5-Gallon Bucket Vermicompost System

Assembly

The 5-gallon bucket system is assembled by stacking 3-4 buckets together. Each bucket except for the bottom one has holes drilled into the bottom, the sides, and the lid. This allows for the worms to travel from bucket-to-bucket and to aerate the system.

The bottom bucket does not have holes because it is where the leachate is collected. This leachate is the excess moisture that has developed a rich microbial profile and acts as a liquid fertilizer for plants in the garden.

The system has a spigot attached to the bottom bucket so that the leachate can be more easily accessible. The system has 4 buckets which adds a third level of habitat, thus increasing the production space for worm castings in the worm bin.

Set Up

The middle two buckets are filled with bedding. The bedding added to the system was a mix of coffee grounds, food waste, and ripped-up brown paper bags.

Our goal was to have the bedding dampened similar to a wet sponge (not dry, but not dripping wet).

The same amount of bedding was added to every bucket except for the bottom one which collects the leachate.

The worms will come to the upper layer to eat, but will live and defecate in the system’s lower levels.

The bedding and food was given some water a few days before the worms were put into the system. This was done to ensure that the system was wet enough.

Maintenance, Harvesting, and Use

Food scraps are added to the top bucket and are gently mixed in with existing material on a weekly basis.

Worms eat the food scraps and release their castings in the bottom most perforated bucket (2nd from bottom). When this layer is full of worm castings, we remove it from the stack and use castings where needed in the garden. Worms are picked out and returned to upper levels.

We then reposition the empty, perforated bucket to the uppermost level of the system and fill it with a fresh mix of bedding and chopped food scraps. Harvesting occurs every 1-2 months. The leachate collected is used on non-edible plants and trees since it could contain bacteria which could be harmful if consumed.

System Issues

In our first trial, practically all of the worms in the system died within the first few weeks. We suspect that this happened because:

Too many greens were put in when first setting up the system. Without enough browns to compensate for the amount of greens, too much moisture was created which created an unlikable environment for the worms. The bedding did not have enough moisture absorbing, carbonaceous materials such as shredded cardboard and paper, leaves, or straw.

The greens that had originally been used in the bedding mix were not breaking down properly and had created a thick layer of moldy, rotting food waste that was preventing the worms from accessing the new greens being added. Foods that take a long time to break down (avocado pits, etc.) were found, and the greens were not chopped down small enough.

The system did not have enough holes to be well aerated. There weren't any holes in the sides of the buckets or in the lid, greatly limiting the amount of air flow. Without the holes, the greens had to decompose anaerobically. Anaerobic decomposition will take much longer to occur than aerobic decomposition. With this being the case, the worms were unable to survive the length of time it would have taken the greens to anaerobically decompose.

Signs of system issues

Decomposition was not occurring: The level of bedding in the top-most bucket was getting higher after feedings. If the greens that were originally fed to the system were decomposing in a timely manner, then the level should have remained around the same height since new greens were being added as the old ones were breaking down.

Too much moisture: The system got very smelly, which can also be attributed to the lack of air passing through the system. Additionally, the bedding material was clumping up.

Design improvements

The compost maintenance crew drilled holes into the system so that it could be better aerated. The holes added to the sides of the buckets and to the lid were 3/16". Holes were added about 1in below the rim of each bucket and spaced 1in apart. The holes in the lid were 1in apart as well and were done sporadically, making sure to cover most of the area of the lid.

Additionally, about half of the holes at the bottom of the bucket were drilled larger to a 1/4" size. This was done to ensure that the holes were big enough for the worms to travel through. The holes were expanded sporadically and this was done for each of the buckets.

Maintenance Complexity

The system was not very easy to maintain. To check on the state of the compost and the leachate, the buckets needed to be unstacked and re-stacked every time.

The system produced several cups of leachate over the course of several months. We believe this high amount of leachate can be attributed to the system being too wet.

Worm Habitat Restoration Process

We started by adding more holes to the buckets as noted above under the section for Design Improvements.

Next, we removed the remaining greens that were not decomposing properly. These original greens were buried under all the new material that we were adding during our feedings.

We wanted to keep this new, healthy layer of bedding that sat on top, so we scooped it out and set it aside to allow space to scoop out the bad greens.

In the middle two buckets, sawdust, coffee grounds, and ripped pieces from brown paper bags were mixed into the bedding until the moisture levels felt right. Large sticks and wood chips which had gotten mixed in were removed. We also added water to the bedding since we added a lot of brown material.

We used coffee grounds as a nitrogen input in an attempt to prevent the C/N ratio from leaning too heavily on the carbonaceous side. Coffee grounds were also ideal because they helped to absorb the excess moisture.

Once all the buckets seemed habitable, we added a new batch of worms to the top-most middle bucket.

The greens which we removed from the system were placed in a separate bucket rather than being thrown out. We decided to keep them because they could still be used as greens if placed back on top and chopped down more thoroughly.

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