Energy use and greenhouse gas emissions from turf management of two Swedish golf courses

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ContentslistsavailableatScienceDirect

Urban

Forestry

&

Urban

Greening

jo u r n al ho me p a g e :w w w . e l s e v i e r . c o m / l o c a t e / u f u g

Energy

use

and

greenhouse

gas

emissions

from

turf

management

of

two

Swedish

golf

courses

Pernilla

Tidåker

a,∗

_,

_Therese

_Wesström

b

_,

_Thomas

_Kätterer

c

a_Swedish_Institute_of_Agricultural_and_{Environmental}_Engineering,_Box_7033,₇₅₀₀₇_Uppsala,_Sweden b_South_Pole_Group,_Waterfront_Building,_{Klarabergsviadukten}_63,₁₀₁₂₃_Stockholm,_Sweden c_Swedish_University_of_Agricultural_Sciences,_Department_of_Ecology,_Box_7044,₇₅₀₀₇_Uppsala,_Sweden

a

r

t

i

c

l

e

i

n

f

o

Articlehistory: Received1July2016

Receivedinrevisedform12October2016 Accepted15November2016

Availableonline18November2016 Keywords:

Carbonfootprint Golf

LCA

Lifecycleassessment Turfmaintenance

a

b

s

t

r

a

c

t

Turfmanagementongolfcoursesentailsfrequentmaintenanceactivities,suchasmowing,irrigation andfertilisation,andreliesonpurchasedinputsforoptimalperformanceandaestheticquality.Using lifecycleassessment(LCA)methodology,thisstudyevaluatedenergyuseandgreenhousegas(GHG) emissionsfrommanagementoftwoSwedishgolfcourses,dividedintogreen,tee,fairwayandrough, andidentiﬁedoptionsforimprovedmanagement.EnergyuseandGHGemissionsperunitareawere highestforgreens,followedbytees,fairwaysandroughs.However,whenconsideringtheentiregolf course,bothenergyuseandGHGemissionsweremainlyrelatedtofairwayandroughmaintenancedue totheirlargerarea.EmissionsofGHGforthetwogolfcourseswere1.0and1.6MgCO2eha−1year−1

asanarea-weightedaverage,whiletheenergyusewas14and19GJha−1_year−1_._Mowing_was_the_most

energy-consumingactivity,contributing21and27%oftheprimaryenergyuseforthetwogolfcourses.In addition,irrigationandmanufacturingofmineralfertiliserandmachineryresultedinconsiderableenergy use.Mowingandemissionsassociatedwithfertilisation(manufacturingofNfertiliserandsoilemissions ofN2Ooccurringafterapplication)contributedmosttoGHGemissions.Includingtheestimatedmean

annualsoilCsequestrationrateforfairwayandroughintheassessmentconsiderablyreducedthecarbon footprintforfairwayandturnedtheroughintoasinkforGHG.EmissionsofN2Ofromdecompositionof

grassclippingsmaybeapotentialhotspotforGHGemissions,butthehighspatialandtemporalvariability ofvaluesreportedintheliteraturemakesitdifficulttoestimatetheseemissionsforspecificmanagement regimes.LoweringtheapplicationrateofNmineralfertiliser,particularlyonfairways,shouldbeahigh priorityforgolfcoursestryingtoreducetheircarbonfootprint.However,measuresmustbeadaptedto theprevailingconditionsatthespecificgolfcourseandtherequirementssetbygolfers.

1. Introduction

Mitigationofclimatechangeandreducingthecurrent depen-dencyonfossilfuelsareinterlinkedchallengesshapingpoliciesin manysectors.TheEuropeanUnion(EU)hascommitteditselfto reducinggreenhousegas(GHG)emissions,increasingtheshareof renewableenergysupplyandimprovingenergyefﬁciency,allby 20%by2020(EuropeanCommission,2007),andthiscommitment requiresimmediatemeasuresinallsectorsofsociety.

Therearemorethan500golfcourses,occupyingapproximately 28,000ha, in Sweden (Statistics Sweden, 2013). Golf is associ-atedwithseveralbeneﬁts,e.g.itprovidesrecreationalvaluefor

∗ Correspondingauthor.

E-mailaddress:pernilla.tidaker@jti.se(P.Tidåker).

themany people who play the game, enhanceslocal biodiver-sitythroughextensivelymanagedroughsinareaswithintensively managedagriculture(TannerandGange,2005)andpromotessoil carbon(C)sequestration(QianandFollett,2002;SelhorstandLal, 2011).ManagedturfgrasssystemsachievesigniﬁcantlyhigherC sequestrationthan arable land and extensively managed grass-land (Qian and Follett, 2012). However, turfgrass maintenance ongolf courses is reliant onrepeated mowing, which requires fossil energy and releases GHG emissions to the atmosphere, mainlyascarbondioxide(CO2).Highturfgrassqualityalsorequires

othermaintenancepracticessuchasirrigation,fertilisation,vertical cutting,aerationand sanddressing,allwithassociated environ-mental impacts. Furthermore,nitrogen (N) fromfertilisers and plant residues enhancesnitriﬁcation and denitriﬁcation, which mayincreaseemissionsofnitrousoxide(N2O).Intensiveturfgrass

managementcombiningfrequent irrigationand fertilisationcan

http://dx.doi.org/10.1016/j.ufug.2016.11.009

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enhanceN2Olosses,particularlyifwaterisappliedimmediately

afterfertilisation(Guetal.,2015).However,soilN2Oproduction

is associatedwithhighvariability dependingon soilproperties andmanagement,whichposesagreatchallengewhenestimating N2Oemissions(Lietal.,2013).EmissionsofN2Oareparticularly

worrisomesinceN2Oisapotentgreenhousegaswithhighglobal

warmingpotential(GWP).TheGWPofacertaingasisameasureof howmuchheatistrappedintheatmosphererelativetotheamount ofheattrappedbyCO2overaspeciﬁctimeinterval(IPCC,2007).

