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Edith Taleisnik

Raúl S. Lavado Editors

Saline and Alkaline Soils in Latin America

Natural Resources, Management and Productive Alternatives

SalineandAlkalineSoilsinLatinAmerica

EdithTaleisnik • RaúlS.Lavado

Editors

SalineandAlkalineSoils

inLatinAmerica

NaturalResources,Management andProductiveAlternatives

Editors

EdithTaleisnik

ConsejoNacionaldeInvestigaciones

CientíficasyTécnicas(CONICET)

BuenosAires,Argentina

InstitutodeFisiologíayRecursosGenéticos

Vegetales(IFRGV),InstitutoNacional deTecnologíaAgropecuaria(INTA)

CentrodeInvestigaciones Agropecuarias(CIAP)

Córdoba,Argentina

FacultaddeCienciasAgropecuarias

UniversidadCatólicadeCórdoba

Córdoba,Argentina

RaúlS.Lavado

ConsejoNacionaldeInvestigaciones

CientíficasyTécnicas(CONICET)

BuenosAires,Argentina FacultaddeAgronomía UniversidaddeBuenosAires BuenosAires,Argentina

ISBN978-3-030-52591-0ISBN978-3-030-52592-7(eBook)

https://doi.org/10.1007/978-3-030-52592-7

© SpringerNatureSwitzerlandAG2021

Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart ofthematerialisconcerned,specificallytherightsoftranslation,reprinting,reuseofillustrations, recitation,broadcasting,reproductiononmicrofilmsorinanyotherphysicalway,andtransmission orinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped.

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ThisSpringerimprintispublishedbytheregisteredcompanySpringerNatureSwitzerlandAG Theregisteredcompanyaddressis:Gewerbestrasse11,6330Cham,Switzerland

Foreword

Asworldpopulationcontinuestoexpand,globalneedforincreasedfoodproductionispushingagricultureintoregionswithlowerrainfallandsalt-affectedsoils. Thisincreasesthepressuretodevelopandextendirrigationschemesandtobring marginallandintoproduction.Soilsalinizationisbecomingmoreextensiveasa resultoflandclearingandunsustainableirrigationpractices,andisamajorcauseof landdegradation.Theneedformorefoodmeansmoredependenceonirrigation schemeswhichtypicallyresultin25–50%oftheirrigatedlandbeingsalinized. Clearingofnaturalvegetationforcroppingorgrazingbringssalttothesurface. Low-lyingcountriesaresusceptibletocoastalinundationduetorisingsealevels andextremeweathereventscausedbyglobalwarming,andacombinationof salinitypluswaterloggingisdoublydisastrous.

Thereisaclearandurgentneedforanevaluationoftheextentofsalt-affected soils,theextenttowhichtheyareexpanding,andtheirabilitytosupportagriculture andforestrywithoutfurtherlanddegradation.Iftheselandsaretobecultivated,itis imperativetheybemanagedsensitivelybyinnovativemanagement,newformsof agriculture,usingnewgeneticresources.Theseissuesapplytoallcontinents includingSouthAmerica,andmostimportantlytothethreelargecountriesinLatin America:Mexico,ArgentinaandBrazil.Thesearetheproductionmainstayforthe world’sbeefandsugar,aswellasforalargeshareofsoybean,maizeandseveral otheragriculturalcommodities.

Thisbookisavaluablecontributiontotheissuessurroundingsalinizedsoils.It istimelyasglobalfoodproductionisunderthreatfromclimatechange.Theeditors recognisedtheneedforthisbookandhaveselectedpapersfortworeasons.Oneis toprovideaholisticcoverage anintegratedperspectiveoftheissuessurrounding soilsalinity,landscapemanagement,andcropandforageproduction forthishas rarelybeenpublished.Whilesoilsalinityanditseffectsoncropproductionhave beenaddressedinalargenumberofpublicationsinspecialisedliterature,integrativeperspectivesinanycountryorcontinentarenotcommonlypublishedina singlevolume.

ThesecondrationaleforthisvolumeisthatmanykeypapersonsalinityinLatin Americaarepublishedinthelanguageofthatcountry,SpanishorPortuguese,and notreadilyaccessedbyscientistsinothercontinents.Yetthefundamentalsof managingsalinizedsoilsinLatinAmericaarethesameasinmanyothercountries orcontinentsparticularlyAustralia,AsiaandNorthAmerica.

Theeditorsofthisworkhaveastronginternationalreputationthroughtheir publicationsandparticipationatinternationalconferences.Botheditorsarefrom Argentina:Dr.EdithTaleisnikisaplantphysiologistspecialisinginsalt-tolerant foragegrasses,andDr.RaúlLavadoisasoilscientistworkingalsoonplant nutritionandsoiltoxicitiestocropproduction.Manyofthecontributorstothis bookalsohaveastronginternationalpresencewhileothersmoreoftenpublishin nationaljournalsorattendconferenceswhereSpanishorPortugueseisthecommon language.

Irecommendthisvolumeasavaluableresourceforland-usemanagers,irrigationengineers,agronomists,andalsoforcropscientistsandplantbreedersworking toincreaseproductiononsalinesoils.WhileapplyingtoallcountriesinLatin America,theprinciplesareofequalimportancetoscientistsfromNorthAmerica andothercontinents.Thisbookprovidesaperspectivethatwillallowthereaderto extendtheirunderstandingoftheissuesfacedbyagricultureonsalt-affectedland, andtheplanningoflanduseintheforeseeablefuture.

RanaMunns

SchoolofAgricultureandEnvironmentand ARCCentreofExcellenceinPlantEnergyBiology UniversityofWesternAustralia

Perth,Australia

CSIROAgricultureandFood Canberra,Australia

Preface

LatinAmericaisaculturalentityextendingfrom23°38′4.2″ NinNorthAmerica,to thesouthernmosttipofSouthAmerica,at59°29′20″ S.Itisavastarea,spanning for19.2millionkm2 andhomeforapproximately650millioninhabitants.Spanish andPortuguesearethemostwidelyusedlanguagesintheregion,whileEnglish, FrenchandDutcharealsospokeninsomecountries.Thisextensiveterritoryfeaturesnotjustahugevarietyofclimatesandsoils,itincludestheoneoftheworld’s driestregions(theAtacamadesert),thelongestcontinentalmountainrange(the Andes),theAmazonjungle,oneofthelargestwetlandsoftheworld(theBrazilian Pantanal),aswellasextensivefertileplains(theArgentinepampasandthe campos).

