Bokashi composting can improve garden soil

Bokashi composting is an ancient method for converting agricultural wastes into useful soil amendments.  For centuries, asian rice farmers have processed their agricultural wastes by piling them in trenches.  Then they would cover the wastes with soil and fill the trenches with water.  The wastes would then ferment for some time.  Once the wastes were fermented, the farmers would add the compost to their fields.

It turns out that the “good soil” that they covered the wastes with contained important soil bacteria and yeasts.  When the water was added, anaerobic bacteria and other micro-organisms got to work breaking down the materials.  These bacteria would convert starches and other carbohydrates into inert acids, killed weed seeds and increased the bio-availability of nutrients in the soil.  The result is a rich soil amendment that any self-respecting gardener would be happy to dig into their fields, planters or garden rows.

What is modern bokashi composting?

There are many variations to bokashi composting.  If you go looking around you’ll find a wide variety of composting products that are designed to facilitate fermented decomposition.  The main requirements for a bokashi system are:

  • anaerobic bacteria (primarily lactobacillus casei)
  • an enclosure of some type or some way to restrict oxygen
  • organic material

Modern compost fermentation methods are used to process a wide variety of bio-wastes including raw sewage and animal manure.  Bokashi composting methods effectively kill pathogenic organisms present in these kinds of wastes and also kill seeds from potentially invasive plants.  Bokashi composting methods greatly increase the safety of using these kinds of wastes as soil amendments.

Basic bokashi composting method

Organic material is inoculated with bacteria, oxygen is restricted and the material will ferment.  Fermented wastes break down into the soil more rapidly.  For most people, bokashi fermentation systems work something like this:

  • Food scraps go into a bucket – The bucket should have a tight fitting lid and no ventilation.  Most bucket lids will release pressure that may build up due to fermentation.  It is necessary to be careful about lids that seal too tightly.  A pressurized bucket may burst, making a big stinky fermented mess.  Drilling a tiny hole (1/16 ” or 0.5 mm) in the lid will sufficiently release pressure without allowing excess oxygen into the container.
  • Inoculate the food scraps – There are many different ways to introduce bokashi bacteria into your compost.  Most people use bokashi bran, which is rice or wheat bran that has been partially fermented and then dried out.  Another method is to use a spray bottle of bacteria culture and occasionally spray the compost directly with the bacteria culture.
  • Bury the compost – After the scraps have fermented for at least a week at room temperature, they can be buried into the soil.  Fermented food scraps decay rapidly into the soil and generally do not attract the attention of animals or insects.  As the food scraps decay, the pH will gradually change from acidic to more basic.  If there are compost worms present in the soil surrounding the compost, they will move in and finish off the composting process.

It sounds complicated maybe, but it’s actually very simple.  The process safely and sanitarily converts food wastes into a useful soil amendment.

Origins of modern bokashi composting

In the 70’s, a Japanese college professor, named Dr. Teruo Higa, collected a culture of environmental lactic acid bacteria from a farm in rural Japan.  His methods and that bacteria culture are currently being used around the world for a wide variety of uses.

Chicken farmers are using the bokashi method to turn their potentially toxic chicken wastes into a safe, rich fertilizer.  Banana farmers and coconut farmers in tropical areas are converting their agricultural waste from a nuisance into a useful soil amendment.  Adding compost to the soil greatly increases soil fertility, which results in increased output and increased crop quality with reduced input requirements.

Benefits of compost in the soil

There are several ways that compost improves the quality of soil for agricultural purposes.  Adding compost to the soil increases soil permeability.  Increased soil permeability reduces fertilizer waste, reduces irrigation requirements and improves the over-all health of plants.  Generally, soil with compost will increase in productivity while soil without compost will gradually decline in productivity.

As soil permeability improves, water is more able to soak down into the soil.  As the water soaks into the soil, it draws oxygen and nitrogen down with it.  Because water soaks deeper into the soil, less irrigation is required.  Less irrigation means less run-off.

Roots of plants grow deeper in lighter, more permeable soils.  Deeper roots mean that plants are more able to endure stress and more likely to produce a healthy crop.  Also, deeper roots mean that plants are more able to draw nutrients from deeper in the ground.

Compost improves the ability of the soil to convert fertilizer to more useful forms for plant growth.  Compost provides some nutrient to the soil, but possibly more importantly, it reduces the need for chemical fertilizers by reducing waste.

Culturing Bokashi Bacteria

While it is possible to purchase a bokashi bacteria culture, it’s also simple and easy for most people to develop and maintain their own culture.  There are several videos that outline the process for you, showing the steps that are necessary to grow your own bokashi culture.