TheconceptofGWPfordifferentGHGmakesitpossibletoaddthem togethertoobtaintotalGWPforanentiresystem.

EnergyuseandGHGemissionsarenotonlyassociatedwiththe maintenanceactivitiesperformedonthegolfcourses,sincethere arealsoindirectenvironmentalburdensrelatedtoproductionof purchasedinputssuchasmineralfertilisers,fuel,machineryand transportofsandusedfordressing.Lifecycleassessment(LCA)is acomprehensivemethodology addressingboth directand indi-rect energy use and emissions along the entire value chain in ordertoidentifyenvironmentalhotspots.LCAisacommonlyused standardisedprocedureforidentifyingopportunitiesforimproved environmentalperformance and providing decision supportfor stakeholdersinstrategicplanninganddevelopment(ISO,2006). Carbonfootprinting,asubsetofafullLCAincludingonlyGHG emis-sions causedby aproduct ora serviceduring itslifecycle and summarisedasCO2-equivalents,isattractingincreasinginterest

inthecontextofglobalwarmingmitigation(Röös,2013).

AnumberofstudieshaveevaluatedGHGemissionsfrompublic andprivatelawns(e.g.Townsend-SmallandCzimczik,2010;Zirkle etal.,2011;SelhorstandLal,2013;Kongetal.,2014;Guetal.,2015), whilefewerstudiesareavailableforgolfcourses.BartlettandJames (2011)modelledGHGemissionsfromtwogolfcoursesintheUK anddeterminedthebalancebetweensoilCsequestrationand emis-sionsfromturfmanagement.Theyassumedthesamesequestration rateforthetreelesscomponentsofthegolfcourses(green,tee, fair-wayandrough),independentoftimesinceconstruction,mowing frequencyandfertilisationrate,andfoundthatthemain contri-butiontoGHGemissionscamefrommowingandproductionof fertilisers.SelhorstandLal(2011)includedCreleasedueto differ-entmaintenancepractices,summarisedfortheentiregolfcourse, butexcludedGHGemissionsotherthanCO2.

Depending on the prevailing climatic and edaphic condi-tions,turfmanagementdiffersbetweenlocations.Inaddition,the differentplayableareasona golfcoursearemanagedwith dif-feringintensity.Inordertodevise andimplement efﬁcientand well-adjustedmeasuresfor sustainableturf management, more knowledgeisrequiredaboutcurrentenergyuseandGHG emis-sionsfromdifferentcomponentsofthegolfcourseandhowthese aredistributedamongdifferentmanagementactivities.

Theobjectiveofthepresentstudywasthustoevaluateenergy useandGHGemissionsfromannualmanagementoftwoSwedish golfcoursesdividedintogreen,tee,fairwayandrough,andidentify optionsforimprovedmanagement.Particularemphasiswasplaced onmaintenanceoperationsandpurchasedinputs.

2. Materialandmethods

LCAmethodologywasusedforevaluationofprimaryenergy useandGHGemissionsassociatedwithturfmanagementongolf coursesduringoneyear.EmissionsofGHGweresummarisedas CO2-equivalents(CO2e)accordingtoIPCC(2007),withatime

hori-zonof100years.Theresultswerepresentedbothperhectareand fortheentirecourses.

Informationonmanagementpractices wasobtainedthrough interviews with course managers of the golf courses. A brief descriptionofdifferentactivitiesperformedonthetwogolfcourses

Table1

Areaofthedifferentplayablecomponentsincludedinthestudy,basedon informa-tionprovidedbythegolfcoursemanagers.

Course Green(ha) Tee(ha) Fairway(ha) Mowedrough(ha) Total(ha)

Sigtuna 1.5 1.0 10 40 52.5

Uppsala 2.5 1.5 22 50 76

ispresentedbelow,whileamoredetaileddescriptioncanbefound inWesström(2015).

2.1. Descriptionofthegolfcoursesandtheirmanagement

Thegolfcoursesincludedinthestudyareparklandcourses sit-uatedineastern Sweden.Oneofthegolfclubsislocatedinthe countyofUppsalaandwasestablishedatitspresentsitein1964. Itcurrentlyconsistsofone18-holecourseandtwo9-holecourses, withatotalplayableareaof76ha(Table1).Theothergolfclubis locatedoutsidethetownSigtuna,inbetweenStockholmand Upp-sala.Ithasone18-holecourseconstructedintheendofthe1960s, one6-holecourseandfourpracticegreens.Thegolfcoursesare sur-roundedbyamosaiclandscapecharacterisedbyagriculturalland andforest.ThetotalplayableareasofthecoursesinSigtunaand Uppsalawere52.5and76ha,respectively(Table1).

The golf season is approximately 26 weeks in Uppsala and 28 weeksinSigtuna.Maintenance strategiesdifferconsiderably betweentheplayingareas,inordertoprovideoptimalperformance andaestheticqualityforeachspeciﬁcarea.

