Worms eat dead and decaying plant (and animal, and bacterial, and other organic) remains. Anything that was once part of a plant but is now decaying will be eaten by worms. 'Decaying' means being invaded and digested by bacteria and moulds: it is these moulds that attract the worms. Worms also swallow large amounts of soil and digest the moulds, bacteria and plant remains in the soil. The faeces of earthworms contains bacteria, humus, particles of rock and mineral salts.
There are hundreds of species of worms in the soil, and each one has a range of temperature, humidity and soil type which it prefers.
Vermiculture is a system of using Eisenia foetida to digest food waste; The resulting worm casts (faeces) are rich in plant nutrients (mineral salts) and are used as a fertiliser or soil additive.
The special worms are kept in a bed of bran, within a warm, ventilated bin or container, to which is added food waste. The worms swallow the decaying food waste and egest nutrient rich faeces. If the temperature falls, or the food supply dwindles, the worms die and their eggs remain dormant until the temperature rises again and a food supply is restored. Fresh food (kitchen waste) is added to the top of the mix and the worms move upward toward it.
Eventually the worm casts are separated out, the worms and food waste are returned to the bin and the casts are used in the garden as a slow release fertiliser.
The worms, the bran and the bins are all available commercially. The food waste comes from the kitchen. Domesticated livestock, whether cows, dogs or earthworms, need maintenance.
A heap of plant and food waste on the soil in the garden will not attract E. foetida (the ground is too cold: indeed, E. foetida added to an outdoor heap will just die), but it will attract Allolobophora species and Lumbricus species of earthworm. It will also attract snails, woodlice and centipedes, all of which will eat the decaying waste and leave their droppings: all excellent sources of humus and minerals: slow-release fertilizer!
If a heap of kitchen waste on a vegetable bed looks unsightly, it can be covered with a layer of grass clippings; that will accelerate the decay and contribute to the compost.
If this 'compost heap' is built in the middle of a vegetable bed the finished compost can simply be raked across the surface of the bed ready for the next crop.
Vermiculture is a triumph of marketing over biology.
