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The Secret Sauce on Bokashi Composting

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Shredded vegetables

Almost 40-years ago, decades before soil microorganisms became popular, a Japanese scientist, Professor Teruo Higa, produced a mix he patented and called EM® – for Effective Microorganisms. These particular organisms have a low impact on humans. But what are they? EM® consumes toxins from the environment, pathogens from humans, and plant pathogens without harming humans.

The active ingredients of Bokashi, a Japanese term for fermented organic matter, are lactic acid bacteria (LAB), yeast, and phototrophic bacteria. LAB and yeast are also the key ingredients of Kombucha, known to improve the gut biome.

The third ingredient, phototrophic bacteria, harnesses solar energy for growth and metabolism. Its versatile metabolism, ability to adapt to extreme conditions, low maintenance cost, and high biomass yield make it ideal for wastewater treatment and resource recovery.

What is Bokashi Composting?

First, what is Composting?

Composting is essentially a process of propagating beneficial microorganisms on organic matter. While fermentation and anaerobic composting are often given a lousy efficacy report, done intelligently, both techniques can add significant value to soil.

Bokashi composting is primarily a process of breaking food waste down into a fermented mass. The process requires very little intervention. Adding the final fermented product to the soil and aerobic compost can produce a super-fertile growth medium. It can even be done indoors.

Effective Microorganisms (EM)

Bokashi creates a symbiotic effect by combining lactic acid bacteria, yeast, and phototropic bacteria. These microorganisms have a catalytic impact on present organisms in the soil, limiting the development of harmful bacteria and supporting the development of beneficial soil biota.

Infographic for the components and process of Bokashi EM

Bokashi Composting

Bokashi is an intensive method of composting. Effective microorganisms (EM) act as supporters of beneficial microbes that exist natively in the soil. The result is soil becomes richer, and plants grow healthier and more resistant to diseases and harmful insects.

Since the widespread introduction of effective microorganisms (EM), Bokashi is generally made using molasses, water, EM, and wheat bran (rice hulls, or even sawdust). It can use aerobic or anaerobic inoculation to produce the compost. Once a starter culture is made, it can extend the culture indefinitely, like yogurt culture.

In home-composting applications, kitchen waste is placed into a container sealed with an air-tight lid. These scraps are then inoculated with a Bokashi EM mix. The mix usually takes the form of a carrier bulking agent such as rice hulls, wheat bran, or sawdust. The bulking agent has been inoculated with concentrated, effective microorganisms.

Where Does Bokashi Come From?

Bokashi is the Japanese word for “ferment.” Professor Teruo Higa, a professor at the Department of Horticulture at the University of the Ryukyus, Okinawa, Japan, expands on EM thus:

The technology was initiated in the 1980s in Japan and was based on developing sustainable organic food systems. The success achieved in this field – both in crops and livestock, including aquaculture, led to its expansion into industries and even health.

 In the 1980s, Dr. Higa reported that a combination of around 80 different microorganisms could positively influence decomposing organic matter, causing it to revert to a life-promoting value. Effective Microorganisms are explained by invoking the ‘dominance principle.’ Dr. Higa proposed that microorganisms can be divided into three categories:

  • Positive microorganisms – responsible for regeneration
  • Harmful microorganisms – accountable for decomposition and degeneration
  • Opportunist microorganisms

According to Dr. Higa, the ratio of harmful and positive microorganisms is critical in all media (soil, water, air, the human intestines) because opportunist microorganisms follow the dominant trend.

It was initially proposed as a soil enrichment regime that has since evolved into many applications, including infection control, stain removal, and a pesticide.

Earth knows no desolation. She smells regeneration in the moist breath of decay.

george meridith

How To Make Bokashi Compost?

Up to now, we’ve paid a lot of attention to the EM part of Bokashi Composting. It is because EM is the magic juice. But EM is just a microorganism-rich liquid that can be used to inoculate bulking agents that will better (and more economically) spread the effective microorganisms. The bulking agents are usually carbon-based, but you can also use EM on cat litter to control odors and bacteria.

