Soil Factory Using Bokashi Ferment

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Robert Pavlis

I am seeing the term soil factory used more often, usually in discussions about Bokashi or Vermicomposting. I’ll restrict this blog to discussions about Bokashi, but most of the comments also apply to Vermicomposting.

It is claimed that Bokashi ferment, the material remaining after the fermentation process, can be used to make soil, which can then be used for house plants or in the garden. This would be quite a feat if true. It takes nature millions of years to make soil and now Bokashi enthusiasts can do it in a couple of weeks.

Bokashi Soil Factory, by
Bokashi Soil Factory, by

Soil Factory Using Bokashi

How does the soil factory work? The following description from the Bokashi Composting Guide is a good explanation of the process.

“Making Your Own Potting Soil: To create your own soil factory you will need a large open container or tub. First add a layer of used soil (20 litres), then dump in the contents of your Bokashi bucket and break apart the waste. Next add another 20 litres of soil and mix it into the fermented waste. Finally top off with another 20 litres of soil and ensure that all the contents are moist but not wet. After a few weeks you will have a good supply of an amazing nutrient rich potting soil.” (ref 1)

Plant Science for Gardeners by Robert Pavlis

I wonder how much soil you produce? I’d guess it is just 60 liters, the amount of soil you started with. A pail of Bokashi ferment is mostly water. A small amount of organic matter would be added to the soil but would have almost no effect on the volume of soil.

Soil consists of dead organic matter, sand, silt and clay. A soil factory does not produce any sand, silt or clay so it does not produce soil. The term soil factory is very misleading.

Statements like “A soil factory is a place where you produce high quality nutrient rich soil”, are just plain wrong. It does not produce soil, and there is no evidence that the resulting product is ‘high quality’ or ‘nutrient rich’. The soil structure has not changed. The only thing that has happened is that it has a higher level of organic material, but this organic material has not started to decompose as explained in Bokashi vs Composting.

Benefits of a Soil Factory

The term Soil Factory may be a poor selection, but there are some real benefits to it. I first became aware of the procedure of adding Bokashi ferment to soil through social media; it seems to be a more common practice in Scandinavian countries. In a few weeks the fermented kitchen scraps plus soil are turned into something that looks like soil. You no longer see the pickled scraps.

I gave the method a try and sure enough the fermented material falls apart fairly quickly and seems to dissolve in the soil.

The benefit for the home owner is that they don’t need a garden to get rid of their Bokashi ferment. They can do it right in their home and the resulting soil can then be used for house plants or planting containers. This certainly makes Bokashi more appealing for people living in apartments.

Building Natural Ponds book, by Robert Pavlis

What Does the Soil Factory Produce?

The stories I heard from Finland and Sweden claimed that the Bokashi ferment decomposed in a couple of weeks after being added to soil. I haven’t found a single study that looks at what happens to the ferment once it is added to soil. To our eyes it seems to disintegrate into the soil, but decomposition is a chemical process and we humans can’t see it happening.

We do know that decomposition is a slow process that happens in the presence of both bacteria and fungi. Knowing this, it is almost a certainty that the soil produced by the soil factory does not contain decomposed material. It might look like finished compost, but it’s not.

Traditional bin composting takes months, and even so-called finished compost still takes years to complete the decomposition process.

The result of the soil factory consists of the added soil plus un-decomposed organic matter. There is nothing wrong with that. The real value of organic matter is that it decomposes slowly over time – that is a good thing.

A New Type of Soil Factory

While experimenting with this process I decided to try an improved soil factory method. The current method requires that the soil and Bokashi ferment sit for a couple of weeks. My new method eliminates this two week waiting period, making it much faster.

The Instant Soil Factory

Take your Bokashi ferment and homogenize it in a blender to make a smoothy out of it. Then pour it into the soil. Mix it up and you are done. Instant fortified soil with no waiting period.

The ferment homogenizes very easily in the blender since the food scraps are already mushy and contain a lot of water.

