Irrigation

Last updated
The hub of a center-pivot irrigation system Center-pivot irrigation.jpg
The hub of a center-pivot irrigation system

Irrigation is the process of applying controlled amounts of water to plants at needed intervals. Irrigation helps to grow agricultural crops, maintain landscapes, and revegetate disturbed soils in dry areas and during periods of less than average rainfall. Irrigation also has other uses in crop production, including frost protection, [1] suppressing weed growth in grain fields [2] and preventing soil consolidation. [3] In contrast, agriculture that relies only on direct rainfall is referred to as rain-fed.

Contents

Irrigation systems are also used for cooling livestock, dust suppression, disposal of sewage, and in mining. Irrigation is often studied together with drainage, which is the removal of surface and sub-surface water from a given area.

Irrigation canal in Osmaniye, Turkey Osmaniye irrigation.JPG
Irrigation canal in Osmaniye, Turkey
Sprinkler irrigation of blueberries in Plainville, New York, United States Irrigated blueberries4046.jpg
Sprinkler irrigation of blueberries in Plainville, New York, United States

Irrigation has been a central feature of agriculture for over 5,000 years and is the product of many cultures. Historically, it was the basis for economies and societies across the globe, from Asia to the Southwestern United States.

History

Animal-powered irrigation, Upper Egypt, ca. 1846 David Roberts ancient fountain.jpg
Animal-powered irrigation, Upper Egypt, ca. 1846

Archaeological investigation has found evidence of irrigation in areas lacking sufficient natural rainfall to support crops for rainfed agriculture. The earliest known use of the technology dates to the 6th millennium BCE in Khuzistan in the south-west of present-day Iran. [4] [5]

Irrigation was used as a means of manipulation of water in the alluvial plains of the Indus valley civilization, the application of it is estimated to have begun around 4500 BC and drastically increased the size and prosperity of their agricultural settlements. [6] The Indus Valley Civilization developed sophisticated irrigation and water-storage systems, including artificial reservoirs at Girnar dated to 3000 BCE, and an early canal irrigation system from c. 2600 BCE. Large-scale agriculture was practiced, with an extensive network of canals used for the purpose of irrigation. [6] [7]

Farmers in the Mesopotamian plain used irrigation from at least the third millennium BCE. [8] They developed perennial irrigation, regularly watering crops throughout the growing season by coaxing water through a matrix of small channels formed in the field. [9] Ancient Egyptians practiced basin irrigation using the flooding of the Nile to inundate land plots which had been surrounded by dykes. The flood water remained until the fertile sediment had settled before the engineers returned the surplus to the watercourse. [10] There is evidence of the ancient Egyptian pharaoh Amenemhet III in the twelfth dynasty (about 1800 BCE) using the natural lake of the Faiyum Oasis as a reservoir to store surpluses of water for use during dry seasons. The lake swelled annually from the flooding of the Nile. [11]

Young engineers restoring and developing the old Mughal irrigation system in 1847 during the reign of the Mughal Emperor Bahadur Shah II Scene at Bhimgoda near Haridwar , February 1847.jpg
Young engineers restoring and developing the old Mughal irrigation system in 1847 during the reign of the Mughal Emperor Bahadur Shah II

The Ancient Nubians developed a form of irrigation by using a waterwheel-like device called a sakia . Irrigation began in Nubia some time between the third and second millennia BCE. [12] It largely depended upon the flood waters that would flow through the Nile River and other rivers in what is now the Sudan. [13]

Irrigation in Tamil Nadu, India Peanuts irrigation.jpg
Irrigation in Tamil Nadu, India

In sub-Saharan Africa irrigation reached the Niger River region cultures and civilizations by the first or second millennium BCE and was based on wet-season flooding and water harvesting. [14] [15]

Evidence of terrace irrigation occurs in pre-Columbian America, early Syria, India, and China. [10] In the Zana Valley of the Andes Mountains in Peru, archaeologists have found remains of three irrigation canals radiocarbon-dated from the 4th millennium BCE, the 3rd millennium BCE and the 9th century CE. These canals provide 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. [16]

Ancient Persia (modern day Iran) used irrigation as far back as the 6th millennium BCE to grow barley in areas with insufficient natural rainfall. [17] [ need quotation to verify ] The Qanats, developed in ancient Persia 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 of steep hills to tap groundwater. [18] 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), first came into use at about this time among Roman settlers in North Africa. By 150 BCE the pots were fitted with valves to allow smoother filling as they were forced into the water. [19]

Sri Lanka

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 were the first to build completely artificial reservoirs to store water.[ citation needed ] These reservoirs and canal systems were used primarily to irrigate paddy fields, which require a lot of water to cultivate. Most of these irrigation systems still exist undamaged up to now, in Anuradhapura and Polonnaruwa, because of the advanced and precise engineering. The system was extensively restored and further extended[ by whom? ] during the reign of King Parakrama Bahu (1153–1186 CE). [20]

