Bokashi composting and Effective Microorganisms® – a quick analysis

A few weeks ago an attendee at one of my seminars asked me about bokashi composting.  It’s a term I hadn’t heard before, so I promised to look into it (and the science behind it, of course).  I haven’t had a chance to do much more than a cursory analysis, but even that has proven interesting.

For those of you who, like me, had never heard of bokashi, it’s a composting technique that utilizes Effective Microorganisms® as a way of creating a “positive” compost product using “positive” microorganisms.  Unlike those found in aerated compost tea, these microbes are primarily anaerobic.  They have been packaged and marketed for a number of applications, including water and sewage treatment.  Since this is a gardening blog, I limited my search to journal articles on whole plant experiments.

I found almost 50 articles in my initial sweep through the literature – I pulled out articles that included the word “bokashi.”  (There are many more [over 300] that mention “effective microorganisms” but it will take some time to winnow through those.)  Without reading the abstracts of my collected articles, I separated them into three categories:  top tier journals, lower tier journals, and meeting proceedings.  Top tier journals are generally those that have been around for a long time, have an international distribution, and are considered to be rigorous in their peer review process.  Lower tier journals may include those limited to a university or a single country, written in a language other than English, or relatively new; in many cases, this means that the peer-review may not be as rigorous as for top tier journals.  This may be unfair, but it’s one of the ways that scientists consider the impact of published research.  And finally, published meeting proceedings are almost always unreviewed.

(For those of you interested in how academics stress over journal ranking, you’ll be amused, depressed, and/or in total disbelief after reading this and this in the Chronicle of Higher Education.)

So here’s what I found when I read the abstracts of the articles in all three categories.  Briefly, I noted whether or not the bokashi treatment (which generally included Effective Microorganisms®) was effective in disease control, improving crop yield, etc.  I only read the abstracts, as many of the articles are not available as electronic resources.

Proceedings – no peer review (16)
Bokashi treatment better than whatever it’s compared to: 15
Bokashi treatment no different or worse than whatever it’s compared to: 1

Journal articles – lower tier resources (25)
Bokashi treatment better than whatever it’s compared to: 15
Bokashi treatment no different or worse than whatever it’s compared to: 7
Mixed results: 3

Journal articles – top tier resources (5)
Bokashi treatment no different or worse than whatever it’s compared to: 5

Quotes from abstracts of these last five articles:
“…did not improve yields and soil quality during 4 years of application in this field experiment.”
“We consider EM products to be ineffective.”
“…the chard treated with [EM products] lost considerable water and weight…the organic methods tested produce a vegetable that can not sustain its quality when commercialized through the conventional supply chain.”
“The treatments did not notably modify the physical and chemical quality of the chard when compared with control plants.”
“Overall, the results confirmed the…effect of compost application on plant growth. However, under the conditions of this study, EM showed no special effects in this.”


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Linda Chalker-Scott

Dr. Linda Chalker-Scott has a Ph.D. in Horticulture from Oregon State University and is an ISA certified arborist and an ASCA consulting arborist. She is WSU’s Extension Urban Horticulturist and a Professor in the Department of Horticulture, and holds two affiliate associate professor positions at University of Washington. She conducts research in applied plant and soil sciences, publishing the results in scientific articles and university Extension fact sheets. Linda also is the award-winning author of five books: the horticultural myth-busting The Informed Gardener (2008) and The Informed Gardener Blooms Again (2010) from the University of Washington Press and Sustainable Landscapes and Gardens: Good Science – Practical Application (2009) from GFG Publishing, Inc., and How Plants Work: The Science Behind the Amazing Things Plants Do from Timber Press (2015). Her latest effort is an update of Art Kruckeberg’s Gardening with Native Plants of the Pacific Northwest from UW Press (2019). In 2018 Linda was featured in a video series – The Science of Gardening – produced by The Great Courses. She also is one of the Garden Professors – a group of academic colleagues who educate and entertain through their blog and Facebook pages. Linda’s contribution to gardeners was recognized in 2017 by the Association for Garden Communicators as the first recipient of their Cynthia Westcott Scientific Writing Award. "The Garden Professors" Facebook page - "The Garden Professors" Facebook group - Books:

