fermented compost - diy style

In the last post, we took a quick look at worm nests, what they are and how they are a critical function of the fermented compost method.  As promised at the foot of that post, this time we're going to look at how to get your own DIY fermented compost system together.

I'll state here that fermented compost is more or less the same as Bokashi Kitchen Composting.  I say more or less, because there are a few minor differences - Bokashi is a proprietary system, developed in Japan, which utilizes a specially designed Bokashi composting bucket, which you can see here:

bokashi kitchen composting caddy

you'll note it has a tapering design, with a lid on top and a tap underneath, from which you collect the juice from the decomposing food waste placed inside.  Inside the Bokashi bucket, you have a filter and it comes with a scoop and a plastic "tamper" for squishing down the food waste:

inside the bokashi kitchen caddy

Bokashi is a Japanese word, meaning "fermented organic matter" and is a system of trench composting method used on "ultra organic" farms, as part of the Kyusei Nature Farming movement - monks who believe in using permaculture based farming practices as a spiritual path to connect with nature's rhythms.  In the original Bokashi system, rice bran is fermented with microbes, is dried out, then mixed with vegetable waste, animal manure and liquid microbe brews and then layered up in the trench, to convert to humus under the soil.  It's similar in many ways to Rudolf Steiner's various preparations, familiar to those who practice Bio-Dynamic Farming.

classic bokashi making

In the 1990's Dr Higa of Ryukyus Univeristy in Okinawa decided to make his own commercial microbe brew and wanted to adapt the Bokashi system for the kitchen - to encourage urban dwellers to engage in this organic system for building healthy, humic soil and so the Bokashi Kitchen Composting system was born. All well and good, but there are a few flaws in the system which can mean the difference between well made and healthy fermented compost and a black, sloppy and potentially pathogenic problem. It seems not all the stages of making fermented compost have translated too well, so here we go back to basics and we look at a DIY method, without the need to buy in to the commercial system.

First, you have to understand that the key to making the best kind of fermented compost is to make sure the system is air-tight, being an anaerobic (without air) process.  Like a stomach, we need to make a chamber which keeps out air, to allow the anaerobic microbes to ferment the food waste, but which allows any liquid to percolate through the microbe-rich bran (we use wheat bran, not rice bran) and collect separately.

For this, we need two empty and air-tight containers, one to fit snugly inside the other, like this:

one fits snug inside the other - an airtight seal

You can see that when they're placed one inside the other, there's a gap at the bottom, between the two containers.  This is where the juice will collect.  In this pic, i'm using two popcorn buckets for demonstration only - you won't fit much food waste in a bucket this size.  If you don't generate much food waste something this size will do you fine, but for a larger family, a larger twin bucket system will be needed, though the principle stays the same:

how it all fits together

This is the bucket system we made and you can see there's already some food waste in the top bucket and some juice collecting in the gap, as previously described.  So how does the juice get into the gap? Well, for that, you need to either drill holes in the base of the top bucket/container, or use a heated metal skewer (usual health and safety caveats apply here - in short, use some common sense):

drilling holes in the top bucket

Once your kitchen bucket system is ready, you need some microbe-laden bran, or BUGS bran as i call my own bran which i make for our family and friends.  Speak to your local council for a supply, check out ebay for Bokashi Bran, but be aware - some commercial producers of the bran don't put much in the way of microbes in the bran they sell and that can mean little to no fermentation takes place, which can mean problems arise.  The bran you get should smell strongly of salt and vinegar crisps, crossed with wheatabix - if it doesn't, it's likely that the bran producer is skimping on the supply of microbes to the mix.

Phase 1

Once you have your container/bin, sprinkle a layer of BUGS bran over the bottom. Don’t worry if some bran falls through the holes to the lower container.