China

Inside a karez tunnel at Turpan, Xinjiang, China Turpan-karez-museo-d02.jpg
Inside a karez tunnel at Turpan, Xinjiang, China

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 Sichuan region belonging to the state of Qin of ancient China, the Dujiangyan Irrigation System devised by the Qin Chinese hydrologist and irrigation engineer Li Bing was built in 256 BCE to irrigate a vast area of farmland that today still supplies water. [21] By the 2nd century AD, during the Han Dynasty, the Chinese also used chain pumps which lifted water from a lower elevation to a higher one. [22] These were powered by manual foot-pedal, hydraulic waterwheels, or rotating mechanical wheels pulled by oxen. [23] The water was used for public works, providing water for urban residential quarters and palace gardens, but mostly for irrigation of farmland canals and channels in the fields. [24]

Korea

Korea, Jang Yeong-sil, a Korean engineer of the Joseon Dynasty, under the active direction of the king, Sejong the Great, invented the world's first rain-gauge, uryanggye (Korean:우량계) in 1441. It was installed in irrigation tanks[ by whom? ] 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[ which? ] survey. [25]

North America

Irrigation ditch in Montour County, Pennsylvania Irrigation ditch in Montour County, Pennsylvania.JPG
Irrigation ditch in Montour County, Pennsylvania

The earliest agricultural irrigation canal system known in the area of the present-day United States dates to between 1200 B.C. and 800 B.C. and was discovered by Desert Archaeology, Inc. in Marana, Arizona (adjacent to Tucson) in 2009. [26] The irrigation-canal system predates the Hohokam culture by two thousand years and belongs to an unidentified culture. In North America, the Hohokam were the only culture known to rely on irrigation canals to water their crops, and their irrigation systems supported the largest population in the Southwest by AD 1300. The Hohokam constructed an assortment of simple canals combined with weirs in their various agricultural pursuits. Between the 7th and 14th centuries they built and maintained extensive irrigation networks along the lower Salt and middle Gila Rivers that rivaled the complexity of those used in the ancient Near East, Egypt, and China. These were constructed using relatively simple excavation tools, without the benefit of advanced engineering technologies, and achieved drops of a few feet per mile, balancing erosion and siltation. The Hohokam cultivated varieties of cotton, tobacco, maize, beans and squash, as well as harvesting an assortment of wild plants. Late in the Hohokam Chronological Sequence, they also used extensive dry-farming systems, primarily to grow agave for food and fiber. Their reliance on agricultural strategies based on canal irrigation, vital in their less-than-hospitable desert environment and arid climate, provided the basis for the aggregation of rural populations into stable urban centers. [27] [ need quotation to verify ]

Present extent

Share of agricultural land which is irrigated (2015) Share of agricultural land which is irrigated, OWID.svg
Share of agricultural land which is irrigated (2015)

In year 2000, the total fertile land was 2,788,000 km² (689 million acres) and it was equipped with irrigation infrastructure worldwide. About 68% of this area is in Asia, 17% in the Americas, 9% in Europe, 5% in Africa and 1% in Oceania. The largest contiguous areas of high irrigation density are found:

  • In Northern India and Pakistan along the Ganges and Indus rivers
  • 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, the Southern Great Plains, and in parts of California

Smaller irrigation areas are spread across almost all populated parts of the world. [28]

Water gardens in sigiriya Sigiriya WaterGardens.JPG
Water gardens in sigiriya

By 2012, the area of irrigated land had increased to an estimated total of 3,242,917 km² (801 million acres), which is nearly the size of India. [29]

Types of irrigation

There are several methods of irrigation. They vary in how the water is supplied to the plants. The goal is to apply the water to the plants as uniformly as possible, so that each plant has the amount of water it needs, neither too much nor too little.

Surface irrigation

Basin flood irrigation of wheat LevelBasinFloodIrrigation.JPG
Basin flood irrigation of wheat

Surface irrigation is the oldest form of irrigation and has been in use for thousands of years. In surface ( flood, or level basin) irrigation systems, water moves across the surface of an agricultural lands, in order to wet it and infiltrate into the soil. Surface irrigation can be subdivided into furrow, border strip 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 and is still used in most parts of the world.

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. The water application efficiency of surface irrigation is typically lower than other forms of irrigation.

