Nitrogen Cycle

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Nitrogen Cycle

• Topic 1016 D
• Matt Jakubik

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Facts

• Earths Atmosphere is almost 80 nitrogen (N2)
• Most nitrogen is added to soil by rain or dust
  particles
• Some plants have bacteria help with nitrogen
  uptake
• Others have aerial roots that can absorb from the
  air

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Processes

1. Nitrogen Fixation
2. Mineralization
3. Nitrification
4. Immobilization
5. Denitrification

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Nitrogen Fixation

• N2 taken from the atmosphere to the plant
• Nodules on legumes
• Bacteria-Rhizobium
• Ammonia applied to soil
• Soil picks up H

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http//biology.kenyon.edu/courses/biol272/agricult
ure/nodulation2.jpg
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Mineralization

• Also called ammonification
• 99 of soil nitrogen is organic nitrogen in
  organic matter
• 1-2 is mineralized each year
• Nitrogen from manure

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Nitrification

• Oxidation of ammonium (NH4) to nitrite (NO2-) to
  nitrate (NO3-)
• Two step process
• Process will not take place in saturated soils

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Immobilization

• Conversion of Inorganic (minerals) Nitrogen to
  organic nitrogen
• Stable in the soil

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Denitrification

• Reduction of nitrate or nitrite by microbial
  activity
• Gaseous process
• Escapes the soil
• Prevents nitrogen in groundwater as overabundance
  occurs

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Online Activity