Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Irrigation shopping experience:

1. Compare - without doubt the biggest advantage that the Irrigation offers shoppers today is the ability to compare thousands of Irrigation at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.

2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about

3. Testimonials - don't know anybody that has bought a Irrigation? Wrong! If the Irrigation is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.

4. Questions - Got a question about Irrigation then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....

5. Reputation - Never heard of the company selling Irrigation? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Irrigation and build up a picture of their reputation for sales, returns, customer service, delivery etc.

6. Returns - still worried that even after all of the above your Irrigation wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.

7. Feedback - happy with your Irrigation then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.

8. Security - check for the yellow padlock on the Irrigation site before you buy, and the s after http:/ /i.e. https:// = a secure site

9. Contact - got a question about Irrigation, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.

10. Payment - ready to pay for your Irrigation, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.



Irrigation is the artificial application of water to the soil usually for assisting in growing crops. In crop production it is mainly used to replace missing rainfall in periods of drought, but also to protect plants against frost.{{Citation| last1 = Snyder | first1 = R. L. | last2 = Melo-Abreu | first2 = J. P. | title = Frost protection: fundamentals, practice, and economics – Volume 1 | booktitle = Environment and Natural Resources Series 10 | publisher = Food and Agriculture Organization of the United Nations | year = 2005 | url = ftp://ftp.fao.org/docrep/fao/008/y7223e/y7223e00.pdf | id = ISSN: 1684-8241. --> Additionally irrigation helps to suppress weed growing in rice fields.{{cite web| last = Williams | first = J. F. | coauthors = S. R. Roberts, J. E. Hill, S. C. Scardaci, and G. Tibbits | title = Managing Water for Weed Control in Rice | publisher = [UC Davis, Department of Plant Sciences | url = http://www.plantsciences.ucdavis.edu/uccerice/WATER/water.htm | accessdate = 2007-03-14 --> In contrast, agriculture that relies only on direct rainfall is sometimes referred to as dryland farming or as rain fed farming. It is often studied together with drainage, which is the natural or artificial removal of surface and sub-surface water from a given area.

Irrigation is also a term used in the Medical/Dental fields and refers to flushing and washing out anything with water or another liquid.

()

History of irrigation . Artistic impression on the banks of Dal Lake, Kashmir, India. tunnel at Turpan, China.Archaeological investigation has identified evidence of irrigation in Mesopotamia and Egypt as far back as the 6th millennium BCE, where barley was grown in areas where the natural rainfall was insufficient to support such a crop.{{cite book| fast = | lirst = | authorlink = | coauthors = | title =The History of Technology – Irrigation | publisher =Encyclopædia Britannica, 1994 edition | date = | location = | pages = | url = | doi = | id = -->

In the Zana Valley of the Andes Mountains in Peru, archaeologists found remains of three irrigation canals Radiocarbon dating from the 4th millennium BCE, the 3rd millennium BCE and the 9th century Common era. These canals are the earliest record of irrigation in the New World. Traces of a canal possibly dating from the 5th millennium BCE were found under the 4th millennium canal. (Tom Dillehay, et al., 2005)

The Indus Valley Civilization in Pakistan and North India (from circa 2600 BCE) also had an early canal irrigation system.{{cite web| last = | first = | authorlink = | coauthors = | title =Ancient India Indus Valley Civilization | work = | publisher =Minnesota State University "e-museum" | date = | url =http://www.mnsu.edu/emuseum/prehistory/india/indus/elements.html | format = | doi = | accessdate = 2007-01-10 --> Large scale agriculture was practiced and an extensive network of canals was used for the purpose of irrigation. Sophisticated irrigation and storage systems were developed, including the reservoirs built at [Girnar in [3000 BCE.Rodda, J. C. and Ubertini, Lucio (2004). ''The Basis of Civilization - Water Science?'' pg 161. International Association of Hydrological Sciences (International Association of Hydrological Sciences Press 2004).

There is evidence of the ancient Egyptian pharaoh Amenemhet III in the Twelfth dynasty of Egypt (about 1800 Common era) using the natural lake of the Faiyum Oasis as a reservoir to store surpluses of water for use during the dry seasons, as the lake swelled annually as caused by the annual flooding of the Nile.{{cite web| last = | first = | authorlink = | coauthors = | title =Amenemhet III | work = | publisher =Britannica Concise | date = | url =http://concise.britannica.com/ebc/article-9006076/Amenemhet-III | format = | doi = | accessdate = 2007-01-10 -->

The Qanats, developed in ancient Persia in about 800 BCE, are among the oldest known irrigation methods still in use today. They are now found in Asia, the middle east and north Africa. The system comprises a network of vertical wells and gently sloping tunnels driven into the sides of cliffs and steep hills to tap groundwater.{{cite web| last = | first = | authorlink = | coauthors = | title =Qanat Irrigation Systems and Homegardens (Iran) | work =Globally Important Agriculture Heritage Systems | publisher =UN Food and Agriculture Organization | date = | url =http://www.fao.org/sd/giahs/other_iran1_desc.asp | format = | doi = | accessdate = 2007-01-10 --> The [noria, a water wheel with clay pots around the rim powered by the flow of the stream (or by animals where the water source was still), was first brought into use at about this time, by [Roman Republic settlers in North Africa. By 150 BCE the pots were fitted with valves to allow smoother filling as they were forced into the water.''Encyclopædia Britannica'', 1911 and 1989 editions