Soilsalinityandalkalinityareconcerningenvironmentalconstraintsandare foundindiverseenvironmentsthroughouttheregion.Innon-irrigatedaridand semi-aridzones,verysalinesoilssupportnaturallyadaptedvegetation.Salinesoils alsooccurinirrigatedareasinthosezones,whereintensiveagricultureispracticed. Theexistenceofsodicsoilsisregisteredmainlyinhumidandsub-humidregions andhasspreadundertheeffectsofcomplementaryirrigation,particularlywhen poor-qualitywaterisused.Ontheotherhand,agriculturalexpansioninrecent years,fueledbyincreasedworlddemandforsoybeans,hasledtoextensiveforest clearingand,insomeareas,consequentsoilsalinization.Soilsalinityandalkalinity havewell-documentednegativeimpacts,thatstemfromthesusceptibilityofplants ingeneral,andspeci ficallycropplants,totheseconditions.Theadverseconsequencesforcropyieldandqualitygenerate,inturn,socialandeconomicpenalties, immediatelyaffectingthecommunitiesestablishedinthoseenvironments,and, evidently,societyasawhole.Challengesposedbythosepenaltieshavestimulated localresearchendeavorstoovercomethem.

Whilesoilsalinityanditseffectshavebeenaddressedinalargenumberof publicationsinspecializedliterature,anintegratedperspectiveinLatinAmericahad notbeenpresentedpreviously.Thechaptersinthisbookaimatprovidingsuch perspective,andthishasbeenoneofthepurposesofthispublication.Thesecond purposeofthisbookhasbeentoprovideanentrywaytoalargebodyofknowledge developedonsalinity-relatedproblems,oftenpublishedlocallyineachcountry.

Thus,anumberofcasestudiesisincluded,supportedbyreferencestoworkpublishedinSpanishorPortuguese,whichisoftennotregisteredbyforeignreaders. Together,the106contributingauthorstothisvolumeprovideadynamicperspectiveonsalinityandalkalinityproblemsandapproachesinLA.

Thebookhasbeenorganizedin fiveparts.The firstprovidesaglobaloverview onthesalinitysituationinLA,particularlyinirrigatedareas.Throughacasestudy inBrazil,itaddressessomeofthecomplexsocialoutcomesofsoilandwater salinity.Thesecondpart,focusesonsoils,water,agricultureandmanagementin aridenvironments,whilethethirdpartaddressesthesametopicsinhumidenvironments.Thefourthpartconsidersplantresourcesfromsalinesoilsandtheir contributiontoproductiveandecologicalsustainability.Thechapterinthe fifthpart providesaperspectiveonexpectedchangesinvulnerableenvironmentsunder globalclimatechangeandpotentialmanagementandresearchactionstomitigate them.

TheinformationabouttheactualareaoccupiedbysaltaffectedsoilsinLatin Americaisrelativelyuncertain.Mostdataaredifferentestimatesfromvaried sourcesmadealong50yearsandtherefore,itisnotuncommontoarriveatdifferent numberswhenauthorsquotepapersorreportsshowingrelativelydifferentinformation.Thevariabilityofestimationsoftheextentofsalineandsalinizedareas revealsaweaknesswhichhasnotbeenovercomeyet.Thereisanurgentneedto updateandcoordinatethedatathattheseestimatesarebasedupon.Thishighlights oneofthechallengesthatmustbeaddressedifconcertedactionstodealwith salinityintheregionareinitiatedinthefuture.Whilesalinity(andsodicity)usually translateintolocalsocialimpacts,long-term,extra-regionalpoliciesarerequiredto protectvulnerableecosystemsandtheircommunitiesfromexpectedeffectsof large-scaleland-usechanges.

Thevolumeisintendedforanacademicandalsoatechnicalaudience.The editorsareindebtedtoalltheauthorsthatverygenerouslycontributedwiththeir knowledgeandexpertisetothisbook,andrespondedpositivelytoeditorialcommentsandsuggestions.Weacknowledgetopiccoverhasbeeninvoluntarilypartial andextendourapologiestonumerousresearchgroupsthatworkinthegeneral subjectofthisbook,andwhosecontributionshavenotbeenincluded.Itisourhope that,asareaction,thispublicationwillstimulateeffortsforincreasingthevisibility ofallworkrelatedtosalinityinLatinAmerica.

CommonlyUsedUnitsandTheirConversion

Surface

1km2 =100ha=247.1acre

1ha=2.471acre

Valuesforgeographicalareasareusuallyexpressedinkm2,whilehaisusedfor agronomicorproductiveareas

1m2 =1.196sqyd

Mass

1kg=0.001t=2.20462lb

Salinity(ElectricalConductivity EC)

1dS/m=1mS/cm=1000 µS/cm=1mmho/cm

1dS/m 10meq/l

Concentration

1mg/l=1ppm

1mmolc/l=1meq/l

1dag/kg=1%

1cmolc/kg=1meq/100g

TheSalineEnvironmentsinLatinAmerica.OverviewandSocial Approach

OverviewofSalt-AffectedAreasinLatinAmerica:Physical,Social andEconomicPerspectives

3 IldefonsoPlaSentís

Environmental,Agricultural,andSocioeconomicImpacts ofSalinizationtoFamily-BasedIrrigatedAgricultureintheBrazilian SemiaridRegion ...........................................

NildodaSilvaDias,JuciremaFerreiradaSilva, MariaAlejandraMoreno-Pizani,MatheusCardimFerreiraLima, JorgeFreiredaSilvaFerreira,EdnaLúciaRochaLinhares, OsvaldoNogueiradeSousaNeto,JeaneCruzPortela, MarciaReginaFariasdaSilva,MiguelFerreiraNeto, andCleytondosSantosFernandes

Soils,Water,AgricultureandManagementinArid andSemi-AridRegions

SaltAccumulationandRedistributionintheDryPlainsofSouthern SouthAmerica:LessonsfromLandUseChanges

EstebanG.Jobbágy,RaúlGiménez,VictoriaMarchesini,YésicaDiaz, DushmanthaH.Jayawickreme,andMarceloD.Nosetto StrategiesfortheUseofBrackishWaterforCropProduction inNortheasternBrazil ......................................

ClaudivanFeitosadeLacerda,HansRajGheyi, José FrancismardeMedeiros,RaimundoNonatoTávoraCosta, GeocleberGomesdeSousa,andGeovaniSoaresdeLima

37

51

71

PotentialAgriculturalUseofRejectBrinefromDesalinationPlants inFamilyFarmingAreas 101

NildodaSilvaDias,CleytondosSantosFernandes, OsvaldoNogueiradeSousaNeto,CláudioRicardodaSilva, JorgeFreiredaSilvaFerreira,FranciscoVaniesdaSilvaSá, ChristianoRebouçasCosme,AnaClaudiaMedeirosSouza, André MoreiradeOliveira,andCarlaNatanielideOliveiraBatista

SaltAffectedSoilsintheBrazilianSemiaridandPhytoremediation asaReclamationAlternative ................................. 119

MariaBetâniaGalvãoSantosFreire,FernandoJosé Freire, LuizGuilhermeMedeirosPessoa,EdivanRodriguesdeSouza, andHansRajGheyi

SalinizationinPeruvianNorthCoastSoils:CaseStudy inSanPedrodeLloc 141

NadiaR.Gamboa,AdolfoB.Marchese,andCarlosH.TavaresCorrêa EffectsofSalinityonVineyardsandWinesfromMendoza, Argentina

RosanaC.Vallone,LauraE.Martínez,FedericoG.Olmedo, andSantiagoE.Sari

Causes,Effects,andManagementofSalinityProblemsinPecan ProductioninNorthMexico ..................................

