The Nitrogen fixation reference article from the English Wikipedia on 24-Apr-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Nitrogen fixation

Nitrogen fixation is the process by which nitrogen is taken from its relatively inert molecular form (N₂) in the atmosphere and converted into nitrogen compounds useful for other chemical processes (such as, notably, ammonia, nitrate and nitrogen dioxide).

Nitrogen fixation is performed naturally by a number of different protists, including bacteria, actinomycetes and cyanobacteria. certain types of anaerobic bacteria. Many higher plants have formed associations with these microorganisms. The best known are legumess such as clover which contain symbiotic bacteria within nodules in their root systems, producing nitrogen compounds that help to fertilize the soil. Plants from many other families have similar associations, such as alder, Ceanothus, Azolla, and Casuarina. Certain lichens also contain nitrogen fixing cyanobacteria.

Nitrogen can also be artificially fixed for use as fertilizer or in other industrial processes. The most popular method is by the Haber process. Artificial fertilizer production has achieved such scale that it is now the largest source of fixed nitrogen in the Earth's ecosystem.

Table of contents

1 Non-leguminous N-fixing plants 2 See also 3 External links

Non-leguminous N-fixing plants

• Lobaria pulmonaria lichen
• cycads
• Gunnera
• Red alder
• Snowbrush (Ceanothus velutinus)
• Wax myrtle (Myrica californica)
• Mountain-mahogany (Cercocarpus ledifolius)
• Bitterbrush (Purshia tridentata)
• Buffalo berry (Shepherdia argentea)
• Beefwood (Casuarina equisetifolia)

See also

• Nitrogen deficiency
• Nitrogen cycle
• George Washington Carver

External links

• Nitrogen Fixation

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