subsurface drip irrigation (sdi) michael kizer osu extension irrigation specialist biosystems &...

Subsurface Drip IrrigationSubsurface Drip Irrigation(SDI)(SDI)

Michael KizerMichael Kizer

OSU Extension Irrigation SpecialistOSU Extension Irrigation Specialist

Biosystems & Agricultural EngineeringBiosystems & Agricultural Engineering

Subsurface Drip Irrigation Subsurface Drip Irrigation AdvantagesAdvantages

• High water application efficiency

• Uniform water application

• Lower pressure & power requirements

• Adaptable to any field shape

• No dry corners

• Adaptable to automation

Subsurface Drip Irrigation Subsurface Drip Irrigation DisadvantagesDisadvantages

• High initial cost

• Water filtration required

• Complex maintenance requirements– Flushing, Chlorination, Acid injection

• Susceptible to gopher damage

• Salt leaching limitations

Subsurface Drip-Center Pivot ComparisonSubsurface Drip-Center Pivot Comparison(¼-Section Field; ET = 0.25 in/day)(¼-Section Field; ET = 0.25 in/day)

Subsurface DripSubsurface Drip Center PivotCenter Pivot

Area IrrigatedArea Irrigated 160 acres160 acres 125 acres125 acres

Initial CostInitial Cost $900-1100/acre$900-1100/acre $280-360/acre$280-360/acre

Irrigation EfficiencyIrrigation Efficiency 90-95%90-95% 70-85%70-85%

Water RequirementWater Requirement 5.0-5.3 gpm/acre5.0-5.3 gpm/acre 5.5-6.8 gpm/acre5.5-6.8 gpm/acre

Operating PressureOperating Pressure 10-20 psi10-20 psi 25-35 psi25-35 psi

Energy RequirementEnergy Requirement(250-ft lift, ¼ mile supply line)(250-ft lift, ¼ mile supply line)

36 hp-hr/ac-in36 hp-hr/ac-in 48 hp-hr/ac-in48 hp-hr/ac-in

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

Pump Pump StationStation

BackflowBackflowPreventionPrevention

DeviceDevice

FlowmeterFlowmeter

Chemical Chemical Injection Injection SystemSystem

Air & VacuumAir & VacuumRelease ValveRelease Valve

X X

Pressure GagePressure Gage

X X

Flush Valve Flush Valve

XX

Dripline Dripline LateralsLaterals

ZonesZones1 and 1 and

22

SubmainSubmain

FlushlineFlushline

Filtration Filtration SystemSystem

x

X Zone Valve Zone Valve

Diagram courtesy of Kansas State UniversityDiagram courtesy of Kansas State University

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

Netafim TyphoonNetafim Typhoon®® Drip Irrigation Tubing Drip Irrigation Tubing(Clear Demo Tubing)(Clear Demo Tubing)

16-mm diameter, seamless, 13-mil thick extruded PE tubing16-mm diameter, seamless, 13-mil thick extruded PE tubing

Emitter outletEmitter outlet

Netafim TyphoonNetafim Typhoon®® Drip Irrigation Tubing Drip Irrigation Tubing

Flap over emitter outlet:Flap over emitter outlet:- prevents root intrusion- prevents root intrusion- prevents blockage by mineral scale- prevents blockage by mineral scale

T-SystemsT-Systems®® Drip Irrigation Tubing Drip Irrigation Tubing

Emitter OutletEmitter Outlet

Water Inlets to EmitterWater Inlets to Emitter

30 in30 in

60 in60 in

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

12 – 14 in12 – 14 in

Non Wheel- Non Wheel- Track RowTrack Row

Wetting PatternWetting Pattern

Drip TubingDrip Tubing

60-inch dripline spacing is satisfactory on silt loam & clay loam soils60-inch dripline spacing is satisfactory on silt loam & clay loam soils

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

Photo Courtesy of Kansas State UniversityPhoto Courtesy of Kansas State University

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 UniversityPhoto Courtesy of Kansas State University

