What studies / evidence is there that Bokashi tea actually has extra nutritions for plants?

Question

So I've recently started bokashi bucket composting and I'm really enjoying it as it's an easy way to compost indoors.

The bokashi bucket also provides bokashi tea every couple of days and lots of places on the Internet and also even in the instruction manual of the bokashi bucket says that this liquid contains lots of good stuff for your plants provided it is diluted adequately as it's quite acidic.

However, I've just read an article (http://www.gardenmyths.com/bokashi-composting-myths/) where it's stated that bokashi tea doesn't have any nutrients at all.

It contains 0.05% calcium, 0.14% potassium and 0.01% magnesium, indicating low levels of nutrients. After diluting it by 100 it is essentially water.

I thought this was an interesting claim. So I'm just wondering, is there actually any evidence that bokashi tea is any better than water or is it just conventional wisdom that just seems to make sense but hasn't actually been proven? Has anyone used bokashi tea and found it works? I just ask because the tea apparently has other uses as well so if it's not good for the garden, I might as well use it for other purposes.

Answer 1

The only evidence that counts is scientific trial evidence, preferably including an NPK and trace elements readout, and there is none on bokashi tea. People may perceive that it's good for their plants, houseplants or otherwise, but that doesn't mean it actually is doing anything for the plants - the fluid in it might be more useful to the plant than any nutrients it may or may not contain.

Scientifically, as the article you linked to says, the jury's out - the arguments put in that link are entirely logical, particularly from the point of view of the micro organisms involved. Aneorobic organisms do die in aerobic conditions, so as soon as the bokashi compost bin contents are transferred outdoors, either into ordinary soil, or added to a compost heap which is turned regularly, they will die. Given this is not made clear by advocates or sellers of the bokashi system, in fact its claimed the microorganisms are beneficial in a compost heap, it certainly makes me wonder whether the other claims made for the tea are genuine.

One thing though - the bokashi tea is not going to do any harm, so you if you've got it, you might as well water your plants with it. And recycling kitchen scraps in this way is still a useful thing to do because it avoids landfill, as well as the convenience if you're in an apartment or on the upper floors and any compost heap or soil to bury the bokashi in outdoors is a good distance away. Once the bokashi compost is transferred either to a compost heap, or buried in the ground, normal composting/rotting processes will take over, as the acidity reduces.

Answer 2

Some articles seems to show that there are evidence that bokashi tea is better than water:

• Long-term effective microorganisms application promote growth and increase yield sand nutrition of wheat in China
• Is there an effect of ‘effective microorganisms’on EM-Bokashi in banana (Musa ssp.) production?
• Response of Application of Imperata Bokashi on the Growth and Yield of Radish on Alluvial Soil (only the abstract is in english)
• The use of bokashi as a soil fertility amendment in organic spinach cultivation (this one measures traditional compost, vermicompost and bokashi tea, and states that bokashi tea has more nutrient and better performance).

I'm not an expert, but from reading this, it seems to me there is benefical effects of bokashi (be it tea or compost), but maybe I'm biased because I find it fun and I misread those studies.

Answer 3

I came across Evaluation of bokashi fermentation leachate as a biofertilizer in urban horticulture which attempts to answer the following question :

can bokashi leachate be used as a fertilizer and what needs to be considered when applying this method?

Bokashi leachate is what the rest of us calls "bokashi tea".

It's an interesting read (and it's only 25 pages). In short, the conclusion is that bokashi leachate, regardless of what you put into your bokashi bin, is low in nitrogen but contains sufficient amounts of phosphorous, potassium, magnesium and sulphur (compared to a commerical reference fertilizer). It's also noted that the leachate must be complemented with other fertilizers in order to supply your plants with all essential minerals.

It is obvious from the results of this experiment that the proportions of plant
mineral nutrients in bokashi fermentation leachate irrespective of food waste source, need to be adjusted in order to obtain a functional fertilizer. Combination with fertilizer rich in nitrogen and calcium is especially important, as the bokashi leachates were very low in those elements

Bokashi tea from household scraps produced bokashi tea with the greatest amount of nitrogen.

So, to answer your question, the bokashi tea apparently contains nutrients benificial to your plants (such as phosphorous, potassium, magnesium and sulphur), but you can not use it as the sole fertilizer. You need to combine it with at least some other source of nitrogen and calcium.