Layer up all food waste.  This can be cooked or uncooked food, diary, citrus, bread, meats, teabags, coffee grinds, etc.  Remember to chop larger items, e.g. cauliflower stems, banana skins. A pair of scissors is a handy tool for this:

chopping waste to create a better fermentation action

Push the food waste down firmly to allow any liquid to drip through the holes in the bottom.  We recommend using a potato masher.  The objective is to push any air out of the waste and force excess liquid through the holes to the bottom gap:

mashing down = no air gaps

Sprinkle over BUGS bran to cover the surface of the waste and seal the container:

covering with BUGS bran

Repeat layering food and bran until the container is full.  Don’t forget to get as much air out as possibly by applying firm pressure.  You should keep your bucket assembly in the kitchen, where it's most convenient to get to:

stores tidily away

Phase 2

Once the container is full, it will need to be left to ferment for a minimum of two weeks.  But before storage, the liquid must be removed.  Lift out the inner container and pour the liquid into you compost bin or down the drain.  Putting this down the drain in summer can help keep your drains unblocked.

draining the liquid

During the process of compiling the waste the liquid from the decaying food will percolate through the bran, waking up the dormant microbes, which will begin to ferment the food waste. A layer of brown liquid will have collected in the gap between the containers.  On top of the liquid you may see white lumps floating – this is a product of the casein forming bacteria, which indicates the fermentation process is underway.

products of good fermentation

Once you've drained off the liquid from the bottom container, put the assembly back together and store out of direct sunlight for two to three weeks minimum to allow full fermentation.

storing outside to ferment

Whilst the full bucket assembly is fermenting for two weeks, you'll need another assembly of two buckets, prepared in the same way, to continue to collect your kitchen food waste.  Instead, you can do what we do and transfer the contents of your food waste into a larger sealable container, which you can then store for longer:

transferring to a larger container

As you can see, I have three larger containers, all full with fermented compost.  these larger containers I managed to blag obtain from a local company, who were throwing them out.  The benefit of transferring to a larger container is that you can store the fermented compost for months until you want to move on to the next stage.

If you've transferred your fermented waste to a larger container, you'll now need to wash out your kitchen bucket assembly with fresh tap water- I simply use a garden hose (and no soaps or detergents).

washing out your bucket system

and then add a layer of bran over the holes in the (cleaned) top bucket again, ready to go back in the kitchen:

getting ready to go again

Phase 3

After the fermentation phase is complete, dig a trench approximately 10” – 18” deep and spread the fermented compost across the base of this trench. 

digging a trench for your fermented compost

The compost will still look as it did when first added to the process, albeit slightly browner. Backfill the trench with soil and you're done! (remember to clean down your buckets of course - see above)

back-filling with topsoil

Leave in the ground for 8 – 13 weeks (depending on soil temperature / time of year).

Halfway through the 8 week in-soil phase, feel free to get a spade and go investigate - you should now see your very own worm nests!

worm nest!

Once the compost has been in the ground for the minimum required time, dig over the soil where the compost was buried and see the soil quality for yourself.

Over time, the soil will build into a rich, humic and highly nutritious growing medium - able to retain moisture, feed plants luxuriously and become a home to many healthy earthworms. 

worm nests, fermented compost and building highly humic soil

If you saw the last post "microbes in the community" you'll note we had a lot of interest in our pics of worm nests, of which i promised to explain a little more...

"worm nests?" i hear you ask "but worms don't make nests, do they?"

well, maybe they don't, but when a young child sees the likes of this:

 then you have to ask yourself what else you'd call it!

Of course, this is all part of a process and that process we call "fermented compost".  Why fermented compost?  Simply put, we take our (highly nitrogenous) kitchen waste and ferment it with microbes, before adding it to the soil, for the worms to munch away at.

Compost worms (Eisenia fetida) are different than earth worms, firstly. They are commonly known as redworm, brandling worm, tiger worm and red wiggler worm, but are a species of earthworm adapted to decaying organic material. When roughly handled, an eisenia fetida exudes a pungent liquid, thus the specific name foetida meaning foul-smelling. This is presumably an antipredator adaptation.

