The Phosphorus Cycle

Interesting Facts

• Phosphorous is a non-metal

• It is essential for the body's energy transport molecules and for holding DNA and RNA molecules together

• Many non-metals are absolutely essential for body functioning like nitrogen, oxygen, sulfur, etc.

More Facts…..

• Oxygen, carbon and nitrogen cycles include gases in the atmosphere. The phosphorous cycle is an example a non-metal cycle that does not have a gas as part of its cycle.

Importance of Phosphorus

Phosphorus, mainly in the form of the ions, is an essential and important nutrient of both animals and plants.

What is the Phosphorus Cycle?

The phosphorus cycle occurs in many different ways. It can be seen from a soil-based view, an ecosystem like view and in a global view.

The Phosphorus Cycle

Animalmanures

and biosolids Mineralfertilizers

Crop harvest

Runoff anderosion

Leaching(usually minor)

Organic phosphorus•Microbial•Plant residue•Humus

Primaryminerals(apatite)

Plant residues

Plantuptake

Soil solutionphosphorus•HPO4

-2

•H2PO4-1

Secondarycompounds

(CaP, FeP, MnP, AlP)

DissolutionDissolution

PrecipitationPrecipitation

Mineralsurfaces

(clays, Fe and Al oxides,

carbonates)W

eath

erin

g

Wea

ther

ing

AdsorptionAdsorption

Mineralization

Mineralization

Immobilization

ImmobilizationDesorptionDesorption

Input to soilComponent Loss from soil

Atmosphericdeposition

One Example of the cycle

Phase One

1) Phosphate Rocks

Phase Two

2) Mining of rocks rich in phosphorous:

Mining rocks rich in phosphate are mainly used for agricultural. They are essential ingredient in fertilizers. Without it, our plants would not grow

Phase Three

3) Fertilizers contain both nitrogen and phosphates. Both of which are essential for living cells. The phosphate is essential for DNA, RNA.

Phase Three (cont.)

If farmers place too much fertilizer on their fields, this may alter the phosphorus cycle. An excess of phosphates entering from farmland runoff or erosion may cause rapid growth of algae and other kinds of plants that live in water.

Phase Four

4) The growth of crops and plants removes phosphates and nitrogen from the soil.

Phase Five

5) Soil Phosphates are added to the soil by fertilizers or by the excreted products of living things.

Phase Six

6) Plants or producers are the key in passing on phosphates to other living things. Phosphate enters the plants through the root system. Once inside they become part of the plant's DNA and RNA.

Phase Seven

7) Animals receive their phosphates from producers either directly or indirectly. Example: A) A mouse eats a plant

*considered directly

B) Wolf eats the mouse

*considered indirectly

Phase Eight

8) Through feces, urine, and decay of dead plants and animals, phosphates return to the soil either to be….

to be……….

Option A

carried to other areas by erosion

Option B

returned to producersor

Phase Nine

9) Over time , phosphates are slowly dissolved from rocks by chemical weathering mainly through rain and melting snow. It is then carried into waterways where it enters the water or aquatic phase of the phosphorus cycle.

Phase Ten

10) After reaching the ocean, the phosphate is then integrated with the plants or producers. As on land, the plants are necessary for the animals to get there phosphate.

Phase Eleven

11) Next, animals ingest the plants and by doing so receive the needed phosphate. Once again the idea of direct and indirect comes into play Example: Little fish eats a plant

*Direct Big fish eat little fish

*Indirect

Phase Twelve

12) In the next step there are two possible outcome. Sea life returns phosphates as dissolved phosphates through death or through excretion of waste materials from their cells or bodies. From here they can either…..

Phase twelve continued

Return to the plants

and producers

Settle at the bottom and form marine

sediments

or

Phase Thirteen

13) If the dissolved phosphate becomes marine sediments it can remain at the bottom of a body of water indefinitely. The process by which it is brought back to the surface is known as crustal uplift

Phase Fourteen

14) Erosion is also part of the phosphorus cycle. In the cycle it occurs in the surface runoff carrying phosphates in a dissolved form to a water environment.

End of Sample Cycle

Phosphorus Cycle in Lakes

Another prime example of the cycle occurs in lakes. 

• Aquatic plants take in dissolved inorganic phosphorus. 

•Once again the idea of indirect and direct comes into play as the animals eat the plants and one another to get it.

•Dead animals phosphorus either goes to the plants again or go to the bottom and the cycle repeats

Other ways the cycle can occur

In Soil

In soil, phosphate is absorbed on clay surfaces and organic matter particles and becomes incorporated . Animals then eat the plants to get the phosphorus and others eat them and continue the cycle.

Soil continued

As the animals die they release phosphorus as a waste product in urine and feces. Phosphorus is then released back to the soil when plants or animal matter decomposes and the cycle repeats.

Example

Globally

• The earths crust is a main holding place for phosphorus.

• On land it is found as phosphates. • Through erosion phosphates enter rivers

and streams which lead them to the ocean.• Once in the ocean the phosphorus

accumulates on continental shelves in the form of insoluble deposits.

Global continued

• Over time the crustal plates rise from the sea floor and expose the phosphates on land.

• After more time, weathering will release them from the rock and the cycle's geo-chemical phase begins again.

Inorganic Available Phosphate

Uptake of Phosphate

Crop residue and manure return

phosphate to soil

Phosphate Added in Fertilizer

Removal by crops

Runoff to Water Body

Fixed Phosphate

Mineralization of Organic

Phosphate

Fin

Bibliography

1.http://soils1.cses.vt.edu/ch/biol_4684/Cycles/Pcycle.html2. http://www.lenntech.com/phosphorus-cycle.htm3. http://www.cst.cmich.edu/centers/mwrc/phosphorus%20c

ycle.htm4. http://www.specialedprep.net/MSAT%20SCIENCE/Cycl

eP.htm5. http://gsa.confex.com/gsa/2002AM/finalprogram/abstract

_40198.htm6. http://www.elmhurst.edu/~chm/vchembook/308phosphor

us.html 

7. http://www.cnr.berkeley.edu/benninglab/Students/David/casa/P.html