You can also replace the soil with coir and produce a product free of insects and plant diseases. The coir is quite dry and easily absorbs all of the liquid in the ferment. The result is a fairly dry, soil-less mix that has no odor. The ferment will continue to decompose over time and help feed plants.

I call this new method the Instant Soil Factory.


  1. Bokashi Composting Guide;
  2. What is Bin Composting?;


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Robert Pavlis

I have been gardening my whole life and have a science background. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

53 thoughts on “Soil Factory Using Bokashi Ferment”

  1. Hello,

    I am a bokashi newbie and my bucket is a little over half-full. I haven’t figured out what to do with the ferment yet though, and while googling online I stumbled across this helpful page! I have some questions though, and I apologise if you have answered them already – I see the comments to the original post are rather long and I haven’t been able to go through all of them, although I have read the main article about composing myths (in addition to this one). It really helps to hear from somebody who actually has experience in composting.

    I live in the Japanese countryside (in a small apartment – no garden or potted plants, although I have a small concrete balcony) but was born and grew up in a very urbanised city (Hong Kong) and basically I know nothing when it comes to growing things (embarrassing but just to let you know where I’m at…!). When I learned about composting food scraps (several years after I moved to the Japanese countryside), I decided I wanted to give it a try, but was shocked to discover that nobody in my vicinity does this. Maybe I shouldn’t have been shocked as I actually learned about compositing (and bokashi) from YouTube… ironic as “bokashi” originates from Japan!!! – and not from my neighbours or friends. People around here in my town toss out their food scraps in the regular trash to be incinerated and dumped in landfills (this is what I also did, for years, because I didn’t know what else to do). There are no public compost collection bins either, despite this being a rural area with a lot of rice paddies and wheat fields. Most home owners have potted plants and even gardens, but when I ask them about composting food scraps, nobody seemed to know anything about it….

    This morning I called the local city hall to ask if there is a way I could contribute my ferment somehow, but was told that basically if I didn’t have a garden, or friends who would permit me to bury my fermented scraps in their gardens, it was recommended that I throw it into the trash to be incinerated (like plastics and other non-food waste). It was kind of surprising to me that this was the official position of the city hall (in the “recycling and environmental protection” department) in a rural (and agricultural) countryside town… I thought maybe they could introduce me to a local community garden or something, but no mention was made of any such thing despite my efforts to pry any sort of useful information out of the city hall staff…

    Anyway, now you can see why I’m so glad I came across this page!! And I’m now very interested in trying the “instant soil factory” method – ideal for someone like me who lives in a small apartment and doesn’t know anything about growing plants (yet – this may change over time)… The thing is, I’m not sure what kind of container I should buy. I’m interested in trying the method with “coir”, although I need to find out if I can buy that around here (I’m also concerned by a previous commenter who mentioned a foul smell while mixing with soil and coir.) If not, I will buy some soil I guess. So my questions are:

    1. Any recommendation for the type (size, shape, material) of container for the “soil factory”? Should it be bigger than the bokashi bucket or around the same size?
    2. Should the container have a lid or does it need to “breathe” as in traditional composting? Should there be holes in the bottom for drainage or not?
    3. What kind of conditions should the container be kept under… indoors/outdoors? Away from rain? I’d prefer not to attract bugs or worms.
    4. Do I need to keep adding coir/soil to the mix or can I just go on endlessly adding the ferment smoothie?
    5. This relates to Q4, but eventually will I need to dispose of the resulting material as well? It just seems to me that if I am continually adding organic material (the bokashi ferment), then the volume of “stuff” is going to increase over time and my container will eventually overflow? In which case, what do I do with the “stuff”?

    I’d really appreciate your advice… Nobody around here seems to have any answers for me… Thank you so much in advance!!!!!

    • Just use the normal Bokashi bucket and make the ferment. At the end of the process, mix the contents with coir, or soil. Then use the resulting material in pots to grow things, or add it to the garden.

      • Robert, I think JS was asking about a container for the soil factory. If I understood your original post, there’s no container; the smoothie is just poured on the soil surface. It would add a negligible volume to unpacked coir.

