Bokashi Expert’s Guide Part 2 of 3 – Fermenting Food Waste, Apartment and Condo Use, Commercial Applications, and more.

How fast and efficient is Bokashi fermenting compared to composting or burial of food waste?  It is 10 times faster than composting and yields a far richer end product for your plants and garden.  In Part1we talked a little about the differences in fermenting versus composting and went over some of the obvious advantages.  You don’t need to turn a pile, turn a bin, water the pile, worry about the carbon to nitrogen ratio, deal with insects or rodents, put up with piles of decomposing vegetable matter, or wait for months to get your product for the garden.

With bokashi fermenting as was explained in part 1, it is a two step process that takes about 7 to 10 days for the fermented material in the soil to be completely digested by the soil microbes. You can process all kinds of organic matter when you bokashi ferment wasted materials including dairy products, egg shells, bones and meat that should not be used in composting.  Animals will not be attracted to or dig up properly fermented organic matter.

Bokashi fermenting is an acidic anaerobic fermenting process.  You now know after reading Part 1 that fermenting in this case is done in a closed container that excludes all oxygen (the fermenter).  You should be aware that the design of the fermenter is very important because the reaction will not proceed properly if even a small amount of oxygen is allowed to enter the system while it is fermenting.  After the fermenter is filled, it must be set aside completely sealed for at least 7 days with oxygen excluded to complete its process.

Sometimes the question comes up about methane production.  People hear that fermenting produces methane.  When you bokashi ferment, the system rapidly acidifies because of the microbes that are used in this process.  Methane can only be produced at a neutral pH (non-acidic condition) and will never occur in a properly run bokashi fermentation.

I would like to show you the quantitative measurements demonstrating how efficient this process of bokashi fermenting can be when done simply and properly.  It is truly impressive how wonderfully active all the microbes are working together to create a great product for your soil.  They are solving your garbage problem, saving you money, and giving back a soil that feeds your plants beautifully.


Why not just bury food waste?

Anyone who has ever done this and taken the time to dig back into that soil will tell you it just doesn’t go anywhere very fast.  If you bury food waste it smells, attracts flies and rodents, and sits in the soil even under ground for a long time.  In a controlled experiment, 1 cubic foot of food waste was buried a foot under ground and allowed to remain in the ground 8 weeks.

8 week buried Foodwaste

The waste was then recovered by filtering the soil through a ½ inch screen wire sieve separating soil from the food waste remaining at 8 weeks in the soil.  The rotting tomatoes, bones, vegetable matter are virtually intact.  There was a strong putrid smell in the area where the waste was buried and flies were abundant at the surface of the soil even though the material was buried well below the surface.  Ninety percent (90%) of the waste was recoverable at 8 weeks after it had been buried.  Obviously the soil microbes were not able to readily attack or degrade this waste material as presented to the soil.

Buried food waste after 8 weeks in the soil without fermenting

If you just bury food waste in the ground it won’t break down adequately and you will have a stinky mess on your hands.


Bokashi Fermenting Food Waste Pre-Processes the Waste for the Microbes

When you bokashi ferment the food waste it is like preparing a banquet for the soil microbes.  The first step using the fermenter results in a metabolically converted material that the soil microbes can rapidly attack.  This is very different from just burying the food waste material in the soil.  Here are some quantitative measurements showing by contrast how fast the material will be broken down when treated properly.

You can do this in the ground directly or in a planter box.  Here we show the apartment or condominium dweller that even if you only have a small balcony or roof top space, you can beautifully process your food waste in a container and feed your plants.  To do this you will want a couple of containers so that one is used to prepare rich soil that is then used to feed your other plant containers and plants with good soil.

When you ferment food waste it is best to use 2 fermenters.  One fermenter is being filled and processing food waste generated each day while the second one remains sealed so that oxygen is always excluded.  When the first fermenter is filled, it is set aside while the second one is then filled.  When the second is nearly full, the first one goes to the garden so its contents can be buried.  The empty one then is ready to fill when the second container is full and in this way a continuous cycle is established moving fermented food waste to your garden.

