Nitrogen fixation is a process by which nitrogen in the Earths atmosphereis covered into ammonia or other molecules available to living organisms. Atmospheric nitrogen or molecular dinitrogen is relatively inert, it does not easily react with other chemicals to form new compounds.

Nitrogen can be fixed by converting nitrogen and oxygen into NOx nitrogen oxides , if there is oxygen in the air. NOx may react with water to make nitric acids which seeps into soil, where it makes nitrate, whuch is of use to growing plants.