j microirrigation

8/7/2019 J Microirrigation

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MicroirrigationMicroirrigation


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MicroirrigationMicroirrigation

Delivery of water at low flow rates throughDelivery of water at low flow rates through

various types of water applicators by avarious types of water applicators by a

distribution system located on the soildistribution system located on the soilsurface, beneath the surface, or suspendedsurface, beneath the surface, or suspended

above the groundabove the ground

Water is applied as drops, tiny streams, orWater is applied as drops, tiny streams, or

spray, through emitters, sprayers, or porousspray, through emitters, sprayers, or porous

tubingtubing


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Water Application CharacteristicsWater Application Characteristics

Low ratesLow rates

Over long periods of timeOver long periods of time

At frequent intervalsAt frequent intervals

Near or directly into the root zoneNear or directly into the root zone

At low pressureAt low pressure

Usually maintain relatively high water contentUsually maintain relatively high water content

Used on higher value agricultural/horticulturalUsed on higher value agricultural/horticulturalcrops and in landscapes and nurseriescrops and in landscapes and nurseries


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Schematic of a Typical Microirrigation SystemSchematic of a Typical Microirrigation System


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AdvantagesAdvantages High application efficiencyHigh application efficiency

High yield/qualityHigh yield/quality

Decreased energy requirementsDecreased energy requirements

Reduced salinity hazardReduced salinity hazard

Adaptable for chemigationAdaptable for chemigation Reduced weed growth and diseaseReduced weed growth and disease

problemsproblems

Can be highly automatedCan be highly automated


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DisadvantagesDisadvantages High initial costHigh initial cost

Maintenance requirements (emitterMaintenance requirements (emitter

clogging, etc.)clogging, etc.)

Restricted plant root developmentRestricted plant root development

Salt accumulation near plants (along theSalt accumulation near plants (along the

edges of the wetted zone)edges of the wetted zone)


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Salt Movement Under Irrigation with Saline WaterSalt Movement Under Irrigation with Saline Water

Salt accumulation leachedSalt accumulation leached

downward by successive waterdownward by successive water

applicationsapplications


radially outward from dripradially outward from drip

tubingtubing

Subsurface DripSubsurface Drip Sprinkler/FloodSprinkler/Flood


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Types of SystemsTypes of Systems Surface trickle (drip)Surface trickle (drip)

Water applied through small emitterWater applied through small emitter

openings to the soil surface (normally lessopenings to the soil surface (normally less

than 3 gal/hr per emitter)than 3 gal/hr per emitter)

Most prevalent type of microirrigationMost prevalent type of microirrigation

Can inspect, check wetting patterns, andCan inspect, check wetting patterns, andmeasure emitter dischargesmeasure emitter discharges


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Point Source Emitters in a New OrchardPoint Source Emitters in a New Orchard


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Types of Systems ContdTypes of Systems Contd

SpraySpray

Water applied (spray, jet, fog, mist) to the soilWater applied (spray, jet, fog, mist) to the soil

surface at low pressure (normally less thansurface at low pressure (normally less than

about 1 gal/min per spray applicator)about 1 gal/min per spray applicator)

Aerial distribution of water as opposed to soilAerial distribution of water as opposed to soil

distributiondistribution Reduced filtration and maintenanceReduced filtration and maintenance

requirements because of higher flow raterequirements because of higher flow rate


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Types of Systems ContdTypes of Systems Contd BubblerBubbler

Water applied as a small stream to flood theWater applied as a small stream to flood the

soil surface in localized areas (normally lesssoil surface in localized areas (normally less

than about 1 gal/min per discharge point)than about 1 gal/min per discharge point)

Application rate usually greater than the soil'sApplication rate usually greater than the soil's

infiltration rate (because of small wettedinfiltration rate (because of small wetteddiameter)diameter)

Minimal filtration and maintenanceMinimal filtration and maintenance

requirementsrequirements


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Types of Systems ContdTypes of Systems Contd

Subsurface trickleSubsurface trickle

Water applied through small emitterWater applied through small emitter

openings below the soil surfaceopenings below the soil surface

Basically a surface system that's beenBasically a surface system that's been

buried (few inches to a couple feet)buried (few inches to a couple feet)

Permanent installation that is "out of thePermanent installation that is "out of theway"way"


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30 in30 in

60 in60 in

Typical Subsurface Drip Tubing Installation for Row CropsTypical Subsurface Drip Tubing Installation for Row Crops

1212 14 in14 in

Non WheelNon Wheel--

Track RowTrack Row

Wetting PatternWetting Pattern

Drip TubingDrip Tubing

6060--inch dripline spacing is satisfactory on silt loam & clay loam soilsinch dripline spacing is satisfactory on silt loam & clay loam soils


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System ComponentsSystem Components

PumpPump

Control headControl head

FiltersFilters

Chemical injection equipment (tanks, injectors,Chemical injection equipment (tanks, injectors,backflow prevention, etc.)backflow prevention, etc.)