        I’ve tried the method. The one drawback I found was that the bokashi smell seemed to be more pungent than in the bin and hung around for a few days. Only a problem if you have the wrong neighbour.

        Personally I still prefer a small area (0.5 sq m) in the garden, rotated as and when I see fit. The smoothie method suffers the same problem as trenching – where to find a plant-free area that needs food? I fork in bokashi to aerate thoroughly, and usually pour bokashi runoff on it too.

        In effect this is an in-soil wormery, a future growing area (gave an incredible potato yield this year) and an instant supply of mulching compost. I use wood offcuts to edge it and chicken wire to stop my local fox from mining for worms.

        The quality of the resulting soil is fantastic. It grows in height a little, but I put this down to the aeration and continuous worm action.

        PS I strain homemade yoghurt to get Greek style. The whey usually finds another food use, but when it doesn’t it too goes on the soil factory. I reason it is closely related to bokashi runoff.

        Forgetfully, I left a jar out one night and next day the liquid was literally full of dead slugs and a few snails! I poured them on the soil factory, and checked hours later for movement; none; dead. Something ate them overnight, probably vermin, so now I always bury them.

        Much cheaper (if you make yogurt anyway) and less distressing than using good beer in a slug trap!

        • The original soil factory is just standard bokashi, mixed with soil or coir after fermentation. So you still have the bokashi bucket you would normally have.

          The New Soil Factory speeds up the process by using a blender to mash up the bokashi ferment – but you still need the bucket to make the ferment first.

        • Hi, thanks for your replies! Yes, I think maybe I was not clear in my original post that I don’t have a garden… Maybe it was a stupid question, I’m just not sure how best to go about the next stage (after the fermentation)… I have a blender so making the smoothie would not be a problem.

          What I’m not sure about is, where to start the soil factory – as I said, I do not have a garden – there is no “ground” nearby where I can bury my ferment. I do have a very small balcony, and I was wondering if it is possible to start a soil factory in some kind of container (planter). I haven’t bought one yet. I don’t have any potted plants yet either. But I have started using my bokashi bucket (just started a week ago). I really don’t want to put it out in the trash as it defeats the whole purpose of trying to reduce waste.

          Does anybody have any tips for starting a “soil factory” in an apartment..? Where to start? This is the basic question I guess… I’m worried about making a stinky mess and/or attracting bugs. So far my ferment does not smell bad. I’ve been using plenty of bokashi bran so that it won’t putrefy… I just don’t know how to go about the next stage, after the kitchen scraps are ready to be “buried”… because I haven’t got a place to bury them….! Not yet, that is.

          • Just like you I only have a balcony.
            I use plastic tubs/containers for the soil factory, 40-60 liters works great.

      • Hi and thank you so much for your reply!! Just to clarify (and sorry if this is a dumb question, but I just want to be certain…) – do you mean that I can just add the coir/soil directly into the bokashi bucket? I’d thought I would need another container for the “factory”…

  2. I get that you think bokashi is a waste of money if you can compost. I wouldn’t be considering it if I had bear-safe backyard compost pile and the patience required to compost over several years in Alaska. But I don’t, I live in a condo and have a worm bin and a community garden plot that’s not easy to access during the long winter. I’m considering adding in bokashi fermenting as a pre-worm processing step, because my partner absolutely refuses to chop scraps up before adding them to the worm bin, and the big pieces aren’t breaking down in the worm bin before their tray’s time is up. I would have two buckets, one in the kitchen that I’m adding to, and one full sealed one stacked on top of the worm bin waiting to be added after the pickling process completes. My goals would be:
    -get breakdown process to happen faster once its in the worm bin, so I’m getting finished worm casings without whole kale stems and avocado peels, etc.
    -avoid smells
    -minimize storage space and labor

    Ideally we’d also be able to loosen the restrictions on what can be diverted from the landfill (onion skins and citrus peels don’t go in worm bin)

    I’m not concerned about the technicalities of “compost” definition, I just want to divert my kitchen scraps from the landfill and into my garden plot, avoid smells in the house, and avoid smells from the garden attracting neighborhood bears.