Bokashi bacteria culturing method

In order to grow your own culture, follow these steps:

  • Make your base – Mix sugar and water, or molasses and water, in a container with a mesh covering.  The mixture should only be slightly sweet.  Air should be able to reach the liquid, but insects should not.
  • Leave the base in a cool, well-ventilated space – The base will begin to grow all kinds of interesting stuff in it.  Only leave the base out for a 4 days to a week.  This is sufficient time to collect a culture of environmental
  • Once you have a successful culture, clarify the culture – If the base is covered with a black mold, throw it out and try again.  Clarifying the culture produces a culture that is high in lactic acid bacteria and low in opportunistic organisms, like pathogenic molds and yeasts.  These are the steps for clarifying:
    • Shake the mixture – Put a lid on the mixture, or put it in a closed container, mix it up
    • Ferment – Mix a small portion of the base with a larger quantity of fresh milk (1:10 ratio) and allow it to ferment.  Place it in a dark location that isn’t too hot or too cold for a week or two.
    • Siphon – After the mixture has fully fermented, there should be some separation.  The thicker part will float to the top and there will be some cloudiness on the bottom of the container.  The clear part in the middle is called “the serum” and contains a healthy population of bacterias and yeasts that are generally symbiotic, meaning that they work well together.  The easiest way to get the serum out is by using a piece of tubing to siphon it out.
  • Culture the ferment – Mix some of the serum with a fermentation mix and allow it to ferment for a week or so.  Keep a close eye on it to make sure it doesn’t build up too much pressure.  One recipe for a fermentation mix is:
    • 3/4 Cup unsulfured molasses
    • 1 Gallon water

A bokashi bacteria culture, collected and cultured in this manner can be used for many different purposes in agriculture.

Purchasing a bokashi compost bacteria culture

The most popular bokashi bacteria culture is EM1, a bokashi bacteria culture offered for sale by Teraganix.  It is also possible to purchase and use other common lactic acid bacteria products for bokashi composting.  Commercially prepared kefir, for instance, often contains 20 or more different strains of lactic acid bacteria.  Specifically, products that contain live cultures of lactobacillus casei are especially useful.

Developing a commercially available bokashi bacteria culture

Culturing a potential lactic acid bacteria culture is often as simple as introducing a sample of the culture to a container full of sugar water.  Unsulfured molasses and water is the preferred medium for a culture, but there are other possible sources for food for the bacteria.  The container and the medium (sugar water) should be reasonably sterile, especially since commercially available lactic acid bacteria products are often stored for long periods of time, resulting in a weaker bacteria culture.

Signs of a healthy bokashi bacteria culture

Within a few days, the culture should begin to show signs of fermentation such as:

  • Gas release – A properly fermenting medium may release a small quantity of CO2 gas.  This gas reduces the oxygen in the environment near the culture, and it may cause high pressure in a sealed container.  Especially when starting a new or fresh culture, you may want to use an airlock to reduce pressure, or leave the cap on loosely to reduce pressure build-up.  A tightly sealed container, with a fresh culture has the potential to explode, making a loud noise and a big mess.
  • Aroma of fermentation – A properly fermenting culture will have an aroma of fresh beer or fermenting apple cider.  Furthermore, it’s a warm kind of smell and it smells sort of like an old farm.
  • Settling –  If molasses is used as the culturing medium, then there will be some settling of particulates in the bottom of the container as the culture grows and develops.
  • Change in color – Molasses and water makes a very dark brown liquid.  As the culture grows, the color of the culture will lighten.
  • White film on top – A white film may form on the top of some cultures as time progresses.  This is a normal sign of a healthy culture.


Other uses for bokashi composting bacteria

The goal is to collect the lactic acid bacteria out of the environment and culture them for various uses.  A successful culture can have many interesting uses, such as:

  • Reducing odors – Bokashi bacteria cultures are useful for reducing all kinds of agricultural odors.  Mix a dilute culture (1:30 ratio) and apply to livestock pens, manure piles, septic pools/tanks etc.  If the bacteria is effective against that specific odor, there will be an immediate marked difference and a continued, long-term benefit.  For particularly intense odors, an increase in the quantity of culture may be required.
  • Preserving forage – Traditional silage methods can be applied to various types of forage to increase digestibility and facilitate storage using bokashi compost bacteria.
  • Fermenting foods – Live culture foods, like sauerkraut, kim chi and kefir have been made for centuries using similar environmental lactic acid bacteria and other symbiotic organisms.  The use of bokashi bacteria cultures is merely a slight variation from the traditional methods used.

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