Bokashi
Scraps or organic materials fermented with an inoculum of microorganisms: a kitchen bucket, or a farm amendment.
Explanation
The word covers two related practices. At home, it is an airtight bucket where meal scraps ferment without air, with a bran inoculated with bacteria and yeasts; what comes out is a pre-compost, which is buried in the soil or finished in the compost (Washington State University, Kitsap County Extension). On the farm, it is an organic amendment made with a carbon source easily assimilated by microbes and a microbial inoculum, whose production and use Quiroz & Céspedes (2019) review, comparing it with compost.
Refined definition
Bokashi is not compost, even if it ends up in the same place: the bucket works by fermentation, without air, whereas classic composting breaks materials down in contact with air. On the farm side, the review by Quiroz & Céspedes (2019), published in the Journal of Soil Science and Plant Nutrition, finds that results on the inoculum speeding up mineralisation are contradictory, and that few studies link bokashi's nitrogen to crop yields.
Key points
The kitchen bucket
Scraps go into the bucket, are covered with inoculated bran and the lid is closed: it must be airtight, otherwise the scraps rot instead of fermenting (see the Advanced composting guide). The bucket also takes meat, dairy and cooked food. Once fermented, the contents are buried in a bed or mixed into the compost, where they break down within a few weeks (WSU Extension).
The farm amendment
According to Quiroz & Céspedes (2019), the nitrogen content of bokashi depends first on its raw materials: for a nitrogen-rich bokashi, you need nitrogen-rich materials and more of the readily assimilated carbon. The authors compare it with compost, taken as the reference amendment.
What remains to be shown
That the inoculum speeds up the mineralisation of organic matter: results are contradictory, and the interactions between the added microorganisms and those of the soil still need to be understood. That bokashi's nitrogen translates into yield: few studies have assessed it, alone or combined with other practices (Quiroz & Céspedes, 2019).
Watch out for
- • Wait before sowing or planting where the bucket's contents were buried: the Advanced composting guide advises two weeks.
Examples
- • A bokashi bucket under a flat's sink, emptied into a planter or the compost
- • Leftover meat and cooked dishes, fermented before going to the soil
- • Farm-made bokashi, compared with compost in trials
Sources
- Quiroz, M. & Céspedes, C. (2019). Bokashi as an amendment and source of nitrogen in sustainable agricultural systems: a review. Journal of Soil Science and Plant Nutrition, 19(1), 237-248.