Nitrogen cycle meaning

What is Nitrogen Cycle:

Each of the biological processes (of plants, animals and microorganisms) and abiotic processes (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 by living beings (animals and plants), as well as by air, water or land.

For this reason, the nitrogen cycle is one of the most important biogeochemical cycles for maintaining the balance of the terrestrial biosphere.

It should be noted that nitrogen is the most abundant chemical element in the atmosphere and a basic element for living beings because it allows the elaboration 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 nitrogen to be absorbed by living beings, plants and bacteria that are responsible for fixing nitrogen must intervene to incorporate it into the soil so that it can be used by animals and plants before it becomes nitrogen gas and return to atmosphere.

See also the meaning of Nitrogen and Biogeochemical Cycles.

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 by means of symbiotic bacteria that live in plants and absorb the nitrogen obtained by the soil.

Nitrogen reaches the earth through the energy released from the lightning strikes that are released from electrical storms by sending the 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 goes to herbivorous animals 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 ammonia nitrogen.

Nitrification and denitrification

In this process, ammonia 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 (by dissolving in water) and reaching lakes and rivers.

Nitrogen cycle and human activity

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

For example, over-fertilizing the soils, cutting down trees, intensive cultivation, thermal power plants or vehicle fuel significantly affect this cycle because it affects nitrogen levels in their natural state and generates higher levels of pollution.

Tags:  Expressions-In-English Science Expressions-Popular