Effects Of Combined Amendments On Migration Of Cadmium And Arsenic In Soil-rice System

Heavy metal pollution of farmland soil in China is a serious situation,which has posed a threat to food security and become a major strategic demand that needs to be solved urgently at present.In this paper,field experiments were conducted to study the effects and mechanism of two groups of amendments combined with application on the absorption and accumulation of Cd and As in rice,and to screen the safe,efficient,stable,cheap and easily popularized soil amendments,so as to provide technical support for the safe utilization of cultivated land and the prevention and control of heavy metal pollution in rice.The main results are as follows:(1)The application of six amendments can reduce the content of Cd in all parts of rice,increase the content of Fe in root surface iron film,and prevent the migration of Cd to the aboveground part of rice,but it has no significant effect on the content of As.The addition of lime had a significant effect on soil p H value and soil bioavailable Cd content(P<0.05).Through the range analysis,the optimal combination and application scheme for reducing Cd content in rice were as follows: lime(120 kg/ mu),magnesium fertilizer(12 kg/ mu),silicon fertilizer(30 kg/ mu),iron fertilizer(24 kg/mu),manganese fertilizer(1.8 kg/ mu)and phosphate fertilizer(24 kg/ mu).The optimal combination and application scheme for reducing inorganic As content in rice were As follows: lime(90 kg/ mu),magnesium fertilizer(36 kg/ mu),silicon fertilizer(50 kg/ mu),iron fertilizer(48 kg/ mu),manganese fertilizer(1.2 kg/ mu)and phosphate fertilizer(36 kg/ mu).(2)The content of Cd in all parts of rice and inorganic As in rice could be reduced by the combination of three amendments.However,there was no significant change in Fe content in root surface iron film.The addition amount of red mud had a significant influence on the p H value,bioavailable Cd and As content of soil(P<0.05).Through range analysis,the better combination of red mud(120 kg/ mu),silicon fertilizer(30 kg/ mu)and phosphorus fertilizer(36 kg/ mu)can reduce the content of Cd and inorganic As in rice.(3)The results of field pilot showed that the p H value of the soil was significantly increased(P<0.05).Reduce the content of bioavailable Cd and As in soil;Reduce the content of Cd and As in rice,and the content of Cd and As in rice is lower than the limit of < 0.2mg/ kg i n the food pollutant limit standard(GB2762-2017).(4)The results of economic benefit analysis showed that the combined amendments in this study had low application amount per mu,low cost,and promoted the growth of rice,increased the yield of rice,and had a higher application prospect.