DámarisOjeda-Barrios,AdalbertoBenavides-Mendoza, AdrianaHernández-Rodríguez,LauraRaquelOrozco-Meléndez, andEstebanSanchez

SalinityinHumid,WaterloggedandFloodedEnvironments

Genesis,PropertiesandManagementofSalt-AffectedSoils intheFloodingPampas,Argentina

PerlaA.Imbellone,MiguelA.Taboada,FranciscoDamiano, andRaúlS.Lavado

Origin,ManagementandReclamationTechnologiesofSalt-Affected andFloodedSoilsintheInlandPampasofArgentina

MiguelA.Taboada,FranciscoDamiano,José M.Cisneros, andRaúlS.Lavado

191

209

Salt-AffectedSoilsofPantanalWetland ......................... 229

SheilaA.C.FurquimandThiagoT.Vidoca TemperateCoastalSaltMarshSoils EffectsofGrazing andManagementAlternatives ................................

CarlaE.DiBella,AdrianaM.Rodríguez,MiguelA.Taboada, andAgustínA.Grimoldi

LimitationsandSustainableManagementofHalohydromorphicSoils oftheSantaFeProvince,Argentina 269

SilviaImhoffandJosé LuisPanigatti

EffectsofSupplementaryIrrigationonSoilsandCropsinHumid andSub-humidAreasinthePampasRegionofArgentina 285 CarinaRosaAlvarez,HelenaRimskiKorsakov,andMartínTorresDuggan

ConceptualandPracticalFrameworktoAddressGypsum ManagementinSalt-AffectedSoils .............................

MartínTorresDugganandMónicaB.Rodríguez

PlantResourcesfromSalineSoilsandTheirContribution toEcologicalSustainability

295

EcologicalRestorationandProductiveRecoveryofSaline EnvironmentsfromtheArgentineMonteDesertUsing NativePlants 313

PabloE.Villagra,CarlosB.Passera,SilvinaGreco,CarmenE.Sartor, PabloA.Meglioli,JuanA.Alvarez,SofíaDágata,CeciliaVegaRiveros, LilianaI.Allegretti,MaríaEmiliaFernández,BárbaraGuida-Johnson, NerinaB.Lana,andMarianoA.Cony

NativeandNaturalizedForagePlantGeneticResources forSalineEnvironmentsoftheSouthernmostPortion oftheAmericanChaco ...................................... 339

José F.Pensiero,JuanM.Zabala,LorenadelR.Marinoni, andGeraldinaA.Richard

PlantToleranceMechanismstoSoilSalinityContribute totheExpansionofAgricultureandLivestockProduction inArgentina 381

EdithTaleisnik,AndrésAlbertoRodríguez,DoloresA.Bustos, andDaríoFernandoLuna

GeneticImprovementofPerennialForagePlantsforSalt Tolerance 399 GustavoE.Schrauf,FlaviaAlonsoNogara,PabloRush,PabloPeraltaRoa, EduardoMusacchio,SergioGhio,LucianaCouso,ElenaRamos, MatíasF.Schrauf,LisandroVoda,AndreaGiordano,JulioGiavedoni, José F.Pensiero,PabloTomas,JuanM.Zabala,andGermánSpangenberg

AntioxidantMechanismsInvolvedintheControlofCowpeaRoot GrowthUnderSalinity ...................................... 415 JosemirMouraMaia,CristianeE.C.Macedo,IvanicedaSilvaSantos, YuriLimaMelo,andJoaquimA.G.Silveira

Lotusspp.:AForeignerthatCametoStayForever:Economic andEnvironmentalChangesCausedbyItsNaturalization intheSaladoRiverBasin(Argentina)

AmiraSusanaNievaandOscarAdolfoRuiz

FuturePerspectives

ClimateChangeandSalinity-VulnerableEcosystems inLatinAmerica .......................................... 449

ErnestoF.ViglizzoandM.FlorenciaRicard

Index

EditorsandContributors

AbouttheEditors

EdithTaleisnik graduatedasabiologistfromtheNationalUniversityofCórdoba, inArgentina.ShehasanM.Sc.fromStanfordUniversity,USA,andaPh.D.from theBenGurionUniversityoftheNegev,inIsrael.SheiscurrentlyaResearcherat theNationalResearchCouncilofArgentina(CONICET),affiliatedtotheNational InstituteforAgriculturalTechnology(INTA),aprofessorattheCatholicUniversity ofCórdoba,ArgentinaandamemberoftheArgentineAcademyofAgronomyand Veterinary(ANAV).Shehasbeenagranteeand,later,anactivecollaboratorand memberoftheBoardofTrusteesoftheInternationalFoundationforScience(IFS). Herresearchfocusesonmechanismsofplantresponseandtolerancetosaltand alkaliconditions,mainlyinforagegrasses.ShehastaughtundergraduatePlant PhysiologycoursesforAgronomystudentsandnationalandinternationalgraduate coursesonplantsalttolerancemechanisms.Alongwithothercolleagues,she participatedinthecreationoftheArgentineNationalSalinityNetwork(RAS,Red ArgentinadeSalinidad)andpresidedtheinstitutionfrom2005to2016.

RaúlS.Lavado graduatedfromtheCollegeofAgronomy,UniversityofBuenos Aires,Argentina(1968).Hehashadtraining/postdoctoralexperiencesinSpain (1971),Canada(1979)andUSA(1980).From1993to2010hewasFullProfessor, andfrom2010,heisDistinguishedProfessorattheCollegeofAgronomy, UniversityofBuenosAires.HeisaCONICET(NationalResearchCouncilof Argentina)researcherandhasbeentheDirectoroftheInstituteofAgriculturaland EnvironmentalBiosciences INBA(2008–2014).

Hisresearchfocusesmainlyinsoil,particularlysoilsalinization,soilfertilityand soilcontaminationandhaspublishedmorethan250researchpapers,severalbooks andchapters,technologicalpublicationsandextensionmaterials.Hehasbeen advisorofnumerousMasterandPh.D.theses.HehasbeenAssociatedEditorofthe JournalofSoilandWaterConservation(USA)andotherjournals,andfounder oftheArgentineanjournalCienciadelSuelo.Heisanhonorarymemberofthe

ArgentineSocietyofSoilScienceandreceivedtheSantelisesAwardfromtheSoil ScienceSocietyofLatinAmerica,forthebook “SoilsofArgentina”.Hewasthe presidentoftheRedArgentinadeSalinidad(RAS)from2016to2019.