Residential flood irrigation in Phoenix, Arizona Residential flood irrigation in Phoenix, Arizona, in the United States of America.jpg
Residential flood irrigation in Phoenix, Arizona

Surface irrigation is even used to water landscapes in certain areas, for example, in and around Phoenix, Arizona. The irrigated area is surrounded by a berm and the water is delivered according to a schedule set by a local irrigation district. [30]

Micro-irrigation

Drip irrigation - a dripper in action Dripperwithdrop.png
Drip irrigation – a dripper in action

Micro-irrigation, sometimes called localized irrigation, low volume irrigation, or trickle 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. Traditional drip irrigation use individual emitters, subsurface drip irrigation (SDI), micro-spray or micro-sprinklers, and mini-bubbler irrigation all belong to this category of irrigation methods. [31]

Drip irrigation

Drip irrigation layout and its parts Dripirrigation.gif
Drip irrigation layout and its parts
Micro-sprinkler Sprinkler Irrigation - Sprinkler head.JPG
Micro-sprinkler

Drip (or micro) irrigation, also known as trickle irrigation, functions as its name suggests. In this system water falls drop by drop just at the position of roots. Water is delivered at or near the root zone of plants, drop by drop. This method can be the most water-efficient method of irrigation, [32] if managed properly, evaporation and runoff are minimized. The field water efficiency of drip irrigation is typically in the range of 80 to 90 percent when managed correctly.

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 or if the delivery rate is too high. Drip irrigation methods range from very high-tech and computerized to low-tech and 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.

Sprinkler irrigation

Crop sprinklers near Rio Vista, California Crop sprinklers Rio Vista California 15 Jul 2004-002.jpg
Crop sprinklers near Rio Vista, California
A traveling sprinkler at Millets Farm Centre, Oxfordshire, United Kingdom TravellingSprinkler.JPG
A traveling sprinkler at Millets Farm Centre, Oxfordshire, United Kingdom

In 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 using 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 275 to 900 kPa (40 to 130 psi) and flows of 3 to 76 L/s (50 to 1200 US gal/min), usually with nozzle diameters in the range of 10 to 50 mm (0.5 to 1.9 in). Guns are used not only for irrigation, but also for industrial applications such as dust suppression and logging.

Sprinklers can 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 use 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.

Center pivot

A small center pivot system from beginning to end Center Pivot.jpg
A small center pivot system from beginning to end
Rotator style pivot applicator sprinkler Nelson A3000 Accelerator.png
Rotator style pivot applicator sprinkler
Center pivot with drop sprinklers PivotWithDrops.JPG
Center pivot with drop sprinklers
Wheel line irrigation system in Idaho, 2001 WheelLineIrrigation.JPG
Wheel line irrigation system in Idaho, 2001
Center pivot irrigation Crop Triangle South Africa.jpg
Center pivot irrigation

Center pivot irrigation is a form of sprinkler irrigation utilising several segments of pipe (usually galvanized steel or aluminium) joined together and supported by trusses, mounted on wheeled towers with sprinklers positioned along its length. [33] 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 found and used in all parts of the world and allow irrigation of all types of terrain. Newer systems have drop sprinkler heads as shown in the image that follows.

As of 2017 most center pivot systems have drops hanging from a U-shaped pipe 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 bubblers that deposit the water directly on the ground between crops. Crops are often 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 (Reinke, Valley, Zimmatic). Many modern pivots feature GPS devices. [34]

Irrigation by lateral move (side roll, wheel line, wheelmove) [35] [36]

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. Water is supplied at one end using a large hose. After sufficient irrigation has been applied to one strip of the field, the hose is removed, the water drained from the system, and the assembly rolled either by hand or with a purpose-built mechanism, so that the sprinklers are moved to a different position across the field. The hose is reconnected. The process is repeated in a pattern until the whole field has been irrigated.

This system is less expensive to install than a center pivot, but much more labor-intensive to operate – it does not travel automatically across the field: it applies water in a stationary strip, must be drained, and then rolled to a new strip. Most systems use 100 or 130 mm (4 or 5 inch) diameter aluminum pipe. The pipe doubles both as water transport and as an axle for rotating all the wheels. A drive system (often found near the centre of the wheel line) rotates the clamped-together pipe sections as a single axle, rolling the whole wheel line. Manual adjustment of individual wheel positions may be necessary if the system becomes misaligned.

Wheel line systems are limited in the amount of water they can carry, and limited in the height of crops that can be irrigated. One useful feature of a lateral move system is that it consists of sections that can be easily disconnected, adapting to field shape as the line is moved. They are most often used for small, rectilinear, or oddly-shaped fields, hilly or mountainous regions, or in regions where labor is inexpensive.

Lawn sprinkler systems

A lawn sprinkler system is permanently installed, as opposed to a hose-end sprinkler, which is portable. Sprinkler systems are installed in residential lawns, in commercial landscapes, for churches and schools, in public parks and cemeteries, and on golf courses. Most of the components of these irrigation systems are hidden under ground, since aesthetics are important in a landscape. A typical lawn sprinkler system will consist of one or more zones, limited in size by the capacity of the water source. Each zone will cover a designated portion of the landscape. Sections of the landscape will usually be divided by microclimate, type of plant material, and type of irrigation equipment. A landscape irrigation system may also include zones containing drip irrigation, bubblers, or other types of equipment besides sprinklers.

Although manual systems are still used, most lawn sprinkler systems may be operated automatically using an irrigation controller, sometimes called a clock or timer. Most automatic systems employ electric solenoid valves. Each zone has one or more of these valves that are wired to the controller. When the controller sends power to the valve, the valve opens, allowing water to flow to the sprinklers in that zone.