2.2. Applicationoffertiliser,pesticides,sandandwater

Theapplicationrateofmineralfertilisersvariesslightlybetween years.Sigtunafollowsaspeciﬁcfertiliserregimewheretheweekly fertilisationofgreensandteesispre-ordained.Here,weuseddata from2013,whichwasconsideredtobearepresentativeyear.At Uppsala,fertiliserapplicationisdeterminedbythecoursemanager andthedatausedinthisstudywererepresentativeofrecentyears. Fertilisersareappliedmanuallytogreensandteesonaregularbasis throughouttheseason.Fairwaysarefertilisedmechanicallyseveral timesayear,whileroughsdonotreceiveanymineralfertiliser.

Fungicidesandherbicidesareoccasionallyusedatbothcourses, whileinsecticidesarenotusedatall.TheroughinUppsalareceives herbicidesonceeveryotheryear.

Theirrigationfrequencyisdeterminedbyprecipitation.In gen-eral,greens,teesandfairwaysareirrigatedapproximatelythree timesperweek,whileroughsarenotirrigatedatall.Theirrigation waterusedinSigtunaispumpedfromanearbylakeanddistributed viaanundergroundpipesystem,complementedwithahosewhen necessary.InUppsala,thewaterispumpedfromanearbypondthat alsoreceivesdrainagewaterfromthecourse.Theamountsofwater appliedtothedifferentpartsofthecourseinthisstudywerebased onestimatesbythemanagers,sincenomeasureddatawere avail-able.Sandfordressingisappliedongreensandteesatbothsites, andonfairwaysinUppsala.Thissandistransported160kmto Upp-salaand50kmtoSigtuna.Theamountsofmineralfertiliser,sand andpesticidesappliedandthevolumeofwaterusedforirrigation arepresentedinTable2.

2.3. Mowingandothermaintenancepractices

GreensaremowedseventimesaweekatUppsalaandﬁvetosix timesaweekatSigtunaduringtheseason.Teesandfairwaysare mowedthreetimesaweekatbothsitesduringtheseason.Roughs aremowedonceaweekduringtheseason,usingarotarymower. Onallareas,seasonalmowingiscomplementedwithsome addi-tionaloff-seasonmowing.Thegrassclippingsfromgreensandtees

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Table2

Annualamountsofmineralfertilisers(N,PandK),sand,pesticides(activesubstance)andirrigationwaterappliedperhectaretodifferentpartsofthegolfcoursesinSigtuna andUppsala.

Site N(kg) P(kg) K(kg) Pesticide(kg) Sand(Mg) Irrigation(103_m3₎

Green Sigtuna 214 37 139 1.35 187 3.6 Uppsala 190 80 190 1.35 120 3.0 Tee Sigtuna 176 27 108 40 3.6 Uppsala 220 40 220 1.35 33 3.0 Fairway Sigtuna 89 12 40 0.39 1.8 Uppsala 160 40 160 0.64 30 1.4

arecollectedbythemoweratbothsitesandareeithercomposted orspreadoutonothergrass-coveredareas.Clippingsfromfairways androughsarenotcollected,butlefton-site.

Aerationisperformedwithdifferentfrequencyandmachinery ondifferentpartsofthegolfcourse.Deep-tineaerationandhole pipeaerationaremainlyusedongreensandtees.Verticuttingis performedongreensatboth sites,but onlyontees atSigtuna. Topdressingismostfrequentlyusedongreens.Theseasonal man-agementpracticesperformedaresummarisedinTable3.

InSigtuna,150Lofengineoiland160Lofhydraulicoilareused annuallyformaintenanceofthemachinery,whilethe correspond-ingvaluesinUppsalaare60and150L,respectively.

Meanfuelconsumptionfordifferentoperationsissummarised inTable4.Allmachinerywasassumedtousedieselexceptfora pedestrianmowerforgreensandawalk-behindaeratorfor aera-tionofgreensandtees,whichconsumedpetrol.Dataonmowing ofgreensand fairwaysin Uppsalawereobtainedfroma previ-ousstudyoffuelconsumptionpercycleofmaintenance onthe maingolfcourse(Caple,2008),whilethecoursemanagerprovided estimatesformowinginSigtuna.Nomeasurementswere avail-ableformowingtheroughinUppsalaandthereforetheestimated fuelconsumptionperoccasion(6Lha−1)atSigtunawasalsoused forUppsala.Fuelconsumptionforaerationwasbasedon assump-tionsmadebythegolfcoursemanagers.Thedifferenceinassumed fuelconsumptionwasduetodifferentmachinerybeingusedfor aeration.Dataonfuelconsumptionforverticuttinganddressing werebasedonmeasurements(Caple,2008).Sinceahigherrate ofsandwasappliedtoteesandfairwaysinUppsala,higherfuel consumptionperhectarewasassumedfortheseareascompared withdressingofthegreens,basedonestimatesmadebythecourse managers.

2.4. Systemboundaries

Thesystemstudiedincludedproductionofpurchased inputs (fertiliser,fuelandelectricity),transportofsand,production, main-tenanceandrepairofmachinery,andturfmanagementfordifferent activitiesaccordingtocurrentpracticesduringonerepresentative year(Fig.1).Fuelconsumption permaintenance cycleincluded travellingbetweencoursespartsforthemachineryinuse.