Contributors

LilianaI.Allegretti FacultaddeCienciasAgrarias,UniversidadNacionalde Cuyo,Mendoza,Argentina; InstitutoArgentinodeInvestigacionesdelasZonas Áridas(IADIZA) CONICET Mendoza,Mendoza,Argentina

CarinaRosaAlvarez SoilFertilityandFertilizer,SchoolofAgronomy, UniversityofBuenosAires,BuenosAires,Argentina

JuanA.Alvarez InstitutoArgentinodeNivología,GlaciologíayCiencias Ambientales CONICETMendoza,Mendoza,Argentina; FacultaddeCienciasAgrarias,UniversidadNacionaldeCuyo,Mendoza,Argentina

AdalbertoBenavides-Mendoza DepartamentodeHorticultura,Universidad AutónomaAgrariaAntonioNarro,Saltillo,Mexico

DoloresA.Bustos InstitutodeFisiologíayRecursosGenéticosVegetales (IFRGV),CentrodeInvestigacionesAgropecuarias(CIAP),InstitutoNacionalde TecnologíaAgropecuaria(INTA),Córdoba,Argentina

José M.Cisneros FacultaddeAgronomíayVeterinaria,UniversidadNacionalde RíoCuarto,RíoCuarto,Argentina

MarianoA.Cony InstitutoArgentinodeInvestigacionesdelasZonas Áridas (IADIZA) CONICETMendoza,Mendoza,Argentina

ChristianoRebouçasCosme CenterforAgrarianSciences,Departmentof AgronomicandForestSciences,FederalRuralUniversityoftheSemi-Arid (UFERSA),Mossoró,Brazil

RaimundoNonatoTávoraCosta UniversidadeFederaldoCeará,Fortaleza, Ceará,Brazil

LucianaCouso FacultaddeAgronomía,CátedradeGenética,Universidadde BuenosAires,BuenosAires,Argentina

JuciremaFerreiradaSilva CenterforAgrarianSciences,Departmentof AgronomicandForestSciences,FederalRuralUniversityoftheSemi-Arid (UFERSA),Mossoró,Brazil

MarciaReginaFariasdaSilva UniversityoftheRioGrandedoNorteState, Mossoró,Brazil

CláudioRicardodaSilva FederalUniversityofUberlândia,Uberlândia,Minas Gerais,Brazil

NildodaSilvaDias CenterforAgrarianSciences,DepartmentofAgronomicand ForestSciences,FederalRuralUniversityoftheSemi-Arid(UFERSA),Mossoró, Brazil

JorgeFreiredaSilvaFerreira UnitedStatesSalinityLaboratory(USDA-ARS), Riverside,CA,USA

FranciscoVaniesdaSilvaSá CenterforAgrarianSciences,Departmentof AgronomicandForestSciences,FederalRuralUniversityoftheSemi-Arid (UFERSA),Mossoró,Brazil

IvanicedaSilvaSantos LaboratoryofPlantProductionTechnologies, UniversidadeEstadualdaParaíba,Catolé doRocha,Paraíba,Brazil

SofíaDágata FacultaddeCienciasAgrarias,UniversidadNacionaldeCuyo, Mendoza,Argentina

FranciscoDamiano InstitutodeClimayAgua,InstitutoNacionaldeTecnología Agropecuaria(INTA),Hurlingham,BuenosAires,Argentina

ClaudivanFeitosadeLacerda UniversidadeFederaldoCeará,Fortaleza,Ceará, Brazil

GeovaniSoaresdeLima UniversidadeFederaldeCampinaGrande,Pombal, Paraíba,Brazil

José FrancismardeMedeiros UniversidadeFederalRuraldoSemi-Árido, Mossoró,RioGrandedoNorte,Brazil

André MoreiradeOliveira CenterforAgrarianSciences,Departmentof AgronomicandForestSciences,FederalRuralUniversityoftheSemi-Arid (UFERSA),Mossoró,Brazil

CarlaNatanielideOliveiraBatista CenterforAgrarianSciences,Departmentof AgronomicandForestSciences,FederalRuralUniversityoftheSemi-Arid (UFERSA),Mossoró,Brazil

EdivanRodriguesdeSouza AgronomyDepartment,FederalRuralUniversityof Pernambuco(UFRPE),Recife,Pernambuco,Brazil

GeocleberGomesdeSousa UniversidadedaIntegraçãoInternacionalda LusofoniaAfro-Brasileira,Redenção,Ceará,Brazil

OsvaldoNogueiradeSousaNeto MultidisciplinaryCenterofAngicos, UFERSA,Angicos,Brazil

LorenadelR.Marinoni ProgramadeDocumentación,Conservacióny Valoraci óndeLaFloraNativa(PRODOCOVA),FacultaddeCienciasAgrarias, UniversidadNacionaldelLitoral(FCA-UNL),Esperanza,SantaFe,Argentina

CarlaE.DiBella IFEVA-CONICET,FacultaddeAgronomía,Universidadde BuenosAires,BuenosAires,Argentina; CátedradeForrajicultura,DepartamentodeProducciónAnimal,Facultadde Agronomía,UniversidaddeBuenosAires,BuenosAires,Argentina

YésicaDiaz GrupodeEstudiosAmbientales IMASL,UniversidadNacionalde SanLuis&CONICET,SanLuis,Argentina

CleytondosSantosFernandes CenterforAgrarianSciences,Departmentof AgronomicandForestSciences,FederalRuralUniversityoftheSemi-Arid (UFERSA),Mossoró,Brazil

MaríaEmiliaFernández InstitutoArgentinodeInvestigacionesdelasZonas Áridas(IADIZA) CONICETMendoza,Mendoza,Argentina

MiguelFerreiraNeto CenterforAgrarianSciences,DepartmentofAgronomic andForestSciences,FederalRuralUniversityoftheSemi-Arid(UFERSA), Mossoró,Brazil

FernandoJosé Freire AgronomyDepartment,FederalRuralUniversityof Pernambuco(UFRPE),Recife,Pernambuco,Brazil

MariaBetâniaGalvãodosSantosFreire AgronomyDepartment,FederalRural UniversityofPernambuco(UFRPE),Recife,Pernambuco,Brazil

SheilaA.C.Furquim EnvironmentalSciencesDepartment,UniversidadeFederal deSãoPaulo(UNIFESP),Diadema-SP,Brazil

NadiaR.Gamboa DepartamentoAcadémicodeCiencias,secciónQuímica; GrupoGRIDES,PontificiaUniversidadCatólicadelPerú,Lima,Perú

