不同施用量石灰和生物炭对稻田镉污染钝化的延续效应

为筛选适用于西南地区稻田土壤及农作物Cd污染的修复技术,采用田间小区试验比较了单施石灰、生物炭以及复合施用石灰+生物炭及其不同用量对Cd污染稻田的土壤基本理化性质、稻米Cd含量及其水稻各部位富集转运的影响。结果表明:第1年修复试验中,单施石灰和生物炭以及复合施用均可降低稻米Cd含量以及水稻各部位富集和转运系数,且随着施加量的增加稻米Cd含量呈降低趋势,土壤至水稻根系Cd富集系数呈先降低后增加趋势,复合施用(石灰(1.5 t/hm^2)+生物炭)效果优于单施石灰和生物炭,与对照相比,稻米Cd含量降低57.14%~88.57%,土壤至水稻根系富集系数降低22.06%~32.96%;施用石灰可显著提高土壤pH和降低土壤有效态Cd含量。第2年修复剂施用延续效应试验中,石灰在短时间内降低土壤有效Cd和稻米Cd的效果较好,但其长效性和稳定性不及生物炭,与对照相比,单施石灰和生物炭以及复合施用土壤有效Cd分别降低2.97%~25.19%,13.94%~23.41%,1.93%~21.41%,稻米Cd含量分别降低0.72%~34.87%,12.11%~49.14%,36.55%~51.71%。总体来看,设定试验条件下,复合施用(石灰(1.5 t/hm^2)+生物炭(3.0 t/hm^2)),效果最优。

Continuous Effect of Different Application Rates of Lime and Biochar on the Passivation of Cadmium Pollution in Paddy Fields

In order to screen the remediation technology suitable for Cd pollution of paddy soil and crops in Southwest China, a field experiment was used to compare the effects of single application of lime, biochar, combined application of lime + biochar and their different amounts on the basic physical and chemical properties of Cd contaminated paddy soil, the Cd content and its influence on the enrichment and transportation of various parts of rice. The results showed that single application of lime and biochar as well as combined application can reduce the Cd in rice and the enrichment and transport coefficients of various parts of rice in the first year of restoration test. With the increase of the applied amount, the Cd content of rice showed a decreasing trend, and the Cd enrichment coefficient of soil to rice root system first decreased and then increased. Compound application (lime (1.5 t/hm²) + Biochar) was more effective than single application of lime and biochar. Compared with the control, the Cd content of rice treated with combined application (lime (1.5 t/hm²) + Biochar) reduced by 57.14% ~ 88.57%, and the enrichment coefficient of soil to rice root system reduced by 22.06% ~ 32.96%. The application of lime could significantly increase soil pH and reduce the soil available Cd content. In the second year of the remediation agent application continuation effect test, the effect of lime in reducing soil effective Cd and rice Cd in a short period of time was better, but its long-term effect and stability were not as good as biochar. Compared with the control, the effective Cd of soil treated with single application of lime, biochar and combined application reduced by 2.97% ~ 25.19%, 13.94% ~ 23.41%, and 1.93% ~ 21.41%, respectively, and the Cd content of rice reduced by 0.72% ~ 34.87%, 12.11% ~ 49.14%, and 36.55% ~ 51.71%, respectively. Overall, under the experimental conditions, the combined application (lime (1.5 t/hm²) + biochar (3.0 t/hm²) had the best effect.