Thecontributionfromproductionandapplicationofherbicides andfungicideswasomittedintheassessment,sinceitcontributed lessthan1%tothetotalenergyuseandGHGemissions.Reseeding wasalsoomitted,sinceitscontributionwasconsiderednegligible. Constructionofthecourseswasnotincludedduetolackof infor-mationabouttheresourcesusedduringconstruction,as itwas performedmanydecadesago.

Aconsiderableamountofclippingsiseithercomposted,spread outdirectlyonothergrassedareasorlefton-siteaftermowing.The emissionsofN2Oassociatedwithturnoveroftheseclippingswere

consideredinthesensitivityanalysis,sincehighvariabilitycanbe expectedandnomeasurementswereavailable.Indirectemissions ofN2OcausedbyNlossesthroughvolatilisationandleachingwere

notaccountedfor,sincetheseemissionswereconsideredminor comparedwiththedirectemissionsofN2O.

Fig.1.Activitiesincludedinthestudycausingdirectandindirectenergyuseand GHGemissionswithinandoutsidethegolfcourses.

2.5. Generalassumptionsanddataused

DataonGHGemissionsfromfuelcombustionrelatingto trans-port and maintenance operations were taken fromGode et al. (2011) and included production, distribution and combustion. Onlyemissionsdataforstandarddieselwereused,althoughalso syntheticdieselwasusedforsomeapplications.Electricity con-sumptionforirrigationwasestimatedbythecoursemanagersto be0.45kWhm−3atUppsalaand0.5kWhm−3atSigtuna.Emissions datafor theSwedishaverageelectricity production weretaken fromGodeetal.(2011),assuminganelectricitymixprimarilybased onnuclearpowerandhydropower.Afactorof2.1wasusedfor convertingelectricityintoprimaryenergy,consideringa transfor-mationefﬁciencyof50%anddistributionlossesinthegrid.Inthe sensitivityanalysis,theimpactofelectricityproducedfrom nat-uralgaswasevaluatedasanalternativetoprevailingproduction conditionsinSweden.

Differentmachinesanddevicesareusedongolfcoursesforthe manymanagementoperationsperformed.Athoroughinventoryof allmachineryused,itsmaterialcomposition,annualuse,life-time etc.wasnotpossibleduetolackofsite-speciﬁcinformationfrom thegolfcourses.Instead,aroughestimatewasmadebyassuming thatenergyuseandGHGemissionsfrommanufacturing, mainte-nanceandrepairofmachinerycomprised17%ofthetotalenergy useandGHGemissionsfromallturfoperationsperformed.This estimatewasbasedonthedistributionbetweenmanufacturing andoperationphasescalculatedfor Swedishcropproductionin thesameregion(Tidåkeretal.,2016).Theengineoilandhydraulic oilusedwereassumedtobeincludedinthisestimate.

Dataonenergyuseforfertiliserproductionweretakenfrom BrentrupandPallière(2008),basedonaverageﬁguresfor Euro-peanproductionin2006,whiledataonGHGemissionsweretaken fromKooletal.(2012).Dataforureaammoniumnitratewere cho-sen,sincethefertiliserproductsusedcontainedamixtureofurea, ammoniumandnitrate.Theaveragedieselrequirementfor trans-portofsandwassetat0.4Lkm−1,assumingatruckandtrailerwith emptyreturntransport.

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Table3

FrequencyofannualmaintenancecyclesperformedondifferentpartsofthegolfcoursesinSigtunaandUppsala.

Site Mowing Aeration Verticutting Topdressing

Green Sigtuna 160 6 14 14 Uppsala 198 6 8 13 Tee Sigtuna 88 1 3 3 Uppsala 82 6 0 1 Fairway Sigtuna 88 2 0 0 Uppsala 82 3 0 1 Table4

Fuelconsumption(litresha−1_occasion−1₎_during_management_operations_on_different_parts_of_the_golf_courses_in_Sigtuna_and_Uppsala.

Mowing Aeration Verticutting Topdressing

Green Sigtuna 3.3 42 11 8.7 Uppsala 3.6a ₄₂ ₁₁ _8.7 Tee Sigtuna 8 42 11 8.7 Uppsala 10.5 21 18 Fairway Sigtuna 3 9 Uppsala 3.2b ₉ ₁₈

a_On_the_main_course,₁₈₈_mowing_operations_were_performed_using_a_pedestrian_mower_(3.6_L_petrol_ha−1_),_and₁₀_operations_were_performed_using_a_ride-on_mower

(7.1Ldieselha−1_).

b_Mean_fuel_consumption_included_the_assumption_that_half_the_mowing_regimes_were_performed_with_a_groomer_with_higher_diesel_use.

DirectemissionsofN2Ofromsoilswereestimatedusingthe

IPCCdefaultemissionsfactor(2006),whichis 1%ofthetotalN addedasmineralfertiliser.Inthesensitivityanalysis,thisemissions factorwasappliedtothegrassclippings.

3. Results

3.1. Energyuseperhectareofgreen,tee,fairwayandrough

Energyusewashighestforgreens,followedbyteesand fair-ways (Table5).Energyuseforgreen management wasroughly threetimeshigherperhectarethanforfairwaysonthesamegolf course.Thelowestenergyusewasassociatedwithmaintenance ofrough(7.6GJfor Sigtunaand 7.1GJfor Uppsala),which only includedmowingandmanufactureandmaintenanceofmachinery. Mowingwasthesinglemostenergy-consumingactivityperformed foralltypesofareas.However,thecontributionfrommowingper hectarewaslessthanhalfofallenergyuse(26–45%)associated withmaintenanceofgreen,teeandfairway,sinceirrigationand manufacturingofmineralfertiliserinparticularmadeimportant contributions.Forgreens,transportofsandaddedsigniﬁcantlyto thetotalenergyuse.

