Parent material would be a sterile accumulation of mineral particles without biological activities
It is the growth and decay of plants, animals and micro-organisms, which makes the soil a dynamic, distinctive substance. These organisms interact with the minerals, water and air to create a material in which all four are inter-connected. The initial plant life accelerates soil formation as the plants themselves physically and chemically modify the particles, exudates from the plants provide substrates for microbial metabolism and, when the plants die, they contribute further organic matter to the soil. Plant roots can also be important in breaking down rocks, and organisms such as Earthworms are vital in mixing the different components up.
How do soils and biomass interact?