Drip irrigation is an efficient method of using water in agriculture, in which a network of perforated pipes carries water at low pressure (two to twenty litres an hour) to individual plants, providing them with just the amount of water they require. Also known as micro-irrigation, this technique is so effective in conserving water that many water utilities exempt drip-irrigated farmland from restrictions during drought.
Unlike irrigation by sprinkler systems, a well-designed drip irrigation system does not waste excess water. It is estimated that drip irrigation is ninety per cent effective in providing the required amount of water to the crop, while sprinklers are only fifty to seventy per cent effective.
There is another advantage is going for drip irrigation. Since drip irrigation pipes apply water directly to the roots of the plant, the rest of the soil stays relatively dry, inhibiting weed growth. This also reduces the contact of leaves, stems and fruit with water, rendering them more resistant to disease. Drip irrigation systems can also be programmed to release precisely the exact amount of water needed by the crop at different stages of its growth, which could result in a better yield and quality of the harvest.
 Origins and history
1860 – Early experiments with drip irrigation using clay pipes just under the soil surface demonstrated that this mode of irrigation used less water than conventional irrigation methods, yet caused a doubling of crop yields.
1873 -- Nehemiah Clark obtained a US patent for first known drip emitter.
1920 – Farmers and scientists experimented with different types of perforated pipes in a variety of materials, creating entire irrigation system s with them.
Post-World War 2 – Cheap and convenient plastic pipes revolutionize drip irrigation research.
 The Israeli Model
The Israeli pioneering scientist Symgha Blass developed the first drip irrigation system using micro tubes connected to the water mains. He had been inspired by the sight of a tree near a leaking tap that had grown much more vigorously than other trees around it.
Since then, Israel has successfully followed the practice of drip irrigation. Since more than half of Israel is arid or semi-arid zones, this mode of irrigation has changed the face of its agriculture. In the last thirty years, Israel’s agricultural output had increased five times, while the amount of water used for irrigation has remained practically the same.
 Advantages of drip irrigation
The most obvious advantage of drip irrigation is that it helps conserve water by not allowing any to be wasted in evaporation, runoff or percolation. It stretches water reserves, and enables smaller amounts of water to benefit larger tracts of farmland. Also, it makes irrigation more uniform, and so fields need not be over-watered to adequately irrigate the more inaccessible parts. Hence, drip irrigation is especially helpful if water is scarce or expensive.
Odd-shaped and narrow areas are easily irrigated with drip systems.
Since water is dripped directly where the plant can absorb it best, ie its root bulb, pesticides, agricultural chemicals and fertilizers can be efficiently applied through drip irrigation. This could bring down fertilizer costs substantially.
Drip irrigation systems can be automated, even linked to a computer which is programmed to deliver water and nutrients to the plants as and when they require it.
Conversion to drip irrigation may be cheaply and easily done, as the hydraulic design of a sprinkler system can be used for it.
 Disadvantages of drip irrigation
Drip irrigation systems are relatively more expensive than regular irrigation methods. Once set up, they also need regular maintenance to work at optimal efficiency. For instance, the tapes and tubes used in drip irrigation are often prone to leaking or plugging.
Implementing this system is rather tricky. The drip tubing has to be placed exactly right for the irrigation to be effective, or else the plant will not receive the amount of moisture that it needs.
 Ideal conditions for drip irrigation
The crops best suited for drip irrigation are row crops (vegetables, soft fruit), grapes and other vine crops. Generally, this method of irrigation is best for high value crops because of the high capital costs of installing a drip system.
Drip irrigation is adaptable to any arable slope, and is effective on most soils. On clayey soils, the water must be applied with very low pressure to avoid runoff and puddles. On sandy soils, water should be applied with greater pressure to ensure adequate lateral wetting of the soil.
- To see a drip irrigation chart, with cost comparisons with other irrigation systems, see http://www.cseindia.org/dte-supplement/water20031115/drip_irrigation.pdf
- For tips on designing a drip irrigation system, go to http://www.sydneywater.com.au/SavingWater/InYourGarden/WateringSystems/
--Geetanjalikrishna 11:38, 30 August 2007 (EDT)