Chapter X: Chemigation

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Chapter X Chemigation
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INTRODUCTION

• Chemigation is the application of chemicals
  through the irrigation system.
• The chemigation offers following economic
  advantages compared to other conventional
  methods
• - Provides uniformity in the
  application of chemicals allowing the
  distribution of these in small quatities during
  the growing season when and where
  these are needed.
• - Reduces soil compactation and the
  chemical damage to the crop.

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INTRODUCTION

• - Reduces the quantity of chemicals
  used in the crop and the hazards/ risks during
  the application.
• - Reduces the pollution of the
  environment.
• - Reduces the costs of manual labor,
  equipment and energy.

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CHEMICAL INJECTION METHODS

• Injection by a pressure pump
• Injection by pressure difference
• Injection by Venturi principle
• Injection in the suction line of the irrigation
  pump.

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SELECTION OF A PUMP FOR THE INJECTION OF A
CHEMICAL

• Consider the parts that will be in direct contact
  with the chemical substances.
• These parts must be of stainless steel or a
  corrosion resistant material.

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• 3. The injection method consists of basic
  components such as Pump, pressure regulator, the
  gate valve, the pressure gage, the connecting
  tubes, check valve, and the chemigation tank.

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• Figure 1. Chemical injection method

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• Figure 2. Chemical injection method

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• Venturi type
• Figure 3. Chemical injection method

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• Figure 4. Chemical injection method

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• Figure 5. Chemical injection method

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INJECTION BY VENTURI PRINCIPLE

• A Venturi system can be used to inject chemicals
  into the irrigation line.
• There is a decrease in the pressure accompanied
  by an increase in the liquid velocity through a
  Venturi.
• The pressure difference is created across the
  Venturi and it is sufficient to cause a flow by
  suction of the chemical solutions from a tank.

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INJECTION IN THE SUCTION LINE OF THE IRRIGATION
PUMP

• 1. A hose or tube can be connected to the suction
  pipe of the irrigation pump.
• 2. A second hose or tube is connected to the
  discharge line of a pump to supply water to the
  chemigation tank .

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INJECTION IN THE SUCTION LINE OF THE IRRIGATION
PUMP

• 3. This method should not be used with
  
  
  
  
  toxic
  chemical compounds because of possible
  contamination of the water source.
• 4. A foot valve or safety valve at the end of
  a suction line can avoid the
  contamination.

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FERTIGATION

• All fertilizers for the chemigation purpose must
  be soluble (See table 1).
• The partially soluble chemical compounds can
  cause clogging and thus can create operational
  problems .

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NITROGEN

• Nitrogen is an element that is most frequently
  applied in the drip irrigation system.
• If the irrigation water has high concentration of
  calcium and magnesium bicarbonates, then these
  can result in precipitation of chemical
  compounds. This enhances the clogging problems in
  the drippers, filters and laterals.

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NITROGEN

• 3. The principal sources of nitrogen for
  
  
  chemigation are anhydrous ammonia, liquid
  ammonia, ammonium sulfate, urea, ammonium
  nitrate and calcium nitrate.

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NITROGEN

• 4. The urea is very soluble and it does not react
  with the irrigation water to form ions, unless
  the water contains the enzyme urease.
• 5. Urease enzyme can be present if the water has
  large amounts of algae or other biological
  agents.

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PHOSPHORUS

• The fertigation of phosphorus can enhance
  obstructions in the drip irrigation system.
• The phosphorus moves slowly in the soil and the
  root zone.
• In addition, the moist soil particles absorb
  phosphorus to form insoluble compounds .

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PHOSPHORUS

• 4. The organic phosphates (orthophosphates) and
  urea phosphate are relatively soluble in water
  and can easily move in the soil.
• 5. The organic phosphates do not precipitate, and
  the hydrolysis of an organic phosphate requires
  large lapse time.

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POTASSIUM

• This can be fertigated in the form of a potassium
  sulfate, potassium chloride and potassium
  nitrate.
• Generally, potassium salts have good solubility
  in water and cause little problems of
  precipitation.

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Priming valve
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MICRO NUTRIENTS

• The micro - nutrients are supplied in the form of
  chelates.
• Thus its solubility in the water is increased and
  these do not cause any problems of obstruction
  and precipitation.
• The chelates should be dissolved before
  fertigation.

