Cycling Of Nitrogen
In The Biosphere
University Of Rajshahi
Submitted by
1.Md Yesir Arafat
2.Saon Priya Shova
3. Aminul Islam

78% 21% < 1%
The Study Of Earth's Atmosphere

Nitrogen Cycle
a continuous series of natural
processes by which nitrogen
passes from air to soil to
organisms and back to air or
soil involving nitrogen fixation,
nitrification, amminofication
(decay) , and denitrification.

There are 5 Step’s of nitrogen cycle:
1.Nitrogen Fixation
2.Nitrogen Assimilation
3.Ammonification
4.Nitrification
5.Denitrification

1.Nitrogen Fixation
2.Nitrogen Assimilation
3.Ammonification
4.Nitrification
5.Denitrification
N2 N2 N2
NH3
+/NH4
There are 5 Step’s of nitrogen cycle:

1.Nitrogen Fixation
2.Nitrogen Assimilation
3.Ammonification
4.Nitrification
5.Denitrification
NH3
+/NH4
Organic N
There are 5 Step’s of nitrogen cycle:

1.Nitrogen Fixation
2.Nitrogen Assimilation
3.Ammonification
4.Nitrification
5.Denitrification
NH3
+/NH4
Organic N
There are 5 Step’s of nitrogen cycle:

1.Nitrogen Fixation
2.Nitrogen Assimilation
3.Ammonification
4.Nitrification
5.Denitrification
NH3
+/NH4
NO3
-
There are 5 Step’s of nitrogen cycle:

1.Nitrogen Fixation
2.Nitrogen Assimilation
3.Ammonification
4.Nitrification
5.Denitrification
NO3
-
N2 N2 N2
There are 5 Step’s of nitrogen cycle:

1.Nitrogen Fixation
2.Nitrogen Assimilation
3.Ammonification
4.Nitrification
5.Denitrification
There are 5 Step’s of nitrogen cycle:

Atmosphere
Biosphere
N2 N2 N2
NH3/ NH4
+
Nitrogen Fixation
NO2
-
NO3
-
Nitrofication
PLANT ANIMAL
Assimilation
DICOMPOSER
Amminification
Di Nitrofication
THE NITROGEN CYCLE

1. Nitrogen Fixation
Atmosphereic nitrogen gas is converted into inorganic nitrogen
compounds. Nitrogen gas can be fixed in three ways.
I. Atmospheric fixation.
II. Industrial fixation.
III. Biological fixation.

I. Atmospheric Fixation
This occurs spontaneously by Lightning; only a small amount (5–8%)
is fixed this way. Lightning allows nitrogen and oxygen to combine to
produce various oxides of nitrogen. These are carried by the rain into
the soil where they can be used by plants.

II. Industrial Fixation.
Haber-Bosch Process method of directly synthesizing ammonia from
hydrogen and nitrogen, developed by the German physical chemist
Fritz Haber. This is a very energy-inefficient process.

III. Biological fixation.
Biological nitrogen fixation is an important process in the soil, carried
out by several groups of bacteria and actinomycetes able to absorb
nitrogen from the atmosphere and combine it into compounds that serve
as nutrients from plants.Nitrogen-fixing bacteria are Rhizobium,
Clostridium, Azotobacter etc, fix 60% of nitrogen gas in the
atmosphere.

2. Nitrofication
a process carried out by nitrifying bacteria such as
Nitrosomonus, Nitrobactor , transforms soil ammonia
into nitrates, which plants can incorporate into their own
tissues.

Nitrogen Assimilation are assimilation of nitrates and ammonia
resulting from nitrogen fixation into the specific tissue compounds of
algae and higher plants. Animals then ingest these algae and plants,
converting them into their own body compounds.
3.Nitrogen Assimilation
3

4.Ammonification (decay)
The decomposers, certain soil bacteria and fungi, break down proteins in
dead organisms and animal wastes, releasing ammonium ions which
can be converted to other nitrogen compounds

5.Denitrification
The process where nitrates are metabolized by denitrifying bacteria
Pseudomonas to free nitrogen and returned to the atmosphere.

Importance of Nitrogen Cycle
• Maintain Optimum growth of Plants ,
• majority of nitrogen is obtain from the atmosphere is
used in the production of NH3 (Haber process) which is a
raw source for the manufacture of Nitric acid (Ostwald
process).
• Synthesis natural and artificial Fertilizer e.g, Ammonium
Sulphate.

Thank you
MD YESIR ARAFAT
BMB-36
CREATOR