What is Green manure?
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 several functions, that include soil improvement and soil protection: * Leguminous green manures such as [[clover]] 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 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. *[[Mustard plant|Mustard]] *[[Clover]] *[[Fenugreek]] *[[Lupin]] *Sunn hemp *Winter tares *Winter field beans *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, such as the addition of [[animal]] manures. If animal manures are not available, in a stockless rotation, green manures perform a vital function