Energyuseformaintenanceoffairwayswasconsiderablyhigher forUppsala,whichwaslargelyexplainedbythehigherapplication rateofNfertiliserandsandtransportoveralongerdistance. 3.2. EmissionsofGHGperhectareofgreen,tee,fairwayandrough

EmissionsofGHGfrommaintenanceofonehectareofgreen were6.2MgCO2eforSigtunaand6.8MgforUppsala(Fig.2).Among

managementactivities,mowingcontributedmosttoGHG emis-sions(23%forSigtunaand27%forUppsala).AmajorsourceofGHG emissionswasassociatedwithmineralfertiliser(inparticularN), boththroughmanufacturing,inwhichCO2andN2Oisreleased,and

throughemissionsofN2Ofromsoilafterapplication.Intotal,

min-eralfertiliseraccountedfor38%oftheGHGemissionsatSigtuna and32%atUppsala.ForUppsala,thecontributionfromtransport ofsandwasalsoconsiderable.

EmissionsofGHGfromteesamountedto4.7and6.1MgCO2e

ha−1year−1forSigtunaandUppsala,respectively.Theseemissions weredominated bymowing(41 and39% forSigtuna and Upp-sala,respectively),followedbymanufacturingofmineralfertiliser, directsoilemissions(N2O)andirrigation.Manufacturingof

min-Fig.2. EmissionsofGHG(kgCO2eha−1year−1)dividedintodifferentmaintenance

activitiesforgreensatthegolfcoursesinSigtunaandUppsala.

Fig.3.EmissionsofGHG(MgCO2eha−1year−1)dividedintodifferentmaintenance

activitiesforfairwaysatthegolfcoursesinSigtunaandUppsala.

eralfertiliserandsoilemissionsofN2Oafterapplicationaccounted

for41%atbothsites.

EmissionsofGHGassociatedwithmaintenanceoffairways dif-feredgreatlybetweenthesitesandwere1.9MgCO2eha−1year−1

forSigtuna and3.1Mg CO2eha−1year−1 forUppsala(Fig.3).A

considerableshareoftheGHGemissionswasrelatedtomineral fertiliser,includingboththefertilisermanufacturingphaseandsoil

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Table5

Primaryenergyuse(GJha−1_year−1₎_split_into_different_maintenance_activities_for_green,_tee_and_fairway_at_the_golf_courses_in_Sigtuna_and_Uppsala.

Green Tee Fairway

Sigtuna Uppsala Sigtuna Uppsala Sigtuna Uppsala

Mowing 21 27 27 33 10 10 Irrigation 14 10 14 10 7 5 Verticutting 6 3 1 Aeration 9 9 1 5 1 1 Topdressing 5 4 1 1 1 Transportofsand 7 15 2 4 4 Fertilisation 0.4 0.4

Mineralfertiliserproduction 13 13 10 14 5 10

Productionofmachinery 6 7 5 7 2 2

Total 81 89 61 74 25 33

Table6

Relativecontributionofdifferentmaintenanceactivitiestototalprimaryenergyuse andGHGemissionsfortheentiregolfcoursesinSigtunaandUppsala.

Energyuse(%) GHG(%)

Sigtuna Uppsala Sigtuna Uppsala

Mowing 57 46 54 39 Irrigation 14 10 1 1 Verticutting 1 1 1 1 Aeration 3 4 3 3 Topdressing 1 2 1 1 Transportofsand 2 9 2 7

Productionofmineralfertiliser 11 20 16 24

Directsoilemissions 12 17

Productionofmachinery 11 9 10 7

Totalperha&year 100 100 100 100

emissionsofN2Ooccurringafterapplication.Intotal,emissions relating tofertilisationwere50% for Sigtuna and 58%for Upp-sala,whilethecorrespondingﬁguresformowingwere37and23%, respectively.

The contribution to GWP per hectare from maintenance of roughswas0.54MgCO2eforSigtunaand0.50MgCO2efor Upp-sala.Theonlyaspectsaccountedforweremowingandproduction ofmachinery.

3.3. EnergyuseandGHGemissionsfortheentiregolfcourses For the golf courses studied, the largest proportion of area wasoccupiedbyrough,followedbyfairway,greenandtee.The resultsperhectarewerethereforeconvertedtovaluesfortheentire courseinordertoobtaininformationonhowtotalenergyuseand GHGemissionsaredistributedbetweenthedifferentplayingareas andwhichactivitiestoprioritiseinordertoimprovetheoverall environmentalperformance.InTable6,energyuseandGHG emis-sionsaresplitintodifferentactivitiesexpressedfortheentiregolf courses,usingtheareaspresentedinTable1.

Mowingwasbyfarthesinglemostenergy-consumingactivity, andalsomadeamajorcontributiontoGWP(Table6).Fertilisation affectedbothenergy useandGHGemissions.EmissionsofGHG relatingtofertilisation(manufacturingand soilemissions)from Uppsalacontributedconsiderably(41%)duetothehigherN appli-cationrateonfairwaysandthehigherproportionoffairwaywithin thetotalarea.ThecorrespondingvalueforGHGemissionsrelated tofertilisationatSigtunawas28%.

