Phosphorus Cycle

• phosphorus important biological functions


  -bones

  -ATP

  -DNA

  -RNA

  -cell membrane

  -proteins
• how is phosphorus a limiting factor in biological processes?


  -low solubility

  -no gaseous reservoir
• main processes of the phosphorus cycle


  Absorption by roots, decomposition, sedimentation, mountain building and weathering
• absorption by roots


  plant roots absorb phosphate that they will use in metabolic processes

  -They are not effective at absorbing phosphate so plants have symbiotic relationships with fungi

  -The networks of fungal hyphae in the soil create a large surface area
• Decomposition


  The breakdown of phosphorylated proteins in dead organic matter releases phosphate that are often more soluble by soil microbes so they can be absorbed into the plant
• Sedimentation


  Phosphorus and organisms that die and become rocks are no longer available to other organisms

  (Plankton die + sink to ocean floor)
• weathering and mountain building


  Phosphorus in marine sediment may not be available until continental drift which creates new mountains and then weathering to release phosphate
• Human impacts on the phosphorus cycle


  Mining of phosphate rocks, fertiliser use
• Mining phosphate rocks


  Most phosphorus is mined as calcium phosphate then treated to produce ammonium phosphate which is more soluble
• Fertiliser use


  The use of fertilisers mobilises phosphorus compounds into the environment in more soluble forms. This increases crop production but can also contribute to eutrophication.
• Sustainable management of the phosphorus cycle


  -Biological waste should be used as fertilisers to maintain phosphate nutrient availability

  -Crop breeding programs increasing the efficiency of phosphate absorption by crops