Effects of Rural Organic Waste Composts on Soil-red Skin Radish System and Ecological Risk Assessment
The soil-red skin radish system was taken as the research subject.A pot experiment was conducted to study the effects of different proportions(0,5％,10％,15％,20％)of rural organic waste compost on soil physicochemical properties,heavy metal content of soil and plant,plant biomass,and to evaluate the ecological security of soil.The results showed that the application of rural organic waste composts significantly increased the soil available nitrogen,available phosphorus content,organic matter content and red radish biomass(P＜0.05),and increased the pH of soil.When the application ratio was 5％and 10％,the pH of soil increased significantly(P＜0.05).After applying rural organic waste composts,except for no significant changes of Cu(P＜0.05),the total amount of Cd,Pb,Zn,and Cr in soil all increased,and the potential ecological risk of the soil increased.Among them,the total amount of soil Pb increased significantly(P＜0.05)by 20.49％-92.04％compared to the control.When the fertilization ratio were 15％and 20％,the total amount of Cd and Zn in soil increased significantly(P＜0.05)by 19.72％-34.75％and 8.55％-21.79％,respectively.When the fertilization ratio was higher than 5％,the total amount of Cr increased significantly(P＜0.05)by 19.51％-63.04％compared to the control.After the application of rural organic waste composts,the Cd content in various parts and Pb content in the root of red radish were reduced to a certain extent.While the Zn,Cr,and Cu content in the root were all increased,all of which met the GB 2762-2017 National Food Safety Standard for Contaminants Limits in Food.In general,among the five heavy metals,Cd was the most important element affected the soil ecological risk,and its contribution rate was as high as 76％.Redundancy analysis revealed that pH was the main factor that influenced the content of heavy metals in the soil,and the content of Cd and Pb were found to be significantly affected by soil physical and chemical indexes(P＜0.05).
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