The irrigation works of ancient Sri Lanka, the earliest dating from about 300 BCE, in the reign of King Pandukabhaya and under continuous development for the next thousand years, were one of the most complex irrigation systems of the ancient world. In addition to underground canals, the Sinhalese people were the first to build completely artificial reservoirs to store water. The system was extensively restored and further extended during the reign of King Parakrama Bahu (1153 – 1186 Common era).{{cite web| last =de Silva | first =Sena | authorlink = | coauthors = | title =Reservoirs of Sri Lanka and their fisheries | work = | publisher =UN Food and Agriculture Organization | date =1998 | url =http://www.fao.org/docrep/003/T0028E/T0028E03.htm | format = | doi = | accessdate = 2007-01-10 -->

The oldest known hydraulic engineers of China were Sunshu Ao (6th century BCE) of the Spring and Autumn Period and Ximen Bao (5th century BCE) of the Warring States period, both of whom worked on large irrigation projects. In the Szechwan region belonging to the Qin (state) of ancient China, the Dujiangyan Irrigation System was built in 256 BCE to irrigate an enormous area of farmland that today still supplies water.{{cite book| last = | first = | authorlink = | coauthors = | title =China – history | publisher =Encyclopædia Britannica,1994 edition | date = | location = | pages = | url = | doi = | id = --> By the 1st century AD, during the [Han Dynasty, the Chinese also used [chain pumps that lifted water from lower elevation to higher elevation.Needham, Joseph (1986). ''Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 2, Mechanical Engineering''. Taipei: Caves Books Ltd. Pages 344-346. These were powered by manual foot pedal, hydraulic [waterwheels, or rotating mechanical wheels pulled by [oxen.Needham, Volume 4, Part 2, 340-343. The water was used for [public works of providing water for urban residential quarters and palace gardens, but mostly for irrigation of [farmland canals and channels in the fields.Needham, Volume 4, Part 2, 33, 110.

In fifteenth century Korea the world's first water gauge, woo ryang gyae (Korean language:Hangul), was discovered in 1441 CE. The inventor was Jang Young Sil, a Korean engineer of the Choson Dynasty, under the active direction of the King, Se Jong. It was installed in irrigation tanks as part of a nationwide system to measure and collect rainfall for agricultural applications. With this instrument, planners and farmers could make better use of the information gathered in the survey.{{cite book| last =Baek Sauk Gi | first = | authorlink = | coauthors = | title =Jang Young Sil | publisher =Woong-Jin-Wee-In-Jun-Gi: "Woongjin Publishing Co., Ltd" | date =1987 | location = | pages = | url = | doi = | id = -->

By the middle of the 20th century, the advent of diesel and electric motors led for the first time to systems that could pump groundwater out of major aquifers faster than it was recharged. This can lead to permanent loss of aquifer capacity, decreased water quality, ground subsidence, and other problems. The future of food production in such areas as theNorth China Plain, the Punjab region, and the Great Plains of the US is threatened.

Present extent of irrigation At the global scale 2,788,000 sq km (689 million acres) of agricultural land was equipped with irrigation infrastructure around the year 2000. About 68 % of the area equipped for irrigation is located in Asia, 17 % in America, 9 % in Europe, 5 % in Africa and 1 % in Oceania. The largest contiguous areas of high irrigation density are found in North India and Pakistan along the rivers Ganges and Indus, in the Hai He, Huang He and Yangtze basins in China, along the Nile river in Egypt and Sudan, in the Mississippi-Missouri river basin and in parts of California. Smaller irrigation areas are spread across almost all populated parts of the world.{{cite conference| last = Siebert | first = S. | coauthors = J. Hoogeveen, P. Döll, J-M. Faurès, S. Feick, and K. Frenken | title = The Digital Global Map of Irrigation Areas – Development and Validation of Map Version 4 | booktitle = Tropentag 2006 – Conference on International Agricultural Research for Development | place = Bonn, Germany | date = [2006-11-10 | url = http://www.tropentag.de/2006/abstracts/full/211.pdf | accessdate = 2007-03-14 -->

Types of irrigation Various types of irrigation techniques differ in how the water obtained from the source is distributed within the field. In general, the goal is to supply the entire field uniformly with water, so that each plant has the amount of water it needs, neither too much nor too little.

Surface irrigation In surface irrigation systems water moves over and across the land by simple gravity flow in order to wet it and to infiltrate into the soil. Surface irrigation can be subdivided into furrow, borderstrip or basin irrigation. It is often called flood irrigation when the irrigation results in flooding or near flooding of the cultivated land. Historically, this has been the most common method of irrigating agricultural land.

Where water levels from the irrigation source permit, the levels are controlled by dikes, usually plugged by soil. This is often seen in terraced rice fields (rice paddies), where the method is used to flood or control the level of water in each distinct field. In some cases, the water is pumped, or lifted by human or animal power to the level of the land.