There are two main types of sprinklers used in lawn irrigation, pop-up spray heads and rotors. Spray heads have a fixed spray pattern, while rotors have one or more streams that rotate. Spray heads are used to cover smaller areas, while rotors are used for larger areas. Golf course rotors are sometimes so large that a single sprinkler is combined with a valve and called a 'valve in head'. When used in a turf area, the sprinklers are installed with the top of the head flush with the ground surface. When the system 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 pressure in the lateral line, the sprinkler head will retract back into the ground. In flower beds or shrub areas, sprinklers may be mounted on above ground risers or even taller pop-up sprinklers may be used and installed flush as in a lawn area.

An impact sprinkler watering a lawn, an example of a hose-end sprinkler Irrigational sprinkler.jpg
An impact sprinkler watering a lawn, an example of a hose-end sprinkler

Hose-end sprinklers

There are many types of hose-end sprinklers. Many of them are smaller versions of larger agricultural and landscape sprinklers, sized to work with a typical garden hose. Some have a spiked base allowing them to be temporarily stuck in the ground, while others have a sled base designed to be dragged while attached to the hose.

Subirrigation

Subirrigation 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 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 thereby control the water table.

Subirrigation is also used in the commercial greenhouse production, usually for potted plants. Water is delivered from below, absorbed by 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 savings through reduced system maintenance and automation. It is similar in principle and action to subsurface basin irrigation.

Another type of subirrigation is the self-watering container, also known as a sub-irrigated planter. This consists of a planter suspended over a reservoir with some type of wicking material such as a polyester rope. The water is drawn up the wick through capillary action. [37] [38] A similar technique is the wicking bed; this too uses capillary action.

Subsurface textile irrigation

Diagram showing the structure of an example SSTI installation SSTI Cross-Section.png
Diagram showing the structure of an example SSTI installation

Subsurface Textile Irrigation (SSTI) is a technology designed specifically for subirrigation in all soil textures from desert sands to heavy clays. A typical subsurface textile irrigation system has an impermeable base layer (usually polyethylene or polypropylene), a drip line running along that base, a layer of geotextile on top of the drip line and, finally, a narrow impermeable layer on top of the geotextile (see diagram). Unlike standard drip irrigation, the spacing of emitters in the drip pipe is not critical as the geotextile moves the water along the fabric up to 2 m from the dripper. The impermeable layer effectively creates an artificial water table.

Water sources

Irrigation is underway by pump-enabled extraction directly from the Gumti, seen in the background, in Comilla, Bangladesh. Pump-enabled Riverside Irrigation in Comilla, Bangladesh, 25 April 2014.jpg
Irrigation is underway by pump-enabled extraction directly from the Gumti, seen in the background, in Comilla, Bangladesh.

Irrigation water can come from groundwater (extracted from springs or by using wells), from surface water (withdrawn from rivers, lakes or reservoirs) or from non-conventional sources like treated wastewater, desalinated water, drainage water, or fog collection. 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 (wadis) 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.

Around 90% of wastewater produced globally remains untreated, causing widespread water pollution, especially in low-income countries. Increasingly, agriculture uses untreated wastewater as a source of irrigation water. Cities provide lucrative markets for fresh produce, so are attractive to farmers. However, because agriculture has to compete for increasingly scarce water resources with industry and municipal users (see Water scarcity below), there is often no alternative for farmers but to use water polluted with urban waste, including sewage, directly to water their crops. Significant health hazards can result from using water loaded with pathogens in this way, especially if people eat raw vegetables that have been irrigated with the polluted water. The International Water Management Institute has worked in India, Pakistan, Vietnam, Ghana, Ethiopia, Mexico and other countries on various projects aimed at assessing and reducing risks of wastewater irrigation. They advocate a 'multiple-barrier' approach to wastewater use, where farmers are encouraged to adopt various risk-reducing behaviours. These include ceasing irrigation a few days before harvesting to allow pathogens to die off in the sunlight, applying water carefully so it does not contaminate leaves likely to be eaten raw, cleaning vegetables with disinfectant or allowing fecal sludge used in farming to dry before being used as a human manure. [39] The World Health Organization has developed guidelines for safe water use.

In countries where humid air sweeps through at night, water can be obtained by condensation onto cold surfaces. This is practiced in the vineyards at Lanzarote using stones to condense water. Fog collectors are also made of canvas or foil sheets. Using condensate from air conditioning units as a water source is also becoming more popular in large urban areas.

