Phosphorous is another element that is universal to all living things. Phosphorous is used in the production of fertilizers, toothe paste, pesticides, explosives, nerve agents, and friction matches. It exists elementally in two forms, as white phosphorous and red phosphorous.
The phosphorous cycle is a cycle that allows phosphorous to be used in various forms and compunds, then be recycled for use all over again. Phosphorous is used to make fertilizer for plants, so plants absorbing the phosphorous from the ground would be one example.
People and animals eat the plants that have phosphorous as part of their molecular makeup. The phosphorous takes various forms in the people and animals, found in DNA, RNA, ATP, and the phospholipids that comprise the cellular membranes of every living thing. That would be another example.
Phosphorous can also be excreted from the people's and animal's bodies. Elemental phosphorous was first discovered in human urine. Bone ash, the leftover remains of animal bones, has long been used as an escellent source of fertilizer because it contains phosphorous that can replace the phosphorous in the soil the plants consume. There is the third and final example.
this might help: http://filebox.vt.edu/users/chagedor/biol_4684/Cycles/Pcycle.html