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SoilCarbonAccounting–theAustralianexample
JeffBaldock1andRachelBurgess2
1) CSIROAgricultureandFood,LockedBag2,GlenOsmond,SA5064,Australia
2) AustralianDepartmentoftheEnvironmentandEnergy,Canberra,ACT2601,
Australia([email protected])
TheAustraliangovernmenthasestablishedtheEmissionsReductionFund(ERF)toencourage
theadoptionofmanagementstrategiesthatresultineitherthereductionofgreenhousegas
emissionsorthesequestrationofatmosphericCO2-C.TheERFisenactedthroughtheCarbon
Credits(CarbonFarmingInitiative)Act2011(CFI).UndertheEmissionsReductionFund,
businesses,farmersandcommunitygroupscanearncarboncreditsbyundertakingprojectsto
reduceemissionsorsequestercarbon.Theseprojectsmustbeinaccordancewithapproved
methods.MethodssetouttherulesfortheFund.Theydefinewhichactivitiesareeligibleand
howabatementistobemeasured,verifiedandreported. Arangeofmethodshavebeen
approvedforallsectorsoftheeconomyincludingflaringmethanegasatlandfills,increasingsoil
carbon,upgradingequipmenttoimproveenergyefficiencyandregeneratingnativevegetation.
AllmethodsmustcomplywithOffsetsIntegrityStandardssetoutinlegislation.Thesestandards
ensureonlygenuineemissionsreductionscanbecreditedandthatmethodsusedwithinthe
Fundare:
• Additional:Abatementisunlikelytooccurintheordinarycourseofevents.
• Measureableandverifiable:Abatementmustbeabletobemeasuredandverified.
• Eligible:EmissionsreductionscreditedmustbeabletobecountedtowardsAustralia’s
climatechangetargetsandnotbeinconsistentwiththecarbonaccountingpractices
usedwithintheAustralianGreenhouseGasInventoryreporting.
• Evidencebase:Methodsmustbesupportedbyclearandconvincingevidence,
statisticallydefensibleandsupportedbyrelevantscientificresultspublishedinpeer-
reviewedliterature.
• Material:Projectabatementandrelatedsignificantemissionsshouldbeaccountedfor.
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• Conservative:Estimates,assumptionandprojectionsusedinthemethodshouldbe
conservative.
Onceapprovedandimplemented,themethodscanbeusedtogenerateAustralianCarbon
CreditUnits(ACCUs).OneACCUequatestoanemissionavoidanceorsequestrationofone
tonneofcarbondioxideequivalent(CO2-e)andcanbesoldtotheAustraliangovernmentorina
secondarymarkettogenerateincome.ToensureanyACCUspurchasedbytheAustralian
governmentarenotoffsetbysignificantincreasesabovebusiness–as-usuallevelsinemissions
elsewhereintheeconomy,theERFalsodevelopedasafeguardingmechanism.Underthe
safeguardmechanism,facilitieswithdirectemissionsinexcessof100,000tCO2-eperyearare
requiredtokeeptheirnetemissionsatorbelowabaselineleveldefinedbytheAustralianClean
EnergyRegulator(CER).SuchfacilitiescansurrenderACCUstheyhavegeneratedorpurchased
fromothers(excludingACCUspurchasedbytheAustraliangovernment)tooffsetemissionsover
theestablishedbaselinevalues.
Itisarequirementforasuccessfulprojectthatanysequesteredcarbonmustremainoutofthe
atmosphereforthedurationofthepermanenceperiodwhich,canbeeitherfor100or25years.
Ifaperiodof25yearsisselected,a20%discountisappliedtothenetabatementinorderto
calculatethenumberofACCUsthataprojectcanbeawarded.
