The first thing I (obviously) had to do was dig the actual trench – certainly the most labour-intensive and tedious part of the job. The depth and width of the trench is definitely up to you. I chose not to go down quite as far with this trench as I did with the one in front of the tomato bed. Keep in mind, the deeper you make it the more anaerobic it will be down below. This may or may not be an issue – just something to consider. Deeper (and wider) trenches have the advantage of being able to hold more material.
Next, I added a lot of coarsely shredded corrugated cardboard. This creates a bit of a ‘false bottom’, helping to absorb excess moisture from the rotting waste materials, as helping to balance the C:N ratio of the mix (I like to err on the side of higher C when vermicomposting).
It may look like straw, but this is actually partially decomposed material from my backyard composters. As you may recall, I had zero luck when I initially tried using my backyard composter (only one was active at the time) to compost food waste, but once I had a lot of straw available I was able to start using the composters again – with much greater success, I might add.
This pre-composted material should create a good ‘habitat’ for the composting worms added later. You don’t really need to add this (I didn’t add any to my first trench) – I just happened to have it on-hand, and knew it would work well in the trench. This is important to keep in mind when building a composting trench – don’t focus so much on exact instructions as you do on the principles involved, and the materials you happen to have on-hand. If I installed 5 trenches, I can pretty well guarantee that they would all be different – BUT, they would all be constructed with the principles of vermicomposting in mind.
Here is another layer of shredded cardboard. This time it was shredded egg flats (from the restaurant) – in my opinion, the best kind of cardboard to use for vermicomposting. As you can probably tell, the vermicomposting trench is set up in a ‘lasagna composting’ manner, with alternating layers of ‘greens’ and ‘browns’ (again, with more emphasis on browns, since it is a worm system).
Next, I added a lot of chopped up food waste – apple peels and cores, carrot peels, turnip peels, lettuce, broccoli stalks, egg shells etc. It was added in fairly shallow layers, but given the length of the trench, it was actually quite a lot of material.
