What is the last stage of the nitrogen cycle?

Denitrification is the last stage of the nitrogen cycle. Nitrate present in the soil is also reduced to nitrogen by the process of denitrification. This process is carried out by the denitrifying bacterial species- Clostridium and Pseudomonas, which will process nitrate to gain oxygen and gives out free nitrogen gas as a byproduct.

Further Reading:

• The Nitrogen Cycle
• Geography Notes