Decay

• Decomposition - the breakdown of dead materials into simple organic matter
• What is decomposition done by?

  Decomposers (fungi and bacteria) and detritivores (worms etc).
• Detritivores are animals which feed on dead organic matter.
• Factors which affect the rate of decomposition;

  • Oxygen
  • Moisture
  • Temperature
• How oxygen affects rate of decomposition;

  More oxygen = more aerobic respiration = more energy released = faster rate of decomposition
• How temperature affects the rate of decomposition;

  Higher temperature = particles have more kinetic energy and enzymes are closer to optimum temperature = higher rate of reactions = more decomposition

  However, if temperatures rise too high, it will cause the enzymes to denature = decreasing rate of reaction = decreasing rate of reaction.
• How water/moisture affects rate of decomposition;

  • As decomposers need water to survive, the rate of decomposition will increase in moist conditions.
  • However, if the soil becomes waterlogged then the oxygen levels will fall, which will decrease the rate of decomposition.
• Compost - mixture of decaying organic material that is used as fertiliser.
• Biogas;

  • Microorganisms can decompose things without oxygen - called anaerobic decay.
  • This produces methane.
  • When methane is combusted it releases lots of energy.
• Biogas generators;

  • Are large containers where plant and animal waste is left to decay anaerobically.
  • Once the biogas is extracted there is a sludgy materials left over, which has a high density of use minerals. So it can be used as fertiliser.