Microirrigation Management Microirrigation Management in Grapesin Grapes

Mike Kizer, Extension Irrigation SpecialistMike Kizer, Extension Irrigation Specialist

Grape Microirrigation Grape Microirrigation Management IssuesManagement Issues

• Water Supply Quality IssuesWater Supply Quality Issues– ChlorinationChlorination– Acid InjectionAcid Injection– FiltrationFiltration

• Irrigation SchedulingIrrigation Scheduling– Regulated Deficit IrrigationRegulated Deficit Irrigation

Microrrigation Water Quality Microrrigation Water Quality IssuesIssues

• Biological Growth ControlBiological Growth Control– ChlorinationChlorination

• Mineral Precipitate ControlMineral Precipitate Control– AcidizationAcidization

• Particulate ControlParticulate Control– FiltrationFiltration

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.

• Dissolved minerals (iron, manganese, etc.)Dissolved minerals (iron, manganese, etc.)

• Biological growths (bacterial slime, algae)Biological growths (bacterial slime, algae)

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 – 5 ppm1 – 5 ppm

• Injection Time:Injection Time: ContinuousContinuous

Iron & Manganese PrecipitationIron & Manganese Precipitation

• Chlorine injection must occur before the filterChlorine injection must occur before the filter

• Mn precipitates much slower than Fe Mn precipitates much slower than Fe – (Mn treatment may require chlorinating the well)(Mn treatment may require chlorinating the well)

• Inject 1 ppm free Cl for each 0.7 ppm FeInject 1 ppm free Cl for each 0.7 ppm Fe

• Fe and Mn are more soluble at lower pHFe and Mn are more soluble at lower pH

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 hours;Leave standing 24 hours;Flush systemFlush system

• Frequency:Frequency: As needed for remediationAs needed for remediation

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: Ca(OCl)Ca(OCl)22

– granular “swimming pool” chlorine bleachgranular “swimming pool” chlorine bleach

– 45-70% Cl45-70% Cl22

• Sodium hypochlorite: Sodium hypochlorite: NaOClNaOCl– liquid household bleachliquid household bleach

– 5.25% Cl5.25% Cl22

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 50 gpm irrigation system using household into his 50 gpm irrigation system using household

bleach (5.25% Clbleach (5.25% Cl22) as the chlorine source.) as the chlorine source. What is What is

the required injection rate?the required injection rate?

IR = IR = Q x CQ x C = = 50 gpm x 20 ppm50 gpm x 20 ppm = = 1.14 gph1.14 gph 167 x S 167 x S 167 x 5.25% 167 x 5.25%

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

Acid InjectionAcid Injection

• Acid injection can prevent precipitation of Acid injection can prevent precipitation of dissolved minerals in waterdissolved minerals in water

• Acid injection can dissolve mineral scale Acid injection can dissolve mineral scale clogging emitter orificesclogging emitter orifices

• Injection rate varies (titrate to determine)Injection rate varies (titrate to determine)– pH goal pH goal – Concentration of acidConcentration of acid– Buffering capacity of the waterBuffering capacity of the water

Acid Injection OptionsAcid Injection Options

• N-Phuric acid (liquid urea-sulphuric acid mix)N-Phuric acid (liquid urea-sulphuric acid mix)– Provides nitrogen fertility and sulphurProvides nitrogen fertility and sulphur– 10-0-0-18S, 15-0-0-16S & 28-0-0-9S formulations10-0-0-18S, 15-0-0-16S & 28-0-0-9S formulations

• Phosphoric acid (HPhosphoric acid (H33POPO44))

– Provides phosphorous fertilityProvides phosphorous fertility

• Muriatic (Hydrochloric) acid (HCl)Muriatic (Hydrochloric) acid (HCl)

Acid Injection CautionsAcid Injection Cautions

• Hazardous solutions – Corrosive & ToxicHazardous solutions – Corrosive & Toxic

• Hazardous vapors – Ventilate properlyHazardous vapors – Ventilate properly

• Eye-wash/Shower requirements by OSHAEye-wash/Shower requirements by OSHA• Corrosive to metals Corrosive to metals (even 316 SS in some cases)(even 316 SS in some cases)

• Use only PVC, PE or Polypropylene fittingsUse only PVC, PE or Polypropylene fittings(No Nylon fittings)(No Nylon fittings)

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 system before the water goes to the irrigation system (after acidization, chlorination and fertilizer injection)(after acidization, chlorination and fertilizer injection)

• Match filter system to the irrigation system Match filter system to the irrigation system size and the water contaminant loadsize and the water contaminant load

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.

Grooved Disc FiltersGrooved Disc Filters

For moderately dirty water.For moderately dirty 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.

Disk filter bank with two 2-inch filter unitsDisk filter bank with two 2-inch filter units

Screen FiltersScreen Filters

For water with light load of suspended solids, a For water with light load of suspended solids, a plastic or metal screen removes particles.plastic or metal screen removes particles.

Grape Water RequirementsGrape Water Requirements

• Weather Weather – Sunshine, Temperature, Wind, Humidity)Sunshine, Temperature, Wind, Humidity)

• Stage of GrowthStage of Growth

• Management AimsManagement Aims– Regulated Deficit Irrigation (RDI)Regulated Deficit Irrigation (RDI)

• Control Vine GrowthControl Vine Growth

• Improve Cold HardinessImprove Cold Hardiness

• Improve Fruit (Wine) QualityImprove Fruit (Wine) Quality– (Arizona researchers recommend “some degree of water (Arizona researchers recommend “some degree of water

stress after the onset color change”)stress after the onset color change”)

http://agweather.mesonet.orghttp://agweather.mesonet.org

Regulated Deficit IrrigationRegulated Deficit Irrigation

-Allow root zone moisture to be depleted to some degreeAllow root zone moisture to be depleted to some degree

-Maintain deficit by irrigating to only partially replenishMaintain deficit by irrigating to only partially replenish

Australian RDI ExamplesAustralian RDI Examples

Regulated DeficitRegulated Deficit

Regulated Deficit

THE ENDTHE END