AlistofthevariousmethodsavailabletoindividualsororganisationsundertheERFisaccessible
(www.environment.gov.au/climate-change/emissions-reduction-fund/methods)aswellaslinks
todocumentswithdetailsofhowtheyaretobeimplemented.Amongstthesemethods,two
soilcarbonsequestrationmethodsexist:
• Thefirstmethod,"Sequesteringcarboninsoilsingrazingsystems"isbasedonthedirect
measurementofchangesinsoilorganiccarbonstocksobtainedthroughthecollection
andanalysisofsoilsamplesovertime.
• Thesecondmethod,"Estimatingsequestrationofcarboninsoilusingdefaultvalues"is
basedontheuseofdefaultratesofsoilcarbonchangepredictedusingsimulation
resultsobtainedbyapplyingtheFullCarbonAccountingModel(FullCAM)modelling
systemdevelopedforandusedwithintheAustralianNationalGreenhouseGas
Inventory(RichardsandEvans2004;SkjemstadandSpouncer2003).
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Commontobothsoilcarbonmethodsarethedefinitionsofaproject,aprojectareaandcarbon
estimationareas(CEAs)(Figure1).Aprojectisdefinedasasetofactivitiesthatareadditionalto
thebusiness-as-usualconditionandareimplementedtoavoidgreenhousegasemissionsor
sequestercarbon.Theprojectareadefinesthespatialextentonwhichanoffsetsprojectis
carriedout.ACEAdefinestheareaoverwhichchangesinsoilcarbonstockswillbemeasured
ormodelledinresponsetotheappliednewmanagementpractices.MultipleCEAsmayexist
withinaprojectarea.TheprojectareaandCEAboundariesdonotneedtoberectangular,nor
dotheyneedtobecontiguous.Anexclusionzoneislandintheprojectareawherethenew
managementpracticesarenotimplementedandmayincludelandthatisnotusedforprimary
productionsuchasaresidentialbuildingandimmediatesurrounds.Accuratedefinitionof
boundariesandtotalareaencompassedwithineachCEAandexclusionzonesarerequired.
Figure1.Schematicrepresentationoftherelationshipbetweenlandtitleboundary,projectareaandcarbonestimationareas.
Method1:Sequesteringcarboninsoilsingrazingsystems
The“Sequesteringcarboninsoilsingrazingsystems”wasthefirstsoilcarbonmethod
developedforuseintheERF.Themethodwasdesignedtoquantifythemagnitudeand
certaintyofsoilcarbonchangewithinCEAsofanysize,andassumedthatnopriorinformation
pertainingtothespatialvariationinsoilcarbonstocksacrosstheCEAwasavailable.Underthis
method,aprojectproponentmeasuresbaselinesoilcarbonstockstoaminimumdepthof30
cm,implementsnewmanagementactivitiesthatwouldnothaveoccurredunderabusiness-as-
usualconditionandmeasuresfuturesoilcarbonstocksatnominatedintervalsthroughtimefor
eachCEAincludedinaproject.Aprojectproponentisapersonororganisationwhoislegally
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responsiblefortheERFprojectandhasthelegalrighttocarryouttheprojectandreceive
AustralianCarbonCreditUnits(ACCUs)generatedbythatproject.Asummaryofthemain
aspectsofthismethodologyfollows.Moredetailedpresentationsoftherequirements,
guidelinesandcalculationsrelatedtosamplingdesign,soilanalysisandderivationofcarbon
stocksforthismethod,aswellasanExcelbasedcalculatortofacilitatecalculationsofthe
temporalsoilcarbonstockchanges,canbefoundatwww.environment.gov.au/climate-
change/emissions-reduction-fund/methods/sequestering-carbon-in-soils.
