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FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS

Guidelines “On - Farm Water Management For Horticulture Crops”

This Guide was prepared in the framework of the project“Good Agriculture Practices For Sustainable Intensification Of The Small Holder Horticulture Sector In Egypt”

Within the framework of cooperation between “Agriculture Research Center (ARC) - Arab Republic of Egypt”

and “Food and Agriculture Organization (FAO)”

Project : Good Agriculture Practices For Sustainable Intensification Of The Small Holder Horticulture Sector In Egypt

Drip irrigationDrip irrigation, which is also known as trickle irrigation or microirrigation, is an irrigation method that allows a grower to control the application of water and fertilizer by allowing water to drip slowly near the plant roots through a network of valves, pipes, tubing, and emitters Plate (22).

Plate (22): Drip irrigation system

For many crops, switching from a conventional flood/furrow or sprinkler system to drip irrigation can reduce water use by 50 percent or more. Crop yields can increase through improved water and fertilizer management under drip irrigation. Drip irrigation is not applicable to all farms. However, when properly managed, it can reduce labor and production costs while improving productivity. Smallholder growers should evaluate the advantages and disadvantages of drip irrigation to determine the benefits for their farms.

Drip irrigation system is used for irrigated the newly reclaimed lands by application of water in the form of the frequent, slow application of water to the specific root zone area of the plant. Most fruit trees and vegetables respond well to localize irrigation systems.

Advantages of drip irrigation• Less water can be used. Drip irrigation requires less than half of the water for

flood or furrow irrigation and less than three-quarters of the water for sprinkler irrigation.


• Lower pressures are required to operate systems resulting in a reduction in energy for pumping.

• Regulate the flow of water at the site of the plant growth, according to the need of plants in different periods of her life and the provision of fixed ground moisture.

• Water use efficiency is increased because plants can be supplied with water in precise amounts.

• Disease pressure may be less because plant leaves remain dry.

• Drip irrigation lead to none saturate the soil with water therefore, the soil ventilation is good.

• Water is applied directly to the plant root zone. No applications are made between rows or other non-productive areas, resulting in better weed control and significant water savings.

• Field practices such as harvesting can continue during irrigation because areas between rows remain dry.

• Fertilizers can be applied efficiently through the drip system.

• Irrigation can be done under a wide range of field conditions.

• Compared to sprinkler irrigation, soil erosion and nutrient leaching can be reduced.

Disadvantages of drip irrigation• Higher initial investment compared to other irrigation methods.

• Requires regular maintenance and high-quality water. If emitters are clogged or the tape damaged, the tape must be replaced.

• The water application pattern must match the planting pattern. If emitters are not properly spaced, root development maybe restricted and plants may die.

• Drip tubes may be lifted by wind or displaced by animals unless covered with mulch, fastened with wire anchor pins, or lightly covered with soil.

• Drip lines can be easily cut or damaged by other farming operations, such as tilling, transplanting, or manual weeding with a hoe. Damage to drip tape caused by insects, rodents, or birds may create large leaks that also require repair.

• Water filtration is necessary to prevent clogging of the small emitter holes.

• Compared to sprinkler irrigation, water distribution in the soil is restricted.


• Drip-tape disposal causes extra cleanup costs after harvest. Planning is needed for drip-tape disposal, recycling, or reuse.

How much water to apply through the drip Irrigation system?To determine how much water to apply through the drip Irrigation system we can use the following next steps:

1- Determined the dripper rateBefore calculating the ‘Application Rate’, the amount of water you need to apply to your plants, you must know how much water comes out of the drip system.We can use the catch approach methods to determine the dipper rate as the following steps:

Place a large can at the top and the bottom of a row Capture water from the dripper hole (Plate, 23). Pick a dripper that is, at minimum, 5 metres from the mains line. Place a twist tie around the pipe, just below the dripper. Have the ends of the twist tie directed into the can. Run the irrigation for an hour. Measure the water from the cans,

and then calculate the average of the two cans.

Example: Can 1= 3.9 L Can 2= 4.1LDripper rate = (3.9 + 4.1) / 2 = 4 Litres per hour.

2- Calculating the application rate for a dripper system

It is important to know how much water per hour your drip irrigation system is putting out every time you apply irrigation. For drip irrigators, the amount of water you are applying can be calculated using the bed width as follows: Plate (23): Capture water from the

dripper hole.

