J.Viet.Env.2018,10(1):49-55DOI:10.13141/jve.vol10.no1.pp49-55

49

*CorrespondingauthorE-mail:ntttruc@ctu.edu.vn

http://dx.doi.org/10.13141/JVE/ISSN:2193-6471

R E S E A R C H A R T I C L E

Quantification of direct and indirect greenhouse gas emissions from rice field cultivation with different rice straw management practices – A study in the autumn - winter season in An Giang Province, Vietnam

Phát thải khí nhà kính trực tiếp và gián tiếp từ sản xuất lúa theo các biện pháp quản lý rơm rạ khác nhau – Một nghiên cứu ở vụ Thu Đông ở tỉnh An Giang, Việt Nam

NGO Th i T h anh T r u c 1 * ; HO Vu Khanh 2 ; T RAN S y Nam3 ; DUONG Van Ch i n 4 ; NGUYEN Van Cong 3 ; NGUYEN Van Hung 5 1DepartmentEnvironmentalandResourceEconomics,CollegeofEconomics,CanThoUniversity,CanTho,Vietnam;2FacultyofEnvironmentandNaturalResources,KienGiangUniversity,KienGiangProvince,Vietnam;3DepartmentofEnvironmentalScience,CollegeofEnvironmentandNaturalResources,CanThoUniversity,CanTho,Vietnam;4LocTroiGroup,AnGiangProvince,Vietnam;5InternationalRiceResearchInstitute,LosBaños,Philippines

Thisstudyresultedinacomparativeanalysisofgreenhousegasemissions(GHGE)forriceproductionwithdifferentin-fieldricestrawmanagementpracticesbasedonanexperimentconductedinAnGiangProvinceofVietnam,duringtheautumn-winterseasonof2016.DirectfieldGHGEwasanalyzedbasedonin-situmeasurementandthetotaldirectandindirectGHGEwereestimatedbyapplyingthelifecycleassessmentusingEcoinvent3databasewhichisincorpo-ratedinSIMAPROsoftware.Theexperimentwasconductedbasedonacompletelyrandomdesignwiththreetreat-mentsandthreereplications.Thethreetreatmentsare[T1]IncorporationofstrawandstubblestreatedwithTricho-derma;[T2]Incorporationofstubblesandremovalofstraw;and[T3]In-fieldburningstraw.Closedchamberprotocolandgaschromatography(SRI8610C)wasusedtomeasureandanalyseCH4andN2O.CH4emissionratewasnotsignif-icantlydifferent(p>0.05)amongthethreetreatmentsduringsamplingdatesexceptonthedays17and24aftersowing(DAS).N2Oemissionratewasnotsignificantlydifferent(p>0.05)either.However,therewerehighvariationsofN2Oemissionafterthedatesofureaapplied.DirectfieldemissionsofCH4,N2OandCO2equivalent(CO2eq)arenotsignifi-cantlydifferentamongthethreetreatments,buttheamountofCO2eqperkgstrawinT1ofincorporatingricestrawtreatedwithTrichodermaissignificantlyhigherthaninT3ofin-fieldburningstraw.LCAbasedanalysisresultedintotalGHGEintherangeof1.93-2.46kgCO2-eqkg

-1paddyproducedconsistingof53-66%fromdirectsoilemissions.Incor-porationofstrawtreatedwithTrichodermadidnotindicatetheimprovementofpaddyyield.However,theorganicmatter,N-NH4

+,andN-NO3-ofthistreatmentwashigherthanthoseoftheotherresearchedtreatments.Thisresearch

wasjustconductedinonecropseason,however,theresultshaveinitialimplicationsfortheothercropseasons.

NghiêncứunàyphântíchphátthảikhínhàkínhtừsảnxuấtlúatheocácbiệnphápquảnlýrơmrạkhácnhaudựavàothínghiệmđượcthựchiệnởvụThuĐôngnăm2016tạitỉnhAnGiang,ViệtNam.LượngphátthảikhínhàkínhtừđấtđãđượcphântíchdựavàokếtquảđođạttạiruộngvàtổnglượngphátthảikhínhàkínhtrựctiếpvàgiántiếpđượcướctínhbằngphươngphápvòngđờisửdụngcơsởdữliệuEcoinvent3gắnkếtvớiphầnmềmSIMAPRO.Thínghiệmđượcbốtríhoàntoànngẫunhiêngồm3nghiệmthứcvà3 lầnlặplại.Cácnghiệmthứcgồm[T1]vùirơmvàrạvớiTrichoderma,[T2]lấyrơmrakhỏiruộngvàvùirạvà[T3]đốtrơm.Kỹthuậtbuồngkín(closedchamberprotocol)vàmáysắckýkhí(SRI8610C)đượcsửdụngđểđođạtvàphântíchkhíCH4vàN2O.TốcđộphátthảikhíCH4khôngkhácbiệtgiữabanghiệmthức,ngoạitrừkếtquảởlầnlấymẫu17và24ngàysausạ.TốcđộphátthảiN2Ocũngkhôngcósựkhácbiệtgiữacácnghiệmthức.Tuynhiên,tốcđộphátthảibiếnđộngrấtlớnsaucácngàybónphânđạm.LượngphátthảitrựctiếptừruộngcủaCH4,N2OvàCO2tươngđương(CO2-eq)khôngcósựkhácbiệtgiữabanghiệmthức,nhưnglượngCO2-eq/kgrơmởnghiệmthứcvùirơmvàrạvớiTrichoderma(T1)caohơnnghiệmthứcđốtrơm(T3).KếtquảphântíchLCAchothấylượngphátthảikhínhàkínhdaođộngtrongkhoảng1,93–2,46kgCO2-eq/kglúavới53–66%lượngphátthảitrựctiếptừtrongđất.VùirơmrạvớiTrichodermachưacảithiệnđượcnăngsuấtlúa.Tuynhiên,phầntrămchấthữucơvàhàmlượngđạmhữudụngtrongđấtcủanghiệmthứcnàycaohơnsovớihainghiệmthứccònlạicủathínghiệm.Nghiêncứunàychỉmớiđượcthựchiệnmộtvụ,nhưngđãmanglạinhiềukếtquảcóthểứngdụngchocácvụsau.

Keywords: GHGE,methane,nitrousoxide,strawmanagementpractices

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1. Introduction Lowlandricecultivationisoneoftheimportantsourcesofgreenhousegasemissionsinagriculture(Bhattacharyyaetal.,2012).AccordingtoVSC(2014),Vietnamemittedap-proximately46thousandtonsofCO2eqfromriceproduc-tion,whichaccountedfor50.5%oftotalGHGEfromagri-culturalactivities.Causesofgreenhousegasemissions inriceproductionareirrigatedricecultivation,over-fertiliza-tion, unsustainable straw and water management, andhigh density of sowing (Wassmann, 2000; Trinh et al.,2013;Tinetal.,2015).MekongDeltaproducesabout24–26milliontonsofricestrawannually(GSO,2016;Araietal.,2015).However,themostcommonpracticeofricestrawmanagementisopenburning(54–98%)andincorporatingfreshricestraw(7-26%)(Nametal.,2014;Trucetal.,2012).Only2–13%ofricestrawisusedtoproducestrawmushroom(Volvariellavovaraceae)andfeedforcattle.Burningricestrawispop-ular due to intensification, limit of straw utilization, andlackofregulationonburningstraw(Trucetal.,2012and2013).Openburningricestrawcausesairpollutionandlossofnu-trients while incorporating fresh straw and stubble re-leasesgreenhousegasemissions,aswellasorganicpoisontotheyoungpaddy(Gaddeetal.,2009;Gaoetal.,2003;NguyenQuocKhangandNgoNgocHung,2014).Inordertorecommendthebetterpracticeofricestrawmanage-ment, an experiment on in-situ rice straw practice hasbeen conducted to estimate direct and indirect green-housegasemissions.ThefirsttreatmentwasincorporatingricestrawandstubblewithTrichoderma.Trichodermaactsasanactivatortospeedupthedecompositionprocessin15–25days,reducingorganicpoisonwhenincorporatedwithfreshstraworstubbletothepaddyfield;andsupple-mentingorganicnutrientsaswell(Sonetal.,2008;TuyenandTan,2001).Thetwoothertreatmentsareincorporat-ingfreshstubbledirectlytothefield,andin-fieldburningofricestrawwhichisthemostpracticedricestrawman-agement in theMekong Delta (Nam et al., 2014). Afterquantifyingin-situgreenhousegasemission,thisstudyalsocalculatedthetotalgreenhousegasemissionbylifecycleassessment.

