Concept

Soil food web

The interconnected community of organisms living in healthy soil — bacteria, fungi, protozoa, nematodes, arthropods, earthworms — that together cycle nutrients, build structure, and feed plants. Articulated as a unified concept by USDA soil microbiologist Elaine Ingham (b. 1951) and others; the framework underlies modern soil-health practice. A teaspoon of healthy soil contains more microbial individuals than there are humans on Earth. The food web's collapse under tillage and chemical agriculture, and its restoration under cover-cropping, composting, and minimal disturbance, is the mechanism beneath every regenerative-agriculture outcome.

The food web in soil

The trophic structure that ecologists describe in forests and oceans also operates underground:

Primary producers — plants. Roots exude sugars, amino acids, and other carbon-rich compounds into the rhizosphere — feeding the rest of the web.
Decomposers — bacteria and fungi consume root exudates, dead plant matter, and each other. Most numerous; foundational to all subsequent levels.
First-level consumers — protozoa and nematodes that eat bacteria and fungi. They release nitrogen the bacteria/fungi had immobilized, in plant-available form.
Higher consumers — predatory nematodes, mites, springtails, and other microarthropods that eat the first-level consumers.
Engineers — earthworms, ants, larger arthropods that move organic matter and build soil structure.

Numbers

A teaspoon of healthy agricultural soil contains:

Hundreds of millions to billions of bacterial individuals
Tens of meters of fungal hyphae
Tens of thousands of protozoa
Dozens to hundreds of nematodes
Hundreds of microarthropods if you scale up to a cup

A teaspoon of conventionally-tilled-and-fertilized agricultural soil typically holds a small fraction of these — particularly fungi, which tillage disrupts severely.

The Ingham framework

USDA soil microbiologist Elaine Ingham developed the synthesis that pulled [[soil|the soil]]-food-web concept into agricultural practice during the 1990s and 2000s. Her Soil Foodweb Inc. consultancy and training programs introduced thousands of farmers to the diagnostic question: what is the bacterial-to-fungal ratio of your soil, and is it appropriate to what you’re trying to grow? Different crops and ecosystems prefer different ratios — annual vegetables ~1:1, mature forest 1:100+ fungal-dominant.

Why it matters

Every regenerative-agriculture outcome — soil-building, water infiltration, nutrient cycling, plant health, drought resilience — is the visible expression of [[soil|the soil]] food web doing its work. The practices of [[regenerative-agriculture|regenerative agriculture]] (no-till, cover cropping, composting, integrating livestock, perennials) are all, mechanistically, ways of feeding and protecting the soil food web. Industrial agriculture, by contrast, replaces the food web’s services with synthetic inputs and disturbs it through tillage and chemicals.

Sources

Teaming with Microbes, Jeff Lowenfels and Wayne Lewis (Timber Press, multiple editions)
Elaine Ingham / Soil Foodweb Inc. published materials
USDA NRCS soil-health technical materials

Rooted in life.

What links here, and how

Inbound connections from across the wiki, grouped by lens and by relationship. These appear automatically — every entity page declares what it links to, and that data populates here on the targets.

Scientific

shares approach with

Carbon cycle soil organic-matter cycling — driven by the soil food web — is a major terrestrial carbon-cycle pathway
Hugelkultur the buried wood becomes a long-term substrate for fungal-dominated soil biology

member of

Earthworm earthworms are the principal macro-fauna of the temperate soil food web
Garden Spider garden spiders occupy the above-ground top-predator role in garden invertebrate webs
Ground Beetle ground beetles are top macro-predators on the soil surface, regulating populations of smaller invertebrate fauna
Toad toads occupy the top-vertebrate-predator role in garden invertebrate food webs

substrate of

Nitrogen cycle nitrogen cycling — fixation, mineralization, immobilization, mineralization again — is largely the work of the soil food web

subset of

Rhizosphere the rhizosphere is the most active subset of the broader soil food web — the plant-mediated zone where biology is densest

parallels

Soil Microbiome the soil-microbiome and soil-food-web frameworks describe substantially overlapping subjects from different angles — microbiome focuses on the microbial community structure and metabolism; food-web focuses on the trophic relationships and energy flow

Practical

counterpart to

Hydroponics hydroponics bypasses the soil food web entirely — the nutrient cycling that fungi, bacteria, and soil fauna do in nature is replaced by chemistry and pumps. Different system, different failure modes

10 inbound links · 4 outbound