Samplingdesign
Themethodusesastratifiedsimplerandomsamplingdesign(Figure2)inwhichaCEAisdivided
intoequalareastrata(n=9forFigure2).Soilsamplesrandomlylocatedwithinthestrataare
combinedtoformcompositesamples.Eachcompositesamplecomprisesonesamplefromeach
stratum.TheCEAisrepeatedlysampledthroughtime(t0,t1,…,tn).Thestratificationand
compositingacrossstrataiscompletedtoreducetheimpactofspatialvariationinsoilcarbon
stockswithintheCEAontheminimumdetectabletemporalchangeinsoilcarbonstock.A
minimumofthreestrataandthreecompositesamplesforaCEAisdefinedforthemethod;
however,itisrecommendedthatthenumberofstrataandcompositesareincreasedtothe
maximumthatcanbeaffordedtoensurethat:
• thecompositesamplesarerepresentativeoftheCEA,
• thevariancebetweencompositesamplescollectedatanyindividualtimeis
reduced,andtherefore
• theabilitytodetecttemporalchangeinsoilcarbonstocksisincreased.
Althoughthestratificationmustremainfixedoncethebaselinesamplinghasbeencompleted,
thenumberofcompositesamplescollectedcanbeincreasedordecreasedinsubsequent
samplingeventstooptimisethedesiredbalancebetweensamplingcostandminimum
detectablechange.
Samplecollection,processingandanalysisofsoils
Thecollectionofsoilsamplesistooccurusingcoringdeviceswithaminimuminternaldiameter
of4cm.TobeconsistentwiththeAustralianNationalinventoryReport(NIR)andIPCC
recommendations(Penmanetal.2003;Richards2001)thecollectionofsoiltoaminimum
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depthof30cmwasadopted;however,proponentsmaynominatetocollectadditionalsoilto
depths>30cm.Wheresoiltodepths>30cmiscollected,the0-30cmand>30cmsoilsamples
mustbepreparedandanalysedseparatelyandtheirrespectivecarbonstocksreported
separatelytoallowconsistencywithNIRpractices(http://www.environment.gov.au/climate-
change/greenhouse-gas-measurement/publications#national).Processingofcollectedsamples
includesair-drying,weighing,crushing,sieving,mixingandsub-samplingofthecollected
compositesamplesforanalysisoforganiccarbonandwatercontent(Figure3).
Figure2.Samplingdesigndefinedforthe“Sequesteringcarboninsoilsingrazingsystems”ERFmethodologywhereaCEAwasdividedinto9equalareastrataandthreecompositesoilsampleswerecollectedacrossthestrataduringeachtemporalsoilsamplingevent.
Determiningsoilcarbonstock,equivalentmassandequivalentmasssoil
carbonstock
UsingthedataidentifiedinFigure3andthevolumeofsoilsampled,themassofsoilcollected
fromeachlayer(Equation[1])andthestockoforganiccarbonpresentineachlayeroftheCEA
(Equation[2])arecalculated.Anequivalentsoilmasscorrespondingtothe10thdecileofallsoil
massesobtainedduringthebaselinesamplingisdefinedandallcarbonstockvalues(baseline
valuesandthosederivedforsubsequentsamplingevents)areadjustedtoprovidethemassof
carbonassociatedwiththeequivalentmassofsoil(Equation[3]).Theequivalentmass
approachwasadoptedtoaccountforvariationsthatmayoccurinsoilbulkdensityinresponse
tothealteredmanagementpracticesandtoalsoreducetheimpactoferrorthatmayoccur
duringsamplecollection(e.g.collecting30.2cminsteadof30.0cm).Wheretwosoillayersare
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sampled,thecalculationsbecomemorecomplex,butareallpresentedintheCarbonCredits
(CarbonFarmingInitiative)(SequesteringCarboninSoilsinGrazingSystems)Methodology
Determination2014(www.legislation.gov.au/Details/F2015C00582)
Figure3.Processingrequiredforcollectedsamples.
