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CONTEXTRainfedagricultureintheSahelianregionofsub-SaharanAfricaisplaguedbylowanderraticrainfallandstrongwinds,contributingtosoilerosionanddegradation.Itisestimatedthatapproximately50percentoffarmlandinWestAfricasuffersfromnutrientdepletionandpoorsoilfertility(Scherr1999).Small-scalefarmersinWestAfricahavetraditionallydealtwithpoorrainsanddegradedsoilsbyshiftingintoextensiveagriculture.YethighpopulationdensityandincreasingfrequencyofdroughtintheSaheloverthepast30yearshasresultedinshorterfallowperiodsandreducedtheavailabilityofarableland,therebymakingthesestrategiesunsustainableinthelonger-term(Warren,BatterburyandOsbahr2001).Inordertodealwithclimaticshiftsandfragilelands,sustainedyieldimprovementsintheSahelthereforerequiretechniquesthatbothincreasethelevelanddurationofwaterstoredwithinthesoil(viarainwaterharvesting,orRWH)andrepletesoilnutrients.Whilerainwatercanbeharvestedviain-siturainwaterconservation,thistechniqueispoorly

suitedtothesemi-aridareasofAfrica,wheresoilcovermaterialscompetewithlivestockfodder.Insuchcontexts,micro-catchments--smallstructuresconstructedwithinafieldtocollectsoilrunoffandincreasethenutrientcontentofthesoil–arethemostappropriateRWHtechnology.Themostcommonmicro-catchmentsusedintheSahelianregionofWestAfricaarezaï/tassa(soilpits),demi-lunes(half-moons)andbanquettes,someofwhichareindigenoustoWestAfrica.Variationsofthesemicro-catchmenttechniqueshavealsobeenadaptedinthesemi-aridzonesoutsideofWestAfrica,includingEthiopia,Kenya,TanzaniaandUganda.Decadesofresearchstationandon-farmtrialsintheSahelsuggestthatzaïanddemi-lunescansignificantlyreducesoilerosionanddegradationaswellastheriskofcropfailure(VohlandandBarry2009),aswellasincreasemilletyieldsincombinationwithmanureorinorganicfertilizers.YetadoptionofRWHtechniquesremainslow,especiallyinNiger:itisestimatedthatfewerthan10percentofsmall-scalefarmersusemicro-catchmentsonanypartoftheirland(WOCAT2009).Whyistheadoptionofthesetechnologiessolow?

AreRainwaterHarvestingTechniquesProfitableforSmall-ScaleFarmers?ResultsfromaPilotEvaluationinNiger

JennyC.Aker,TheFletcherSchool,TuftsUniversityMarch2018

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Therearenumerouspotentialreasons,suchashighconstructionandmaintenancecosts,limitedaccesstotechnicalinformationonthesetechniquesorthefactthatyieldimprovementsandprofitabilitymaynotbeobserveduntilthesecondyear.Overthepastdecade,numerousnon-governmentalorganizations(NGOs)havepromotedtheadoptionofRWHtechniquesbyprovidingtechnicaltrainingandconditionalcashorfoodtransferprograms.WhiletheseprogramshavebeensuccessfulinincreasingtheprevalenceofRWHtechniqueadoptioninparticularareas,theirabilitytoidentifytheunderlyingbarriershasbeenconstrainedbysmallsamplesizes,selectionbiasandmeasurementerror.

INTERVENTIONThispilotstudysoughttobetterunderstandthebarrierstoRWHadoption,aswellasmeasuretheimpactoftheiradoptiononfarmers’well-being.UsingarandomizedcontroltrialinNiger,andinpartnershipwiththeMinistryofEnvironmentandSahelGroup,farmerswereofferedoneofthreeinterventions:1)training:basictrainingforRWHtechniques,includingthenecessaryequipment,conductedbytheMinistry;2)UCT:trainingonRWHtechniquesandanunconditionalcashtransfer(cashadvance)worth$40,approximately50%ofthecostsassociatedwithconstructingdemi-lunesononehectareofland;and3)CCT:trainingonRWHtechniquesandaconditionalcashtransfer,wherebyfarmersreceiveacashpaymentforeverydemi-luneofacceptablequality,similartothevalueoftheUCT.ThislatterinterventionwassimilartoNGOCFWinterventionsinNiger.Thesamplesizeforthispilotwas30villagesintheDossoregionofNiger,targetingvillagesthatarethemostaffectedbysoildegradation.Withineachvillage,25farmerswereselected,foratotalof750farmers.Attheinitialmeetings,farmerswerenotinformedofthepotentialcashpayments,inordertoencourageparticipationofthoseinterestedintheRWHtechniquetechnology.Approximately¼ofthebeneficiarieswerewomen.

