<%BANNER%>

UFIR



Introduction to Best Management Practices for Phosphorus Control on Organic Soils
http://edis.ifas.ufl.edu/ ( Publisher's URL )
CITATION PDF VIEWER
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/IR00001223/00001
 Material Information
Title: Introduction to Best Management Practices for Phosphorus Control on Organic Soils
Alternate Title: Introduction to Best Management Practices for Phosphorus Control onOrganic Soils
Physical Description: Fact Sheet
Creator: Bottcher, Del
Izuno, Forrest T.
Publisher: University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
Place of Publication: Gainesville, Fla.
Publication Date: 1992
 Subjects
Subjects / Keywords: Phosphorus -- Environmental aspects -- Florida -- Everglades
Everglades Agricultural Area
Agriculture -- Environmental aspects -- Florida -- Everglades
Genre:
Spatial Coverage: Everglades Agricultural Area
 Notes
Abstract: "This BMP series was written specifically to address the concern for phosphorus control in the Everglades Agricultural Area. The information contained in the series may be applied to any agricultural area composed primarily of organic soils or Histosols. However, please be aware that this information may not be applicable to any other soil types."
Acquisition: Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Diana Hagan.
Publication Status: Published
General Note: "Original publication date December 1992. Reviewed July 2002."
General Note: "AGR51"
 Record Information
Source Institution: University of Florida Institutional Repository
Holding Location: University of Florida
Rights Management: All rights reserved by the submitter.
System ID: IR00001223:00001

Downloads
Full Text

PAGE 2

IntroductiontoBestManagementPracticesforPhosphorousControlonOrganicSoils Page2 futurerevisionsofthisBMPseries.Despitethe aforementionedlimitations,thisBMPseriesshouldbe ausefultoolinthedevelopmentofBMPplansto meettherequirementsoftheEAABMPRule. PleasenotethattheBMPsinthisBMPserieswill onlypertaintophosphorusreductions.WHATAREBMPS?BestManagementPracticesarethoseon-farm applicationsdesignedtoreducephosphoruslossesin drainagewaterstoanenvironmentallyacceptable levelwhilesimultaneouslymaintainingan economicallyviablefarmingoperationforthegrower. Practiceswhichhaveahighpotentialfornegatively impactingthefinancialprofitabilityofafarmcould not,therefore,beconsideredBMPs.Incaseswhere theeconomicpriceofimplementingcertainBMPs putsanexcessivefinancialburdenonthefarmer,such practicescouldonlybeconsideredBMPsifexternal fundswereavailabletoreturnanacceptable profitabilitytothefarm. Itisimportanttonotethattheabovedefinitionis notthesameastheonegivenintheSouthFlorida WaterManagementDistrictBMPRule.TheRule definitionisspecifictopracticesthatwillreduce phosphoruslevelsby25%.Itdoesnottakeinto accountprofitability.However,itisclearthatif profitabilityisnotmaintained,thepracticeitself cannotbemaintained.Therefore,thereaderis cautionedthatthepracticespresentedinthisBMP series,thoughlabelledasBMPs,willonlybeBMPs for your operationiftheycanbeimplementedon yourfarminaneconomicallyviablefashion.WATERQUALITYDESIGNCRITERIAFOR BMPSINTHEEAATheoveralldesigncriteriaforBestManagement Practicesimplementationshouldsimplybeto minimizetheamountofphosphorusleavingafarm. ThoughtheBMPRulehastargetedaspecificlevelof phosphorusreduction,itisintheinterestofall partiestomaximizephosphorusreductiontothe greatestextentpossible.Phosphorusreductionlevels greaterthanthe25%BMPRulecriteriawillserveto increaseEvergladesrestoration,reducecostof stormwatertreatmentareas,andenhancethe environmental/politicalimageoftheEverglades AgriculturalArea. Aspreviouslymentioned,theEAABMPRule, whichisactuallytheRegulatorysectionofthe EvergladesStormWaterImprovementManagement Plan,requiresthatby1996,BMPsreducethe phosphorusdeliveredtotheEvergladessystemfrom theEAAbytwenty-fivepercent.Thisreductionis requiredonlyforwatergeneratedwithintheEAA. Pass-throughwaterfromLakeOkeechobeetothe WaterConservationAreas(WCAs),therefore,willbe handledseparatelybythestormwatertreatmentareas. Verificationofareductioninphosphorusload willbebasedonthecomparisonofyearlyphosphorus loadmeasurementstohistoricalphosphorusload measurementsfortheyears1979-1988.Future annualloadswillbeadjustedfordifferencesinland area(landtakenoutfortheSTAs)andinrainfall variationsfromthe1979-88base-period.Inthisway, validcomparisonscanbemade. Notealsothatthephosphorusreduction comparisonscanbemadeonlyatEAAbasin outlets (S2,S3,S5-A,S6,S7,S8,andS100)becauseno historicaldataareavailableforindividualfarm discharges.CompliancewiththeBMPRulewill thereforebejudgedattheEAAbasinlevel,requiring thenetimpactofalltheBMPswithinabasinto reducephosphorusloadsbytwenty-fivepercent.For thisreason,theBMPRuleisprimarilyan implementationruleinthatitrequiresBMPplansfor eachfarmtobedevelopedandimplementedwithina giventimeschedule.FailuretoimplementBMPs wouldresultinenforcementpenalties/fines.And,if basincomplianceisnotmet,aspecificwaterquality loadstandardwillbesetforeachindividuallypermittedfarmdischargepoint.Non-complianceat thebasinlevelwillnecessitatetherevisionofeach BMPplanandadditionalBMPimplementationwith anupdatedschedulingandenforcementrequirement.UNCERTAINTYOFBMPEFFECTIVENESS RANGESEachBestManagementPracticepresentedinthis BMPseriesisprovidedwithanestimatedrangeofthe phosphorusreductionpercentageexpectedwhen implementedintheEvergladesAgriculturalArea.In usingtheseranges,itisnecessarytounderstandboth whattheyrepresentaswellastheiruncertainty.Only threeofthelistedBMPshavebeenfieldtestedand theseweretestedforonlyalimitedsetofconditions. Therefore,mostofthestatedphosphorusreduction rangeswerebasedoncorollarydataandbasic knowledgeofthephysicalandchemicalprocessesof

