Nitrogen fixation

Nitrogen fixation is a process in which nitrogen (N₂) in the atmosphere is converted into ammonium (NH₄⁺) or nitrogen dioxide (NO
2), for example. Atmospheric nitrogen or molecular nitrogen (N₂) is relatively inert: it does not easily react with other chemicals to form new compounds. The fixation process frees up the nitrogen atoms from their triply bonded diatomic form, N≡N, to be used in other ways.

Nitrogen fixation, natural and synthetic, is essential for all forms of life because nitrogen is required to biosynthesize basic building blocks of plants, animals and other life forms, e.g., nucleotides for DNA and RNA and amino acids for proteins. Therefore, as part of the nitrogen cycle, it is essential for agriculture and the manufacture of fertilizer. It is also an important process in the manufacture of explosives (e.g. gunpowder, dynamite, TNT, etc.). Nitrogen fixation occurs naturally in the soil with the help of some types of bacteria and plants (for example, Azotobacter and legumes). It also occurs naturally in the air by means of lightning.