NUTRIENT
CYCLE- power point
presentation

The Nutrient Cycle
 Nearly 30-40 elements are required for proper growth
and development of living organism.
 Most important of these are C, h, O, P, K, N, S, Ca, Fe,
Mg, B, Zn, Cl, Mo, Co, I, and F.
 These elements flow from abiotic to biotic components
and back to the non living component again in a more
or less cyclic manner. This is known as Nutrient
Cycles.

Types
 There are 3types of nutrient or biogeochemical cycles:
-hydrologic cycle or water cycle
-gaseous cycle
-sedimentary cycle
 The nutrient cycle focuses primarily on two nutrients,
carbon and nitrogen (of the gaseous cycle).

Gaseous cycle
 Biogeochemical cycles in which reservoir is the air or
oceans(via evaporation).
 Include those of nitrogen, oxygen, carbon, and water.
 Tend to move more rapidly than do sedimentary ones
and to adjust more readily to changes in the biosphere
because of the large atmospheric reservoir.

Nitrogen cycle
 Biogeochemical cycle by which nitrogen is converted
into various chemical forms as it circulates among the
atmosphere, terrestrial and marine ecosystems.
 Conversion of nitrogen can be carried out through both
biological and physical processes.
 Majority of earth’s atmosphere is nitrogen(78%).
However, atmospheric N2 has limited availibility for
biological use, and this form is relatively non-reactive
and unusable by plants.

Steps of nitrogen cycle

Elaboration
 Nitrogen fixation- atmospheric nitogen must be fixed in a
usable form to be taken up by plants, mostly fixation is
done by free living (eg. Azotobacter & Closteridium) or
symbiotic (Rhizobium).
 Nitrification- conversion of ammonia to nitrate is
performed primarily by soil living bacteria and other
nitrifying bacteria. (eg. Nitrosomonas sp.- ammonia to
nitrites & Nitrobacter sp.- nitrite to nitrate.)
 Assimilation – plants take nitrogen from soil by
absorption through their roots as amino acids, nitrate
ions, nitrite ions or ammonium ions.

 Ammonification- when a plant or animal dies or an
animal expel waste , the initial forms of nitrogen is
organic. Bacteria or fungi convert the organic nitrogen
within the remains back into ammonium , a process
called ammonification or mineralization.
 Denitrification- reduction of nitrates back into the largely
inert nitrogen gas, completing the nitrogen cycle.(
bacterial species involved are Pseudomonas &
Clostridium)

Carbon cycle
 Combined process, including photosynthesis,
decomposition, and respiration, by which carbon is a
component of various compound cycles between its
major reservoirs- the atmosphere, oceans and living
organisms.
 Carbon cycle is the biogeochemical cycle by which
carbon is exchanged among the biosphere, pedosphere,
geosphere, hydrosphere, and the atmosphere of the
Earth.

Elaboration
 Carbon moves from the atmosphere to plants. In the
atmosphere, carbon is attached to oxygen forming
carbondioxide through the process of photosynthesis
carbon dioxide is pulled from the air to make plant food
from carbon.
 Carbon moves from plants to animals. Through food
chains, the carbon that is in plants moves to the animals
that eat them. Animals that eat other animals get the
carbon from their food too.
 Carbon moves from plants and animals to the ground.
When plants and animals die, their bodies, wood and
leaves decay bringing the carbon into the ground. Some
becomes buried and become fossil fuels.

 Carbon moves from living things to the atmosphere. Each
time you exhale, you are releasing carbon dioxide gas
into the atmosphere.
 Carbon moves from fossil fuels to the atmosphere when
fuels are burned.
 Carbon moves from the atmosphere to the oceans. The
oceans and other bodies of water, soak up some carbon
from the atmosphere.

Significance
 The nitrogen cycle is important due to its role as a basis for the
production of nitrogen that is essential to all forms of life.
 Nitrogen is required for the synthesis of amino acids, nucleic acids
(DNA & RNA) in chlorophyll molecules. It is an essential component
of the proteins that build cell materials, and plant tissue.
 Carbon is the fundamental building block of life and an important
component of many chemical processes.
 Increased levels of carbon dioxide insulate the earth, causing
temperatures to rise. Understanding how carbon dioxide is
absorbed and released helps us to understand the climate and
predict global warming.
 Carbon is not in balance, so it’s important to learn where it is being
stored and released. The rate at which carbon is deposited is not
the same as the rate it is returned to the Earth.

Reference
 Steven B. Carroll ; Steven D. Salt (2004). ECOLOGY FOR
GARDENERS. Timber press. P. 93. ISBN 978-0-88192-611-8.
 Galloway, J.N.; et al.. (2004). “Nitrogen cycles: past, present, and
future generations”.
 Steffen, w. (2000) ; Linder, ‘’THE GLOBAL CARBON CYCLE: A
TEST OF OUR KNOWLEDGE OF EARTH AS A SYSTEM”
 Prentice, I.C. (2001).” THE CARBON CYCLE AND ATMOSPHERIC
CARBON DIOXIDE ” climate change 2001.
 “AN INTRODUCTION TO THE GLOBAL CARBON CYCLE”
University of New Hampshire. 2009. Retrieved 6 February 2016.

Thank you…