Decomposition is the process of breaking down of complex organic matter with the help of decomposers into smaller inorganic raw material such as CO₂, H₂O, and other nutrients. It constitutes of various processes:

1. Fragmentation: The breakdown of detritus (Organic matter) into smaller pieces by the action of detritivores (earthworms).

2. Leaching: The water-soluble nutrients move down into the layers of soil and get locked as unavailable salts.

3. Catabolism: Further the detritus is degraded into smaller pieces by bacteria and fungi through various enzymes.

4. Humification: Humification leads to the formation of a dark coloured colloidal substance called humus, which acts as reservoir of nutrients for plants.

5. Mineralization: The process of releasing inorganic nutrients from the humus in the soil is done by microbes and this process is known as mineralization

Decomposition thus leads to the production of a dark coloured, nutrient-rich substance called humus. Degradation of humus releases inorganic raw materials such as CO₂,water, and other nutrient in the soil.