Flow measurement devicesFlow measurement devices

ValvesValves ControllersControllers

Pressure regulatorsPressure regulators


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System Components, ContdSystem Components, Contd

Mainlines and Submains (manifolds)Mainlines and Submains (manifolds)

Often buried and nearly always plastic (PVC)Often buried and nearly always plastic (PVC)

LateralsLaterals

Plastic (PE)Plastic (PE)

Supply water to emitters (sometimesSupply water to emitters (sometimes

"emitters" are part of the lateral itself)"emitters" are part of the lateral itself)


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Applicator HydraulicsApplicator Hydraulics

GeneralGeneral Need pressure in pipelines to distributeNeed pressure in pipelines to distribute

water through the system, but thewater through the system, but the

applicator needs to dissipate that pressureapplicator needs to dissipate that pressure

qqee = emitter discharge= emitter discharge

K = emitter discharge coefficientK = emitter discharge coefficient

H = pressure head at the emitterH = pressure head at the emitter

X = emitter discharge exponentX = emitter discharge exponent

(varies with emitter type)(varies with emitter type)

xKHeq !


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Characteristics of Various Types of EmittersCharacteristics of Various Types of Emitters


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Emitter HydraulicsEmitter Hydraulics

Emitter TypeEmitter Type

Coefficient, KCoefficient, K -- Exponent, XExponent, X

Emitter Discharge, gpmEmitter Discharge, gpm

Operating PressureOperating Pressure

8 psi8 psi 12 psi12 psi 16 psi16 psi

Porous PipePorous Pipe -- 0.112 1.000.112 1.00 2.072.07 3.13.1 4.144.14

Tortuous Path 0.112 0.65Tortuous Path 0.112 0.65 0.750.75 0.970.97 1.171.17

Vortex/Orifice 0.112 0.42Vortex/Orifice 0.112 0.42 0.380.38 0.450.45 0.510.51

Compensating 0.112 0.20Compensating 0.112 0.20 0.200.20 0.220.22 0.230.23


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Estimating Emitter Exponent & CoefficientEstimating Emitter Exponent & Coefficient

Requires discharges qRequires discharges qe1e1, q, qe2e2 at two pressures hat two pressures h11, h, h22

Emitter ExponentEmitter Exponent

Emitter CoefficientEmitter Coefficient

oror

)/log()/log(

21

21

hhqqxee

!

xh

qK

1

1

!xh

qK

2

2

!


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Emitters (Point Source)Emitters (Point Source) LongLong--pathpath

OrificeOrifice

VortexVortex

Pressure compensating (x < 0.5)Pressure compensating (x < 0.5) FlushingFlushing

LineLine--source tubingsource tubing

PorousPorous--wall tubing (pores of capillary size that oozewall tubing (pores of capillary size that ooze

water)water) SingleSingle--chamber tubing (orifices in the tubing or prechamber tubing (orifices in the tubing or pre--

inserted emitters)inserted emitters)

DoubleDouble--chamber tubing (main and auxiliary passages)chamber tubing (main and auxiliary passages)

Applicator Hydraulics ContdApplicator Hydraulics Contd


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SprayersSprayers Foggers, spitters, misters, etcFoggers, spitters, misters, etc

Relatively uniform application over the wetted areaRelatively uniform application over the wetted area

Lateral hydraulicsLateral hydraulics

Very much like sprinkler hydraulics, but on aVery much like sprinkler hydraulics, but on asmaller scalesmaller scale

Since there is usually a large number of emitters,Since there is usually a large number of emitters,

multiple outlet factor (F)multiple outlet factor (F) }} 0.350.35


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OtherDesign and Management IssuesOtherDesign and Management Issues

CloggingClogging Physical (mineral particles)Physical (mineral particles)

Chemical (precipitation)Chemical (precipitation)

Biological (slimes, algae, etc.)Biological (slimes, algae, etc.) FiltrationFiltration

Settling basinsSettling basins

Sand separators (centrifugal or cycloneSand separators (centrifugal or cycloneseparators)separators)

Media (sand) filtersMedia (sand) filters

Screen filtersScreen filters


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There are many different typesThere are many different types

of filtration systems.of filtration systems.

