Control Of Rice Cadmium Contamination Through Heavy Metal Passivants And Foliar Fertilizers

Rice,the world’s second largest major food crop,plays an important role in agricultural production.The country by heavy metal pollution of up to 20 million hectares of cultivated land.Soil environmental quality issues are directly related to the safety of agricultural products.Due to the large area of soil pollution,China’s annual production of heavy metal pollution of food up to 12 million tons.Therefore,it is of great practical significance to reduce the cadmium content of heavy metals in rice,to protect the health and safety of rice,to maintain people’s health and to improve the competitiveness of rice products.In this study,several soil passivators and leaf barrier agents were screened out.Three experiments were conducted:soil passivation test,leaf barrier inhibitor test,soil passivator combined with leaf barrier inhibitor test,Study on the Control Effect of Cadmium Accumulation and Yield of Rice in Cadmium and Paddy Field.The main results are as follows:(1)Soil passivator test showed that:in the mild soil pollution conditions,respectively,add150kg/mu of JDF,MF,iron-based bio-carbon,iron-based humic acid four soil passivation treatment of cadmium contaminated rice Soil,rice yield has a certain degree of increase,of which,MF the best,significantly increased the yield of rice.The contents of cadmium in rice treated with four kinds of passivating agents decreased by 57%~68%,30%~47%,25%~40%and 41%~45% respectively,which reached the national food hygiene and safety standard,The effect of different passivating agent on controlling cadmium content in rice was as follows:JDF> MF> iron-based humic acid potassium> iron-based biochar.(2)The four passivating agents used in this study are to reduce the soil cadmium content by reducing the bioavailability of heavy metals in the soil.The mechanism is to convert the soil cadmium from exchangeable state to residue.Easy to absorb the effective state of hard to absorb the invalid transformation.The contents of cadmium in the soil treated with four passivants were significantly lower than those in the blank control group.The effects of different passivants on soil cadmium content were as follows:iron-based bio-carbon>iron-based humic acid>MF>JDF.(3)Foliar barrier test showed that:1L/mu of 1#silicone,2#silicone+Se and 3#inorganic silicon leaf barrier,and treated rice were sprayed before heading stage after jointing stage Cadmium content decreased by 28%~40%,28~33%,2%~26%,respectively,to the national food safety standards,different leaf barrier to control the cadmium content of rice from good to poor are:1#Silicone>2#Silicone+Se>3#Silicone.The mechanism of foliar barrier to control cadmium content in rice is to block cadmium in stems and leaves and rice husk,and to inhibit rice transport to achieve the reduction of cadmium content in rice.Three kinds of silicon-containing leaf barrier agents were used to increase the yield of rice.Compared with early rice,the effect of leaf barrier on the yield of late rice was better.(4)In this study,two kinds of soil passivation combined with leaf barrier technology,the treated cadmium content of rice were reduced to 0.2mg below,reached the national foodhygiene and safety standards,by 1#silicone+iron-based humic acid Potassium(1#Si+Fe-K)treatment is better.The content of cadmium in paddy soil treated with combination technology was reduced to 0.3mg,which reached the national food hygiene and safety standard.Among them,the treatment effect of 1#silicon+iron-based bio-carbon(1#Si+Fe-C)was better.The effect of two kinds of combined techniques on cadmium-contaminated rice field is better than that of single application,which can not only reduce the cadmium content in soil,but also inhibit the absorption of cadmium in rice,and has no obvious effect on rice yield,which is superior to single application.