Harvesting Black Gold from a Compost Bin

Once you have set up a vermicomposting bin with sufficient bedding and food scraps, the worms will start doing their job and spew nutrient-rich castings. In fact, a handful of red worms can easily work their way through a decent sized bin within 2 to 3 months itself.

However, vermicomposting is a cyclical process where you keep adding more greens and browns while removing the castings from time to time to use them as compost.

This brings us to the question – how do we reap the rewards, i.e., to say how do we separate the compost from the worms and remaining pile? While it would be tempting to just dump the entire contents of the compost bin in the garden, the worms will not survive there and you will also need to set up a new bin with fresh worms again!

Following are a few methods of how to harvest the castings from a compost bin while keeping the remaining contents functional:

• What many people do is just tip the compost bin onto a plastic sheet before getting down to the messy task of separating the castings by hand. The crumbly dark brown material is collected on one side leaving the worms, eggs and undigested scraps on the other. These can be safely transferred back into the bin to continue with the chomping and excreting process.
• Alternatively, you can work outside under the sun and make cone piles of the bin contents. The worms will burrow to the bottom to get away from the light and only compost is left at the top.
• Some people just prefer to shine a bright torch into the bin. The worms again shy away from the light and burrow into the lower layers of the compost pile. The top layer of compost is safely removed before repeating the light process on subsequent layers.
• A simpler technique would be to push the entire contents of the bin to one side. Keep adding fresh scraps and bedding only on the other side and watch the worms automatically migrate to the ‘food’ side leaving nothing but rich decomposed material on the other end. This can take a month or so. Scoop out the finished compost before leveling the bin with more food once again.
• The tray system of compost bin emerges as the easiest when it comes to ‘collecting’ droppings for compost. All you have to do is add a new tray of greens and browns at the top. Every tray has holes at the bottom and the worms will follow the food by climbing up to the new tray, leaving nothing but black gold in their wake. Just remove the bottom tray once all the worms have shifted (about 4 weeks) and use as you please!

It’s always better to check the finished compost again for any signs of remaining worms or even their eggs. Sort them out carefully before returning them to the compost bin again.

The author is a passionate fisherman and writes extensively on compost bin, fishing worms related topics for fishing.