Plowing in drip tubingPlowing in drip tubing

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

Drip tubing end after being sheared by the trencher

Typical Drip Tubing Connection to SubmainTypical Drip Tubing Connection to SubmainTee in PVC Submain Line Tee in PVC Submain Line w/ 3/4” FPT Openingw/ 3/4” FPT Opening

3/4” FPT - 5/8” PE Barb Adapter3/4” FPT - 5/8” PE Barb Adapter

5/8” PE Supply Tube5/8” PE Supply Tube

5/8” Drip Tubing5/8” Drip Tubing

Stainless Steel Wire Tie

[An identical connection will attach the far end [An identical connection will attach the far end of the drip tubing to the flushing manifold line.]of the drip tubing to the flushing manifold line.]

Typical Drip Tubing Connection to SubmainTypical Drip Tubing Connection to Submain(1 ½ -inch Submains and Larger)(1 ½ -inch Submains and Larger)

Supply Submain or Flushing ManifoldSupply Submain or Flushing Manifold

Neoprene Grommet Inserted Neoprene Grommet Inserted in 21/32” hole in manifoldin 21/32” hole in manifold

Polyethylene Barb Adapter Polyethylene Barb Adapter Inserted in GrommetInserted in Grommet

5/8” Polyethylene 5/8” Polyethylene Supply Tubing Supply Tubing 5/8” Drip 5/8” Drip

Irrigation TubingIrrigation Tubing

Stainless Steel Stainless Steel Wire Twist TieWire Twist Tie

Components for Drip Lateral-Submain ConnectionComponents for Drip Lateral-Submain Connection

21/32” Hole in Submain21/32” Hole in Submain

Neoprene GrommetNeoprene Grommet

Polyethylene Polyethylene Barb AdapterBarb Adapter

5/8” Polyethylene 5/8” Polyethylene Supply Tube Supply Tube (Usually 2-3 ft long)(Usually 2-3 ft long)

Stainless Steel Wire Twist TieStainless Steel Wire Twist Tie

5/8” Drip Irrigation Tubing5/8” Drip Irrigation Tubing

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

Ball Valve for Manual Ball Valve for Manual Flushing of Drip LateralsFlushing of Drip Laterals

Air Vent to Release Air Vent to Release Trapped Air from LateralsTrapped Air from Laterals

Drip Emitter DischargeDrip Emitter Discharge

Q = kHQ = kHxx

where:where:

Q = emitter discharge, gphQ = emitter discharge, gph

k = emitter discharge coefficient, gph/ft of headk = emitter discharge coefficient, gph/ft of head

H = emitter operating head, ftH = emitter operating head, ft

x = emitter discharge exponentx = emitter discharge exponent

(Emitters with x<0.4 are considered pressure compensating, ie (Emitters with x<0.4 are considered pressure compensating, ie

discharge fluctuates less with varying pressure variations.)discharge fluctuates less with varying pressure variations.)

Discharge and Pressure VariationDischarge and Pressure Variation

Pressure Variation Pressure Variation (P(Pminmin/P/Paveave))

Discharge Variation (qDischarge Variation (qminmin / q / qave)ave)

X = 0.2X = 0.2 X = 0.5X = 0.5

95% 99% 97%

90% 98% 95%

85% 97% 92%

80% 96% 89%

75% 94% 87%

70% 93% 84%

Drip Irrigation and Elevation ChangesDrip Irrigation and Elevation Changes

• 2.31 ft of elevation change = 1 psi pressure change2.31 ft of elevation change = 1 psi pressure change

• A 10-ft elevation change (4.3 psi) in a 35-psi A 10-ft elevation change (4.3 psi) in a 35-psi sprinkler system is a 12% pressure variation, sprinkler system is a 12% pressure variation, resulting in a 6% change in sprinkler dischargeresulting in a 6% change in sprinkler discharge

• A 10-foot elevation change in a 10-psi drip system A 10-foot elevation change in a 10-psi drip system is a 43% pressure variation, resulting in a 17% is a 43% pressure variation, resulting in a 17% change in emitter discharge (emitter x=0.44)change in emitter discharge (emitter x=0.44)

