Bokashi Composting System

By Russell Vinegar

What is bokashi?

Bokashi is a type of composting system that uses microorganisms to rapidly convert food waste into compost. The practice originated in Japan centuries ago, where farmers covered food waste with rich, local soil that contained microorganisms that would ferment the waste. More recently, bokashi been used successfully around the world at various scales, from single apartment units to entire cities.

Bokashi, like composting in general, is a way for us to ‘close the loop’ – to return the valuable nutrients stored in food waste to our soil, allowing us to grow more food in our gardens. More simply, it is also a way to reduce the amount of waste we send to landfill and save money by doing so. 

How does Bokashi work?

Bokashi composting is a two-step process. First, food waste is fermented or pickled in a sealed anaerobic (oxygen-free) environment by specialized microbes which are added to the food waste. The microbes, a mix of lactobacilli (the guys that make yogurt), yeast/fungi, and photosynthetic purple bacteria, are added to the food waste in ‘bokashi bran.’ Bokashi bran is made from a mix of wheat bran, molasses, and microbes.

After 7 – 30 days, depending on temperature, pickling is complete and the waste can be mixed into soil. While the waste won’t look much different, as anyone who has eaten a pickle knows, a pickle is a lot different from a cucumber. Chemical and structural changes to the waste material allow for rapid physical decomposition by soil microbes. In a week, little trace of the waste will remain and after two weeks the soil can be planted.

Why Bokashi? /// Why not regular compost?

Try as we might to reduce food waste, it is estimated that we produce 10.5 tonnes (23 000 lbs) of food waste each year at Camp Kawartha. Bokashi offers several advantages for us when it comes to managing that waste, including:

Outside of our developing bokashi project, most of our waste ends up in landfills, where it releases greenhouse gases and contaminates soil and groundwater. Food waste rotting in landfills produces methane, a greenhouse gas 72 times more potent than CO₂ over 20 years (and 21 times more potent over 100 years), and even composting produces CO₂. Bokashi fermentation takes place inside sealed barrels with almost no gas production; though, gas release once mixed in soil is unclear. Assuming similar greenhouse gas savings to composting, we’d save about 16 tonnes of CO₂ emission each year through bokashi!

Aside from the environmental benefits, the financial cost of landfilling clear. We spend roughly $6,000 each year on garbage disposal, and could save over $2000 of those expenses by taking food out of the picture. It is expected that our bokashi system will save us between $500 and $2,000 annually, depending on our specific management plan. Plus, we have been buying soil and compost each year to build our gardens and lawns, when we could be producing it ourselves.

Conventional composting was tried before at Camp Kawartha but bears were reportedly attracted, something probably contributed to by the amount of cooked food waste incorporated or improper management. Besides requiring intensive management, like turning and managing carbon:nitrogen ratio, not all foods can be composted.

One disadvantage with bokashi is the need to buy or make bokashi bran. This will cost $400/yr at full scale, but could potentially be handled ourselves in future.

For more information on bokashi, check out this page or come on out and take a tour of our system!