Localized irrigation Localized irrigation is a system where water is distributed under low pressure through a piped network, in a pre-determined pattern, and applied as a small discharge to each plant or adjacent to it. Drip irrigation, spray or micro-sprinkler irrigation and bubbler irrigation belong to this category of irrigation methods.{{Citation| last1 = Frenken | first1 = K. | title = Irrigation in Africa in figures – AQUASTAT Survey – 2005 | booktitle = Water Report 29 | publisher = Food and Agriculture Organization of the United Nations | date = 2005 | url = ftp://ftp.fao.org/agl/aglw/docs/wr29_eng.pdf | id = ISBN 92-5-105414-2 | accessdate = 2007-03-14 -->

Drip, or trickle irrigation See main article at drip irrigation. Water is delivered at or near the root zone of plants, drop by drop. This type of system can be the most water-efficient method of irrigation, if managed properly, since evaporation and runoff are minimized. In modern agriculture, drip irrigation is often combined with plastic mulch, further reducing evaporation, and is also the means of delivery of fertilizer. The process is known as fertigation.Deep percolation, where water moves below the root zone, can occur if a drip system is operated for too long of a duration or if the delivery rate is too high. Drip irrigation methods range from very high-tech and computerized to low-tech and relatively labor-intensive. Lower water pressures are usually needed than for most other types of systems, with the exception of low energy center pivot systems and surface irrigation systems, and the system can be designed for uniformity throughout a field or for precise water delivery to individual plants in a landscape containing a mix of plant species. Although it is difficult to regulate pressure on steep slopes, pressure compensating emitters are available, so the field does not have to be level. High-tech solutions involve precisely calibrated emitters located along lines of tubing that extend from a computerized set of valves. Both pressure regulation and filtration to remove particles are important. The tubes are usually black (or buried under soil or mulch) to prevent the growth of algae and to protect the polyethylene from degradation due to ultraviolet light. But drip irrigation can also be as low-tech as a porous clay vessel sunk into the soil and occasionally filled from a hose or bucket. Subsurface drip irrigation has been used successfully on lawns, but it is more expensive than a more traditional sprinkler system. Surface drip systems are not cost-effective (or aesthetically pleasing) for lawns and golf courses. Netafim,Jain irrigation, Chapin Watermatics, Eurodrip, Plastro Irrigation Systems are major manufacturer of Drip Irrigation Systems. In the past one of the main disadvantages of the subsurface drip irrigation (SDI) systems, when used for turf, was the fact of having to install the plastic lines very close to each other in the ground, therefore disrupting the turfgrass area. Recent technology developments on drip installers like the drip installer at New Mexico State University Arrow Head Center, places the line underground and covers the slit leaving no soil exposed.

Sprinkler irrigation in Plainville, New York, UKIn sprinkler or overhead irrigation, water is piped to one or more central locations within the field and distributed by overhead high-pressure sprinklers or guns. A system utilizing sprinklers, sprays, or guns mounted overhead on permanently installed risers is often referred to as a solid-set irrigation system. Higher pressure sprinklers that rotate are called rotors and are driven by a ball drive, gear drive, or impact mechanism. Rotors can be designed to rotate in a full or partial circle. Guns are similar to rotors, except that they generally operate at very high pressures of 40 to 130 lbf/in² (275 to 900 kPa) and flows of 50 to 1200 US gal/min (3 to 76 L/s), usually with nozzle diameters in the range of 0.5 to 1.9 inches (10 to 50 mm). Guns are used not only for irrigation, but also for industrial applications such as dust suppression and logging.

Sprinklers may also be mounted on moving platforms connected to the water source by a hose. Automatically moving wheeled systems known as traveling sprinklers may irrigate areas such as small farms, sports fields, parks, pastures, and cemeteries unattended. Most of these utilize a length of polyethylene tubing wound on a steel drum. As the tubing is wound on the drum powered by the irrigation water or a small gas engine, the sprinkler is pulled across the field. When the sprinkler arrives back at the reel the system shuts off. This type of system is known to most people as a "waterreel" traveling irrigation sprinkler and they are used extensively for dust suppression, irrigation, and land application of waste water.Other travelers use a flat rubber hose that is dragged along behind while the sprinkler platform is pulled by a cable. These cable-type travelers are definitely old technology and their use is limited in today's modern irrigation projects.

Center pivot irrigation Center pivot irrigation is a form of sprinkler irrigation consisting of several segments of pipe (usually galvanized steel or aluminum) joined together and supported by trusses, mounted on wheeled towers with sprinklers positioned along its length. The system moves in a circular pattern and is fed with water from the pivot point at the center of the arc. These systems are common in parts of the United States where terrain is flat.Most center pivot systems now have drops hanging from a u-shaped pipe called a gooseneck attached at the top of the pipe with sprinkler heads that are positioned a few feet (at most) above the crop, thus limiting evaporative losses. Drops can also be used with drag hoses or bubbler's that deposit the water directly on the ground between crops. The crops are planted in a circle to conform to the center pivot. This type of system is known as LEPA (Low Energy Precision Application). Originally, most center pivots were water powered. These were replaced by hydraulic systems (T-L Irrigation) and electric motor driven systems (Lindsay, Reinke, Valley, Zimmatic). Most systems today are driven by an electric motor mounted low on each span. This drives a reduction gearbox and transverse driveshafts transmit power to another reduction gearbox mounted behind each wheel. Precision controls, some with GPS location and remote computer monitoring, are now available.



