Industrial fixation is a synthetic method of converting atmospheric nitrogen to nitrogen oxides or ammonium ions that plants and other organisms are able to use. Fertilizer manufacturers use these processes in creating their products.
Manufacturers have three forms of industrial fixation from which to choose, the most common of which is the Haber or Haber-Bosch process. It involves heating nitrogen and hydrogen in a pressurized vessel with iron as a catalyst. The reaction produces ammonia, which is useful for plants and ultimately those organisms that consume them. A second option is the cyanamide process. The manufacturer heats calcium carbide in an atmosphere of pure nitrogen to form calcium cyanamide, a plant fertilizer. The third option is the electric arc process. The arc causes nitrogen and oxygen in the air to form oxides that bubble through water to form nitric acid.
Even though living organisms require nitrogen for life, most are unable to break the strong triple bond between two nitrogen atoms when the substance is in its elemental form. The element must be fixed to be metabolized.
Over 90 percent of the nitrogen fixation in the world occurs through the natural process of lightening and microorganisms known as diazotrophs. Examples of diazotrophs include bacteria and blue-green algae. Other diazotrophs exist in symbiosis with termites, plants and protozoa.