The conversion of atmospheric nitrogen
This is the process of conversion of ammonia -- nitrites -- nitrates.
All the nitrites and nitrates produced are consumed by plants and animals. The nitrites and nitrates transfer into their body.
This is where the decomposing bacteria converts the waste, which are rich in nitrogen, into simpler compounds.
This is the last step of the nitrogen cycle. This is when bacteria converts nitrogen compounds into nitrogen gas and returns it into the atmosphere.