Bokashi Composting

I recently spent some time at Mahadevi Ashram in Tzununá, Guatemala. One of the beautiful karma yogis was working on this incredible compost project, and I was so fascinated that I asked her to teach me a bit about it so I could share with you all. She ended up writing a whole article to share with us! For many of us in temperate zones, we’re entering into a season of planting, so we are eager to make our soils rich with nutrients and alive with microorganisms

Thanks so much to Jocelyn Ames from Mahadevi Ashram for this incredible contribution.

What is Bokashi composting and why do it?

Bokashi composting is an anaerobic composting technique. Essentially it’s a process of fermenting organic materials in an environment which is devoid of oxygen. Unlike with more commonly known aerobic composting methods, anaerobic composting doesn’t leave you with a pile of dirt that looks almost like soil. It doesn’t break down the material as far but it leaves you with a more richly bioavailable nutrient source that looks like a slightly mushier and more digested version of what you put in. In the next stage of decomposition (in the soil or in an animal’s digestive system) this material will break down much faster and more completely than if it hadn’t been ‘pre-digested’.

Bokashi compost (organic material with inoculated ‘bran’ material)

How does fermentation work in Bokashi compost?

Fermentation in general is a process which digests organic material and sort of ‘opens it up’ so that whatever you feed it to afterwards (the soil, animals or people) can absorb much more of the available nutrients.

A great advantage of Bokashi composting is that you can compost all of your kitchen scraps, even dairy, bones, meat and cooked foods which typically are not recommended in a normal aerobic composting pile because they attract pests and/or go rancid. You can even compost animal manure (including dog poop) with this method! Bokashi composting is done in a sealed container so pests can’t get in and it can be done without any smell. In fact, the final product has a sweet/sour smell, not the foul, putrid, sulphurous odours that we might usually associate with anaerobic environments. This is due to the fact that Bokashi composting uses limited and specific strains of naturally occurring soil microorganisms to do the digesting work. These are yeasts, lactobacillus and purple non-sulphur bacteria which are the same as/similar to those found in yoghurt cultures. In fact, when I brewed up these microorganisms I made delicious creamy yoghurt as a “by product”! Bokashi composting is also a very fast process. Once you have it all set up it only takes 10-14 days for your kitchen and garden scraps to be pickled to a mush!

So how do you do it?

To set up an anaerobic Bokashi composting system:

The Short Version

You need
    •    a sealable bin, into which you layer
    •    inoculated Bokashi ‘bran’ with your organic materials (kitchen scraps, animal fodder etc.). The bran is made up of a carbon-rich substrate (host material) like leaves, woodchip, sawdust, newspaper, corn husks or wheat mill run. The inoculant is a concoction of the strains of beneficial anaerobic microorganisms mentioned above. To this you add…
    •    a mineral-rich sugar like molasses or panela as an energy source for the microorganisms.

It seems you can quite easily buy inoculated Bokashi bran and even specially designed Bokashi bins online. However, I’m in Guatemala so that’s not really an option and besides, it costs quite a bit of money and I like doing things like this from scratch by myself. So I researched how to make the inoculant which took just over two weeks to brew up in two separate parts:

DIY: Making Inoculated Bokashi “Bran”

I made a lactobacillus serum (LS) and a brew of Beneficial Indigenous Microorganisms (BIM). There are specific instructions online (I mostly followed the instructions on this website: The Unconventional Farmer) but essentially the process of making the inoculant involves attracting and collecting the desirable microbes, leaving them to ferment and then feeding them sugars as an energy source to allow them to rapidly reproduce.

Here’s a more drawn out explanation of what I did:

For both the LS (lactobacillus serum) and BIM (Beneficial Indigenous Microorganisms), the first step was to collect the naturally occurring microorganisms from the air and soil respectively. In both cases the carbohydrates attracted lots of bacterias and moulds.

Making Lactobacillus Serum (LS)

I left a jug of oat-rinse water standing out in the kitchen for 5 days with a few raisins and a cabbage leaf inside it (these foods have a lot of lactobacillus on their surfaces – you know the shiny layer that you can rub off and then reappears?).

