Editing Irrigation (section)

== Water sources ==

=== Groundwater and surface water ===
[[File:Bisse.jpg|thumb|[[Bisse d'Ayent|Traditional irrigation channel]] in Switzerland, collecting water from the high Alps]]
[[File:Pump-enabled Riverside Irrigation in Comilla, Bangladesh, 25 April 2014.jpg|thumb|right|Irrigation is underway by [[Pump|pump-enabled]] extraction directly from [[Gumti River (Tripura)|the Gumti]], seen in the background, in [[Comilla District|Comilla]], Bangladesh.]]
[[File:Vale do São Francisco Pernanbuco.jpg|thumb|Grapes in [[Petrolina]], Brazil only made possible in this [[semi arid]] area by [[drip irrigation]]]]

Irrigation water can come from [[groundwater]] (extracted from [[Spring (hydrosphere)|springs]] or by using [[Water well|wells]]), from surface water (withdrawn from [[river]]s, [[lake]]s or [[reservoirs]]) or from non-conventional sources like [[reclaimed water|treated wastewater]], [[desalinated water]], [[drainage|drainage water]], or [[fog collection]].

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.

=== Treated or untreated wastewater ===

{{excerpt|Reclaimed water#Agricultural reuse}}

{{excerpt|Reclaimed water#Risks in agricultural reuse}}

=== Other sources ===
Irrigation water can also come from non-conventional sources like [[reclaimed water|treated wastewater]],<ref>{{cite journal |last1=Moreira da Silva |first1=Manuela |last2=Resende |first2=Flávia C. |last3=Freitas |first3=Bárbara |last4=Aníbal |first4=Jaime |last5=Martins |first5=António |last6=Duarte |first6=Amílcar |title=Urban Wastewater Reuse for Citrus Irrigation in Algarve, Portugal—Environmental Benefits and Carbon Fluxes |journal=Sustainability |date=January 2022 |volume=14 |issue=17 |pages=10715 |doi=10.3390/su141710715|doi-access=free |bibcode=2022Sust...1410715M |hdl=10400.1/18203 |hdl-access=free }}</ref> [[desalinated water]], [[drainage|drainage water]], or [[fog collection]].

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 collection|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|2019|November}} 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]], [[Suaeda|sea blite]], and [[Tripolium pannonicum|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]].<ref name="Reuters-saltwater">{{cite web |last=McDill |first=Stuart |date=November 27, 2019 |title=Startup helps Scottish farmers grow gourmet plants with sea water |url=https://www.reuters.com/article/us-climate-change-saltwater-farming/startup-helps-scottish-farmers-grow-gourmet-plants-with-sea-water-idUSKBN1Y01V6 |access-date=2 December 2019 |website=Reuters |publisher=Thomson Reuters |quote=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.}}</ref><ref name="thenational.scot-saltwater">{{cite web |last=O'Toole |first=Emer |date=29 July 2019 |title=Seawater Solutions is tacking agriculture's impact on climate change |url=https://www.thenational.scot/news/17800385.climate-change-scottish-firm-tackling-effects-agriculture/ |access-date=2 December 2019 |website=The National |publisher=Newsquest Media Group Ltd |quote=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.}}</ref>

=== Competition for water resources ===
{{Main|Water scarcity}}
Until the 1960s, there were fewer than half the number of people on the planet as of 2024. People were not as wealthy as today, consumed fewer calories and [[meat consumption|ate less meat]], so less water was needed to produce their food. They required a third of the volume of water humans presently take from rivers. Today, the competition for [[water resources]] is much more intense, because there are now [[population growth|more than seven billion people]] on the planet, increasing the likelihood of [[overconsumption]] of food produced by water-thirsty animal agriculture and [[intensive farming]] practices. This creates increasing competition for water from [[Industrial sector|industry]], [[urbanisation]] and [[biofuel crops]]. Farmers will have to strive to increase productivity to meet growing [[food security|demands for food]], while industry and cities find ways to use water more efficiently.<ref>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</ref>

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.