The cycling of phosphorus between the biotic and abiotic components of the environment (see biogeochemical cycle). Inorganic phosphates (PO₄³⁻, HPO₄²⁻, or H₂PO₄⁻) are absorbed by plants from the soil and bodies of water and eventually pass into animals through food chains. Within living organisms phosphates are built up into nucleic acids and other organic molecules. When plants and animals die, phosphates are released and returned to the abiotic environment through the action of bacteria. Small amounts move into the atmosphere as dust or sea spray. On a geological time scale, phosphates in aquatic environments eventually become incorporated into and form part of rocks; through a gradual process of erosion, these phosphates are returned to the soil, seas, rivers, and lakes. Phosphorus-containing rocks are mined for the manufacture of fertilizers, which provide an additional supply of inorganic phosphate to the abiotic environment.

The phosphorus cycle