Bokashi

Bokashi composting is a great way to break down kitchen waste fast and improve the nutrients in your garden soil.

What is it?

Bokashi composting is an anaerobic form of composting that uses effective microorganisms (EM) to ferment the organic waste.  As air is not required for the organic waste to ferment, this means that the bin is sealed off.  The process of fermentation is odor free and the bokashi bin can be used indoors – perfect for the kitchen.

During fermentation, some liquid will drain from the organic waste.  This liquid can be diluted with water and used as fertiliser in the garden.

Once fermentation of the bokashi mixture is completed, the contents look much like the original organic waste, but they are now broken down into the type of nutrients that the plants can use.  If the mixture is added to the soil, it can take 4- 8 weeks to break down completely into the soil, but it does not require any additional work (turning and aerating) during this time.  Just simply dig a hole in the garden, add the fermented waste and cover over with soil.  The other option is to add the mixture to your worm farm, where the worms will further break down the waste into rich castings and worm tea for the garden.

Advantages over conventional composting

–       No odor – system can be used indoors in convenient location

–       Faster process – takes about 2 weeks to break down a full bin of organic waste

–       Can compost meat, fish and dairy – further reducing landfill waste from your kitchen

–       Does not attract rodents

–       Liquid extracted from mixture can be used as fertilizer in the garden

Disadvantages

–       More expensive – Most people purchase the liquid or powder form of bokashi mixture

–       More time required – Some people make up their own bokashi, which requires a little more time and effort to conventional composting

Building your own bokashi bin at home

Given that your average 20L dedicated bokashi bin costs over $60, an alternative option is to make your own.

Follow this step by step guide and in 30 minutes you will have your own ready to use bokashi bin.

Step 1

Purchase 2 X 20L (or larger if required) storage containers.  These can be any shape, as long as one fits inside the other and there is a gap at the bottom for the liquid to collect.  The storage conainters I used below cost $10 each

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Also purchase a simple drain tap with o-ring seal – this will need to be secured from both sides of the wall of the container to prevent leakage, so I used a simple threaded fitting on the inside of the container to hold the tap in place and keep the seal compressed.  The tap and fitting cost $6.

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Step 2

Drill a hole for your tap at the base of one of your containers.  The hole needs to be large enough for the thread to fit through, but no larger, otherwise the o-ring will not seal.  Ideally you would use a hole drill for this.  As I didn’t have a hole drill small enough, I used a 6mm drill and drilled mutiple holes taking care not to drill larger than the thread width on the tap.

Insert the tap through the hole and secure from the other side with the threaded fitting.  Note the o-ring seal is compressed against the outer wall of the container to prevent any liquid leakage.  Also the tap is positioned as low as possible to drain as much liquid as possible.

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Step 3

Drill out a number of holes in the base of the second container (without the tap).  This will act as the storage container for the waste and have the ability to drain all the liquid through to the outer container with the tap.  I used a 4mm drill hole and spaced the holes about 10mm apart.

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Step 4

Stack the container with holes in the base inside the container with the tap at the base and make sure the 2 containers are sealed wall to wall at the top and your done!  Just used one of the lids to seal the top container after adding the food scraps.

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The total system cost $26 and took around 30 minutes to put together.  This is a $40 saving over ready made systems available off the shelf.  You could also use cheaper buckets such as your standard white buckets with sealable lid saving a further $10.  I also purchased some bokashi mixture for $16 which is suppose to last an average household about 3 months.  I plan to make my own bokashi mixture in the coming months.

Here are some pics of the first of the food scraps in my system.  Note that you add a thin layer (2-3 tablespoons) of bokashi mix for every couple of inches of food scraps and compress the mixture down as much as possible after adding each layer (to keep the air out and aid in the fermenting process).

 

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Our system is stored in the laundry and should be full after about 2-3 weeks

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It will take a further 2-3 weeks of time to fully ferment the scraps, before they are ready to go into the garden.  Note that a good idea is to have 2 systems, so that you can allow enough time for the first system to mature before emptying out, whilst continuing to fill the second container.

So if you are concerned about the time to develop compost, attracting rodents, or the smell of composting, then the bokashi method may be the system for you!