PAGE 3

IntroductiontoBestManagementPracticesforPhosphorousControlonOrganicSoils Page3 theEAA.ThepresentedBMPeffectiveness(% phosphorusreduction)rangesincludethisuncertainty. Theyalso,however,reflectthevariabilitiesofexisting conditionsamongfarmsintheEAA.Thatis,farms implementingaBMPforthefirsttimecanexpectto experiencethefullbenefitofthatBMP,whereas thosefarmsalreadypracticingaspecificBMPshould, ofcourse,expectnoadditionalphosphorusreduction duetocontinuedimplementationofthatBMP.As moredatabecomeavailable,theserangeswillbe narrowedappropriately.CONCENTRATIONVERSUSFLOWCONTROL FORPHOSPHORUSLOADREDUCTIONSAsstatedearlier,BestManagementPracticesare designedtoreducephosphorousloadsbyeither reducingthevolumeofwaterdischarged,reducingthe concentrationofphosphorusinthewater,orboth. TheFertilityBMPs(seefertilityBMPs)aredesigned toreducephosphorusconcentrationswhereasthe WaterManagementBMPs(seeWaterManagement BMPs)weredevelopedprimarilytoreducenetwater dischargefromthefarm,thoughsomephosphorus concentrationreductionmayberealized. TherelativeacreagetowhichvariousBMPscan beappliedisextremelyimportantfordeterminingthe basinlevelimpactofaBMP.Forexample,BMPs targetedtoreducephosphorusconcentrationswillbe mosteffectiveforhighfertilitycropsandlow oxidativesoils.Theserepresentonlyabout15%of theentireEAAbasin.Therefore,phosphorus concentrationreductionBMPswouldhavearelatively smallbasinlevelimpact.Becauseofthis,itis estimatedthatonlyabout5-15%oftheproposed25% decreasecouldbeachievedbyphosphorus concentrationreductions.Theremaining10-20% wouldhavetocomefromdrainagevolumereductions. Pleasenotethattheabovepercentagesareonly estimatedlimitsforachievingthe25%Rulecriteria andarenotthelimitsofafullyimplementedBMP program,whichpotentiallycouldproducephosphorus reductionsofupto60%.Theactualpercentage attributedtoconcentrationversusvolumereductions willdependontherelativefarm-levelselectionof BMPs.BASINRESPONSETOFARMLEVELBMPSThephosphorusreductionrangespresentedhere arefortheresponsesexpectedfromindividual farmingsystemswithonlyasinglecrop,fertility,and watermanagementsystem.Therefore,thecombined impactofBestManagementPracticesacrossalarge farmingoperationoranentirebasinmustbe correctedforthepercentageoflandthateachunique farmingsystemrepresentswithinthatlargerarea. Thefarm-scalephosphorusreductionrangesare basedonacombinedanalysisofseveralstudies. Noneofthesestudies,however,includedfarm-scale experiments.Thepresentedranges,therefore,cannot currentlybeprovenonthebasisofscientificdata. BasedonindividualBMPeffectivenessranges, IzunoandBottcher(1991)estimatedthattheoverall rangeofphosphorusreductionthatcouldbe accomplishedfortheEvergladesAgriculturalArea basinwasbetween20-60%.Thisrangereflectstheir opinionofwhatcouldbeachievedatareasonable cost(20%reductionfigure)and,inaddition,what mightberealizedatahigher,unknowncost(60% reductionfigure).Thougha40%orgreater phosphorusreductionmightreasonablybeexpected throughimplementationofBMPs,assurancescannot begiventhattheselevelscouldbeaccomplished withinourpreviouslystateddefinitionofaBMP,i.e. apracticewhichmaintainstheeconomicvitalityof thefarm.IMPACTSOFBMPSONCROPYIELDSTheBestManagementPracticespresentedinthis BMPseriesaredesignedtoimpactminimallyoncrop yields.Thereader,however,iscautionedthatdata currentlyavailableonyieldimpactsremainslimited. Therefore,anyimplementationofBMPsmustbe donewithacautionaryapproach. Sudden,large changesinfarmoperationsarenotrecommended, especiallyinregardtowaterretention.Practicesof thiskindshouldbeimplementedinastep-wise fashionsothatanunderstandingofboththenature oftheBMPaswellasitsimpactonyieldscanbe properlyassessed.Itisimportantforfarmoperators tolearnthefulloperationalresponsesofanysingle BMPformultipleconditionsbeforeattemptingto carryoutanyfurtherlarge-scaleactivities.