HansRajGheyi FederalUniversityofRecôncavodaBahia(UFRB),Cruzdas Almas,Bahia,Brazil

SergioGhio FacultaddeAgronomía,CátedradeGenética,UniversidaddeBuenos Aires,BuenosAires,Argentina

JulioGiavedoni FacultaddeCienciasAgrarias,UniversidadNacionaldelLitoral, Esperanza,SantaFe,Argentina

RaúlGim énez GrupodeEstudiosAmbientales IMASL,UniversidadNacional deSanLuis&CONICET,SanLuis,Argentina; DepartamentodeGeología,FacultaddeCienciasFísicoMatemáticasyNaturales, UniversidadNacionaldeSanLuis,SanLuis,Argentina

AndreaGiordano FacultaddeAgronomía,CátedradeGenética,Universidadde BuenosAires,BuenosAires,Argentina; CentreforAgriBioscience,AgriBio,LaTrobeUniversity,Bundoora,VIC, Australia

SilvinaGreco FacultaddeCienciasAgrarias,UniversidadNacionaldeCuyo, Mendoza,Argentina

AgustínA.Grimoldi IFEVA-CONICET,FacultaddeAgronomía,Universidadde BuenosAires,BuenosAires,Argentina; CátedradeForrajicultura,DepartamentodeProducciónAnimal,Facultadde Agronomía,UniversidaddeBuenosAires,BuenosAires,Argentina

BárbaraGuida-Johnson InstitutoArgentinodeNivología,Glaciologíay CienciasAmbientales CONICETMendoza,Mendoza,Argentina; FacultaddeCienciasExactasyNaturales,UniversidadNacionaldeCuyo, Mendoza,Argentina

AdrianaHernández-Rodríguez FacultaddeCienciaAgrotecnológicas, UniversidadAutónomadeChihuahua,Chihuahua,Chihuahua,México

PerlaA.Imbellone InstitutodeGeomorfologíaySuelos,UniversidadNacionalde LaPlata,LaPlata,Argentina

SilviaImhoff ICiAgroLitoral,FacultaddeCienciasAgrarias,Universidad NacionaldelLitoral&CONICET,Esperanza,Argentina

DushmanthaH.Jayawickreme DepartmentofEarthScience,Southern ConnecticutStateUniversity,NewHaven,CT,USA

EstebanG.Jobbágy GrupodeEstudiosAmbientales IMASL,Universidad NacionaldeSanLuis&CONICET,SanLuis,Argentina; SARAS SouthAmericanInstituteforResilienceandSustainabilityStudies, Maldonado,Uruguay

NerinaB.Lana InstitutoArgentinodeNivología,GlaciologíayCiencias Ambientales CONICETMendoza,Mendoza,Argentina; FacultaddeCienciasExactasyNaturales,UniversidadNacionaldeCuyo, Mendoza,Argentina

RaúlS.Lavado FacultaddeAgronomía,UniversidaddeBuenosAiresandINBA CONICET/UBA,BuenosAires,Argentina

EdnaLúciaRochaLinhares MultidisciplinaryCenterofCaraúbas,UFERSA, Caraúbas,Brazil

MatheusCardimFerreiraLima DepartmentofAgroforestEcosystems, PolytechnicalUniversityofValencia,Valencia,Spain; ResearchandExtensionUnit(AGDR),FoodandAgricultureOrganizationofthe UnitedNations(FAO),Rome,Italy

DarioFernandoLuna InstitutodeFisiologíayRecursosGenéticosVegetales (IFRGV),CentrodeInvestigacionesAgropecuarias(CIAP),InstitutoNacionalde TecnologíaAgropecuaria(INTA),Córdoba,Argentina

CristianeE.C.Macedo LaboratoryofPlantBiotechnologyStudies,Universidade FederaldoRioGrandedoNorte,Natal,RioGrandedoNorte,Brazil

JosemirMouraMaia LaboratoryofPlantProductionTechnologies,Universidade EstadualdaParaíba,Catolé doRocha,Paraíba,Brazil

AdolfoB.Marchese FacultaddeCienciaseIngeniería,PontificiaUniversidad CatólicadelPerú,Lima,Perú

VictoriaMarchesini GrupodeEstudiosAmbientales IMASL,Universidad NacionaldeSanLuis&CONICET,SanLuis,Argentina

LauraE.Martínez E.E.A.INTAMendoza,Mendoza,Argentina

PabloA.Meglioli InstitutoArgentinodeNivología,GlaciologíayCiencias Ambientales CONICETMendoza,Mendoza,Argentina; FacultaddeCienciasAgrarias,UniversidadNacionaldeCuyo,Mendoza,Argentina

YuriLimaMelo LaboratoryofEcophysiologyofCultivatedPlants,Universidade EstadualdaParaíba,CampinaGrande,Paraíba,Brazil

MariaAlejandraMoreno-Pizani FaculdadePecege,Piracicaba,Brazil

EduardoMusacchio FacultaddeAgronomía,CátedradeGenética,Universidad deBuenosAires,BuenosAires,Argentina

AmiraSusanaNieva InstitutoTecnológicodeChascomús(INTECH), Chascomús,Argentina; MaxPlanckInstituteofMolecularPlantPhysiology,Potsdam,Germany

FlaviaAlonsoNogara FacultaddeAgronomía,CátedradeGenética,Universidad deBuenosAires,BuenosAires,Argentina

MarceloD.Nosetto GrupodeEstudiosAmbientales IMASL,Universidad NacionaldeSanLuis&CONICET,SanLuis,Argentina;

CátedradeClimatologíaAgrícola,FacultaddeCienciasAgropecuarias(UNER), EntreRíos,Argentina

DámarisOjeda-Barrios FacultaddeCienciaAgrotecnológicas,Universidad AutónomadeChihuahua,Chihuahua,Chihuahua,México

FedericoG.Olmedo E.E.A.INTAMendoza,Mendoza,Argentina

LauraRaquelOrozco-Meléndez FacultaddeCienciaAgrotecnológicas, UniversidadAutónomadeChihuahua,Chihuahua,Chihuahua,México

José LuisPanigatti (Deceased),InstitutoNacionaldeTecnologíaAgropecuaria (INTA),BuenosAires,Argentina

CarlosB.Passera FacultaddeCienciasAgrarias,UniversidadNacionaldeCuyo, Mendoza,Argentina

José F.Pensiero ProgramadeDocumentación,ConservaciónyValoracióndela FloraNativa(PRODOCOVA),FacultaddeCienciasAgrarias,Universidad NacionaldelLitoral(FCA-UNL),Esperanza,SantaFe,Argentina

LuizGuilhermeMedeirosPessoa AcademicUnitofSerraTalhada(UAST), FederalRuralUniversityofPernambuco(UFRPE),SerraTalhada,Pernambuco, Brazil

