What is the Soil Food Web?

The soil food web is essentially a healthy and functional soil that is living with bacteria, algae, fungi, and protozoa, as well as more complex nematodes and micro-arthropods — and the sometimes visible earthworms, insects and small vertebrates. The soil food web is living soil and not dead soil, aka dirt.

These living organisms in the soil can convert silt, clay, sand, rocks and organic matter into available nutrients for our trees. Trees will also help feed these organisms with exudates (soluble sugars, amino acids and other compounds secreted by roots; these are produced from the sun and photosynthesis). Actually the trees and plants can send signals to these living organisms in the soil that indicate the nutrients the trees and plants need. 

So what does a healthy soil do?

• Retains nutrients
• Increases plant available nutrients
• Suppresses insects and diseases on trees and plants by making them more healthy to defend against diseases and pests
• Helps decompose some toxins that may be in the soil or make them less biologically available
• Builds soil structure
• Increases water holding capacity in your soil
• Reduces run-off from rain or irrigation
• Increases in carbon stored in soil (Google it! It’s very interesting and promising science.)

What does dead or unhealthy soil, aka dirt, look like or do?

• Exposed bare soil is never good
• Erosion is more likely to occur with dead soil
• Trees become dependent on inorganic fertilizer inputs in dead or unhealthy soils
• Trees may show leaf discoloration, smaller leaf size, short internodal growth
• Trees and more likely to have inspect and disease issues 

Above picture: four-foot rod easily pushed into healthy soil

What does healthy soil look like?

• The soil should smell good, should smell earthy and maybe like mushrooms.
• Soil shouldn’t be void of smells or have a very bad smell (sewer smelling is bad).
• You may see earthworms in healthy living soil
• Should be dark; the soil should be glued together and holding on to roots
• you should see other living organisms in the soil.

Healthy soil EQUALS healthy tree… similarly like a healthy gut EQUALS healthy human

What can you do to help your soil?  

• Stop tilling your yard or garden.  Actually tilling your yard is likely to damage a lot of small roots adjacent to mature trees.
• There should be no exposed or bare soil in your yard; always mulch or plant cover plants in your yard or garden.
• Increase the diversity in your yard (not just one tree and one species of grass)
• Increase organic matter in your soil
• Reduce compaction in your soil: so do not aerate or move when the soil is wet; do not drive on your soil with cars or trucks, especially when the soil is wet.

See the below links if you’re interested in more info from the U.S. Department of Agriculture on the Soil Food Web or if you’d like a digital copy of the Soil Biology Primer book.