14 thoughts on “Bokashi composting and Effective Microorganisms® – a quick analysis”

  1. It is unfortunate that you have represented to the public that you’ve done a credit worthy analysis. Good scientific work involves actually doing experiments and confirming results. You made no comparisons of methods employed, protocols followed, crops tested, or even what defined “bokashi”. Had you investigated even a little more, you would have realized it’s not composting. It’s fermenting. I would be more than happy to help educate you about the process if you wish to communicate and become better informed about bokashi methods.

  2. Well, it seems that the author of the above essay ( unidentified as she/he is) has done nothing more than posat a brief review of the abstracts of the available literature. IO don’t believe there was any intention of presenting the commentary as anything more tha what it is…. a commentary designed maybe to pique the readers interest in delving deeper. And DR Green who exactly is your employer regarding research into this product and method?

  3. Bokashi is nice because you can compost anything with it (meat, dairy, etc) that you normally can’t with outdoor composting. And when it’s -40 outside, it’s a little easier to throw the stuff into a bin rather than outside 🙂

    I thought the EMs were to compost the materials themselves without stinking everything to hell. I certainly didn’t read any claims that they were better for soil quality than ordinary compost.

    On the other hand it’s been like five years since I start bokashi, and back then it was extremely obscure (I bought everything mail order), so who knows what stupid claims are being spewed now. If there’s one thing that annoys me to no end, it’s the ridiculous claims spouted by “green” marketing.

  4. Bokashi has always seemed fake to me. It has all the standard red flags.

    * People who recommend it tend to believe in other miracle stuff (compost teas, magnets, homeopathic plant watering)

    * The occassional “scientist” who comes along to back it tends to have a financial interest.

    * There are people on the Internet who swear by it and become angry if you question it.

    * Gimmicky name intended to make it sound foreign and interesting like “Turkish” or “Persian”, but in this case Asian.

    I admittedly got suckered into buying the stuff when I needed a new compost bucket for the kitchen. I was in a store that sold all sorts of organic products and there was a nice looking compost bin with a spout. Marked down with several applications of price tag. I figured at 75% off, I was getting a great deal on a plastic bucket with a spout. I even tried the rice bran innoculated with mystical powers until I ran out. Lo and behold, the bucket continued to compost after I ran out of rice bran. I realize this is highly subjective with absolutely no replicates to back up my claim, but in my experience the buckets decompose stray food scraps without the magic bran flakes.

    Since then, I’ve heard stories from farmers who used copious dollars worth of the bokashi to “accelerate” their anaerobic compost projects. I tried to ask one if they have tried just piling stuff up and timing it and/or tried actually making compost windrows like I’ve seen at professional composting facilities. Needless to say, they became angry when I questioned their purchase of $100/lb rice bran.

  5. well I have been using bokashi for about a year and have very quickly made a nice pile of usable compost for my garden. The bucket smells pickled…not unpleasant at all. I have run out of rice bran before and things do continue to rot. The smell is highly unpleasant and it takes f-o-r-e-v-e-r. It is expensive but a little goes a very long way. I bought 2 lbs in Jan and just ran out at the end of Aug.

  6. I give workshops on composting and I’m interested because some apt dwellers can’t have outdoor compost bins; don’t want indoor worm bins; MIGHT use bokashi, but might not (since I think worm bins are perfectly fine indoors). (But maybe they are squeamish about worms.) So as long as bokashi isn’t worse, it could be an alternative for some people who need an indoor solution. BTW it seems any decomposition process involves a sort of fermentation but I am not a chemist. –Marianne Mueller

  7. If anyone ever did an actual scholarly review of research findings, I would be most interested.

    This certainly isn’t one.