( ) ( ) ( )
3
SoilSoil Drybulk layermass density 100thicknessMg/ha Mg/m cm
= ´ ´ [1]
( ) ( ) ( ) ( ) ( )
3
Soilorganic SoilWaterSoilorganic Drybulk Proportionalcarbon layer1 contentcarbonstock density 1 massof 0.10content thickness gravelg/gMgC/ha Mg/mmgC/g cm
é ùæ ö æ öê úç ÷ ç ÷+= ´ ´ ´ ´ - ´ê úç ÷ ç ÷ê ú è øè øê úë û
[2]
( ) ( )
( )
( )
EquivalentsoilmassforthelayersampledEquivalentsoil SoilorganiccarbonMg/hamassorganic stockintheentrie
carbonstock soillayer SoilmassforthelayersampledMgC/ha MgC/ha Mg/ha
= ´ [3]
Quantifyingthetemporalchangesinequivalentmasssoilcarbonstock
Twoapproachesweredevelopedtoquantifythetemporalchangeinequivalentsoilmass
carbonstocks.Afterthebaselineandt1samplingeventsoccurred,aonetailedt-testassuming
unequalvarianceacrosstimeisusedtodefinethecarbonstockchangeassociatedwitha60%
probabilityofexceedance.Sinceitisdifficulttobeconfidentthatthetemporalchangein
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carbonstockmeasuredbetweentwopointsintimereflectsatruetemporaltrend,thechangein
soilcarbonstockatt1isdiscountedto50%ofthecalculatedchange.Oncethreeormore
temporalmeasurementsofequivalentmasssoilcarbonstocksarecompleted,aregression
approachisusedtodefinetherateofequivalentsoilmasscarbonstockchange(Figure4).In
thisapproach,themagnitudeandstandarderroroftheslopeoftheregressionlineobtainedfor
equivalentsoilmasscarbonstockexpressedasafunctionofthedurationoftheprojectareais
calculated.Thesevaluesareusedtodefinetheslope(annualchangeinequivalentsoilmass
carbonstock)associatedwitha60%probabilityofexceedance,whichisthenmultipliedbythe
numberofyearstheprojecthasbeenrunningandtheareaoftheCEA,todefinetheamountof
carbonsequestrationthathasoccurred.Themethodalsotakesintoaccountanychangesin
emissionsofmethaneornitrousoxideinresponsetothealteredmanagementpracticesand
awardsACCUsonthebasisofthenetgreenhousegasbalance(i.e.CO2-eassociatedwiththe
carbonsequesteredminustheCO2-eassociatedwithanyenhancedemissionofother
greenhousegases).
Figure4.Exampleoftheapproachusedtoquantifyequivalentmasssoilcarbonstockchangeusingtheregressionapproach.(a)ShowstheresultsobtainedfromtemporalmeasurementsofequivalentsoilmasscarbonstockswithinaCEAandthefittedregressionlineanditsassociatedstatistics.(b)Indicateshowthemagnitudeandstandarderroroftheslopeoftheregressionequationdefinedin(a)canbeusedtodefinethecumulativeprobabilityofexceedingaparticularrateofchangeofequivalentsoilmasscarbonstock.
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Currentdevelopmentswithinthedirectmeasurementmethod
Fromtheonsetofthedevelopmentofthismethoditwasidentifiedthatthesamplingdesign
maynotprovidethemostefficientapproachtoquantifythemagnitudeandcertaintyofcarbon
stockswithinaCEA.However,itwasintendedtoprovideanapproachthatcouldbe
implementeduniversally.TheDepartmentoftheEnvironmentandEnergyisdevelopinganew
ERFmethod,drawingonlessonslearnedfromimplementationoftheexistingmethod.
