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.”
Interesting.