Bokashi Composting: How Does It Work?

With more and more states in the US turning to more sustainable waste management methodologies, bokashi composting is gaining a lot more traction. People are searching for ways of disposing of their food waste more responsibly.

But what is the bokashi method? Is it better or worse than traditional composting or vermicomposting? What exactly are these “effective micro-organisms” and is there a huge benefit from using them? Is it difficult to do? Does it have a foul odor? Does it produce compost tea?

We’ll answer all of these questions and more today in this in-depth discussion of the bokashi process. There are a lot of methods out there to turn your kitchen waste into garden gold, and bokashi compost is just one of many potential options!

What Is Bokashi Composting?

In a nutshell, bokashi composting is a way of turning your food scraps into fermented organic matter that you can then add to your compost pile, bury in garden beds, or feed to red worms. Proponents of the system developed by Dr. Teruo Higa regularly claim that the leachate produced in this anaerobic process is a nutrient-rich tea, and they also claim that the fermented material produced is an excellent fertilizer.

During the 1960s, Dr. Higa was studying horticulture at the University of the Ryukyus in Okinawa, Japan. Studies were being done on microbiology and its effects on horticulture, and reputedly by accident, he discovered a combination of beneficial microorganisms that he believed stimulated growth in plants. After graduating and then completing his doctorate in horticulture, he was invited back to the university to become a lecturer in 1970. Two years later he became an assistant professor, and then a full professor of horticulture for the university in 1982.

Most of his studies have revolved around the effective microorganisms that he discovered and how they could be implemented in agricultural use. His initial formula, named EM-1, is used as an inoculant for bokashi bran used in the process of bokashi composting, along with other agricultural uses.

The process itself is a form of anaerobic fermentation. Waste is placed into an airtight container, typically with either a false floor to allow drain-off of bokashi juice (leachate) or with a secondary container beneath it to catch leachate. Bokashi bran is added to inoculate the bokashi bin with specific strains of beneficial microbes.

Once the bucket is full and layered with inoculated bran, it is topped off with a final layer of bran and sealed for at least two weeks to allow fermentation to occur. While the fermentation process usually takes about two weeks, it can be allowed to go for longer. Excess bokashi leachate is drained off. After that, the resulting material is considered bokashi pre-compost and needs to move into the next stages of decomposition using other methods.

The term “bokashi” is a Japanese word, believed to mean “fermented organic matter”. However, there is a secondary meaning in Japanese that relates to artwork, and some believe that the artistic reference to shading also can be translated as “fading away” – a term that can also be applied to the bokashi fermentation process.

What Are Effective Microorganisms?

There are a number of cultivated microbiological strains that are developed to make Dr. Higa’s EM-1, as well as his later variation EM-5. Among the most common are Lactobacillus, Saccharomyces, and Rhodopsuedomonas bacteria.

We know lactobacillus as the family of bacteria that helps us to make probiotic-rich fermented foods like kimchi, sauerkraut, or yogurt. There are a number of different bacteria in this family that are widely cultivated. Lactobacillus strains break down proteins extremely well.

Saccharomyces is the family of fungi from which yeast originates. These consume proteins and sugars, breaking them down very effectively and aiding fermentation.

Finally, Rhodopseudomonas is a common soil bacteria family. One specific form breaks down lignin, a common component in woody material, and this bacteria is a common addition to a bokashi inoculant. 

While the exact combination or quantities of bacteria in EM-1 are a carefully-guarded trade secret, it’s known that these are all major components of the blend used in a bokashi system.

What Is Bokashi Bran?

While it’s possible to use liquid EM-1 to kickstart your bokashi compost, most people prefer a method that doesn’t require you to keep a spray bottle on hand. This is where bokashi bran comes into play. Using organic materials like spent beer grain, wheat hulls or bran, oat bran, or rice hulls as a base, they inoculate the organic material with the beneficial microbes and then allow it to dry. This puts the bacteria into a state of stasis and allows for easy, complete application over the surface of the waste.