Thenewmethodwillinclude:
• newsampledesignapproachesthatusepriorspatialinformation(e.g.soilmaps,yield
maps,elevation,etc.)todivideaCEAintospatialstratathatdonothavetobeequalin
sizeandcontainmorehomogenoussoilconditions,
• landmanagementactivitiesassociatedwithcropping,grazingandmixedsystemsand
horticultural,and
• additionalapproachestoquantifyingtheorganiccarboncontentofsoilsincluding
varioussensors(e.g.visible-nearinfraredormid-infraredsensors)
Method2:Estimatingcarbonsequestrationinsoilwithdefault
vales
InthesecondmethodcurrentlyavailableforlandholderstogenerateACCUs,threeprojecttypes
thatcanreceiveACCUshavebeendefined:sustainableintensification,stubbleretentionand
conversiontopastures.Eligiblelandsandassociateddefaultratesofsoilcarbonsequestration
associatedwitheachprojecttypeweredefinedusinganupdatedversionofFullCAMandits
associateddatatablesthatwereusedtoprepareAustralia’s2015submissiontotheUnited
NationsFrameworkConventiononClimateChange(UNFCCC).Thisapproachusedamethod
consistentwiththe2006IPCCGuidelinesforNationalGreenhouseGasInventories(IPCC2006)in
conjunctionwithtechniquesdescribedinthe2013RevisedSupplementaryMethodsandGood
PracticeGuidanceforArisingfromtheKyotoProtocol(IPCC,2014).Amappingtoolisavailable
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forprojectproponentstocompletethetaskofdefiningwhetherapotentialprojectareaandits
CEAsresidewithineligiblelandsandifsowhatthedefaultratesofsoilcarbonsequestration
are.
Theareathatwasusedforsimulation(totaling34millionhectares)intheFullCAMwas
croplandsasidentifiedintheABARESCatchmentScaleLandUseofAustralia2014(version5)
whichwasprovidedbytheDepartmentofAgricultureatthemappingscaleof1:25000to1:250
000(http://data.daff.gov.au).Foreachofthethreeprojecttypes(sustainableintensification,
conversionfromcontinuouscroppingtocontinuouspastureandstubbleretention)changes
weremadetotheNationalInventorySystemdatabasetoreflectthedefinitionsofthe
simulations..Forexample,sustainableintensificationthefactualsimulationappliedtheyields
containedwithinthe2015database(businessasusual)andthecounter-factualapplieda20%
increaseinbiomass.
Forthefactualandcounter-factualsimulationsthesoilcarbonvalueafter25yearswas
aggregatedwithinanSA2(StatisticalArea–level2definedbytheAustralianBureauof
Statistics).Thedifferenceinsoilcarbonvaluesbetweenthefactualandcounter-factual
simulationswasthendividedbythenumberofhectaressimulatedandthe25yearswithina
givenSA2togenerateanaveragesoilcarbonstockchangeperhectareperyear.Thisvaluewas
thenassignedtotheSA2.
AhistogramoftheresultingsoilcarbonperhectareperyearvalueforeachSA2wasgenerated
todeterminetheJenksNaturalBreaksinthedatatoenableathreeclassregionalisationofthe
sequestrationvalues.Thethreeclassesweredefinedasfollows.
• MarginalBenefit-marginaldifferencebetweenthefactualandcounter-factualscenarioswasobservedonaperhectareperyearbasisafter25yearsattheSA2scale.Theclasswasdefinedattheboundaryofthefirstnaturalbreak(Jenks)inthehistogram.
• SomeBenefit–theclassfallingbetweenthefirstnaturalbreak(Jenks)inthehistogramandthe40thpercentileofthetailofthehistogram
• MoreBenefit–theremainderofthescenarioresults.
TheresultantratesofsoilcarbonsequestrationexpressedintCO2-eha-1y-1foreachclasswithin
eachprojecttypearegiveninTable1.Anexampleofthemapsderivedtodefineeligibilityand
sequestrationratefortheSustainableintensificationprojecttypeisshowninFigure5.
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Table1.Defaultvaluesforsoilcarbonsequestrationdefinedforeachofthethreeprojecttypes
ProjectTypeSequestrationvalue(tCO2-eha-1year-1)
Marginalbenefit Somebenefit Morebenefit
Sustainableintensification 0.11 0.59 1.65
Stubbleretention 0.07 0.29 0.73
Conversiontopasture 0.22 0.44 0.84
Figure5.Delineationofnon-eligibleandeligiblelandsforSustainableintensificationprojectsandtheareasassociatedwitheachofthethreelevelsofsoilcarbonsequestrationbenefitpredictedusingthesoilcarboncomponentoftheFullCAMsimulationmodel.
