Dead organic matter from the plants in the form of litter and root exudate (including acids, sugars, polysaccharides and ectoenzymes) and dead roots are processed by living organisms in the soils.
For example, earthworms may substantially improve soil condition in newly formed soils, such as in post mining sites. In the same time, earthworms can also cause severe negative impacts by bringing invasive exotic species to the ecosystem.
Plants, animals and micro-organisms (fungi and bacteria) all affect soil formation by producing or contributing to humus production. The amount of humus in a soil is a result of how much plant material has been incorporated into it.