Depending on your personality type, you may wish to purchase Bokashi bran, or you may want to make your own. Making your own Bokashi Bran Is uncomplicated and economical.

Essentially you want to expand your EM’s availability. Your effective microorganisms need a place to live, transport, and food. Effective microorganisms need a material that offers a high surface area and is rich in carbon. Their most common substrate is wheat bran, but you can use rice hulls, shredded paper, or untreated sawdust as well.

Microorganisms need water for mobility. Water allows the ME to permeate the substrate fully. Preferably it would be better to use unchlorinated water.

Effective microorganisms consume carbohydrates. By adding molasses, or sugary water or beer will help your microorganisms grow and multiply. Molasses is good because it is inexpensive and is rich in other minerals. Sugary water is rich in carbohydrates, and beer contains uric acid that is rich in available nitrogen.

Bokashi Bran Ingredients

To make your bokashi bran, you will need the following ingredients and equipment. The rule of thumb is that you need a quarter of your wheat bran weight in water.

Helpful Conversions

  • 1 gallon is equal to 19 cups (19.2152)
  • 1 gallon of water weighs 8.345 pounds

Ingredients and Tools

  • 12.5-pounds of Wheat Bran (or Rice Hulls)
  • 1 cup of Bokashi EM-1™ (NOT EMA)
  • 1 cup of Molasses (or alternative)
  • 60 fl. oz. of warm water (120-degrees Fahrenheit) – preferably unchlorinated or de-chlorinated
  • Large mixing container (not washed in antibacterial detergent – wiped with diluted EM-1®)
  • A potato masher
  • A plastic sheet big enough to cover the container top. While many suggest using a refuse sack, don’t use antibacterial versions)
Infographic for how to make Bokashi Bran

Bokashi Bran Recipe

Step 1

Add the wheat bran or rice hulls to the mixing bowl. If you buy wheat bran in bulk, it ought to cost you just over 50c per pound for a 50-pound bag. Rice hulls are a bit more expensive. Wheat bran for worm farms is also a suitable alternative. The finer, the better, as we want maximum surface area. Because Bokashi composting is anaerobic, we don’t have concerns about compacting.

Step 2

Mix the Molasses, EM-1®, and water. Your water is one-quarter of the weight of your wheat bran (12.5 divided by 4 = 3.125 pounds of water) – which is 60 fluid ounces or just more than 7 cups. Remember, warm water (not hot) stimulates your effective microorganisms activity and makes it easier to dissolve the molasses (or treacle).

Step 3

Add your fluids to the dry ingredients. Thoroughly mix your water mixture in with the wheat bran, ensuring that you have no dry bits. If your bran stock is super dry, add additional water a little at a time. Do not let your bran mix get too hydrated. It has to be evenly damp, not wet, not dry.

Step 4

Remove as much air as you can. Use the potato masher to press your mix to the bottom of your bucket, removing air from the bucket. Use your plastic sheet (it could be a refuse bag) to isolate your mix from getting oxygen – pressing it slightly around the edges. The effective microorganisms in EM-1® do best in anaerobic conditions.

Step 5

Store in an air-tight container for two to three weeks. It is best to leave the newly manufactured untouched for a minimum of two weeks before use. The longer it stays in anaerobic conditions, the more your effective microorganisms get an opportunity to grow and multiply.

At some point, they will run out of carbohydrates, at which point they will become dormant (not die).

Step 6 (optional)

Optionally, you can dry the Bokashi Bran mix and store it for up to 2-years. You can do this by spreading the fully inoculated mixture on a tarp for the sun to dry it out.

If the weather doesn’t permit this, you can dry it in batches in an oven with the door open and the temperature set to as low as possible. You do not want to heat your Bokashi Bran higher than 120-degrees Fahrenheit.

