组配改良剂联合硅肥对Cd污染稻田的修复效果

Remediation effects of combined amendment and silicon fertilizer on Cd contaminated paddy soil.

选取湖南省浏阳市某Cd污染稻田进行田间试验,研究组配改良剂石灰石+海泡石(LS)、基施硅肥及叶面喷施硅肥对Cd污染稻田修复效果,结果表明:(1)基施硅肥90kg/hm^2和叶面喷施硅肥(0.2,0.4g/L)对土壤pH值无明显影响,添加LS(2250,4500kg/hm^2)的各处理均显著提高土壤pH值(P<0.05).(2)基施硅肥90kg/hm^2分别降低土壤交换态、毒性特征浸出(TCLP)提取态Cd含量20.0%和18.5%,叶面喷施硅肥对土壤Cd两种提取态含量无明显影响,添加LS的各处理(2250,4500kg/hm^2)分别使土壤交换态、TCLP提取态Cd含量降低25.8%~49.9%、26.4%~44.5%.(3)3种单一技术措施均能明显降低水稻各部位Cd含量,但降低糙米中Cd含量的效果低于3种技术措施的组合处理;“组配改良剂LS+基施硅肥+叶面喷施硅肥”各处理(JL1F1、JL1F2、JL2F1、JL2F2)使水稻糙米中Cd含量降低25.6%~70.5%.(4)“组配改良剂LS+基施硅肥+叶面喷施硅肥”的组合技术处理能显著降低土壤中Cd的有效性,显著降低水稻各部位中Cd含量,其中JL2F2处理效果最佳,能使对照糙米Cd含量从0.66mg/kg降低到0.19mg/kg,实现中重度Cd污染稻田的水稻安全生产.

A field experiment was conducted in a Cd-contaminated paddy field in Liuyang City,Hunan Province,and the remediation effects of combined amendment LS(limestone+sepiolite)and application of silicon fertilizer were studied.The results showed that:(1)Application of silicon fertilizer(90kg/hm^2)to the soil and treatments of spraying foliar silicon fertilizer(0.2,0.4g/L)showed no significant effects on soil pH values,while all treatments with LS application(2250,4500kg/hm^2)significantly increased soil pH(P<0.05).(2)Application of 90kg/hmof silicon fertilizer to soil significantly decreased exchangeable Cd concentration by 20.0%and TCLP(Toxicity Characteristic Leaching Procedure)extractable Cd concentration by 18.5%in soil.While spraying foliar silicon fertilizer had no significant effect on soil Cd availability.All treatments with LS application(2250,4500kg/hm^2)decreased exchangeable Cd concentrations by 25.8%~49.9%and TCLP extractable Cd concentrations by 26.4%~44.5%,respectively.(3)All three single technology treatments significantly decreased Cd concentrations in different rice tissues,but these Cd reductions in brown rice were lower than those combination treatments of the three technologies.The combination treatments(JL1F1,JL1F2,JL2F1,and JL2F2)decreased Cd concentrations in brown rice by 25.6%to 70.5%.(4)The combination technologies of“amendment LS+application of silicon fertilizer+spraying foliar silicon fertilizer”significantly decreased Cd availability in soil and Cd concentrations in all rice tissues.Among these combination technologies,JL2F2 showed the highest effect on reducing Cd concentrations in brown rice(from 0.66mg/kgto 0.19mg/kg),and realized the safe production of rice in this field with moderate to serious Cd pollution.