Irrigation Scheduling Tables For Florida Citrus

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Title:
Irrigation Scheduling Tables For Florida Citrus
Physical Description:
Fact sheet
Creator:
Parsons, Lawrence R.
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un
Place of Publication:
Gainesville, Fla.
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Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Melanie Mercer.
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Published
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"Publication date: June 1993."
General Note:
"HS-166"

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University of Florida Institutional Repository
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University of Florida
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All rights reserved by the submitter.
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IR00004640:00001


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FactSheetHS-166 TheInstituteofFoodandAgriculturalSciencesisanequalopportunity/affirmativeactionemployerauthorizedtoprovideresearch,educational informationandotherservicesonlytoindividualsandinstitutionsthatfunctionwithoutregardtorace,color,sex,age,handicap,ornational origin.Forinformationonobtainingotherextensionpublications,contactyourcountyCooperativeExtensionServiceoffice. FloridaCooperativeExtensionService/InstituteofFoodandAgriculturalSciences/UniversityofFlorida/ChristineTaylorStephens,DeanJune1993IrrigationSchedulingTablesForFloridaCitrus1 L.R.ParsonsandR.C.J.Koo2INTRODUCTIONTOTABLESThefollowingtablesweredevelopedfromaverage soilconditionsintheridgeandflatwoods.Soil characteristicsandwaterpenetrationratescanvary withinagrove,butthesetablesapplytogeneralcitrus growingareasinFlorida. Generallyspeaking,flatwoodssoilsarefiner texturedandhavemoreorganicmaterialinthe surfacelayers.Thisgivesthemahigherwaterholding capacitybutalowerconductivity.Hence,watermoves moreslowlythroughflatwoodssoilsthancoarserridge soils. Amoistsoilhasahigherhydraulicorwater conductivitythanadrysoil.Thus,waterwillpenetrate deeperintoasoilthatisalreadypartiallywetthan willwaterthatisappliedtoadrysoil.Waterapplied toasoilat20percentdepletionwillgodeeperthan itwouldifthesoilwereat40percentdepletion. ThepointtorememberfromtheseTablesisthat atricklesystemthatisoperatedfortoomanyhours willdrivemuchofthewaterandnutrientsbelowthe maintreerootsystem. Weknowthatabout80percentoftherootsofa maturecitrustreeareinthetopthreefeetinridge sands,and98percentoftherootsareinthetop1.5 totwofeetinflatwoodssoils.Youngtreesinthe ridgewillhaveanevenhigherpercentageofrootsin thetopthreefeet.Hence,itmakessensetorunyour tricklesystemfrequentlyandnotforlongdurations. Workwithoverheadsprinklers(100percent coverage)showeditisbesttoirrigateat33percent depletioninthespringand67percentdepletionin thefall.Duringthespringandsummermonths,itis agoodideatorunmicrosprinklerstwoormoretimes aweek,exceptimmediatelyafterrainyperiods. Agoodwaytochecksoilwaterstatusandyour irrigationscheduleistousetensiometers.Unitscost $40to$45eachandareavailableatmostirrigation supplycompanies. Watermovementintothesoilwilldependonthe applicationrate.Asprayjetthatputsoutthesame gallonagewitha180patternhasanapplicationrate twiceashighasajetwitha360pattern.The180jet deliversthesameamountofwater,butcoversjust halfthesoilsurfacearea.Thefollowingtablesare basedona360spraypattern.Modificationswillneed tobemadeforspraypatternsthatarelessthan360.MICROSPRINKLERWATERPENETRATIONTable1showsestimatedwaterpenetrationfrom amicrosprinkler(10gal/hrat20psiwitha360spray pattern)intosoilintwoareaswhenappliedat20%, 30%,and40%soilmoisturedepletion. 1.ThisdocumentisFactSheetHS-166,aseriesoftheHorticulturalSciencesDepartment,FloridaCooperativeExtensionService,Instituteof FoodandAgriculturalSciences,UniversityofFlorida.Publicationdate:June1993. 2.L.R.Parsons,professorandWaterResourceSpecialist;R.C.J.Koo,RetiredHorticulturist,CitrusResearchandEducationCenter,LakeAlfred FL33850,CooperativeExtensionService,InstituteofFoodandAgriculturalSciences,UniversityofFlorida,GainesvilleFL32611. Theuseoftradenamesinthispublicationissolelyforthepurposeofprovidingspecificinformation.Itisnotaguaranteeorwarrantyofthe productsnamed,anddoesnotsignifythattheyareapprovedtotheexclusionofothersofsuitablecomposition.

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IrrigationSchedulingTablesForFloridaCitrus Page2 Table1. Estimatedmicrosprinklerwaterpenetration RIDGE Depletion% FLATWOODS Depletion% 20%30%40% 20%30% 40 % Irrigation Time PenetrationofWaterinFeet 2hr 3.0 2.2 1.5 1.0 0.7 0.5 4hr 6.04.53.0 2.01.5 1.0 6hr 10.0 7.5 5.0 4.0 3.0 2.0 8hr 16.0 12.0 8.0 6.0 4.5 3.0DRIPPERWATERPENETRATIONTable2showsestimatedwaterpenetrationfrom adripper(1gal/hr)intwoareaswhenappliedat 20%,30%,and40%soilmoisturedepletion. Table2. Estimateddripperwaterpenetration RIDGE Depletion% FLATWOODS Depletion% 20% 30% 40% 20% 30% 40 % Irrigation Time PenetrationofWaterinFeet 2hr 2.0 1.5 1.0 0.8 0.6 0.4 4hr4.43.32.2 2.01.5 1.0 6hr 7.2 5.4 3.6 3.2 2.4 1.6 8hr 10.0 7.5 5.0 4.5 3.3 2.2IRRIGATIONFREQUENCY ASSUMINGNORAINFALL YoungTreesForyoungtrees,increasedgrowthisthemain advantageofirrigatingfrequentlyforshortdurations. Theuppersoillayerwheremostoftherootsare locatedistherebykeptmoistandtreestressis minimized.Growthisoneofthefirstthingsaffected bywaterstress.Mildwaterstressslowsgrowthand moreprolongedstressstopsgrowthentirely.Theidea ofirrigatingapproximatelytwiceaweekfromMarch throughJuneforshortdurationsistokeeptheupper soilhorizonnearfieldcapacity,maximizegrowth,and minimizedeepsoilwaterloss.Table3showsa scheduledesignedtopromoteoptimumgrowthso treesreachproductionsizesoonerandbecome profitableatanearlierage. Table3. Irrigationscheduleforyoungtrees FREQUENCY (timesperweek) MONTHSDRIPPER JET Nov-Feb Mar-Oct 2-4 3-7 1-2 2-3 Duration (hours) 3-6 2-3MatureTreesIfcoverageisinadequateonmaturetrees,the microirrigationsystemmaynotbeabletomeetthe waterrequirementsofthelargetrees.Runningthe systemforalongertimewillprobablynotmakeup forthelackofcoverage,andthelongerrunningtime willdrivemoreofthewaterbelowthemainroot zone.Hence,designthesystemtocoverasmucharea underthetreeasisaffordable.Inthatway,better growthandyieldscanbeobtained.Table4showsan irrigationscheduleformaturetrees. Table4. Irrigationscheduleformaturetrees FREQUENCY (timesperweek) DRIPPER JET MONTH RIDGE FLAT WOODS RIDGE FLAT WOODS Sep-Feb Mar-Aug 1-2 2-4 2-3 3-5 1-2 2-3 2 3 Duration (hours) 6-10 6-10 4-6 2-4