nitrogen fixation

American  

noun

1. any process of combining atmospheric nitrogen with other elements, either by chemical means or by bacterial action: used chiefly in the preparation of fertilizers, industrial products, etc.

2. this process as performed by certain bacteria found in the nodules of leguminous plants, which make the resulting nitrogenous compounds available to their host plants.

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nitrogen fixation British  

noun

1. the conversion of atmospheric nitrogen into nitrogen compounds by certain bacteria, such as Rhizobium in the root nodules of legumes

2. a process, such as the Haber process, in which atmospheric nitrogen is converted into a nitrogen compound, used esp for the manufacture of fertilizer

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nitrogen fixation Scientific  

1. The process by which free nitrogen from the air is combined with other elements to form inorganic compounds, such as ammonium ions, which can then be converted by nitrification into nutrients that can be readily absorbed by plants and other organisms for incorporation into more complex organic compounds. During lighting strikes, the atmosphere's free nitrogen molecules (N ₂) are broken apart and combine with oxygen to form nitrogen oxides that dissolve in rain to form nitric acid; atmospheric nitrogen is also fixed industrially under high pressure and heat to form ammonia, as in the production of fertilizers. Many species of cyanobacteria and certain other forms of bacteria, especially those that live in the roots of legumes, conduct nitrogen fixation as part of their metabolism, using the enzyme nitrogenase to combine nitrogen with hydrogen as ammonia. All living organisms are dependent on nitrogen fixation and would ultimately die without it.

2. See more at nitrogen cycle

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Other Word Forms

• nitrogen-fixing adjective

Etymology

Origin of nitrogen fixation

First recorded in 1890–95

Example Sentences

"We compared different Earth System models with current nitrogen fixation values and found that they overestimate the nitrogen fixation rate on natural surfaces by about 50 percent," Weber explains.

From Science Daily • Jan. 5, 2026

"It is quite remarkable that we are now able to take a receptor from barley, make small changes in it, and then nitrogen fixation works again," says Kasper Røjkjær Andersen.

From Science Daily • Dec. 9, 2025

During nitrogen fixation, bacteria reduce the ratio of the stable nitrogen isotopes 15N to 14N in seawater.

From Science Daily • Nov. 19, 2025

To confirm the meaning of these chemical signatures, seawater samples collected by the research vessel Eugen Seibold were used to calibrate the nitrogen isotopes in modern corals, demonstrating that they reliably record nitrogen fixation.

From Science Daily • Nov. 19, 2025

That they have come ultimately from the free atmospheric nitrogen seems certain, and various attempts have been made to explain a method of this nitrogen fixation.

From The Story of Germ Life by Conn, H. W. (Herbert William)