2.31 ft = 1 psi

Higher ElevationHigher Elevation

Lower Operating PressureLower Operating Pressure

Less DischargeLess Discharge

Lower Elevation Lower Elevation

Higher Operating PressureHigher Operating Pressure

More DischargeMore Discharge

Elevation Effect on Drip EmitterElevation Effect on Drip EmitterPressure and DischargePressure and Discharge

Pressure compensated emitters are needed on undulating fieldsPressure compensated emitters are needed on undulating fields

Emission UniformityEmission Uniformity

EU = EU = F F [C[Cvv (q (qminmin/q/qaveave)])]

where:where:

EU = Emission Uniformity, (0-100%)EU = Emission Uniformity, (0-100%)

CCvv = Coefficient of manufacturing variation of emitters, (0-1.0) = Coefficient of manufacturing variation of emitters, (0-1.0)

qqminmin = Minimum emitter discharge along the lateral, (gph) = Minimum emitter discharge along the lateral, (gph)

qqaveave = Average emitter discharge along the lateral, (gph) = Average emitter discharge along the lateral, (gph)

EU EU 80% 80% for drip tubing systems in field crops is acceptable. for drip tubing systems in field crops is acceptable.

Coefficient of Variability, CCoefficient of Variability, Cvv

• Cv is a measure of variability in the manufacture of emitters

• In low flow emitters a very small variation in dimensions can have a huge effect of discharge

• The Cv of major manufacturer’s equipment is published (manufacturer’s tests and industry group tests)

Performance of Various Dripline ProductsData from Center for Irrigation Technology (CIT)

Product Product X X C CVV

ChapinChapin (18 gph/100 ft, 12 in) (18 gph/100 ft, 12 in) 0.533 0.037 0.533 0.037

Roberts (15 mil, 24 gph/100 ft, 12 in) Roberts (15 mil, 24 gph/100 ft, 12 in) 0.500 0.032 0.500 0.032

Netafim Typhoon (25 mil, 18 in) Netafim Typhoon (25 mil, 18 in) 0.475 0.0120.475 0.012

Rainbird Rain Tape (8 in) Rainbird Rain Tape (8 in) 0.446 0.0720.446 0.072

Netafim Ram (0.4 gph, hard hose) Netafim Ram (0.4 gph, hard hose) 0.013 0.0300.013 0.030

GAIA (3/8 in ID, porous hose) GAIA (3/8 in ID, porous hose) 1.144 0.4811.144 0.481

Slide Courtesy of Kansas State UniversitySlide Courtesy of Kansas State University

System Emission UniformitySystem Emission Uniformity(Recommended Values from ASAE EP405)(Recommended Values from ASAE EP405)

Emitter Emitter TypeType

Spacing Spacing (ft)(ft)

TopographyTopography Slope Slope (%)(%)

EU Range EU Range (%)(%)

Point Source: Point Source: Perennial cropPerennial crop > 13> 13

UniformUniform < 2< 2 90 to 9590 to 95

Steep/UndulatingSteep/Undulating > 2> 2 85 to 9085 to 90

Point source: Point source: Perennial or Perennial or Semipermanent Semipermanent cropcrop

< 13< 13


Steep/UndulatingSteep/Undulating >2>2 80 to 9080 to 90

Line Source: Line Source: Perennial or Perennial or Annual cropAnnual crop

AllAll


Steep/UndulatingSteep/Undulating > 2> 2 70 to 8570 to 85

Maximum Lateral LengthMaximum Lateral Length

EUxq

HSDL

emitteremitter

inletemitterlateralFmax

LLmaxmax = maximum lateral length, ft = maximum lateral length, ft

DDlaterallateral = lateral line diameter, in = lateral line diameter, in

SSemitteremitter = emitter spacing on lateral, ft = emitter spacing on lateral, ft

HHinletinlet = lateral pressure at inlet from manifold, psi = lateral pressure at inlet from manifold, psi

qqemitteremitter = average emitter flow rate, gph = average emitter flow rate, gph

xxemitteremitter = emitter discharge exponent, unitless = emitter discharge exponent, unitless

