phosphorus cycle

what form is phosphorus found in?

mineral form (rocks)

phosphorus cycle - land

- phosphate ions (PO43-) in rocks are released into the soil by weathering
- PO43- taken into plants through roots (mycorrhizae increase the rate of assimilation)
- PO43- transferred through the food chain
- excess PO43- excreted
- dead/decaying organisms are decomposed by saprobionts, releasing PO43- into soil or water
- can remain in bones/shells which erode slowly and are deposited to reform sediment

phosphate cycle - aquatic

• weathering of rocks also releases PO43- into seas, lakes and rivers

• this is taken up by aquatic producers (e.g. algae) and passed along aquatic food chains, to birds

• “guano” contains high proportion of PO43-

• guano returns PO43- to soil - a natural fertiliser

guano

waste produced by birds

suggest one way in which an increase in the uptake of phosphate could increase plant growth

used to produce ATP in cells