nutrient cycles and fertilisers

• detritovores are organisms that break down dead tissue such as worms and woodlice
• decomposers are organisms that break down dead organic matter
• saprobionts secrete enzymes for extracellular digestion to create small soluble molecules
• mychorrhizae are associations between fungi and roots of plant. they extend the plant roots to increase the surface area for absorption of water and minerals. this is a mutualistic relationship between plant and mychorrhizae. mychorrizae gain amino acids and sugars while plant gets improved water adsorption.
• phosphates enter crops by fertilliser. animals eats crops and phosphate from animals waste runs off into rivers. algae absorbs the phosphate which aquatic animals eat. phosphate is then released during decomposition. phosphates build back up into rocks during sedimentation.
• nitrogen fixing bacteria converts Nitrogen gas to ammonia which is taken up by legumes.
• nitrogen fixing bacteria converts nitrogen gas to ammonium in soil
• nitrifying bacteria convert ammonium to nitrite ions
• nitrifying bacteria converts nitrite ions to nitrate ions
• plants absorb nitrate ions by assimilation
• denitrifying bacteria convert nitrate ions back into nitrogen gas from soil to the atmopshere
• dead mater converts to ammonium ions by ammonification
• organic fertiliser is farmyard manure (faeces and waste straw)
• inorganic fertiliser is manufactured that contains nitrates and phosphates
• disadvantages of inorganic fertilisers

  • easily leached from soil
  • can damage ponds and lakes
  • expensive and can spread to other areas
• advantages of inorganic fertiliser

  • concentrated so only a small amount is needed
  • lack odour compared to manure
  • releases easily in the soil
• effects of using fertiliser

  • reduces species diversity
  • leaches easily from soil
  • can cause eutrophication
• eutrophication is the effect of increased nutrients in aquatic ecosystems. they can cause huge algae blooms