Descriptions of earthworms castings (their poop) as nature's black gold pop up more and more these days, but what is it really about the manure of these little slimy animals that makes it so precious?
It has been known for a long time that healthy soils contain an abundance of earthworms, but their full significance has not been recognized until relatively recently. They help with the decomposition and mixing of organic matter in the soil, they aerate and loosen it, but perhaps their most important function is that they kill pathogenic organisms and add beneficial microorganisms to our soils. Their digestive system and slimy skin is covered with hosts of these beneficial organisms, bacteria, protozoa, nematodes and even fungal hyphae, which through competition, inhibition and consumption, eliminate disease causing organisms. They need the right conditions to do their work, which includes a fully aerobic environment, not too moist, not too dry, and an abundance of organic matter. Worms ingest and shred plant material as they eat the microbes growing on them. Once in their digestive system, the "bad guys" (pathogenic organisms) are eliminated and "good guys" (beneficials) are added to their waste. As all the members of the soil food web, prey and predator, are present in their castings, we call it biologically complete. All members and levels of this 'soil-food-web' have an important function and this is why adding worm castings to our soils is so beneficial for our plants and our own health.