There are many different typesThere are many different types

of filtration systems.of filtration systems.

The type is dictated byThe type is dictated bythe water source andthe water source and

also by emitter size.also by emitter size.

The type is dictated byThe type is dictated bythe water source andthe water source and

also by emitter size.also by emitter size.


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Filtration Requirements for Drip EmittersFiltration Requirements for Drip Emitters

Filter openings should beFilter openings should be

1/71/7thth 1/101/10thth the size ofthe size of

the emitter orificethe emitter orifice

0.0200.020--inch orificeinch orifice


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Plugging Potential of Irrigation Water for

Microirrigation


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Chemical treatmentChemical treatmentAcid: prevent calcium precipitationAcid: prevent calcium precipitation

ChlorineChlorine control biological activity: algae and bacterial slimecontrol biological activity: algae and bacterial slime

deliberately precipitate irondeliberately precipitate iron

FlushingFlushing

after installation or repairs, and as part of routineafter installation or repairs, and as part of routinemaintenancemaintenance

valves or other openings at the end of all pipes,valves or other openings at the end of all pipes,including lateralsincluding laterals

Application uniformityApplication uniformity manufacturing variationmanufacturing variation

pressure variations in the mainlines and lateralspressure variations in the mainlines and laterals

pressurepressure--discharge relationships of the applicatorsdischarge relationships of the applicators


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Subsurface Drip IrrigationSubsurface Drip Irrigation

AdvantagesAdvantages

High water application efficiency

Uniform water application

Lower pressure & power requirements

Adaptable to any field shape

No dry corners vs. center pivot Adaptable to automation


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Subsurface Drip IrrigationSubsurface Drip Irrigation

DisadvantagesDisadvantages High initial cost

Water filtration required

Complex maintenance requirements

Flushing, Chlorination, Acid injection

Susceptible to gopher damage

Salt leaching limitations


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Subsurface DripSubsurface Drip--Center Pivot ComparisonCenter Pivot Comparison

((--S

ection Field; ET =0.

25 in/day)S

ection Field; ET =0.

25 in/day)

Subsurface DripSubsurface Drip Center PivotCenter Pivot

Area IrrigatedArea Irrigated 160 acres160 acres 125 acres125 acres

Initial CostInitial Cost $800$800--1000 acre1000 acre $280$280--360 acre360 acre

Irrigation EfficiencyIrrigation Efficiency 9090--95%95% 7070--85%85%

Water RequirementWater Requirement 5.05.0--5.3 gpm acre5.3 gpm acre 5.55.5--6.8 gpm acre6.8 gpm acre

Operating PressureOperating Pressure 1010--20 psi20 psi 2525--35 psi35 psi

Energy RequirementEnergy Requirement(250(250--ft lift, mile supply line)ft lift, mile supply line)

36 hp36 hp--hr achr ac--inin 48 hp48 hp--hr achr ac--inin


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Gopher Damage on Subsurface Drip TubingGopher Damage on Subsurface Drip Tubing


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Schematic of Subsurface Drip Irrigation (SDI) SystemSchematic of Subsurface Drip Irrigation (SDI) System

PumpPump

StationStation

BackflowBackflow

PreventionPrevention

DeviceDevice

FlowmeterFlowmeter

ChemicalChemical

InjectionInjection

SystemSystem

Air & VacuumAir & Vacuum

Release ValveRelease Valve

X X

Pressure GagePressure Gage

X X

Flush ValveFlush Valve

XX

DriplineDriplineLateralsLaterals ZonesZones1 and 21 and 2

SubmainSubmain

FlushlineFlushline

FiltrationFiltration

SystemSystem

x

X Zone ValveZone Valve

Diagram courtesy of Kansas State UniversityDiagram courtesy of Kansas State University


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Turbulent flow PVC emitter welded inside tubingTurbulent flow PVC emitter welded inside tubing

Netafim TyphoonNetafim Typhoon Drip Irrigation TubingDrip Irrigation Tubing

(Clear Demo Tubing)(Clear Demo Tubing)

1616--mm diameter, seamless, 13mm diameter, seamless, 13--mil thick extruded PE tubingmil thick extruded PE tubing

