石灰降低稻米镉含量的效果及其影响因素

摘要

为探明施石灰降低镉污染酸性稻田米镉含量的效果及其影响因素,在湘潭市16个不同地点,开展石灰施用试验.以稻米镉含量的降幅为主要评价指标,分析了管理措施和土壤环境条件对施石灰降低稻米镉含量效果的影响.试验结果显示,施用生石灰750~1800 kg/hm2,土壤pH值平均提升0.16个单位,稻米镉平均含量由对照的0.29 mg/kg降至0.13 mg/kg.石灰施用量以1800 kg/hm2最佳,其稻米平均降幅可达58.3%.土壤本底pH值低于6.5时,随pH值的升高,施石灰降低稻米镉含量的效果增强.而随着土壤有机质含量和CEC的升高,施石灰降低稻米镉含量的效果呈明显的减弱趋势.%In order to find out the effect of lime on reducing cadmium content in rice field polluted by acid cadmium pollution and its influencing factors, the lime test was carried out at 16 different sites in Xiangtan. Taking the decline of cadmium content of rice as the main evaluation index, the effects of management measures and soil environment conditions on the effect of lime on reducing cadmium content in rice were analyzed.The results showed that applying the lime 750-1800 kg/hm2, the soil pH value increased by 0.16 units on average, and the average cadmium content of rice decreased from 0.29 mg/kg to 0.13 mg/kg. The optimum amount of lime was 1800 kg/hm2, and the average decrease of cadmium content in rice was 58.3%. When soil background pH value was lower than 6.5, with the increase of pH value, the effect of lime on lower the cadmium content in rice was enhanced.With the increase of soil organic matter content and CEC, the effect of lime on lower the cadmium content of rice decreased obviously.