Definition: Cycling of
phosphorus between the biotic
and abiotic component of the
1. Phosphorus is an essential compound of
nucleic acid (DNA, RNA)
other important organic compounds
2. It is an uncommon element, forms no gaseous
compounds and is often a limiting factor in the
biotic productivity of ecosystems.
3. Inorganic phosphate ions are absorbed
(active ion uptake) by plants, then assimilated
to synthesis important compounds.
4.The organic phosphates from plants are
transferred to herbivores when eaten by
animals and then transfer to other trophic
levels in the food chains.
5. Marine birds feeding on fish can cycle back
some phosphates (through decomposition of
dead bodies, excreta) to the soil.
6. Phosphorus is returned to the soil when
organisms die.The remains of bones, teeth,
shells and excretory wastes are acted on by
phosphotising bacteria to release inorganic
7.Through the process of erosion, inorganic
phosphates are returns to the soil, rivers,
lakes, seas and oceans.There is
sedimentation of phosphates on the ocean
8. After millions of years, geological land uplift
raised the rocks containing phosphorus above
9. Erosion and mining of the rocks for
manufacture of fertilisers supply inorganic
phosphates to the soil.