Nitrogen is an element that is essential for many biological processes and is crucial for life on Earth. Although the Earth's atmosphere is an abundant source of nitrogen, most of it is unusable by plants and animals.The transformation of nitrogen into different compounds that can be used by plants and animals is carried out through different stages. This is known as the nitrogen cycle.
Ammonification
In this stage, atmospheric nitrogen is converted into usable form - ammonia (NH3) by 3 different types of processes.1. Biological Fixation (bacteria like Rhizobium and blue-green algae that transform unusable nitrogen to readily visible components that get fixed in the soil)
Nitrification
2. Atmospheric Fixation (energy of lightning breaks down nitrogen into oxides used by plants)3. Industrial Fixation (nitrogen is converted into ammonia and chemical fertilizers by artificial processes in industries and factories)
Denitrification
Nitrogen
(NH3)
When plants/animals die, nitrogen present in the organic matter is released back into the soil.Decomposers like bacteria and fungi present in the soil convert organic matter back into ammonium
Nitrogen
Decomposers(bacteria, fungi)
Ammonia
Ammonia is converted into nitrates and then into nitrates by bacteria like Nitrobacter in the presence of oxygen in the soil.
Ammonia
with presence of oxygen
(Nitrobacter)
Nitrates
Nitrites
Nitrates are converted into gaseous nitrogen. Catried out by denitrifying bacteria like Pseudomonas in the absence of oxygen.