The Soil Food Web & The Relationship to Healthy Soil

To support sustainability, a good foundation is necessary.  Just as important as a well constructed building foundation, the soil food web is the foundation that creates the soils needed to support healthy, sustainable plant life.

Good soils are teeming with life, from earthworms to centipedes and ants, there is a world of soil organisms such as fungi and bacteria in which every organism needs energy to survive.  They derive this energy from nitrogen and sulfur and carbon that is produced from plants and waste products produced by other organisms.  The soil food web, beneath and above the soil is simple eat and be eaten existence.  Organic matter produced by healthy plants and root systems create organic matter that is turned into bacteria (subsurface) while fungi is being created closer to the soil surface.  In a cross-linked soil food web, root and fungal feeding nematodes are then preyed upon by birds which in turn are preyed upon by larger animals.  To simplify, it always starts with the plant.

Plants secrete chemicals that are important to the soil’s condition, through photosynthesis in the leaves and these secretions are referred to as 'root exudates'.  These carbohydrates exudated by roots grow beneficial bacteria and living fungi which commences the food web.  These beneficial bacteria and fungi are natural fertilizers for healthy plants and are spread by nematodes by eating the bacteria and fungi, digest what they need to survive and excrete excess carbon as waste.

As we gardeners all know, not all soil bacteria and fungi is beneficial and many cause plant diseases.  Having good soil food web containing a large, diverse population of different species will help control theses non-beneficial troublemakers.  This healthy soil food web will keep these pathogens in check and in some instances to their deaths.  Mycorrhizal fungi is a special soil fungi, interacting with roots, producing nutrients such as water, nitrogen and phosphorous.

The importance of understanding the soil food web, the foundation of good soil, is to also understand the negative impacts on the soil food web.  Chemical fertilizers, pesticides and insecticides affect the soil food web in a negative way, toxic to some and chasing others away.  You have now started altering the soil food web as you will have to continue to use chemical fertilizers and pesticides as plants microbial method of obtaining nutrients has been affected by reducing the natural fungi and bacteria and chasing away a major contributor, the earthworm. 

The living organisms within the soil food web will be continuously at work, building defenses against pests and disease, creating soils that drain well and pathways for oxygen and carbon dioxide.  By employing soil food web knowledge, you can reduce / eliminate the use of commercial chemicals and fertilizers, improve your soils overall health and usefulness and start building a sustainable foundation.

Next blog release, we will discuss the soil food web and its important relationship with compost tea, mycorrhizal and maintaining trees, shrubs and perennials.