Green manure

Green manure

In agriculture, a green manure is a type of cover crop grown primarily to add nutrients and organic matter to the soil. Typically, a green manure crop is grown for a specific period, and then plowed 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-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 for pollinating insects.

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 oats or rye have long been used as green manures.
*Fava beans
*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.

ee also

*Fertilizer
*Organic gardening
*

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]


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Look at other dictionaries:

  • green manure — n. 1. a crop of plants, as clover, plowed under while still green to fertilize the soil 2. fresh manure …   English World dictionary

  • green manure — green′ manure′ n. 1) agr. a crop of growing plants, as clover and other nitrogen fixing plants, plowed under to enrich the soil 2) manure that has not undergone decay • Etymology: 1835–45 …   From formal English to slang

  • green manure — noun a growing crop that is plowed under to enrich soil • Hypernyms: ↑manure * * * ˌgreen maˈnure f13 [green manure] noun uncountable …   Useful english dictionary

  • green manure — noun Date: 1842 an herbaceous crop (as clover) plowed under while green to enrich the soil • green manure transitive verb …   New Collegiate Dictionary

  • green-manure — transitive verb see green manure …   New Collegiate Dictionary

  • green-manure — | ̷ ̷ ̷ ̷| ̷ ̷ transitive verb : to fertilize with green manure …   Useful english dictionary

  • green-manure crop — noun see green manure …   Useful english dictionary

  • green manure — /grin məˈnjuə/ (say green muh nyoohuh) noun 1. a green crop, especially clover and other nitrogen fixing plants, ploughed into the soil for fertiliser. 2. manure which has not undergone decay …  

  • green manure — Agric. 1. a crop of growing plants, as clover and other nitrogen fixing plants, plowed under to enrich the soil. 2. manure that has not undergone decay. [1835 45] * * * Crop grown and plowed under for its beneficial effects to the soil and… …   Universalium

  • green manure — plants grown for ploughing into the bed of s dried up pond as fertiliser for when the pond is refilled …   Dictionary of ichthyology

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