I thought that compost heaps might be a fun addition to the gardening skills. They could be a good way to dispose of things like paper cups (biodegradable!), pumpkins when the season is over etc. To build the compost heap you would need to collect some timber, place some dirt in to prime it, and feed it an appropriate mix of materials.
As a result you would then be able to gather a compost material that acts like guano.
Any thoughts?