Explanation:
It is the process of converting free nitrogen into nitrogenous compounds .
Let us study about it :
In nature there are certain plants called as leguminous plants .These plants have nitrogen fixing bacteria called as rhizobium in their root nodules .
This bacteria can convert free atmospheric nitrogen into ammonia .
Then this ammonia with the help of bacteria nitrosomonas and nitrobacter gets converted into nitrites and nitrates .
Then these nitrites and nitrates with the help of bacteria like pseudomonas gets converted back into free nitrogen ,
This cycle helps in enriching the soil and to maintain nitrogen percent constant in atmosphere ,
The biogeochemical cycle : for nitrogen is attached below