Expressedasarea-weightedaverageperhectareandyearfor theentiregolfcourses,theenergyusewas14GJforSigtunaand 19GJforUppsala.ThecorrespondingcontributiontoGWPwas1.0 and1.6MgCO2e,respectively.

Greens constituted a minor proportion of the golf courses (approximately3%), butcontributeda considerablylargershare ofthetotalenergyuseandGHGemissions(14–17%)duetotheir intensivemanagement(Fig.4).

Fig.4. RelativecontributiontoprimaryenergyuseandGHGemissionssplitinto green,tee,fairwayandroughforthegolfcoursesinSigtunaandUppsala.

Thecontributiontoenergyuseand,inparticular,toGHGwas considerablyhigherforfairwaysthanitsshareofthetotal area withingolfcourses(19%oftheareaatSigtunaand29%atUppsala), whiletheextensivelymanagedroughmadeasigniﬁcantlylower contributionthanitsshareofthegolfcourses(76%oftheareaat Sigtunaand66%atUppsala).ForSigtuna,roughwasthearea asso-ciatedwiththehighestenergyuseandGHGemissions.ForUppsala, morethanhalfofallenergyuseandGHGemissionswasrelatedto fairwaymanagement.

3.4. Sensitivityanalysis

EmissionsofGHGfromelectricityproductionarestrongly inﬂu-encedbyitsorigin.Thelow carbonfootprintfromtheSwedish electricitymixreﬂectsitslargeshareofhydropowerandnuclear power,bothassociatedwithlowGHGemissions.Theassumption inthesensitivityanalysisthat theelectricity usedforirrigation wasproducedonthelong-termEuropeanmargin,i.e.considered tobeproducedfromnaturalgas,increasedtheGHGemissionson averageby10%atSigtunaand8%atUppsala.Thehighestrelative increasewasobtainedforfairwaysatSigtuna(Table7).

EmissionsofN2Owereaccountedforbyassumingthat1%ofthe

NappliedasfertiliserwasemittedasN2O N.However,grass

clip-pingsfromgolfcoursesurfacesareeitherremovedandcomposted, spreadonothersurfacesorlefton-site.Duringdecompositionof theseclippings,N2Owillbeemitted.Accordingtomodel

simula-tionsofN2Oemissionsfromurbanlawns,expectedN2O Nlosses

rangebetween0.75–3.57kgha−1year−1forlawnsfertilisedwith 0–89kgN,andrecyclingoflawnclippingshasbeenidentiﬁedas animportantsourceofN2Oemissions(Guetal.,2015).The

pro-poseddefaultemissionsfactorforN2O NaccordingtoIPCC(2006)

forcompostinginwindrowswithinfrequentturningformixing andaerationis1%.Thisiswithinthesameorderofmagnitudeas

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Table7

EmissionsofGHG(MgCO2eha−1)onchangingtheassumptionsasregardselectricitymix,N2Oemissionsfromdecompositionofgrassclippingsandsoilcarbonsequestration

inthesensitivityanalysis.

Green Fairway Rough

Sigtuna Uppsala Sigtuna Uppsala Sigtuna Uppsala

Originalsetting 6.2 6.8 1.9 3.1 0.5 0.5

Electricityfromnaturalgas 6.9 7.4 2.3 3.4

IncludingN2Ofromclippings 6.9 7.2 3.5 4.9 1.3 1.4

IncludingCsequestration 0.8 2.0 −0.6 −0.6

thevaluereportedforgardenwastecompostinginDanishstudies (Boldrinetal.,2011).Anemissionsfactorof1%wasusedinthe sen-sitivityanalysisinthepresentstudy,irrespectiveofhowthegrass clippingswerehandled.TheNcontentinclippings,information requiredforestimatingN2Oemissions,wasnotmeasuredwithin

this study. However, data on net primary production (NPP) of above-groundbiomassforthedifferentmanagementareasonthe golfcoursesinSigtunaandUppsalawereavailableinanotherstudy withinthesameresearchprogrammeestimatingNPPthrough fre-quentsamplingduringthegrowingseasonin2014(unpublished data).ThatstudyshowedthatNPPwassigniﬁcantlyloweringreens (4.5and2.7Mg drymatterha−1 in SigtunaandUppsala, respec-tively)thaninfairwaysandroughs,butdidnotdiffersigniﬁcantly betweenfairwaysandroughsandwasonaverage11.5Mgdry mat-terha−1 inSigtunaand12.5Mgha−1inUppsala.AccumulatedN uptakeinclippingswasassumedtocorrespondto3%ofNPP,which isa rather conservativeestimateoftheN concentrationin fre-quentlycutturfgrassclippings(e.g.KoppandGuillard,2002)andis consideredthelimitforachievingfunctioningandhealthylooking turfinSweden(Ericssonetal.,2012).Intheunfertilisedrough,the Nconcentrationinclippingswasassumedtobelower(1.5%ofNPP) duetolessfrequentcuttings,asalsoreportedformorematuregrass swardsinSweden(Kättereretal.,1998).AsshowninTable7, inclu-sionofN2Ofromdecompositionofclippingshadastrongimpact

onGHGemissionsfromfairwayandrough.