Finally

Finally, you have a supply of homemade Bokashi Bran to use in your Bokashi bin. Every time you add kitchen scraps to the container, spread some Bokashi bran over the top.

Your effective organisms in the inoculated bran will break organic matter down and create a fermented mass. Feel free to add meat, bones, peels, and eggshells – your EM will break it all down safely.

Trouble Shooting Problems When Making Bokashi

During the process of fermentation, your Bokashi bin content will create a range of bacteria and fungi spores. The effective organisms that include lactic acid bacteria (yogurt), yeast, and a form of algae, will prevent the content from putrifying (rotting). There should be no foul smells.

What Could go Wrong?

Below is a list of things that may be cause for disaster.

Too much oxygen in the process

It is not possible to eliminate oxygen, but you want to keep it below 6-percent. Your effective microorganisms are allergic to oxygen. To do their job, you need to keep the bin closed and expel the air from the mix daily.

I use a potato masher dedicated to the job. After adding your food scraps and covering them with a layer of Bokashi Bran, press the mass down for the liquids to drain into the catch-tray and expel the air.

Water accumulation in the process

The step above is essential to minimize both air and water. To ensure no liquids accumulate in the bin’s bottom area, invest in a suitable Bokashi bin. You can cut its running cost by making your own bran, but don’t skimp on the Bokashi bin and EM-1®

A suitable Bokashi bin has a false-bottom topped with a grid that separates the fermenting materials from the drained liquids. This section is then fitted with a tap for you to drain the juices, which should be done every second day.

Bokashi Bran not effectively inoculated

If you make your own Bokashi Bran, you risk it not being effectively inoculated with effective microorganisms. Explanations as to why this happens are myriad.

To ensure your process is effective, make smaller batches initially. Document the adjustments you make to the mix. Record the day’s ambient temperature, humidity, and any other applicable variants.

Once you have a working pattern, stick to the basic plan, only making small changes and noting changes in your fermenting process.  Composting is both a science and an art.

Scrap pieces too big

It is advisable to increase the surface area of your kitchen scraps where possible. Try not to add pieces that are bigger than a cubic inch (medium button mushroom). Of course, you won’t need to chop your scrap bones up, but these may take longer to break down.

In my final fermented mass, I sometimes get bones and avocado peels. Still, these readily break down once I add the Bokashi bin content to my soil mix.

Effective microorganisms can’t get to their food source

For the EM to do their work, they need to be put at the worksite. When you add your kitchen scraps, it may be a good idea to sprinkle them with Bokashi Bran before you add them.

Alternatively, add a layer of about an inch or two and add two tablespoons of Bokashi bran to the mix. Stir the top layer to spread the bran as much as possible. You want the scraps to be lightly covered with Bokashi bran to speed up the fermentation and limit odors or pathogens.

Remember to press the mix down to remove any air and juices before sealing the lid again.

How Will I Know if My Bokashi Bin Fermentation Process is Failing?

Below is a list of indicators that you need to dump your Bokashi process and start over. When starting over, do not wash your Bokashi bin with antibacterial. Instead, use a clean rag soaked a solution (1:10) of water and EM-1®.

Black or Green mold on top of the pile

On top of your fermenting food scraps, you will notice white fluff that looks like light cotton wool. It is mycelia, the vegetative part of fungi and bacteria. The fact that it is white indicates that your batch is healthy and the EM are effectively active.

If your spores are black or green, the batch is putrified and needs to be dumped. There are no corrective measures that can be taken once purification has set in.

A foul smell is coming from the bin

The smell of the fermentation process is like mild cider. You are creating pickled food scraps loaded with organisms that will break the food down entirely once it’s added to soil, where resident microbes will finish the work.

If there is a putrid smell, your batch has gone off. This could be a result of any of the causes listed above. Some say their bokashi smells like vomit. I have never had a vomit-smelling batch, and my nose is super sensitive to smells.