2. Materials and methodologies 2.1 Experiment set up and materials

Materials:RicecultivationwasconductedduringAutumn-Winterseasonsof2016(AugusttoDecember)atDinhThanhAgricultural Research Center in AnGiang province of Vi-etnam(10018’45.19”N;105018’57.87”E).TheexperimentaldesignappliedwastheCompleteRandomizedDesign(CRD)with3treatmentsnamely[T1] Incorporationofstrawandstubbles treatedwithTrichoderma; [T2] Incorporationofstubbles and removal of straw; and [T3] In-field burningstraw.Theexperimentalplotof25m2andthreereplications

weredone.ThequantityofstrawandstubbleaddedintheexperimentislistedinTable1.Table 1: Quantity of straw and stubbles added in the experi-

ment

Treatment Strawmanagement

Quantity(kgha-1)Straw Stubble

T1 Incorporated 2,697±140a 3,852±201aT2 Removed 2,563±7.1a 3,660±10.1aT3 Burning 2,850±86.6a 4,071±124a

Note:Meansfollowedbythesameletterarenotsignificantlydifferentamongsamplingdaysat0.05levelasdeterminedbyDuncanAgronomicandchemical inputs for the three treatmentsaredescribed inTable2.Riceseedsweresownbydrumseeder.Fertilizerwasappliedat10,20,and50daysaftersowing(DAS)(panicleinitiationstage).Table 2. Agronomic and chemical inputs in the experiment

Unit:kgha-1Inputs Tradename QuantityVariety LocTroi1 100Trichoderma TRICO-DHCT-LUAVON 1*N Urea(46%N);DAP

(18%N-46%P2O5)90

P2O5 DAP(18%N-46%P2O5) 45

K2O KCl(46%K2O) 45

Note:onlyTrichodermawasaddedinT12.2 Measurement and analysis

Gasmeasurement: Gasmeasurement and analysis wereadoptedfromtheguidelineofMinamikawaetal.,(2015).Gas samples were collected based on closed chambermethodat0,10,20,and30minutes,thenstoredin30mlvacuumvials.

Figure 1. Chamber to collect a gas sample

The chamber contains two main parts namely, the gaschamberwithavolumeof120Landheight70cmheight(V1),andthebasewithadiameterof50cmandheightof30cm(V2)(Figure1).SamplingsofGHGEwereconductedafter10DAS.Thegassampleswerecollectedat9ameveryweekuntil45DASandeverytendaysuntil95DAS.CH4andN2Oconcentra-tionwereanalysedusinggaschromatography(ModelSRI8610C,HayeSept-N)withFIDandECDdetectors.

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Directfield-emissionformula:CH4andN2Orateswereesti-matedbythefollowingformula(Parkinetal.,2003):

)*08206.0(*10*24*60*TA

MVx

dtdC

F =

whereF:CH4orN2Oflux(mg.m-2.day-1);T:temperatureinthe chamber (°K); V: volume of chamber; M: molecularweight of CH4 or N2O; A: surface area of chamber (m2);

dtdC :rateofgasconcentrationinthechamber(ppm.h-1);

andV:volumeofchamber(V=V1+V2).Again,V1istheup-perpartofthechamber,V2isthelowerpartofthecham-ber(V2=A.h);whilehistheheightofwaterlevelfromthegroundsurfaceinsidethechamberandadjustedwhenthewaterlevelishigherthanthegroundsurface.Theaverageemissionrateiscalculatedby:

n

FF

n

iå=

-1

whereFi:CH4orN2Ofluxofsamplingdate(mg.m-2.day-1),andn:numberofgassampling(n=11).ThetotalquantityofCH4orN2Oemissionperseason(autumn-winterseason)

isequalto-

F multiplybythenumberofdaysperseason(100days).Indirectfield-emissionformula:GHGEconversionfactorsofallrelatedmaterialswerebasedonthedatabaseofEcoin-vent3incorporatedinSIMAPROsoftware.Dieselconsump-tion for mechanized operations and seed rate were as-sumed150litresand100kgperhabasedonthenormalpracticesobservedintheexperimentedareas.Indirectly calculated emissions of the fuel consumptionsandagronomicinputsusedtheconversionfactorsshowninTable3.Forstrawburning,weusedtheemissionfactorsofCH4andN2OreportedinRomasantaetal.(2017).Thisindicatedthatburning1tonofstraw(drymatter)causedtheemissionsof4.5and0.069gramofCH4andN2O,respectively.Table 3. GHGE conversion factors of fuel, agronomic inputs,

and products

Parameters GHGE SourceUnit Value

Seeds kgCO2-eqkg-1 1.12 a

Dieselconsumption kgCO2-eqMJ-1 0.08 aNitrogen(N) kgCO2-eqkg

-1 5.68 aP2O5 kgCO2-eqkg

-1 1.09 aK2O kgCO2-eqkg

-1 0.52 aCH4 kgCO2-eqkg

-1 30.5 bN2O kgCO2-eqkg

-1 265 b(Source:a=Ecoinvent,2016andb=IPCC,2013)

