Editing Agriculture (section)

=== Land and water issues ===
{{See also|Environmental impact of irrigation}}
[[File:Share Of Water Withdrawal By Agriculture In Total Withdrawal, Top Countries (2020).svg|thumb|440x440px|Countries with the highest share of water withdrawal by agriculture in total withdrawal.]]
[[File:Crops Kansas AST 20010624.jpg|thumb|upright=1.1|Circular [[irrigated]] crop fields in [[Haskell County, Kansas|Kansas]]. Healthy, growing crops of [[maize|corn]] and [[sorghum]] are green (sorghum may be slightly paler). Wheat is brilliant gold. Fields of brown have been recently harvested and plowed or have lain in [[fallow]] for the year.]]

Land transformation, the use of land to yield goods and services, is the most substantial way humans alter the Earth's ecosystems, and is the driving force causing [[biodiversity loss]]. Estimates of the amount of land transformed by humans vary from 39 to 50%.<ref name="Vitousek">{{cite journal |last1=Vitousek |first1=P. M. |last2=Mooney |first2=H. A. |last3=Lubchenco |first3=J. |last4=Melillo |first4=J. M. |year=1997 |title=Human Domination of Earth's Ecosystems |journal=[[Science (journal)|Science]] |volume=277 |pages=494–499 |doi=10.1126/science.277.5325.494 |issue=5325 |citeseerx=10.1.1.318.6529 |s2cid=8610995}}</ref> It is estimated that 24% of land globally experiences land degradation, a long-term decline in ecosystem function and productivity, with cropland being disproportionately affected.<ref name="FAO GLADA">{{cite web |last1=Bai |first1=Z.G. |last2=Dent |first2=D.L. |last3=Olsson |first3=L. |last4=Schaepman |first4=M.E. |name-list-style=amp |date=November 2008 |title=Global assessment of land degradation and improvement: 1. identification by remote sensing |publisher=[[Food and Agriculture Organization]]/ISRIC |url=http://www.isric.org/isric/webdocs/docs/Report%202008_01_GLADA%20international_REV_Nov%202008.pdf |access-date=24 May 2013 |url-status=dead |archive-url=https://web.archive.org/web/20131213041558/http://www.isric.org/isric/webdocs/docs/Report%202008_01_GLADA%20international_REV_Nov%202008.pdf |archive-date=13 December 2013}}</ref> Land management is the driving factor behind degradation; 1.5&nbsp;billion people rely upon the degrading land. Degradation can be through deforestation, [[desertification]], [[soil erosion]], mineral depletion, [[soil acidification|acidification]], or [[Soil salinity|salinization]].<ref name="CS" /> In 2021, the global agricultural land area was 4.79 billion hectares (ha), down 2 percent, or 0.09 billion ha compared with 2000. Between 2000 and 2021, roughly two-thirds of agricultural land were used for permanent meadows and pastures (3.21 billion ha in 2021), which declined by 5 percent (0.17 billion ha). One-third of the total agricultural land was cropland (1.58 billion ha in 2021), which increased by 6 percent (0.09 billion ha).<ref name=":14"/>

[[Eutrophication]], excessive nutrient enrichment in [[aquatic ecosystem]]s resulting in [[algal bloom]]s and [[anoxic waters|anoxia]], leads to [[fish kill]]s, [[loss of biodiversity]], and renders water unfit for drinking and other industrial uses. Excessive fertilization and manure application to cropland, as well as high livestock stocking densities cause nutrient (mainly [[nitrogen]] and [[phosphorus]]) [[surface runoff|runoff]] and [[leaching (agriculture)|leaching]] from agricultural land. These nutrients are major [[nonpoint source pollution|nonpoint pollutants]] contributing to [[eutrophication]] of aquatic ecosystems and pollution of groundwater, with harmful effects on human populations.<ref name="Eutr">{{cite journal |last1=Carpenter |first1=S. R. |last2=Caraco |first2=N. F. |last3=Correll |first3=D. L. |last4=Howarth |first4=R. W. |last5=Sharpley |first5=A. N. |last6=Smith |first6=V. H. |year=1998 |title=Nonpoint Pollution of Surface Waters with Phosphorus and Nitrogen |journal=Ecological Applications |volume=8 |pages=559–568 |doi=10.1890/1051-0761(1998)008[0559:NPOSWW]2.0.CO;2 |issue=3 |hdl=1808/16724 |hdl-access=free}}</ref> Fertilizers also reduce terrestrial biodiversity by increasing competition for light, favoring those species that are able to benefit from the added nutrients.<ref name="Hautier Niklaus Hector">{{cite journal |last1=Hautier |first1=Y. |last2=Niklaus |first2=P. A. |last3=Hector |first3=A. |title=Competition for Light Causes Plant Biodiversity Loss After Eutrophication |journal=Science |volume=324 |issue=5927 |date=2009 |doi=10.1126/science.1169640 |pmid=19407202 |pages=636–638 |bibcode=2009Sci...324..636H |s2cid=21091204 |url=https://www.zora.uzh.ch/id/eprint/18666/2/Hautier_2009.pdf |type=Submitted manuscript |access-date=3 November 2018 |archive-date=2 November 2018 |archive-url=https://web.archive.org/web/20181102011324/https://www.zora.uzh.ch/id/eprint/18666/2/Hautier_2009.pdf |url-status=live}}</ref>