My advice is to minimize fluid retention and trapped air pockets and maximize contact of microbes to food, as evidenced by Bokashi Bran spread.

Kitchen scraps are too wet inside the bin (water wet – usually at the bottom)

Bokashi bins come fitted with a drainage tap below the false bottom (below a separator mesh). The juice (sometimes called tea) that is drained is usually quite acidic and unsuitable for some plants.

The Bokashi tea is loaded with EM, and pouring a diluted mix down your drain helps manage foul odors and clogging. For plants that like a low pH, the tea is a great booster. These include:

  • Radish
  • Potato
  • Sweet potato
  • Parsley
  • Peppers
  • Rhubarb
  • Blueberries
  • Cranberries
  • Elderberries
  • Gooseberries

Ensure that water and air are expelled from the mix of kitchen scraps and EM to optimize the fermenting process. Excess water inhibits this process, as does more than 6% oxygen.

Using the “Compost” From Your Bokashi Bin

The fermented kitchen scraps from your Bokashi bin are not compost but a microorganism-enriched mass of readily decomposable matter. To create compost with the kitchen scraps from your Bokashi bin, follow these steps.

Store the sealed bin for two weeks before using

Once your Bokashi bin is full, add a final layer of Bokashi bran on top of the scraps and seal the container air-tight. Store it out of direct sunlight for an additional two weeks.

I have two bins for this very reason. While the one is in the final stages of fermentation, I use the second one for my kitchen scraps.  Alternatively, you can keep your scraps in a container in the fridge until the bin becomes available when you’ll add them to the bin. Remember to layer the kitchen scraps 2-inches deep and cover them with Bokashi Bran.

Making a Compost from Bokashi Fermented Scraps

Bokashi Trench Composting

To create a nutrient-rich garden bed, dig a furrow of about a foot wide and equally deep (12-inches) and a yard long. Using your wheelbarrow, add about two-thirds of the excavated soil and mix it with the fermented mass from the Bokashi bin.

When you open your bin, you may find it covered with white fungi spores (mycelia). This is an excellent sign that your fermented matter is healthy.

Mix the content in with the soil and use the mix to fill your furrow two-thirds full. Use the remaining ground to cover the mixed compost-to-be in the trench. The covered trench may stand proud, like a mound, but that is fine.

Leave the trench for a minimum of two weeks for the final decomposition to happen, after which you can use the area as a garden bed. The Bokashi will attract other beneficial microorganisms and soil biota that will significantly improve the soil quality.

Remember the principle of minimum tillage. Every time we dig the soil up, we disturb a delicately balanced system of soil biota. The Bokashi and soil mix (and if you added any other compost, good) will create a very healthy soil food web teeming with life.

While we directly enriched only an area of a foot-wide, those organisms will spread to adjacent areas if there’s water that aids their mobility. By planting on the trench and up to a foot on either side of it, you have a yard-wide vegetable bed with ultra-fertile soil. Not only is the soil more fertile, but it also has better water management abilities too.

Bokashi Indoor Composting

If you live in an environment where you do not have access to your own soil, Bokashi composting is a great solution. We all have kitchen scraps that can be transformed into valuable resources no matter where we live.

Having a Bokashi Bin will allow you to ferment your scraps hygienically and later convert the fermented mass into ultra-fertile potting soil. The best of it all, it can all be done indoors.

Ingredients and Tools Needed for Indoor Bokashi Composting

  • An air-tight 4-gallon bucket or bag (you can get commercial versions on Amazon)
  • A small bag of garden soil (not potting soil, which is too coarse)
  • A small bag of compost
  • A mixing trowel
  • A couple of newspaper sheets
  • (Optional) Dry builders sand or pebbles (enough to just cover the base of the bucket)
  • A large mixing bowl or tarp

Indoor Bokashi Composting Steps

Prepare your Container

Wipe your composting container (bag or bucker) with a 1:10 solution of EM-1® to remove any antibacterial residue on the inner surface. With COVID-19, the world has become super aware of microorganisms, and we’re killing much more than we need to, but such are the times we live in.

