The nitrogen cycle is crucial to the survival of living beings and organisms. Nitrogen is necessary for healthy plant growth and seed development. About 78% of the gas in the air is nitrogen. Still, atmospheric nitrogen is not helpful to organisms in its gaseous form. It becomes useful when nitrogen-fixing bacteria transform it.

There are various steps in the nitrogen cycle. These steps are: 

Nitrogen fixation
Nitrogen assimilation 
Ammonification
Nitrification
Denitrification 
Nitrogen fixation is the process of converting atmospheric nitrogen into ammonia. Ammonia then becomes ammonium, which enters the soil and water reservoirs. The two types of nitrogen-fixing bacteria are non-symbiotic bacteria and symbiotic bacteria. The non-symbiotic bacteria are cyanobacteria, nostoc, and azotobacter. In contrast, the mutualistic bacteria include rhizobium, a bacteria common to leguminous plants.

The bacteria enter the root hairs of host plants, multiply, and influence the formation of root nodules. They enlarge plant cells and bacteria in close association. They convert atmospheric nitrogen to ammonia, which the plant uses for development. 

Nitrates and ammonia from nitrogen fixation assimilate into tissue compounds of algae and higher plants, which animals eat. After assimilation, the animals convert them to the mineral nutrients they need. Ammonification begins by decomposing living organisms and their waste products.

Depending on the soil conditions, the ammonia produced can leave the soil or be changed into other nitrogen compounds. Nitrification is converting ammonia in soil into nitrates by nitrifying bacteria. At the same time, denitrification is the process of denitrifying bacteria and metabolizing bacteria. 

The denitrifying bacteria is more active in water-logged areas. It breaks down nitrates in the soils, converting them to atmospheric nitrogen. The nitrogen cycle is a never-ending process of nitrogen conversion that sustains life and the food chain.