Tuesday, February 12, 2008

Worm Composting

Three new, concrete composting bins have been constructed on the farm. They illustrate similar designs being used successfully in places such as Nicaragua. In this system, worms are utilized to process organic inputs comprised of manure or vegetative waste (e.g. weeds/kitchen scraps).
Each bin has a cement bottom to prevent incursion of roots. They are also slightly sloped to allow drainage. No soil is used. A rubber mat covers the organic material, providing protection from heavy rainfall. We are using banana leaves, placed on top of the rubber mat, to keep the material from overheating on sunny days.

Illustrated in the photos below is the drainage system (jug in a hole covered with a wooden lid shown above) as well as unprocessed organic matter (fruits and egg shells) compared to material that has been processed by the worms. As worms digest bacteria in the compost, the nutrients trapped in the bacteria are converted to a plant-available form in the resulting worm castings. Both the castings and the liquid in the jug can be used as fertilizer.