Nitrogen fixation

Nitrogen fixation is a process by which nitrogen in the air is converted into ammonia  (NH3) or related nitrogenous compounds. Biological nitrogen fixation converts N2 into ammonia, which is metabolized by most organisms. Nitrogen fixation is essential for life because fixed inorganic nitrogen compounds are required for the biosynthesis of all nitrogen-containing organic compounds, such as amino acids and proteins. As part of the nitrogen cycle, it is essential for agriculture and the manufacture of fertilizer. It is also, indirectly, relevant to the manufacture of all chemical compounds that contain nitrogen, which includes explosives, most pharmaceuticals, and dyes. Nitrogen fixation is carried out naturally in the soil by a wide range of microorganisms.Nitrogen fixation also occurs between some termites and fungi. It also occurs naturally in the air by means of NOx  production by lightning. All biological nitrogen fixation is effected by enzymes called nitrogenases. These enzymes contain iron.


Reference https://en.m.wikipedia.org/wiki/Nitrogen_fixation