2. Nitro
• an essential part of the amino acids. It is a
basic element of life.
Cyclegen
n + es‘‘nitre forming’’
• composes about four-fifths (78.03 percent)
by volume of the atmosphere.
•in the form of protein is an important
constituent of animal tissue.
• is an important element in plant nutrition.•is inert and serves as a diluent for oxygen in
burning and respiration processes.
3. Nitrogen Cycle
• natural cyclic
process in the
course of which
atmospheric
nitrogen enters the
soil and becomes
part of living
organisms
4. Importance of Nitrogen Cycle
• essential to living organisms and its
availability plays a crucial role in the
organization and functioning of the world's
ecosystems
• key factor controlling the nature and
diversity of plant life
• vital ecological processes such as plant
productivity and the cycling of carbon and
soil minerals
6. Nitrogen Fixation
• nitrogen gas is converted into
inorganic nitrogen compounds. It is mostly
(90 percent) accomplished by free-living,
nitrogen-fixing bacteria.
7. Nitrogen-Fixing Bacteria
• symbiotic bacteria living on the roots of
plants (mostly legumes and alders)
• cyanobacteria (formerly known as blue-
green algae)
• archaebacteria (also known as archaea)
in deep-sea hydrothermal vents
8. Nitrogen Fixation by Haber-Bosch
Process
• method of directly synthesizing ammonia
from hydrogen and nitrogen, developed
by the German physical chemist Fritz
Haber.
9. Nitrogen Fixation by Lightning
• The high energies provided by lightning
and cosmic radiation serve to combine
atmospheric nitrogen and oxygen into
nitrates, which are carried to the Earth’s
surface in precipitation.
11. 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.
15. Nitrification
• a process carried out by nitrifying
bacteria, transforms soil ammonia into
nitrates, which plants can incorporate into
their own tissues.
17. Denitrification
• The process where nitrates are
metabolized by denitrifying bacteria to
free nitrogen and returned to the
atmosphere
18. Human Intrusion and Its Effects
Declination of nitrogen in the soil
• cultivation of croplands
• harvesting of crops
• cutting of forests
19. Human Intrusion and Its Effects
Over supply of Nitrogen
• the production and use of nitrogen
fertilizers
• burning of fossil fuels in
automobiles, power generation plants,
and industries
20. Human Intrusion and Its Effects
Over supply of Nitrogen
• the leaching of nitrogen from over
fertilized croplands,
• animal wastes and sewage
21. Effects of Over Supply of Nitrogen
• substantial acidification of soils and of the
waters of streams and lakes
• acid rain
• Increased global concentrations of nitrous
oxide (N2O), a potent greenhouse gas,
22. Effects of Over Supply of Nitrogen
• stratospheric ozone depletion
• greatly increased transport of nitrogen by
rivers into estuaries and coastal waters
where it is a major pollutant.
