Chlorine Sources

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Microirrigation Management in Grapes Mike Kizer,
Extension Irrigation Specialist
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Grape Microirrigation Management Issues

• Water Supply Quality Issues
• Chlorination
• Acid Injection
• Filtration
• Irrigation Scheduling
• Water Stress Control
• Regulated Deficit Irrigation

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Irrigation Water Testing Before you go very
far in an irrigation development plan, get an
irrigation water test for 15 from the OSU Soil,
Water Forage Analytical Lab. through your
County Extension Educator
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Microrrigation Water Quality Issues

• Biological Growth Control
• Chlorination
• Mineral Precipitate Control
• Acidization
• Particulate Control
• Filtration

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Chlorination

• Chlorine is a strong oxidizing agent that
  prevents water contaminants from fouling
  microirrigation systems.
• Dissolved minerals (iron, manganese, etc.)
• Biological growths (bacterial slime, algae)

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Continuous Chlorination

• Used when water treatment is the goal (iron or
  manganese precipitation)
• Concentration 1 5 ppm
• Injection Time Continuous

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Iron Manganese Precipitation

• Chlorine injection must occur before the filter
• Mn precipitates much slower than Fe
• (Mn treatment may require chlorinating the well)
• Inject 1 ppm free Cl for each 0.7 ppm Fe
• Fe and Mn are more soluble at lower pH

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Intermittent Chlorination

• Used to prevent or kill biological
  growths (algae or bacterial slime)
• Concentration 10-20 ppm
• Injection Time 30-60 minutes
• Frequency Depends on severity of the
  problem

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Superchlorination

• Used to dissolve organic buildup blocking
  emitters (algae or bacterial slime)
• Concentration 300-500 ppm
• Injection Time Until all lines are
  filled Shut system down Leave standing
  24 hours Flush system
• Frequency As needed for remediation

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Chlorine Sources

• Calcium hypochlorite Ca(OCl)2
• granular swimming pool chlorine bleach
• 45-70 Cl2
• check for precipitation problems
• Sodium hypochlorite NaOCl
• liquid household bleach
• 5.25 Cl2

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Venturi Chemical Injector
throttling valve
Bypass venturi injection device for injection of
liquid chlorine, liquid fertilizer or
acid. Cutaway of a venturi injector
cross-section.
chemical suction port
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Hydraulic Powered Chemical Injector
drive water exhaust port
drive water inlet filter
chemical solution injection port
chemical solution intake
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Chemical Injection Pump
positive displacement piston pump
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Acid Injection

• Acid injection can prevent precipitation of
  dissolved minerals in water
• Acid injection can dissolve mineral scale
  clogging emitter orifices
• Injection rate varies (titrate to determine)
• pH goal
• Concentration of acid
• Buffering capacity of the water

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Acid Injection Options

• N-Phuric acid (liquid urea-sulphuric acid mix)
• Provides nitrogen fertility and sulphur
• 10-0-0-18S, 15-0-0-16S 28-0-0-9S formulations
• Phosphoric acid (H3PO4)
• Provides phosphorous fertility
• Muriatic (Hydrochloric) acid (HCl)
• Can purchase by the gallon from Lowes, etc.

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Acid Injection Cautions

• Hazardous solutions Corrosive Toxic
• Hazardous vapors Ventilate properly
• Eye-wash/Shower requirements by OSHA
• Corrosive to metals (even 316 SS in some cases)
• Use only PVC, PE or Polypropylene fittings (No
  Nylon fittings)

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Filtration

• Filtration removes solid contaminants
  (suspended solids, precipitates, organic
  particles) from the water supply
• Filtration should be the last treatment process
  before the water goes to the irrigation system
  (after acidization, chlorination and fertilizer
  injection)
• Match filter system to the irrigation system
  size, the water contaminant load and the
  filtration requirements of your emitters

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Sand Media Filter
For water with heavy load of organic (algae) or
inorganic ( silt, clay) contaminants. To
back-wash properly, the upward flow of water must
be high enough to float the top portion of the
filter sand.
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Sand Media Filter Sizing
Contaminant Level Susp. Solids Concentration (ppm) Filter Loading Rate (gpm/ft2)
Light 0 10 25 - 30
Medium 10 100 20 25
Heavy 100 - 400 15 20
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Sand Filter Maximum Flow Rate(gpm per tank)
Loading Rate (gpm/ft2) Tank Diameter (inches) Tank Diameter (inches) Tank Diameter (inches) Tank Diameter (inches) Tank Diameter (inches)
Loading Rate (gpm/ft2) 18 24 30 36 48
15 27 47 74 106 189
20 35 63 98 141 251
25 44 79 123 177 314
30 53 94 147 212 377
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Sand Media Types and Sizes
Sand Media Number Effective Size (mm) Uniformity Coefficient Media Type Filtration Level (mesh)
8 1.50 1.47 Crushed Granite 100 - 140
11 0.78 1.54 Crushed Granite 140 - 200
16 0.66 1.51 Crushed Silica 140 - 200
20 0.46 1.42 Crushed Silica 200 - 250
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Backwashing Using two or more small filter units
allows the use of filtered water from one or more
units to backwash other filter units individually.
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Grooved Disc Filters
For moderately dirty water. A series of grooved,
plastic discs held together by spring pressure
removes particles. Spring pressure on the discs
can be relieved for back-washing.
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Disk filter bank with two 2-inch filter units
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Screen Filters
For water with light load of suspended solids, a
plastic or metal screen removes particles.
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Grape Water Requirements

• Weather
• Sunshine, Temperature, Wind, Humidity
• Stage of Growth
• Management Aims
• Prevent Yield Loss Due to Water Deficit
• Regulated Deficit Irrigation (RDI)
• Control Vine Growth
• Improve Cold Hardiness
• Improve Fruit (Wine) Quality
• (Arizona researchers recommend some degree of
  water stress after the onset color change)

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http//agweather.mesonet.org
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Root Zone Water Capacity

• Typical grape feeder root depth
• 30 to 70 inches
• Soil available water holding capacity
• 0.06 to 0.21 inches of water/inch of soil

Example 40 inch root depth x 0.15 in/in AWC
6.0 in of available water in feeder root zone
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Soil Water Holding CapacityEffect of Soil Texture
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Maximum Allowable Deficit

• Depleting soil water in the root zone by more
  than 50 can lead to
• slowed vegetative growth
• reduced fruit yield quality
• Mild-to-moderate water stress after fruit set
  through color change can result in increased
  sugar content

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Example

• Grape effective root depth 3 feet
• Eufala fine sand 0.8 in/ft
• Max. Allowable Deficit 50 depletion
• 3 ft x 0.8 in/ft x 50/100 1.2 in
• Intentionally maintaining a root zone water
  deficit of 0.6-1.2 inch will lead to improved
  sugar content in this soil.

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Regulated Deficit Irrigation

• Allow root zone moisture to be depleted to some
  degree
• Maintain deficit by irrigating to only partially
  replenish
• Australian RDI Examples

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Regulated Deficit
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Regulated Deficit
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Poly tubing w/ on-line emitter suspended from
trellis wire
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Poly tubing w/ on-line emitter on ground
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Drip tape suspended from trellis wire
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Runing lateral lines across the slope with a
slight downhill gradient is ideal
Maintaining uniform water distribution on
undulating terrain will require careful design
and use of pressure compensated emitters
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THE END