The process of breaking down complex organic matter into inorganic substances like carbondioxide,water and nutrient is called decomposition. The raw materials for decomposition is called detritus.They are dead remains of plants and animals.
Steps of decomposition :
Fragmentation : Breakdown of detritus into smaller particles.e.g.,earthworm.
Leaching : Water soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts.
Catabolism : Bacterial and fungal enzymes degrade detritus into simpler inorganic substances.
Humification : It leads to the accumulation of a dark colored amorphous substance called humus that is highly resistant to microbial action and undergoes decomposition at an extremely slow rate.
Mineralization : The humus is further degraded by some microbes and release inorganic substances by this process.