Effect Of Biochar On Rice Yield And Cadmium Content In Cadmium Contaminated Soil

In recent years,the area of cadmium-contaminated soil in my country’s farmland has increased,and there are widespread problems such as the abuse of chemical fertilizers.Therefore,we will study how to conduct safe rice production in soil contaminated by cadmium and reduce the accumulation of cadmium in rice as the research direction of agricultural safe production.Studies have shown that the soil amendment biochar has the ability to improve the soil environment and promote crop growth.However,there are few studies on the remediation effect of biochar combined with chemical fertilizers on heavy metal polluted rice fields.This study tried to find out the effects of biochar and combined chemical fertilizers on rice yield and grain cadmium content and its effect on cadmium pollution through field experiments.Repair effect,the research results show that:(1)Single application of biochar and combined application of biochar fertilizers significantly increased rice yield(p<0.05).After the single application of biochar,the rice yield increased with the increase of the amount of charcoal,and the highest increase was41.64%.The T2 J treatment with biochar combined with chemical fertilizers had the highest yield,which was 62.02% higher than the control.Both the single application of biochar and the combined application of biochar and chemical fertilizers significantly increased the effective panicle number and harvest index of rice(p<0.05).However,the combined application of biochar with chemical fertilizers significantly improved the total number of grains per panicle and the quality of 1,000 grains,and the rice seed setting rate only increased significantly when the single application of biochar was applied(p<0.05).(2)Both single application of biochar treatment and compound application of biochar fertilizer can significantly reduce the cadmium content of rice and soil.T2 J treatment has the most significant improvement effect on the cadmium content of rice grains,and the cadmium content is reduced by 43.33% compared with the blank control group.(p<0.05).Biochar and combined application of chemical fertilizers can significantly reduce the cadmium content in rice grains.(3)Effects of biochar on soil bacterial communities of different rice varieties the combination of biochar and chemical fertilizer significantly increased the soluble sugar content,proline content and Mg/K ratio of rice grains,while the soluble protein content and C/N ratio decreased with the increase of treatment level.Reach the lowest value during T2 J treatment.Both the single application of biochar treatment and the combined application of biochar fertilizer treatment significantly reduced the soil magnesium and potassium content,and they decreased with the increase of the amount of biochar.Single application of biochar can significantly increase the soil C/N ratio,and the soil C/N ratio is relatively stable.Compared with single application of biochar,combined application of biochar and chemical fertilizer can increase the content of soil magnesium,potassium,carbon and nitrogen,and improve the soil environment.(4)The yield,the ratio of magnesium to potassium,the ratio of carbon to nitrogen and the content of cadmium in rice grains of conventional rice varieties Zhongzao 39 and Xiangzaoxian 45 were higher than those of hybrid rice varieties Lingliangyou 211 and Lingliangyou 942.The growth status of conventional rice is better than that of hybrid rice in this experimental site.(5)Through the analysis of 16 S r RNA gene V3-V4 high-throughput sequencing technology,a total of 66 phyla,76 classes,135 orders,224 families,389 genera and 232 species of bacteria were obtained.The dominant bacterial groups in the soil are the same,mainly including Proteobacteria,Bacteroidetes,Nitrospirae and other major bacteria.Among them,Proteobacteria is the first dominant bacteria(average content of 40.6).%);Single application of biochar and combined application of biochar fertilizers changed the diversity of soil bacterial communities and the richness of bacterial communities.Different bacterial communities are affected by biochar inconsistently.When the amount of biochar applied is T2 treatment level,the soil bacterial community The structure and function have the biggest difference compared with the control.The different applied amount of biochar has an impact on the function of soil bacterial community.Biochar combined with chemical fertilizer treatment(T2J)can obtain the highest rice yield and the lowest cadmium content in rice grains on cadmium contaminated soil,improve rice quality,and increase the content of resistance indexes such as soluble sugar and proline in rice.Improve soil carbon to nitrogen ratio and physical and chemical properties,and change the structure and function of soil bacterial communities.So biochar combined with chemical fertilizer treatment(T2J)is a very good biochar combined treatment to reduce cadmium and increase production,which can improve the soil environment and provide a feasible technical guidance for the production of cadmium-polluted soil rice.