As of November 2019 a Glasgow-based startup has helped a farmer in Scotland to establish edible saltmarsh crops irrigated with sea water. An acre of previously marginal land has been put under cultivation to grow samphire, sea blite, and sea aster; these plants yield a higher profit than potatoes. The land is flood irrigated twice a day to simulate tidal flooding; the water is pumped from the sea using wind power. Additional benefits are soil remediation and carbon sequestration. [40] [41]

Grapes in Petrolina, only made possible in this semi arid area by drip irrigation Vale do Sao Francisco Pernanbuco.jpg
Grapes in Petrolina, only made possible in this semi arid area by drip irrigation

Efficiency

Modern irrigation methods are efficient enough 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. [42] Water use efficiency in the field can be determined as follows:

Until 1960s, water was not recognised as a scarce resource. At that time, there were fewer than half the current number of people on the planet. People were not as wealthy as today, consumed fewer calories and ate less meat, so less water was needed to produce their food. They required a third of the volume of water we presently take from rivers. Today, the competition for water resources is much more intense. This is because there are now more than seven billion people on the planet, their consumption of water-thirsty meat and vegetables is rising, and there is increasing competition for water from industry, urbanisation and biofuel crops. To avoid a global water crisis, farmers will have to strive to increase productivity to meet growing demands for food, while industry and cities find ways to use water more efficiently. [43]

Successful agriculture is dependent upon farmers having sufficient access to water. However, water scarcity is already a critical constraint to farming in many parts of the world. With regards to agriculture, the World Bank targets food production and water management as an increasingly global issue that is fostering a growing debate. [44] Physical water scarcity is where there is not enough water to meet all demands, including that needed for ecosystems to function effectively. Arid regions frequently suffer from physical water scarcity. It also occurs where water seems abundant but where resources are over-committed. This can happen where there is overdevelopment of hydraulic infrastructure, usually for irrigation. Symptoms of physical water scarcity include environmental degradation and declining groundwater. Economic scarcity, meanwhile, is caused by a lack of investment in water or insufficient human capacity to satisfy the demand for water. Symptoms of economic water scarcity include a lack of infrastructure, with people often having to fetch water from rivers for domestic and agricultural uses. Some 2.8 billion people currently live in water-scarce areas. [45]

Technical challenges

Irrigation schemes involve solving numerous engineering and economic problems while minimizing negative environmental consequences. [46] Such problems include:

Impact on society

A 2016 study found that countries whose agriculture depended on irrigation are more likely to be autocratic than other countries. The authors of the study "argue that the effect has historical origins: irrigation allowed landed elites in arid areas to monopolize water and arable land. This made elites more powerful and better able to oppose democratization." [58]

See also

Related Research Articles

Center pivot irrigation Method of crop irrigation

Center-pivot irrigation, also called water-wheel and circle irrigation, is a method of crop irrigation in which equipment rotates around a pivot and crops are watered with sprinklers. A circular area centered on the pivot is irrigated, often creating a circular pattern in crops when viewed from above. Most center pivots were initially water-powered, however today most are propelled by electric motors.

Soil salinity The salt content in the soil

Soil salinity is the salt content in the soil; the process of increasing the salt content is known as salinization. Salts occur naturally within soils and water. Salination can be caused by natural processes such as mineral weathering or by the gradual withdrawal of an ocean. It can also come about through artificial processes such as irrigation and road salt.

Water conservation Policies for sustainable development of water use

Water conservation includes all the policies, strategies and activities to sustainably manage the natural resource of fresh water, to protect the hydrosphere, and to meet the current and future human demand. Population, household size and growth and affluence all affect how much water is used. Factors such as climate change have increased pressures on natural water resources especially in manufacturing and agricultural irrigation. Many countries have already implemented policies aimed at water conservation, with much success.

Drip irrigation in agriculture and gardening

Drip irrigation is a type of micro-irrigation system that has the potential to save water and nutrients by allowing water to drip slowly to the roots of plants, either from above the soil surface or buried below the surface. The goal is to place water directly into the root zone and minimize evaporation. Drip irrigation systems distribute water through a network of valves, pipes, tubing, and emitters. Depending on how well designed, installed, maintained, and operated it is, a drip irrigation system can be more efficient than other types of irrigation systems, such as surface irrigation or sprinkler irrigation.

Irrigation sprinkler Method of irrigating lawns and crops

An irrigation sprinkler is a device used to irrigate agricultural crops, lawns, landscapes, golf courses, and other areas. They are also used for cooling and for the control of airborne dust. Sprinkler irrigation is the method of applying water in a controlled manner in way similar to rainfall. The water is distributed through a network that may consist of pumps, valves, pipes, and sprinklers.

Fertigation

Fertigation is the injection of fertilizers, used for soil amendments, water amendments and other water-soluble products into an irrigation system.

Desert farming

Desert farming is the practice of developing agriculture in deserts. As agriculture depends upon irrigation and water supply, farming in arid regions where water is scarce is a challenge. However, desert farming has been practiced by humans for thousands of years. In the Negev Desert, there is evidence to suggest agriculture as far back as 5000 BC. Today, the Imperial Valley in southern California, Australia, Saudi Arabia, Israel and Palestine are examples of modern desert agriculture. Water efficiency has been important to the growth of desert agriculture. Water reuse, desalination, and drip irrigation are all modern ways that regions and countries have expanded their agriculture despite being in an arid climate.