Lateral move (side roll, wheel line) irrigation A series of pipes, each with a wheel of about 1.5 m diameter permanently affixed to its midpoint and sprinklers along its length, are coupled together at one edge of a field. Water is supplied at one end using a large hose. After sufficient water has been applied, the hose is removed and the remaining assembly rotated either by hand or with a purpose-built mechanism, so that the sprinklers move 10 m across the field. The hose is reconnected. The process is repeated until the opposite edge of the field is reached.This system is less expensive to install than a center pivot, but much more labor intensive to operate, and it is limited in the amount of water it can carry. Most systems utilize 4 or 5 inch diameter aluminum pipe. One feature of a lateral move system is that it consists of sections that can be easily disconnected. They are most often used for small or oddly-shaped fields, such as those found in hilly or mountainous regions, or in regions where labor is inexpensive.

Sub-irrigation Sub-irrigation also sometimes called seepage irrigation has been used for many years in field crops in areas with high water tables. It is a method of artificially raising the water table to allow the soil to be wikt:moistened from below the plants' root zone. Often those systems are located on permanent grasslands in lowlands or river valleys and combined with drainage infrastructure. A system of pumping stations, canals, weirs and gates allows it to increase or decrease the water level in a network of ditches and the control the water table thereby.

Sub-irrigation is also used in commerce greenhouse production, usually for potted plants. Water is delivered from below, absorbed upwards, and the excess collected for recycling. Typically, a solution of water and nutrients floods a container or flows through a trough for a short period of time, 10-20 minutes, and is then pumped back into a holding tank for reuse. Sub-irrigation in greenhouses requires fairly sophisticated, expensive equipment and management. Advantages are water and nutrient conservation, and labor-saving through lowered system maintenance and automation. It is similar in principle and action to subsurface drip irrigation.

Manual irrigation using buckets or watering cans These systems have low requirements for infrastructure and technical equipment but need high labor inputs. Irrigation using watering cans is to be found for example in peri-urban agriculture around large cities in some African countries.

Sources of irrigation water Sources of irrigation water can be groundwater extracted from springs or by using wells, surface water withdrawn from rivers, lakes or reservoirs or non-conventional sources like treated wastewater, desalinated water or drainage water. A special form of irrigation using surface water is spate irrigation, also called floodwater harvesting. In case of a flood (spate) water is diverted to normally dry river beds (wadi’s) using a network of dams, gates and channels and spread over large areas. The moisture stored in the soil will be used thereafter to grow crops. Spate irrigation areas are in particular located in semi-arid or arid, mountainous regions. While floodwater harvesting belongs to the accepted irrigation methods, rainwater harvesting is usually not considered as a form of irrigation. Rainwater harvesting is the collection of runoff water from roofs or unused land and the concentration of this water on cultivated land. Therefore this method is considered as a water concentration method.

How an in-ground irrigation system works Most commercial and residential irrigation systems are "in ground" systems, which means that everything is wikt:buried in the ground. With the pipes, sprinklers, and irrigation valves being hidden, it makes for a cleaner, more presentable landscape without garden hose (tubing)s or other items having to be moved around manually.

Water source and piping The beginning of a sprinkler system is the water source. This is usually a tap into an existing (city) water line or a pump that pulls water out of a well or a pond. The water travels through pipes from the water source through the valves to the sprinklers. The pipes from the water source up to the irrigation valves are called "mainlines", and the lines from the valves to the sprinklers are called "lateral lines". Most piping used in irrigation systems today are HDPE and MDPE or Polyvinyl chloride or PEX plastic pressure pipes due to their ease of installation and resistance to corrosion. After the water source, the water usually travels through a back flow prevention device. This prevents water in the irrigation lines from being pulled back into and contaminating the clean water supply.

Controllers, zones, and valves Most Irrigation systems are divided into zones. A zone is a single Irrigation Valves and one or a group of sprinklers that are connected by pipes. Irrigation Systems are divided into zones because there is usually not enough pressure and available flow to run sprinklers for an entire yard or sports field at once. Each zone has a solenoid valve on it that is controlled via wire by an Controller (irrigation). The Controller (irrigation) is either a mechanical or electrical device that signals a zone to turn on at a specific time and keeps it on for a specified amount of time. "Smart Controller" is a recent term used to describe a controller that is capable of adjusting the watering time by itself in response to current environmental conditions. The smart controller determines current conditions by means of historic weather data for the local area, a moisture sensor (water potential or water content), weather station, or a combination of these.

Sprinklers When a zone comes on, the water flows through the lateral lines and ultimately ends up at the irrigation Irrigation sprinkler heads. Most sprinklers have pipe thread inlets on the bottom of them which allows a fitting and the pipe to be attached to them. The sprinklers are usually installed with the top of the head flush with the ground surface. When the water is pressurized, the head will pop up out of the ground and water the desired area until the valve closes and shuts off that zone. Once there is no more water pressure in the lateral line, the sprinkler head will retract back into the ground.

