The physical and chemical breakdown of detritus or dead organic matter (i.e., dead plant, animal, and microbial material) is called - Decomposition
Decomposition results from three types of processes with different controls and consequences., They are,
Leaching by water transfers soluble materials away from decomposing organic matter into the soil matrix. These soluble materials are absorbed by organisms, react with the mineral phase of the soil, or are lost from the system in solution.
Fragmentation by soil animals breaks large pieces of organic matter into smaller ones, which provide a food source for soil animals and create fresh surfaces for microbial colonization. Soil animals also mix the decomposing organic matter into the soil.
Chemical alteration of dead organic matter is primarily a consequence of the activity of bacteria and fungi, although some chemical reactions also occur spontaneously in the soil without microbial mediation.