ThelandareatobeincludedinaprojectmustbestratifiedintooneormoreCEAs,andasingle
projecttypeandassociatedmanagementactivitymustbespecifiedforeachCEA.Itispossible
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toallocatedifferentprojecttypestodifferentCEAswithinasingleproject.Delineationofthe
projectandCEAboundariesaswellasprojecttypesandmanagementactivitiestobeapplied,
mustaccompanytherequestforprojectapprovalsoanassessmentofeligibilitycanbe
completed.
Eachprojecttypehasspecificconditionsandactivitiesthatmustbesatisfiedandimplemented,
respectively,forasequestrationprojecttobeapprovedandACCUsawarded.Theconditions
andactivitiesareoutlinedindetailinaseriesofdocumentsthatcanbefoundonthewebsite
describingthismethod(www.environment.gov.au/climate-change/emissions-reduction-
fund/methods/sequestration-carbon-modelled-abatement-estimates).Inthenextsectionsa
summaryofsomeofthemainpointsassociatedwitheachprojecttypeisprovided;however,
projectproponentsneedtoconsulttheofficialdocumentstogainafullunderstandingof
methodrequirements.
Sustainableintensification
Sustainableintensificationprojectscanbeappliedtocropping,pastureandmixedagricultural
systems,andmustincludetheapplicationofanytwoofthefollowingfouractivities:nutrient
management,introducingirrigation,managingsoilacidityorpasturerenovation.Ifcarriedout
oncroppinglands,itisaprerequisiteofthisprojecttypethatallresidues(stubble)mustbe
retainedwithintheCEA.
Nutrientmanagement
NutrientmanagementmustdemonstratethatthelandwithintheCEAhasamaterialdeficiency
(achieves<70%ofwaterlimitedyieldpotential)anditwaslikelytohavebeendeficientin
nutrientsinatleastfourofthefiveyearsofthebaselineemissionperiod.Themethodrequires
soiltestingtoidentifynutrientdeficiencies,provisionofwrittenadvicefromaqualifiedperson
(formaltraininginsoilhealthandplantnutrition)astohowtorectifynutrientdeficiencies,
constructionofanutrientbudgetandprojectnutrientmanagementplan,whichmustbe
reviewedandrevisedasnecessaryeverythreeyears.
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Managingacidity
ThisactivitycanbeappliedtolandswithanaveragepH<5.5inthesurface0-10cmsoillayeror
<4.8insubsoils(depths>10cm).Alimeapplicationsstrategydefiningrate,source,timingand
placementmustbedevelopedwithaqualifiedpersonandbeofasufficientmagnitudetobring
theaveragesoilpHtoavalueof5.5-6.0withinfiveyearswithaminimumapplicationrateof1.0
Mgha-1inthefirstyearoftheproject.RetestingofsoilpHmustoccuratleastonceeveryfive
yearsandadditionallimemustbeappliedifrequiredtomaintainthesoilpHintheCEAwithin
therangeof5.5-6.0.
