Over the last couple of days I have been harvesting compost from our heap. In theory, you carefully feed your heap with layers of nitrogen and carbon rich ingredients, build a sufficient volume to encourage a high core temperature and then wait for a while to produce a gorgeous, rich, dark compost. In practice, we tend to throw things on as they become available, don’t have enough to get a really hot heap and need to get compost out while we are still adding new stuff so I have had to come up with a different approach.
The first element of my strategy is to maintain two piles next to each other. On one side I add new material; on the other, I leave well alone. When the untouched side starts to look like a pile of earth and the weather is relatively dry, it is time to harvest. I take spades of this rich earth and use a riddle (a heavy duty garden sieve) to separate into relatively fine compost and larger lumps. Some of the larger lumps can be squeezed by hand to break them down and pass them through a second shaking of the riddle. I then empty the remaining lumps and repeat.
Compost and lumps are collected in a couple of separate tub trugs. The good stuff then gets transferred to an old plastic bin, from which I can take compost when I need it. The lumpy stuff is effective as a mulch round established plants, allowing air and water to pass through to the soil below and gradually breaking down and releasing its goodness.
To finish the process, I then turn the old input pile over onto the now empty space (which mixes it around and lets plenty of air in) where it can sit and mellow while a new input pile is started. The process is quite labour intensive but gives a relatively quick route to good compost outputs using the materials and space available.