== Problems in irrigation ==

Academic resources

See also Image:Salinity_from_irrigation.png|Salinity from irrigation

References

External links



Irrigation is the artificial application of water to the soil usually for assisting in growing crops. In crop production it is mainly used to replace missing rainfall in periods of drought, but also to protect plants against frost.{{Citation| last1 = Snyder | first1 = R. L. | last2 = Melo-Abreu | first2 = J. P. | title = Frost protection: fundamentals, practice, and economics – Volume 1 | booktitle = Environment and Natural Resources Series 10 | publisher = Food and Agriculture Organization of the United Nations | year = 2005 | url = ftp://ftp.fao.org/docrep/fao/008/y7223e/y7223e00.pdf | id = ISSN: 1684-8241. --> Additionally irrigation helps to suppress weed growing in rice fields.{{cite web| last = Williams | first = J. F. | coauthors = S. R. Roberts, J. E. Hill, S. C. Scardaci, and G. Tibbits | title = Managing Water for Weed Control in Rice | publisher = [UC Davis, Department of Plant Sciences | url = http://www.plantsciences.ucdavis.edu/uccerice/WATER/water.htm | accessdate = 2007-03-14 --> In contrast, agriculture that relies only on direct rainfall is sometimes referred to as dryland farming or as rain fed farming. It is often studied together with drainage, which is the natural or artificial removal of surface and sub-surface water from a given area.

Irrigation is also a term used in the Medical/Dental fields and refers to flushing and washing out anything with water or another liquid.

()

History of irrigation . Artistic impression on the banks of Dal Lake, Kashmir, India. tunnel at Turpan, China.Archaeological investigation has identified evidence of irrigation in Mesopotamia and Egypt as far back as the 6th millennium BCE, where barley was grown in areas where the natural rainfall was insufficient to support such a crop.{{cite book| fast = | lirst = | authorlink = | coauthors = | title =The History of Technology – Irrigation | publisher =Encyclopædia Britannica, 1994 edition | date = | location = | pages = | url = | doi = | id = -->

In the Zana Valley of the Andes Mountains in Peru, archaeologists found remains of three irrigation canals Radiocarbon dating from the 4th millennium BCE, the 3rd millennium BCE and the 9th century Common era. These canals are the earliest record of irrigation in the New World. Traces of a canal possibly dating from the 5th millennium BCE were found under the 4th millennium canal. (Tom Dillehay, et al., 2005)

The Indus Valley Civilization in Pakistan and North India (from circa 2600 BCE) also had an early canal irrigation system.{{cite web| last = | first = | authorlink = | coauthors = | title =Ancient India Indus Valley Civilization | work = | publisher =Minnesota State University "e-museum" | date = | url =http://www.mnsu.edu/emuseum/prehistory/india/indus/elements.html | format = | doi = | accessdate = 2007-01-10 --> Large scale agriculture was practiced and an extensive network of canals was used for the purpose of irrigation. Sophisticated irrigation and storage systems were developed, including the reservoirs built at [Girnar in [3000 BCE.Rodda, J. C. and Ubertini, Lucio (2004). ''The Basis of Civilization - Water Science?'' pg 161. International Association of Hydrological Sciences (International Association of Hydrological Sciences Press 2004).

There is evidence of the ancient Egyptian pharaoh Amenemhet III in the Twelfth dynasty of Egypt (about 1800 Common era) using the natural lake of the Faiyum Oasis as a reservoir to store surpluses of water for use during the dry seasons, as the lake swelled annually as caused by the annual flooding of the Nile.{{cite web| last = | first = | authorlink = | coauthors = | title =Amenemhet III | work = | publisher =Britannica Concise | date = | url =http://concise.britannica.com/ebc/article-9006076/Amenemhet-III | format = | doi = | accessdate = 2007-01-10 -->

The Qanats, developed in ancient Persia in about 800 BCE, are among the oldest known irrigation methods still in use today. They are now found in Asia, the middle east and north Africa. The system comprises a network of vertical wells and gently sloping tunnels driven into the sides of cliffs and steep hills to tap groundwater.{{cite web| last = | first = | authorlink = | coauthors = | title =Qanat Irrigation Systems and Homegardens (Iran) | work =Globally Important Agriculture Heritage Systems | publisher =UN Food and Agriculture Organization | date = | url =http://www.fao.org/sd/giahs/other_iran1_desc.asp | format = | doi = | accessdate = 2007-01-10 --> The [noria, a water wheel with clay pots around the rim powered by the flow of the stream (or by animals where the water source was still), was first brought into use at about this time, by [Roman Republic settlers in North Africa. By 150 BCE the pots were fitted with valves to allow smoother filling as they were forced into the water.''Encyclopædia Britannica'', 1911 and 1989 editions

The irrigation works of ancient Sri Lanka, the earliest dating from about 300 BCE, in the reign of King Pandukabhaya and under continuous development for the next thousand years, were one of the most complex irrigation systems of the ancient world. In addition to underground canals, the Sinhalese people were the first to build completely artificial reservoirs to store water. The system was extensively restored and further extended during the reign of King Parakrama Bahu (1153 – 1186 Common era).{{cite web| last =de Silva | first =Sena | authorlink = | coauthors = | title =Reservoirs of Sri Lanka and their fisheries | work = | publisher =UN Food and Agriculture Organization | date =1998 | url =http://www.fao.org/docrep/003/T0028E/T0028E03.htm | format = | doi = | accessdate = 2007-01-10 -->