Provide a Way to Absorb Excess Moisture

Line the bucket or bag with a newspaper at to bottom to absorb any fluids. (*If there’s a specific article that irks your sensibilities, add it where it belongs – in the compost. It’s called maximizing the benefits)

If your mixture is very damp (it shouldn’t be), add dry builders sand or pebbles under the newspaper for additional absorption.

Mix Your Compost and Garden Soil

Using our tarp or mixing bowl, combine your garden soil and compost. The addition of compost adds diverse beneficial microorganisms that the EM-rich fermented mass will activate. A tarp is a handy addition to a home, allowing you a hygienic space to work on.

Talking about hygiene: EM-1® is an excellent alternative to antibacterial sprays, solvents, and soaps. It manages pathogens effectively and can remove stains. I have switched, and it works wonders for me. I’ve become a compulsive EM-1® dilution sprayer and wiper.

Let’s get back to the tarp and soil mix. Split the soil mix up into five parts. The reasons will become evident soon.

Mix the Soil and Bokashi

Fill the bottom of the container with a fifth of our soil mix. This part of the bucket will eventually become saturated with effective microorganisms through capillary action and gravity combined. It also prevents purification if there is too much moisture.

Mix the content from your Bokashi bin (that has been fermenting for at least two weeks) with three-fifths of the remaining soil mix. Add this to the container before finally adding the last fifth on top.

Seal And Store For a Month Before Using Your Ultra-Fertile Potting Soil

Before closing your bucket or bag, expel all the air by pressing down on the top of the mix. If you are using one of the commercial bags, I suggest you place it on a newspaper in case there is any seepage.

Store the bag or bucket where it is not exposed to direct sunlight. If you store the bucket on your balcony exposed to ambient temperatures, the following times apply. In the summer months, your ultra-fertile potting soil ought to be ready within a month. In winter, I would leave the bucket until early spring before using it – at least six weeks.

Is Bokashi Compost Better Than Standard Composting?

Well, yes and no. Bokashi composting is neither better nor less promising than standard composting – it’s just different. Below are some of the key differences between traditional composting and Bokashi composting.

MethodKey DifferentiatorBenefit
Traditional Hot CompostingFocussed on allowing the proliferation of aerobic soil biota, including bacteria and fungiWell researched and tested nitrogen conversion, pathogenic prevention, and moisture management abilities
Mold CompostingFocussed on developing fungi to break organic matter down, usually leavesCreates hygroscopic (moisture attracting and storing) organic matter that attracts other microorganisms that benefit the soil’s biota
Anaerobic CompostingThe purposeful reduction of living matter to a state of decomposition. It takes longer. It attracts residential microorganisms in the soil.Processes like trench composting are hassle-free (bury-and-forget) soil enrichment processes that attract microorganisms.
Fermentation CompostingUses carefully selected effective microorganisms to ferment fresh food for accelerated decomposition.Reduces anaerobic decomposition time significantly (12-times faster) while providing some control of the microorganisms’ specifics

Traditional Hot Composting

The compost you buy from a store or that which is created by home composting is generally made using an aerobic process involving carbon matter, nitrogen, water, oxygen, and heat. This process is often referred to as hot composting and has proven benefits.

By ensuring latent microorganisms have moisture for mobility, oxygen for health, and nitrogen for food, and by allowing them to get hotly excited, they multiply and consume the carbon-rich organic matter.

In the process, they make the nitrogen they consume available to plants (through a chain of events that includes other soil microorganisms).

If you want to maximize the benefits of the hot composting process, you will need to manage it. Ensuring the presence of moisture (to cool and to make the microorganisms mobile) and an adequate supply of oxygen (greater than 6%) requires some hands-on effort. It also requires timing, something that is less of a science than an art form.

