Bokashi compost – composting for small spaces

A traditional composting bin setup can take up a lot of space, especially if you live in the city. But composting in a large bin is not the only way to turn your kitchen waste into nutrient-dense food for plants. In this post, we talk about the Japanese method of bokashi compost or fermenting your food scraps before mixing them with soil directly.

Redirecting resources from the waste stream

We’ve talked about how dumpster diving takes resources that were destined for landfill and reduces it, but we did not talk about how food waste also negatively impacts the waste incineration plant, if your muncipality has one. Waste incineration plants are a whole other issue on their own. But one of the main problems regarding food waste is that food waste is very wet, and takes more energy to burn than it gives back. So by reducing how much wet waste is in your trash, you also increase the incineration efficiency.

Plus, food waste and subsequent compost is so nutritious and great for plants. It would be a shame to just burn it!

Why bokashi?

Regular compost bins are great when you have a larger setup, but they do release some of their nutrients as CO2 and other gases through their air-dependent (aerobic) process.

Bokashi, on the other hand, relies on microorganisms that thrive without oxygen (anaerobic). They keep all their precious nutrients to themselves and provides excellent soil enrichment, both as compost and liquid fertilizer. Similar benefits can be found in worm compost, but without the living, wriggling friends to keep alive, if that is an issue for you.

Bokashi compost setup

In a nutshell, bokashi composting ferments the food waste before they are mixed with soil and decompose to soil. The beauty of this is that the food waste is rendered unpalatable to pests like rats and seagulls, which significantly reduces your risk of having a problem with any local authorities.

Ideally, bokashi is done in a bucket (you’ll need at least two, to rotate) with a tight lid, with a mesh separating the lower part and a tap below that. The fermentation is best done in moist, but not soggy conditions, so with the tap you can remove excess liquid, which, incidentally, is excellent plant fertilizer (dilute 1:10 before use)!

If you don’t have a bokashi bucket and don’t want to buy one, you can also get away with covering the lower third of a bucket with coal or similar. The coal soaks up the liquid and your food waste ferments on top. This gives you no liquid fertilizer, but still plenty of nutritious compost.

Using the bokashi bucket

In addition to the buckets, you also need bokashi bran. The bran contains the good microorganisms that we want to colonize our food scraps.

Now that you’re all set, it’s just a matter of filling your bucket. Simply add food scraps and sprinkle with bran and press it down at the end of the day, or when you have some scraps. Continue layering food waste and bran, and press the content down so you can fill the bucket as much as possible.

Most anything can go in the bucket, including citrus and tea/coffee grounds. I would keep highly processed food out. It can take meat and fish in small doses, but I avoid it, as it takes longer to decompose and can get smelly.

Make sure you replace the lid between each filling and check the tap for excess liquid about once a week. The bacteria we want are anaerobic, so they work best in a closed bucket. When the bucket is closed, you should notice very little smell from it. When open there is a tangy, characteristic smell. We keep our buckets in a corner in the kitchen. They really are neither obtrusive nor smelly.

If your bucket smells like death and decay, something has gone wrong, and the bucket is not colonizing with the right kind of microorganisms.

Maturing your bokashi

When the bucket is as full as you can make it, close the lid tight and swap for the empty one. It is now time for the maturing and final fermentation. Ideally, you would leave your full bucket for at least 4-6 weeks. In our small 2-person household I find this no problem at all, but a larger family might need more buckets to get a good rotation going.

Once your bokashi has finished, you’ll want to mix it with some soil. The quality of the soil doesn’t matter, as the bokashi will turn it all into great compost. You can do this in a large tub in your basement, if you have one, or you can dig it down in a backyard or garden directly.

For a tub, you want soil on the bottom, bokashi and soil mixed together in the middle, and a layer of soil on top. It will smell while you empty the bokashi and mix it all together, but again, with a good “layer” of soil on top, the smell should dissipate and not be a problem when you’re finished.

Now we wait

Unlike traditional compost, we don’t need to wait several months. At optimum temperature, around 20 C (68 F) the bokashi can turn to compost in as little as one month. Below that it will go slower, and below 12 C (53 F) it will be too cold for the microorganisms to get anything done at all. It still doesn’t do any harm, so feel free to leave them like that until spring, but don’t be surprised to find some food leftovers still visible when it starts heating up.

You should wait with planting into the bokashi compost until it has matured. It will be quite acidic (due to the fermentations) when it emerges from the bin, which not all plants are able to tolerate.

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2 thoughts on “Bokashi compost – composting for small spaces

  1. We avoid putting much citrus in our regular compost bin, can you throw citrus in with the bokashi without issue?

    1. Yes, citrus is not a problem for the bokashi. The end result will be acidic anyways and needs that month at 20C (or longer at lower temps) in soil to mature to great compost anyway. 🙂

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