EU = required emission uniformity for the lateral, %EU = required emission uniformity for the lateral, %

Maximum Lateral LengthMaximum Lateral Length5/8-in and 7/8-in diameter T-Tape TSX5/8-in and 7/8-in diameter T-Tape TSX

Level Slope : 8 psi Inlet PressureLevel Slope : 8 psi Inlet Pressure

Emitter Emitter SpacingSpacing

Emitter Emitter DischargeDischarge

EU = 90%EU = 90% EU = 85%EU = 85%

D=5/8 inD=5/8 in D=7/8 inD=7/8 in D=5/8 inD=5/8 in D=7/8 inD=7/8 in

24 in24 in

0.34 gph0.34 gph 672 ft672 ft 1203 ft1203 ft 850 ft850 ft 1521 ft1521 ft

0.50 gph0.50 gph 519 ft519 ft 929 ft 929 ft 657 ft657 ft 1175 ft1175 ft

36 in36 in



48 in48 in



System Design Guidelines System Design Guidelines for Uniformityfor Uniformity

• Run lateral lines along contour or slightly downslopeRun lateral lines along contour or slightly downslope• Arrange irrigation zones so that, as nearly as possible,Arrange irrigation zones so that, as nearly as possible,

all emitters in the zone are at same the elevationall emitters in the zone are at same the elevation• Balance flow requirements of all zones if possibleBalance flow requirements of all zones if possible• Use pressure compensating emitters on undulating Use pressure compensating emitters on undulating

lateral runslateral runs• Divide water flow as soon as possible to minimize Divide water flow as soon as possible to minimize

pressure loss and required pipe sizespressure loss and required pipe sizes

FiltrationFiltration

Filtration removes solid contaminants Filtration removes solid contaminants (suspended solids, precipitates, organic (suspended solids, precipitates, organic particles) from the water supplyparticles) from the water supply

• Filtration should be the last treatment process Filtration should be the last treatment process before the water goes to the irrigation systembefore the water goes to the irrigation system

• Match filter system to the irrigation system Match filter system to the irrigation system size, emitter characteristics, and the water size, emitter characteristics, and the water contaminant loadcontaminant load

There are many different types There are many different types of filtration systems. of filtration systems. There are many different types There are many different types of filtration systems. of filtration systems.

The type is dictated by The type is dictated by the water source and the water source and also by emitter size. also by emitter size.

The type is dictated by The type is dictated by the water source and the water source and also by emitter size. also by emitter size.

Filtration Requirements for Drip EmittersFiltration Requirements for Drip Emitters

Filter openings should be Filter openings should be 1/71/7thth – 1/10 – 1/10thth the size of the size of the emitter orificethe emitter orifice

0.020-inch orifice0.020-inch orifice

Sand Media FilterSand Media Filter

For water with heavy For water with heavy load of organic (algae) or load of organic (algae) or inorganic ( silt, clay) inorganic ( silt, clay) contaminants.contaminants.

To back-wash properly, To back-wash properly, the upward flow of water the upward flow of water must be high enough to must be high enough to “float” the top portion of “float” the top portion of the filter sand.the filter sand.

Sand Media Filter SizingSand Media Filter Sizing

Contaminant Contaminant LevelLevel

ConcentrationConcentration

(ppm)(ppm)

Filter Loading RateFilter Loading Rate

(gpm/ft(gpm/ft22))

LightLight 0 – 100 – 10 25 - 3025 - 30

MediumMedium 10 – 10010 – 100 20 – 2520 – 25

HeavyHeavy 100 - 400100 - 400 15 – 2015 – 20

Sand Filter Maximum Flow RateSand Filter Maximum Flow Rate(gpm per tank)(gpm per tank)

Loading Loading RateRate

(gpm/ft(gpm/ft22))

Tank Diameter (inches)Tank Diameter (inches)

1818 2424 3030 3636 4848

1515 2727 4747 7474 106106 189189

2020 3535 6363 9898 141141 251251

2525 4444 7979 123123 177177 314314

3030 5353 9494 147147 212212 377377

Sand Media Types and SizesSand Media Types and Sizes

Sand Sand Media Media

NumberNumber

Effective Effective SizeSize

(mm)(mm)