The final product, once sufficiently cured, is loaded with microorganisms ready to bring every natural benefit to your soil and, by implication, your plants.

Good compost benefits the soil’s water management abilities, soil texture, and fertility. Compost tea helps control pests and diseases if sprayed on the plant’s foliage.

Mold Composting

Organic matter that is rich in cellulose and lignin is best degraded by fungal activity. Composting leaves is an example. By increasing the available surface area (shredding) and adding water and nitrogen, leaves break down to create leaf mold.

The resultant leaf mold is highly hygroscopic. Put differently, leave mold is a water magnet. Because it so loves water, it is better as a soil enhancer than as mulch. Used as a mulch, it may absorb moisture from the ground to satisfy its urge for it.

I use leaf mold as potting soil, planting directly into it without any further enhancements. Leaves are an abundant free resource. It only takes the effort of collecting and shredding them to make tons of highly fertile potting soils.

When leave mold is mixed into soil, the resident microbes are enhanced by the presence of carbon and nitrogen, further enriching the soil.

Anaerobic Composting

Anaerobic composting is used to manufacture biofuels. With in-vessel composting, the process often opts for anaerobic conditions. It extracts the methane produced, converting it to be used as an energy source.

At a gardener’s level, anaerobic composting would be path composting or trench composting. Both methods bury fresh organic material for a year, during which time local residential microorganisms will break it down. The result is a strengthened soil biota that befits both soil and plants.

Fermented Composting

The fermenting process is often, erroneously, compared to pickling your food scraps. Pickles are created using acids. Fermentation is a process performed by bacteria and fungi and involves sugars. Think of beer, wine, ginger beer, and Kombucha.

It fascinates me that in China, centuries ago, they discovered the benefits of lactic acid bacteria and yeast to improve gut health – Kombucha.

And then, in the seventies, Dr. Higa in Japan used these two microorganisms (and purple algae) to create EM® and the Bokashi concept. I wonder if the one was a seed to the other or whether it is coincidental?

While Bokashi is often referred to as a composting process, bokashi is the Japanese term for fermentation. The bokashi process produces fermented kitchen food scraps. The benefit of this process is the organic waste is loaded with effective microorganisms.

Dr. Higa’s proven hypothesis was that non-pathogenic (neutral) microorganisms would become beneficial if the cohort of microorganisms were inoculated with effective microorganisms. The abundance of effective microorganisms would irradicate pathogenic organisms.

So, when the fermented product is added to soil, the microorganisms in the soil are boosted “for good” to accelerate the decomposition process.

What usually takes about a year to decompose in an anaerobic environment (like trench composting), can now be done in a month (if you take the fermentation process into account).

What Volume of Compost Can Be Made Using Bokashi?

The availability of food scraps is the limiting factor. In environments like restaurants and food courts where there is much wastage, Bokashi is a great option. Bulk Bokashi fermenters will require regular draining, though this can be automated.

Add a food layer and sufficient Bokashi bran to cover the scraps, inoculating the mass with EM in the process. The addition of some cardboard containers will not negatively affect the process.

Holding containers must actively separate the fermenting scraps from water drainage, limit oxygen pockets, and be able to be sealed for two weeks.

To minimize the need for additional space, which for most operations are at a premium, once the bin is packed and sealed, it can be removed from the premises. The process of creating composting from the fermented food scraps can even be done in a warehouse.

In a domestic environment, the average household of three to four will fill the standard 5-gallon bin in two weeks. Such a household can produce 20-gallons (3.2 cubic feet) of compost per month.

In a year, it’s enough to create a fertile garden and provide fertile soil for all the house plants you could want – all from kitchen scraps that would typically be binned.

FAQ

Conclusion

Effective microorganisms (EM®) is a whole new approach to dealing with kitchen scraps – and it’s a wonderful one at that. With more than 40% of produced food going to waste, processes like Bokashi fermentation offer an opportunity to turn food wastage into ultra-fertile soil.

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