This year I am grateful for a new type of compost I have been trying that allows me to add dairy, meat, bones, and cooked or processed foods. These items are traditionally inappropriate for hot compost piles because they take longer to break down and attract undesired visitors to a compost pile. These materials become acceptable in a fermented compost – a technique called Bokashi composting.
Bokashi compost is a concept developed in the 1980s by Dr Teruo Higa of Japan while studying essential microorganisms. According to Dr. Higa’s “Beneficial and Effective Microorganisms for Sustainable Agriculture and Environment,” essential microorganisms exist everywhere, especially in soil and water and require a diverse balance to work. They are common in pickled and fermented foods and break down sugars and other complex organic molecules into simpler compounds that become more accessible to plants and other living things. For example, lactobascillus prevents pathogen growth and is found in yogurt, sauerkraut, and kimchi. Yeast breaks down sugars and is common to bread baking. These along with photosynthetic bacteria assist decomposition and contribute to the fermentation process of bokashi.
Traditional compost is an aerobic exercise, meaning it requires air flow or the horrible smell of putrefaction will set in. Fermentation is an anaerobic process, which instead creates a low oxygen, acidic environment allowing essential microorganisms to thrive and break down organic matter. Just as homemade pickled goods must be sealed, so must bokashi composting be completed in a sealed airtight container. Therefore, fermented compost will not smell rotten, but sour, pickled or yeasty in nature.
Essential microorganisms are applied to compost material through bokashi bran which may be purchased or cultivated at home with some patience. Bran is made by inoculating a carbon material such as spent beer grain or rice hulls with a liquid concentration of essential microorganisms and a sugar slurry to feed them. The product is then dried and stored in opaque packaging since UV light can deteriorate the product. The bran acts as a starter to ensure your compost receives the beneficial microbes that will colonize and ferment your compost scraps.
The process works like this:
In a bucket that has a spigot or drainage holes nested in another bucket, add a significant layer of carbon material at the bottom (shredded cardboard, newspaper, leaves, etc.)
Add finely chopped food materials in 1-2 inch layers and sprinkle at least 2 tablespoons of bokashi bran on each layer.
Tamp down each layer before adding another to reduce air pockets.
Apply a plate, plastic bag or cardboard to help seal air out & keep contents compressed with a heavy rock or brick. Secure air tight bucket lid, such as a gamma seal lid.
When your bucket is full, leave it for 2-4 weeks to finish fermenting.
After this time you will have pickled compost or pre-compost. Items will still be identifiable and not completely broken down yet. You can use it in the follows ways:
Trench Method: dig at least 6in into a garden bed and mix in your pickled pre-compost and cover with soil. In 2-4 weeks it should be mostly broken down and amended into the soil.
Soil Factory: In a storage tote add a layer of exhausted soil from planters or containers. Add your pre-compost and cover with more soil. Wait a few weeks for the soil to revitalize.
Add to your regular compost pile
Add to your vermicompost in small quantities.
The leachate gathered in the bottom of the bucket through the drainage holes is a mild fertilizer that can be diluted and used as a foliar spray or added to soil. This can be poured, drained, or basted out of the bucket.
It is important to remember that composting can be experimental in nature and may require troubleshooting at times. Be sure to check on your compost and drain at least weekly and try to add your scraps in big batches to reduce air exposure. Bokashi composting will smell yeasty, pickley or sour. If it smells putrid or rotten there is an imbalance. White fuzz is good and means the microbes are working. Blue, green, black, mold or fuzz means an imbalance of microbes. Generously add more bokashi bran in these instances. Pet feces or overly moldy food are not recommended in bokashi compost because they are overwhelmed with competing microbes. If your bokashi is wet, add more dry carbon materials to absorb moisture. Maggots may occur in moist conditions and are harmless.
While bokashi bran can be made at home, it is also a science experiment to be closely monitored. There are many tutorials available online and on YouTube in executing your own sustainable supply of essential microorganism inoculated bokashi bran. It is easily purchased online, though. A 2lb bag of bokashi bran goes for about $15-20 and will last up to approximately six months. This will depend on how much food scraps are added to a bin, how often, and your ideal amount of bran added. Thus, results may vary. When selecting a bokashi bran seller, remember opaque packaging ensures a longer lasting product. This author encourages purchasing from a seller that diverts industrial waste – such as spent beer grain- and supplies robust educational materials to learn from.
Bokashi compost is friendly to small living spaces, breaks down more complex types of organic matter in a shorter amount of time than a traditional hot compost pile and is a fun way to connect with the world of microorganisms. If you’re in the mood for a new garden related experiment, try it out and see how it works for you.
