Phosphorus Cycle

• Phosphorus in nature is never found in free state because it is oxidized with oxygen.
• It is present in huge amounts as Ca (PO₄)₂& other salts in the soil. In the living organisms, phosphorus occurs in the form of nucleic acids, nucleoproteins, phospholipids, phytin, phosphorylated sugars, co-enzymes etc.
• In soil, phosphorus is also added in the form of chemical fertilizers (DAP, calcium dihydrogen phosphate, ammonium phosphate) or in the form of dead plants & animals residue.
• In the soil, 25-85% of total phosphorus is present in the form of organic compounds but it is not utilized directly by plants.
• Living plants can utilize soluble inorganic phosphorus (calcium hydrogen phosphate). The transformation of mineral or organic phosphorus into soluble inorganic phosphorus is brought about by microbial action.
• Plants utilize this available phosphorus; transform it into organic & inorganic phosphorus.
• Phosphorus comes in the body of animals excreta, contains also organic phosphorus which is changed into available forms by microbes.