Bokashi is a fantastic indoor “composting” method with a wide range of benefits, including the following:
- It doesn’t take up much room.
- It won’t be overrun by pests.
- There is less chance of foul odours.
- It’s very easy and fast!
- It can handle a wider range of wastes than typical composting.
But the one big caveat is that you don’t actually end up with a finished compost since it is technically an anaerobic fermentation process. This can be especially inconvenient for the cold weather warriors who want to keep on processing their wastes all winter long!
In our Bokashi - Phase II article, we outlined ways to get bokashi “precompost” ready for regular (aerobic) composting. One method we briefly touched on - likely the one with the most potential to be helpful during the winter months - is known as the “Soil Factory” method.
In this article we will flesh out this topic in more detail, and share how we like to put our own unique PC spin on the process!
Soil Factory Basics
The Soil Factory (SF) method is a strategy designed to help you get bokashi precompost ready for your garden, or (aerobic) composting systems, in 2-4 weeks. Most people suggest mixing actual garden soil with your precompost - usually at a ratio of ⅔ soil to ⅓ precompost - but if you don’t have garden soil, some other good options include:
- Bagged organic potting soil
- Old soil from potted plants.
- Good quality compost.
- Well-aged livestock manure.
- Leaf mold
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Our own (PC) Soil Factory approach involves a “3-Zone” set-up that’s actually quite similar to that of our DIY Worm Bin (minus the composting worms, of course). There’s a false bottom, a main Soil Factory (waste-break-down) zone, and a cover zone.
The key with the SF method is to provide the anaerobic precompost with the opportunity to break down, aerobically, in a microbe-loaded environment.
In place of actual soil, we prefer to use different bedding and living materials - but whatever materials you choose to work with, it’s important to make sure they will: 1) provide C:N balance for the rich bokashi wastes, 2) soak up excess liquids, 3) create air spaces, and 4) ensure that plenty of aerobic microbes end up where they need to be!
Supplies Needed:
- A plastic tub and drill for holes.
- Carbon-rich bedding. Ideally a mix of 2 or 3 different types, including both absorbent and bulky materials.
- Some form of living material or soil (refer back to the list shared earlier for different possibilities).
- Finished bokashi precompost.
Step #1 - Choosing/Preparing Your Tub
This can also be quite similar to the process of starting up a DIY plastic worm bin. We recommend a good quality tote (HDX bins are our favourite) in the 40-70 litre range.
You can drill 20-30 holes in the lid, and 10-20 in the upper sides to help ensure the system is well-oxygenated. Remember, we’re trying to transition our precompost from anaerobic fermentation over to aerobic composting - so, as long as you can maintain a moist environment during the process, there is really no such thing as “too much aeration”. 😀
NOTE: you can also drill holes in the bottom of a SF bin for drainage but this isn’t mandatory (as long as moisture is balanced properly). If you do go this route indoors, make sure you have some form of catch tray sitting underneath. Outdoors, it’s totally fine to let the system free-drain into the soil, but if the bin is sitting on a hard surface - such as a patio or concrete pad - we recommend not using drainage holes.
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Step #2 - Drain Excess Bokashi Liquid
Even with fairly regular leachate drainage during the bokashi fermentation process, you can still end up with a very wet precompost. We recommend one last pressing out using a potato masher to help release as much additional liquid as possible.
The leachate can then be drained from the reservoir and used in a variety of ways, including pouring it down your drains or into your toilet, where it can help to break down calcium deposits and provide other benefits.
NOTE: you could technically add the liquid to your Soil Factory, but you will need even more dry, absorbent bedding to soak it all up (your goal should be no liquid pooling in the bottom of the SF bin).
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Step #3 - Set up Your Soil Factory
Again, there are two main options for getting your Soil Factory started: 1) you can use the more traditional approach, mixing some form of soil/compost with your bokashi precompost (⅔ soil and ⅓ precompost should work well), or 2) you can use our 3-Zone approach.
The advantage of the 3-Zone approach is that it virtually guarantees that you are going to end up with excellent moisture-management, airflow, and microbial inoculation. This can result in a faster breakdown/stabilization process.
A perk with the more traditional approach is that it is easier/faster to get set up - and to be clear, it is still effective (especially if you leave it to sit for longer).