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MICRO NUTRIENTS

• 4. The chemigation of micro-nutrients benefits
  the plant to accomplish a good development and
  growth.
• 5. In addition, the operational cost is lower
  compared to the foliage application.

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PESTIGATION

• Although sufficient information is available on
  the application of pesticides through the drip
  irrigation system in different regions of the
  world, yet the data does not necessarily adapt to
  the weather and soil conditions of all regions of
  the world.

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INSECTIGATION

• 1. When dispersed emulsions or formulations are
  used in water, these comprise of liquid phase and
  therefore can be distributed uniformly.
• 2. In order to control foliage insects, the
  insecticides applied through the drip irrigation
  system must be systematic and of high solubility.

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FUMIGATION

• The fungi dragged by the wind are difficult to
  control.
• These fungi produce numerous spores that often
  are located on the leaves which are not easy to
  control.
• By means of injection of soluble and systematic
  fungicides through the drip irrigation, the
  effectiveness of certain fungicides can be
  increased.

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NEMAGATION

• The application of fumigants and nematicides
  through the drip irrigation system is convenient
  and safe.
• Using this method, the soil can be fumigated in
  an efficient way to control nematodes and other
  detrimental organisms.
• The success of the operation will depend on many
  conditions such as Temperature, soil moisture,
  soil aeration, content of organic matter, and
  uniformity of irrigation.

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HERBIGATION

• In places where the rainfall is limited, the
  application of herbicides through drip irrigation
  serves to activate the applied herbicides.
• As the drip irrigation system directly takes the
  water with herbicides to the place where the
  weeds are to be controlled, a uniform
  distribution is obtained. There is a significant
  reduction of losses of non-available chemicals as
  a result of the inactivation by rubbish or
  organic matter.
• Thus the irrigation efficiency can be maximized
  and the efficiency of the herbicide application
  can be increased .

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CHLORATION

• The chlorine is the cheapest and effective
  treatment for the control of bacteria, algae and
  the slime in the irrigation water.
• The chlorine can be injected in form of chlorine
  powder (solid) and chlorine gas (See chapter XI).
  
• The gas treatment is the expensive and dangerous
  for the operator .

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CHLORATION

• The calcium hyperchlorite can also be
  used, but the calcium tends to precipitate.
• 5. The chlorine also acts as a biocide to iron
  and sulfur bacteria .

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INSTALLATION, OPERATION, and MAINTENANCE
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INSTALLATION

• All the electrical devices must resist risks due
  to bad weather.
• In addition, all the valves, accessories,
  fittings and pipes must resist the operating
  pressure.
• To be effective, all types of chemigation
  equipments must be suitable, reliable and
  precise.

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INSTALLATION

• 4. The chemical compounds and the concentrations
  of chemicals must be compatible with the
  injection system.
• 5. The materials of the system must be corrosion
  resistant. These should be washed with clean
  water after each fumigation process.

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OPERATION

• Irrigation system is operated until the soil
  saturates to a field capacity.
• Then the chemicals are injected.
• Once the chemigation has finished, water is
  allowed to flow free in the system for a
  sufficient time to remove all the sediments
  (salts) of chemicals from the laterals and
  drippers.

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MAINTENANCE OF THE SYSTEM

• The maintenance is a routine procedure.
• One should inspect all the components of the
  injection system after each application.
• It is recommended to replace the defective
  components before these will stop working
  altogether.

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MAINTENANCE OF THE SYSTEM

• 4. In order to clean the injection system, it
  is convenient to have the water accessible near
  the system.
• 5. After each application, it is recommended
  to clean and wash exterior of all the parts with
  water and detergent, and to rinse with clean
  water.
• The chemigation system can be cleaned in two
  ways
• By pressurized air.
• By using acids or other chemical agents.

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CALIBRATION

• The calibration consists of adjustment of the
  injection equipment to supply a desired amount of
  chemical. The adjustment is necessary to make
  sure that the recommended dosage is applied.
• An excess of chemical is very dangerous and
  hazardous, whereas a small amount will not give
  effective results.
• The use of excess fertilizers is not economical.
  The amounts less than recommended dosages may
  cause reduction in the crop yield.
• The precise calibration helps us to obtain
  accurate, reliable and desirable results.

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CALIBRATION

• 4. The precise calibration helps us to obtain
  accurate, reliable and desirable results.
• 5. A simple calibration consists of the
  collection of a sample of a chemical solution
  that is being injected to cover the desired area
  during the irrigation cycle .

