Green manure
409255
212377098
2008-05-14T16:09:47Z
Bhadani
219828
Reverted edits by [[Special:Contributions/63.144.4.45|63.144.4.45]] ([[User talk:63.144.4.45|talk]]) to last version by 86.139.91.3
In [[agriculture]], a '''green manure''' is a type of [[cover crop]] grown primarily to add [[nutrient]]s and [[organic matter]] to the [[soil]]. Typically, a green manure crop is grown for a specific period, and then [[plow]]ed under and incorporated into the soil. Green manures usually perform multiple functions, that include soil improvement and soil protection:
* [[Leguminous]] green manures such as [[clover]] and [[vetch]] contain [[Nitrogen fixation|nitrogen-fixing]] [[symbiotic]] [[bacteria]] in [[root nodules]] that fix atmospheric nitrogen in a form that plants can use.
* Green manures increase the percentage of organic matter ([[biomass]]) in the soil, thereby improving [[water]] retention, aeration, and other soil characteristics.
*The [[root]] systems of some varieties of green manure grow deep in the soil and bring up nutrient resources unavailable to shallower-rooted crops.
* Common cover crop functions of [[weed]] suppression and prevention of soil [[erosion]] and compaction are often also taken into account when selecting and using green manures.
*Some green manure crops, when allowed to [[flower]], provide [[Forage (honeybee)|forage]] for pollinating [[insect]]s.
Historically, the practice of green manuring can be traced back to the [[fallow]] cycle of [[crop rotation]], which was used to allow soils to recover.
==Green manure crops==
*Winter cover crops such as [[oat]]s or [[rye]] have long been used as green manures.
*[[Fava beans]]
*[[Mustard plant|Mustard]]
*[[Clover]]
*[[Fenugreek]]
*[[Lupin]]
*[[Sunn hemp]], a tropical legume
*Vetch or [[Winter tares]], including fava beans.
*[[Winter field beans]]
*[[Alfalfa]], which sends roots deep to bring nutrients to the surface.
*[[Tyfon]], a ''Brassica'' known for a strong tap root that breaks up heavy soils.
*[[Buckwheat]] is a rapidly growing green manure in temperate regions.
*Ferns of the genus ''[[Azolla]]'' have been used as a green manure in southeast [[Asia]].
*[[Velvet bean]] (Mucuna pruriens) Common in the southern US during the early part of the 20th century, before being replaced by soybeans. Popular today in most tropical countries, especially in Central America where it is the main green manure used in Slash/Mulch farming practices.
==Green manures in organic farming==
[[Organic farming]] relies on soil [[health]] and cycling of nutrients through the soil using natural processes. Green manures perform the vital function of fertilization, in concert with the addition of [[animal]] manures if those are used.
==See also==
*[[Fertilizer]]
*[[Organic gardening]]
*[[:Category:Soil improvers]]
==External links==
*[http://www.attra.org/attra-pub/covercrop.html Overview of cover crops and green manures]
*[http://www.organicfarmingworld.com/greenmanuring.html Methods of Green Manuring]
*Using green manure to grow rice [http://www.irri.org/donors/SDC/pdfs/NutMgmtRnfedLwlndRiceLaoPDR.pdf]
*[http://www.sarep.ucdavis.edu/ccrop/ University of California cover crops database]
[[Category:Crops]]
[[Category:Agriculture]]
[[Category:Sustainable technologies]]
[[Category:Soil improvers]]
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[[simple:Green manure]]