Phosphorus circulates though water,the earth's crust,and living organism in the phosphorus cycle, depicted in figure 3-5. In contrast to the cycles of water,carbon,and nitrogen,the phosphorus cycle does not include the atmosphere.The major reservoir for phosphorous is phosphate salts containing phosphate ions in terrestrial rock formation and ocean bottom sediments.The phosphorus cycle is also slow compared to the water,carbon,and nitrogen cycles.
As water runs over exposed phosphorus-containing rocks,it slowly erodes away inorganic compounds that contain phosphate ions.The dissolved phosphate can be absorbed by the roots of plants and by other producers.Phosphorous is transferred by food webs from producers to consumers,eventually including detritus feedders and decomposers.in both producers and consumers,