  8. The way that scholarly reviews work is this: first, you look to see if there are scholarly articles to review. Then you look at the abstracts to see if there’s sufficient evidence that *something* is worth reviewing. In this case, the results are inconclusive at best. No researcher is going to spend a lot of time combing through these papers when the conclusion will obviously be “inconclusive results.”

  9. According to these articles, is bokashi the same as any other compost or is it specifically harmful? I’ve spent many hours trying to understand the effect of bokashi on my garden soil. Is it the same as adding any other kind of compost? What could be harmful about it? If I compost mainly kitchen scraps, what is the likely nutrient profile of the resulting compost? Is the leachate harmful? What is it’s composition? I had a soil test done and learned have too much of some nutrients and not enough of others. How do I determine if bokashi will hurt or help?

  10. Abby, it’s not harmful in and of itself – it’s really not different than any other compost. When it (and other composts or fertilizers) are added to soils too rich in nutrients (like phosphate,
    for instance), then you are going to have nutrient toxicity problems. You’ve had a soil test, which is great. Use that to figure out what, if anything, you need to add. Then just find a fertilizer, organic or otherwise, that will meet the need and not add anything unnecessary.

  11. Just for fun, I tested this stuff again with no control or replicates vs. adding a portion of an active compost pile. Neither smelled bad and the active compost “accelerated” the process just as well as the paid microorganisms.

    I also spoke with a farmer in Oregon where composting fresh animal flesh is legal (it is illegal in California). He showed me some pictures of bones in compost piles which is enough evidence for me. Basically, Bokashi does nothing that available microbes floating around everywhere do. It seems the only differences are people in apartments have semi-sterilized material to begin with in a semi-sterile environment (kitchen scraps in a kitchen) and the idea of paying money for something that is normally free appeals to people.

    1. Lacking “active compost”, just what is one supposed to use to innoculate food scraps?

      You’re at least partially right, there’s all kinds of microbes out there that break down organic matter and turn it ultimately into soil. It just turns out that there’s a variety of ways to arrive at the end product. Mis-application of any phase along the way can result in a smelly, noxious mess.

      Bokashi allows you to ferment your food waste in a sealed container. It’s an anaerobic process that kicks off a little bit of CO2 and a vitamin/nutrient/microbe rich leachate that supposedly has a lot of good uses — although I can’t vouch for that as I haven’t attempted to use it for much.

      What I can vouch for is the amazing transformation of food waste that occurs in the bin. If you throw raw kitchen waste into a sealed 5G container and let it sit, (if it doesn’t explode) when you open it, it will smell — really BAD. A proplerly maintained bokashi bucket will smell kind of pickly, fermented, cidery. If you dig around in it a bit you can stir up some unpleasantness, but mostly you can really tell there’s a big difference between pickled food waste and rotting garbage.

      I live in a studio apartment in NYC and have been bokashing ALL of my food waste for the last 2.5 years. Not one scrap of food waste has left my apartment in a trashbag in all of that time. Without bokashi, it really wouldn’t have been possible.

      I was already using a worm bin but was having trouble with the food in the bin attracting flies. Sometimes there would be odors. Also lots of moldy areas that I was always uneasy about. Plus there was the added drag that there were quite a few things that can’t even be added to a worm bin. Bokashi changed all that.

      I throw anything and everything into the bokashi bin. Once it’s pickled, flies don’t seem to have much interest in it and some people add it directly to their wormbin. If you add a little bit at a time, that’s probably fine. I prefer to use a 3-phase process where I let the bokashi go through a bit of an aerobic “heat-up” with soil in a separate container. Managing this container is actually the hardest part — it can produce a lot of odor if you’re not careful. Once the bokashi waste has broken down a bit (i.e. it’s not expelling heat), I’ll add it to the wormbin. The worms dive right in. I just cover it with a little bedding and there’s no flies, no odor, no moldy regions.

      Without the addition of bokashi, I doubt I would have continued with the worm bin.

      Also, you can make your own lacto serum and bokashi flakes. The ingredients are readily available and cheap. All it takes is a little time, attention to detail and patience.

      Have a nice day.

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