Decomposition is the breakdown of dead organisms and waste material by decomposing microorganisms, such as bacteria and fungi. This process plays an important role in the cycling of elements, such as carbon and mineral ions.

Decomposition typically begins soon after an organism dies, as bacteria and other decomposers begin to consume the organic matter. As they break down the matter, they release gases such as carbon dioxide, methane, and water vapour. As there is only a fixed amount of elements on Earth, decomposition is important for returning materials to the environment.

In addition to releasing gases, decomposition also helps to enrich the soil. As decomposers break down organic matter, they release nutrients like mineral ions, which can be absorbed by plants and used for growth. This makes decomposition an important process for maintaining the fertility of the soil and supporting the growth of plants.

Factors Affecting the Rate of Decay

The rate of decay is the speed at which decomposers break down biological material. There are three main conditions that increase the rate of decomposition:

  • Temperature
  • Water
  • Availability of Oxygen


Decomposers use enzymes to break down biological material and these enzymes work faster in warm conditions. So, decay takes place at a faster rate in warm conditions.

  • If the temperature is too high, the enzymes will denature (lose their function), which will decrease the rate of decay.
  • If the temperature is too low, the enzymes will work much slower, which will decrease the rate of decay. This is why food is put in the fridge or freezer to slow down the rate of decay.


As water is essential for many biological processes, decomposers require it to survive. The decomposers secrete enzymes onto decaying biological matter and absorb the dissolved products. Without water, this process cannot take place.

So, as the amount of water available decreases, the rate of decay also decreases.

Availability of Oxygen

Decomposers carry out aerobic respiration, which requires a good supply of oxygen. Without oxygen, they will not survive. This is why we seal food with cling film and food bags to reduce the availability of oxygen and slow down decay.

So as the availability of oxygen increases, the rate of decay also increases.

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