Irrigation is the application of controlled amounts of water to plants
at needed intervals.
Irrigation helps 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,
suppressing weed growth in grain fields and preventing soil
consolidation. In contrast, agriculture that relies only on direct
rainfall is referred to as rain-fed or dry land farming.
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
Sprinkler irrigation of blueberries in Plainville, New York, United
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.
1.3 North America
2 Present extent
3 Types of irrigation
3.1 Surface irrigation
3.2.1 Drip irrigation
3.3 Sprinkler irrigation
3.3.1 Center pivot
Irrigation by Lateral move (side roll, wheel line,
3.3.3 Lawn sprinkler systems
3.3.4 Hose-end sprinklers
3.4.1 Subsurface textile irrigation
6 Technical challenges
7 Impact on society
8 See also
10 Further reading
11 External links
Animal-powered irrigation, Upper Egypt, ca. 1846
Archaeological investigation has found evidence of irrigation where
natural rainfall was insufficient to support crops for rainfed
Perennial irrigation was practiced in the Mesopotamian plain whereby
crops were regularly watered throughout the growing season by coaxing
water through a matrix of small channels formed in the field.
Ancient Egyptians practiced Basin irrigation using the flooding of the
Nile to inundate land plots which had been surrounded by dykes. The
flood water was held until the fertile sediment had settled before the
surplus was returned to the watercourse. 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 the dry seasons. The lake
swelled annually from flooding of the Nile.
Young engineers restoring and developing the old Mughal irrigation
system 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
time between the third and second millennium BCE. It largely
depended upon the flood waters that would flow through the
and other rivers in what is now the Sudan.
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.
Terrace irrigation is evidenced in pre-Columbian America, early Syria,
India, and China. In the Zana Valley of the
Andes Mountains in
Peru, archaeologists found remains of three irrigation canals
radiocarbon dated from the 4th millennium BCE, the 3rd millennium BCE
and the 9th century CE. These canals are the earliest record of
irrigation in the New World. Traces of a canal possibly dating from
5th millennium BCE
5th millennium BCE were found under the 4th millennium canal.
Sophisticated irrigation and storage systems were developed by the
Indus Valley Civilization
Indus Valley Civilization in present-day Pakistan and North India,
including the reservoirs at
Girnar in 3000 BCE and an early canal
irrigation system from circa 2600 BCE. Large scale agriculture
was practiced and an extensive network of canals was used for the
purpose of irrigation.
Ancient Persia (modern day Iran) used irrigation as far back as the
6th millennium BCE
6th millennium BCE to grow barley in areas where natural rainfall was
insufficient. 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. 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 settlers in North Africa. By 150 BCE the pots were fitted with
valves to allow smoother filling as they were forced into the
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. Due to their engineering superiority in
this sector, they were often called 'masters of irrigation'.[by whom?]
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
during the reign of King
Parakrama Bahu (1153–1186 CE).
Inside a karez tunnel at Turpan, Xinjiang, China
The oldest known hydraulic engineers of
Sunshu Ao (6th
century BCE) of the
Spring and Autumn period
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
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. By the 2nd century AD, during the Han
Dynasty, the Chinese also used chain pumps that lifted water from a
lower elevation to a higher one. These were powered by manual foot
pedal, hydraulic waterwheels, or rotating mechanical wheels pulled by
oxen. 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.
In 15th century Korea, the world's first rain gauge, uryanggye
(Korean:우량계), was invented in 1441. The inventor was Jang
Yeong-sil, a Korean engineer of the
Joseon Dynasty, under the active
direction of the king, Sejong the Great. 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
Irrigation ditch in Montour County, Pennsylvania
Main article: Hohokam
The earliest agricultural irrigation canal system known in the U.S.
dates to between 1200 B.C. and 800 B.C. and was discovered in Marana,
Arizona (adjacent to Tucson) in 2009. The irrigation canal system
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 also 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 harvested 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.
Irrigation of land in Punjab, India
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
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.
Only eight years later, in 2008, the area of irrigated land had
increased to an estimated total of 3,245,566 km² (802 million
acres), which is nearly the size of India.
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.
Main article: Surface irrigation
Basin flood irrigation of wheat
Surface irrigation is the oldest form of irrigation and has been in
use for thousands of years. In surface (furrow, flood, or level basin)
irrigation systems, water moves across the surface of an agricultural
lands, in an order to wet it and 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 and 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
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.
Main article: Micro-irrigation
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 using individual
emitters, subsurface drip irrigation (SDI), micro-spray or
micro-sprinkler irrigation, and mini-bubbler irrigation all belong to
this category of irrigation methods.
Drip irrigation layout and its parts
Main article: Drip irrigation
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, 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
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
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.
Crop sprinklers near Rio Vista, California
A traveling sprinkler at Millets Farm Centre, Oxfordshire, United
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 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 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
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.
