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

Building on those results, a new analysis shows that the way nitrogen fixation is calculated in some Earth System models has now been reassessed.

From Science Daily • Jan. 5, 2026

When corals display low 15N to 14N ratios, it signals periods of increased nitrogen fixation.

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

The team linked algae growth, enhanced nitrogen fixation, and the upwelling of cool, nutrient-rich waters by studying coral cores collected across the Caribbean.

From Science Daily • Nov. 19, 2025

It may be, however, that as the nitrogen fixation enterprise was developed there, requiring a large amount of technical development and control, this was considered a sufficient contribution to the general cause.

From The Riddle of the Rhine; chemical strategy in peace and war by Lefebure, Victor