Overview of Bokashi

Fermented Organic Matter for large and small-scale uses

When I was first introduced to bokashi in 1997, it was only used to recycle food waste. It was usually made from rice or wheat bran and fermented with EM-1, EMX ceramics, molasses, and water. It was fermented in an airtight container for two weeks and dried into a crispy material. The bokashi was used in airtight buckets to ferment food waste from homes. After the fermentation, the fermented food wastes were added to the soil to help build soil health and feed plants. Sometime in the 2000s, the use was expanded into a type of fertilizer or soil amendment, where the main benefits were from the mycelium growth on the soil's surface.

This subject of bokashi sometimes confuses people due to the word being used for several applications. “Bokashi” is a Japanese word meaning “fermented organic matter.” In the EM world, it has several meanings. There are four general ways it is used: 1, as a fermented plant material such as wheat bran or rice bran; 2, as a fermented, or pickled, food waste using the bran as a fermentation starter; 3, as a replacement for fertilizer or compost by fermenting organic materials, including manures; 4, as a fermented feed for livestock, also known as silage.

Bokashi:  The Bran Product

In its simplest form, bokashi, or fermented organic matter, can be any dried plant material, molasses, microbes, and water allowed to ferment for at least 2 weeks. Below is the most common recipe for making bokashi with EM•1. This recipe comes from the APNAN manual, which two of the EMRO founders wrote in the late 1990s:

50# Wheat Bran or Rice Bran

¾ Cup EM-1

¾ Cup Molasses

~3 gallons of clean water

Mix the liquids into the bran until you can make a ball with the bran, but no excess liquid comes out.

Put the materials in an airtight container (a drum or plastic bag) and leave them to ferment for two weeks.

After fermentation, you can dry it or leave it “wet.” Dry bokashi tends to spread better than wet bokashi. 

After fermentation, this material is called “bokashi.”  Increasing the molasses and EM-1 to 1 cup makes for a stronger-smelling bokashi (a little sourer). The use of EM-1 in the recipe is what separates one bokashi product from another.  Remember, different microbes produce different metabolites. Therefore, if not using EM-1 to make bokashi, it will not have the same metabolites and perform differently. Some people prefer to ferment the bokashi for several months or years. They may also use EM ceramics in the water or add other ingredients to turn this product into plant food.

The market's most common types of bokashi are made with rice or wheat bran. Since EM came from Japan, where rice is a ubiquitous crop and wheat is not, one can say the original version of bokashi was rice bran. In the United States, wheat is more readily available. Therefore, in the US, it is more likely to find wheat bran bokashi than rice bran bokashi. Another common ingredient is spent grains from brewing facilities. There have also been stories from EMRO research staff who were on assignment in Egypt making bokashi with sand because they could not find any plant materials. While living in the Northeast, I often made bokashi for leaves in the fall and dried grass clippings. I have also consulted with some cannabis growers and taught them to make bokashi with the leftover plant material, allowing them to recycle all plant materials from their growing operation fully. Once in Nova Scotia, I did a class showing people how to make bokashi out of wood chips. In New Mexico, I taught several farmers how to make bokashi on a large scale, similar to windrow composting, but with only one turn to mix the materials and no need to monitor temperatures. Over the years, these farmers made well over one and a half million tons of bokashi with dairy manure and dried plant materials. They applied it to their fields, increasing organic matter and moisture retention. As mentioned above, any organic material can be used to make bokashi. Bokashi may be made with dried plant material, including biochar, coffee chaff, dried grass or leaves, etc.

Bokashi is most commonly made with EM-1, which contains a few fungal ingredients, including yeast and beneficial candida species (C. utilis and C. ethanolica). EM-1 itself does not contain any filamentous fungi. However, when using bokashi, one often sees a cotton candy-looking “fungal” growth in the bokashi itself or on the soil surface a day or two after it is applied. This “white stuff” was tested in a lab, and it turns out that it is a micrococci species commonly used to ferment sausages. We always thought this came from the bran since the micrococci are not in EM-1. It turns out that it likely comes from the people making the bokashi since they hardly use gloves when making the bokashi—the micrococci are found on human skin. In this case, the human touch makes the bokashi work better!

When ‘bokashi’ is bran, it can be spread on the soil to accelerate the breakdown of plant residue, making it a great additive after plants are pruned. This feature allows growers to prune plants, leave them where they lie, and let materials easily break down in the container or field. The applications of the bran supply microbes, nutrients, and organic matter all in one. These types of applications increase soil health, bringing all the benefits of improved soil health. There are other applications, such as the fermentation of food wastes, where food scraps are added to an airtight bucket and layered with the bran. The bran is a fermentation starter, essentially pickling food scraps and preserving their nutrients. After a two-week fermentation, the fermented food scraps are added to the soil. Bokashi fermentation prevents rotting and the growth of pathogens and is done in an airtight system; therefore, there are no foul odors when done correctly.

On a large scale, the making of bokashi is similar to making silage, a fermented feed used mostly for cattle. Silage is often made in bunkers, where tons of material are added and inoculated with microbes (lactic acid bacteria and sometimes yeast) and water. On dairy farms worldwide, silage is made to supplement the feed for the cattle in the winter months. Silage is made from several different types of green or semi-green plant materials, and microbes are added; then, the pile is covered with plastic, and the silage will reach about 70% moisture. Bokashi uses between 30% and 35% moisture to ferment. This same process can be used to create materials to apply to farmland. The fermentation preserves the nutrients of the ingredients. However, the nutrients are bioavailable after the fermentation is complete, resulting in a fertilizing material that does not leach or gas off, is loaded with microbes and their metabolites, and contains lots of organic matter to build soil. Depending on the ingredients, 2 to 4 tons per acre is enough to grow most crops.

Bokashi is a fermentation process and a product whose history goes back thousands of years. The use of bokashi would have nearly been lost were it not for Dr. Teruo Higa, the discoverer of EM, who added his microbial inoculant to organic matter to recycle food waste. Today, there are multiple companies making and selling bokashi products around the world, helping keep food wastes from landfills, providing education in schools, and helping to improve soil while providing nutrients, preventing erosion, and replacing the use of synthetic fertilizers.

Note: I plan to write more about bokashi here in the future. I am co-writing a book on bokashi that examines much of the scientific background and the history of this type of fermentation.