Question

explain nitrogen cycle in your own word
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Answer 1

The nitrogen cycle involves conversion of Nitrogen from its elemental form in the atmosphere into simpler molecules in the soil and water. These further get converted into more complex molecules in living beings. Finally, the complex molecules are reduced and released back into the atmosphere as simple Nitrogen molecules.

Nitrogen that occurs as an inert molecule in the atomsphere is split or converted to Nitrates through physical process like lightening, the Nitrogen atoms react with rain water molecules to form compounds and through biochemical process by micro-organisms.

Fixing of atmospheric nitrogen by micro-organisms takes place in following steps:

1. Nitrogen fixation : It is the process wherein atmospheric nitrogen is converted into water-soluble nitrates. This step is performed by organisms like Rhizobium, Azotobacter and blue-green algae.
2. Nitrification : It is the process in which ammonia is first converted into nitrites and then into nitrates. This step is performed by nitrifying bacteria like Nitrosomonas and Nitrobacter.
3. Ammonification : It is process in which complex, dead organic matter is decomposed into ammonia. This step is performed by organisms like decay bacteria and fungi. Organic nitrogen compounds
4. Assimilation : In this step, NH3, NO3 are incorporated into the biological tissues.
5. Dentrification : It is the process wherein the nitrates present in the soil are reduced to release nitrogen back into the atmosphere.