Every couple of days a liquid “tea” is removed from the fermenter and discarded down the drain or diluted 100:1 with water to be used as a fertilizer on house plants or the vegetable garden.

It should be observed that the fermenter contents are given a sufficiently long period to complete the fermentation process (while the other fermenter is being filled) before the contents are taken to the garden for burial.  Experience has shown that a period of about 7 to 10 days is all that is needed to complete the fermentation process.  But there is no hurry to get things buried.

In this example we took a 25 gallon plant container and filled it with ordinary soil.  We then fermented food waste filling our fermenter over time.  It took about 8 weeks to get a 5 gallon fermenter filled which I find is typical for two people using the standard fermentation system.  You can estimate this is equivalent to 200 pounds of food waste fermented over 8 weeks time.  That 200 pounds of food waste fermented took 8 weeks to collect and will sit for an additional 8 weeks sealed while the second fermenter is being processed.

The liquid removed during the fermentation process is very rich in microbes, nutrients for your plants, and enzymes that were involved in breaking down cells in the food waste.  It is mildly acidic.  Usually this liquid will have a pH of 4.5 to 5.0.  When it is diluted 100:1 with water it is perfectly safe to apply to your soil and plants and it will not make your soil acidic because the soil microbes will digest the fatty acids that account for its acidity.

In this example screened soil was placed in the plant container.  The 5 gallon fermented contents (processed food waste) was then mixed with the soil in the plant container and then covered with additional soil and left alone for 2 weeks.  The soil from the plant container was then removed and run through a screen to collect any residual food waste that had not been processed by the microbes to see how rapidly waste that had been pre-processed with fermentation could be broken down by soil microbes.  This was soil identical to the soil used to bury food waste that did not disappear even at 8 weeks.

Fermented Food Waste buried in a 25 gallon plant container

As you can see in the images shown, the container is sufficiently large to hold all of the fermented waste material in a 5 gallon fermenter with plenty of room for soil to mix and bury it well below the surface.  There is no putrid or garbage smell and no flies are attracted to this soil.

The buried bokashi fermented material was left alone for 14 days and then all of the soil was taken out of the plant container and filtered to collect any residual fermented food waste material that did not get processed by microbes.

Here it is very interesting because most of what you find is just soil.  In fact more than 95% of the material was completely converted to soil in just 14 days.  The only residual material evident at 14 days was the bones, a few grape stems and some fibrous stands of banana leaves that had been put in the fermenter.  I usually crush these with a stone and hammer just because I prefer not to have them sitting in the soil container but they would normally disappear in short time if left alone.  This is a matter of personal choice as it makes no difference to your plants.

200 pounds of Food Waste Fermented and then soil converted in 14 days

In summary, you can see immediately that if you pre-process the food waste using the bokashi (acidic anaerobic) fermentation process, the microbes in the soil in a very efficient way are able to completely degrade and convert that fermented waste to a rich nutrient soil.

If you live in a confined space but have enough room for a couple of plant containers, you can use one of the containers to process your fermented food waste and take that soil to put in other small or large containers that will support your beautiful plants.  No more stinky garbage, flies, rodents…..and very healthy plants.

If you have a garden you can do the same thing in the garden burying fermented food waste in the soil feeding microbes and your plants nutrients from your food scraps and wasted organic matter.

You may at first think this is almost magical.  And yes, it seems so surprising to the novice who knew nothing of bokashi fermenting processes.  However, the power and tribute here goes to those microbes.  They are highly capable and given the chance to extract energy most efficiently they will produce a great product for your soil.

They thrive in a special environment where few other microbes can compete.  In the acidic anaerobic dark fermenter they have evolved elegant and efficient ways of getting energy from your food waste.  They do it with enzymes and leave a banquet of scraps that your soil microbes will happily process when the material is put back to the soil.

We now know that bokashi fermenting is truly efficient and fast.  It takes food waste down to a stage that can then be rapidly processed in the soil.  This can not be accomplished if you just put food waste in the soil.  Those soil microbes need to have the material converted metabolically to a form they can then digest.

In Part 3 we will talk about yard waste processing and other commercial applications using the bokashi fermenting method of converting organic matter to soil.

  • This field is for validation purposes and should be left unchanged.