棉秆炭对碱性水稻土壤-水稻中镉迁移转化的阻控作用

Control of Cadmium Migration and Transformation in Alkaline Paddy Soil-Rice Using Cotton Stalk Biochar

为研究棉花秸秆生物质炭添加对碱性水稻土壤-水稻体系中镉迁移转化的影响,通过室外盆栽试验,以水稻品种特丰优2号为试验材料,在添加外源镉含量为0、1、4和8 mg·kg^-1的碱性水稻土中分别施入炭土质量比分别为0%、1%、2.5%和5%的棉花秸秆生物质炭,待水稻收获后,分析不同含量镉胁迫处理下,施用不同量棉秆炭对碱性水稻土壤pH、养分和水稻体内镉富集、转移情况及镉在土壤中的赋存形态的影响.结果表明:①添加棉秆炭可以显著提高土壤养分(P<0.05),其中5%量的棉秆炭添加后,相比于对照组土壤有机质增加了25.74~47.53%,速效钾提高了3.16~4.25倍.②施用生物质炭可以显著降低土壤及水稻体内镉含量(P<0.05),尤其5%量的棉秆炭施用后,Cd4和Cd8含量下糙米镉含量分别由0.31 mg·kg^-1和0.43 mg·kg^-1降低到0.15 mg·kg^-1和0.10 mg·kg^-1,达到国家标准范围.生物质炭可以显著降低镉在土壤-水稻体系的富集、转移系数,并使残渣态镉含量增多,弱酸提取态、可还原态、可氧化态镉含量显著降低(P<0.05).③土壤pH、电导率和养分各指标与水稻体内镉含量和土壤中弱酸提取态、可还原态和可氧化态镉含量有极显著负相关关系,与残渣态镉含量呈正相关关系(P<0.05).上述研究结果说明,棉秆炭的施用可增加土壤养分,对碱性水稻土和水稻体内镉的富集、转化有显著的阻控作用.

We investigated the effects of cotton stalk biochar addition on the soil nutrient characteristics of alkaline paddy soil and the migration and transformation of cadmium in a soil-rice system.An outdoor pot experiment was conducted with Tefengyou 2 rice as the testing material.We added cotton stalk biochar(0%,1%,2.5%,and 5%)in the alkaline paddy soil with cadmium content of 0,1,4,and 8 mg·kg^-1.After rice harvesting,the effects of different concentrations of cotton stalk biochar on alkaline soil physical and chemical properties,cadmium enrichment and transfer in rice,and the occurrence of cadmium in soil were analyzed under different concentrations of cadmium stress.The results showed that①adding cotton stalk biochar can effectively increase soil nutrient(P<0.05).After the addition of cotton stalk biochar,the organic matter increased by 25.74%-47.53%,and the available potassium content increased by 3.16-4.25 times.②Cotton stalk carbon can reduce the cadmium content in soil and rice,especially after the application of 5%cotton stalk carbon,The cadmium content of brown rice at Cd4 and Cd8 concentrations decreased from 0.31 mg·kg^-1 and 0.43 mg·kg^-1 to 0.15 mg·kg^-1 and 0.10 mg·kg^-1,respectively,reaching the national standard.Cotton stalk biochar can significantly reduce the enrichment and transfer coefficient of cadmium in soil-rice systems and can increase the cadmium content in the residual cadmium but decrease the acid extractable cadmium,reducible cadmium,and oxidizable cadmium content(P<0.05).③Soil pH,conductivity,and nutrient indicators were significantly negatively correlated with cadmium content in rice and acid extractable cadmium,reducible cadmium,and oxidizable cadmium content in soil and were positively correlated with cadmium content in residual cadmium.The above results indicate that the application of cotton stalk biochar can significantly improve the soil nutrient of alkaline cadmium-contaminated paddy soil,and the application of cotton stalk biochar has a significant control effect on the migration and transformation of cadmium in alkaline soil and rice.