Application Rate (mm/hr) = Dripper Rate (l/hr) / Dripper spacing (m) x Width of bed (m)

For above example:Dripper rate = 4 L/hrDripper spacing = 0.5 mBed width = 0.5 m


Application rate (mm/hr) = 4 / (0.5 x 0.5) = 16 mm per hour

Maintenance of drip irrigationLike everything else, a bit of preventive maintenance will go a long way with keeping your drip system in working order as following:

1- Periodically check your system for any leaks or ware in the drip tubing.

2- Inspect all drip emitters and verify that each are flowing and not clogged.

3- Clean or replace any components that have become clogged or have stopped flowing water.

4- Check the filter screen each week for the first month for any debris built up. Clean the screen with a soft nylon brush and water. The frequency at which your filter screen needs cleaning will depend upon your water’s quality.

5- Check to see if any drip tubing has been moved and under strain.

6- Check for any nicks or cuts and use couplings to replace and bad sections of tubing.

7- Periodic flushing of the mainline, sub-mainline, and drip tape is an excellent maintenance practice. Adapters are available for the ends of each drip tape to automatically flush lines at the end of each irrigation cycle, or they can be manually opened to allow a few gallons of water to flush from the end. This will prevent any buildup of particles or slime at the end of the drip line.

8- Clogging is the most serious threat to a drip irrigation system and arises from physical, biological, and chemical contaminants. Filtration can remove physical contaminants, and chemical water treatment is often necessary to eliminate or remove biological and chemical contaminants. Tapes buried under plastic mulches are much less apt to become clogged from mineral deposits.

9- Bacteria, algae, and slime in irrigation lines can be removed with chlorine or commercial bacterial control agents injected through the fertilizer injection system. A 2-ppm chlorine daily rinse at the end of the irrigation cycle or a 30 ppm "shock treatment" can be used if slime becomes a problem in the system.


Trouble shooting of drip irrigation system

1- Tape is plugging with organic maters (Plate, 24).Cause: Organic material in water supply.Possible solutions: Filtration, water source treatment, and or chemical injection into the irrigation system.

Plate (24): Plugging tape with organic maters

2- The tape is plugging with soil at or near the outlet of the emitterCause: Soil is sucked into emitter due to vacuum condition within tapePossible solutions: Air vents and or vacuum relief valves (Plate, 25).

Plate (25): Air vents and or vacuum relief valves

3- Tape is plugging with non organics (Plate, 26).Cause: Non organic material in water supply that is not removed by filters.Possible solutions: Both primary and secondary filtration (ex: sand media and screen filter). Possible setting basins for fine sediment.


Plate (26): Plugging tape with non organics

4- Tape is plugging with roots growing into the emitter (Plate, 27).Cause: Water-starved roots grow into emitters in search of water.Possible solutions: Soil moisture monitoring, above ground tape application.

Plate (27): Plugging tape with roots growing into the emitter

5- Tape is plugging with chemical precipitatesCause: Reaction between chemicals, fertilizers and water source.Possible solutions:- Chemically treat water, check compatibility of fertilizer with water source.- Consult water quality expert.

6- Tape is leaking from a number of holes shortly after installation (Plate, 28).Cause: Damage on installationPossible solutions: New or


repaired tape installation equipment.

Plate (28): Leaking tape from a number of holes shortly after installation

7- Tape is leaking from a number of random locations, often concentrated at the tape edge (Plate, 29).Cause: Bites from insects, rodents or other pestsPossible solutions: Treat area and or inject irrigation system with approved pesticides

Plate (29): leaking tape from a number of random locations, often concentrated at the tape edge.

8- Tape under clear plastic mulch has random holes that appear to be melted or burned (Plate, 30).


Cause: Water droplets on clear plastic become magnifying lenses that focus sun’s light and burn tape.Possible solutions: Bury the tape slightly or white wash the plastic mulch to avoid solar burning.

Plate (30): Tape under clear plastic mulch has random holes that appear to be melted or burned

9- Tape is bursting and or splitting (Plate, 31).Cause: Pressure is set to high or hydraulic valve pressure spikes before it begins regulating.Possible solutions: Check the operating pressure. If using hydraulic control valves, check for pressure spikes at system start up.

