For more information, please see:
Soil Biology Primer, by Dr. Elaine Ingham
NRCS Soil Biology, By Andrew R. Moldenke, Oregon State University
Micro and Macro-Arthropods
Many bugs, known as arthropods, make their home in the soil. Nearly every soil is home to many different arthropod species. Certain row-crop soils contain several dozen species of arthropods in a square mile. Several thousand different species may live in a square mile of forest soil.
The majority of Macro(Large) Arthropods can be considered shredders. Extremely useful as they are in the ecosystem, Shredders chew up dead plant matter as they eat bacteria and fungi on the surface of the plant matter. By doing this, they take in and excrete valuable soil nutrients, and become vessels for entomopathogenic fungi as well as certain stored resources.
By breaking down the larger pieces of decomposing material on the soil surface, Shredders make decomposition short work for bacteria and fungus within the soil, while also stimulating the growth of microbial and bacterial populations.
Predators and micropredators can be either generalists, feeding on many different prey types, or specialists, hunting only a single prey type. Predators include centipedes, spiders, ground-beetles, scorpions, skunk-spiders, pseudoscorpions, ants, and some mites. Many predators eat crop pests, and some, such as beetles and parasitic wasps, have been developed for use as commercial biocontrols.