Drip irrigation

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(Redirected from Subsurface drip irrigation)

Image:Irrigation dripper.jpg Drip irrigation also known as trickle irrigation or microirrigation is an irrigation method that applies water slowly to the roots of plants, by depositing the water either on the soil surface or directly to the root zone, through a network of valves, pipes, tubing, and emitters. The goal is to minimize water usage (see below). Drip irrigation may also use devices called micro-spray heads, which spray water in a small area, instead of emitters. These are generally used on tree and vine crops. Subsurface drip irrigation or SDI uses permanently or temporarily buried dripperline or drip tape. It is becoming more widely used for row crop irrigation especially in areas where water supplies are limited.

1 History
2 Components and Operation
3 See also
4 References
5 External links

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History

Drip irrigation was used in ancient times by filling buried clay pots with water and allowing the water to gradually seep into the soil. Modern drip irrigation began its development in Germany in 1860 when researchers began experimenting with subirrigation using clay pipe to create combination irrigation and drainage systems. In 1913, E.B. House at Colorado State University succeeded in applying water to the root zone of plants without raising the water table. Perforated pipe was introduced in Germany in the 1920s and in 1934, O.E. Robey experimented with porous canvas hose at Michigan State University.

Image:VineyardDrip.JPG

With the advent of modern plastics during and after World War II, major improvements in drip irrigation became possible. Plastic microtubing and various types of emitters began to be used in the greenhouses of Europe and the United States. A new technology of drip irrigation was then introduced in Israel by Simcha Blass and his son Yeshayahu. Instead of releasing water through tiny holes, water was released through larger and longer passageways by using friction to slow water inside a plastic emitter. The first experimental system of this type was established in 1959 in Israel by Blass, where he developed and patented the first practical surface drip irrigation emitter. This method was very successful and subsequently spread to Australia, North America, and South America by the late 1960s. In the United States, in the early 1960s, the first drip tape, called Dew Hose, was developed by Richard Chapin (first system established at 1964). [1]

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Components and Operation

Drip irrigation systems may be manually operated or may be operated by a controller with electric or hydraulic valves.

Most large drip irrigation systems employ some type of filter to prevent clogging of the small emitter flowpath. New technologies are now being offered that minimize clogging. Some residential systems are installed without additional filters since potable water is already filtered at the water treatment plant. Virtually all drip irrigation equipment manufacturers recommend that filters be employed and generally will not honor warranties unless this is done.

Because of the way the water is applied in a drip system, traditional surface applications of timed-release fertilizer are sometimes ineffective, so drip systems often mix liquid fertilizer with the irrigation water. This is called fertigation; fertigation and chemigation (application of pesticides and other chemicals such as chlorine or sulfuric acid) use chemical injection equipment such as diaphragm pumps, piston pumps, or venturis. The chemicals may be added constantly whenever irrigating or at intervals. Fertilizer savings of up to 90% are being reported from recent university field tests using drip as compared to spraying.

If properly designed, installed, and managed, drip irrigation may help achieve water conservation by reducing evaporation and overirrigation since water can be more precisely applied to the plant roots, when compared to other types of irrigation such as flood or sprinkler irrigation. However, there have been a number of poorly designed and/or managed systems that have been expensive, colossal failures. In addition, in regions where water supplies are severely limited, there may be no actual water savings, but rather an increase in production while using the same amount of water as before. In very arid regions or on sandy soils, the trick is to apply the irrigation water as slowly as possible.

Drip irrigation is used by farms, commercial greenhouses, and residential gardeners.

Garden drip irrigation kits are increasingly popular and consist of a timer, hose and drippers.

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References

Irrigation, 5th Edition, Claude H. Pair, editor, published by the Irrigation Association, 1983
Trickle Irrigation for Crop Production, F.S. Nakayama and D.A. Bucks, editors, published by Elsevier, 1986, ISBN 0-444-42615-9
S. Blass, Water in Strife and Action (Hebrew), published by Massada limited, Israel, 1973

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