Irrigation in Australia

Irrigation is a widespread practice required in many areas of Australia, the driest inhabited continent, to supplement low rainfall with water from other sources to assist in growing crops and pasture. Overuse or poor management of irrigation is held responsible by some for environmental problems such as soil salinity and loss of habitat for native flora and fauna.

During the Sangam age, 500 BCE – 300 CE, agriculture was the main vocation of the Tamils. It was considered a necessity for life, and hence was treated as the foremost among all occupations. The farmers or the Ulavar were placed right at the top of the social classification. As they were the producers of food grains, they lived with self-respect. Agriculture during the early stages of Sangam period was primitive, but it progressively got more efficient with improvements in irrigation, ploughing, manuring, storage and distribution. The ancient Tamils were aware of the different varieties of soil, the kinds of crops that can be grown on them and the various irrigation schemes suitable for a given region. These were also in Madras, Thanjore.

Waru Waru is an Aymara term for the agricultural technique developed by pre-Hispanic people in the Andes region of South America from Colombia to Bolivia; this regional agricultural technique is also referred to as camellones in Spanish. Functionally similar agricultural techniques have been developed in other parts of the world, all of which fall under the broad category of raised field agriculture.

Lift irrigation

Lift irrigation is a method of irrigation in which water is not transported by natural flow, but is lifted with pumps or surge pools etc.

Surface irrigation

Surface irrigation is where water is applied and distributed over the soil surface by gravity. It is by far the most common form of irrigation throughout the world and has been practiced in many areas virtually unchanged for thousands of years.

Environmental impact of irrigation

The environmental impacts of irrigation relate to the changes in quantity and quality of soil and water as a result of irrigation and the effects on natural and social conditions in river basins and downstream of an irrigation scheme. The impacts stem from the altered hydrological conditions caused by the installation and operation of the irrigation scheme.

This page shows statistical data on irrigation of agricultural lands worldwide.
Irrigation is the artificial abstraction of water from a source followed by the distribution of it at scheme level aiming at application at field level to enhance crop production when rainfall is scarce.

Irrigation in Iran covers 89,930 km2 making it the fifth ranked country in terms of irrigated area.

Irrigation in viticulture

Irrigation in viticulture is the process of applying extra water in the cultivation of grapevines. It is considered both controversial and essential to wine production. In the physiology of the grapevine, the amount of available water affects photosynthesis and hence growth, as well as the development of grape berries. While climate and humidity play important roles, a typical grape vine needs 25-35 inches of water a year, occurring during the spring and summer months of the growing season, to avoid stress. A vine that does not receive the necessary amount of water will have its growth altered in a number of ways; some effects of water stress are considered desirable by wine grape growers.

Agriculture in the prehistoric Southwestern United States

The agricultural practices of the Native Americans inhabiting the American Southwest, which includes the states of Arizona and New Mexico plus portions of surrounding states and neighboring Mexico, are influenced by the low levels of precipitation in the region. Irrigation and several techniques of water harvesting and conservation were essential for successful agriculture. To take advantage of limited water, the southwestern Native Americans utilized irrigation canals, terraces (trincheras), rock mulches, and floodplain cultivation. Success in agriculture enabled some native Americans to live in communities which may have numbered as many as 40,000 people as compared to their former lives as hunter-gatherers in which their bands numbered only a few dozen.

Micro-irrigation

Micro-irrigation, also called localized irrigation, low volume irrigation, low-flow irrigation, or trickle irrigation, is an irrigation method with lower pressure and flow than a traditional sprinkler system. Low volume irrigation is used in agriculture for row crops, orchards, and vineyards. It is also used in horticulture in wholesale nurseries, in landscaping for civic, commercial, and private landscapes and gardens, and in the science and practice of restoration ecology and environmental remediation.

Subsurface textile irrigation

Subsurface Textile Irrigation (SSTI) is a technology designed specifically for subsurface irrigation in all soil textures from desert sands to heavy clays. Use of SSTI will significantly reduce the usage of water, fertilizer and herbicide. It will lower on-going operational costs and, if maintained properly, will last for decades. By delivering water and nutrients directly to the root zone, plants are healthier and have a far greater yield.

Salt tolerance of crops

Salt tolerance of crops is the maximum salt level a crop tolerates without losing its productivity while it is affected negatively at higher levels. The salt level is often taken as the soil salinity or the salinity of the irrigation water.

