Soil Food Web


The health of the soil is dependent on many elements that make up soil. A healthy soil will be of a good structure to hold air and water, rich in nutrients and thriving with life. In a handful of healthy garden soil, there are more than a billion bacteria of several hundred kinds, about ten thousand protozoa, fungi, and several nematodes and microarthropods. These, together form the soil food web. These are the decomposers and nature’s solution to recycling the biological energy on earth.

Scientifically, the study of soil life is still new and the majority of these organisms have yet to be identified and named. What is known so far is the relationships the soil microorganisms share with the plants and some of the ways in which they interact with their environment.


Plant-microorganism relationship

Plants and soil life have a very strong symbiotic relationship. They depend on each other for their survival. Up to 30% of the food that plants produce during photosynthesis is exuded out of their roots into the soil to feed the soil life, which in turn decompose organic matter and release plant-available nutrients. Plants depend on this plant-microbial bridge for up to 85-90% of the nutrients and trace elements they require for healthy growth. The microorganisms also extend the effective root system of the plants accessing water and nutrients from a wider network below the soil.



Bacteria and Fungi decompose all the organic matter in the soil to release plant-available nutrients and create humus. The higher trophic levels in the soil food web feed on Bacteria and Fungi and also help release the energy stored in their bodies.

There are also studies that confirm that the soil food web helps decompose toxins in the soil.



Bacteria and fungi release organic acids that mineralize rock particles in the soil thus continuously weathering rock, building soil and adding minerals to it.



When bacteria grow, they produce glues in which they bind soil and mineral particles, organic matter etc., forming micro-aggregates. Fungi, with their long strands and webs, bind these micro-aggregates together to form macroaggregates.

Thus, bacteria become the bricks and fungi become the mortar of a good soil structure.

Good structure will help retain water in the soil reducing irrigation needs and allow plant roots to go deeper making them healthier.



A diverse set of aerobic microbes in the soil will outcompete disease-causing bacteria and fungi.



To maintain a healthy soil food web, it needs to be kept fed. This can be done by:

  1. Ensuring no land is left fallow
  2. Growing a diversity of plants (diversity above correlates to diversity below)
  3. Adding compost
  4. Adding mulch and organic matter



Some soil scientists believe that it takes over a thousand years for 1 inch of topsoil soil to form. While this may be true in natural systems, where soil formation and erosion balance each other, the process of topsoil formation can be accelerated dramatically by adding organic matter and diversity of microorganisms.
A healthy soil food web sequesters atmospheric carbon (gas) and sugars exuded by the roots (liquid) and preserve it in the soil as humus (solid).

Humus is a highly complex form of carbon linked to other elements and nutrients. It is a result of repeated decomposition of organic matter, where, while some carbon is reduced into simpler forms (catabolic process), some of it keeps on building into more and more complex forms (anabolic process). Humus, due to its low specific weight and high surface area, builds good soil structure and increases its capacity to hold air, water, and nutrients.




The scientific understanding of how the soil food web works and how we can work with it to create healthy ecosystems comes from decades of research and experimentation of Dr. Elaine Ingham, an American soil microbiologist.


Bacterial and fungal composts