Bio-geo-chemical cycles	Biotic processes	Abiotic processes
1. Carbon cycle
2. Oxygen cycle
3. Nitrogen cycle

Bio-geo-chemical cycles	Biotic processes	Abiotic processes
1. Carbon cycle	Photosynthesis, Respiration, Decomposition	Burning of fossil fuels, forest fires, volcanic activity.
2. Oxygen cycle	Photosynthesis, Respiration, Decomposition.	Combustion, Corrosion, rusting, formation of ozone (O3 )
3. Nitrogen cycle	Biological nitrogen fixation, ammonification, nitrification, denitrification	Atmospheric nitrogen fixation, industrial nitrogen fixation.