It’s important to mention that our 3-Zone ratios will be somewhat different for a Soil Factory than for a DIY Worm Bin. Instead of ⅛, ¾, ⅛, you should aim for ¼ false bottom, ½ SF zone, ¼ cover zone. This helps to ensure that your SF ends up with plenty of stable material (and air space) to help the process along.
Also unlike the DIY worm bin 3-Zone approach, the volume of your different zones in a Soil Factory will be dependent on the volume of precompost you have to work with, not the volume of your bin, so don’t be surprised if you end up with plenty of empty space (especially with larger bins) - this is totally fine.
For your false bottom, corrugated cardboard is a great option - and one that’s readily available for most people. We use a larger-capacity paper shredder to get ours “bin-ready”, but even basic hand-ripping is great for this zone (and remember, it should be added dry).
Making Your Soil Factory Zone Mix
Empty your precompost into a plastic mortar tray or some other tub.
Start mixing in your bedding/living materials/soil to the point where all materials are integrated really well and the mix has soaked up most of the moisture. It’s OK for it to be somewhat wet since the dry false bottom and cover materials will help to balance it out - but there shouldn’t be much in the way of liquid pooling in the bottom.
NOTE: Mixing in some form of rock dust mix - like our pH Buffer/Grit - can be a great way to also balance out the acidity of your precompost, but it isn’t mandatory.
Your cover zone can be similar - even identical - to your false bottom. It’s really just there to help with moisture-management and to ensure that you end up with a nice, stable mix once the process is complete.
We have a wide range of materials available here on the farm, so we opted for a shredded cardboard / living material combo for our cover zone (you can never have too many beneficial, aerobic microbes). Again, working with materials that are both effective and readily available is usually the best way to go!
Once all your materials have been added, pop on your lid and away you go!
Just so you know, while you’re more than welcome to check on things during the 2-4 week break-down period, it’s definitely not critical if the system has been set up properly.
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Step #4 Putting Your SF “Soil” To Good Use!
OK, so the material you end up with in a Soil Factory isn’t really “soil”, but it can be pretty amazing stuff nevertheless - especially if you follow the guidelines outlined in this article!
If you do happen to have your Soil Factory going at a time of year when you still have good access to outdoor gardens and composting systems, don’t hesitate to start using the material once the 2-4 week period is complete.
You will know it’s “ready” based on how it looks and smells. If it seems quite a bit more broken down (than the precompost), with a nice earthy smell - it’s definitely ready for use. If, on the other hand, there’s still a fair bit of “pickle-y” bokashi smell, and it doesn’t seem to have broken down all that much, just leave it to sit for longer.
NOTE: Various factors, including temperature (big one), can have a major effect on the speed of the process!
It’s also worth keeping in mind that, just generally, there is no rush to put your Soil Factory material to use. In fact, if anything - like a fine wine - it’s probably only going to get better with age! 😀
Partnering with Worm Composting
If you happen to have an indoor worm bin up and running at the same time as your bokashi bucket, the good news is that this can be the perfect place to deposit your Soil Factory outputs. After your 2-4 week aging period - even if the SF mix doesn’t seem completely finished - feel free to start adding modest amounts of it to your worm bin and see what the worms think.
Unlike bokashi precompost straight out of the bucket, SF material will likely have a rich population of aerobic microbes, and much smaller quantities of potentially harmful acids and alcohols, so there’s a good chance your worms will move into it quickly!
Final Thoughts
If you love the idea of processing your kitchen scraps all winter long using a bokashi bucket, but you’re not really sure what to do with the finished precompost, the Soil Factory method offers an excellent way to get those materials garden/compost ready, and to free up your bokashi bucket for more use!
Testing this out for yourself? Be sure to drop us a line and let us know how it turns out!
Helpful Related Articles
What is the Best Way to Deal with Holiday Meal Wastes?
Bokashi - A Simple, Effective Method for Beneficial Kitchen Waste Conversion!
Bokashi Gone Wrong
Bokashi - Phase II: Turning Your precompost Into Beautiful Black Gold!
How to Feed Your Worms to Get The Best Results From Your Worm Bin
Smelly Worm Bins - Possible Causes & Effective Solutions
What Is “Living Material”?
Bedding - The Most Important Material in Your Worm Bin?
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