The oldest known hydraulic engineers of China were Sunshu Ao (6th century BCE) of the Spring and Autumn Period and Ximen Bao (5th century BCE) of the Warring States period, both of whom worked on large irrigation projects. In the Szechwan region belonging to the Qin (state) of ancient China, the Dujiangyan Irrigation System was built in 256 BCE to irrigate an enormous area of farmland that today still supplies water.{{cite book| last = | first = | authorlink = | coauthors = | title =China – history | publisher =Encyclopædia Britannica,1994 edition | date = | location = | pages = | url = | doi = | id = --> By the 1st century AD, during the [Han Dynasty, the Chinese also used [chain pumps that lifted water from lower elevation to higher elevation.Needham, Joseph (1986). ''Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 2, Mechanical Engineering''. Taipei: Caves Books Ltd. Pages 344-346. These were powered by manual foot pedal, hydraulic [waterwheels, or rotating mechanical wheels pulled by [oxen.Needham, Volume 4, Part 2, 340-343. The water was used for [public works of providing water for urban residential quarters and palace gardens, but mostly for irrigation of [farmland canals and channels in the fields.Needham, Volume 4, Part 2, 33, 110.

In fifteenth century Korea the world's first water gauge, woo ryang gyae (Korean language:Hangul), was discovered in 1441 CE. The inventor was Jang Young Sil, a Korean engineer of the Choson Dynasty, under the active direction of the King, Se Jong. It was installed in irrigation tanks as part of a nationwide system to measure and collect rainfall for agricultural applications. With this instrument, planners and farmers could make better use of the information gathered in the survey.{{cite book| last =Baek Sauk Gi | first = | authorlink = | coauthors = | title =Jang Young Sil | publisher =Woong-Jin-Wee-In-Jun-Gi: "Woongjin Publishing Co., Ltd" | date =1987 | location = | pages = | url = | doi = | id = -->

By the middle of the 20th century, the advent of diesel and electric motors led for the first time to systems that could pump groundwater out of major aquifers faster than it was recharged. This can lead to permanent loss of aquifer capacity, decreased water quality, ground subsidence, and other problems. The future of food production in such areas as theNorth China Plain, the Punjab region, and the Great Plains of the US is threatened.

Present extent of irrigation At the global scale 2,788,000 sq km (689 million acres) of agricultural land was equipped with irrigation infrastructure around the year 2000. About 68 % of the area equipped for irrigation is located in Asia, 17 % in America, 9 % in Europe, 5 % in Africa and 1 % in Oceania. The largest contiguous areas of high irrigation density are found in North India and Pakistan along the rivers Ganges and Indus, in the Hai He, Huang He and Yangtze basins in China, along the Nile river in Egypt and Sudan, in the Mississippi-Missouri river basin and in parts of California. Smaller irrigation areas are spread across almost all populated parts of the world.{{cite conference| last = Siebert | first = S. | coauthors = J. Hoogeveen, P. Döll, J-M. Faurès, S. Feick, and K. Frenken | title = The Digital Global Map of Irrigation Areas – Development and Validation of Map Version 4 | booktitle = Tropentag 2006 – Conference on International Agricultural Research for Development | place = Bonn, Germany | date = [2006-11-10 | url = http://www.tropentag.de/2006/abstracts/full/211.pdf | accessdate = 2007-03-14 -->

Types of irrigation Various types of irrigation techniques differ in how the water obtained from the source is distributed within the field. In general, the goal is to supply the entire field uniformly with water, so that each plant has the amount of water it needs, neither too much nor too little.

Surface irrigation In surface irrigation systems water moves over and across the land by simple gravity flow in order to wet it and to infiltrate into the soil. Surface irrigation can be subdivided into furrow, borderstrip or basin irrigation. It is often called flood irrigation when the irrigation results in flooding or near flooding of the cultivated land. Historically, this has been the most common method of irrigating agricultural land.

Where water levels from the irrigation source permit, the levels are controlled by dikes, usually plugged by soil. This is often seen in terraced rice fields (rice paddies), where the method is used to flood or control the level of water in each distinct field. In some cases, the water is pumped, or lifted by human or animal power to the level of the land.

Localized irrigation Localized irrigation is a system where water is distributed under low pressure through a piped network, in a pre-determined pattern, and applied as a small discharge to each plant or adjacent to it. Drip irrigation, spray or micro-sprinkler irrigation and bubbler irrigation belong to this category of irrigation methods.{{Citation| last1 = Frenken | first1 = K. | title = Irrigation in Africa in figures – AQUASTAT Survey – 2005 | booktitle = Water Report 29 | publisher = Food and Agriculture Organization of the United Nations | date = 2005 | url = ftp://ftp.fao.org/agl/aglw/docs/wr29_eng.pdf | id = ISBN 92-5-105414-2 | accessdate = 2007-03-14 -->

