What are the Meanings of Nitrogen Cycle?

What is Nitrogen Cycle?

Each of the biological processes (of plants, animals and microorganisms) and abiotic (of light, pH, soil characteristics, among others) on which the supply of this element in living beings is based, is called the nitrogen cycle. .

Nitrogen is a chemical element that moves slowly through a cycle through which it can be absorbed both by living things (animals and plants), and by air, water or land.

Therefore, the nitrogen cycle is one of the most important biogeochemical cycles to maintain the balance of the terrestrial biosphere .

It should be noted that nitrogen is the chemical element with the greatest abundance in the atmosphere and a basic element for living beings because it allows the production of amino acids, DNA and proteins.

However, a good percentage of living beings cannot take advantage of it without having completed the cycle, except for specialized microorganisms, such as algae or bacteria.

Consequently, for the nitrogen to be absorbed by living beings, the plants and bacteria that are responsible for fixing the nitrogen to incorporate it into the soil must intervene so that it can be used by animals and plants before it becomes gaseous nitrogen and return to the atmosphere.

Nitrogen cycle process

The nitrogen cycle consists of several processes that must be carried out so that nitrogen can be used by living beings.

For this reason, the nitrogen cycle develops after a well-defined process of steps, which includes physical, chemical and biological processes.

Biological fixation

Living beings cannot absorb nitrogen in the gaseous state as it is found in the atmosphere, so it must be transformed into organic nitrogen, which is achieved through biological fixation through symbiotic bacteria that live in plants and absorb the nitrogen obtained by the soil.

Nitrogen reaches the earth by energy released from lightning strikes from thunderstorms by sending nitrogen back into the ground through precipitation.

Food chain

Nitrogen enters the food chain once vegetables and plants obtain it from the soil; from there it goes to herbivores and from these to carnivores.


It refers to the chemical transformation of nitrogen that was consumed and absorbed by plants and animals, which once dead decompose and release ammoniacal nitrogen.

Nitrification and denitrification

In this process, ammoniacal nitrogen is once again contained in the soil and is used by plants as nitric nitrogen (nitrification).

However, these nitrates can return to the atmosphere through denitrification (when nitrate is reduced to nitrogen gas) or by leaching (when dissolved in water) and reach lakes and rivers.

Nitrogen cycle and human activity

There are various human activities that negatively affect the nitrogen cycle.

For example, overfertilizing soils, cutting down trees, intensive cultivation, thermal power plants or vehicle fuel significantly affect this cycle because it affects natural nitrogen levels and generates higher levels of contamination.

What is Nitrogen Cycle