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  • BASE Biotechnol. Agron. Soc. Environ.201418(1),142-154 Focus on:

    SoilscienceandagriculturaldevelopmentinRwanda:stateoftheart.AreviewPascalN.Rushemuka(1,2),LaurentBock(2),JeremiasGasperMowo(3)(1)RwandaAgriculturalBoard(RAB).Box617.Butare(Rwanda).E-mail:Rushem2005@yahoo.fr(2)Univ.Liege-GemblouxAgro-BioTech.DepartmentSciencesandTechnologiesoftheEnvironment.Soil-WaterSystems.AvenueMarchalJuin,27.B-5030Gembloux(Belgium).(3)WorldAgroforestryCentre.Box30677.Nairobi(Kenya).

    ReceivedonApril19,2012;acceptedonSeptember18,2013.

    PooragriculturalproductivityremainsacrucialprobleminRwandainspiteofnumeroustechnologicalinterventions,includingaspectsof soilmanagement.Theobjectiveof this studywas todraw lessons from thepastwith theview tobetterorientfuture interventions insoil fertilitymanagement.Theliteraturereviewanditerativefieldobservationswere thesourcesofinformation.Findingsfromthisstudyshowthatsubstantialprogresshasbeenmadeintheidentificationofdifferentsoiltypesandtheirspatialdistribution.Factorsrelatedto lowlevelofproductivityhavebeenidentifiedandsustainablesoil fertilitymanagementoptionshavebeendevelopedatplotlevel.However, thewidespreadadoptionofthesetechnologieshasbeenproblematic.Themainreasonisthefailuretotailorsoilfertilitymanagementtechnologiestospecificsoiltypes.Thestudyhasdemonstrated that thesoilmapofRwanda(CPRforCarte Pdologique du Rwanda)1:50,000offersaremarkablepotentialtoconstituteatooltosolvethisproblem.Inpracticehowever,theCPRremainsunderutilized,mainlybecauseofitsinaccessibilitytoitspotentialusers(e.g.policymakers,soilfertilityexperts,agronomistsandextensionists).Foritseffectiveuse,thefollowingisrecommended:Rwandansoilscientistsneedtoincreasepolicymakersawarenessabouttheusefulnessofthissoilmap;agriculturalresearchneedstoadaptfromtheconventionalmodeltoatrulyparticipatoryandintegratedapproach;theCPRlegendshouldbeelucidatedbyprovidinginformationonthelandunitsinwhichsoilsoccurandbybridgingSoilTaxonomywiththefarmerssoilnomenclature;regionalsoilreferencesystemsshouldbeestablishedthatallowlinkingsoiltypeswiththefertilitystatusofarablelandandcropyields.ThisimpliestheneedfortrainingofRwandansoilscientistsinbothSoilTaxonomy(thelanguageoftheCPR)andthefarmerssoilnomenclaturesothattheycanserveasinterpreterforscientistsfromotherdisciplinesandfarmers.RwandansoilscientistsshouldbetrainedintheuseofGeographicInformationSystem(GIS)softwaretoenablethemtoexploitthedigitizedversion/softcopyoftheCPRandtobecomefamiliarwiththeRwandanbiophysicalenvironment.Keywords.Soilsciences,soilmap,agriculturalresearch,informationexchange,ruraldevelopment,Rwanda.

    Science du sol et dveloppement agricole au Rwanda : tat de la question (synthse bibliographique). AuRwanda,malgrplusieurs interventions techniques, encecompris lesaspectsde lagestiondes sols, la faibleproductivitagricoleresteunproblmecrucial.Lobjectifdecettetudetaitdetirerlesleonsdupassenvuedemieuxorienterlesinterventionsfuturesengestiondelafertilitdessols.Larevuedelalittratureetlesobservationsitrativessurterrainontservidesourcedinformation.Lesrsultatsdecettetudemontrentquunprogrssubstantielatralisdanslidentificationdesdiffrentstypesdesolsetdeleurrpartitionspatiale.Lesfacteursresponsablesdufaibleniveaudeproductivitdesterresonttidentifisetlesoptionsdegestiondurableonttdveloppeslchelledelaparcelle.Cependant,leuradoptiongrandechelleestresteproblmatique.Laraisonprincipaleapparaittrelincapacitdadapterlestechnologiesdegestiondelafertilitauxdiffrents typesdes sols.Cette tudemontredoncque laCartePdologiqueduRwanda (CPR) -1:50000 constitueunoutilpossiblepourrsoudreceproblme.Enpratiquecependant,laCPRrestesous-utilise,principalementcausedesoninaccessibilitsesutilisateurspotentiels(planificateurs,expertsengestiondelafertilit,agronomesetvulgarisateurs).Poursonutilisationeffective,lesrecommandationssuivantesonttformules:lespdologuesduRwandadevraientsensibiliserlesplanificateursproposdelutilitdecettecartedessols;larechercheetvulgarisationagricolesdevraientpasserdelapprocheconventionnelleuneapprocherellementparticipativeetintgre;lalgendedelaCPRdevraittreexpliciteenyincluantlesunitspaysagiques/morphologiquesetentablissantdespontsdecommunicationentrelalgendetaxonomiquedelaCPRetlesnomsvernaculairesdessols;dessystmesrgionauxderfrencesurlessolsdevraienttretablis,quipermettentdemettreenrelationlestypesdesols,ltatdefertilitdesterrescultivesetlesrendementsobtenus.Ceciimpliqueunbesoin

  • SoilscienceandagriculturedevelopmentinRwanda 143

    1. INTRODUCTION

    Soil is studied from both fundamental and appliedpointsofview.Theknowledgeacquiredbybasicsoilscience is published in scientific journals and books.However, theway the information generated by thisscientific sub-discipline is used to formulate soundpolicies and translated into soil-specific and user-tailoredtechnologiesinappliedsoilscienceiscomplexandcontroversial.