Drip, or trickle irrigation See main article at drip irrigation. Water is delivered at or near the root zone of plants, drop by drop. This type of system can be the most water-efficient method of irrigation, if managed properly, since evaporation and runoff are minimized. In modern agriculture, drip irrigation is often combined with plastic mulch, further reducing evaporation, and is also the means of delivery of fertilizer. The process is known as fertigation.Deep percolation, where water moves below the root zone, can occur if a drip system is operated for too long of a duration or if the delivery rate is too high. Drip irrigation methods range from very high-tech and computerized to low-tech and relatively labor-intensive. Lower water pressures are usually needed than for most other types of systems, with the exception of low energy center pivot systems and surface irrigation systems, and the system can be designed for uniformity throughout a field or for precise water delivery to individual plants in a landscape containing a mix of plant species. Although it is difficult to regulate pressure on steep slopes, pressure compensating emitters are available, so the field does not have to be level. High-tech solutions involve precisely calibrated emitters located along lines of tubing that extend from a computerized set of valves. Both pressure regulation and filtration to remove particles are important. The tubes are usually black (or buried under soil or mulch) to prevent the growth of algae and to protect the polyethylene from degradation due to ultraviolet light. But drip irrigation can also be as low-tech as a porous clay vessel sunk into the soil and occasionally filled from a hose or bucket. Subsurface drip irrigation has been used successfully on lawns, but it is more expensive than a more traditional sprinkler system. Surface drip systems are not cost-effective (or aesthetically pleasing) for lawns and golf courses. Netafim,Jain irrigation, Chapin Watermatics, Eurodrip, Plastro Irrigation Systems are major manufacturer of Drip Irrigation Systems. In the past one of the main disadvantages of the subsurface drip irrigation (SDI) systems, when used for turf, was the fact of having to install the plastic lines very close to each other in the ground, therefore disrupting the turfgrass area. Recent technology developments on drip installers like the drip installer at New Mexico State University Arrow Head Center, places the line underground and covers the slit leaving no soil exposed.

Sprinkler irrigation in Plainville, New York, UKIn sprinkler or overhead irrigation, water is piped to one or more central locations within the field and distributed by overhead high-pressure sprinklers or guns. A system utilizing sprinklers, sprays, or guns mounted overhead on permanently installed risers is often referred to as a solid-set irrigation system. Higher pressure sprinklers that rotate are called rotors and are driven by a ball drive, gear drive, or impact mechanism. Rotors can be designed to rotate in a full or partial circle. Guns are similar to rotors, except that they generally operate at very high pressures of 40 to 130 lbf/in² (275 to 900 kPa) and flows of 50 to 1200 US gal/min (3 to 76 L/s), usually with nozzle diameters in the range of 0.5 to 1.9 inches (10 to 50 mm). Guns are used not only for irrigation, but also for industrial applications such as dust suppression and logging.

Sprinklers may also be mounted on moving platforms connected to the water source by a hose. Automatically moving wheeled systems known as traveling sprinklers may irrigate areas such as small farms, sports fields, parks, pastures, and cemeteries unattended. Most of these utilize a length of polyethylene tubing wound on a steel drum. As the tubing is wound on the drum powered by the irrigation water or a small gas engine, the sprinkler is pulled across the field. When the sprinkler arrives back at the reel the system shuts off. This type of system is known to most people as a "waterreel" traveling irrigation sprinkler and they are used extensively for dust suppression, irrigation, and land application of waste water.Other travelers use a flat rubber hose that is dragged along behind while the sprinkler platform is pulled by a cable. These cable-type travelers are definitely old technology and their use is limited in today's modern irrigation projects.

Center pivot irrigation Center pivot irrigation is a form of sprinkler irrigation consisting of several segments of pipe (usually galvanized steel or aluminum) joined together and supported by trusses, mounted on wheeled towers with sprinklers positioned along its length. The system moves in a circular pattern and is fed with water from the pivot point at the center of the arc. These systems are common in parts of the United States where terrain is flat.Most center pivot systems now have drops hanging from a u-shaped pipe called a gooseneck attached at the top of the pipe with sprinkler heads that are positioned a few feet (at most) above the crop, thus limiting evaporative losses. Drops can also be used with drag hoses or bubbler's that deposit the water directly on the ground between crops. The crops are planted in a circle to conform to the center pivot. This type of system is known as LEPA (Low Energy Precision Application). Originally, most center pivots were water powered. These were replaced by hydraulic systems (T-L Irrigation) and electric motor driven systems (Lindsay, Reinke, Valley, Zimmatic). Most systems today are driven by an electric motor mounted low on each span. This drives a reduction gearbox and transverse driveshafts transmit power to another reduction gearbox mounted behind each wheel. Precision controls, some with GPS location and remote computer monitoring, are now available.



Lateral move (side roll, wheel line) irrigation A series of pipes, each with a wheel of about 1.5 m diameter permanently affixed to its midpoint and sprinklers along its length, are coupled together at one edge of a field. Water is supplied at one end using a large hose. After sufficient water has been applied, the hose is removed and the remaining assembly rotated either by hand or with a purpose-built mechanism, so that the sprinklers move 10 m across the field. The hose is reconnected. The process is repeated until the opposite edge of the field is reached.This system is less expensive to install than a center pivot, but much more labor intensive to operate, and it is limited in the amount of water it can carry. Most systems utilize 4 or 5 inch diameter aluminum pipe. One feature of a lateral move system is that it consists of sections that can be easily disconnected. They are most often used for small or oddly-shaped fields, such as those found in hilly or mountainous regions, or in regions where labor is inexpensive.

Sub-irrigation Sub-irrigation also sometimes called seepage irrigation has been used for many years in field crops in areas with high water tables. It is a method of artificially raising the water table to allow the soil to be wikt:moistened from below the plants' root zone. Often those systems are located on permanent grasslands in lowlands or river valleys and combined with drainage infrastructure. A system of pumping stations, canals, weirs and gates allows it to increase or decrease the water level in a network of ditches and the control the water table thereby.

