The Scale of Soil Life
Soil Biology / Field Reference 01
The Scale of Soil Life
Everything below is drawn at true relative size. Zoom out from a virus to an earthworm and the whole soil food web passes through one frame, across six orders of magnitude.
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Why size runs the system
Body size decides who eats whom and where anything can physically go. A bacterium fits inside a pore a nematode will never enter, and a fungal hypha crosses gaps that stop a root hair cold. The soil food web is a size ladder before it is anything else.
The nutrient release step
Bacteria hold nitrogen at a much tighter carbon to nitrogen ratio than the protozoa and nematodes that graze them. That mismatch is the point. Every time a predator eats a bacterium, surplus nitrogen is released as plant available ammonium, right at the root.
Reading the frame
Sizes shown are typical field values, not maximums. Fungal hyphae and root hairs are measured across the tube, since length is effectively unbounded. Mineral particles and a few everyday objects are included as anchors.