Plate (31): Tape is bursting and or splitting


10- Drippers have calcium deposits or white color buildup (Plate, 32).Cause: Hard water was used.Possible solutions: Remove the dripper from the line and soak for one hour in a chlorine solution.

Plate (32): Drippers have calcium deposits or white color buildup

General Guidelines for Drip Irrigation1- Test the water quality of source water regularly, during the seasonal changes

and/or whenever the water source changes.

2- Keep the bypass valve “open” before switching on the pump and adjust / close the same gradually to adjust the required pressure on the mainline.

3- Always install suitable pump as per design/system requirements.

4- Always maintain the required operating pressure within the system.

5- Do not under or over irrigate. Always maintain optimum moisture level in the field.

6- Carry out the chemical treatment (Acid and/or chlorine treatment) as per requirement to prevent dripper clogging.

7- Keep the lid of filter and fertilizer tank optimally tightened while in operation.

8- Checking filters daily and cleaning if necessary. A clogged screen filter can be cleaned with a stiff bristle brush or by soaking in water.

9- Backwashing sand filters to remove particulates and organic contaminants that block drippers. This should be done at least three times during the season.


10-Checking drip lines for leakage. A large, wet area in the field indicates a leaking drip line. Leaking lines can be repaired by splicing with an inline connector or bypassed with a short piece of feeder tube.

11-Using water treatment chemicals to dissolve excessive mineral deposits and remove buildup of organic contaminants in water supply lines.

Factors that determine which irrigation system is right for the growerThe irrigation systems are varying greatly in costs and have different operation and site requirements. Many factors (water supply, water quality, soil type, field shape and topography, labor, suitability, personal preference) determine which system is right for the grower.

Water Supply: The amount of water available and the cost of the water (due to pumping or direct purchase) will determine the amount of land that can be irrigated and often the type of system you should use.

Water Quality: water high in salts may cause foliar damage if sprayed directly on the plants. In these cases consider systems that deliver water directly on or below the surface such as drip systems.

Soil Type: Light sandy soils are not well suited to furrow or surface irrigation systems. These soils are best irrigated by sprinkler or drip irrigation systems.

Field Shape and Topography:


Odd shaped field not easily irrigated with certain types of sprinkler systems such as center pivots. Rolling topography prohibits the use of furrow or surface systems because water cannot run up hill.

Labor: Labor availability and costs are prime considerations. The labor and skill required for operation and maintenance varies greatly between systems. For example, studies have shown that about one-man-hour per acre is required for a hand-move sprinkler system. Mechanical move systems require 1/10 to ½ as much labor.

Suitability: Choose a system that is compatible with your farming operations, equipment, field conditions and crops and/or crop rotation plan.

Personal Preference: grower can be chosen the irrigation system that is compatible with their farming operations system. If you do not like your system, chances are you will not operate or maintain it properly.

GAP recommendations

1- Drip irrigation, known as trickle irrigation that allows a grower to control the application of water and fertilizer by allowing water to drip slowly near the plant roots.

2- Drip irrigation can reduce water use by 50 percent or more; reduce labor and production costs and increased crop through improved water and fertilizer management.

3- Drip irrigation lead to increase water use efficiency because plants can be supplied with water in precise amounts.

4- Clogging is the most serious threat to a drip irrigation system and arises from physical, biological, and chemical contaminants.

5- Periodic flushing of the mainline, sub-mainline, and drip tape is an excellent


maintenance practice for drip irrigation.

6- Check the filter screen each week for the first month for any debris built up. Clean the screen with a soft nylon brush and water.

7- Back washing sand filters to remove particulates and organic contaminants that block drippers. This should be done at least three times during the season.

8- Filtration can remove physical contaminants, and chemical water treatment is often necessary to eliminate or remove biological and chemical contaminants.

9- A 2-ppm chlorine daily rinse at the end to avoid bacteria, algae clogged or a 30 ppm can be used if slime becomes a problem in the system.

10-Many factors (water supply, water quality, soil type, field shape and topography, labor, suitability, personal preference) determine which system is right for the grower.


Documents

kenanaonline.comkenanaonline.com/files/0079/79898/Drip Irrigation.docx · Web viewDrip tubes may be lifted by wind or displaced by animals unless covered with mulch, fastened with