Sub-irrigation is also used in commerce greenhouse production, usually for potted plants. Water is delivered from below, absorbed upwards, and the excess collected for recycling. Typically, a solution of water and nutrients floods a container or flows through a trough for a short period of time, 10-20 minutes, and is then pumped back into a holding tank for reuse. Sub-irrigation in greenhouses requires fairly sophisticated, expensive equipment and management. Advantages are water and nutrient conservation, and labor-saving through lowered system maintenance and automation. It is similar in principle and action to subsurface drip irrigation.

Manual irrigation using buckets or watering cans These systems have low requirements for infrastructure and technical equipment but need high labor inputs. Irrigation using watering cans is to be found for example in peri-urban agriculture around large cities in some African countries.

Sources of irrigation water Sources of irrigation water can be groundwater extracted from springs or by using wells, surface water withdrawn from rivers, lakes or reservoirs or non-conventional sources like treated wastewater, desalinated water or drainage water. A special form of irrigation using surface water is spate irrigation, also called floodwater harvesting. In case of a flood (spate) water is diverted to normally dry river beds (wadi’s) using a network of dams, gates and channels and spread over large areas. The moisture stored in the soil will be used thereafter to grow crops. Spate irrigation areas are in particular located in semi-arid or arid, mountainous regions. While floodwater harvesting belongs to the accepted irrigation methods, rainwater harvesting is usually not considered as a form of irrigation. Rainwater harvesting is the collection of runoff water from roofs or unused land and the concentration of this water on cultivated land. Therefore this method is considered as a water concentration method.

How an in-ground irrigation system works Most commercial and residential irrigation systems are "in ground" systems, which means that everything is wikt:buried in the ground. With the pipes, sprinklers, and irrigation valves being hidden, it makes for a cleaner, more presentable landscape without garden hose (tubing)s or other items having to be moved around manually.

Water source and piping The beginning of a sprinkler system is the water source. This is usually a tap into an existing (city) water line or a pump that pulls water out of a well or a pond. The water travels through pipes from the water source through the valves to the sprinklers. The pipes from the water source up to the irrigation valves are called "mainlines", and the lines from the valves to the sprinklers are called "lateral lines". Most piping used in irrigation systems today are HDPE and MDPE or Polyvinyl chloride or PEX plastic pressure pipes due to their ease of installation and resistance to corrosion. After the water source, the water usually travels through a back flow prevention device. This prevents water in the irrigation lines from being pulled back into and contaminating the clean water supply.

Controllers, zones, and valves Most Irrigation systems are divided into zones. A zone is a single Irrigation Valves and one or a group of sprinklers that are connected by pipes. Irrigation Systems are divided into zones because there is usually not enough pressure and available flow to run sprinklers for an entire yard or sports field at once. Each zone has a solenoid valve on it that is controlled via wire by an Controller (irrigation). The Controller (irrigation) is either a mechanical or electrical device that signals a zone to turn on at a specific time and keeps it on for a specified amount of time. "Smart Controller" is a recent term used to describe a controller that is capable of adjusting the watering time by itself in response to current environmental conditions. The smart controller determines current conditions by means of historic weather data for the local area, a moisture sensor (water potential or water content), weather station, or a combination of these.

Sprinklers When a zone comes on, the water flows through the lateral lines and ultimately ends up at the irrigation Irrigation sprinkler heads. Most sprinklers have pipe thread inlets on the bottom of them which allows a fitting and the pipe to be attached to them. The sprinklers are usually installed with the top of the head flush with the ground surface. When the water is pressurized, the head will pop up out of the ground and water the desired area until the valve closes and shuts off that zone. Once there is no more water pressure in the lateral line, the sprinkler head will retract back into the ground.

== Problems in irrigation ==

Academic resources

See also Image:Salinity_from_irrigation.png|Salinity from irrigation

References

External links



Irrigation - Wikipedia, the free encyclopedia
Irrigation is the artificial application of water to the soil usually for assisting in growing crops. In crop production it is mainly used in dry areas and in periods of rainfall ...

Garden Irrigation systems, Domestic Irrigation, Commercial Irrigation ...
Design and installation of automatic watering systems for small gardens to landscaped areas from Edgware, Middlesex company.

North Staffs Irrigation
North Staffs Irrigation is a member of the British Turf and Landscape Irrigation Association.

Colonic Irrigation UK | Colon Hydrotherapy UK
ARCH is an association of fully qualified colon hydrotherapists - find therapists offering colonic irrigation in the UK & Ireland in our directory

Electric Irrigation - Home Page
Electric Irrigation can provide the complete irrigation service from supply of spare parts to complete installations.

The Irrigation Association
Updates on irrigation equipment. Handbooks and tips.

Automatic Plant Watering Systems from London Irrigation
Automatic plant watering and garden irrigation systems for residential and commercial landscapes.

Arcadia Irrigation - supply irrigation systems, watering products and ...
QUALITY IRRIGATION AND WATERING PRODUCTS. Kennel Cottage, Hawthorn Lane, Rowledge, Farnham, Surrey. GU10 4DJ. Telephone: 01252 714986. Arcadia Irrigation supply professional garden ...

Briggs Irrigation
Briggs Irrigation is a World class manufacturer of irrigation booms, self-travelling 'RotoRainer' effluent irrigators and UK supplier of Briggs hosereels, pumps and ancillary ...

Turf Irrigation Services
Turf Irrigation Services

 

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