Effect Of Biochar Modified Sludge On Soil Improvement Of Rare Earth Mine

The soil in the mining wasteland is poor,whilethe sludge is rich in various nutrients and organic matter.Therefore,the application of sludge in mine soil remediation has broad prospects.Biochar has good porosity and large specific surface area,so it is feasible to use to inactivate heavy metals in sludge.In this study,the biochars of coconut shell as raw material.Pot experiment was conducted including four treatments,CK : soil,T1: soil + sludge,T2: soil + sludge + cane trash,T3: soil + sludge + cane tras h +3% biochar,each treatment were planted four species,including Acacia auriculaeformis,Eucalyptus urophylla,Canavalia gladiata and Jatropha carcas.Wedeterminedsoil and plant nutrients and heavy metal contentsindifferent treatments,to investigate the effects of sludgemodifiedby biocharon mining wasteland soil,plant growth,nutritional status and the absorption of heavy metals,at the same time,to explore the effects of different plant combined with biocharon the soil biological and physicochemical properties,different kind ofheavy metals in soil,which aim to provide feasible application directionfor the ecological restorationof rare earth mine and city sludge resource utilization.The main resultswere showedas follow:(1)The sludge applied improved the physical and chemical properties of rare earth mine soil,but decreased the content of total K in soil.The application of biochar significantly reduced the contents of total Nand total Pin sewage sludge mine soil.(2)The application of sludge and biochar had no significant effects on the height,ground diameter,total biomass of Acacia auriculaeformis.But for Eucalyptus urophylla,Jatropha curcas and Canavalia gladiata has played a significant role in promoting(except the ground diameter of Eucalyptus urophylla),and biochar treatment was significantly higher than other treatments.(3)The application of sludge can promote the absorption of N,P,K by four plants.Biochar applicationsignificantly increased the Ncontent of Acacia leaves,significantly reduced the absorption of root Pcontent of Jatropha curcas.The storage of N,Pand K in Canavalia gladiatawere the highestin biochartreatment.(4)The application of sludge increased the contents of C u,Zn,Cd and N i andreduced the content of Pbin four plants.Biochar significantly reduced stem Pb content of Acacia auriculaeformis,root Cd content of Eucalyptus Acacia,stem Zn,Cd,Ni of Canavalia gladiata,significantly increased the root C uabsorption of Canavalia gladiata.Under the same treatment,the absorption o f Pb,Cd and N i in four plants was less than that of Zn and Cu,and the absorption of Zn was the highest.The contents of heavy metals in roots of the four plants were higher,but in the stems and leaves were relatively lower.The cumulationof C u,Zn,Cd,N i in Canavalia gladiataweremaximum in biochar treatment.(5)Plant combined amendments on remediation of mine soil showed great differences.According to the comprehensive score of principal component,the results showed that:the scores of the plant combination modifier were higher than those of the plants in the mine soil,and the scores of the Canavalia gladiata combined biochar were the highest.