Beneficial Microbes & Worm Castings
Worm castings are not just nutrients—they’re living biological inoculants. Worm castings create an ideal environment for beneficial microbes to thrive. Worm castings are a microbial powerhouse that build living soil, improve plant resilience, and create a natural cycle of fertility. When checking worm casting samples I look for diversity in the microbiology. This includes Amoeba, Nematodes, Fungal Hyphae and Bacteria.
Images of Amoeba (Protozoa) found in Worm Castings.
These images are at 400x magnification.
Nematodes can be categorised as bacterial-feeders, fungal-feeders, predators, omnivores, plant-parasites. The ones we do not want are the plant-parasites or root feeders.
Bacterial-feeding nematodes (often called bacterivorous nematodes) keep bacterial populations balanced, unlock nutrients for plants, boost nitrogen cycling, and maintain soil fertility.
Fungal-feeding nematodes (also called fungivorous nematodes) regulate fungal populations, aid nutrient cycling.
Predatory nematodes (also called carnivorous nematodes). These are Free-living nematodes that hunt and feed on other soil organisms such as other nematodes (including plant parasites), Protozoa and small soil invertebrates (mites, rotifers, larvae). Unlike bacterivores or fungivores, they have large, toothed or spear-like mouthparts adapted to grab, pierce, or suck out prey. They release nutrients from their prey that plants can use.
Omnivorous nematodes are free-living soil nematodes with flexible feeding habits. They can feed on multiple food sources depending on availability. Food sources include bacteria, fungi, protozoa, other nematodes and organic debris. They release nitrogen and other plant available nutrients.
Images of bacterial feeding nematodes.
The mouth parts indicate that this is a predatory nematode.
Fungal hyphae
When fungal hyphae are present in worm castings, they add extra benefits. Hyphae break down complex organic matter (like lignin, cellulose, chitin) that bacteria can’t easily digest. They make slow-release nutrients available to plants over time, especially phosphorus and micronutrients. Fungal hyphae form networks that bind soil particles into aggregates. This improves aeration, drainage, and water-holding capacity of soil. fungal hyphae in worm castings enhance nutrient release, improve soil structure, protect plants from disease, and foster healthier root systems.
Recommended learning and resources.
If you want to learn more about beneficial microbes, I recommend that you visit Sandra Tuszynska’s YouTube series or the website for the Soil Restoration Course.
Sandra is an Australian based agricultural scientist who specialises in soil microbiology.