Some forms of bokashi bran use waste products as their base of choice, such as spent beer grains that would otherwise go into the waste stream. While these can also undergo traditional composting methods, they make a handy dry product that’s easy to sprinkle over the surface of the food waste you want to ferment. 

It is common to sprinkle bokashi bran on the bottom of the bokashi bin or bokashi bucket first, then add food scraps, layering bokashi bran every inch to two inches through the bokashi bucket. Once full and packed down to ensure a truly anaerobic process, a final layer of bokashi bran is added on the top surface before the bokashi system is sealed to allow fermentation to occur.

Is Bokashi Composting Really Composting?

In traditional composting systems, your food scraps are mixed with carbon-dense materials like wood, straw, shredded paper or cardboard, and so on. These will be layered in a compost pile or bin or added to a compost tumbler system. Typically, a ratio of 2:1 is a good baseline; two parts of carbon-dense materials to every part of nitrogen-dense food waste. Water is then applied to dampen all of the materials in the pile.

In your compost heap, the feeding of microbial life will heat up the contents of your composting bin. Turning it aerates it and ensures that the aerobic, or oxygenated, microbiology can thrive and break down your waste products. Over time, traditional composting produces usable compost that can enrich your garden.

Another form of composting is vermicomposting, or the use of a worm bin to break down kitchen scraps and organic waste products. This composting method is slightly different from traditional composting in that it’s intended to be a cold composting process so the worms used will thrive. In return, they produce worm castings or worm poop, a really useful amendment for garden beds. 

However, bokashi differs from traditional composting in that your food scraps don’t really turn into another product. While the organic materials you add to your bokashi system do change, they change via fermentation. Rather than breaking down through a standard composting process or being consumed by red worms, the material in your bokashi bins is just fermented. It has a faint aroma of pickles but is still completely identifiable as what it was before.

Why, then, would someone want to spend time with bokashi buckets only to get bokashi waste in return? There are a few different reasons for this. For one, bokashi can handle meat and dairy products. In most traditional compost methods, it’s common to try not to compost meat as it can be very smelly and may attract pests or predators to your compost bin. And, for many apartment dwellers, they are limited in the ability to have a more standard compost heap. Some may be squeamish about the idea of raising earthworms to consume their waste products. Bokashi can be done even in an apartment, making it a viable home composting method for small-space dwellers. 

Is Bokashi “Tea” Useful?

So far, studies done on leachate, often called “bokashi tea,” have been inconclusive about whether it’s beneficial to plants or not. Most studies show no real significant benefits for plants from applying the liquid to your garden. However, you will add beneficial microbial life to your soil, which may be a benefit over time.

This does not mean that the bokashi “tea” is useless, however. A recent study indicates that it may be of use in improving feed for farmed fish such as tilapia. In addition, many of the bacteria that are part of an EM solution can be effective at cleaning drains by breaking down stuff stuck to the inside of the drain system. There are potential benefits to adding it to septic systems as well, as the bacterial strains should aid in the decomposition of human waste just as they would aid in the breaking down of food.

How Does Bokashi Composting Work?

While we have done an in-depth description of this process in a prior piece on DIY bokashi buckets, let’s go over the basics of a typical bokashi process!

Filling The Bucket

You will need a bokashi bucket. If you want to DIY one, read that article I just mentioned on building a bucket. There are other consumer brands of bokashi buckets available on the market as well.

Begin by putting a layer of bokashi bran (in the kit form I just mentioned, it comes with your package) in the bottom of the bucket. Then, add scraps of organic materials. This can include yard waste, dairy products, meat products, coffee grounds, eggshells, and more. 

Avoid adding material that has already started to develop mold, as it is already bacterially active and could take over your bokashi. In addition, we do not recommend adding large bones or oil to the bucket, as both take a very long time to break down and will remain wherever your pre-compost ends up later. Finally, we do not recommend adding pet feces to this system as they are also microbially active and may not be properly fermented using this process.

