Without an adequate supply of P, plant growth is diminished, maturity delayed, and yield reduced. When plants die, P is returned to the soil, where it can be used by soil microorganisms and other plants. The P cycle repeats until P is lost at the bottom of the seas and becomes fixed in sedimentary rock, to be released if the rock surfaces and is weathered. Role of P in human and animal nutrition Humans and other animals obtain P from eating plants, and use it to make bones, teeth, and shells. Phosphorus is excreted as phosphate and organic-P compounds.
Soil microbes recycle P for plant uptake, thereby making it available to all animals.
The remainder is used for other body processes including the metabolism of red blood cells and ATP production. ATP is an energy-rich compound that fuels activity in the body's cells. Because ATP in muscle cells is used rapidly during contraction, ATP has to be continually resynthesized to supply energy to the cells. Phosphorus is important in the diets of livestock as well. Phosphorus and other nutrients are required for bone strength and the production of muscle.