Worm farming basics

Vermicomposting uses earthworms to create a mixture of decomposing vegetable or food waste, bedding materials and vermicast (worm castings).

As noted, worm castings are the end-product of earthworms’ digestion of organic matter. They contain lower contaminant levels but more concentrated nutrients than are present in the organic materials before vermicomposting.

Eisenia fetida and E. andrei are the most common species used. DNA research at North-West University found E. andrei in more than 10 worm farms in four provinces in South Africa.

The genus Eisenia is from the Northern Hemisphere but is generally considered non-invasive. It is epigeic, which means that it is found near the soil surface in compost or leaf litter.

Large-scale vermicomposting is practised around the world. Some vermiculture systems use windrows, which consists of bedding materials for the earthworms to live in. They are topped up regularly with organic material.

For smaller scale vermicomposting, a large variety of bins are commercially available. Alternatively, other containers can be adapted; examples are a ‘tower’ of old car tyres, an old cooler box, or a large bin with a lid and drainage hole/tap.

Worms prefer organic materials such as fruit and vegetable scraps, avocado pips and skins, egg shells, tea bags, paper scraps, bread crusts, kraal manure, grass cuttings and leaves. They should not be fed animal protein, milk products, oil, fat, acidic items such as onion, pineapple, lemon, garlic or chilli, or nonbiodegradable and domestic waste.

“A worm farm works well with a little care and maintenance,” says Patrick Dowling of the Earthworm Interest Group of Southern Africa (eigsa.co.za). “It’s cheap, and the high-value components – the worms – replicate themselves readily, so starting small is no problem.

“The more you feed your Eisenia worms, the faster they multiply, which means you can share them with friends and colleagues who want to start their own worm farms.”

If you are interested in worm farming, the Rhodes University website ru.ac.za/environment/resources/ wormfarming is a good starting point.