what is nitrogen cycle?
Answers
Answer:
Nitrogen Cycle
The nitrogen cycle is a biogeochemical cycle which explains the different chemical forms of nitrogen in the ecosystem. Nitrogen cycle begins with the atmospheric nitrogen which comprises 80% of the all gases in the atmosphere. The atmospheric nitrogen is fixed into the soil by lightning or nitrogen-fixing bacteria.
Ammonification
Nitrogen fixation can also be done by bacteria. There are two types of bacteria in an ecosystem: Symbiotic and non-symbiotic. Symbiotic bacteria such as Rhizobium, Anaebena-Azolla etc. converts the atmospheric nitrogen into ammonia (NH+4NH4+). The non-symbiotic bacteria such as Cyanobacteria also converts the atmospheric nitrogen to the ammonia.
Nitrification
However, the NH+4NH4+ has a positive charge and remains bound to the negatively charged clay. Thus, the NH+4NH4+ undergoes nitrification. There are two phases of nitrification i.e. nitrite and nitrate formation. In the first phase, the NH+4NH4+ is converted to NO−2NO2− by the bacteria Nitrosomonas. In the second phase, the NO−2NO2− is further oxidized to NO−3NO3− by another bacteria called Nitrobactor.
Denitrification
There are several bacteria which can utilize the NO−3NO3− and converts it to N2ON2O and N2N2. The examples of denitrifying bacteria are Pseudomonas, Paracoccus denitrificans etc.
NO−3NO3−→ N2ON2O→ N2N2
Assimilation
It is the process of uptake and integration of the nitrates and nitrites into the plant system.
The plants would store this nitrogen in the form of amino acids, DNA, RNA, proteins etc.
Decomposition:
When the plant dies, the microorganisms would degrade the organic matter and convert the nitrogen to ammonia. Hence ammonification again happens.
Answer:
The series of processes by which nitrogen and its compounds are interconverted in the environment and in living organisms, including nitrogen fixation and decomposition.