The Nitrogen Cycle
Atmospheric Nitrogen
Volcanic Action
Blue-green algae
Nitrogen-fixing
In the world’s seas
bacteria in soil and
and oceans
root nodules of
Lightning Fixation
Nitrates taken up
by plant roots
Plant and Animal
Protein
Dead organisms
Denitrification Bacteria
and feces
in swamp or boggy soil
legumes (clover,
Plant and animal
beans, peas)
Ammonia Salts
Proteins
Artificial inorganic fertilizer
Dead organisms
And feces
Lost to marine sediment
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Soil Nitrates
Nitrifying Bacteria