Breakdown of rocks is the primary natural source for Phosphorus and Potassium.
Algae and other aquatic organisms help Nitrogen, Carbon, and Oxygen cycle through bodies of water.
Fertilizer use can cause pollution when too much Phosphorus is transferred into bodies of water.
Volcanic activity releases Nitrogen and Oxygen into the atmosphere.
Fertilizers on crops and lawns add Nitrogen, Potassium, and Phosphorous to the soil.