| In order to investigate the effect of in-situ passivation on the cadmium-lightly polluted wheat field,under the field test conditions,lime,biochar with lime,bio-organic fertilizer with lime and porous ceramic nano-material with lime were studied. Effects of combined chemical agents on soil nitrogen,phosphorus and potassium contents,soil pH,soil available Cd content,soil Cd chemical form,wheat grain Cd content and wheat yield in cadmium-contaminated farmland were investigated. The results showed that in the mild Cd contaminated farmland with soil Cd background value of 0.337 mg·kg-1,the passivation treatments could increase soil nutrient content and pH value to different extent,and reduce the Cd content of wheat grain and soil. The Cd content promotes the Cd morphology in the soil from the acid-soluble,and reducible states that are easily absorbed by the crop,compared to the oxidizable and residual states that are not easily absorbed. Among them,the maximum reduction of Cd content in wheat grains was 40.0%,and the maximum reduction rate of soil DTPA-Cd was 43.7%,and the pH value of soil was increased by 0.35. The correlation analysis of each index showed that the soil DTPA-Cd content was positively correlated with soil acid-soluble Cd and wheat grain Cd content,and was negitively correlated with soil oxidizable Cd,and was significantly positively correlated with the reducible state Cd content. There was a significant positive correlation between Cd in reducible state and acid-soluble Cd content and wheat grain Cd content. |
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