Drip irrigation (sometimes called trickle irrigation) works by applying water slowly, directly to the soil. The high efficiency of drip irrigation results from two primary factors.
-The first is that the water soaks into the soil before it can evaporate or run off.
-The second is that the water is only applied where it is needed, (at the plant’s roots) rather than sprayed everywhere.
Suitable crops - Drip irrigation is most suitable for row crops (vegetables, soft fruit), tree and vine crops where one or more emitters can be provided for each plant. Generally only high value crops are considered because of the high capital costs of installing a drip system.
Suitable landscape - Drip irrigation is adaptable to any farmable slope. Normally the crop would be planted along contour lines and the water supply pipes(laterals) would be laid along the contour also. This is done to minimize changes in emitter discharge as a result of land elevation changes.
Suitable soil - Drip irrigation is suitable for most soils. On clay soils water must be applied slowly to avoid surface water ponding and runoff. On sandy soils higher emitter discharge rates will be needed to ensure adequate lateral wetting of the soil.
Suitable irrigation water - The of the main problems with drip irrigation is blockage of the emitters. All emitters have very small waterways ranging from 0.2-2.0 mm in diameter and these can become blocked if the water is not clean. Thus it is essential for irrigation water to be free of sediments.
-Blockage may also occur if the water contains algae, fertilizer deposits and dissolved chemicals which precipitate such as calcium and iron.
-Dripping water to individual plants also means that the method can be very efficient in water use. For this reason it is most suitable when water is scarce.
Drip irrigation system layout
-The pump unit takes water from the source and provides the right pressure for delivery into the pipe system.
-The control head consists of valves to control the discharge and pressure In the entire system. It may also have filters to clear the water.
-Mainlines, submains and laterals supply water from the control head into the fields. They are usually made from PVC or polyethylene hose and should be buried below ground because they easily degrade when exposed to direct solar radiation. Lateral pipes are usually 13-32 mm diameter.
-Emitters or drippers are devices used to control the discharge of water from the lateral to the plants. They are usually spaced more than 1 metre apart with one or more emitters used for a single plant such as a tree. For row crops more closely spaced emitters may be used to wet a strip of soil.
-The pump unit takes water from the source and provides the right pressure for delivery into the pipe system.
-The control head consists of valves to control the discharge and pressure In the entire system. It may also have filters to clear the water.
-Mainlines, submains and laterals supply water from the control head into the fields. They are usually made from PVC or polyethylene hose and should be buried below ground because they easily degrade when exposed to direct solar radiation. Lateral pipes are usually 13-32 mm diameter.
-Emitters or drippers are devices used to control the discharge of water from the lateral to the plants. They are usually spaced more than 1 metre apart with one or more emitters used for a single plant such as a tree. For row crops more closely spaced emitters may be used to wet a strip of soil.
Drip irrigation is not a substitute for other proven methods of irrigation. It is just another way of applying water. It is best suited to areas where water quality is marginal, land is steeply sloping or undulating and of poor quality, where water or labour are expensive,or where high value crops require frequent water applications.
Source: FAO
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