Effect Of Biochar-amended Soil Conditioner On Improving Degraded Soil

This study is under the background that the arable land of soil in China is decreasing year by year,degraded soil is reused and strict requirements on soil environmental quality are met.Pot experiments were used to analyze wheat biomass,soil physical and chemical properties,soil respiration and soil enzyme activity of three kinds of degraded soils:22 years of vineyard soil,11 years of greenhouse soil and soil from mine reclamation areas after biochar-amended soil conditioner was added,and the effect and mechanism of carbon-based soil conditioner on improving degraded soil were clarified.The method of artificial simulation of heavy metal Cd and Pb contaminated soil was adopted.Cd contaminated soil was set with three gradients of 0,2.5 mg?kg-1and 10 mg?kg-1respectively,and Pb contaminated soil was set with three gradients of 0,500 mg?kg-1and 800 mg?kg-1respectively.Soil conditioner was added to cinnamon soil,brown soil and black soil,and the biomass of rape,Cd and Pb content in rape and bioavailability were measured after biochar-amended soil conditioner was applied.The effect and mechanism of biochar-amended soil conditioner on remediation of heavy metal Cd and Pb were clarified by tessier classification method.The results are as follows:Biochar-amended soil conditioner can improve soil p H value,soil nutrients and electrical conductivity(EC);Adding conditioner can improve the respiration of soil and make the respiration of degraded soil close to that of farmland soil.Conditioner can improve related enzyme activity,increase urease,neutral phosphatase,catalase and cellulase activity,and reduce polyphenol oxidase activity,which indicates that soil microbial activity improves soil enzyme activity,facilitates humus formation,facilitates decomposition of simple organic substances(litter and harmful substances)returned by plants to soil,promotes release of nutrients such as nitrogen and phosphorus,and improves soil resistance.The increase of heavy metals(Cd and Pb)in soil will inhibit the growth of small rape and reduce its biomass.After applying conditioner,the biomass of small rape will increase,and it will increase with the increase of conditioner dosage.The application of conditioner can effectively reduce the absorption of heavy metals(Cd,Pb)by canola,reduce the bioavailability of heavy metals,and further reduce the harm of heavy metals to plants,and its inhibitory effect of Cd on heavy metals is better than that of Pb.Through tessier continuous extraction method,it is known that adding conditioning agent can passivate Cd and Pb in soil to some extent,change the forms of heavy metals Cd and Pb in soil,and make them transform from active exchange state and carbonate adsorption state to stable organic binding state and residue state,and its passivation efficiency of heavy metals Cd is better than Pb.In summary,the experiment of improving degraded soil with biochar-amended soil conditioner showed that biochar-amended soil conditioner had certain improvement effect on vineyard continuous cropping soil,greenhouse continuous cropping soil,reclaimed raw soil and heavy metal contaminated soil(Cd,Pb).The application of conditioner can increase soil permeability,improve soil respiration and enzyme activity,promote soil nutrient circulation and reduce continuous cropping obstacles.At the same time,the conditioner can also passivate heavy metals(Cd,Pb)in soil,change the morphological distribution of heavy metals in soil,and reduce the toxic effects of heavy metals on plants.