References

  1. Snyder, R. L.; Melo-Abreu, J. P. (2005). Frost protection: fundamentals, practice, and economics. Volume 1. Food and Agriculture Organization of the United Nations. ISBN   978-92-5-105328-7. ISSN   1684-8241.
  2. Williams, J. F.; S. R. Roberts; J. E. Hill; S. C. Scardaci; G. Tibbits. "Managing Water for 'Weed' Control in Rice". UC Davis, Department of Plant Sciences. Archived from the original on 2007-04-03. Retrieved 2007-03-14.
  3. "Arid environments becoming consolidated" . Retrieved 2012-06-19.
  4. Flannery, Kent V. (1969). "Origins and ecological effects of early domestication in Iran and the Near East". In Ucko, Peter John; Dimbleby, G. W. (eds.). The Domestication and Exploitation of Plants and Animals. New Brunswick, New Jersey: Transaction Publishers (published 2007). p. 89. ISBN   9780202365572 . Retrieved 2019-01-12.
  5. Lawton, H. W.; Wilke, P. J. (1979). "Ancient Agricultural Systems in Dry Regions of the Old World". In Hall, A. E.; Cannell, G. H.; Lawton, H.W. (eds.). Agriculture in Semi-Arid Environments. Ecological Studies. 34 (reprint ed.). Berlin: Springer Science & Business Media (published 2012). p. 13. ISBN   9783642673283 . Retrieved 2019-01-12.
  6. 1 2 Rodda, J. C.; Ubertini, Lucio, eds. (2004). The Basis of Civilization--water Science?. International Association of Hydrological Science. ISBN   9781901502572.
  7. "Ancient India Indus Valley Civilization". Minnesota State University "e-museum". Archived from the original on 2007-02-05. Retrieved 2007-01-10.
  8. Crawford, Harriet, ed. (2013). The Sumerian World. Routledge Worlds. Abingdon, Oxfordshire: Routledge. ISBN   9781136219115 . Retrieved 2019-01-12.
  9. Hill, Donald (1984). "2: Irrigation and Water supply". A History of Engineering in Classical and Medieval Times (reprint ed.). London: Routledge (published 2013). p. 18. ISBN   9781317761570 . Retrieved 2019-01-12.
  10. 1 2 p19 Hill
  11. "Amenemhet III". Britannica Concise. Archived from the original on 2007-05-10. Retrieved 2007-01-10.
  12. G. Mokhtar (1981-01-01). Ancient civilizations of Africa. Unesco. International Scientific Committee for the Drafting of a General History of Africa. p. 309. ISBN   9780435948054 . Retrieved 2012-06-19 via Books.google.com.
  13. Bulliet, Richard; Crossley, Pamela Kyle; Headrick, Daniel; Hirsch, Steven (2008-06-18). The Earth and Its Peoples, Volume I: A Global History, to 1550. pp. 53–56. ISBN   978-0618992386.
  14. "Traditional technologies". Fao.org. Retrieved 2012-06-19.
  15. "Africa, Emerging Civilizations In Sub-Sahara Africa. Various Authors; Edited By: R. A. Guisepi". History-world.org. Archived from the original on 2010-06-12. Retrieved 2012-06-19.
  16. Dillehay TD, Eling HH Jr, Rossen J (2005). "Preceramic irrigation canals in the Peruvian Andes". Proceedings of the National Academy of Sciences. 102 (47): 17241–4. Bibcode:2005PNAS..10217241D. doi:10.1073/pnas.0508583102. PMC   1288011 . PMID   16284247.CS1 maint: multiple names: authors list (link)
  17. The History of Technology – Irrigation. Encyclopædia Britannica, 1994 edition.
  18. "Qanat Irrigation Systems and Homegardens (Iran)". Globally Important Agriculture Heritage Systems. UN Food and Agriculture Organization. Retrieved 2007-01-10.
  19. Encyclopædia Britannica, 1911 and 1989 editions
  20. de Silva, Sena (1998). "Reservoirs of Sri Lanka and their fisheries". UN Food and Agriculture Organization. Retrieved 2007-01-10.
  21. China – history. Encyclopædia Britannica,1994 edition.
  22. 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.
  23. Needham, Volume 4, Part 2, 340–343.
  24. Needham, Volume 4, Part 2, 33, 110.
  25. Baek Seok-gi 백석기 (1987). Jang Yeong-sil 장영실. Woongjin Wiin Jeon-gi 웅진위인전기 11. Woongjin Publishing Co., Ltd.
  26. "Earliest Canals in America – Archaeology Magazine Archive".
  27. James M. Bayman, "The Hohokam of Southwest North America." Journal of World Prehistory 15.3 (2001): 257–311.
  28. Siebert, S.; J. Hoogeveen, P. Döll, J-M. Faurès, S. Feick, and K. Frenken (2006-11-10). "The Digital Global Map of Irrigation Areas – Development and Validation of Map Version 4" (PDF). Tropentag 2006 – Conference on International Agricultural Research for Development. Bonn, Germany. Retrieved 2007-03-14.CS1 maint: multiple names: authors list (link)
  29. "The World". The World Factbook . Central Intelligence Agency . Retrieved 23 May 2019.
  30. "Flood Irrigation Service". City of Tempe, Arizona. Retrieved 29 July 2017.