    Does your experience with bokashi and vermicomposting indicate that adding bokashi to the process would help get me closer to those goals?

  3. Congratulations on the idea of homogenising bokashi ferment. It may be more important than is apparent above.

    Unlike digging in, it is consistent with minimum till methods – a rake should give enough mixing.

    It makes the ferment even less appealing to scavengers, or at least the large ones.

    It must give (much?) greater exposure to air and therefore more rapid oxidation of the lactic acid – which is what makes it accessible to soil life

    It should mean you can amend a larger area of soil from one load of bokashi, and give that area repeated applications. This is going to sustain a larger local soil ecosystem.

    Perhaps most important for the planet, it is easily scalable. In particular, it opens the way for community or even municipal bokashi-to-field systems, for example in urban and peri-urban horticulture.

    May I suggest that you think beyond decomposition? Think what happens next. First the bacteria get it, then the rest of the soil ecosystem piles in to get the bacteria. (Bokashi is from one viewpoint an in-soil wormery!)

    This ecosystem is the only entity that releases plant-accessible nutrients. It also creates some complex carbon molecules (the dreaded “humic substances”) which hang around permanently – and to that extent this IS a soil factory.

  4. The more I think about bokashi the more I wonder if there’s any difference between making it and making sauerkraut or any other lactobacillic ferment?

  5. Robert, I do like your comment about this process not producing soil, but houseplants should not be grown in soil in the first place.

    Most houseplants have very specific needs such as cactus needing a sand based mix with very little organic matter while Aroids need a mix made almost 100% of organic matter.

    So, for the latter I am going to suggest a substrate mix I use that you could add into your Bokashi mix & allow to ferment another week allowing the whole mix to benefit from the process.

    Equal parts:
    Crushed wood based & untreated charcoal crushed to 1/4 inch pieces
    Crushed pine bark chunks or chips at 1/4 inch pieces
    Coconut coir
    Chopped sphagnum moss

    Terrestrial tropicals will benefit from 1 equal part of a premium potting mix.

    This mix can have Bokashi added to it. Add a few red wigglers & this will be a rich substrate for your tropical plants in a few weeks though you can plant in it immediately. You can allow this mix to ferment in your Bokashi bucket or pull it out & add the worms immediately. Up to you.

    Coir will hold its physical properties for up to 20 years in potting substrate, charcoal & vermiculite nearly forever, but the rest will break down within a year or so.

    • Where are you getting this info “Coir will hold its physical properties for up to 20 years in potting substrate”?

  6. I use bokashi and this answered many of my questions and concerns. I still think it is a viable method for those who live in apartments. Maybe that is it’s key advantage? There is a bit more cost involved than in traditional composting, but it’s a lot better than food scraps ending up in landfill.

  7. This article was very interesting to read. I thought the exemple of the blender was quite funny but realised there is a major flaw while reading the comments.

    You mentioned that after bokashi composting the food still looks the same as before which explains why this is not composting. I think it is a valid argument as I think it is just a step in that composting method and it is not composting per se. If that is a valid argument, then what is being put in the “soil factory” or buried in the ground is still regular food. As you mentioned, an apple is still an apple.

    If we acknowledge that a system that just works by leaving soil organisms and time (with good temperature and humidity) to change the food in decomposed material (traditional composting) then we must also acknowledge that putting the pickled food in the soil factory or burying it is also decomposing the matter. Essentially it is the same thing as we leave soil organisms and time do the work (with good temperature and humidity). The only difference is how fast one method is because of the initial conditioning.

    If we reject that those methods are actually decomposing the food, then we must also logically reject that traditional composting is decomposing the food.

    Now in the case of the blender, the physical state of the product is changed using mechanical power which is not the case with either bokashi or traditional composting.

    • If you consider the whole process of fermenting, followed by decomposition, then yes you can call it composting, but most discussion consider the fermenting step as a composting step – which it really is not.

