The Phosphorus Cycle

"Phosphorus is a key element in cell membranes, in molecules that help release chemical energy, in the making of the long molecules of DNA, and in the calcium phosphate of bones" (Ritter, 2001, pg.68). The phosphorus cycle is different from the carbon and nitrogen cycles as phosphorus cannot be in the gaseous state in the atmosphere (Environmental Impacts of Agriculture, Phosphorus Cycle).  

Phosphorus cycles in two ways: a long-term cycle involving the rocks of the Earth's crust, and a short-term cycle involving living organisms.

Living things take in phosphorus from the normal/long rock cycle as phosphorus is found in bedrock in the form of phosphate ions (Ritter, 2001, pg.68). Since phosphates are soluble in water, they can be dissolved out of rock, which then can be absorbed by photosynthetic organisms and be passed into food chains. "Phosphates eroded from rock are also carried by water from the land to rivers, and then to the oceans" (Ritter, 2001, pg.68). Phosphates are absorbed by aquatic plants in the ocean as animals use phosphates to make bones and shells, and they enter food chains. When the organisms die, their remains form deposits on the ocean floor, which become covered with sediment. The deposits gradually become rock, and they get brought up to the surface to continue the cycle which may take millions of years to complete.

The short cycle consists of wastes from living things being recycled by decomposers, which break down wastes and dead tissues and release the phosphates (Ritter, 2001, pg.68).