Before composting can be understood as more than yard waste management, it is necessary to have a working model of what lives in healthy soil and what each organism does. This part of the course covers that vocabulary — the cast of organisms that actually make soil work, and the single most important conceptual tool for a homesteader: the bacterial-to-fungal ratio.
The Principal Organisms
A single teaspoon of healthy soil holds more microorganisms than there are people on the planet. They don't all do the same job. Here are the ones that matter most for a homesteader trying to grow nutrient-dense food.
| Organism | Primary Function | Key Notes |
|---|---|---|
| Bacteria | Nitrogen cycling, decomposition of simple sugars and proteins | Most abundant in disturbed, tilled, or high-N soils |
| Fungi (saprophytic) | Decompose lignin and cellulose; build humus; create soil aggregates | Dominant in old-growth, undisturbed, carbon-rich soils |
| Mycorrhizal Fungi | Extend plant root reach 100-1000x; trade minerals for plant sugars | Critical for mineral density; destroyed by tillage and phosphate fertilizers |
| Protozoa (amoeba, flagellates) | Eat bacteria; release excess nitrogen as plant-available NH4+ | Primary nitrogen cycle regulators — the 'slow-release' mechanism |
| Nematodes | Bacterivores and fungivores release nutrients; predatory types control populations | Indicator species for food web balance |
| Arthropods (springtails, mites) | Fragment organic matter; inoculate compost with microbes as they move | Shred large particles into bacterial/fungal substrate |
| Earthworms | Ingest soil + organic matter; cast material is premier plant food | Castings contain 5x more N, 7x more P, 11x more K than surrounding soil |
Bacterial vs. Fungal Dominance
This is the most important conceptual tool for a homesteader. Different plants prefer different bacterial-to-fungal (B:F) ratios in the soil, and your management choices directly shift this ratio. Tillage, annual vegetable crops, and fresh manure push soil bacterial. Woodchip mulch, perennial plantings, and low disturbance push it fungal. Both are "healthy" — but healthy for different plants.
| Plant / Habitat Type | Preferred B:F Ratio |
|---|---|
| Annual vegetables, herbs | Bacterial-dominant (B:F 1:1 to 5:1) |
| Perennial grasses, meadow plants | Transitional (B:F 1:1) |
| Shrubs, orchard trees | Fungal-leaning (B:F 1:2 to 1:5) |
| Old-growth forest, conifers | Highly fungal (B:F 1:100+) |
| Bare, tilled, or compacted soil | Bacterially collapsed (B:F 100:1+) |
Practical takeaway: Compost for vegetables = hot compost, high N, bacterial. Compost for fruit trees and perennial beds = cold, slow, woody, high C, fungal. Different piles for different zones. We cover how to build each in Part 2: Living Compost.
Feed the Community
Now that the cast of soil organisms is clear, the next step is learning to build compost that inoculates them rather than just fertilizes them. Part 2 covers the two composting philosophies, the C:N ratio, and a step-by-step hot compost protocol.
The Living Soil Course · Part 1 of 6