| The current form of heavy metal pollution in farmland soil is severe,and soil heavy metals are a serious threat to the quality and safety of agricultural products.Soil conditioners are widely used in the practice of heavy metal cadmium pollution remediation.There are various types of soil conditioners,and their effects vary greatly.In this study,different types of soil conditioners(composite materials,siliconcalcium substances,clay,etc.)were first screened through literature search.Minerals,organic materials,phosphorus-containing substances,microbial inoculants,biochar,new materials and industrial byproducts)on the soil cadmium pollution remediation effect of experimental research results,using the integrated analysis method to quantitatively and systematically explore the effects of soil conditioners on soil physicochemical properties,the effect of soil Cd available content and rice Cd content,clarify the source of heterogeneity and the main influencing factors,and focus on analyzing the differences in the application effects of different types of soil conditioners.At the same time,taking silicon-calcium conditioners as examples,the research on the safe utilization and restoration technology of soil Cdcontaminated farmland was carried out in Xinyu City,Jiangxi Province and Chuxiong Prefecture,Yunnan Province,and the restoration effect of applying silicon-calcium conditioners was discussed.Evaluate the repairing effect of the tested conditioners.The main findings are as follows:(1)Meta-analysis of the effects of soil conditioners on soil physicochemical properties.The results showed that the application of soil conditioners could significantly increase soil p H,organic matter and soil CEC content(P<0.05),and the average effect value increased by 8.65 %,5.77 % and 6.28 %,respectively.The effects of conditioners on soil physicochemical properties and conditioning It is related to factors such as the type of agent,the level of application rate,soil p H and soil texture.In terms of the types of conditioners,the application of clay minerals has the largest increase in soil p H value,the application of organic materials has the largest increase in soil organic matter content,and the application of silicon and calcium substances has the largest increase in soil CEC content;The soil texture is loamy,acidic(p H<6.5)soil environment,the application of conditioner has the greatest increase in p H value,and the increase of the organic matter content and CEC content of the application of conditioner in different soil textures is in order: loam > clay > sandy soil.(2)Meta-analysis of the effects of soil conditioners on soil available Cd content and rice Cd content.The results showed that the application of different types of conditioners significantly reduced the available Cd content in soil and rice Cd content(P<0.05).The type of conditioner and soil p H are the key factors affecting the effective content of soil Cd.After the application of the conditioner,the effective content of soil Cd decreased by 26.93 %,and the Cd content of rice decreased by 41.17 %,the clay mineral conditioner had the largest reduction of effective Cd content,which was 41.07 %,and the siliconcalcium conditioner had the best effect of reducing the Cd content of rice,with a reduction of 44.77 %.In addition,compared with neutral(6.5-7.5)and alkaline(p H>7.5)soil environment,the effect of applying conditioner in reducing rice Cd content was most prominent in acidic(p H<6.5)soil environment.(3)Based on the Meta-analysis method,the effects of soil conditioners on soil physicochemical properties,soil Cd available content and rice Cd content were studied,and correlation analysis was carried out on the main response indicators.The results showed that soil Cd available content and p H value were significantly correlated Negative correlation(P<0.05),positive correlation with organic matter content but not significant(P>0.05),negative correlation with CEC content and also not significant(P>0.05);There was a significant positive correlation between soil Cd available content and rice Cd content after microbial inoculants and new material conditioners(P<0.05).(4)Field experiments were carried out in Xinyu City,Jiangxi Province and Lufeng Prefecture,Yunnan Province to study the remediation effect of silicon-calcium conditioners on soil Cd pollution.The application of TX,NL,ZB and YTK conditioners can significantly increase the p H value(P<0.05),by0.83,0.47,0.73,and 0.77 units,respectively.Under the experimental conditions of Chuxiong Prefecture,the soil Cd available content of the conditioners was significantly decreased(P<0.05),with a decreasing range of 48.17 %-72.56 %;and available potassium)were more complex,and only some of the conditioning agents had significant effects;the five tested conditioning agents could reduce the Cd content of rice,and the decrease of Cd content in rice under the experimental conditions in Xinyu City,Jiangxi Province reached significant(P<0.05).),with a decrease of 42.70 %-73.28 %;under the experimental conditions in Xinyu City,Jiangxi Province,the five tested conditioners all had the effect of increasing rice yield,but it was not obvious(P>0.05),and only two conditioners,NL and ZB,were applied in the Chuxiong Prefecture experiment in Yunnan.The effect of the agent on increasing production.(5)Field experiments were carried out in Xinyu City,Jiangxi Province and Lufeng Prefecture,Yunnan Province with silicon-calcium conditioners to study the remediation effect of silicon-calcium conditioners on soil Cd pollution.Under the experimental conditions in Xinyu City,Jiangxi,the Cd content of rice was significantly negatively correlated with soil p H and CEC content(P<0.05),and positively correlated with soil Cd available content,but not significantly.Potassium content was significantly positively correlated(P<0.05),and under experimental conditions in Chuxiong Prefecture,Yunnan,rice Cd content was significantly negatively correlated with alkaline hydrolyzable nitrogen content(P<0.05).Based on soil p H,rice Cd content,rice yield,The five indicators of soil Cd available content and conditioner cost were used to establish a gray correlation model of the restoration effect of the five tested conditioners.The results showed that the restoration effect of TX conditioner was the most prominent in the two test sites.In the future soil Cd pollution It can be prioritized as a product for promotion and application in the practice of remediation and governance. |
PDF Full Text Request