The Living Soil

05/14/2012 15:31

            All the new growth around us in the spring is cause for wonder. And the soil on which all this beautiful green depends is a wonder itself.

            Usually found in topsoil, organic matter is the storehouse for the energy and nutrients used by plants and other living organisms. Organic matter includes living organisms, dead plants and residue, decomposing plant and animal material, and humus (material not readily decomposed).

            In the organic matter of the soil is an incredible diversity of millions of living organisms and many species from one-celled bacteria to visible worms and insects. This is a community of living things that spend all or part of their life in the soil. As these organisms eat, grow, and move through the soil, they make it possible to have clean water, clean air, healthy plants, and moderated waterflow. Composting is a great way to experience soil organisms in action, breaking down manure on the farm or leaves in the yard.

            Living things are not distributed equally through the soil. They live around roots, in plant litter, on humus, on the surface of soil aggregates (many small particles of soil held together in a small mass), and in the spaces between soil aggregates. The activities of soil organisms are also seasonal.

            Land management practices can change the complexity and heath of the soil community, for example: field crops with more rotations of different crops will provide for more types of organisms; a field broken up by grassed waterways, terraces, or field border strips will provide more habitat for arthropods; reducing the use of pesticides generally increases the diversity in the soil community; reducing tillage makes earthworms and arthropods more plentiful over time.           

            Land that is managed for good soil health with a diversity of living organisms will protect all resources, including soil, water, air, plants, animals, and humans. The community of living things in the healthy soil serves a good land manager by:

  • Efficiently storing and cycling nutrients thereby reducing fertilizer requirements.
  • Holding nitrogen in the rooting zone.
  • Effectively degrading pollution and preserving water quality.
  • Enhancing soil structure so more water soaks into the soil.
  • Stabilizing the soil structure so less topsoil is lost to water and wind.
  • Suppressing disease with a healthy soil food web.

            All plants depend on the food web of the community of living organisms in the soil for the food and nutrients they need to grow. We can learn to appreciate and learn better ways to care for the life under our feet. Call on UI Extension Master Gardeners and your county Soil and Water Conservation District for help.  

Information for this article is from the Soil and Water Conservation Society (SWCS). 2000. Soil Biology Primer. Rev. ed. Ankeny, Iowa: Soil and Water Conservation Society. Search ‘Soil Biology Primer.”

Della Moen, Earth Team Volunteer, NRCS/Stephenson Soil and Water Conservation District, an equal opportunity provider and employer, 05/09/12 (for publication on 05/12/12 in the Journal- Standard, Freeport, Illinois)  Della can be reached at