SoilandwatermeasurementsSoilsampleswerecollectedbeforeincorporatingstrawandstubbles, 30, 60 and 90 DAS for each plot. Soil samplesweretakenat0–20cmfromthesurfacetomeasureN-NH4

+/N-NO3-andorganiccontent.

Redoxwasmeasured inall nineplotswith three replica-tionsbySWC-201RPatthesamedateandtimeofgassam-plecollection(at9amonthegassamplingdate).Water management followed the alternate wetting anddrying (AWD) technology. However, it was not followedstrictlyduetotherainyseason.Thewater levelwasrec-ordedat8ameverydayattheexperimentplot.Cropmeasurement:Actualpaddyyieldwasestimatedbyharvestingyieldof5m2plotsinallninetreatmentplotsandestimateddryyield(at14%moisturecontent).2.3. Statistical analysis

MeansamongtreatmentsofCH4,N2OandCO2-eqandrelatedparametersweretestedbyanalysisofvariancewithDuncantestof95%confidence.Besides,correlationanalysisofwa-terlevelandredoxwasalsousedbyPearsontests.

3. Results and discussions 3.1 Water level and redox potential

Waterlevelsinthepaddyfieldvariedfrom–13cmto5cmduringexperimental95-day-period (Fig.1a).Waterman-agement in this experiment tried to follow the alternatewettinganddrying(AWD)technologyevenitwasinrainyseason.AccordingtoBharatietal.(2001),thewaterlevelinthepaddyfieldmayaffecttheoxidationprocessinthesoil, and thusmay affect the emissions of CH4 andN2O.However, there are no significant correlations betweenwaterlevelandredoxamongthreetreatments.In the first 45DAS, the redox potentialwas low rangingfrom -120 to -160mV in all treatments (period of 10-46daysinFig.2b).Itisindicatedthatthereductionprocessinthesoilwasthemainprocesswhichhappenedduringthisperiod.The reason for this trendwascausedby the fastdegradationofthestrawbiomassinthefirst45DAS.Thentheredoxincreasedgraduallyuntil95DASduetothelowwaterlevelandslowstrawdegradationattheendoftheseason.

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Figure 2. Water level (a) and redox potential (b)

3.2 Emissions of CH4 and N2O

3.2.1DirectlyemissionrateofCH4The average CH4 emission rates of T1, T2 and T3 treat-mentsfluctuatedfrom139.7–222.6mg.m-2.day-1(Fig.3).TheemissionrateofCH4inT1wasnotsignificantlydiffer-ent from T2 and T3 treatments (p>0.05) inmost of thesamplingdates,except in17and24DAS.Thestrongde-compositionprocessofT1duringthisperiodmaybethereason for the high CH4 emission in comparisonwith T2andT3.AccordingtoDuetal(2014),Trichodermacande-composeupto40%ofthestrawwithin20days.AnotherreportfromHoi(2008)concludedthatthedecompositionrateofricestrawwashighestinthefirst15days,thenthedecompositionrateslowsdowncausingthestrawweighttodecreaseslowly.TherearehighvariationsinCH4emissionratesamongpre-vious researches.Forexample,NeueandSass (1998) re-ported that theaverageCH4emission rate ina rice fieldranged from 240 to 520 mg.m-2 days-1. Meanwhile, thestudy conducted by Bhattacharyya et al. (2012) showedthat CH4 emission rates ranged from 45.6 - 137 mg.m-

2.days-1. The lowest emission rate was 85 DAS at 5.87mg.m-2.days-1inwhichwaterlevelwas-1cmandredoxwas-112mVinalltreatments(Fig3).

