施用钾肥对稻田土镉污染钝化修复效应影响研究

【目的】在Cd污染农田钝化修复中科学、合理施用钾肥。【方法】采用盆栽试验的方法种植水稻,研究了施用不同量氯化钾和硫酸钾对Cd污染稻田土海泡石钝化修复效应的影响。钾肥分别为氯化钾和硫酸钾,试验中施用的氯化钾和硫酸钾分别设置高、中和低3个添加量,钝化剂为海泡石。【结果】海泡石(S)钝化修复可以增加糙米生物量,施用低量(K1L)、中量(K1M)和高量(K1H)KCl后水稻糙米生物量分别降低7.35%、11.47%和4.66%,但与CK相比无显著差异。施用低量硫酸钾(K2L)可使糙米生物量提高2.69%,施用中量硫酸钾(K2M)可使糙米生物量降低1.10%,但与CK无显著性差异,而施用高量硫酸钾(K2H)可使糙米生物量降低14.97%,且与CK差异显著。在Cd污染水稻土钝化修复下,土壤中Cd有效性随KCl施用量的增加而显著增加,与S处理相比增加幅度可达41.67%～58.33%,施用K_2SO_4同样可以增加土壤中有效态Cd质量分数,增加幅度为16.67%～33.33%,但相比KCl对土壤钝化的活化作用要弱。与S处理相比,SK1L、SK1M和SK1H处理可使糙米Cd质量分数分别增加53.38%、46.15%和200.00%;SK2L、SK2M和SK2H处理可使糙米Cd质量分数分别增加7.69%、38.46%和23.08%。在海泡石钝化修复下,KCl对水稻吸收累积土壤Cd的促进作用比K_2SO_4显著得多。【结论】在Cd污染水稻土钝化处理下,土壤中Cd有效性随KCl施用量升高而显著增加,施用KCl对水稻糙米Cd吸收累积具有明显的促进作用,特别是在施用高量KCl时,但施用低量K_2SO_4可以降低水稻根部的Cd累积量,对水稻糙米Cd吸收累积无明显影响,在施用中高量K_2SO_4时,虽然可以在一定程度上促进水稻根系对土壤中有效态Cd的吸收,但与KCl相比效果低很多。

Potassium Fertilizer Enhances the Mobility of Cadmium in Paddy Soil Amended with Sepiolite

【Objective】The mobility of heavy metals in soil is modulated by various chemical and biochemical processes and this paper aims to elicit the efficacy of potassium fertilizer in enhancing the mobility of cadmium in paddy soil.【Method】The experiment were conducted in pots grown with brown rice, and the potassium was applied in KCl and K_2SO_4, respectively, at rate of 0.10 g/kg soil(L), 0.20 g/kg soil(M) and 0.40 g/kg soil(H), measured in unit of K2 O. The soil was amended with sepiolite(S) at ratio of 10 g/(kg of soil). No K application was the control(CK).【Result】Immobilization of cadmium by sepiolite boost the biomass of the rice, and application of KCl reduced the biomass of the rice by 4.66%～11.47%, compared to CK. Treatment L insignificantly increased the rice yield by 2.69%, while M and H treatment reduced the yield by 1.10% and 14.97% respectively, compared to the CK. Addition of KCl to the amended soil enhanced the bioavailability of Cd by 41.67%～58.33%. Similarly,adding K_2SO_4 also increased the bioavailable Cd by 16.67%～33.33%. Compared with CK, the L, M and H treatment with KCL increased Cd content in brown rice by 53.38%, 46.15% and 200%, respectively, and the associated increase with K_2SO_4 was 7.69%, 38.46% and 23.08%, respectively.【Conclusion】In Cd-contaminated paddy soil amended by sepiolite, applying potassium in KCL and K_2SO_4 can both significantly improve Cd mobility and uptake by brown rice, particularly KCl at high application rate.