Urban Composting using Red Worms
Composting is the Alpha and the Omega of food. Compost replenishes the nutrients lost from the soil during food production, at the same time it deals with the bucketloads of organic kitchen waste that accumulates during food preparation. The compost beautifully connects the garden with the kitchen, and vice versa.
No farm? No garden? No Problem!
What about those of us who don't farm? Those who don't even have small yard? Not that uncommon in cities, even though people still tend to have a kitchen there. For all those who think that this situation makes composting unfeasible, I'd like to share my experience in urban composting using Eisenia foetida, or California Red Worms, first in a Budapest apartment without even a balcony, then on my rooftop in Mexico City.
We are all producers anyway, so let's make the most of it.
Before getting immersed in the details of urban vermiculture, let's stop and think about all the stuff we add to this world on a regular basis: many household garbage bags contain all kinds of lovely-nasty things, from eggshells to tea-bags, from banana peels to coffee grounds, from toenail clippings to that cucumber that grew moldy from being ignored for too long. Not very nice gifts to the world, at least from our perspective. So it's not surprising that they are generally seen as a 'problem'. Also, our trash can would be so much cleaner without all this smelly and gooey organic garbage.
Now let's imagine getting a regular supply of liquid fertilizer (maybe 4 liters / 1 gallon every week), as well as solid humus (around 40 liters / 10 gallons every 6 months). That is a lot, especially for someone who doesn't have a garden! But in their converted forms these former problem items become highly desired goods by those who do, so they can be sold, traded, or gifted. In the end, the little effort put into it pays of quite handsomely.
How does vermicomposting work?
The principle is pretty straight forward: Decomposers, such as fungi, bacteria, and other microorganisms break down our kitchen wastes and make their nutrients available for plants. There are thousands, even millions of these useful little critters, so how can we collect them all to form an ecosystem in our little bin? Fortunately, there is something like a packaged deal:
Many microbes that are happy to eat our food scraps live in a close symbiosis with another important decomposer, the composting worm (aka California Red Wiggler or Eisenia foetida) and they can be found in the same dirt the worms live in. Together they can turn our kitchen waste into nutritious humus, given the proper conditions. It’s important to mention, that it’s not the worms who bite into the apple-core, but all the microbes digest it down to a juice they all slurp and exude. Yum! This is also the reason why it’s always best to get the worms with a good amount of soil as inoculant.
For the bin I usually use a 40 liter / 10 gallon storage box, ideally the stackable kind, which will come in handy once the first bin is full. Drilling lots of small holes on the bottom will make sure that it drains well, and prevent the foul smell that accompanies anaerobic decomposition. The drained liquid, by the way, is the fertilizer mentioned above, sometimes referred to as 'compost juice' or 'worm tea'. I use the lid of the box as a saucer to catch it. From there I let the compost juice drain through a strategically placed hole into a bucket. It’s important to make sure the entire system is sufficiently inclined, so the water can drain in its proper direction.
Making it nice and comfy inside
Once their home is completed it needs to be furnished before our decomposing friends can move in. Fill the bin half way with some organic material, preferably high in carbon, such as dry leaves, straw, hay, woodchips, or if these things are hard to find, ripped-up pieces of cardboard, and paper. Ideally I’d use a good mix of whatever I can find. I usually also include a handful of forest soil, in order to inoculate the system with wild microbes, as well as a good number of thin sticks and twigs, to guarantee aeration when the compost starts to compact. To really make the new tenants happy, it’s also a good idea to prepare some partially composted food, as it is the juice seeping out of the decomposing food the worms live on.
The needs of this community of decomposers, as anyone who has composted before will know, are a good ratio of carbon and nitrogen, good aeration, and sufficient moisture. As for the worms, they are also not too fond of light, so it’s good to keep the inside of the wormery in constant darkness. The bin should be set up in a shady spot, and protected from the rain. Worms need moisture, but they can’t swim! When temperatures approach freezing they will curl up and go dormant, only to become active again in the spring. So don’t assume they froze to death, they’re just sleeping.
Once the bin is ready the worms can arrive. The old adage ‘the more the merrier’ certainly applies to them, as long as they are of the right kind of worms. Using regular earthworms, or night-crawlers, will most likely kill them, dooming the entire composting system to fail. For my first worm-bin I was given a kilo of red worms by a friend. In my latest one, however, I had to make do with only about 200 individual wigglers, which I bought for an arm and a leg from a stingy worm farmer. They immediately disappeared into the box, making me wonder if they were still alive for the next couple of months. But these Red Wigglers are amazing at multiplying: if they are happy, they can double their population in only 90 days.
