Dead and decaying plant and animal remains are an important component of individual ecosystems. In many ecosystems dead organic matter, made up of surface litter and soil humus, greatly exceeds the living biomass in volume or weight. This is an important component of an ecosystem as the dead organic matter contains the nutrients that are being recycled in the ecosystem. These nutrients are returned to the soil by the process of decomposition, which is carried out by the soil micro-organisms. These nutrients are then ready to be taken up by the plants of the ecosystem and from there they are cycled to the animals. When the plants and animals die, the nutrients are again part of the dead organic matter and are ready to be cycled again through the ecosystem.

   Various types of organisms and microorganisms live in soil. Moles, groundhogs, prarie dogs, and others of moderate size churn up the soil while making tunnels and burrows. Some microorganisms also burrow and channel through soil, which improves soil structure and aggregation, while other microorganisms have the ability to break down resistant organic matter such as lignin, toxins, and pesticides. Microorganisms also have the ability to protect plants from antagonistic pathogens and some can dissolve minerals, making nutrients available to plants.

             Earthworms are like "Nature's Tillers". They incorporate dead organic    matter into soil, ingest it, and excrete the nutrient rich casts on to and in soil. Earthworms improve aeration, water infiltration, drainage, and they enhance nutrient availability and cycling. Dung Beetles and Termites also incorporate dead organic matter into soil. 

   Fungi are able to break down resistant materials such as cellulose, gums, and lignin. They dominate in acidic, sandy soils and in fresh organic matter.

             Actinomycetes also are able to decompose resistant substances in soil. One type, Frankia, help plants get nutrients needed from the air by breaking triple bonded nitrogen down into ammonium that plants can use. Antibiotics are made from soil Actinomycetes.

     Bacteria decompose a wider range of earth material than any other microbe group. Heterotrophs gain their energy and Carbon from other organisms, while Autotrophs synthesize their own energy from light or by chemical oxidation. Some bacteria can fix nitrogen in to forms plants can use.

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