| Nitrification | De-nitrification |
| The process of conversion of ammonia into nitrates and nitrites is called Nitrification. | The process of conversion of nitrates and nitrites into atmospheric nitrogen(N2) is called denitrification. |
| This process is done mostly by nitrifying bacteria under aerobic conditions. | This is done with the help of denitrifying bacteria under anaerobic conditions. |
| The precursor in this process is ammonia while the end product is nitrates and nitrites. | Here is the precursors are nitrates and nitrites while the end product is atmospheric nitrogen. |
| This process is useful to plants for nitrogen fixation because they cannot absorb free nitrogen from the atmosphere. | This process has its application in wastewater treatment plants and is beneficial for aquatic life. |
| Nitrobacter, Nitrosomonas are some examples of nitrifying bacteria. | Pseudomonas, Thiobacillus are some examples of denitrifying bacteria. |
