SCIE- Earth Cycles: Nitrogen Cycle

Nitrogen Cycle

• Continual movement of nitrogen, and bacteria perform a lot of this movement. Also, nitrogen must be fixed before it can be used by plants.

Nitrogen Fixation

• The change of nitrogen gas (78% earth’s atmosphere) to either ammonium NH4 or nitrates NO3 from the soil.

Ways Nitrogen Fixation Happens:

• fixation by lighting when it separates nitrogen gas into nitrogen atoms which bond with oxygen to form nitrates

• biological fixation where bacteria in legumes work to provide host plan ammonium

• ammonification and nitrification

Assimilation

• Once nitrogen items can be used, plants absorb it and use it to make proteins, nucleic acids, and other biomolecules

• moves along food chain

Animal Urine

• Animal urine contains nitrogen and returns it back into the soil

Decomposers

• When an organism dies, decomposers will break down biomolecules and release nitrogen atoms back into the soil

Denitrification

• Some bacteria that use nitrate to return nitrogen to the atmosphere where the cycle starts again