PAGE 4

IntroductiontoBestManagementPracticesforPhosphorousControlonOrganicSoils Page4ACCUMULATIVEEFFECTOFMULTIPLE BMPSThepresentedreductionrangesarenot necessarilycumulativeformultipleapplicationsof BMPs.TheeffectivenessofanyoneBest ManagementPracticemaybesignificantlyreducedor eliminatedbytheadditionalimplementationofany otherBMP.Also,theoperational,nutritional,and hydraulicinfluencesofanexistingBMPmustbe takenintoaccountwhenconsideringsupplementary BMPs.Thisisparticularlytrueforsame-category BMPssuchasthosedealingwithflowreduction.REDUCEDDRAINAGEVERSUSWATER SUPPLYThereissomeconcernthatwatersupplymightbe negativelyimpactedifproposedBestManagement Practicessignificantlyreducetheamountofwater beingpumpedfromtheEvergladesAgriculturalArea farmlands.ItisimportanttonotethatBMPscan onlyimpactregionalwatersuppliesiftheyincrease evapotranspiration(ET)fromthefarm.Since evapotranspirationisexpectedtoincreaseonlywhen thewaterretentionBMPsarebeingused,(andthen toincreaseonlyslightly),thequestionbecomes: "Whathappenstothewaterthatisnolongerbeing pumped?".ItwillstillbeinLakeOkeechobee becausethemajorityofthereduceddrainagewillbe directlyreflectedinreducedirrigationdemandbythe farms.ThewaterinLakeOkeechobeewillcontinue tobeavailableforregionalwatersupply.Offsetting existingEAAdrainagewaterwithpass-throughLake waterrepresentsabouta50%reductionin phosphorusloadingtothestormwatertreatment areas.Itisworthnotingthatundertheseconditions thestormwatertreatmentareaswilllikelyhave significantlyhigherETratesthanexistinglanduses, resultinginanetregionalwatersupplyloss.SUMMARYOFBMPSTable1providesasummaryoftheBest ManagementPracticespresentedinthisdocument. Asdemonstratedbythecurrentlyavailable information,a25%phosphorusreductionfromBMPs isareasonableandobtainablegoal.Evenhigher reductions,however,arepotentiallyobtainable.The tableshowshowwatermanagementBMPshavea greaterpotentialforreducingphosphorusloadsthan fertilitypractices.Itisimportanttoremember, though,thatwatermanagementBMPsprimarily achievetheirreductionsbydecreasesinwatervolume, whereasfertilityBMPshaveagreaterlikelihoodof loweringphosphorusconcentrations.SEEPAGECONTROLOnevariablewhichthefarmercannotalways controlistheamountofseepagewaterenteringtheir farmfromnearbyareaswithhigherwaterlevels.This problemismostacuteforfarmsborderingthewater conservationareas(WCAs)andLakeOkeechobee becauseofwaterelevationdifferencesofasmuchas sevenfeet. SeepagefromtheprimarycanalsintheEverglades AgriculturalAreaisalsoaproblem.Eventhough headdifferences(1-3feet)arelessthanthoseofthe LakeorofWCAs,theseepagepathsarenormally shorter.Thenatureofthesoilsandunderlyingstrata permitsasignificantamountofwatertoflow(seep) underandthroughthedikesretainingthiswater.In someregionsoftheEAA,theunderlyingmarlrockis extremelypermeablesothatifthehigherwater bodieshavecanalscutintothisformation,verylarge seepageratescanoccur.Somefarmsareforcedto continuouslypumpoutthisseepagewaterinorderto maintainoptimalwatertables. TheBestManagementPracticesRuleallowsfor seepagetoberemovedfromthephosphorus reductionrequirementsthroughavarianceoption