A small center pivot system from beginning to end
Rotator style pivot applicator sprinkler
Center pivot with drop sprinklers
Wheel line irrigation system in Idaho, 2001
Main article: Center pivot irrigation
Center pivot irrigation
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. 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[update] 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
Irrigation by Lateral move (side roll, wheel line,
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 4 or 5-inch
(130 mm) 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
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 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 commercial 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 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
Subsurface textile irrigation
Main article: Subsurface textile irrigation
Diagram showing the structure of an example SSTI installation
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.
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
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
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.
World Health Organization
World Health Organization has developed guidelines for safe water
There are numerous benefits of using recycled water for irrigation,
including the low cost (when compared to other sources, particularly
in an urban area), consistency of supply (regardless of season,
climatic conditions and associated water restrictions), and general
consistency of quality.
Irrigation of recycled wastewater is also
considered as a means for plant fertilization and particularly
nutrient supplementation. This approach carries with it a risk of soil
and water pollution through excessive wastewater application. Hence, a
detailed understanding of soil water conditions is essential for
effective utilization of wastewater for irrigation.
In countries where humid air sweeps through at night, water can be
obtained by condensation onto cold surfaces. This is practiced in the
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.
Grapes in Petrolina, only made possible in this semi arid area by drip
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.
Water use efficiency in
the field can be determined as follows:
Water Efficiency (%) = (
Water Transpired by Crop ÷ Water
Applied to Field) x 100
Until 1960s, the common perception was that water was an infinite
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.
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
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.
Main article: Environmental impact of irrigation
Irrigation schemes involve solving numerous engineering and economic
problems while minimizing negative environmental impact.
Competition for surface water rights.
Overdrafting (depletion) of underground aquifers. In the mid-20th
century, the advent of diesel and electric motors led to systems that
could pump groundwater out of major aquifers faster than drainage
basins could refill them. 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 the North
China Plain, the Punjab, and the
Great Plains of the US is threatened
by this phenomenon.
Ground subsidence (e.g. New Orleans, Louisiana)
Underirrigation or irrigation giving only just enough water for the
plant (e.g. in drip line irrigation) gives poor soil salinity control
which leads to increased soil salinity with consequent buildup of
toxic salts on soil surface in areas with high evaporation. This
requires either leaching to remove these salts and a method of
drainage to carry the salts away. When using drip lines, the leaching
is best done regularly at certain intervals (with only a slight excess
of water), so that the salt is flushed back under the plant's
Overirrigation because of poor distribution uniformity or management
wastes water, chemicals, and may lead to water pollution.
Deep drainage (from over-irrigation) may result in rising water tables
which in some instances will lead to problems of irrigation salinity
requiring watertable control by some form of subsurface land
Irrigation with saline or high-sodium water may damage soil structure
owing to the formation of alkaline soil
Clogging of filters: It is mostly algae that clog filters, drip
installations and nozzles. UV and ultrasonic method can be
used for algae control in irrigation systems.
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
Agriculture and Agronomy portal
Environmental impact of irrigation
Lift irrigation schemes
List of countries by irrigated land area
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Encyclopædia Britannica (11th ed.). Cambridge University Press.
Water resources management and irrigation by country
Brazil - supply
Brazil - irrigation
List of countries by irrigated land area
Agricultural water management
Irrigation environmental impacts
Drainage system (agriculture)
Drainage by wells
Hydrological transport model
Runoff model (reservoir)
Groundwater energy balance
Acid sulphate soils
Soil salinity control
Leaching model (soil)
SaltMod integrated model
SahysMod polygonal model: Saltmod coupled to a groundwater model
Pollution / quality
Ambient standards (USA)
Clean Air Act (USA)
Fossil fuels (peak oil)
Non-timber forest products
Types / location
storage and recovery
Earth Overshoot Day
Renewable / Non-renewable
Agriculture and agronomy
Acid mine drainage
Adsorbable organic halides
Biochemical oxygen demand
Chemical oxygen demand
Total dissolved solids
Total suspended solids
Agricultural wastewater treatment
API oil-water separator
Decentralized wastewater system
Fecal sludge management
Industrial wastewater treatment
Rotating biological contactor
Sewage sludge treatment
Ultraviolet germicidal irradiation
Wastewater treatment plant
Septic drain field
New Stone Age
New World crops
Ard / plough
Mortar and pestle
Bow and arrow
Game drive system
Langdale axe industry
British megalith architecture
Nordic megalith architecture
Neolithic long house
Abri de la Madeleine
Alp pile dwellings
Wattle and daub
Megalithic architectural elements
Arts and culture
Art of the Upper Paleolithic
Art of the Middle Paleolithic
Stone Age art
Bradshaw rock paintings
Carved Stone Balls
Cup and ring mark
British Isles and Brittany
Mound Builders culture
Stone box grave
Unchambered long cairn
Origin of language
Divje Babe flute
Origin of religion
Spiritual drug use