what is nitrogen cycle????

Dear Student

Nitrogen Cycle: 

Nitrogen is an important constituent of tissues, enzymes, proteins, nucleic acids and amino acids. Atmosphere contains about 78% of nitrogen and it cannot be used by plants and animals as molecular nitrogen. It is an essential nutrient for all life forms and the perfect nitrogen cycle in biosphere involves the important steps named, Nitrogen fixation, Ammonification, Nitrification and Denitrification.

  • Nitrogen fixation: The atmospheric nitrogen converts into nitrites by microbes like Rhizobium, blue green algae and azotobactor.
  • Ammonification:Decomposition of dead organic matter into ammonia by fungi and decay bacteria.
  • Nitrification: Ammonia becomes nitrites and then to nitrates by nitrosomonas and nitrobactor.
  • Denitrification: Nitrites in the soil release atmospheric nitrogen by pseudomonas.


Thus, nitrogen cycle in nature passes nitrogen from its elemental form in the atmosphere into simple molecules into soil and water, which get converted into more complex molecules in living beings and back again into simple nitrogen molecule in the atmosphere. That’s why Nitrogen cycle is called as perfect cycle.


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