Figure 3. Direct emission rate of CH4

Note:Means followedby the same letter arenot significantly differentamongsamplingdaysat0.05levelasdeterminedbyDuncan3.2.2.DirectlyemissionrateofN2OTheemissionofN2Ointhreetreatmentsvariedfrom0–6.57 mg.m-2.day-1 and there were no N2O emissions inmostofthesamplingdates(Fig.4).Thedatashowedthatjust after applying chemical fertilizers, theN2O emissionwasincreasedlater.Whenfertilizerswereappliedon8,20,and55DAS,theN2Oemissionson10,24,and65DASweredramaticallyincreased(Fig.4).Snyderetal.(2007)alsore-ported that N2O emissions are closely related to theamount of nitrogen applied in the field. However, therewasnosignificantdifferenceamongthethreetreatmentsin terms of N2O emission (p>0.05). It seemed that N2Oemission is more closely related to fertilizer applicationthanstrawmanagementpractices.The knowledge and research on N2O emission from thepaddyfieldwerequite limitedcomparedtoCH4(Jiangetal.,2003).However,accordingtoLouetal.,(2007),incor-poratingricestrawincreasesN2Oemission,incomparisonwith removing the straw from the field. TheemissionofN2Oisincreasedwhenthesoilisfertilizedbyorganicmat-ter,duetotheincreasednitratereductionandnitrificationof NH4

+ in partly or full aerobic condition (Khuong andHung,2014).

Figure 4. Direct emission rate of N2O

3.2.3TotaldirectlyemissionofCH4,N2OandCO2eqa.TotalCH4andN2Oofdirectemissions

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Fig.5 illustratesthattheaveragetotalemissionofCH4 is179.1 ± 24.0 kg.ha-1.season-1 (T1, T2 and T3 are 222.6,174.9,and139.7kg.ha-1.season-1,approximately).Thesta-tisticalanalysisshowedthattherewasnosignificantdiffer-ence in CH4 emissions among the three treatments(p>0.05).This value ishigher than thevalue reportedbyLinquistetal.(2012)at100kgCH4.ha

−1.season-1.

Figure 5. Total emission of CH4

Note:Meansfollowedbythesameletterarenotsignificantlydifferentat0.05levelasdeterminedbyDuncanSimilarly,therewasnosignificantdifferenceinN2Oemis-sions among three treatments, and it highly fluctuatedfrom0.21–1.16kg.ha-1.season-1(Fig.6).TheN2Oemissionalsovariedinalltreatments(Fig.6).Studyingpaddyfields,Pittelkowetal.(2013)statedthatthetotalemissionswere0.2to0.4kgN2O.ha

-1,whichwaslowerthantheN2Oemis-

sionfoundinthisstudy.TheresultofN2Oneedstobecon-firmedbyrepeatingthisexperiment inbothdryandwetseasons.

Figure 6. Total emission of N2O

Note:Meansfollowedbythesameletterarenotsignificantlydifferentat0.05levelasdeterminedbyDuncanb.TotaldirectemissionsofCO2eqTheemissionofCO2eqwas4,330–7,097kgCO2eq.ha

-1andit was not significantly different among the three treat-ments(Table4).However,theemissionofCO2eqperkgofricestrawincorporatedtothericefieldwithTrichodermainT1 (2.63±0.24kgCO2eq.ha

-1.kg ricestraw-1)wassignifi-cantly higher than that of T3 treatment (1.52 ± 0.35 kgCO2eq.ha

-1.kg rice straw-1). The result of this study is inagreementwiththatreportedin2006IPCCguidelinesandotherstudiesforthesimilarstudiesofstrawincorporationwithTrichodermaorcompost(Truc,2011;Wassmannetal,2000).

Table 4. CO2 equivalent emission

TreatmentYields(kg.ha-1)

Ricestraw(kg.ha-1)

CO2eq(kgCO2.ha

-1.season-1)CO2eq

(kgCO2eq.kgpaddy-1.season-1)

CO2eq

(kgCO2.kgstraw-1.season-1)

T1 4,360±112a 2,697±140a 7,097±639a 1.62±0.15a 2.63±0.24aT2 4,400±97.0a 2,563±7.10a 5,390±743a 1.22±0.17a 2,10±0.29abT3 4,250±85.0a 2,850±86.6a 4,330±991a 1,02±0.23a 1.52±0.35bAverage 4,337±98.0 2,703±77.9 5,605±806 1.29±0.18 2.08±0.19Note:Mean±StandardError;Meansfollowedbythesameletterarenotsignificantlydifferentat0.05levelasdeterminedbyDuncan3.3 Yields and nutrients in the soil