whentheexistingconditioncanbeappropriately documented.Documentationmustinclude continuousdischargeandrainfallrecordsforthe farm.Ifyoususpectseepageisaproblem,weadvise youtocontacttheSouthFloridaWaterManagement Districttoobtainadditionaldatabeforeinitiatinga monitoringprogram. FertilityBMPsaswellassomeofthewater managementBMPscanstillworkforfarmssuffering fromexcessiveseepage.Therelativebeneficial impactoftheseBMPs,however,willbereduced becausetheexpressedBMPreductionswouldonlybe fortherainfallexcessportionofthefarm'sdischarge. Inextremecases,amajorityofthephosphorusbeing pumpedfromthefarmmayhaveoriginatedin seepagewaterwhichwillnotbeimpactedbyBMPs. Seepageratescanonlybedecreasedbythefollowing techniques:

PAGE 5

IntroductiontoBestManagementPracticesforPhosphorousControlonOrganicSoils Page5 *Reducingthehydraulicgradientbyreducinghead differences(notnormallypractical)orby increasingflowpath.Thiswouldrequire increasingdikethicknessordistancetofirstfarm canal. *Reducinghydraulicconductivityofmediainflow pathbylimitingtheextentofcutsintothemarl rockforfarmcanals/ditchesnearfarmbordersor byinstallinglowconductivitybarriers(not normallypractical). Oftenseepageratescannotbereducedandsimply mustbecontrolledbyadditionalpumping.Inthese cases,itwillbenecessaryfromamonitoring standpointtoseparatefarmdrainagedischargesfrom theseepagedischarges,inorderforatruemeasureof BMPeffectivenesstobeobtained.Insome situations, itmaybepossibletopumpaseepageinterceptor canalseparatelytoobtainseepagerates.The interceptoreffectivenessincollectingthisseepage water,however,willvaryaccordingtotheunderlaying characteristicsofthemarlrocklayer.Thebest methodofseparatingseepageflowisbyconductinga hydrologicalanalysisofthedischargerecordsin combinationwithatimeseriesofthesurrounding waterlevels.Aprofessionalengineershouldbe consultedfordetailedanalysis,butaroughestimate oftheseepageratecanbecalculatedbyaddingpump dischargeratetotheestimatedfarm evapotranspirationrateandsubtractingtheestimated irrigationrate.Thiscalculationisbestperformed duringaprolongedirrigation(dry)period.We suggestthattheseparatedflows(seepageandexcess rainfall)bereportedintheBMPRulepermitreports. Table1. ReferenceListofProposedBestManagementPracticesfortheEvergladesAgriculturalArea BMPCode/Name PhosphorusReduction Range(%)1 Crop FertilityBMPs 5-202 All CalibratedSoilTesting 0-10 0-25 Sugarcane Vegetables BandingofFertilizer 0-40 0-5 Vegetables PlantCare PreventionofMisplacedFertilizer 0-15 All SplitApplicationofFertilizerandUseofSlow ReleaseForms 0-10 All WaterManagementBMPs 20-602 MinimizingWaterTableFluctuations 0-50 All RetentionofDrainageOn-Farm 15-60 Sugarcane RetentionofVegetableFieldDrainageWaterin SugarcaneorFallowLands 20-90 Vegetables UseofAquaticCoverCrops 5-20 All CoordinatedFarmCroppingPatterns n/a All NETBASINEFFECTifallBMPsimplemented 20-602 All 1Rangesareforindividualfarmsafterconsideringuncertaintyandthevariabilityoffarm managementunlessotherwisenoted.2PhosphorusreductionrangeisforentireEAABasin.Notethattheupperlimitsarevery theoreticalandarenotexpectedtobeachievedwithoutsignificantcost.