Irrigation
InthetypicallywaterlimitedagriculturalproductionenvironmentsofAustralia,applicationof
additionalwaterthroughirrigationhasahighpotentialtoenhanceplantgrowthandtheinput
ofcarbontosoils.Soilcarbondecompositionrateswouldalsobeexpectedtoincrease,butonly
duringtheplantperiodofactiveplantgrowth.Thesoilcarbonsequestrationvaluesappliedin
themethodwerederivedfrommodellingastheneteffectoftheincreasedplantinputsand
decompositionlosses.Inthismethod,proponentsarerequiredtodemonstratethatthewater
usedisadditionaltothatusedpriortocommencingtheprojectandhasbeensourcedfrom
eithernewentitlementsorimprovedefficiencies.Insomeinstances,ifaproponentsources
waterbysecuringnewlyacquiredwaterfromanin-streamwaterorgroundwateraccess
entitlementsapotentialcarbonleakageriskarises.Thisisinresponsetoareallocationofwater
fromoneareasoflandtoanotherwherecarbonmayhavebeensequesteredontheprevious
landduetotheallocationofwater.Asthemagnitudeofthecarbonleakageriskisdifficultto
quantifyandthelikelihoodofoccurrencecanvaryconsiderablyonthecatchmentinwhichthe
projectisoperatingthenetsoilcarbonsequestrationratedefinedbythemodellingexerciseis
discountedby50%.
Pasturerenovation
Thepasturerenovationactivityonlyappliestolandsthathavebeenunderpastureforatleast
12monthspriortoinitiatingarenovationeventandmustthenstayunderpastureproduction
forthedurationofthepermanenceperiod.Itisarequirementthattheprojectproponentcan
demonstratetherenovationeventoccurred(e.g.throughfinancialrecords).Forpasture
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renovationtoincreasesoilcarbonstocks,thepasturemustsuccessfullyre-establishfollowing
renovation.Asuccessfulrenovationeventisconsideredasonewhere>70%soilcoveris
achievedwithin12monthsoftherenovationevent.Renovatedpasturesthatmeetthis
requirementwillbeeligibletoreceiveACCUs,whilethosethatdonotwillbeconsideredtohave
failedandwillnotbeeligibletoreceiveACCUs.
Retentionofcropresidues
Thisprojecttypecanonlybeappliedtolandundercropswhereatleast30%ofcropsurface
residues(stubbles)wereremovedthroughburning,bailingorgrazingineachofthe5most
recentyearsthatcropsweregrownpriortotheprojectbeinginitiated.Projectproponentscan
applyforanexceptionfromthisconditionforuptooneyear,withinthefiveyearbaseline
period,ifcropfailureoccurredanditwasnotpossibleorviabletoremovethestubbleundera
businessasusualscenario.TobeeligibleforACCUs,allburning,balingorgrazingofcrop
stubblesmustceasewithintheCEAforfouroutofeveryfiveyears,whichisconsistentwiththe
approachtakeninthemodellingexerciseusedtodefinethedefaultvalues.
Conversiontocontinuouspasture
Theconversiontocontinuouspastureprojecttyperecognisesthatsoilcarbonlevelsaretypically
higherunderpasturethancropmanagementpractices.Thistypeofactivitycanonlybe
undertakenwhereaproponentcandemonstratethatthelandwithaCEAwascontinuously
croppedandnotunderpastureatanypointwithinthefiveyearbaselineemissionsperiodprior
toinitiatingtheconversionandtheproject.Theestablishmentofthenewpasturemustachieve
aground-coverof>70%within12monthsandthelandmustremainunderpastureforthe
durationofthepermanenceperiod.
Calculatingtheamountofcarbonsequesteredwithinaproject
Providedaprojectmeetsallitsreportingobligationsandremainseligible,theamountofcarbon
sequesteredisdefinedbymultiplyingthedurationoverwhichtheprojecthasrunbythe
respectiverateofcarbonsequestration(includingdiscounts)providedinTable1.
