How to use Bokashi bran fermentations of kitchen waste to produce plant food -
A post from Bob Heyman - August 2022.
I've been using the Bokashi method of fermenting kitchen waste to produce plant food for about a year, and would like to share my experience.
Bokashi fermentation involves compressing kitchen waste in a small bin which has a tap and an airtight lid, covering layers with sprinklings of bran. You can buy a pair of buckets for around £45 including a starter pack of bran. The buckets should last indefinitely.
(The cat is shown to scale the picture of one of the buckets. She is not for fermentation!) You ferment any kitchen and garden waste, including fruit and vegetable scraps, citrus, meat, fish, dairy, eggs, bread, plastic-free tea bags and packaged food. Even bones can be fermented although it takes longer. You can also include garden waste. However, it's not recommended as there would be far too much to dispose of. Also, as explained below, it's a good idea to mix the mush which you get after fermentation with garden waste in a compost bin.
You compress the waste with the supplied tamper and sprinkle layers with Bokashi bran. You can replenish the bran with a bulk supply, although it is not cheap. I bought three kilos for £21.50, enough for nine month to a year, depending on how much is used. I haven't found any recommendations about amounts, but have found that putting in more generates more liquid plant feed. I tend to sprinkle enough to cover the surface of the compost thinly three times a day, after each meal.
You keep compressing your kitchen waste and sprinkling layers until no more can fit in. The volume of waste reduces to about a third of its original bulk. You periodically rack off the liquid which falls to the bottom of the bucket into a bottle. It is sweet smelling and you can get about half a litre in total from each fermentation.
When the bucket is full, you put it to one side for a couple of weeks, or until the second one is full, and start the process with your second bucket.
You end up with two products. The liquid is a concentrated plant food. According to the internet, it contains nitrogen, phosphorous, and potassium plus other nutrients (which may include boron, chlorine, iron, manganese and zinc) and microorganisms. It's highly concentrated, with a dilution factor of 1:00 recommended. I find that a canny dollop per large watering can seems to be about right. You need to try to keep it off leaves, but I haven't noticed any problems when they get splashed. You are supposed to use the liquid within a few days of bottling it, but I haven't noticed any problems in storing it for longer. Our household of two persons plus a cat produce enough more than enough fertiliser for two small gardens and two half allotments. The second product is an inedible odourless block of mush which can be buried in the garden or allotment, or mixed with garden waste in a composting bin, which is what I do. It shouldn't be put on the ground until it has broken down as it is initially too concentrated.
Is it worthwhile to make your own plant fertiliser from Bokashi bran? As with so many aspects of allotment gardening, it would probably be cheaper to buy chemical fertiliser, and would certainly save a lot of work. But it is very satisfying to make your own fertiliser. I have been using it on my gardens and allotments this year (2022). I have had magnificent crops, but, of course, that may be due to the hot sunny weather rather than the fertiliser! It is good to feel that you are making some use of waste food, e.g. bread, and there is no danger that rats or other pests will eat the residual mush in the compost bin. The main work is cleaning the bins. Once the whole process becomes routine, it's fairly effortless.
I will continue to ferment my kitchen waste, and have faith that the 'natural' fertiliser it generates is benefiting my crops!