Running the system is super easy, and once the routine has become established, it will almost run itself. Every time I produce organic kitchen waste, I place it into a small (1 liter / quart) bin that I keep next to the kitchen sink. This one I empty every 1-2 days, right into the worm box, on top of everything that’s already in it. Next, I use some carbon-rich material to cover it with. Since most of our food is high in nitrogen, this step is essential. Once again, I could use leaves or straw, but in an urban setting newspaper is a lot easier to come by, or bank statements, or other printed propaganda. It is important to make sure this cover material does not include any harmful substances for our microorganisms, such as lead-based ink or bleached paper. My experience in Hungary and Mexico has taught me that most newspapers can be trusted, even the colorful ones. What I still avoid, though, are glossy prints that are almost certain to include plastic.
Covering the food will not only add the necessary carbon, but will also control the smell and keep invading insects in check. To maximize efficiency I like to rip the newspaper in stripes, and once it has completely covered the little pile of food, I pour some water over it. The water makes the strips stick together, hiding the food underneath, ready to be discovered and colonized from below. Before watering it, I usually empty out the effluent bucket, so it won’t overflow. This worm-tea I collect in a bottle to use to water my plants, in a diluted form. Finally, to protect the worms from the light, and to reduce evaporation, I place a cardboard lid on top of the bin. An old piece of carpet, blanket, sweater, etc. can also do the trick, while keeping moisture from evaporating. Just make sure there are no poisons involved.
As for the dos and don’ts of feeding the worms, the rule of thumb is: they’re not too picky, but are generally vegetarians. Also they are not too fond of oily stuff, and they absolutely hate salt! So I mostly give them fruit and veggie pieces that accumulate while preparing any meal. They don’t object to cooked food per se (cooled down, of course), but since that usually includes oil and salt, it should probably be avoided. Otherwise they get everything from flowers to salad rests, even the dust from the floor. Quite obviously, though it can’t be stressed enough, harmful chemicals should be always avoided!
Even the water I use on the worm bin I set out in the sun for a while to let the chlorine evaporate. Also, the smaller the chunks I give them, the faster the decomposition will go. Putting their daily food into a blender and pouring it on in liquid form would make it even more readily accessible, though I’ve never gone that far in my efforts.
At this point many users may wonder about possible insects this indoor worm farm could attract. Sure, the better you cover the food, the less insects you have, but in my experience it was hard to avoid a small population of flies. Though they tended to be the tiny fruit flies, and not the pesky houseflies, it can still be annoying to have them around. Fortunately, their population came suddenly under control, just when it seemed like it was getting out of hand…
The solution was a natural predator, who just showed up on its own, in form of a little lizard. I have no idea where it came from, but it quickly made itself home on my kitchen curtain, from where it hunted the flies with agile determination. First I celebrated this incident as a unique marvel of nature, but since then I have seen many lizards hanging around my worm-bin I keep on the roof here in Mexico. They seem to find delicious flies, even though I don’t! Just goes to show how effective they are.
Completing the cycle with a second bin
Once there is no more room in the bin to accommodate more compost it's time for a second bin. After drilling its holes similarly to the first one, I just place it on top of the first one, letting it slide down all the way to the top of the compost. I even push it down a bit, to make sure it is in complete contact, so the worms can crawl through the holes into the second bin. This takes time, of course, but there is no rush.
With a similar substrate, and regularly added fresh food, the worms will want to migrate upwards, especially once they have eaten up everything in the bottom bin. The rest of the compost will be taken care of by other microbes, so by the time the second bin is full too, the first one will be ready to be emptied and placed on top. This whole cycle takes about a year, depending on how much you produce.
Okay, so we’ve kept our kitchen trash food-free for a year, the plants in our home have grown like crazy since we started feeding them with the worm-tea, and our house lizard is getting chubby while keeping the flies to a minimum. So one day we reach the point when the second bin is also almost overflowing with compost. What now?
Instead of getting a third bin (and a step-ladder that would eventually be needed), it’s time to empty the first bin, and set it on the top of the second. This should give the user a sack full of good humus. Now I’ve seen people plant straight into that, and in fact, lots of time you’ll find volunteer plants growing out of it. But this fresh vermi-humus has so much potential that it would be a waste not to dilute it.
The first time I harvested a batch of 50 liters, it ended up revitalizing 500 liters (that’s more than 130 gallons, or about half a ton) of exploited, nutrient-poor soil in a nearby community garden. And yes, there will be some worms left in this humus, which is exactly what we want. After all, the organic decomposition doesn’t stop just because it was taken out of the bin. And why should it? Especially if we mix it with used soil (once again without any chemical poisons), still more organic matter, and start growing plants in it, the continuous cycle of nutrients will go on and on. The most exciting part is starting just now, and to think back that it all came out of our kitchen makes the whole endeavor worth while.
