Explain and illustrate nitrogen cycle.

Explanation

The nitrogen cycle is biogeochemical cycle by which nitrogen is converted into various chemical forms as it circulates among the atmosphere, terrestrial and marine ecosystems.
Certain bacteria and blue-green algae present in the soil fix nitrogen from the atmosphere and convert it into compounds of nitrogen. It can be utilised by plants from the soil through their root system. Nitrogen is then used for synthesis of plant proteins and other compounds. Animals feeding plants get these proteins and other nitrogen compounds.
When plants and animals die, bacteria and fungi present in the soil convert nitrogenous wastes into nitrogenous compounds to be used by plants again. Certain other bacteria convert some part of them to nitrogen gas which goes back into the atmosphere. This completes the nitrogen cycle due to which the concentration of nitrogen in the atmosphere almost remains constant.