An acre of living topsoil contains approximately 900 pounds of earthworms, 2,400 pounds of fungi, 1,500 pounds of bacteria, 133 pounds of protozoa, 890 pounds of arthropods and algae, and even small mammals in some cases. Soil can be viewed as a living community rather than an inert body. Soil organic matter also contains dead organisms, plant matter, and other organic materials in various phases of decomposition. Native soils are covered with a layer of plant litter and/or growing plants throughout the year. Beneath the surface litter, a rich complex of soil organisms decomposes plant residue and dead roots and releases their stored nutrients slowly over time.

In fact, topsoil is the most biologically diverse part of the earth. The type of living soil required to support humans now and far into the future will be balanced in nutrients and high in humus, with a broad diversity of soil organisms. It will produce crops with minimal weed, disease, and insect pressure. To accomplish this, the need is to work with the natural processes and optimize those functions to sustain all farming.

Soil-dwelling organisms release bound-up minerals, and convert them into plant-available form. The organisms recycle nutrients again and again with the death and decay of each new generation of plants. There are many different types of creatures that live on or in the topsoil. Each has a role to play. These organisms will work for the farmer’s benefit if managed correctly for their survival. While a great variety of organisms contribute to soil fertility, earthworms, arthropods, and the various microorganisms merit particular attention.