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[[Image:040719 172 dorset marnhull2.jpg|thumb|220px|Modern arable agriculture typically uses large [[field (agriculture)|fields]] like this one in [[Dorset]], [[England]].]]


== October 2008 ==
In [[geography]], '''arable land''' (from [[Latin]] ''arare'', to [[plough]]) is an [[agriculture|agricultural]] term, meaning [[land (economics)|land]] that can be used for growing [[agriculture|crops]]. There is not much arable land japan.


[[Image:Information.png|25px]] Welcome to Wikipedia. The <span class="plainlinks">[http://en.wikipedia.org/wiki/Flour?diff=244418685 recent edit]</span> you made to [[:Flour]] has been reverted, as it appears to be unconstructive. Use the [[Wikipedia:Sandbox|sandbox]] for testing; if you believe the edit was constructive, ensure that you provide an informative [[Help:Edit summary|edit summary]]. You may also wish to read the [[Wikipedia:Introduction|introduction to editing]]. Thank you. <!-- Template:uw-huggle1 --> [[User:Antonio_Lopez|<span style='color: #339933;font-family:courier new;'>Antonio Lopez</span>]] <sup> [[User_talk:Antonio_Lopez|<span style='color: #ff0000;text-decoration:underline;'>(desu)</span>]] </sup> 18:33, 10 October 2008 (UTC)

Of the earth's 148,940,000&nbsp;km² (57.5 million square miles) of land, approximately 19,824,000&nbsp;km² (7.65 million square miles) are arable.<ref>CIA Factbook 2008</ref> However, arable land is currently being lost at the rate of over 100,000 km² (38,610 square miles) per year. A major element of arable land loss comes from [[deforestation]] (starting in the [[Middle Ages]] in [[Europe]] as well as [[Asia]]). Such deforestation continues to the present day primarily in tropical countries by commercial over-exploitation of tropical forest. At times, deforestation can be so extreme that it leads to [[desertification]], or the total loss of arable land, as has occurred in portions of the central highland plateau of [[Madagascar]] following extensive [[slash-and-burn]] activity.

A smaller, but important loss of arable land arises from the lack of renewal of rich flooding sediment due to flood control works. A large part of the arable land on earth is around the largest rivers on earth; for example, the [[Nile]] River, the [[Mississippi River]], the [[Tigris]] and [[Euphrates]] Rivers, the [[Yellow River]], the [[Amazon River]], the [[Ganges]] and the [[Rhine]] River.

The most productive portion of arable land is that from sediments left by those rivers and the sea in geological times. In modern times, the rivers do not generally flood as much agricultural land, due to the demands of [[flood control]] to support intensive agriculture required of a heavily-populated Earth.

The Nile continues to flood regularly, overspilling its banks. When the flood is over, the waters recede, leaving behind rich [[silt]]. This silt provides excellent fertilizer for [[Crop (agriculture)|crops]]. Even if the land is over-farmed and all the [[nutrient]]s are depleted from the soil, the land renews its fertility when new deposits of silt arrive following the next flood. Flood-control projects in the region, such as [[levee]]s, may increase human comfort but cause substantial adverse impact to the quantity and quality of arable land.

==Non-arable land==
[[Image:Arable land percent world.png|thumb|500px|Percentage of arable land by country, from [[CIA Factbook|CIA]] figures]]
Land which is unsuitable for arable farming usually has at least one of the following deficiencies: no source of fresh water; too hot (desert); too cold (Arctic); too rocky; too mountainous; too salty; too rainy; too snowy; too polluted; or too nutrient poor. Clouds may block the sunlight plants need for [[photosynthesis]] (making sunlight into food), reducing productivity. Plants can starve without light. [[Starvation]] and [[nomad]]ism often exists on marginally arable land. Non-arable land is sometimes called ''wasteland'', ''badlands'', ''worthless'' or ''no man's land''.

However, non-arable land can be converted into arable land. New arable land makes more food, and can reduce [[starvation]]. This outcome also makes a country more [[self-sufficient]] and politically independent, because food importation is reduced. Making non-arable land arable often involves digging new irrigation canals and new wells, aqueducts, [[desalination]] plants, planting trees for shade in the desert, [[hydroponic]]s, fertilizer, nitrogen fertilizer, [[pesticide]]s, [[reverse osmosis]] water processors, [[PET film (biaxially oriented)|PET film]] insulation or other insulation against heat and cold, digging ditches and hills for protection against the wind, and greenhouses with internal light and heat for protection against the cold outside and to provide light in cloudy areas. This process is often extremely expensive.

Some examples of infertile '''non-arable''' land being turned into fertile '''arable''' land are:
* [[Aran Islands]]: This island off the west coast of Ireland, (not to be confused with the [[Isle of Arran]] in [[Scotland]]'s [[Firth of Clyde]]), was unsuitable for arable farming because it was too rocky. The people covered the island with a shallow layer of seaweed and sand from the ocean. This made it arable. Today, crops are grown there.
* [[Israel]]: Israel's land primarily consisted of desert until the construction of [[desalination]] plants along the country's coast. The desalination plants, which remove the salt from ocean water, have created a new source of water for farming, drinking, and washing.
* [[Slash and burn]] agriculture uses nutrients in wood ash, but these expire within a few years.

Some examples of fertile '''arable''' land being turned into infertile land are:
* Droughts like the '[[dust bowl]]' of the [[Great Depression]] in the U.S. turned farmland into desert.
* [[Rainforest]] Deforestation: The fertile tropical forests turn into infertile desert land. For example, [[Madagascar]]'s central highland plateau has become virtually totally barren (about ten percent of the country), as a result of [[slash-and-burn]] deforestation, an element of [[shifting cultivation]] practiced by many natives.
* [[Roman Republic|Roman]]s' destruction of [[Carthage]]: At the end of the [[Punic War]]s, legend has it that the victorious Romans [[Salting the earth|sowed the earth with salt]], to symbolize total victory. The Roman symbol meant that Carthage would never grow back - their civilization ended. (Whether this actually happened is debatable due to the logistics involved. Salt was very valuable and was used as money at the time, and it would have taken a lot of salt to ruin the whole area. See [[Carthage#Roman Carthage|Carthage]] for details.) Most crops do not grow in highly saline soil. Consequently, salt water cannot be used to water crops.
* Each year, arable land is lost to desertification and [[erosion]] from human industrial activities. Improper irrigation of farm land can wick the [[sodium]], [[calcium]], and [[magnesium]] from the soil and water to the surface. This process steadily concentrates salt in the root zone, decreasing productivity for crops that are not salt-tolerant.
* [[Urban sprawl]]: In the United States, 8,900 km² (about 2.2 million acres) of land was added to urban areas between 1992 and 2002.

==References==
<references/>

== See also ==

*[[List of environment topics]]
*[[Fertility (soil)]]

==External links==
*[http://pages.prodigy.net/jhonig/bignum/qland2.html Surface Area of the Earth]

[[Category:Agricultural land]]

[[ar:صالحة للزراعة]]
[[es:Tierra arable]]
[[fr:Terre arable]]
[[is:Ræktarland]]
[[ja:農地]]
[[no:Dyrket mark]]
[[wa:Erûle tere]]
[[zh:耕地]]

Revision as of 18:33, 10 October 2008

October 2008

Welcome to Wikipedia. The recent edit you made to Flour has been reverted, as it appears to be unconstructive. Use the sandbox for testing; if you believe the edit was constructive, ensure that you provide an informative edit summary. You may also wish to read the introduction to editing. Thank you. Antonio Lopez (desu) 18:33, 10 October 2008 (UTC)