SoilorganicCstocksaregenerallyhigheringrasslandsoilthan inarablesoil(PoeplauandDon,2013).Sincethegolfcourses stud-iedherewereestablishedonarableland,whichprobablyhada historyofmixedfarming,itislikelythatCstocksintheturfhave increasedsinceestablishmentofthegolfcoursesabout50years ago.Thetopsoil(0–20cmdepth)inthefairwayandroughareas currentlycontainsabout80MgCha−1onaverageoverthetwo sites(unpublisheddata),whichis23%morethantheCcontentin mineralagriculturaltopsoilsintheregion(Andrénetal.,2008).If thisdifferenceinCstorageisattributedtoturfmanagementover50 years,soilsequestrationinfairwayandroughareaswouldamount to0.3MgCha−1year−1.ThusincludingsoilCsequestrationreduced theGHGemissionsfromfairwaysconsiderablyandturnedroughs intoasinkforGHG.

4. Discussion

EnergyuseandGHGemissionsperhectarewereconsiderably higherfromgreensandteesthanfromfairwaysand,in particu-lar,fromextensivelymanagedroughs(Table7).Forexample,GHG emissionsfromgreenswereabouttwo-andthree-foldhigherthan thosefromfairwaysatUppsalaandSigtuna,respectively.Bartlett and James (2011) reported similar differences between greens and fairwaysin theirstudy onturfmanagement at twoBritish golfcourses.EmissionsofGHGperhectarefromfairwaysat Sig-tunawereofthesamemagnitudeasreportedforBritishparkland courses,whileemissionsfromfairwaysatUppsalawereabout60% higher.EmissionsofGHGperhectarefromgreenswereslightly lowerthanreportedfortheBritishcourses,whileemissionsfrom roughsweremorethantwo-foldhigherintheBritishstudy.

How-ever,thereweresomeimportantdifferencesinthemaintenance activitiesperformedinthedifferentstudiesandintheprocesses includedwithinthesystemboundary.Dressing,transportofsand andproductionofmachinerywerenotincludedintheBritishstudy, whichexplainssomeofthedifferences.Moreover,theapplication rateofNmineralfertiliserandmowingfrequencywerehigherfor greens,teesandfairwaysontheSwedishgolfcoursesincludedin thisstudy.Ontheotherhand,theGHGemissionsfromtheBritish parklandroughweresigniﬁcantlyhigherduetoNfertiliser appli-cationandhighbasalrespiration(anaspectnotincludedinthis study).EmissionsofGHGassociatedwiththeplayingareas(tee, green,fairwayandrough)inthestudybyBartlettandJames(2011), whichamountedto1.7MgCO2eha−1year−1onaverage,were

sim-ilartothoseinUppsala(1.6MgCO2eha−1year−1)buthigherthan

thoseinSigtuna(1.0MgCO2eha−1year−1).However,as

empha-sisedabove,theGHGemissionsweredistributeddifferentlyamong thedifferentplayingcomponents,inparticularfortheroughs.

Mowingmadethesinglehighestcontributiontoenergyusefor allareas.Introducingelectriﬁedmachineryforsomemanagement operationswouldbeaneffectivemeasureforreducingfossilfuel dependencyandGHGemissionsfromgolfturfmanagement, pro-videdthatelectricityisproducedwithrenewablesourcesandalow carbonfootprint.

Anotherimportant contributor toboth energy useand GHG wasmineralfertiliser,inparticularN.MostGHGemissionswere relatedtomanufacturingofNmineralfertiliser,butN2Oemissions

occurringafterapplicationalsocontributedconsiderably.Sincethe ratherintensivelymanagedfairwaysconstitutealargepartofgolf courses,theenvironmentalfootprintfortheentiregolfcourseswas particularlydeterminedbymanagementofthefairways,especially forUppsala.TherewasamarkeddifferenceintheNrateusedon fairwaysatthetwosites.DetermininghowtheNapplicationrate couldbereducedonfairwayswhilemaintainingturfqualityisthus animportantstepinreducingtheenvironmentalburdenfromgolf courses.AssumingthatareductioninNapplicationratewouldalso reduceturfgrassgrowth,theneedformowing,andthustheenergy useandemissionsrelatedtomowing,woulddecrease.

IrrigationmadeanalmostnegligiblecontributiontoGHG emis-sionsduetothelowGHGemissionsassociatedwiththecurrent Swedishelectricitymix.Inregionswhereelectricityisproduced fromnaturalgas,thecontributionfromirrigationwouldincrease considerably,asshowninthesensitivityanalysis.Inregionswhere electricityisproducedfromcoal,thecarbonfootprintfrom elec-tricitywouldbeevenhigher.

Intensivemanagement,involvingirrigation,mowing, fertilisa-tionandrecyclingofgrassclippings,areallactivitiesassociated withN2Oemissions(Guetal.,2015).However,itisunclearhow

toaccountforN2Oemissionsfromgrassclippingsleftfor

decom-position,sincetheseemissionsexhibithightemporalandspatial variability.Theassumptioninthesensitivityanalysisthat1%of theNingrassclippingswasemittedasN2O Nstronglyaffected

theGHGemissionsfromturfmanagement.Handlingofgrass clip-pingsisthusapotentialhotspotwithinturfgrassmanagementthat needsfurtherexamination.Lietal.(2013)observedinconsistent responseswhengrassclippingswereaddedinturfgrasssystems,

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withsoilaerationconditionsasoneimportantfactorinﬂuencing theresults.ThegrassclippingsfromfairwaysinSigtunaand Upp-salawereestimatedtocontain345and375kgNha−1,respectively, whichmadeclippingsanimportantsourceofNintheturfgrass system.Guetal.(2015)advocaterecyclingofgrassclippingsasa meansofloweringtheNapplicationrate.Exploitingthefertiliser valueofrecycledclippingsindifferentconditionsandreducingthe applicationratesofmineralNfertilisationcouldbeaneffective managementoptionforreducingN2Oﬂuxesfromgolfcourses.

