Nitrogen CycleAtmospheric gas constitutes 78% of nitrogen along with other gases. Nitrogen forms the major constituent of protein, nucleic acids, chlorophyll and vitamins. Nitrogen cycle is the biogeochemical cycle that describes the transformation of nitrogen and nitrogen-containing compounds in nature.
Nitrogen cycle includes the following steps as follows :
- Plants cannot absorb the atmospheric nitrogen. Lightning (abiotic factor) brings atmospheric nitrogen to soil or some bacteria or blue green algae (biotic factor) convert the atmospheric nitrogen into nitrogenous compounds in the soil.
- Most of the plants absorb the nitrogen from the soil in the form of nitrates. They convert it into plant proteins. When the animals (herbivores) feed on the plants, nitrogen gets into the protein diet of animals.
- When the plants and animals die, the nitrogenous waste added to the soil is acted upon by the decomposers like bacteria and fungi and very soon it is converted into nitrogenous compounds.
- Certain other group of bacteria acts on the nitrogenous compounds and convert them into free nitrogen which escapes back into the atmosphere.
- Thus, nitrogen cycle makes more or less constant percentage of nitrogen in the atmosphere.