhizosphere and non-rhizosphere soil showed the largest decreases of 3.40% and 7.80%, respectively. Moreover, the Cd content of each part of the rice decreased after sepiolite treatments were applied at different depths, and the Cd content of each part of the rice had the biggest drop when the sepiolite was applied to the soil at a depth of 5 cm, preventing the root from reaching the unpassivated soil(T4). Furthermore, compared to the control, the Cd content of the root decreased significantly(P<0.05).At the same time, the plant height and yield of rice increased with treatments at different depths; the biggest rise was with treatments of T2 and T4, with significant differences(P<0.05). Overall, it could be seen that the application of sepiolite in shallow tillage(a treatment applied under the 5 cm plow layer) resulted in the best effect in reducing soil Cd bioavailability, and it also reduced the Cd content in rice and significantly increased rice yield.