Nitrogen is essential for living organisms but is inert in its atmospheric form. The nitrogen cycle transforms nitrogen between its gas, organic, and inorganic forms through biological and environmental processes. These include nitrogen fixation by bacteria, ammonification by decomposers, nitrification by bacteria, and denitrification by other bacteria. The cycle is crucial for providing nitrogen to plants and recycling waste nitrogen back into usable forms and the atmosphere.

1. Presented by :
Parmar suraj
Paper-303
Botany

2. Nitrogen
Cycle

3. INTRODUCTION
• Nitrogen Cycle is a biogeochemical process which
transforms the inert nitrogen present in the
atmosphere to a more usable form for living
organisms.
• Nitrogen is a key element for plants.
• All organisms required nitrogen to live and grow.
• But atmospheric nitrogen cannot be used directly by
plants or animals.

4. • The main aviability of nitrogen in atmosphere
is about to 78%.
•In 1897 m.w bejerink discover symbiosis
nitrogen Fixer.
•Nitrogen are in two forms:
* Organic
* Inorganic

6. Contents
 Nitrogen fixation
 Ammonification
 Nitrification
 De-nitrification
 Importance
Nitrogen cycle(N2)

7. Nitrogen fixation
NitrogenFixation
• The process of converting inert nitrogen into biologically
available nitrogen is called nitrogen fixation.
• In this process of N2 fixation the Inert
Form of nitrogen Deposited into soil from the atmosphere and
surface water.
•This intire process is completed by symbiotic bacteria
called Diazotrophs.
•Azatobactor and Rhizobium have a major role in this
process.

8. • Three process responsible for most of the nitrogen
fixation.
1) Atmospheric Fixation (Lightning⚡)
2) Industrial Fixation
3) Biological fixation
1) Atmospheric Fixation by lightning
•The lightning breaks Nitrogen molecule, their
broken molecules combines with oxygen and form
nitrogen oxide.
• Then it comes Through rain water Into the soil.

9. 2) Industrial Fixation
• It is a man-mad alternative.
• Under the great pressure about 600°c
Nitrogen and hydrogen combines and forms
ammonia.
• Later, it is converted into various fertilsers
such as urea.
3) Biological Fixation
•Maximum nitrogen fixation process done
by biological fixation.

10. •Nitrogen Is not used directly from the air
by the plants and animals.
•Bacteria like rhizobium and blue green
algae transforms the unusable form of
nitrogen into other compounds that are
more usable.
•These nitrogen compound get fixed in the
soil by these microbes.
N2 No2 and No3

11. •Ammonification is the process in which
ammonia releases through the
decomposition of dead bodies and waste of
living Organisms.
•Various fungi and prokaryotes Decompose
the tissue containing organic nitrogen and
release inorganic nitrogen back into the
ecosystem as ammonia(NH3) or
Ammonium ion.
Ammonification

12. Nitrification
• The process in which the ammonia is converted into
Nitrite(No2) and then Nitrate (No3) is refered as
nitrification.
• By the oxidation of ammonia nitrite are formed with
the help of Nitrosomonas bacteria species.
• NH3
• Then nitrite (no2) converted into Nitrates (no3) by
Nitrobacterium species.
•
Nitrosomonas No2
No2 Nitrobactor No3

13. De-Nitrification
• De-nitrification is the process in which the nitrogen
compond makes it's way back into the atmospheres by
converting Nitrates into gaseous form of nitrogen.
• This process is carried out by the de-nitrifying
bacterium species.
• Ex: Clostridium and Pseudomonas
• This is the Final stage occurs in the absence of oxyge.

14. Importance of Nitrogen Cycle
1) It helps plants to synthesise chlorophyll from the
nitrogen compounds.
2) Helps in converting nitrogen gas into a usable form
for the plants through biochemical process.
3) The cycle indirectly helps to clean-up the
environment.
4) N2 cycle helps in enriching the soil with nessesary
nutrients required for cultivation.