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JournalofResourcesandEcologyVol.1,No.2ReportReceived:2010-05-10Accepted:2010-05-31Foundation:theNaturalScienceFoundationofChina(40871146,40571157),MinistryofAgricultureOfChina(200803033-B0204),MinistryofScienceandTechnologyofChina(2008BAD95B05),ChineseAcademyofSciences(KZCX2-YW-Q1-07)andtheInternationalS&TCooperationProgramofChina(GrantNo.2009DFA31110).*Correspondingauthor:XIEZubin.Email:zbxie@issas.ac.cn.1IntroductionGlobalwarminginducedbygreenhousegases(GHGs)emissionshasbeenareality,andcuttingGHGsisbecom-ingmoreurgentthaneverbeforetocombatglobalwarm-ing.Asamethodtohandleagriculturalwastes,compostusecanbetracedto475B.C.inChina,andhasbeencon-sideredtobeoneofsustainableproductivepractices,asthecompostformationprocessfromthewastescande-stroypathogens,killweedseeds,convertnitrogenfromunstableammoniatostableorganicforms,andreducethevolumeofwastes(Imbeah1998).However,compostingwasrecognizedasoneofimportantanthropogenicsourc-esforgreenhousegases,anditwasfarfromattention.Composts,inparticularintensivecomposting,wouldpro-duceconsiderableamountofCO2,CH4andcertainN2O.Livestockmanurecontributessignificantlytoatmosphericmethane(CH4)andnitrousoxide(N2O),whichgloballyaccountsfor5%–6%oftotalemissionofCH4(Hoganetal.1991;Rotmansetal.1992)and7%oftotalN2Oemis-AHolisticEvaluationofCO2EquivalentGreenhouseGasEmissionsfromCompostReactorswithAerationandCalciumSuperphosphateAdditionLIUJinshan1,2,XIEZubin1*,LIUGang1,ZHANGJiabao1,BEIQicheng1,2,HUANGPing1,2,SUNHuifeng1,2,XUYanping1,2,ZHUJianguo1andTANGHaoyan11StateKeyLaboratoryofSoilandSustainableAgriculture,InstituteofSoilScience,CAS,Nanjing210008,China;2GraduateUniversityofChineseAcademyofSciences,Beijing100049,ChinaAbstract:Compostprovidesbenefitssuchaspathogeninactivation,weedsuppression,slowreleaseofnutrients,soilimprovement,waterconservation,andisanadvantageoustoolinmovingtowardsmoresustainableagriculturalsystems.Lotsofgreenhousegases(GHGs)especiallyCH4areemittedfromtheheapduringcompostingprocess,whichplayanimportantroleinglobalwarming.ThepurposesofthisstudyweretoquantifyandcharacterizetheGHGsemissions,soastocompareandoptimizetheoperationconditions,thentominimizeGHGsemissions.WeexaminedGHGsemissionsfromcompostinginforcedaerationsystemsandturningsystemswithorwithouttheadditionofcalciumsuperphosphate(CS),usingthestaticchambermethod.Thecompostdegraded51%-55%ofinitialtotalcarbon(TC)inturningpiles,whileabout44%inforcedaerationpilesafter76dayscomposting.CH4emissionsfromturningpileswithandwithoutCSwererespectively15.35and15.27gMg-1drymaterial(DM),higherthanforcedaerationpiles(7.76gMg-1DM,withCS,and3.22gMg-1DM,withoutCS).N2Oemissionswerelessthan0.1%ofinitialtotalnitrogen(TN)intheforcedaerationpiles,and-0.1%ofinitialTNintheturningpiles.Energyconsumptionusedfortreatingmanureequaledto3.27,3.4,12.29and11.89kgCO2-CequivalentMg-1DM,forturningwithCS,turningwithoutCS,forcedaerationwithCS,forcedaerationwithoutCS,respectively.TheadditionofCShadlittleeffectonGHGsemissions,duetohighporosityandadequateaerationcausedbylargedoseofstrawasbulkingagent.Althoughforcedaerationcompostingisanintensivetechnologywidelyusedinlarge-scaleprocessingofmanurewastesforlandsavingandeasyoperation,turningaerationmaybemoreappropriateinruralareasofChina,consideringthelessconstructioncostandgreenhousegasemissions,anditshighefficiencyindegradingorganiccarbon.Keywords:composting;methane;turning;phosphorussion(Khaliletal.1992).Haoetal.(2004)reportedthatGHGsemission(CO2-Cequivalent)wasgreaterthantheinitialTCduringcompostingofstraw-beddedmanure.Staticpassiveaerationsystemrevealedhigh(9.9%TN)N2OemissionandhighCH4emissionof12.6%volatilesolids(VS),whileCH4emissionaccountedforonly0.4%ofVSforturningsystem(Szantoetal.2007).CH4andN2Oproductionduringcompostingisami-crobeinvolvedprocess,whichismainlyimpactedbysub-strateavailability,oxidationpotentialandelectronaccep-tors.Theforcedaerationsystemcanincreaseoxidationpotentialofcompostingpiles,itcanreduceCH4emission.However,duetothelackofinformationonwhetherthelesscompostingGHGsemissionscanoffsetthemoreen-ergyconsumption,theeffectofforcedaerationonGHGsemissionsisunknownyet,ascomparedwiththeturningtreatment.TheabilityofanH2-scavengingreactiontocompetefortransferredelectronsdependsonredoxpotentialoftheter-minalelectronacceptorswithSO42–CO2/CH4(Cord-Ru-wischetal.1998).ThisSO42–dependentinterspeciesH2transferresultsinamorecompleteoxidationoforganiccarbonsubstratesyieldingmoreCO2andlessCH4thanmethanogenscouldproducealone(Achtnichetal.1995).ThepresenceofSO42–wouldinhibitCH4emission,andhasbeensupportedbythefindingofHaoetal.(2005)thattheadditionofphosphogypsumreducedCH4emis-sion,possiblythroughinhibitionorcompetitioneffectsofSonCH4production.Therewassimilarprocessinpaddysoil(Fumotoetal.2008)andpeatland(Diseetal.2001),thatelectronacceptorssuchasSO42–canreduceCH4emis-sion,asSO42–reducerscancompetewithmethanogensfororganicsubstratesandH2(Lovleyetal.1983).AlthoughtherearesomereportsonGHGsemissionsduringcomposting(Haoetal.2005;Szantoetal.2007),obviouslyitisnotyetwellunderstoodofhowtoreduceGHGsemissions