 Although very simple organisms, worms can be thought of as "cows of the soil" in that they require bacteria in their guts, in order to process the organic matter they consume (along with a grit-like calcium carbonate substance they produce through internal glands).  In studies of soil the world over, scientists have found that where there is a lack of soil bacteria, worms populations are sparse.  Conversely, where healthy worms populations exist, the soil bacteria is plentiful and healthy.  This explains, in part, why fermented compost is so attractive to these little soil-recyclers and why, in a bacteria-rich resource such as fermented compost, they find their way in, eat plentifully, colonise, reproduce and turn the fermented compost into a nursery, replete with cocoons (worm eggs) and white baby worms, as you can see from the pic of the worm nest above.

To give an idea of scale, here are some pictures which zoom in from the spade level, to the close-up, where a 50 pence piece is shown.

As a point of note, that white substance you can see near the 50p is a product of fermentation, specifically a casein (cheese-like) material which is produced by Lactic Acid Bacteria - the very same lactic acid bacteria responsible for preserving Wooly Mammoths in the permafrost regions of Northern Europe.  For an elegant visual explanation of how Wooly Mammoths get preserved, be sure to check out the National Geographic Article here.

As you can see in the above pics, the white baby worms are plentiful.  Human hair gives an idea of the scales involved - you can even make out the tiny worm eggs (cocoons) and how the soil particles are sticking together, thanks to the humic content of their casts.

These photos were taken about 4 weeks after burying the fermented compost in a trench in the soil - half way through the 8 week process (in warmer weather - in colder weather it takes from 10 - 13 weeks for the fermented compost to be fully consumed by the worms).  You can think of these compost worms as a pioneer species, because after the compost worms have done their work, earthworms come in to colonise the now organically rich soil.

Indeed, as these later pics show, the baby worms soon become healthy adult worms, to continue the process:

Benefits of Humus

• Humus can hold the equivalent of 80 to 90 percent of its weight in water, so soil rich in humus is more drought-resistant.

• Humus is light and fluffy, allowing air to circulate easily, and making soil easy to work.

• The sticky gum secreted by microbes while forming humus hold soil particles together in a desirable crumb structure.

• Humus is extremely effective at holding mineral nutrients from being washed away in rain or irrigation water, and in a form readily available to plants. Ample reserves of humus also provide additional plant nutrients in times of need.

• Humus is able, because of its biochemical structure, to moderate excessive acid or alkaline conditions in the soil-a quality known as buffering.

• Many toxic heavy metals can be immobilized by soil humus, and prevented from becoming available to plants or other soil organisms.

• Although the color of humus can vary, it is usually a dark brown or black color, which helps warm up cold soils quickly in the spring.

In the next blog post, i'll show you how to make your own fermented compost system, so you too can start to make your own worm nests!

microbes in the community

"summer's here and the time is right, for..." ...dancing in the streets 

attending garden parties and hearing all about microbes?

Ok, so that may never take off as a remake of the famous Motown hit, but nonetheless, this weekend saw a raft of garden parties, fêtes, school fayres and the like, full of festive folks enjoying the wonderful English summer, whilst supporting local good causes.

On Saturday and Sunday, the sun was shining brightly, the summer breeze was wafting gently and the stall at our local Old Town Festival event was well attended, with visitors eager to see what BUGS was all about, smell the difference between the untreated bran and the microbe-rich BUGS bran (which most people agreed smells like really strong salt and vinegar crisps, crossed with wheatabix!). The pictures of worm nests drew particular interest, yet although most people claimed to be squeamish, not one turned the page to avoid the close-up pictures but instead bent forward, looked more closely and asked all sorts of intelligent and interesting questions about what it was they were looking at. (more to follow on that subject, over the next few blog posts, given it proved so popular)

We gave away samples of microbe brews, for those interested to try for themselves, we spoke about peak oil and what this would mean for food growing in the future (if we can't afford the rising cost of synthetic Nitrogen, how exactly are we going to feed ourselves?) as well as the even more troubling concept of peak phosphor, given that whilst Nitrogen at least can be synthesized, phosphor can't be.