  31. Frenken, K. (2005). Irrigation in Africa in figures – AQUASTAT Survey – 2005 (PDF). Food and Agriculture Organization of the United Nations. ISBN   978-92-5-105414-7 . Retrieved 2007-03-14.[ permanent dead link ]
  32. Provenzano, Giuseppe (2007). "Using HYDRUS-2D Simulation Model to Evaluate Wetted Soil Volume in Subsurface Drip Irrigation Systems". Journal of Irrigation and Drainage Engineering. 133 (4): 342–350. doi:10.1061/(ASCE)0733-9437(2007)133:4(342).
  33. Mader, Shelli (May 25, 2010). "Center pivot irrigation revolutionizes agriculture". The Fence Post Magazine. Archived from the original on September 8, 2016. Retrieved June 6, 2012.
  34. Gaines, Tharran (January 7, 2017). "GPS SWING ARMS PROVE THEIR WORTH". Successful Farming. Retrieved February 1, 2018.
  35. Peters, Troy. "Managing Wheel ‐ Lines and Hand ‐ Lines for High Profitability" (PDF). Archived from the original (PDF) on 21 October 2016. Retrieved 29 May 2015.
  36. Hill, Robert. "Wheelmove Sprinkler Irrigation Operation and Management" (PDF). Retrieved 29 May 2015.
  37. "Polyester ropes natural irrigation technique". Entheogen.com. Archived from the original on April 12, 2012. Retrieved 2012-06-19.
  38. "DIY instructions for making self-watering system using ropes". Instructables.com. 2008-03-17. Retrieved 2012-06-19.
  39. Wastewater use in agriculture: Not only an issue where water is scarce! International Water Management Institute, 2010. Water Issue Brief 4
  40. McDill, Stuart (November 27, 2019). "Startup helps Scottish farmers grow gourmet plants with sea water". Reuters. Thomson Reuters. Retrieved 2 December 2019. Seawater Solutions is helping farmers on Scotland’s west coast adapt to the reality of less rain by choosing salt-resistant plants and developing saltmarshes - land flooded by tidal waters - for them to grow in.
  41. O'Toole, Emer (29 July 2019). "Seawater Solutions is tacking agriculture's impact on climate change". The National. Newsquest Media Group Ltd. Retrieved 2 December 2019. A system of farming that creates wetland ecosystems on which food can be grown, while carbon is captured at a rate of up to 40 times higher than the same area of rainforest, and profits are more than eight times more profitable than the average potato field.
  42. "Water use efficiency - agriwaterpedia.info".
  43. Chartres, C. and Varma, S. Out of water. From Abundance to Scarcity and How to Solve the World's Water Problems FT Press (USA), 2010
  44. "Reengaging in Agricultural Water Management: Challenges and Options". The World Bank. pp. 4–5. Retrieved 2011-10-30.
  45. Molden, D. (Ed). Water for food, Water for life: A Comprehensive Assessment of Water Management in Agriculture. Earthscan/IWMI, 2007.
  46. ILRI, 1989, Effectiveness and Social/Environmental Impacts of Irrigation Projects: a Review. In: Annual Report 1988, International Institute for Land Reclamation and Improvement (ILRI), Wageningen, The Netherlands, pp. 18 – 34 . On line:
  47. Rosegrant, Mark W., and Hans P. Binswanger. "Markets in tradable water rights: potential for efficiency gains in developing country water resource allocation." World development (1994) 22#11 pp: 1613–1625.
  48. "A new report says we're draining our aquifers faster than ever". High Country News. 2013-06-22. Retrieved 2014-02-11.
  49. "Management of aquifer recharge and discharge processes and aquifer storage equilibrium" (PDF).
  50. EOS magazine, September 2009
  51. World Water Council
  52. Hukkinen, Janne, Emery Roe, and Gene I. Rochlin. "A salt on the land: A narrative analysis of the controversy over irrigation-related salinity and toxicity in California's San Joaquin Valley." Policy Sciences 23.4 (1990): 307–329. online Archived 2015-01-02 at the Wayback Machine
  53. Drainage Manual: A Guide to Integrating Plant, Soil, and Water Relationships for Drainage of Irrigated Lands. Interior Dept., Bureau of Reclamation. 1993. ISBN   978-0-16-061623-5.
  54. "Free articles and software on drainage of waterlogged land and soil salinity control in irrigated land" . Retrieved 2010-07-28.
  55. UV treatment http://www.uvo3.co.uk/?go=Irrigation_Water
  56. ultrasonic algae control http://www.lgsonic.com/irrigation-water-treatment/
  57. Venot, Jean-Philippe (2017-07-06). Drip Irrigation for Agriculture. doi:10.4324/9781315537146. ISBN   9781315537146.
  58. Bentzen, Jeanet Sinding; Kaarsen, Nicolai; Wingender, Asger Moll (2016-06-01). "Irrigation and Autocracy". Journal of the European Economic Association: n/a. doi:10.1111/jeea.12173. ISSN   1542-4774.

Further reading

Journals