RiceyieldsofT1,T2andT3treatmentswerefrom4.25to4.40 ton.ha-1 and therewasno significantdifferencebe-tweenthreetreatments(p>0,05)(Table4).Itneedsatleasttwo or even longer time to see the difference in yieldamong different rice strawmanagement (Surekha et al.2003;Sonetal,2008;KhuongandHung,2014;Duetal,2014).Besides,theyieldisbetterimprovedinSpring-Win-terSeasonratherthaninAutumnWinterseasonasinthisexperiment.Theresults inFig.7andFig.8showthator-ganiccarboncontentandnitrogenavailable (N-NH4

+andN-NO3

-)inthesoilintreatmentT1wassignificantlyhigherthaninT2andT3attheendoftheseason.Miletal.(2012)reportedthatstrawincorporationinsoilreturns40%ofN,30%ofPand80%ofK(whichisabsorbedbyrice);strawincorporationalsoincreasesorganicmatterinsoilaswell.Ontheotherhandstrawburningresultsinlosing70-80%ofCandNinstraw(Hilletal.,1999).Theimprovementof

carbonandnitrogencontentsavailableinsoilwasoneoftheevidencethatsoilandpaddyyieldcanbeimprovedinthelongterm.

Figure 7. Organic matter in the soil (%)

Note:Mean±StandardError;Meansfollowedbythesameletterarenotsignificantlydifferentat0.05levelasdeterminedbyDuncan

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Figure 8. N-NH4

+ and N-NO3

- concentration in soil

Note:Mean±StandardError;Meansfollowedbythesameletterarenotsignificantlydifferentat0.05levelasdeterminedbyDuncan3.4 Total greenhouse gas emissions (GHGE)

Figure9showsGHGE(kgCO2eq.ha

-1)ofthecomponentsconstituting to the total emissions for three treatments(i.e.T1,T2,andT3).TotalGHGEwasintherangeof8,187-10,739kgCO2eqha

-1,equalingto1.93-2.46kgCO2-eqkg-1

paddyproduced(moisturecontentofpaddywasat14%inwet basis). The results showed that incorporation of allstraw(T1)hadthehighestGHGEat10,739kgCO2-eqha

−1

season-1.ContributiontotheoverallGHGE,thehighestwasfrom direct field-emission during rice cultivation ranging53-66% of the total GHGE.Mechanized operations con-sumingfuelalsocontributedarangeof26-34%,whiletheagronomic inputscontributeabout7%of the totalemis-sions.

Figure 9. Total greenhouse gas emissions from three treat-

ments

4. Conclusions CH4andN2Oemissionrateswerenotsignificantlydifferentamong the treatments; however, therewere high varia-tionsofN2Oemissionafterthedateswhenureawasap-plied.DirectfieldemissionsofCH4,N2OandCO2equivalent(CO2eq)arenotsignificantlydifferentamongthethreetreat-ments,buttheamountofCO2eqperkgstrawinT1ofincorpo-rating rice straw treatedTrichoderma is significantly higherthan in T3of in-fieldburning straw. LCAbasedanalysis re-sulted intotalGHGE in the rangeof1.93-2.46kgCO2-eqkg-1paddyproducedconsistingof53-66%fromdirectsoil

emissions. Incorporation of straw treated with Tricho-derma didnot indicate the improvementofpaddy yield.However,theorganicmatterandN-NH4

+andN-NO3-ofthis

treatmentwerehigherthanthosefromotherresearches.Thisresearchwasjustconductedinonecropseason,how-ever,theresultshaveinitialimplicationsfortheothercropseasons.Toverifytheseresults,werecommendtoconductfurtherexperimentswithreplicationsofcropseasonsandextendingtootherseasonsandcroppingsystems.Acknowledgement.Thisresearchwasconductedincollab-orationwiththeInternationalRiceResearchInstitute(IRRI)throughtheBMZ-IRRIproject"Scalablestrawmanagementoptionsforsustainabilityandlowenvironmentalfootprintin rice-based production systems” (contract No.81194994).WewouldliketothankDr.NguyenThanhNghi(NLU)forsupportingthisstudy.Thankstoallthestudentsin CTU, especially Thi Quoc Phong, VuQuoc Tin andHoMinhNhut,andthestaffofDTARCforsupportingthedatacollectioninthisstudy.

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0

2,000

4,000

6,000

8,000

10,000

12,000

T1 T2 T3

kg C

O2-

eq h

a-1se

ason

-1

Straw burning

Direct field-emissionK2O

P2O5

Nitrogen

Seed

Fuel-mechanizedoperations

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