1. Biogeochemical cycles
Nitrogen Cycle
Biogeochemical cycles

2. The Nitrogen Cycle
All organisms require nitrogen to make amino acids, which in turn are used to build proteins.
78% of the Earth’s atmosphere
There are certain bacteria that can convert nitrogen gas into ammonia. – This is called Nitrogen Fixation
Other soil bacteria convert nitrates into nitrogen gas – This is called Denitrification.

4. Phosphorus Cycle
Phosphorus doesn’t enter into the atmosphere like water, carbon, and nitrogen.
Most of the phosphorus comes from rock and soil minerals.