All in all, visitors to the stall were interested, engaged and wanted to know more, even though not all those attending grew organically. Hopefully we gave those we saw something new to think about and encouraged some to think about what they might do to start growing food for themselves, organically (and with the help of beneficial microbes).

At various points during the afternoon, those attending the garden fête gathered around to hear a variety of speakers give presentations, which the organisers had arranged. Nobody had expected a talk all about "the fascinating world of micro-organisms" but there it was - like a living example of the nerd in the yakult advert (you know the one - that poor nerdy chap who talks endlessly about bacteria and who pretty girls avoid at all the hippest parties) waxing lyrical about the role of beneficial microbes and what they can do for plant and human well-being.

Contrary to expectations, the talk went down rather well (who'd have thunk!) with many listeners making a bee-line for the stall to learn more and see what it was all about in greater detail.  One illustrative graphic was employed, showing the scale of the microbial world under discussion.  In fact, the graphic (see below) set the scene in describing the otherwise hidden world, bringing it to the light of day and into the focus of attention.

So when otherwise trivial facts emerged from the talk, such as the fact that, in a typical teaspoon of garden soil, there are approximately 5,000,000 bacteria - it became a figure not entirely meaningless, but an illustration of just how diverse and biologically active this hidden world beneath our feet really is.

Other fascinating facts, such as the mind-boggling statement that over 90% of the cells in our bodies are actually bacteria, carried real weight. Here in this blog (and in the "about this blog" page), we've referred to the fact that as a society we've been conditioned to think of bacteria as products purely of disease, of illness and of harm.  Now, taking the above graphic into consideration and coupled with that 90% bacteria by volume factoid, do you still think it's all about disease?  Hopefully not... and hopefully the door is opening on seeing bacteria as a natural part of who we are and what we are, as creatures who are partners to an invisible army of allies.

The soil food web is a subject we've yet to cover in depth in this blog, but as is the case with the above 90% of our bodily system factoid, so is the case within the soil - bacteria (and other microbes) form the foundation for an entire mini-ecosystem of partnership, of beneficial biological action that unbeknown to us humans at our scale, nevertheless benefits us in ways we simply can't perceive - or at least not without the help of tools such as powerful microscopes.

So, in summary, the sun shone, the breeze wafted gently and in one small corner of traditional English culture, science, tea and home-made cakes mixed to create an eclectic diversion for those in attendance.

capturing carbon in the soil - chelation in action?

Discover Magazine ran an interesting article the other day, following studies at Ohio State University to look at how much Carbon Dioxide soil might soak up.  Claims that the agricultural soils of the world have the potential to soak up 13 percent of the carbon dioxide in the atmosphere today—the equivalent of scrubbing every ounce of CO2 released into the atmosphere since 1980- may be bold, but research suggests that biologically rich and diverse soil may be able to help current concerns.

Rattan Lal first came to the idea of soil as a powerful carbon sink (pdf) not through an interest in climate change, but rather out of concern for the land itself and the people who depend on its productivity. While carbon-depleted soils tend to be dry and prone to erosion, carbon-rich soil is dark, crumbly, fertile, and moist. In the 1970s and 1980s, Lal was studying soils in Africa so devoid of organic matter that the ground had become like hardened cement. There he met Roger Ravelle, a pioneer in the study of global warming. When Lal made a despairing remark about the impoverished soil, Ravelle suggested that the carbon had moved into the atmosphere. “I told Roger I didn’t know where it had gone; I just wanted to put it back,” Lal recalls.

Ravelle was right. For millions of years, a natural partnership between plants and soil microbes has helped regulate carbon dioxide levels in the atmosphere. During photosynthesis, plants absorb carbon dioxide from the air and transform it into sugars and other carbon-based molecules. Some of those carbon products transfer from the roots to symbiotic fungi and soil microbes, which store the carbon in the soil as humus.