Emitter outletEmitter outlet


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Netafim TyphoonNetafim Typhoon Drip Irrigation TubingDrip Irrigation Tubing

Flap over emitter outlet:Flap over emitter outlet:

-- prevents root intrusionprevents root intrusion

-- prevents blockage by mineral scaleprevents blockage by mineral scale


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30 in30 in

60 in60 in

Typical Drip Tubing Installation for Row CropsTypical Drip Tubing Installation for Row Crops

1212 14 in14 in

Non WheelNon Wheel--

Track RowTrack Row

Wetting PatternWetting Pattern

Drip TubingDrip Tubing

6060--inch dripline spacing is satisfactory on silt loam & clay loam soilsinch dripline spacing is satisfactory on silt loam & clay loam soils


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Wetting Pattern of a Subsurface Drip LateralWetting Pattern of a Subsurface Drip Lateral

Photo Courtesy of Kansas State UniversityPhoto Courtesy of Kansas State University


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Wider dripline spacings may not work.Wider dripline spacings may not work.Wider dripline spacings may not work.Wider dripline spacings may not work.

Photo Courtesy of Kansas

State University

Photo Courtesy of Kansas

State University


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SDI

System Maintenance

SDI

System Maintenance

Lateral flushing scheduleLateral flushing schedule

(sediment)(sediment)

Chlorine injectionChlorine injection scheduleschedule

(biological growths)(biological growths)

Acid injection scheduleAcid injection schedule

(chemical precipitates & scaling)(chemical precipitates & scaling)


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Salt Movement Under Irrigation with Saline WaterSalt Movement Under Irrigation with Saline Water


downward by successive waterdownward by successive water

applicationsapplications


radially outward from dripradially outward from drip

tubingtubing

Subsurface DripSubsurface Drip Sprinkler/FloodSprinkler/Flood


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Small research plots during supply line installation

Small research plots during supply line installation


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Plowing in drip tubing

Plowing in drip tubing


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Trenching across the drip tubing ends for PVC manifold installationTrenching across the drip tubing ends for PVC manifold installation


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Drip tubing end after being sheared by the trencher


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Components for Drip LateralComponents for Drip Lateral--Submain ConnectionSubmain Connection

21/32 Hole in Submain21/32 Hole in Submain

NeopreneGrommetNeopreneGrommet

PolyethylenePolyethylene

Barb AdapterBarb Adapter

5/8 Polyethylene5/8 Polyethylene

Supply Tube

Supply Tube(Usually 2(Usually 2--3 ft long)3 ft long)

Stainless Steel Wire Twist TieStainless Steel Wire Twist Tie

5/8 Drip Irrigation Tubing5/8 Drip Irrigation Tubing


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Typical Drip Tubing Connection to SubmainTypical Drip Tubing Connection to Submain(1 (1 --inch Submains and Larger)inch Submains and Larger)

Supply Submain or Flushing ManifoldSupply Submain or Flushing Manifold

NeopreneGrommet InsertedNeopreneGrommet Inserted

in 21/32 hole in manifoldin 21/32 hole in manifold

Polyethylene Barb AdapterPolyethylene Barb Adapter

Inserted in GrommetInserted in Grommet

5/8 Polyethylene5/8 Polyethylene

Supply Tubing

Supply Tubing

5/8 Drip5/8 Drip

Irrigation TubingIrrigation Tubing

Stainless SteelStainless Steel

Wire Twist TieWire Twist Tie

Identical connection on distal end for flushing manifold connectionIdentical connection on distal end for flushing manifold connection


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Flush Risers on Distal End of Research PlotsFlush Risers on Distal End of Research Plots

Ball Valve for ManualBall Valve for Manual

Flushing of Drip LateralsFlushing of Drip Laterals

Air Vent to Release TrappedAir Vent to Release Trapped

Air from LateralsAir from Laterals


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SDI Water Application RatesSDI Water Application Rates(inches/hour)(inches/hour)

(60(60--inch tubing spacing)inch tubing spacing)

12 inches12 inches 18 inches18 inches 24 inches24 inches

0.16 gph0.16 gph 0.0430.043 0.0340.034 0.0260.026

0.21 gph0.21 gph 0.0560.056 0.0450.045 0.0340.034

0.33 gph0.33 gph 0.0880.088 0.0710.071 0.0530.053

0.53 gph0.53 gph 0.1420.142 0.1130.113 0.0850.085

Emitter SpacingEmitter Spacing

Emitter DischargeEmitter Discharge

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