Bokashi composting

Bokashi Composting

We're going behind the scenes in one of our 'engine rooms' where activities that support the garden take place, such as processing staking material and composting. I'd like to show you our thinking and methods around this crucial aspect of gardening.

We've long used a 'cold composting system', piling up all our herbaceous material in a big heap and leaving it for a year to slowly rot down. By then it's nice compost but still contains weed seeds and has some limitations in the garden.

We've been trying to improve our composting and have tried compost cakes, the Maye Bruce method, and bokashi. Bokashi is the one we've adopted, as it composts with minimal inputs:

• don't have to turn – reduces effort
• doesn't lose its volume – produces much more compost
• releases much less carbon dioxide because it's a closed system
• can be done on a small scale at home.

Bokashi is a fermentation process, which is anaerobic, unlike traditional composting, which is aerobic and needs air to break down the material.

Process

1. Lay a large plastic sheet on the ground – this can be reused every year, so take care not to accidentally pierce it.

1. Cut the material up small to speed up the process. You can use anything – woody, herbaceous, or seedy weeds – it will all be broken down.

1. Dilute the effective microorganisms activated (EMA) solution to about 25ml in a 9l can of water, or as per the instructions.

1. Put down a layer of material on the sheet, leaving a margin around the edge. A pitch fork or dung fork is ideal for this.

• With normal composting you ideally put it in different layers, but the carbon-nitrogen ratio isn't so important here, so you can mix it all together.

1. Once the layer is a foot deep, dress with EMA activated solution using a watering can with rose.

1. Add a second layer on top.

1. Sprinkle ground seashells over the second layer. These are used to make the end product more alkaline, which is better for plants.

1. Continue to build up layers, watering EMA solution over every layer. Make as many layers as you have material for – this can work on any scale.

• It doesn't matter if the material is already starting to decompose – you can store it until you are ready to make the bokashi pile all at once or build layers up gradually as and when you get material. If doing this, just put EMA solution on top and cover it over, and uncover when ready to add another layer.

1. Squash down by trampling to get as much air out as possible and maximise the amount of material you can pack in.

1. Fold the edges of the sheet in to seal and roll it over to hold in place, making it as airtight as possible.

• You can make these any size you want, but a sausage shape works well.

How Long Before It Is Useable?

• Look and see if it's ready after 8-12 weeks.
• Check there aren't big bits of wood; if there are either leave it for longer or just sieve before using.
• Putting the woody material through a mulching machine first would make it ready sooner.

Don't Be Daunted

The early results of using bokashi here are looking very positive. It can feel like a lot of information to take in, but it's well worth giving it a go.

Using Bokashi with Kitchen Waste

You can do bokashi on a small scale with a bucket system. A bokashi bucket comes with a grate and a plug to tap off the liquid produced, and a bran that already has the EMA solution on it.

Process:

1. Put all your kitchen waste in, building it up in layers, sprinkling the bran on, all the way up to the top. Tamp it down to fit in as much as you can.

1. Seal tight when finished.

1. Every couple of days, tap off the solution and use it as a foliar feed.

1. After two weeks, the material can be mixed into borders or pots or added to the compost heap.

Glossary

Anaerobic

A process that takes place in the absence of oxygen.

Aerobic

A process that takes place in the presence of oxygen.

Bokashi

A Japanese composting technique that works by breaking down organic matter such as garden and food waste without oxygen (anaerobic fermentation), unlike traditional composting, which is aerobic (using oxygen).

Compost cake

A method of layering herbaceous and woody material in a specific way to ensure the pile decomposes on its own in around six months without a need for turning.

Effective microorganisms

A blend of beneficial microorganisms, such as naturally occurring bacteria and yeasts, that promote beneficial microbes, improve soil health, increase nutrient availability and suppress harmful pathogens. In activated form (EMA – a solution in which the effective microorganisms are fermented with molasses), they are used to improve soil and in bokashi composting.

Fermentation

A biological process in which microorganisms break down organic matter, like carbohydrates and sugars, to produce energy.

Foliar feed

A diluted liquid feed sprayed directly onto, and absorbed through plant leaves.

Leachate

A liquid that forms when water or another liquid drains through solid matter and extracts and carries some components of that solid with it. The term is often associated with contamination and pollution, but in a bokashi bucket system, the leachate is the nutrient-rich bokashi 'tea' that you tap off and use to feed your plants.

Maye Bruce composting method

A 'quick return' composting system, invented by Maye E. Bruce in 1935, that produces compost in weeks without a need for turning by inoculating the heap with an activator.

Windrow

Material heaped up into a long line, traditionally hay, so that it can dry in the wind.