不同土壤质地稻田施用石灰的调酸降镉效果

Effect of Lime Applied to Rice Field with Different Soil Texture on Soil Acid Conditioning and Cadmium Passivation

【目的】探明不同质地稻田土壤上施用石灰的调酸降镉效果。【方法】选择湖南省长株潭地区的砂土、壤土、黏土稻田开展石灰的调酸降镉效果试验,分析3种土壤质地下施用石灰对土壤pH增量、土壤有效态镉含量降幅、稻米降镉效果的影响。【结果】施用石灰1500 kg/hm 2可显著提升土壤pH,降低土壤有效态镉含量,进而显著降低稻米对镉的吸收积累,调酸降镉效果表现为砂土>壤土>黏土、早稻季>晚稻季。早稻季施用石灰1500 kg/hm 2的土壤pH增加0.29~0.63个单位,土壤有效态镉含量降低13.91%~22.74%,稻米镉含量降低26.48%~56.21%;晚稻季增施石灰1500 kg/hm 2的土壤pH增加0.51~1.34个单位,土壤有效态镉含量降低18.20%~28.66%,稻米镉含量降低32.30%~50.52%;土壤pH每增加1个单位,砂土、壤土、黏土的早稻稻米镉含量降幅分别增加25.75%、44.93%和38.72%,晚稻则分别增加44.60%、80.24%和51.34%。【结论】不同土壤质地稻田施用石灰的调酸降镉效果不同,实际生产过程中应根据土壤污染特征、土壤pH以及土壤质地选择合理的石灰用量,尤其是黏土上应增加石灰用量以提升调酸降镉的效果。

【Objective】To investigate the effect of lime applied to paddy soil with different texture on regulating acid and reducing cadmium.【Method】The effects of lime on soil pH increase,available cadmium content decrease and cadmium reduction of rice were analyzed in sand,loam and clay paddy fields in Changzhutan area of Hunan Province.【Result】Lime application of 1500 kg/hm 2 can significantly increase soil pH,reduce soil available cadmium content,and then significantly reduce the absorption and accumulation of cadmium in rice.The effects of acid regulation and cadmium reduction were as follows:sandy soil>loam soil>clay,early rice season>late rice season.In the early rice season,the soil pH increased by 0.29~0.63 units of liming 1500 kg/hm 2 in the early rice season,the available cadmium content in soil decreased by 13.91%~22.74%,and the cadmium content in rice decreased by 26.48%~56.21%.In late rice season,soil pH increased by 0.51~1.34 units,the available cadmium content in soil decreased by 18.20%~28.66%,and the cadmium content in rice decreased by 32.30%~50.52%.The cadmium content of early rice in sandy soil,loam soil and clay increased by 25.75%,44.93%and 38.72%,and that of late rice increased by 44.60%,80.24%and 51.34%,respectively,with each increment of soil pH 1 unit.【Conclusion】The effects of lime applied to paddy fields with different soil textures are different.In the actual production process,a reasonable amount of lime should be selected according to soil pollution characteristics,soil pH and soil texture.In particular,the amount of lime applied to clay should be increased to improve the effect of acid regulating and cadmium reducing.