IldefonsoPlaSentís DepartmentofEnvironmentandSoilScience,Universityof Lleida,Lleida,Spain

JeaneCruzPortela CenterforAgrarianSciences,DepartmentofAgronomicand ForestSciences,FederalRuralUniversityoftheSemi-Arid(UFERSA),Mossoró, Brazil

ElenaRamos FacultaddeAgronomía,CátedradeGenética,Universidadde BuenosAires,BuenosAires,Argentina

M.FlorenciaRicard INCITAP-CONICET,SantaRosa,LaPampa,Argentina; FacultaddeCienciasExactasyNaturales,UNLPam,SantaRosa,LaPampa, Argentina

GeraldinaA.Richard ProgramadeDocumentación,ConservaciónyValoraci ón delaFloraNativa(PRODOCOVA),FacultaddeCienciasAgrarias,Universidad NacionaldelLitoral(FCA-UNL),Esperanza,SantaFe,Argentina

HelenaRimskiKorsakov SoilFertilityandFertilizer,SchoolofAgronomy, UniversityofBuenosAires,BuenosAires,Argentina

PabloPeraltaRoa FacultaddeAgronomía,CátedradeGenética,Universidadde BuenosAires,BuenosAires,Argentina

AndrésAlbertoRodríguez ConsejoNacionaldeInvestigacionesCientífi casy Técnicas(CONICET),BuenosAires,Argentina; LaboratoriodeEstrésAbióticoyBióticoenPlantas,UnidaddeBiotecnología1, InstitutoTecnológicodeChascomús(INTECH),Chascomús,Argentina

AdrianaM.Rodríguez CátedradeForrajicultura,DepartamentodeProducci ón Animal,FacultaddeAgronomía,UniversidaddeBuenosAires,BuenosAires, Argentina

MónicaB.Rodríguez FacultaddeAgronomía,UniversidaddeBuenosAires, BuenosAires,Argentina

OscarAdolfoRuiz InstitutoTecnológicodeChascomús(INTECH),Chascomús, Argentina

PabloRush FacultaddeAgronomía,CátedradeGenética,UniversidaddeBuenos Aires,BuenosAires,Argentina

EstebanSanchez CONACYT-CentrodeInvestigaciónenAlimentaci ónY DesarrolloA.C.CoordinaciónDelicias,FraccionamientoVencedoresdelDesierto, Delicias,Chihuahua,México

SantiagoE.Sari E.E.A.INTAMendoza,Mendoza,Argentina

CarmenE.Sartor FacultaddeCienciasAgrarias,UniversidadNacionaldeCuyo, Mendoza,Argentina

GustavoE.Schrauf FacultaddeAgronomía,CátedradeGenética,Universidadde BuenosAires,BuenosAires,Argentina

MatíasF.Schrauf FacultaddeAgronomía,DepartamentodeMétodos Cuantitativos,UniversidaddeBuenosAires,BuenosAires,Argentina

JoaquimA.G.Silveira LaboratoryofPlantMetabolism,UniversidadeFederaldo Ceará,Fortaleza,Ceará,Brazil

AnaClaudiaMedeirosSouza CenterforAgrarianSciences,Departmentof AgronomicandForestSciences,FederalRuralUniversityoftheSemi-Arid (UFERSA),Mossoró,Brazil

GermánSpangenberg CentreforAgriBioscience,AgriBio,LaTrobeUniversity, Bundoora,VIC,Australia

MiguelA.Taboada InstitutodeSuelos,InstitutoNacionaldeTecnología Agropecuaria(INTA),CONICET,BuenosAires,Argentina

EdithTaleisnik ConsejoNacionaldeInvestigacionesCientíficasyTécnicas (CONICET),BuenosAires,Argentina; InstitutodeFisiologíayRecursosGenéticosVegetales(IFRGV),Centrode InvestigacionesAgropecuarias(CIAP),InstitutoNacionaldeTecnología Agropecuaria(INTA),Córdoba,Argentina; FacultaddeCienciasAgropecuarias,UniversidadCatólicadeCórdoba,Córdoba, Argentina

CarlosH.TavaresCorrêa DepartamentoAcadémicodeHumanidades,sección GeografíayMedioAmbiente;GrupoGRIDES,Pontifi ciaUniversidadCatólicadel Perú,Lima,Perú

PabloTomas FacultaddeCienciasAgrarias,UniversidadNacionaldelLitoral, Esperanza,SantaFe,Argentina

MartínTorresDuggan Tecnoagro,BuenosAires,Argentina

RosanaC.Vallone E.E.A.INTAMendoza,Mendoza,Argentina; SoilScienceDepartment,NationalUniversityofCuyo(UNCuyo),Mendoza, Argentina

CeciliaVegaRiveros InstitutoArgentinodeNivología,GlaciologíayCiencias

Ambientales CONICETMendoza,Mendoza,Argentina

ThiagoT.Vidoca GeographyDepartment,UniversidadedeSãoPaulo(USP),São Paulo-SP,Brazil

ErnestoF.Viglizzo INCITAP-CONICET,SantaRosa,LaPampa,Argentina; FacultaddeCienciasEmpresariales,UniversidadAustral,BuenosAires,Argentina

PabloE.Villagra InstitutoArgentinodeNivología,GlaciologíayCiencias Ambientales CONICETMendoza,Mendoza,Argentina; FacultaddeCienciasAgrarias,UniversidadNacionaldeCuyo,Mendoza,Argentina

LisandroVoda FacultaddeAgronomía,CátedradeGenética,Universidadde BuenosAires,BuenosAires,Argentina

JuanM.Zabala ProgramadeDocumentación,ConservaciónyValoracióndela FloraNativa(PRODOCOVA),FacultaddeCienciasAgrarias,Universidad NacionaldelLitoral(FCA-UNL),Esperanza,SantaFe,Argentina

OverviewofSalt-AffectedAreasinLatin America:Physical,SocialandEconomic Perspectives

IldefonsoPlaSentís

Abstract InLatinAmérica(LA),aswellasinotherpartsoftheworld,salt-affected soils,bothsalineandsodic,arefoundunderdrylandandirrigatedconditions,with negativeconsequencesfortheenvironment,forcropproductivityandforanimal andhumanhealth.Additionally,sometropicalcoastalandriverdeltaareashave developedsalineacidsoils.Mostofthesalt-affectedareashaveextendedunder naturalconditions.However,thedevelopmentofaffectedareasasaresultofhumaninducedprocesses,mainlyassociatedwithhydrologicalchangescausedbyirrigation anddrainagepractices,isincreasing.Thisprocessnegativelyaffects,sometimes irreversibly,theproductivecapacityofsomeofthebestsoilsinmanycountries ofLA,withimportanteconomicimpactsandsocialconsequences.Althoughrecent estimatesoftheextensionanddistributionofhuman-inducedsalt-affectedsoilsinLA arenotavailable,thereareclearindicationsthatbothproblems,salinityandsodicity, underdrylandandirrigatedconditions,havebeenandarepresentlyincreasingin manyLAcountries.Acountry-by-countryoverviewofsoilandwatersalinityand sodicityispresentedinthischapter,focusingmainlyonirrigationanddrainage problems.