To brew up and isolate the useful bacterias for the LS I added milk (lactose) to the oat-rinse water. This fed the lactic acid bacterias which had made their way to the oat-rinse water (from the air) so that they outcompeted the bacterias I didn’t need. After a few days the brew separated into a yellowish serum of whey and lactobacillus and a by-product of creamy curds (delicious yoghurt!). I strained the curds out of the whey/lactobacillus and we ate them for breakfast and the serum was fed a whole load of panela (you could use molasses) as an energy supply to keep the lactobacillus happy while I was finishing off making the BIM (which takes a little longer).

cooked rice was loosely buried in the soil for several days

cooked rice was loosely buried in the soil for several days

mouldy rice + equal weight in panela (sugar!)

mouldy rice + equal weight in panela (sugar!)


Making Beneficial Indigenous Microorganisms (BIM)

For the BIM I loosely buried a number of wooden boxes with cooked rice in them into different parts of the ashram property for 3 days. I buried them in different microclimates and soil types to get a wider diversity of microorganisms.

After 3 days in the soil, the rice for making BIM was taken out of the boxes. By this time the rice had attracted lots of white mould and bacterias which were indigenous to the local soils. I brewed up more of these microbes by adding a whole load of panela to the mouldy rice and leaving it for a few days to ferment and become liquid. Then I added water and let that sit and ferment more for another 5 days or so.

Finishing the Inoculant!

At this point I strained out all the liquid from the BIM and added it to the lactobacillus serum. The inoculant was ready for use! A good tip to mention at this point is that for the whole of this process the biggest indicator of whether you’ve done it right and whether the brews are ready is to use your nose! Fermenting with these bacterias should give off a sweet/sour smell, not the expected rancid smell of naturally-occurring anaerobic decomposition.

Next I inoculated a bucket-full of woodchip (bran) with this solution and yet more panela (man these guys have a sweet tooth!) and a bit of water and – ta da! – I had my inoculated Bokashi bran! I bought a big plastic barrel with an airtight lid and now I just layer our cooked food scraps into the barrel at a 50:50 volume with Bokashi bran until the barrel is full. I try to deposit food scraps into it only a couple of times a week to keep the environment as oxygen-free as possible. It takes just 10 days for a deposit of food scraps to ferment down into what is called a pre-compost so 10 days after the barrel is full I’ll end up with a nice load of ‘pre-compost’ which is a sweet/sour smelling, quite acidic mush which is full of beneficial anaerobic bacterias and enzymes ready to be absorbed by the soil and plant life in the ashram gardens. I could also choose to leave it all in the barrel for 6-12 months. Doing this will kill any dangerous microrganisms due to the acidic environment. In an aerobic compost the heat will do this but anaerobic composting doesn’t get as hot and the elimination of pathogens occurs more slowly and as a result of the acidity instead.

Using the Compost

Tzununa, Guatemala

Tzununa, Guatemala

Directly in the garden

An important note on using this Bokashi precompost in the garden: If you’re applying it directly into the soil dig it in to a depth of 2 inches. Also, because it’s so acidic it’s important to leave it for at least 10 days before planting in to it. (Plant roots will burn in it until it has had time to come to a more neutral pH by being digested further aerobically.)

Add to your aerobic compost

Alternatively, you can also add this pre-compost into your aerobic compost pile for at least 1 month. When you do this the anaerobic bacterias and their waste products become a great food source for the aerobic bacterias in the pile. You’ll also be diversifying the microbial life in your compost which is always a good thing. (Bacterias digest sugars and nutrients in the soil, converting them into plant-available forms. Different strains of bacterias can digest different sugars and nutriens from your garden’s soil so the more different types of bacteria there are, the wider the range of bio-available sugars and nutrients that are available for you plants! Just like the role of sauerkraut in your belly.)

Compost tea

You can also make a compost tea out of the pre-compost and even feed it to a vermicompost system (surprisingly the worms don’t seem to mind the acidity). Also, as the Bokashi compost ferments in the barrel it produces a liquidy leachate which you have to strain off. You could also poke holes in the bottom of the barrel and catch it in a bucket (this won’t affect the anaerobic environment in the barrel too much). This leachate is great for pouring into drains, pipes and septic systems to get rid of slime.

makin’ compost tea! just needs to be strained

So that’s pretty much it! A super awesome fast way to compost pretty much anything organic!

Thank you, Jocelyn, for your enthusiasm and expertise! We hope that everyone can benefit from this information about Bokashi composting and use it to your benefit as we move into spring.

Diana & Team ASY