Nitrogen fixation

1888 Nitrogen fixation

The book of science

Tom Sharp

Hermann Hellriegel botany

Nitrogen fixation

Mysterious biology

Natural efficiency

Earth’s atmosphere is 78.09% nitrogen in its diatomic form (N2), in which pairs of nitrogen atoms are joined by an extremely strong bond. All living organisms require nitrogen in their DNA and RNA; all green plants require nitrogen as a primary nutrient. About 3% of the human body is nitrogen.

After diatomic nitrogen is broken, it can be combined with other elements into many useful forms, including ammonia (NH3), nitrate (NO3) used for artificial fertilizers, nitric acid (HNO3), nitroglycerin used for explosives such as dynamite, and cyanides (which include a nitrogen atom triple-bonded to a carbon). When these compounds decompose back to nitrogen gas, they release large amounts of energy, and can, therefore, explode.

Rhizobia are not the only miracles of nature that fix nitrogen. Some non-legumes have nitrogen-fixing symbiotic associations with cyanobacteria or Frankia bacteria. All natural nitrogen-fixing processes use an enzyme complex named nitrogenase. Also, there are industrial processes to create ammonia and other nitrogen compounds including a process based on a method used by Henry Cavendish in 1784.

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