Keywords

1Introduction

Ingeneral,allsoilswithproblemsdirectlyorindirectlyderivedfromtheamountand kindofsaltsinsolutionarereferredtoas“salt-affectedsoils”(PlaSentís 1983).Saltaffectedsoils,bothsalineandsodic,maydevelopbothunderdrylandandirrigated conditions(PlaSentís 2014, 2015), negativelyaffectingphysicalandchemicalsoil properties,cropproductionandanimalandhumanhealth.

I.PlaSentís(B) DepartmentofEnvironmentandSoilScience,UniversityofLleida,Lleida,Spain

e-mail: ildefonso.pla@udl.cat

©SpringerNatureSwitzerlandAG2021

E.TaleisnikandR.S.Lavado(eds.), SalineandAlkalineSoils inLatinAmerica, https://doi.org/10.1007/978-3-030-52592-7_1

Salt-affectedsoilsmaydevelopthroughnaturalprocesses(primarysalinization) orcanbeinducedbyhumanintervention(secondarysalinization).Theprocessesof secondarysalinizationbecomeacceleratedwhenthesoilwaterregimeisdrastically changedwiththeintroductionofirrigationwithdrainagerestrictions(Fig. 1).

Theproblemsofsecondarysoilsalinityaremostwidespreadinaridandsemiaridregionsbutsalt-affectedsoilsalsooccurextensivelyinsub-humidandhumid climates,andinthecoastalregions,whereshallowsalineandsodicgroundwaters causelarge-scalesalinizationandsodification.Themostserioussalinityproblems arelocatedintheirrigatedaridandsemiaridregions,yetitisintheseregionsthat irrigationisessentialtoincreaseagriculturalproductiontosatisfyfoodrequirements. Soilsalinityisalsoaseriousprobleminareaswheregroundwaterofhighsaltcontent isusedforirrigation.Differencesintheamountandkindofsaltsaccumulatedinthe soilsolutionresultin“salt-affectedsoils”ofvariedchemical,physicalandphysicochemicalproperties,withdifferentmanagementstrategiesfortheirprevention,use andreclamation.

Salinesoilsarethosewherethesaltcontentandosmoticpotentialofthesoil solutionpreventthecropfromabsorbingalargeproportionofthesoilwateranddo

Fig.1 Commonfactorsandprocessesinthedevelopmentofsalt-affectedsoilsunderdrylandand irrigatedconditions.(SOMORE:PlaSentís 2002, 2006)(SALSODIMAR:PlaSentís 1988, 1997)

notshowanydirecteffectonthesoilphysicalproperties.Themainconsequenceis thepartialorcompletereductioninplantgrowthduetophysiologicalwaterdeficits.

SodicsoilsaredominatedbyNa(andbyMginsomecases)ontheircation exchangesites.Sodicityproduceschangesonthesoil´sphysicalproperties,bothby dispersionandpluggingofsoilporesbythemovingclayparticlesandbysoilpore blockagebyswellingclays.Whensurfacesoildisperses,theclayandsiltparticles clogsurfacepores,resultinginsoilsealing,reducedinfiltrationandsurfacewaterlogging.Thisaffectslanduseandplantgrowthbydecreasingthepermeabilityof waterandairthroughthederivedsoilwaterloggingandimpedingrootpenetration. Traditionally,the“sodicsoils”havebeencalled“alkalisoils,”althoughtheseinclude onlythesodicsoilswithpresenceandaccumulationofNabicarbonatesandcarbonatesandpHhigherthan8.5–9.0.Thereareothersoilswithpropertiesofsodicsoils withlowerpHandlowerrelativelevelsofNathantheso-calledalkalisoils(Pla Sentís 1968, 2015).

Theexpansionofirrigatedagricultureisnecessaryforthesustainableproduction ofthefoodrequiredbyagrowingworldpopulation.Suchdevelopmentislimited bytheincreasingscarcityandlowqualityofavailablewaterresourcesandbythe competitiveuseofthoseresourcesforotherpurposes.Therearealsoincreasingproblemsofcontaminationofsurfaceandgroundwaters.Takingalsointoconsideration thehighinvestmentsrequiredforthedevelopmentofirrigatedagriculture,thedegradationofirrigatedlandsthroughsoilsalinizationandsodificationbecomesignificant problemsfromtheeconomic,socialandenvironmentalpointsofview(Qadiretal. 2014).

Inmanycountries,irrigationhasbecomeaveryimportantcomponentoffood production,sometimesthemostimportant.Theirrigatedareaintheworldhas increasedfrom50millionhain1900to100millionhain1950andto350million hainrecentestimates(FAO-ITPS-GSP 2015).However,theyearlylossofproductivity,mainlyduetosalinizationofirrigatedlands,amountsto1.5millionha,and salinityproblems,ofvariousdegrees,presentlyaffectalmost25–50%(depending ontheevaluations)ofalltheirrigatedland(Abroletal. 1988).Althoughsalinityaffectedareasaremuchsmallerthanthoseaffectedbyotherdegradationprocesses likeerosion,thesocial,economicandenvironmentaleffectsareofthesamemagnitude,asaconsequenceofthehighvalueandproductivityofirrigatedlandsandtheir coincidencewithareasoflargeurbanandindustrialdevelopment.Preciseinformationandrecentestimatesoftheworldextensionanddistributionofsalt-affectedsoils donotexist.Oneofthemostrecentreports(FAO-ITPS-GSP 2015),mainlybased onoutdatedinformationaboutthedistributionofsalt-affectedsoilsindrylandsin differentcontinents,indicatesthatmorethan107 km2 oftheworldsurfacearecovered bysalt-affectedsoils,40%withsalinesoilsand60%withsodicsoils.Theestimations ofareasaffectedbysecondarysalinizationareevenlessaccurateandrangefrom0.6 to1millionkm2 .Tothis,approximately0.3millionkm2 ofhuman-induceddryland salinityandsodicityshouldbeadded(Marshall 1995).Someoftheseestimations areoftentheresultofsimpleexpertjudgment,orofdatawhichhavebeenobtained andinterpretedbydifferentmethods(Oldemanetal. 1991).