    While Hartemink (2006) maintained that soilscience has contributed to the increase in worldagricultural food production over the last 50years,manyotherauthors(Papadakis,1975;Leeuwisetal.,2004; Ruellan, pers. com.) asserted that the increasein agricultural food production in the industrializedworld was made possible less by progress in soilscienceandacademicresearchthanbytheagronomicsciences, which developed responsive fertilizervarieties, pesticides and intensive use of fertilizers,agricultural engineering, value chain developmentandmarkets.Theproblem is that thiscapital-ledandnonsoil-specificintensificationoffoodproductionhasoccurredat theexpenseof thecapacityof thesoil tosustainablyproducefoodandsupportlife(Rainaetal.,2006;Ruellan,pers.com.;Herren,2011).

    Despite the above concerns, in those developingcountrieswherefoodproductionhasstagnatedoverthelast50years,thereisagreattemptationtoimitatethedevelopedworld.Forinstance,intheAfricanFertilizerSummit, the conclusions of which were endorsedby theAfrican Heads of State atAbuja, Nigeria, in2006,itwasarguedthatforagreenrevolutiontotakeplace inAfrica, fertilizerusemustbe increased fromthe then mean of 8kg.ha-1 to ~ 50kg.ha-1 by 2015.Accordingly, African governments were encouragedto takeconducivemeasures to increase fertilizeruse.Following these recommendations, several Africancountries have used subsidies in efforts to increasefarm-levelfertilizerapplications(Marenyaetal.,2012).It is also in this context that Rwanda has promoteda policy of agricultural modernization and cropintensificationwithlandconsolidation,mechanization,mono-cropping,highyieldingcropvarieties,intensiveuse of fertilizers and irrigation (MINECOFIN, 2000;MINAGRI,2002;MINECOFIN,2007).

    Agro-ecologists,whilesharingthesameconcernsaboutregardinglowagro-systemproductivity,wouldprefer not to see developing countries repeatingthe past errors of the developed world.Within thiscontext, they consider agro-ecological solutionsor Ecological Agriculture (EA) (minimum useof fertilizers and investment in agroforestry) tobe superior to conventional agriculture based onchemicals or Industrial Agriculture (IA). Theythus propose measures to governments to lead thedevelopmentandadoptionofsuchapproaches(Altieri,2002;deSchutter,2010;Herren,2011;Marenyaetal.,2012). Soil scientists, for their part, maintain thatagro-ecological solutions are unable to contributesignificantly to food securityandpovertyalleviationwithin the context of acid and inherently poor soils,such as those found in many parts of sub-SaharanAfrica (Drechsel et al., 1996; Rutunga et al., 2006;Breman,2011;Keatingetal.,2011).

    Several questions arise: is the debate about IAversus EA new? Has any progress been achieved?Whatpositionshouldgovernmentstake?Shouldtheywait forscientists toreachacompromise,or isevenanycompromisepossible?

    The objective of this study is to analyze howsoil science has evolved in Rwanda, what has beenachieved, how these achievements have contributedtoagriculturaldevelopment,whattheconstraintshavebeen,andwhatmightconstitutethewayforward.

    2. METHODOLOGICAL APPROACH

    A literature review, including unpublished reports,maps and journal articles, was the main source ofinformation for this study. A historical perspectiveapproachwasusedtoanalyzethecontributionofsoilscience to agricultural development inRwanda.Thehistorical time-frame covers a period of ~80years(1930-2010).Threeyears(2010-2013)ofiterativefieldactivityobservationswereundertaken to support theliterature reviewwith concrete and recent examples.Figure 1 presents the location of Rwanda withinAfrica,theAgro-EcologicalZones(AEZs)ofRwanda(Verdoodtetal.,2003a)andthemainsitescitedinthetext.

    pouruneformationdespdologuesduRwandalamaitrisedelaSoil Taxonomy (langagedelaCPR)etdelanomenclaturevernaculairedessolsafinquilsserventdinterprtespourlesnon-pdologuesetlespaysans.Aummemoment,ilsdevraientaussi recevoirplusdeformationsur lutilisationdes logicielsdeSystmesdInformationGographiques(SIG)afindtrecapablesdexploiterlaversiondigitalise/lectroniquedelaCPRetdevenirfamiliersaveclemilieubiophysiquerwandais.Mots-cls.Sciencesdusol,cartedesols,rechercheagricole,changedinformation,dveloppementrural,Rwanda.

  • 144 Biotechnol. Agron. Soc. Environ. 201418(1),142-154 RushemukaP.N.,BockL.&MowoJ.G.

    3. SOIL SCIENCE COMPONENTS AND ACHIEVEMENTS IN RWANDA

    Soil science, as applied in agricultural research anddevelopmentinRwanda,istraditionallysubdividedintothreemaincomponents:soilsurvey,soilconservation,andsoilfertilitymanagement.

    3.1. Soil survey

    ThefirstsoilsurveyinRwandawasundertakenbytheteamoftheInstitut National dtudes Agronomiques au Congo (INEAC), beginning in 1955 at RubonaStation(Figure 1).AfterIndependence(1962),INEACactivitieswerecontinuedbytheInstitut des Sciences Agronomiques du Rwanda (ISAR), which wasintegratedin2012intotheRwandaAgricultureBoard(RAB).By1963,themajorsoiltypesofthecountryhad

    been described (VanWambeke, 1963). In the 1980s,almost all soil knowledge acquired by the INEAC-ISARteamwassynthesizedintoasoilassociationmapat a scale