Uniformity Uniformity CoefficientCoefficient

Media Media TypeType

Filtration Filtration Level Level

(mesh)(mesh)

# 8# 8 1.501.50 1.471.47 Crushed Crushed GraniteGranite

100 - 140100 - 140

# 11# 11 0.780.78 1.541.54 Crushed Crushed GraniteGranite

140 - 200140 - 200

# 16# 16 0.660.66 1.511.51 Crushed Crushed SilicaSilica

140 - 200140 - 200

# 20# 20 0.460.46 1.421.42 Crushed Crushed SilicaSilica

200 - 250200 - 250

Minimum Backwash Flow RateMinimum Backwash Flow Rate(gpm per sand media tank)(gpm per sand media tank)

Media Media TypeType

Tank Diameter (inches)Tank Diameter (inches)

1818 2424 3030 3636 4848

# 8# 8 5151 9191 141141 201201 360360

# 11# 11 2626 4848 7474 105105 188188

# 16# 16 3232 5757 8989 126126 225225

# 20# 20 2626 4848 7474 105105 188188

BackwashingBackwashing

Using two or more small filter units allows the Using two or more small filter units allows the use of filtered water from one or more units to use of filtered water from one or more units to backwash other filter units individually.backwash other filter units individually.

Filtration ModeFiltration Mode Backwashing ModeBackwashing Mode

Grooved Disc FiltersGrooved Disc Filters

For moderately-to-very dirty For moderately-to-very dirty water.water.

A series of grooved, plastic A series of grooved, plastic discs held together by spring discs held together by spring pressure removes particles. pressure removes particles.

Spring pressure on the discs Spring pressure on the discs can be relieved for back-can be relieved for back-washing.washing.

Screen FiltersScreen Filters

For water with light load of inorganic contaminants. For water with light load of inorganic contaminants. A plastic or metal screen removes particles. A plastic or metal screen removes particles.

ChlorinationChlorination

Chlorine is a strong oxidizing agent that Chlorine is a strong oxidizing agent that prevents water contaminants from fouling prevents water contaminants from fouling microirrigation systems.microirrigation systems.

• Biological growths (bacterial slime, algae)Biological growths (bacterial slime, algae)– Growth preventedGrowth prevented

• Dissolved minerals (iron, manganese, etc.)Dissolved minerals (iron, manganese, etc.)– Oxidized so oxides can be filtered outOxidized so oxides can be filtered out

Chlorination ModesChlorination Modes

• ContinuousContinuous

• IntermittentIntermittent

• SuperchlorinationSuperchlorination

Continuous ChlorinationContinuous Chlorination

Used when water treatment is the goalUsed when water treatment is the goal(iron or manganese precipitation)(iron or manganese precipitation)

• Concentration:Concentration: 1 – 2 ppm1 – 2 ppm

• Injection Time:Injection Time: ContinuousContinuous

Intermittent ChlorinationIntermittent Chlorination

Used to prevent or kill biological growthsUsed to prevent or kill biological growths(algae or bacterial slime)(algae or bacterial slime)

• Concentration:Concentration: 10-20 ppm10-20 ppm• Injection Time:Injection Time: 30-60 minutes30-60 minutes• Frequency:Frequency: Depends on severity Depends on severity

of the problem of the problem

SuperchlorinationSuperchlorination

Used to dissolve organic buildup blocking emittersUsed to dissolve organic buildup blocking emitters(algae or bacterial slime)(algae or bacterial slime)

• Concentration:Concentration: 300-500 ppm300-500 ppm• Injection Time:Injection Time: Until all lines are filled;Until all lines are filled;

Shut system down; Shut system down; Leave standing 24 Leave standing 24

hours;hours; Flush system Flush system• Frequency:Frequency: As needed for remediationAs needed for remediation

Chlorine Injection RateChlorine Injection Rate

IR = IR = Q x CQ x C 167 x S 167 x S

where:where:

