Compost worms don’t work alone. There is a process that’s nothing short of magic that happens in the dark moist soil of the worms bins. There is an orchestrated process unfolding as a result of the concerted effort among a group of active organisms and microorganisms. Worms, bacteria, and a host of microorganisms work collectively to break down organic material leaving behind a pile of castings that are nutrient rich and often referred to as “black gold”.
The mutually beneficial relationship
Compost worms ingest soil that contains a plethora of organic particles, bacteria, fungi, and other micro-organisms. It mixes with mucus and moisture which neutralizes the pH. This triggers a bloom in certain types of bacteria, specifically Rhizobiales, which aid in the process. Nutrients are released in the process and reabsorbed by the worm along with much of the moisture.
The end product is called vermicast, or worm casting, and are simply worm poop loaded with nutrients, organic particles, and a flourishing community of bacteria and fungi that are perfectly suited to plant development. It’s no wonder gardeners are so interested in using worm castings to amend soil, fertilize crops, and aid in the suppression of plant pests and disease.
The role of micro-organisms
The beneficial, and mutualistic nature of worm/bacteria relationship is anything but accidental. Compost worms have a very basic digestive system. The bacteria in the soil do most of the heavy lifting by breaking organic matter down enough for the worm to capitalize on it. In exchange, the worm provides a perfectly anaerobic environment in which the bacteria can thrive.
But the value of the bacteria is relegated to just the environment inside the worm. That’s just half of the story. Once the composting worm expels the castings, and along with them a host of bacteria, the microorganisms are not in a perfect position to start the process all over again. They begin to break down organic material and in time will be once again ingested by worms to cater again to the worm’s need from the inside.
The increase in nutrient value of castings
Just like we shared before, soil that a worm digests is suddenly 5 times richer in nitrogen, 10 times richer in potassium, has 7 times more phosphate, 1.5 times as much calcium and 3 times the magnesium.
But don’t forget about the increased biological activity, if you’d like to dig deeper into the specifics of the relationship between worms and bacteria, you should reference this article on MicrobeWiki.