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Nitrogen Fixation

Nitrogen fixation is the process by which elemental nitrogen is converted into other nitrogen compounds which are useful for chemical processes. Nitrogen is fixed in two ways: one during lightning and by nitrogen fixing bacteria, and blue- green algae.

Rhizobium bacteria: -
Rhizobium bacteria living in the root nodules of legume plants, fix nitrogen from the
atmosphere. Microorganisms in the soil convert atmospheric nitrogen into ammonium
compounds, thereby enabling the survival of plants and animals.

What is the mechanism of each of these steps?
Nitrogen Fixation

This is the first step of the nitrogen cycle. This step is characterized by
the conversion of atmospheric N2 into ammonia (NH3). Bacteria like
Azotobacter and Rhizobium have a major role in this process. They
are harbored in the roots of the leguminous plants and help convert
inert nitrogen to ammonia. Nitrogen fixation can occur in any of the
following ways: atmospheric fixation (involves lightening), industrial
fixation (manufacturing ammonia under high temperature and pressure
condition)

Assimilation
Once the nitrogen has been fixed in the soil, plants can absorb
nitrogen through their roots. This process of absorption is known as
assimilation.

Ammonification
This is another process by which ammonia can be generated. Organic
remains of plants and animals are broken down in the soil by some
bacteria to release ammonia into the soil. These dead and waste matter
is used by these microorganisms as food and they release ammonia
into the soil.

Nitrification
This occurs in two-steps. The first step is in which NH3/NH$+ is
converted to NO3- (nitrates). The bacteria Nitrosomonas and
Nitrococcus present in the soil convert NH3 to NO2-, and another
bacterium, Nitrobacter converts NO2- to NO3-. These bacteria gain
energy through these conversions.

Denitrification
Is the reverse of nitrification that occurs in the deep layers of soil
where the bacteria convert NO3- is converted into N2 and other
gaseous compounds like NO2. This occurs because in deep layers of
soil, oxygen is not available and the soil bacteria use these nitrogen
compounds instead of oxygen.
What are some Essential Mineral Elements?
What is the importance of the nitrogen cycle?
● As we all know by now, the nitrogen cycle helps bring in the
inert nitrogen from the air into the biochemical process in
plants and then to animals.
● Plants need nitrogen to synthesize chlorophyll and so the
nitrogen cycle is absolutely essential for them.
● During the process of ammonification, the bacteria help
degrade decomposing animal and plant matter. This helps in
naturally cleaning up the environment.
● Due to the nitrogen cycle, nitrates and nitrites are released into
the soil which helps in enriching the soil with nutrients needed
for cultivation.
● As plants use nitrogen for their biochemical processes, animals
obtain the nitrogen and nitrogen compounds from plants.
Nitrogen is needed as it is an integral part of the cell composition

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