2.1GeneralAnalysis

LatinAmericaisavastandheterogeneousregion.Itcomprisescountrieswithdiverse availabilityofnaturalresourcesandeconomies.Estimationsoftheextensionand distributionofsalt-affectedsoilsinLAarenotveryupdatedorpreciseandpartially basedonlyonexpertjudgment.Oldemanetal.(1991)estimatedthatabout7 × 105 km2 areaffectedbysalinityand6 × 105 km2 bysodicity,givingatotalextensionof 1.3 × 106 km2 (i.e.,130millionha).ThetotalirrigatedareainLAamountsto25–30millionha.Whilesomeoftheirrigatedareasinlargetomediumproductionunits areusedforindustrialandcommercialcropslikesugarcane,rice,cotton,etc.,irrigatedareasinsmallholdersproductionunitspresentlyproduce30–70%ofthelocally consumedfood,dependingontheregionorcountry.Itisestimatedthat25–50%of thatareaisaffectedbyhuman-inducedsecondarysalinizationandsodification.To this,itisnecessarytoadd4–5millionhaofhuman-induceddrylandsalt-affected (mostlysodic)soils.

Mostofthesecondarysalt-affectedsoilsinLAdevelopedunderirrigationare partiallyaconsequenceoflowirrigationwaterquality,butmainlyduetononefficientwatermanagementandpoordrainageconditions.Drylandsalinityand sodicityusuallydevelopinlargeplainsandvalleys,poorlydrained,withshallow salineorsodicgroundwatersmainlypromotedbylanduseandlandcoverchanges andbyovergrazing(Lavadoetal. 1990;PlaSentís 2014;Taboadaetal. 2017). Usually,human-inducedsalt-affectedsoilsdevelopedunderaridtosemiaridclimates aresaline,andthosedevelopedundersub-humidtohumidclimatesaresodic(Fig. 2). Besides,insomecoastalandswampyareasanddeltasintropicalLA(Venezuela, Colombia,Brazil),salineacidsoilshavedeveloped(Fig. 2).Theyhavedeveloped afterdrainageoffluvial-marinesedimentsdepositedincontinuouslyfloodedsaline environments(Pons 1973;PlaSentísandFlorentino 1985).

Researchaboutsalt-affectedsoilsflourishedinthe1960–1980period,when salinityresearch(basicandapplied)andevaluationwereactiveatdifferentlevelsin mostcountries.Oneresultofthisactivitywastheoccurrenceofimportantregional conferences,likethe“VIIIReuniónLatinoamericanadeFitotecnia”(Bogotá, Colombia),whichheldaspecialsessiondedicatedtosalt-affectedsoilsinLA(Pla Sentís 1971),andthe“InternationalWorkshoponSalt-AffectedSoilsinLatinAmerica”heldinMaracay(Venezuela)(PlaSentísandFlorentino 1985),whereadvances inresearchandevaluationofsalt-affectedsoilsinLAuptothatdatewerereviewed. Morerecently,inafewLAcountries,researchhasbeenactivatedagain.Seven salinityconferenceshavebeenheldsince2005inArgentinaandthreeinBrazil.In 2019,theFirstLatinAmericanSalinitySymposiumwasheldinFortaleza,Brazil. SeveralbooksonregionalsalinityissueshavebeenpublishedinSpanishandin Portuguese(Taleisniketal. 2008;Gheyietal. 2016,TaleisnikandLavado 2017).In NorthernBrazil,aNationalInstituteofSalinityScienceandTechnology(INCTSal) wascreated.

Fig.2 Mostcommonconditionsleadingtothedevelopmentofdifferentkindsofsaline,sodicand salineacidsoils,underirrigatedanddrylandconditions,inLatinAmerica.AdaptedfromPlaSentís (2015)

Acountry-by-countryoverviewofsoilandwatersalinityandsodicityproblems inLAfollows.Somecountriesarenotincludedinthisoverview,becausewehave notbeenabletofindreferencesshowingimportantprocessesofsoilsalinizationin them.

2.2SalinityinLACountries

2.2.1NorthAmerica

México

MéxicoistheLAcountrywiththelargestareaunderirrigation,duetotheprevailing climateconditionsandpopulationpressure.IrrigationisessentialforMexican economy,becauseitproducesabout40%ofthefood,withirrigatedcropsyields2–3 timeshigherthanthoseofrainfedagriculture.Themorecommonlyirrigatedcrops arewheat,sorghum,tomato,corn,safflower,cotton,potatoesandvariousfruitsand vegetables.Currently,Méxicohas6.5–7millionhaunderirrigation,3millionofthem in85largeirrigationsystemsandtherestinabout39,000smallholdersdispersed irrigationunits.About35%oftheirrigationwatercomesfromwellsandaquifers, manyover-exploitedandwithincreasingsalinity(onespecificcaseisanalyzedin thechapterbyOjeda-Barriosetal.inthisbook:“Causes,effectsandmanagementof salinityproblemsinpecanproductioninNorthMexico”).In85%ofthearea,furrow andfloodingirrigationsystemsareused,innonverywell-leveledlands,withvery lowwateruseefficiency(Palacios-VélezandPedraza-Oropeza 2015).Thissituation, alongwithnon-linedwaterconductionditches,poordrainageconditionsandpoor maintenanceoftheopendrains,generallyleadstorisinggroundwaterlevels.Undergrounddrainagepipeshavebeeninstalledinonlyabout80,000haofirrigatedlands. Dumpingurbansewagewaters,withsmallornotreatment,insurfacestreamsand irrigationditches,hasbecomemorefrequentinthelastdecades(SiebeandCifuentes 1995;PlaSentís 1997;Gallegosetal. 1999).

Attheendofthe1980s,thelargeirrigationdistricts,previouslyundergovernmentcontrol,becamecontrolledbyoperatorassociations.Sincethen,someofthe irrigationcontrolanddrainageinfrastructureshavenotbeenwellmaintained,and thepreviousmonitoringandcontrolofgroundwaterlevelsandofsoilsalinitywere mostlydiscontinued.Thetechnicalassistanceandtrainingtousers,onirrigation anddrainagemanagement,decreased(Peña 1980).Thefinalconsequenceofallthe previousfactorswasaprogressivesoilsalinization(andtoasmallerextent,sodification),withreductionsincropproductivity(AnayaandNoyola 1984).Althoughthere arenoup-to-dategeneralevaluationsoftheareaswithsalt-affectedsoilsinMéxico, approximateestimationsindicatethat10–20%(0.6–1.2millionha)ofthetotalirrigatedareaareaffectedbysomedegreeofsalinityorsodicity.Insomeirrigation systemsofNMéxico,withmorearidclimateandmoresalineirrigationwater,the affectedareamayincreaseto30–40%oftheirrigatedland(Mata-Fernandezetal. 2014).Besidesthesecondarysalt-affectedsoilsinirrigatedfields,thereareabout 1millionhaofnaturalsalt-affectedlands,mainlyinclosedbasins,aridzonesand coastalareas.