Answer:
The body needs phosphorus to build and repair bones and teeth, help nerves function, and make muscles contract. Most (about 85%) of the phosphoruscontained in phosphate is found in bones. The rest of it is stored in tissues throughout the body. The kidneys help control the amount of phosphate in the blood.
The main difference is that there is not a significant reservoir of phosphorous in the atmosphere, while both nitrogen and carbon are found in large amounts in the atmosphere.