nutrient cycle

• nitrogen cycle: nitrogen fixation

  nitrogen gas ---> nitrogen containing compounds

  nitrogen fixing bacteria from plants turn nitrogen to ammonium ions
• nitrogen cycle: nitrification

  nitrifying bacteria turns ammonium ions to nitrites

  nitrifying bacteria turns nitrites to nitrates

  • requires oxygen (aerobic respiration)
• nitrogen cycle: ammonification

  saprobionts break down nitrogen containing compounds into ammonia

  • released into soil to form ammonium ions
• nitrogen cycle: denitrification

  nitrates convert into nitrogen gas using denitrifying bacteria

  (anaerobic respiration)
• phosphorus cycle:

  phosphorus in water + soil

  • released via weathering - sedimentation (creates rocks)
  • plants absorb these ions - eaten by animals
  • animals excrete phosphate ions
  • decomposition - saprobionts breaks down the compounds releasing phosphate ions
• use of fertiliser

  replace mineral ions (nitrate + phosphate) lost 
• pros and cons to natural fertilisers

  pros: cheaper

  cons: no exact proportions to amount of ions
• pros and cons to artificial fertiliser

  pros: can controls the proportions of ions

  • water soluble - highly soluble

  cons: water soluble - can be leeched 
• process of eutrophication 

  • mineral ions leeches-  causes rapid growth of algae on surfaces of water
  • blocks sunlight so plants cannot photosynthesise
  • bacteria feed on dead plant matter - reduces oxygen conc due to aerobic respiration
  • aquatic organisms die due to lack of oxygen conc