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• 6. During the chemigation process, the rate of
  injection of a chemical compound can be
  calculated with the following equation

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CALIBRATION EQUATION

• g Rate of injection (liters/hour)
• f Quantity of chemical compound (Kg./ hectare)
  
• A Irrigation area (hectares)
• C Concentration of the chemical in the
  solution (Kg./liter)
• t2 Chemigation time (hours)
• tr Irrigation duration (hours)

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SAFETY CONSIDERATIONS

• It is recommended to use specialized equipment to
  protect the water source, the operators of the
  system and to avoid risks, health hazards and
  accidents.
• The operator of the chemigation equipment must
  take all precautions To use protective clothes,
  boots, protective goggles and gloves .

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• SAFETY CONSIDERATIONS
• 3. It is necessary to install a safety valve
  (check valve or one way valve) in the main line
  between the irrigation pump and the injection
  point. A manual gate valve is not enough to
  avoid contamination of the water source. The
  safety valve allows the water flow in a forward
  direction.

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SAFETY CONSIDERATIONS

• 4. If it is properly installed, it avoids back
  flow of chemicals towards the water source.
• 5. It is safe to install an air-relief valve
  (vacuum breaker) between the irrigation pump and
  safety valve. The air-relief valve allows escape
  of air from the system. It will avoid suction of
  chemical solution towards the water source .
• 6. The automatic solenoid valve is interconnected
  electrically to the injection pump. This
  interconnection allows automatic closing of the
  valve in the supply line of chemical. Thus it
  avoids flow of water in both directions when the
  chemigation pump is not in operation .

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SAFETY CONSIDERATIONS

• The top of a chemical tank should be provided
  with wide openings that will allow easy filling
  and cleaning. In addition, the tank must be
  provided with a sieve or a filter. The tank must
  be corrosion resistant such as Stainless steel
  or reinforced plastic with fiber glass.
• The waiting period to enter the field is
  necessary to avoid health hazards and risks. The
  precautions are necessary so that persons or
  animals do not enter the treated area during the
  application of pesticides and toxic substances.

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TROUBLE SHOOTING
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TROUBLE SHOOTING
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TROUBLE SHOOTING
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TROUBLE SHOOTING
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BIBLIOGRAPHY

• Aplique los plaguicidas correctamente Guía para
  usuarios comerciales de plaguicidas, 1967.
  Versión al español. EPA (Agencia de Protección
  Ambiental Federal en cooperación con el Servicio
  Extensión Agrícola Federal).
• BAR-RAM Irrigation Systems Instructions for the
  operation and maintenance. Pages 3-5 .
• 3. Goyal, M.R, J. Román, F. Gallardo Covas,
  L.E. Rivera and R. Otero Dávila, 1983 Chemigation
  via trickle systems in Vegetables and fruit
  orchards. Paper presented at 1983 meeting of the
  American Society of Agricultural Engineers.
  Montana States University, Montana.

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BIBLIOGRAPHY

• 4. Harrison, D. S., 1974. Inyection of liquid
  fertilizer materials into irrigation
• systems. University of Florida,
  Gainesville, Pages. 3-6, 10-11.
• 5. Proceedings of the National Symposium on
  Chemigation. Rural
• Development Center Of University of
  Georgia, Tifton-CA., August 1982.
• 6. Rolston, D. E., R. S. Rauschkolb, C. J.
  Phene, R. J. Miller, K. Uriu, R. M.
• Carlson and D. W. Henderson, 1979.
  Applying nutrients and other
  chemicals to trickle irrigated crops. University
  of California, Pages. 3-12.
• 7. Smajtrla, A. G., D. S. Harrison, J. C. Good
  and W. J. Becker, 1982.
• Chemigation Safety. Agricultural
  Engineering Fact Sheet, Florida
• Cooperative Extension Service, Institute
  of Food and Agricultural Sciences,
• University of Florida.

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ltwww.water-research.netgt
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Check valve
Figure 6. The installation of a check valve (The
nitrogen and pesticides tanks are behind the
check valve)
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Venturi
Figure 7. Bypass Venturi system
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Chlorine metering pump
Pressure gage
Chlorine solution tank
From water reservoir
Booster pump
ltwww.advancedh2o.comgt
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Chemigation by Venturi injection
ltwww.water-research.netgt
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  of life that word is love.
  - Sophocles

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