For every inch or two of organic material, add more bran to the bucket. Use a potato masher, spoon, or something firm to tamp down the organic matter in the bucket, eliminating any air pockets that may exist. If you don’t have enough to fill the bucket all at once, seal it completely and wait until you have a full kitchen compost pail to add, then repeat this process. 

If your bucket comes with a drain, empty out any leachate that forms in the bottom of the bucket as the material starts to break down.

Fermentation Period

When your pail is full, add more bokashi blend across the entire top of the bucket, then seal the lid. If your pail has a drain spout, continue emptying leachate, but otherwise, leave the bucket to ferment for 2-4 weeks. The longer you leave it fermenting, the more the food scraps will be weakened by the bacteria. Some people opt to have two bins so that they can fill one while the other one is undergoing fermentation. 

Try to keep your pail out of direct sunlight while this process is underway. This is more to ensure that the combination of fermentation and heat doesn’t cause the lid to pop off than from any risk from the sun itself.

Burying The Ferment In The Garden

Finally, when fermentation has concluded, it’s time to take the pre-composted material and put it to use. Dig a deep hole in the garden and bury the bokashi in it, making sure to mix soil through the food remnants thoroughly. If you do not have a garden but have access to a community garden, you may be able to bury it there as well. The remnants of the food, now exposed to soil microbial life, will be rapidly broken down, and the nutrients contained in them will become part of your garden soil and become accessible food for your plants.

If you live in a cold climate, it is possible to store buckets of bokashi through the winter months and then bury it in garden beds once the soil thaws in the spring. Allow at least two weeks between burying the remnants and planting out the beds, as this ensures that the acids from the fermentation process do not burn tender plant roots.

Soil Factories And Alternative Methods

Don’t have access to a garden? Do not panic! There are other methods you can use.

A large box of garden soil on a balcony can become your “soil factory.” Make certain it has some typical dirt from the yard in it, as that ensures it’s got some of the soil microbial life you need to break down the food remnants. Bury the bokashi in there, thoroughly covering it with soil, and let nature do the rest. Within a couple of weeks, you should not be able to find much, if anything, left of your kitchen scraps. You can then use that supercharged soil for potting up house plants or blend it with regular compost to make a good potting mix for larger outdoor container plants.

If you have access to other composting methods, such as a compost pile or worm bin, bokashi can be added to both of these methods. With a pile or in a standard stationary compost bin, make sure to cover the bokashi thoroughly with brown organic materials. Limit the quantities you feed to your vermicomposting bin to small amounts at any given time, but the worms will happily eat your trash! 

Remember that any bones from meat you may have added will take much longer to break down, so it’s best to avoid large bones. Small bones from fish will break down relatively fast, but big beefy ones can take years to completely vanish.

Who Should Do Bokashi Composting?

While it’s a multi-step process, this composting method is particularly suited for people who live in small spaces like apartments. It originated in Japan and is widely used throughout that country as well as other Asian countries where living space is at a premium and composting can be difficult.

But if you have a lot of stuff to compost and you want it to appear to melt away into the garden, this may also be a great option for you. You will not have a finished material that you can store and then use, as you would with regular compost, but you can still practice sustainability and ecologically-minded management of your household garbage – and that’s just as good!

Frequently Asked Questions

Q: Is bokashi better than composting?

A: It depends on your goal. If you’re looking for compost to blend into soil mixes or to use as mulch, no. If you’re looking to reduce what goes to your local municipal waste-management facility, it’s a great option.

Q: How long does bokashi take to decompose?

A: Once the contents of the pail have fermented and you have buried the precompost, it typically takes at least 2 weeks to break down. Large volumes can take a bit longer.

Q: What can you not put in bokashi?

A: We recommend not adding large bones, lots of liquid oils, moldy food, or pet poop.

Q: Do rats like bokashi?

A: Like all scavengers, they will happily take a nibble of bokashi. If you bury your waste deep enough, this is not a problem. A depth of at least a foot is recommended.

Q: Do worms like bokashi?

A: Absolutely! Most earthworms will find bokashi compost to be positively delicious. However, bokashi tends to be a bit acidic, so feeding your worms bokashi in moderation is recommended.