SoilCsequestrationisanimportantmeasuretooffsetGHG emis-sionsfromturfmanagement.AnassumedsoilCsequestrationrate of0.3Mgha−1year−1forfairwaysandroughsinthepresentstudy resultedinaconsiderablylowercarbonfootprintfortheUppsala course(0.5MgCO2e),whiletheGHGemissionsfromSigtunawere

totallyeliminated.InarecentSwedishstudy,frequentlycuturban lawnswerefoundtocontain55% moresoilCthansurrounding arablesoils(Poeplauetal.,2016).Perennialplantssuchas turf-grassgenerallyhavedenserrootsystemsthanannualcrops(Wang etal.,2014)androot-derivedCispreferentiallystabilisedinsoil (Kättereretal.,2011).Thisisthemainreasonwhyanincreased fre-quencyofperennialforagesincroprotations(Bolinderetal.,2010) oralandusechangefromarabletopermanentgrasslandleadsto soilCsequestration(Kättereretal.,2008).High Csequestration ratesfollowingconversionoffarmlandtogolfcourseshavebeen reportedinseveralstudies.Forexample,SelhorstandLal(2011) reportedsequestrationratesas highas 0.44Mg C (correspond-ingto1.6MgCO2e)ha−1year−1 onaverageover aperiodof 91

yearsinfairwayand roughareasonfarmlandconverted togolf coursesinOhio.Evenhighersequestrationrates(0.9and1.0Mg Cha−1year−1)werereportedbyQianandFollett(2002)for fair-waysand greenson16 golfcoursesintheUSA.However,their studywasmoreshort-term(25–30years)andthissequestration ratewillprobablynotpersistinalongertimeperspective,sincesoil Csequestrationratesareknowntodecreasewithtimeuntilanew steadystatesoilCcontentisreached(AndrénandKätterer,2001). Comparedwiththosevalues,theestimatedsequestrationratefor fairwayandroughof0.3 MgCha−1year−1forourtwoSwedish siteswasfairlylow,althoughonlyslightlylowerthanthemedian Csequestration(0.42Mgha−1year−1)recordedinley-arable rota-tionsin15long-termﬁeldexperimentsunderNordicconditions (Kättereretal.,2013).Whiletheuncertaintyinourestimatesis high,sincewehadtorelyonseveralassumptionsduetolackof data,thehighersequestrationratesforsimilarsystemsreportedin thestudiescitedabovesuggestthatourestimatedsequestration rateof0.3MgCha−1year−1 isratherconservativeandits inclu-sioninthisLCAwouldnothaveovervaluedtheimportanceofsoil Csequestration.

5. Conclusions

EnergyuseandGHGemissionsperunitareawerehighestfor greens,followed by tees, fairways and roughs. However, when consideringtheentiregolfcourses,bothenergyuseandGHG emis-sionsweremainlyrelatedtofairwayandroughmaintenancedue tothelargerareatheyoccupied.Mowingwasthemost energy-consumingactivityand contributed 21 and27% of theprimary energyuseofthegolfcourses.Irrigationandmanufacturingof min-eralfertiliserandmachineryalsoresultedinconsiderableenergy use.Mowingand emissionsassociatedwithfertilisation (manu-factureof Nfertiliserand soilemissionsof N2Ooccurringafter

application)contributedmosttoGHGemissions.EmissionsofN2O

fromdecompositionofgrassclippingsareapotentialhotspotfor GHGemissionsfromturfmanagementthatneedsfurther inves-tigation,sincethehighspatialandtemporal variabilityofthese emissionsmakesitdifﬁculttoestimatetheiractualcontribution.

IncludingtheestimatedmeanannualsoilCsequestrationratefor fairway and roughin the assessment considerablyreduced the carbonfootprintforfairwayandturnedtheroughintoasinkfor GHG.Appropriatemeasuresforreducing energyuseandcarbon footprintfromlawnmanagementarethus:i)reducedmowing fre-quencywhenapplicable,ii)investmentinelectriﬁedmachinery, iii)loweringthemineralNfertiliserrate(especiallyonfairways) andiv)reducingtheamountandtransportofsandfordressing. Loweringthemineralfertiliserrateis of particularimportance, sinceGHGemissionsoriginatefromboththemanufacturingphase andfromNturnoverafterapplication.However,measuresmust beadaptedtotheprevailingconditionsatthespeciﬁcgolfcourse andtherequirementssetbygolfers.Thereisalsoaneedformore golfcoursesthatprioritiseandmarketalowenvironmental foot-printevenattheexpenseofe.g.currentaestheticpreferences.A lifecycle perspective asappliedin this studycan beusedas a toolfordecision-supportforgolfcoursesaimingatimprovingtheir environmentalperformance.

Conﬂictofinterest

Wedeclarethatnoconﬂictsofinterestofanykind(director indirect)exist.

Acknowledgements

Thisstudyformedpartofthemultidisciplinaryresearch pro-gramme“Lawnasecologicalandculturalphenomenon–Search forsustainablelawnsinSweden”,which wasfundedbyFormas (grantno.225-2012-1369),theSwedishResearchCouncilfor Envi-ronment,AgriculturalSciencesandSpatialPlanning.

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