The Preparation And Assessing Sewage Sludge-Cornstalk-Based Biochar As A Soil Conditioner

With the unreasonable human activities,soil degradation has become an important factor which restrict the development of agriculture.Soil degradation has seriously affected human survival by reducing land productivity,causing crop failure,increasing greenhouse effect and polluting environment directly.The results have been confirmed that biochar can effectively improve the soil physical and chemical properties and soil microbial activity,increase soil organic carbon and soil nutrient content,reduce the leaching of soil organic carbon and soil nutrien and promote plant growth.In addition,the reasonable disposal of sewage sludge is also a worldwide problem.In this study,Sewage Sludge–Cornstalk–based Biochar(SCBC)was prepared from mixture of sewage sludge and cornstalk by using KOH as activator.Its soil improvement potential were investigated by ryegrass pot assays(120d).The following is studied:(1)The differents performances of different SCBC with different mixing ratio of straw and sludge in specific surface area,pore number and heavy metal content.(2)The effect of SCBC on plant growth was analyzed by measuring 7-days germination rate,biomass and chlorophyll content of ryegrass.(3)The effect SCBC to soil physical and chemical properties,available nutrients content,various soil organic carbon content and soil enzyme activity.Moreover,the effect of SCBC to leaching characteristics were also been studied,such as nitrogen and phosphorus,organic carbon and heavy metal.The paper mainly obtains the following conclusions through above reesarch:(1)SCBC has large specific surface area and micropore number.SCBC30 has the best adsorption potential.There was no significant difference between the pH and methylene blue adsorption value between different SCBC.The heavy metal content was consistent with the agricultural standard.(2)SCBC could obviously promote the growth of plants.The 7-day germination rate,biomass and chlorophyll content of ryegrass increased significantly.The 7-day germination rate reached 93.3%,which increased by 23.53% with the applicition of SCBC30 of 4%.The biomass of root and green part was increased significantly,and the proportion of root biomass increased.(3)SCBC significantly improved the soil properties.Among them,soil cation exchange capacity,total nitrogen,total phosphorus,total organic carbon,readily oxidizable organic carbon and water soluble organic carbon increased significantly with the SCBC.However,the proportion of available nitrogen and phosphorus,soil enzyme activity and microbial biomass carbon reached maximum at 3% or 4%.(4)In the leaching experiment,SCBC effectively reduced the volume of solution and the loss of soil water.The content of nitrogen and phosphorus,organic carbon and heavy metal content in leaching solution decreased,which showed SCBC could reduce the loss of organic carbon and nutrients,and passivate heavy metals in soils.This study showed that the SCBC prepared from the mixture of straw and sludge has significant improvement on soils properties,which could promote the growth of plants.The inprovement was most signifiant when the application of SCBC30 was 3%.