PAGE 6

IntroductiontoBestManagementPracticesforPhosphorousControlonOrganicSoils Page6WATERMONITORINGMonitoringofthequantityandqualityofwater enteringorleavingafarm,aswellasspecificinternal waterconditionswillbeveryusefulindevelopingand refiningaBMPprogram.TheBMPRulerequires outflowsofwaterandphosphorustobemonitoredby October1993.BecausetheBMPRuleonlypertains tooutflowstoDistrictcanals,itsmonitoring requirementswillnotprovideacompletepictureof thewaterandphosphorusdynamicsonafarm. AsemphasizedthroughoutthisBMPseries,the successofanyBMPprogramwilldependheavilyon thefarmer'sknowledgeandunderstandingofthe hydraulicandphosphorusdynamicsofthefarm.The onlywaytoreallyknowifaparticularpracticeis workingistomonitoritseffects.Anappropriate monitoringprogramshouldincludewaterflow measurements,rainfall,phosphorusconcentrationsof drainageandirrigation,andin-fieldwatertablelevels. Detailsoftheequipmentandproceduresfor monitoringareprovidedintheInstituteofFoodand AgriculturalSciencesExtensionCirculars1036and 1040,entitled"AgriculturalWaterQualitySampling Strategies"and"WaterQualitySampling,Analysis, Instrumentation,andProcedures,"respectively.BESTMANAGEMENTPRACTICES: CONCLUSIONSOngoingenvironmentalconcernsforthe EvergladescontinuetorequirethattheEverglades AgriculturalAreareleasethecleanest(low phosphorus)waterpossibletothesouth.Itisinthe bestinterestofallpartiestoreducephosphoruslevels asmuchaspossible aslongastheeconomicvitalityof theagriculturalindustryisnotundermined .Webelieve thattheBestManagementPracticespresentedinthis guidecanobtaintherequiredphosphorusreductions withoutimposingsignificanteconomichardshipifthe BMPsareimplementedinthestep-wisefashion presented.Sudden,largechangesinfarming operationsarenotrecommendeduntilthegroweris fullysecureinhisexperienceintheimplementation andon-goinguseofthesepractices. AsseeninTable1,thecurrentlyavailable informationindicatesthatthe25%phosphorus reductionfromBMPsisareasonableandobtainable goalandthatevenhigherreductionsarepotentially obtainable.ThepresentedBMPsaredesignedboth toreducephosphorusconcentrationsinthedrainage wateraswellastocutbackthevolumeofdischarged water.Weexpectthatthegreatestreductionsof phosphorusfromtheEAAwilloccurduetoreduced drainagevolumes. AsuccessfulBMPprogramwillrequirefarm operatorswithintheEAAtosignificantlyincrease theirknowledgeandskills.Theywillneedtobeaware ofcropresponsestowatertablevariationsaswellas understandingdetailedhydraulicresponsesofthe watercontrolsystemstoclimaticconditions.Though anincreasedlevelofknowledgeandmanagerialskills willbeneeded,theywillmorethanlikelyimprove overallfarmefficiencyandtherebyoffsetsomeofthe costoftheBMPs.Withtheimplementationofthe BMPprogramsoutlinedinthisguide,thefuture farmingvitalityoftheEAAcanbemaintainedwhile protectingdown-streamnaturalresources.REFERENCESTheseworksarecitedthroughouttheentire guide. Bottcher,A.B.andF.T.Izuno.(Co-editors).1992. EvergladesAgriculturalArea(EAA)(Water,Soil, Crop,andEnvironmentalManagement) .Book DRAFTsubmittedtoUniversityPressesof Florida,Gainesville,FL. Bottcher,DelandDeanRhue.1983. Fertilizer Management-KeytoaSoundWaterQuality Program. IFAS,Univ.ofFla,Coop.Extension Circular816.16pp. Coale,F.J.1988."WaterTableMonitoring". SugarcaneGrowersNewsletter.2(4):1-5.Fla. CooperativeExtensionService.BelleGlade,FL. Coale,F.J.1989."SoilSampling,SoilTestingand FertilizerRecommendationsforFlorida Sugarcane". SugarcaneGrowersNewsletter. 3(1):1-4.Fla.CooperativeExtensionService. BelleGlade,FL. Deren,C.W.,G.H.Synder,J.D.Miller,andP.S. Porter.1991. ScreeningforandHeritabilityof Flood-toleranceintheFlorida(CP)sugarcane

