Immobilization Of Cadmium Contaminated Soil By Chelated Iron Amendment And Improving Cadmium Concentration In Maize

With the development of industrial and agricultural production,the increasingly serious pollution of heavy metal cadmium?Cd?in farmland soil is threatening the quality and safety of agricultural products in China.The research and development of the technology to reduce the bioavailability of heavy metal Cd in soil under regional conditions is of great significance for ensuring the safe production of food in China.In this paper,the brown soil contaminated with Cd?10 mg/kg?was used as the test soil,and corn was used as the research object.The pot experiment method was used to study two different forms of chelated iron amendments EDTANa₂Fe and EDDHAFe?the application amounts were 30,60,120 and 180kg/ha?affects soil Cd transformation,maize growth and development and Cd distribution of different organs?roots,stems,leaves,grains?,and through changes of some indexe such as soil pH,organic matter,cation exchange capacity?CEC?,available Cd and available iron to explore the mechanism of chelated iron inhibiting Cd activity in soil,and providing a theoretical basis for the safe production of Cd-contaminated farmland corn.The main conclusions are as follows:?1?Compared with no iron amendments,soil pH increased 0.17,0.15,0.28 units respectively under 120 kg/ha EDTANa₂Fe and 120,180kg/ha EDDHAFe treatments;and cation exchangeable content were increased by 10.71%,11.90%,14.29%and 11.31%respeactivly under 120 kg/ha EDTANa₂Fe and 60,120,180kg/ha EDDHAFe treatments;the application of chelated iron reduced the available cadmium in the soil by 9.60%to 28.64%;there was a significant negative correlation between soil pH and soil CEC and available cadmium content in the soil?P<0.05?.?2?Compared with no iron amendments,120 kg/ha EDTANa₂Fe and EDDHAFe treatments reduced the acid-soluble Cd content by 18.65%and 19.86%,respectively,and increased the residual Cd content by 89.12%and 96.01%.Among them,120 kg/ha EDDHAFe treatment exerted the most optimal performance?p<0.05?.?3?120 kg/ha EDTANa₂Fe and 60,120,180kg/ha EDDHAFe treatments significantly increased iron concentrations in the grains by 34.86%,36.88%,41.46%,and 44.05;120 kg/ha EDTANa₂Fe and 60,120 kg/ha EDDHAFe treatments significantly reduced the Cd content in the grains by 39.82%,42.67%,and 48.41%,respectively;There was significantly negative correlation between Fe and Cd concentration in grain?p<0.05?.?4?Compared with no iron amendments,120 kg/ha EDTANa₂Fe treatment had the largest increase in corn yield,at 30.45%;60 and 120 kg/ha EDDHAFe treatments increased the total corn root length by 39.72%and 48.68%,respectively,and the total root surface area increased by 19.95%And 22.98%.The result suggests that the application of 120 kg/ha EDDHAFe,given that less available Cd in soil,less Cd uptake and more iron contents by grain were performed best while high maize yields were maintained to some extent.