RESULTS

EffectonDemi-LuneAdoptionThepilotresultsshowedthatinterestinthesetechniqueswashigh:85percentofhouseholdsattendedthetrainings,regardlessoftheinterventiongroup,foratotalof637farmerstrained.Amongallofthefarmers,85%ofhouseholdsinthetrainingandUCTvillagesconstructeddemi-lunesontheirplots,whereashouseholdsinCCTvillageswere13percentagepointslesslikelytoconstructdemi-lunes.Thissuggeststhattraining(alone)canbeacost-effectivewaytogetfarmerstotrythetechnology.Yettheunconditionalcashtransferwashelpfulinencouragingfarmerstoconstructmoredemi-lunesontheirland:Whilehouseholdsinthetraining

villagesconstructedabout30demi-lunesperhectare,thoseintheUCTgroupconstructedabout47demi-lunesperhectare.AndthoseintheCCTvillagesconstructedfewerthanthoseinthetrainingorUCTgroup(Figure1).Theseresultswereconfirmedbyfarmers’self-reporteddataondemi-luneconstruction.Thissuggeststhatcashtransferswerenecessarytoovercomefarmers’creditconstraintsassociatedwithhiringlabor.Whileallofthesewerewellbelowthesuggestedtechnicalnormsof250demi-lunesperhectare,theevolutionofadoptionsuggeststhatfarmerswere“tryingout”thetechnologyovertimetoseehowitworked.Farmersinitiallyfollowedthespacingnormontheirplots.Inaddition,twoyearsafterthe

Figure1.Numberofanydemi-lunesconstructedbyinterventiongroup

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intervention,aqualitativestudysuggestedthatfarmerswereconstructingmoredemi-lunesonthoseplots,atapproximately20peryear.EffectsonInputUseandProductionAkeyquestionintheadoptionofanynewtechnologyiswhetherthattechnologyiswelfare-improvingforthosehouseholds.Usingdatafromahouseholdsurveyaftertheharvest,thepilotprogramsuggeststhatdemi-luneadoptionwasalsocorrelatedwithotherchangesininputuse,

agriculturalproductionandothermeasuresofwell-being.Overall,householdsintheUCTvillages–whohadconstructedmoredemi-lunesthantheirtrainingandCCTcounterparts–were18percentagepointslesslikelytouseinorganicfertilizerthanthoseintheCCTvillages,andmorelikelytouseinorganicfertilizer(manure),akeycomplimentaryinputfordemi-lunes(Figure2).Nevertheless,whileinorganicfertilizersmustbepurchased,manureisoftenreadilyavailablefromhouseholdlivestock.Overall,theseresultsseemtohavetranslatedintohigheragriculturalproductionforkeycropsplanted

indemi-lunes:householdsintheUCTvillagesproducedapproximately20kgmoremilletthanthoseinthetrainingandCCTvillages,respectively,withastatisticallysignificantdifferenceatthe5percentlevel(Figure3).Thisalsotranslatedintomodestimprovementsinwell-being:UCThouseholdshadhigherself-reportedmeasuresofwell-beingandmoredurableassets.Inparticular,householdsinUCTvillageswere12-14percentagepointsmorelikelytoownamotorcycleandcartthantheirtrainingandCCTcounterparts,suggestingthatthesehouseholdswereabletoinvestinagriculturaltechnologyandotherassets.

NEXTSTEPSResearchersarecurrentlyworkingwithNGOsandtheMinistrytoimplementafull-scaleresearchprogramin180villagesinNiger,buildinguponthepilotresults.Thefullstudywillalsomeasuretheimpactsofthetechnologyonsoilquality,akeyconstraintinSahelianWestAfrica.

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REFERENCESConcernWorldwide.2011.Evaluationdel’impact

desouvragesderécupérationdesterresdégradéessurlaproductionagricoledesménagesvulnérables.

Scherr,SaraJ.1999.“SoilDegradation:AThreatto

Developing-Country Food Security by2020?.” International FoodPolicyResearchInstitute:WashingtonDC

SIWI,IFPRI,IUCN,IWMI.2005.“LetitReign:TheNewWaterParadigmforGlobalFoodSecurity.”FinalReporttoCSD-13.StockholmInternationalWaterInstitute,Stockholm

Thiombiano,L.,2004.“Landdegradationassessmentandlandmanagement:IndigenousknowledgesystemsasanheritageforaWayforward.”TrainingcourseUNU-FAOfrom14to19June.CD-ROM.

Vohland,KatrinandBoubacarBarry.2009.“AReviewofInSituRainwaterHarvesting(RWH)PracticesModifyingLandscapeFunctionsinAfricanDrylands,”Agriculture,EcosystemsandEnvironment.131:119-127.

Warren,Andrew,SimonBatterbury,andHennyOsbahr.2001.“SustainabilityandSahelianSoils:EvidencefromNiger.”TheGeographicalJournal.167:4(2001):324-341.

WOCAT.2009.WOCATdatabaseonSLMtechnologiesandSLMapproaches.www.wocat.net,accessedon15September2009.