Even seemingly simple tasks, like raising the humble earthworm, can be done in more ways than one, however all variations must follow certain basic principles.
In a video from Bangladesh, villagers show the audience how to raise earthworms in cement rings, sunk into the soil. The floor is covered with a sheet of plastic to keep the worms from escaping. The worms are fed on chunks of banana corm and the ring is covered to keep out the rain, but still retain some moisture.
My grandfather used to raise worms in a pressed-board box on his back porch. He fed them on strips of newspaper and used coffee grounds. So I knew that there was more than one way to raise worms, but I didn’t quite realise how many options there were, until I saw two small, family firms in Cochabamba, Bolivia at an agricultural fair. Both firms raise earthworms and sell the worms, the humus they make, and the excess moisture collected in the process (to use as fertilizer—applied on leaves or the soil).
One company experimented with various types of containers. The worms died in plastic ones, but they thrived inside of aluminum cylinders, wrapped in foam (to keep them cool) inside of a metal barrel. A screened base with a tray collects the humus, while worm food (especially composted cow manure) is loaded into the top of the barrel.
A second company had a different devise. They use stacks of plastic-covered wooden trays on a slight slant, and they feed the earthworms corn plant residues, semi-composed cow manure, and kitchen scraps. Earthworms have their favourite foods. “Earthworms like all of the cucurbits (like squash), but nothing sour,” explained Silvio Gutiérrez and his wife, the company owners. “They don’t like citrus at all.” Earthworms will eat paper, but they prefer egg cartons.
So here we have a Bangladeshi cement ring, a Bolivian barrel and a set of wooden trays. It seems like a lot of different ways to raise worms, which is an important topic, because the night-crawlers, as my grandfather used to call them, help to enrich the compost, stabilise it and they improve the soil with the beneficial micro-organisms they release.
All of these worm brooders share certain core principles. The worms are kept cool, not allowed to escape, and are fed on organic matter (depending on what is abundant locally) and the earthworms are not allowed to get too dry or too moist.
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