- Nitrogen forms 78% i.e. the maximum portion of the atmosphere. It is necessary for the maintenance of the cycle of nature.
- The circulation and recycling of nitrogen gas into the form of different compounds through various biotic and abiotic processes in nature is called the nitrogen cycle.
- All organisms participate in the nitrogen cycle. It is an important component of proteins and nucleic acids.
- As compared to other elements, it is inactive and does not easily combine with other elements. Most organisms cannot use the free form of nitrogen.
- Important processes of nitrogen cycle:
(a) Nitrogen fixation: Conversion of nitrogen into nitrates and nitrites through atmosphere, industrial and biological processes.
(b) Ammonification: Release of ammonia through the decomposition of dead bodies and excretory wastes of organisms.
(c) Nitrification: Conversion of ammonia into a nitrite and then nitrate.
(d) Denitrification: Conversion of nitrogen compounds into gaseous nitrogen.
