Nitrogen Cycle Meaning

What is Nitrogen Cycle:

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

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

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

It should be noted that Nitrogen is the most abundant chemical element in the atmosphere. and a basic element for living beings because it makes it possible to make amino acids, DNA and proteins.

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

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

See also the meaning of Nitrogen and Biogeochemical Cycles.

Nitrogen Cycle Process

Cycle of nitrogen

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.

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Biological fixation

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

Nitrogen reaches the earth by the energy released from lightning that is released from electrical storms by sending nitrogen back to the ground through precipitation.

Food chain

Nitrogen enters the food chain once vegetables and plants obtain it from the soil; from there it passes to herbivorous animals and from these to carnivores.


It refers to the chemical transformation of the 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 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 (by dissolving 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, excessive fertilization of the soil, felling of trees, intensive cultivation, thermal power plants, or vehicle fuel significantly affect this cycle because it affects nitrogen levels in the natural state and generates higher levels of pollution.

See also the meaning of Carbon Cycle and Sulfur Cycle.