Friday, December 14, 2012

Bokashi Composting, a fast, anaerobic, fermentation process

Gainesville Compost Chief Engineer & Inventor Steven Kanner
mixes bokashi grain into UF Krishna Lunch food waste.
A guest post by Chris Cano

(I ran into Chris recently at Porter's Community Garden. You can read about this at The Gainesville community behind Porter's Garden. He talked about this different type of composting, so I asked him to educate us. Thanks, Chris.)

Upon running into Ginny at Porters Community Farm, I was excited to share with her about our Gainesville Compost initiative, particularly about a new food scrap fermentation solution called bokashi which we have been experimenting with at the Porters plot.

While the Gainesville Compost initiative collects hundreds of pounds of food scraps per week, we have normally handled this by way of traditional pile composting and vermicomposting (using earthworms). Recently, we learned about the centuries' old Japanese bokashi method of composting, which uses anaerobic bacteria to ferment food scraps, thereby reducing odors, reducing the volume of waste, and preparing the scraps to be more easily digested by microbes in the soil or compost pile.

During last week's workday, while many of the volunteers planted fruit trees, we were working on another project: handling an impromptu load of approximately 1,000 pounds of cooked food from the University of Florida's popular Krishna Lunch program, which serves about 1,000 students a day on campus.

While we have handled Krishna Lunch's pre-consumer food waste for nearly a year, their post-consumer leftovers have been going to a pig farmer. On this day last week, the Krishna Lunch coordinator gave me a call with an emergency request: "We have 44 buckets of cooked food waste in buckets, is there anything you can do for us?" So we decided to help.

Our last bokashi experiment proved to be fruitful. The process, as described below, resulted in a 40-percent reduction in volume in one week, a 60-percent reduction in volume in two weeks, and a virtually odorless end product, which after one week in our compost piles has nearly decomposed completely.

To make/use bokashi:

1. Start with a grain substrate. In our case, we've collected spent grain from a local beer brewery.
2. Inoculate your grain with a culture of microorganisms commonly known as "Effective Microorganisms" or EM1. (We purchased our first batch, but now we are maintaining a culture for future use.)
3. After one week, mix the inoculated grain into a container of food scraps. We went with a ratio of around 1:10 parts grain to food scrap. Seal the container.
The liquid drained from the bokashi process
is a microbe-rich soil amendment.
4. Throughout the following week, you should drain the liquid, which can be used as a microbe-rich soil amendment. Draining the liquid helps to reduce the volume and weight of the material as well as prevent the process from going sour.
5. After a total of two weeks fermenting, open the container and you will likely notice a surprisingly odorless mix that has dramatically reduced in volume. You can apply this food scrap (which visually resembles its original state) to the garden by burying right in the soil, or to the compost pile where it will rapidly break down.

We are excited about using bokashi to improve our process. Bokashi has the potential to be a great urban composting solution (mainly because of its odor elimination), but also an amendment and soil builder for rural agriculture. In fact, we've got a waiting list of local farmers who are eager to try it.

Happy composting!

If you'd like to learn more about bokashi and receive updates on our progress, visit

Chris Cano is "Compost Experience Officer" (CEO) at Gainesville Compost, a pedal powered community compost network in Gainesville, FL, which works to turn waste into sustainable soil for the urban agriculture movement.

Green Garening Matters,
Ginny Stibolt


  1. How do you go about maintaining a viable culture? I'm an aspiring Biochemist and work in a lab with all the micro tools needed. I am going to purchase a bottle of the inactive EM-1 to start but would like to maintain a viable culture for future inoculations. Do you keep it dormant in the fridge indefinitely? When you are close to running out of the mother culture, do you make more by allowing it to grow then isolating the colonies?

    1. Hi Carol, our friend James who is helping us develop bokashi suggests this: "Take 1/2 gallon of water and bring it to a boil and 1/4 cup of molasses and three tablespoons of dried kelp or seaweed (can be gotten at most health food stores) in a tea ball or other way so that it is easily removable. Stir until the molasses is dissolved. Remove from heat and let cool to room temperature. Add 1/2 cup of existing culture and stir. Pour into an airtight container filling it 90% then cover it in a way that the produced gases will not make it explode, a air valve available at home brew shops works well but so does a balloon put on to the top."

      You can keep your culture going this way by producing subsequent batches. And yes, the fridge is an ideal place to store it, as suggested to us once by a professor at the university.

      Compost Experience Officer
      Gainesville Compost, The Bike Composters, LLC

  2. at what stage do you remove the teaball of kelp?

  3. i would take the kelp out. no reason for it.

  4. Very cool, sounds a bit like making sourdough bread!