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Calculatingnetabatementforbothcarbonsequestration
methods
Implementingasoilcarbonsequestrationprojectusingeitherofthemethodsdescribedmay
alteremissionsofmethane(CH4)and/ornitrousoxide(N2O)(Table2).ChangesinCH4andN2O
emissionsmustbetakenintoaccountinadditiontotheamountofcarbonsequesteredtoderive
thetotalnetabatementprovidedbyaproject.Foreachofthemanagementactivitieseligible
underthetwomethods,thenetabatementiscalculatedbyconsideringeachofthegases
identifiedinTable2.Itisimportanttonotethatcalculationofstocksoremissionsassociated
withboththebaselineandprojectactivitiesarerequiredanditisthedifferencebetweenthese
thatisusedtodefinethenetabatementwhenundertakingtheproject.Forexample,where
croppinglandsareconvertedtopastureandgrazedbyruminantlivestock,the
measured/modelledchangeinsoilcarbonstockmustbeamendedtoaccountfor:
1. AnyreductionsinN2Oassociatedwiththecropresidues,
2. AnychangesinN2OandCO2associatedwithchangesintheratesoffertiliser
application,and
3. AnyCH4andN2Oemissionsderivedfromthelivestock.
Therequiredcalculationsareprovidedinthemethodreferencematerialsonthewebsites
providedearlierinthisdocument.
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Table2.Greenhousegasesrequiredtobeincludedinnetabatementcalculationsforthevariouspotentialagriculturalmanagementactivitiesthatcanbeimplementedincarbonsequestrationprojects.
Carbonpooloremissionsource
Greenhousegas
Include/exclude Justificationandprocessforinclusion
Soilorganiccarbon
CO2 Include(containedwithinthedefaultsequestrationvalues)
Thisistheprimaryemissionsinkassociatewithsoilcarbonsequestrationprojects.
Livestock N2OCH4
Include Emissionsassociatedwithentericfermentation,dungandurinechangewithincreasesordecreasesinstockingrates.Impactsoffeedqualityareexcluded.NGGIemissionfactorsaretobeused.
Syntheticfertiliser
CO2N2O
Include ApplicationofsyntheticnitrogenfertilisersresultinemissionsofN2O,andinthecaseofureaalsoCO2.NGGIemissionfactorsaretobeused.
Non-syntheticorganicbasedfertilisers
CO2N2OCH4
Exclude Nonsyntheticfertilisersarederivedfromwastestreams.NoadditionalemissionsarerequiredtobeaccountedforsinceemissionsfromwithinaCEAtowhichtheyhavebeenappliedwouldbenogreaterthanwouldhaveoccurredhadthematerialsnotbeenapplied.
Agriculturallime
CO2 Include ApplicationofagriculturelimehasthepotentialtoemitCO2ascarbonatesreactwiththesoiltoneutraliseacidity.NGGIemissionfactorsaretobeused.
Irrigationenergy
CO2N2OCH4
Include Irrigatingpreviouslynon-irrigatedareasmayinvolveanincreaseinemissionsduetotheconsumptionofdieselfuelorelectricityandmustbeaccountedfor.NGGIemissionfactorsaretobeused.
Residues-decomposition
N2O Include RetentionofresiduesfromcorpswillresultintheemissionofN2Owhentheydecompose.NGGIemissionfactorsaretobeused.
Residues-burning
CO2N2OCH4
ExcludeCO2IncludeN2OandCH4
AnychangesinthequantityofresiduecarbonnotgoingtoCO2willbereflectedinthesequesteredcarbonwithinthesoil.NetchangesinN2OandCH4emissionsduetotheremovalofburninginprogressingfromthebaselinetoprojectconditionsneedtobeaccountedfor.NIRemissionfactorsaretobeused.
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References
Penman J, Gytarsky M, et al. (2003) Good Practice Guidance for Land use, Land-use change and Forestry.
Richards G (2001) The FullCam carbon accounting model: development, calibration and implementation for the National Carbon Accounting System. National Carbon Accounting System Technical Report No. 28.
Richards G, Evans D (2004) Development of a carbon accounting model (FullCAM v1.0) for the Australian continent. Australian Forestry 67, 277-283.
Skjemstad JO, Spouncer L (2003) Integrated soils modelling for the national carbon accounting system. Estimating changes in soil carbon resulting from changes in land use. National Carbon Accounting System Technical Report No. 36.
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