Chemigation

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Chemigation

• Kerry Harrison
• Irrigation Specialist
• University of Georgia

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Chemigation

• Chemigation is the process of applying pesticides
  and fertilizer through irrigation water
• EPA regulations require that the water source be
  protected from contamination by chemical
  solutions in case of unscheduled system shutdown
• Only products specifically labeled for
  chemigation may be applied in this manner

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Why Use Chemigation?
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• Why Use Chemigation?
• Uniformity of application.
• Prescription application of nutrients.
• MAY reduce nutrient requirements.
• Reduces soil compaction.
• Timeliness of application.
• Chemical incorporation.
• Reduce operator hazards.
• MAY reduce environmental contamination.
• Effective
• Economical

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PROBLEM At what rate must material be injected
into system? Commonly referred to as Injection
Rate
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• Chemigation Calibration Steps
• Determine area irrigated in acres
• Determine amount of material desired per acre
• Determine total amount of material needed (Step 1
  x Step 2)
• Determine time for system to cover area.
• Determine injection rate (Step 3/Step 4)
• Repeat above steps to determine range of
  injection rates.

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• Chemigation Calibration for Drip or Solid Set
  Irrigation
• Determine area irrigated in acres.
• Determine amount of material desired per acre.
• Determine total amount of material needed (Step 1
  x Step 2).
• Determine duration of irrigation (hours).
• Determine absolute minimum injection rate (Step
  3/Step 4).
• Increase this rate slightly to insure that no
  material is left in distribution lines.

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Drip vs sprinkler irrigation

• Many of the same problems exist with both types
  of irrigation
• With drip the problems can be magnified
• This is because the water is applied to a much
  smaller area

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Basic Injection Pumps

• Venturi Pumps
• Diaphragm pumps
• Water powered pumps
• Piston pumps
• Other (rotary/gear etc)

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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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Piston Injection Pump
positive displacement piston
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Diaphram Injection Pump
diaphram
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Basic Safety requirements

• Irrigation line check valve
• Low pressure drain
• Vacuum relief
• Interlocks
• Injection line Check valves
• Resistant Materials

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Materials

• Hoses
• Reinforced Ethyl Vinyl Acetate (EVA)
• Fittings
• Nylon
• Polypropylene
• Tanks
• Poly
• Fiberglass

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Commercial chemigation valve
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