IR = chlorine injection rate, gphIR = chlorine injection rate, gph

Q = irrigation flow rate, gpmQ = irrigation flow rate, gpm

C = chlorine concentration required, ppmC = chlorine concentration required, ppm

S = strength of chlorine source, %S = strength of chlorine source, %

ExampleExample

An irrigator wants to inject 20 ppm free chlorine An irrigator wants to inject 20 ppm free chlorine into his 500 gpm irrigation system using calcium into his 500 gpm irrigation system using calcium

hypochlorite (65% Clhypochlorite (65% Cl22) as the chlorine source.) as the chlorine source. What is the required injection rate?What is the required injection rate?

IR = IR = Q x CQ x C = = 500 gpm x 20 ppm500 gpm x 20 ppm = = 0.92 gph0.92 gph 167 x S 167 x S 167 x 65% 167 x 65%

Chlorination and pHChlorination and pH

The water pH determines if The water pH determines if free Clfree Cl22 becomes hypochlorite becomes hypochlorite

(OCl (OCl--), or hychlorous), or hychlorous acid (HOCl) which kills acid (HOCl) which kills organisms 40-80 times organisms 40-80 times more effectively. more effectively.

Chlorine SourcesChlorine Sources

• Calcium hypochlorite Calcium hypochlorite (65-70% Cl(65-70% Cl22))

– Granular “swimming pool” chlorineGranular “swimming pool” chlorine– Calcium precipitation problems in hard waterCalcium precipitation problems in hard water

• Sodium hypochlorite Sodium hypochlorite (5-15% Cl(5-15% Cl22))

– Liquid household bleachLiquid household bleach– Preferred source for hard waterPreferred source for hard water

• Chlorine gas Chlorine gas (100% Cl(100% Cl22))

– Poison gasPoison gas– Very large systems & trained technicians onlyVery large systems & trained technicians only

Acid InjectionAcid Injection

• Prevents mineral precipitationPrevents mineral precipitation

• Dissolves scale build-up on emitters Dissolves scale build-up on emitters (Reduce pH to 4.0 for 30-60 minutes)(Reduce pH to 4.0 for 30-60 minutes)

• Can provide fertility Can provide fertility – N-phuric acid (nitrogen)N-phuric acid (nitrogen)– phosphoric acid (phosphorous)phosphoric acid (phosphorous)

Venturi Chemical InjectorVenturi Chemical Injector

Bypass venturi Bypass venturi injection device injection device for injection of for injection of liquid chlorine, liquid chlorine, liquid fertilizer liquid fertilizer or acid.or acid.

Cutaway of a Cutaway of a venturi injector venturi injector cross-section.cross-section.

throttling valvethrottling valve

chemical suction portchemical suction port

Hydraulic Powered Hydraulic Powered Chemical InjectorChemical Injector

drive water inlet & filterdrive water inlet & filter

chemical solution intakechemical solution intake

chemical solution injection portchemical solution injection port

drive water exhaust portdrive water exhaust port

Chemical Injection PumpChemical Injection Pump

positive displacement positive displacement piston pumppiston pump

SDI System MaintenanceSDI System Maintenance

• Lateral flushing scheduleLateral flushing schedule (sediment)(sediment)

• Chlorine injection Chlorine injection scheduleschedule(biological growths)(biological growths)

• Acid injection scheduleAcid injection schedule(chemical precipitates & scaling)(chemical precipitates & scaling)

SDI System LongevitySDI System Longevity

• In 1990 Sundance Farms (Maricopa, AZ) In 1990 Sundance Farms (Maricopa, AZ) was irrigating Pima cotton with a SDI was irrigating Pima cotton with a SDI system (Reed Bi-Wallsystem (Reed Bi-Wall®®) that had been in ) that had been in continuous use for 18 years.continuous use for 18 years.

• Kansas State University currently has Kansas State University currently has SDI research plots that have been using SDI research plots that have been using the same equipment for 13 years.the same equipment for 13 years.

