Nitrification - Nitrification is the biological oxidation of ammonia or ammonium to nitrite followed by the oxidation of the nitrite to nitrate.....
Denitrification - Denitrification is a microbially facilitated process where nitrate is reduced and ultimately produces molecular nitrogen through a series of intermediate gaseous nitrogen oxide products.....
Ammonification - Ammonification is the process by which the organically bound nitrogen of microbial, plant, and animal biomass is recycled after their death.....

Nitrification:

Nitrification is an essential biological process in the nitrogen cycle, where ammonia is converted into nitrate. It occurs in two sequential steps performed by specific groups of microorganisms.

Step 1: Ammonia Oxidation (Nitrosation)
- Ammonia-oxidizing bacteria (AOB) convert ammonia (NH3) to nitrite (NO2-) through the process of ammonium oxidation or nitrosation.
- The primary group of AOB responsible for this step is Nitrosomonas.
- This step is an aerobic process, meaning it requires oxygen for bacteria to function.

Step 2: Nitrite Oxidation (Nitration)
- Nitrite-oxidizing bacteria (NOB) convert nitrite (NO2-) to nitrate (NO3-) through the process of nitrite oxidation or nitration.
- The primary group of NOB responsible for this step is Nitrobacter.
- This step is also an aerobic process.

Dentrification:

Dentrification is a microbial process that occurs in anaerobic conditions and involves the conversion of nitrate (NO3-) back into nitrogen gas (N2). It completes the nitrogen cycle by removing excess nitrogen from ecosystems.

Step 1: Nitrate Reduction
- In the absence of oxygen, denitrifying bacteria convert nitrate (NO3-) into nitrite (NO2-), and further reduce it to nitric oxide (NO), nitrous oxide (N2O), and eventually, nitrogen gas (N2).
- The primary group of denitrifying bacteria responsible for this step is Pseudomonas and Paracoccus.

Step 2: Nitrogen Gas Production
- Finally, the produced nitrogen gas (N2) is released into the atmosphere, completing the denitrification process.
- This step is crucial in maintaining a balanced nitrogen cycle and preventing excessive nitrogen accumulation in ecosystems.

Ammonification:

Ammonification is the process by which organic nitrogen is converted into ammonia (NH3) by bacteria and fungi. It is a crucial step in the decomposition of nitrogen-rich organic matter, such as dead plants and animals, into inorganic forms that can be utilized by other organisms.

- Organic Nitrogen Decomposition:
- Bacteria and fungi decompose organic matter, breaking down proteins and other nitrogen-containing compounds.
- This decomposition releases organic nitrogen in the form of amino acids, urea, and other nitrogen-rich compounds.

- Ammonia Production:
- Ammonifying bacteria, such as Bacillus and Clostridium, convert organic nitrogen compounds into ammonia (NH3).
- This ammonia can be further utilized by nitrifying bacteria in the nitrification process or directly taken up by plants for growth.

Ammonification plays a vital role in the nitrogen cycle as it recycles organic nitrogen from dead organisms and waste materials, making it available for use by living organisms.