The invention of agriculture some 10,000 years ago disrupted these ancient soil-building processes. When humans started draining and plowing up the natural topsoil for planting, they exposed the buried carbon to oxygen, creating carbon dioxide and releasing it into the air. Animal husbandry made things worse, as domesticated animals began grazing grasslands down to the earth. In places where the ground is bare—from overgrazing or from the common practice of leaving fields unplanted for part of the year—photosynthesis stops, and so does the storage of carbon in the soil. Lal calculates that land-use changes such as these have stripped 70 billion to 100 billion tons of carbon from the world’s soils and pumped it into the earth’s atmosphere, oceans, and lakes since the dawn of agriculture. Today agriculture and other land-use changes account for about a third of global greenhouse gas emissions.

To quantify soil’s carbon sequestration potential on agricultural lands, soil scientist Whendee Silver of the University of California, Berkeley, is conducting a first-of-its-kind study on a 539-acre cattle ranch near Nicasio, California. In a collaboration with ranchers and local and state land management organizations called the Marin Carbon Project, she and her students are testing the effects of compost created from city yard waste (such as leaves, branches, and lawn trimmings) and agricultural waste (including manure and cornstalks) on carbon storage.

Although previous experiments have shown that compost increases soil carbon, Silver is among the first to examine whether real-world ranchers can use it effectively to enrich the soil on their rangeland. She has already found a large increase in soil carbon two years after a single application of compost, probably due to enhanced vegetation growth. On the basis of her results, Silver projects that 28 million acres of grazing land in California could absorb 42 million tons of carbon dioxide—nearly 40 percent of what the state’s electrical power plants produce in a year. To accomplish that, each acre of land must absorb just 1.5 additional tons of carbon dioxide. “Given what we’ve seen in our experiments,” Silver says, “one and a half tons is doable.”

In Australia, Christine Jones, soil ecologist emerita of the New South Wales Department of Land and Water Conservation, is testing another promising soil-
enrichment strategy, one that relies on perennial grasses. Since carbon sequestration stops in the absence of living plants, Jones and 12 ranchers in Western Australia are working to build up soil carbon by cultivating grasses that stay green year-round. 

Like composting, the approach has already been proved experimentally; Jones now hopes to show that it can be applied on working ranches and that the resulting carbon capture can be accurately measured. Over the course of four years, she has charted the carbon content of the grasslands, and when the first phase of the project concludes this August, philanthropist Rhonda 
Willson will pay the ranchers for every additional ton of carbon tucked away in their soils. 
“The changes we’ve registered over the past few years will surprise the world,” Jones says.

Silver and Jones hope that projects such as theirs will demonstrate the role that farmers, 
ranchers, and other land managers can play in mitigating the effects of heat-trapping greenhouse gases. Lal says that the greatest opportunities lie in the world’s most depleted and eroded soils, in sub-Saharan Africa, south and central Asia, and Central America. Success there will rely on providing farmers the tools and knowledge to improve their land, as well as financial compensation for their carbon enrichment of the soil.

The same is true in wealthier societies like the United States, where most farming operations chase productivity through large applications of fertilizer. Changing long-standing habits will require a system that rewards land 
managers not just for the corn or beef they produce, but also for the carbon they can build into their property. “Farmers should get compensated for protecting the ecosystem,” Lal says. “This is something worth paying for.”

Regenerative 
 Agriculture 
 An approach that aims to protect natural resources such as soil through techniques including crop diversity and rotation.

Carbon Sink 
A reservoir that can hold carbon and prevent it from escaping into the atmosphere. Proper management could turn agricultural soils into a powerful sink.

Marin Carbon Project A joint effort by scientists and ranchers in California to study rangeland’s potential to soak up carbon.


Compost 
Fertilizer made of decaying organic matter. By boosting plant growth, compost helps to increase soil carbon storage.

Perennial Grass 
 According to an ongoing study in Australia, planting ranch lands with grasses that remain alive year-round also increases the amount of carbon trapped in the land.