biogeochemical cycles - phosphorous cycle

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phosporous cycle

phosporous in the enviro: 

  • weathering - phosphorous is found in the rocks in abundance 
  • absorption by plants - phosphate salts dissovled in water are absorbed by plants 
  • absorption by animals - animals absorb phosphorous from the plants/by consuming plant eating animals 

 

phosphorus cycle - key steps: 

  • rain + weathering cause rock to release phosphate ions, this inorganic phosphate is then distributed in soils + water 
  • plants take up inorganic phosphate from the soil through symbiotic relationship with Mycorrihizae
  • phosphorous important for biological functions - DNA, cell metabolisms
  • the plants then be consumed by animals, once in plant/animal the phosphate is incorporated into organic molecules e.g. dna 
  • when the plant/animal dies, it decays + the inorganic phosphate is returned to the soil 
  • within the soil organic forms of phosphate be made available to plants by bacteria that break down organic matter to inorganic forms of phosphorous - process is mineralisation 
  • phosphorous in soil end up in waterways + ocean, once their it be incorporated into sediments over time 

where is it found? 

  • phosphate is found in rocks +dissolved in oceans into phosphate ions 
  • found in water (hydropshere), soil + sediments (lithosphere)
  • moves in cyce through rocks, water, soil, sediments + organisms
  • phosphrous much lower availability than other minerals/nutrients as it has low solubility + it not available in the atmosphere - mobalisation of phosphorous is slow 
  • gernally small quantities which limits plant growth 
  • increase this in agriculture by adding fertiliser 
  • phosphate enters food chain - herbivores absorb phosphates 

most phosphorous is unavailable to plants: 

  • as phosphorous is locked up in sediments + plants 
  • availablilty depends on reversible pathways: 
  • bacteria - convert plant…

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