      The blender is a physical process that produces a product that looks just like the Bokashi + 2 weeks in soil process. The reason for using it as a comparison is that most people would easily agree one is just a physical process, but that the other is not. But I believe they are both mostly physical processes and the outcome is fairly similar, on a molecular basis. There is more to this interesting story to come.

  8. Using a blender seems like more work, not less? If the fermented food breaks down in about two weeks anyway, I’d rather just wait, instead of batchblending 2 liters at a time.

    • I was not suggesting that blending is a better option. The point is that just because you can’t see the pieces of food – does not mean it is decomposed. So it does not “breaks down in about two weeks”. Only the visible large pieces become smaller pieces.

  9. Dear Robert
    I like your practical advise. I have been thinking about how you can speed up the process even more. Why not put the compost into the blender and add it straight to the garden. This way the bacteria and funghi in the garden can process the faster. It will be a sort of irganic digestion and it could could be called it „In Plot Composting“

    • Not sure how you are defining compost, but using the normal definition, you don’t need to blend it – just spread it in the garden.

      • Sorry, my English was not precise enough. I am Swiss. So in the (Swiss) German language compost is also the stuff you put on your compost heap.
        So what I actually meant was to put the food left overs into a blender and then directly scatter it onto the soil in the garden. This way you can save two weeks of bokashi fermentation.
        After having read your article about bokashi fermentation I have come to the conclusion that this does probably more harm than good. If I understand correctly, it is important that for Bokashi fermentation no oxygen most be present. So this means anaerobic digestion.
        This is the process used in biogas plants to produce biogas. This process produces rather large amounts of methane and CO2. In a biogas plant the methane is captured and used to produce electricity or it may be even purified and fed into the gas grid.
        However with Bokashi fermentation the methane will be vented into the atmosphere. The International Panel on Climate Change says that Methane is 86 times more potent greenhouse gas carbon dioxide.
        Much lower amounts of methane are produced during normal composting as this is an aerated process. So I think it is very likely that normal composting is much more climate friendly than Bokashi, and Bokashi is even harmful.
        It is probably more environmentally friendly to dispose food leftovers via garbage disposal unit into the sewage system than doing bokashi.
        The sewage treatment plant captures the methane, bokashi cannot do this.

        • Your comment “put the food left overs into a blender and then directly scatter it onto the soil in the garden” is very interesting. In fact, when I did the blending work on bokashi, I came to the same conclusion, and tried just blending kitchen scraps – no composting and no bokashi. It worked just fine, and will be a topic for a future post.

          Your comment about methane is correct. It is very harmful to the environment, and bokashi will produce more than composting. Bokashi is used mostly in very small quantities, at least as described in my posts. The amount of methane produced is small compared to all of the other problems we have with global warming. It also loses less nitrogen compared to compost. Does that offset the methane produced?

          You may be right – putting it in the garbage may be better environmentally.

        • Bokashi produces no methane (or CO2 or heat – it is a mildly endothermic reaction). Assuming you spread the runoff liquid too, 100% of the original carbon, energy and nutrients get to the soil. It does no harm.

          You are confusing anaerobic digestion with bokashi’s anaerobic fermentation. It is a homolactic fermentation (see Wikipedia) which converts some input carbohydrates into lactic acid. Enough is converted to pickle the food waste.

          When the acid is exposed to air it oxidises into something called pyruvate (see Wikipedia) which is, fundamentally, a food energy carrier. That’s why the ferment is consumed so fast. And oxidation is why Robert’s idea of homogenising the ferment is so good: it is both aerated and mixed thinly with surface soil instead of being buried.

          • Can’t you just add lactic acid to food to pickle them rather than buy expensive bran ?

  10. Yes. I have tried this soil factory method for Bokashi ferment. It turns into a soil like structure or more like a ready compost in 2-3 weeks with a nice earthy smell. But I have a problem while mixing this Bokashi ferment with soil and coir. It gives out real foul smell. So this time I have put this ferment and soil in layers and not mixing it to reduce the smell. I will find out in a couple of weeks whether this gives the same result or not.


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