Nitrogen Cycle
1. Equations in Nitrogen Cycle
1. Nitrogen fixing bacteria break stable
nitrogen bond. (Called nitrogen fixers)

N2 →NH3 or NH4. 2. Other bacteria
convert into NO2 and NO3
2. Plants use NH4 or NO3 to produce
nitrogen containing organic molecules

Passed on to animals when plants consumed
3. Humans capture N2 + 3H2→ 2NH3 or NO3 in commercial fertilizers.
4. When organisms die they release their stored nitrogen, some of the
nitrogen is converted to inorganic compounds like NH4 NO2 NO3
2. Organic reservoirs: Plants, and they then give nitrogen to heterotrophs and
decomposers
3. Inorganic reservoirs: the air which contains 78% nitrogen gas
4. Nitrogen Cycle
1. Nitrogen Fixation N2
NH4+ with bacteria on legumes

Can also break N2 bond through lightning, forest fires, and hot lava flows
2. Nitrogen Uptake NH4+
Organic N turned into organic proteins and
compounds and transferred up the food chain
3. Nitrogen Mineralization Organic N
NH4+ Decay
+
4. Nitrification NH4
NO3 bacteria gain energy when convert ammonia to nitrate
 Ammonium can’t be washed out while nitrate can-leads to bad soil in one area
and good in another
5. Dentrification NO3N2+ N2O
 Bacteria follow this NO3NO2NO
N2O
N2.
 Takes out of biome...the only way!!
5. Impact of human intervention on cycle
1. Non-leguminous crops are fertilized with industrial fixated nitrogen
2. byproducts of fossil fuels create fixation in atmosphere
3. these double the rate that nitrogen is moved from our atmosphere to the
lithosphere
 causes
acid deposition in lakes and ponds, damage to forests, ozone pollution,
climate change, and stratospheric ozone depletion