Bokashi Compost

Technical articles - Living soil agronomy, Biodiversity

Polyculture-livestock Soil regeneration Compost

Bokashi composting ("Well fermented organic matter" in Japanese) is a Japanese method of composting organic waste in a anoxic environment. It has many benefits such as a greater amount of recyclable organic waste, a significant supply of nitrogen and organic matter (OM), and a shorter waiting time before application.

Principle

Bokashi is a method of fermenting organic matter in an anoxic (oxygen-free) and moist environment. This is its main difference from traditional outdoor compost which results from oxidation of organic matter in an aerobic environment.

The absence of oxygen allows avoiding CO2 emissions into the atmosphere, so almost all the energy and carbon from the starting material can be preserved and returned to the soil. ^[1] The Bokashi pile does not heat up.

It is possible to make Bokashi compost with virtually any organic waste : manure, green waste (fresh or dry), crop residues, solid phase of slurry, kitchen waste, etc. The only wastes to monitor in this case are lignin-containing elements, such as dead branches and wood, because they ferment less well. These should be moderately present in the organic waste mix and in the form of wood chips (RCW).

The fermentation process also produces bioactive molecules (antioxidants, natural antibiotics, organic acids, vitamins, enzymes…)^[2].

After three days, the farmer can use the liquid phase, called fermentation juice (rich in nitrogenous matter NH₄⁺) as fertilizer and the solid phase of the compost as a source of organic matter and bacteria.

Composting

Several methods exist to make Bokashi compost depending on the producer's context :

On a designated area

On a flat concrete surface (with the same characteristics as for wet silo ensiling), place one ton of organic waste.
Spray over the entire surface 2 l of diluted inoculants in about 10 l of water, depending on the dry matter content of the starting material (the pile should contain between 50% and 70% dry matter). The water addition allows microorganisms to move and fermentation to start. However, excess water could lead to putrefaction. The inoculants initiate fermentation and direct degradation towards maturation of the material. They then help restore a microbiological balance in the soil, via the principle of dominance.

The inoculants used are mainly lactobacillus-based: Bokashi bran, whey, Fermented Forest Litter (LiFoFer), Effective Microorganisms (EM). Depending on the preparations, some inoculants provide much more diversity than others. For example, a bamboo forest litter will have a diversity of lactobacilli different from a classic LiFoFer or whey. It is necessary to respect the dose of 2 to 3% inoculants to spray on the compost for effective fermentation. Simply convert the volume of inoculants needed in water according to the compost volume.

It is essential to work layer by layer, trying to mix the different organic materials as well as possible if there are several, and to distribute the inoculant solution evenly.
Compact the organic matter as much as possible to expel air (similar to ensiling).
Cover the compost and seal it hermetically to maintain an anoxic environment.
After three days, the fermentation juice will drain from the bottom of the compost : collect or drain this juice with a gutter. This fermentation juice can be used to supply nitrogen, manganese, and assimilable iron to the soil. It should be diluted to 10% of its volume in water, for example 100 ml of juice per 1 l of water. It can also be used to make an aerated compost tea.
The compost temperature must be below 35 °C, 40 °C maximum. Beware, too large temperature variations can compromise fermentation.
Bokashi must ferment for 8 to 10 weeks before it can be spread. Spread moderately or (ideally bury) the compost on the plot.

In a stable

Same method as above, except here it is possible to spray the manure and dirty straw directly with inoculants at 2-3% volume in water.

In sausage form

Using an agricultural bagger such as Feed Tuber, it is possible to compost organic waste with inoculants and put the compost "in sausage form" to move it more easily later.

In Bokashi containers

Bokashi composting is done in suitable containers for composting food waste.

Spreading

Bokashi is spread at a rate of 30 to 40 t/ha/year using a standard spreader.

Ideally, applications are made in autumn or spring, at least 2 weeks before planting the crop.

For pastures, the ideal is to apply Bokashi in autumn. Bokashi is not harmful to animals, however, to allow the grass to fully benefit from this input, it is recommended to remove animals from the pasture.

Applications

Bokashi composting is a method applicable in several agro-food spheres :

Farmers, livestock breeders : The ideal bases for Bokashi are slurry and straw, but all organic waste from a farm can be used (crop residues, plant waste…).
Horticulturists, market gardeners : It is possible to make Bokashi from foliage, weak fruits or vegetables, flower bulbs, etc.
Horse breeders : Horse manure is an ideal resource.
Agro-food industry / Retail : Plant waste (sorting rejects, downgraded, unsold…) is abundant and can also be valorized as Bokashi.

Advantages and disadvantages

Advantages	Disadvantages
Faster acting nitrogenous matter. Significant carbon storage to spread. Possibility to promote or even recreate soil biodiversity to strengthen soil-bacteria-plant exchanges in fundamental nutrients for plot fertility and productivity. The tarp prevents loss of composted material in case of rain or wind and reduces pollution risks. No greenhouse gas emissions. Requires less labor than traditional compost.	Acidic pH. Sensitive to temperature variations.