PAGE 7

IntroductiontoBestManagementPracticesforPhosphorousControlonOrganicSoils Page7 breedingpopulation.ElsevierPublishers,The Netherlands.Euphytica56:155-160. Espinoza,L.A.1992. ResponseofCeleryto PhosphorusRateandPlacementonHistosols. MasterThesis.SoilandWaterScience. UniversityofFlorida.Gainesville,FL. Hanlon,E.A.,G.Kidder,andB.L.McNeal.1990. Soil,ContainerMedia,andWaterTesting InterpretationsandIFASStandardizedFertilization Recommendations. IFAS,Univ.ofFla,Coop. ExtensionCircular817.49pp. Izuno,F.T.andA.B.Bottcher.May1991. The EffectsofOn-FarmAgriculturalPracticesinthe OrganicSoilsoftheEAAonPhosphorusand NitrogenTransport-ScreeningBMPsfor PhosphorusLoadingsandConcentration Reductions.FinalReporttoSFWMD. Izuno,F.T.,A.B.Bottcher,andW.Davis.1992. AgriculturalWaterQualitySamplingStrategies IFASCircular1036.UniversityofFlorida. Jones,J.W.,L.H.Allen,S.F.Shih,J.S.Rogers,L.C. Hammond.A.G.Smajstrla,andJ.D.Martsolf. 1984. EstimatedandMeasuredEvapotranspiration forFloridaClimate,Crops,andSoils .IFAS Bulletin840. Malaika,N.F.andA.B.Bottcher.1988. Irrigation andDrainageManagementModelforFlorida's EvergladesAgriculturalArea.Transactionsof ASAE.31(4):1167-1172. Rhoads,F.M.andE.A.Hanlon.1990. SiteSpecific Soil-testInterpretationforSnapbean. Commun.In SoilSci.PlantAnal.21:2181-2188. Taylor,L.,F.T.Izuno,andA.B.Bottcher.1992. WaterQualitySampling,Analysis,Instrumentation, andProcedures .IFASCircular1040.University ofFlorida. Sanchez,C.A.,S.Swanson,andP.S.Porter.1990. "BandingtoImproveFertilizerUseEfficiencyof Lettuce". JournaloftheAmericanSocietyof HorticulturalScience 115(4). Sanchez,C.A,,P.S.Porter,andM.F.Ulloa.1991. "RelativeEfficiencyofBroadcastandBanded PhosphorusforSweetCornProducedon Histosols". SoilScienceSocietyofAmerica Journal,55,May-June. Snyder,G.H.,ed.1987. Agriculturalfloodingof organicsoils.InstituteofFoodandAgricultural SciencesBulletinNo.570.Gainesville,Florida. Snyder,G.H.,H.W.Burdine,J.R.Crockett,G.J. Gascho,D.S.Harrison,G.Kidder,J.W. Mishoe,D.L.Myhre,F.M.Pate,andS.F.Shih. 1978. Watertablemanagementfororganicsoil conservationandcropproductionintheFlorida Everglades.InstituteofFoodandAgricultural SciencesBulletinNo.801.Gainesville,Florida. 22pp.