The Nitrogen Cycle
Nitrogen is the most abundant element in the atmosphere. It is a vital element for all the living systems. It is the primary nutrient for all green plants, but it must be modified before it can be utilized by most living systems.
Four processes participate in the cycling of nitrogen through biosphere
- § Nitrogen Fixation
- § Ammonification
- § Nitrification
- § Denitrification
Nitrogen Fixation
First step in the N Cycle —is the conversion of nitrogen gas (N2) into NH3 or organic nitrogen. Three processes are responsible for the most of the nitrogen fixation in the biosphere:
- § Atmospheric fixation by lighting
- § Industrial fixation by humans
- § Biological fixation by certain microbes, alone or in a symbiotic relationship with plants.
AMMONIFICATION
This is the biochemical process whereby nitrogen is released from nitrogen containing organic compounds. Soil bacteria decompose organic nitrogen forms in soil to the ammonium form. This process is referred to as ammonification.
NITRIFICATION
Nitrification is the conversion of NH4 to NO3. This aerobic reaction is carried out by Autotrophic bacteria.
DENITRIFICATION
This involves conversion ofNO3 to N2 gas in the presence of low oxygen levels.
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