Agriculture simultaneously is facing growing freshwater demand and precipitation anomalies (droughts, floods, and extreme rainfall and weather events) on rainfed areas fields and grazing lands.<ref name=":9" /> Agriculture accounts for 70 percent of withdrawals of freshwater resources,<ref>{{cite web |editor-last=Molden |editor-first=D. |url=http://www.iwmi.cgiar.org/About_IWMI/Strategic_Documents/Annual_Reports/2006_2007/pdf/IWMI%20Annual%20Report%202006-07.pdf |title=Findings of the Comprehensive Assessment of Water Management in Agriculture |website=Annual Report 2006/2007 |publisher=[[International Water Management Institute]] |access-date=6 January 2014 |url-status=live |archive-url=https://web.archive.org/web/20140107031305/http://www.iwmi.cgiar.org/About_IWMI/Strategic_Documents/Annual_Reports/2006_2007/pdf/IWMI%20Annual%20Report%202006-07.pdf |archive-date=7 January 2014}}</ref><ref>{{Cite book |title=On Water |url=https://www.eib.org/en/publications/eib-big-ideas-on-water |access-date=7 December 2020 |year=2019 |doi=10.2867/509830 |author1=European Investment Bank |author2=Arthus-Bertrand, Yann |publisher=Publications Office of the European Union |isbn=978-9286143199 |archive-date=29 November 2020 |archive-url=https://web.archive.org/web/20201129051604/https://www.eib.org/en/publications/eib-big-ideas-on-water |url-status=live}}</ref> and an estimated 41 percent of current global irrigation water use occurs at the expense of environmental flow requirements.<ref name=":9" /> It is long known that aquifers in areas as diverse as northern China, the [[Ganges|Upper Ganges]] and the western US are being depleted, and new research extends these problems to aquifers in Iran, Mexico and Saudi Arabia.<ref>{{cite web |url=http://green.blogs.nytimes.com/2012/08/13/stressed-aquifers-around-the-globe/ |title=Stressed Aquifers Around the Globe |last=Li |first=Sophia |date=13 August 2012 |access-date=7 May 2013 |website=[[The New York Times]] |url-status=live |archive-url=https://web.archive.org/web/20130402141530/http://green.blogs.nytimes.com/2012/08/13/stressed-aquifers-around-the-globe/ |archive-date=2 April 2013}}</ref> Increasing pressure is being placed on water resources by industry and urban areas, meaning that [[water scarcity]] is increasing and agriculture is facing the challenge of producing more food for the world's growing population with reduced water resources.<ref>{{cite web |url=http://www.fao.org/ag/magazine/0511sp2.htm |title=Water Use in Agriculture |date=November 2005 |publisher=[[Food and Agriculture Organization]] |access-date=7 May 2013 |url-status=dead |archive-url=https://archive.today/20130615091527/http://www.fao.org/ag/magazine/0511sp2.htm |archive-date=15 June 2013}}</ref> While industrial withdrawals have declined in the past few decades and municipal withdrawals have increased only marginally since 2010, agricultural withdrawals have continued to grow at an ever faster pace.<ref name=":9" /> [[Farm water|Agricultural water]] usage can also cause major environmental problems, including the destruction of natural wetlands, the spread of water-borne diseases, and land degradation through salinization and waterlogging, when irrigation is performed incorrectly.<ref>{{cite web |url=http://www.fao.org/ag/magazine/0303sp1.htm |title=Water Management: Towards 2030 |date=March 2003 |publisher=[[Food and Agriculture Organization]] |access-date=7 May 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130510184315/http://www.fao.org/ag/magazine/0303sp1.htm |archive-date=10 May 2013}}</ref>