0000 1111 2222 3333 4444 5555 6666 7777 8888 9999 10101010 11111111 12121212 13131313

YearsYearsYearsYears

90909090

95959595

100100100100

105105105105

110110110110

Per

cen

t o

f F

irst

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son

Flo

w R

ate

Per

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t o

f F

irst

Sea

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Flo

w R

ate

Per

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irst

Sea

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Flo

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Per

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irst

Sea

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Flo

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ate K-State SDI Research Site, Colby, KansasK-State SDI Research Site, Colby, KansasK-State SDI Research Site, Colby, KansasK-State SDI Research Site, Colby, Kansas

23 separate zones represented23 separate zones represented23 separate zones represented23 separate zones represented

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

Salt accumulation leached Salt accumulation leached downward by successive water downward by successive water applicationsapplications

Salt accumulation leached Salt accumulation leached radially outward from drip radially outward from drip tubingtubing

Subsurface DripSubsurface Drip Sprinkler/FloodSprinkler/Flood

Salt Accumulation and SDISalt Accumulation and SDI

• Rate of accumulation is slowed because of Rate of accumulation is slowed because of more efficient water applicationmore efficient water application

• Good quality irrigation water (TDS<500 mg/l) Good quality irrigation water (TDS<500 mg/l) and reasonable annual rainfall (16 in.) makes and reasonable annual rainfall (16 in.) makes the problem minimal in OK Panhandlethe problem minimal in OK Panhandle

• If salt has accumulated on soil surface, operate If salt has accumulated on soil surface, operate system during light rains to prevent leaching system during light rains to prevent leaching into irrigated portion of root zoneinto irrigated portion of root zone

PREC Subsurface Drip Irrigation SystemPREC Subsurface Drip Irrigation System

• Funded by USDA-CSREES grantFunded by USDA-CSREES grant

• Primary goal is to evaluate SDI for Primary goal is to evaluate SDI for application of swine lagoon effluentapplication of swine lagoon effluent– Filtration requirementsFiltration requirements– Odor releaseOdor release– Nutrient utilizationNutrient utilization– Salt accumulation in soilSalt accumulation in soil– Long-term performance of systemLong-term performance of system

• Secondary goals to evaluate water use Secondary goals to evaluate water use efficiency of systemefficiency of system

Small research plots during supply line installationSmall research plots during supply line installation

PREC Subsurface Drip Irrigation Plot MapPREC Subsurface Drip Irrigation Plot Map

15 ft15 ft

45 ft45 ft

50 ft50 ft

Small Subsurface Drip Irrigation PlotsSmall Subsurface Drip Irrigation PlotsReplicated Agronomic StudiesReplicated Agronomic Studies

Plot 1: 0.53 gph emitters @ 12 inch spacing onPlot 1: 0.53 gph emitters @ 12 inch spacing on the lateralthe lateral



NNThe sixteen, 3-plot blocks (Plots 1-48) are separated on The sixteen, 3-plot blocks (Plots 1-48) are separated on N-S by 15-ft alleys, and on E-W by 30-ft turn-row area.N-S by 15-ft alleys, and on E-W by 30-ft turn-row area.

60 ft60 ft

240 ft240 ft

600 ft600 ft

Large Subsurface Drip Irrigation PlotsLarge Subsurface Drip Irrigation PlotsField-Scale System Hydraulic StudiesField-Scale System Hydraulic Studies





NN

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

(60-inch tubing spacing)(60-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

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

(30-inch tubing spacing)(30-inch tubing spacing)

12 inches12 inches 18 inches18 inches 24 inches24 inches

0.16 gph0.16 gph 0.0860.086 0.0680.068 0.0520.052

0.21 gph0.21 gph 0.1120.112 0.0900.090 0.0680.068

0.33 gph0.33 gph 0.1760.176 0.1420.142 0.1060.106

0.53 gph0.53 gph 0.2840.284 0.2260.226 0.1700.170

Emitter SpacingEmitter Spacing

Emitter DischargeEmitter Discharge

Go ‘Pokes!Go ‘Pokes!

subsurface drip irrigation (sdi) michael kizer osu extension irrigation specialist biosystems &...

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