Nitrogen Cycle | Steps | Process & Diagram

By | March 26, 2020

Nitrogen Cycle

Nitrogen Cycle Definition:† it is basically continuous processes in which nitrogen moves from the atmosphere into the soil and into organisms and then moves back into the air or into soil†cyclicly. The whole process involved following processes such as nitrogen fixation, nitrification, decay, and denitrification.

Simple Nitrogen Cycle

  • On earth, all Living organisms entail Nitrogen Compounds like Protein and Nucleic acids for their life survival.
  • Atmosphere Air contains, 79% of Nitrogen gas (N2). Air†is the most important reservoir of nitrogen.
  • But the problematic situation is that most organisms cannot use Nitrogen in this N2 form.
  • Plants are able to secure Nitrogen is “fixed” or secure form by the process called Nitrogen Cycle.
  • Plants secure Nitrogen by incorporating these compounds such as Nitrate Ions (NO3?), Ammonium Ions (NH4+), Urea (NH2)2CO.
  • Animals secure their Nitrogen and all other compounds from plants or animals that have fed on plants. The Nitrogen Cycle Steps are described below.

Nitrogen Cycle Steps

Normally, The Nitrogen Cycle consists of four major steps. These four processes participate in the Cycling of Nitrogen through the whole Biosphere:

  1. Nitrogen fixation
  2. Decay
  3. Nitrification
  4. Denitrification

Nitrogen Cycle Process

  • The Nitrogen Cycle simply describes the procedure How Nitrogen Flows between Animals, Plants, Bacteria, Atmosphere, and Soil†on the Earth.
  • A most interesting fact about Nitrogen Cycle is that in the Atmosphere 78% Nitrogen gas is abundantly available but plants, as well as Animals, cannot use this directly.
  • Nitrogen element is an essential element that plays a vital role in the formation of Nucleic Acids and Amino Acids.
  • In addition, nitrogen is also the chief part of Adenosine Triphosphate Phosphate (ATP).
  • ATP is basically the topmost molecule of energy for all living organisms.
  • But Nitrogen is not directly taken up by plants and animals in the molecular form it should be converted into some other compounds.
Nitrogen Cycle Steps

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Nitrogen Cycle Explanation

Microorganisms play foremost roles in all four processes of the Nitrogen Cycle.

1. Nitrogen Fixation:

The Atmospheric Nitrogen molecules (N2) are relatively Inactive. In this step, these molecules are broken down. So, that its Nitrogen Atoms are able to combine with other Atoms and form many other Nitrogen-containing compounds. Nitrogen Fixation is the step that entails the input of Considerable Amounts of Energy. In the Biosphere three procedures are responsible for the Fixation of the Nitrogen Molecules:

  1. Atmospheric Fixation†
  2. Industrial Fixation
  3. Biological Fixation†

†i. Atmospheric Fixation

  • In the Atmospheric Fixation Fixing nitrogen is done by the Lightning Process.
  • In this Massive Energy of Lightning breakdowns, the Atmospheric Nitrogen Molecules. And empowers their Atoms to combine with Oxygen.
  • Due to this Nitrogen Oxide is formed. These Nitrogen Oxides are dissolving in Rain. And form Nitrates.
  • Furtherly, they come on Earth. Atmospheric Nitrogen Fixationpossibly contributes 5Ė 8% of the total Nitrogen Fixation.

ii. Industrial Fixation:

  • In the Industrial Nitrogen Fixation, Atmospheric Nitrogen Molecules are treated with High Pressure at 600įC Temperature.
  • In the Industrial Nitrogen Fixation, Catalyst is used due to which atmospheric Nitrogen and Hydrogen mutually combined and Ammonia (NH3) is formed.
  • In this process, Hydrogen gas is consequentially formed from Natural Gas or Petroleum.
  • Ammonia that is formed from Industrial Nitrogen Fixation can be used directly as Fertilizer.
  • But mostly it is utilized to administered Urea and Ammonium Nitrate (NH4NO3).

iii. Biological Fixation:

  • In Biological Fixation certain microorganisms are used.
  • Microbes alone or in a Symbiotic Relationship with some plants and animals help in the Fixation of Nitrogen molecules.
  • Many Bacteria and Archaea have the capability to Fix Atmospheric Nitrogen Molecules.
  • Biological Nitrogen Fixation can be done by two procedures:
  1. Symbiotic nitrogen fixation
  2. Symbiotic nitrogen fixation

a) A-Symbiotic Nitrogen Fixation:

This type of nitrogen fixation is not advantageous for plants. A-Symbiotic Nitrogen Fixation is done by the following Microorganisms:

Aerobic Bacteria: †Aerobic Bacteria are those Bacteria that donít necessitate Oxygen to fix Nitrogen. e.g.:† Azotobactor

Anaerobic bacteria: †Anaerobic Bacteria are those Bacteria that require Oxygen to fix Nitrogen. e.g:† Clostridium

Blue-green algae or Cyanobacteria:†They are those bacteria that befalls in Water Logs and Paddy Fields and fixes nitrogen.

b) Symbiotic Nitrogen Fixation:

This type of Nitrogen Fixation is advantageous for plants. Symbiotic Nitrogen Fixation is done by the following Microorganisms:

Fungi: They are Biological Nitrogen Fixers whose group Actinomycetes fixes Nitrogen abundantly. e.g: Casurina in Pinus fixes the Nitrogen. Biological Nitrogen Fixation entails a composite set of enzymes and enormous spending of ATP.

Moreover, the first, stable merchandise product of this process is Ammonia is produced which is rapidly combined and form Protein and other Organic Nitrogen Compounds.

2. Decay:

The proteins that the plants made enter and permit throughout the Food Webs. Like the Carbohydrates do. At each Trophic level, the breakdown of the organic Nitrogen Compound that excretes nitrogenous compounds returns to the environment. The final recipients of these materials are microorganisms of decay. Micro-organisms break down the molecules into Ammonia.

3. Nitrification

Ammonia is the compound that is taken up by plants directly. Mostly with the help of Roots. Foremost, Ammonia that is produced by Decay is then Converted into Nitrates. While Nitrification whole process is completed into two steps:

In the First Step, Bacteria Nitrosomonasoxidize NH3† into††Nitrites†(NO2?).

In the Second step, Bacteria†Nitrobacter†oxidizes the Nitrites into†Nitrates†(NO3?). These two bacteria are Autotrophic bacteria and known as Nitrifying Bacteria.

4. Denitrification:

Denitrification is the process in which the reduction of Nitrates and Nitrites into nitrogen gas is done. This is basically the reverse process of Nitrification. Due to this step Nitrogen gas, restocked in the Atmosphere. During the Denitrification following intermediates, compounds are formed: For Example Nitric Oxide (NO), Nitrous Oxide (N2O), Nitrous Acid (HONO)

Nitrogen Cycle Diagram

Nitrogen Cycle Diagram