Effect Of Municipal Organic Wastes Biochar On Soil Environment And Greenhouse Gas

Biochar technology can realize the municipal organic waste recycle,reuse andreduction.It can increase carbon sequestration, serve as soil active conditioners andimprove soil fertility when stored in soil, it has significant effect to improve crop yieldsand mitigate global warming. Thus, researchers recently focused on biochar technologymore than before. However, the raw material in previous studies was limited, such asbiomass of straw, vegetation, sludge, bamboo. Few studies has beencarried out withmunicipal organic waste pyrolysis as the raw material. Meanwhile, the mechanism ofcarbon sequestration and soil performance improvement has been rarely studied.. In thispresent study, biochar produced from municipal organic wastes was added to soil withdifferent temperature and dosage in a lab-scale and the effects on physical and chemicalcharacteristics of soil were extensively studied. Pyrolysis temperatures of municipalorganic wastes biochar were600℃,700℃and800℃, respectivelyAnd proportion of0.5%,1%and2%of biochar was dosed to the soil. The purpose is not only to provide anew way to process municipal organic waste, resource utilization and energyconservation and emissions reduction, but also to provide theoretical basis foragricultural application of biochar technology. Conclusions were drawn as follows:①Results showed that the addition of biochar can improve soil pH value, cationexchange capacity and organic matter content. The increase rate of soil pH value, cationexchange capacity and soil organic matter was correlated well with the final temperatureincreasing of the biochar production when biochar addition was the same.When adding800℃biochar,soil pH value,cation exchange capacity and organic matter contentincreased0.55~0.81,3.76cmol/kg~4.41cmol/kg and4.09g/kg~6.59g/kg,respectively.Inthe case of using the same biological carbon, the increase rate of soil pH value, cationexchange capacity and soil organic matter was the same with the increasing amount ofbiological carbon.When adding2%biochar,soil pH value,cation exchange capacity andorganic matter content increased0.30~0.81,2.27cmol/kg~4.41cmol/kg and4.15g/kg~6.59g/kg, respectively.②Soil CO2and N2O emissions were well inhibited with biochar addition. After36weeks tests,the control group of soil CO2emission flux is44.702mg·m-2·h-1;the rangeof experimental group was20.219mg·m-2·h-1~38.635mg·m-2·h-1. The control group ofsoil N2O emission flux is98.400μg·m-2·h-1.The range of experimental group was 22.186μg·m-2·h-1~80.159μg·m-2·h-1.The soil CO2and N2O emissions reduced moreobviously as the final pyrolysis temperature increased gradually with the same amountbiochar addition. And better inhibition effect of CO2and N2O emissions from soil wasobserved as the amount of biological carbon increased wtih the same final temperaturebiochar to soil.Therefore, the effect was the best when adding2%of the800℃biochar.③The effect of biochar on improving soil physical and chemical properties andinhibition greenhouse gas emissions flux were affected by the structure and property ofthe biochar. High final temperature (800℃) biochar, with large BET specific surfacearea and high porosity and high pH value, showed a stronger and more stable effect.④Significant correlation between room temperature, soil pH, organic mattercontent of the cation exchange capacity, N2O emission flux and on CO2emissions fluxwas obeserved. Temperature effect on the emission rate of CO2is the largest and thesecond is the soil pH value and soil organic matter content following with soil cationexchange capacity; Temperature effect on N2O emission rate is the largest and thesecond is the soil pH value, following with soil cation exchange capacity and soilorganic matter.