Worm Leachate

My class made this worm bin back in March, and I’ve been faithfully adding food scraps, as well as carbon-rich material, every week or so. Worm bins are actually made with TWO bins, one nested in the other. The ‘top’ one has a bunch of holes drilled in the base, to let the leachate drain out, which collects in the ‘bottom’ bin. Today, I checked to see if there was any leachate, and found about a cupful of liquid! At this point, you might be wondering: What the heck is leachate???

“Leachate” is a umbrella term for any liquid that, while passing through matter, extracts soluble material. Leachate from a worm bin can be a mix of things, such as excess moisture (too many food scraps, not enough carbon) or worm urine. In a regular compost bin, this sort of thing soaks in to the ground below, but when composting in a worm bin, which are often used in concreted places such as a patio or porch, it is caught be the bottom bin. This liquid can be used in the garden as a fertilizer, but it’s hard to know what exactly the liquid contains. So to be safe, the liquid should be diluted 1:1 and experts recommend that you only use it on non-leafy vegetables or fruit trees.

After diluting the leachate, I decided to apply it to the Milpa/hugelkulture bed that is a riot of different plants. The squash leaves in this particular bed have been looking a bit yellow to me, which indicates that they could use some nitrogen (not a surprise, since hugelkulture beds are made using un-composted material which require nitrogen to break down, leaving little for the plants). We’ll see if adding this diluted leachate helps at all. I’ll give it a week, and if I see no improvement, I might give it a dose of fish fertilizer.

I’ve been quite happy with this bed overall. It’s super fun to watch what comes up, what dominates, what flowers, and what’s producing fruit. There have been a lot of buckwheat flowers, and right now there are a bunch of sunflower buds. The peas grew, but never bloomed. The beans are doing quite well, and there is corn too, though it is very short. The squashes are the true stars of this bed. I’ve already harvested summer squash here, but I see a ton of winter squashes beginning to fruit, too. Hopefully the leachate will help those to grow big and ripen beautifully!

Reader Question - Vermicomposting

A reader named Jen writes, “I am considering getting a vermicomposter, and the options range from high end to low cost: https://www.epicgardening.com/best-worm-composter/ The Worm Factory starts at $146 and others are more moderately priced, in the $100 range. The Hungry Bin is a whopping $346! Here are my questions: Should I invest in a more expensive worm bin and if so, why? Should I release some worms into my garden so that the birds have more to eat over the winter? Am I really doing anything about the impending doom of climate change by vermicomposting?”

Full disclosure, Jen is a close friend of mine from childhood. She lives in NC, in Chapel Hill, which is USDA Zone 7b. She lives in a forested area and has a lovely Japanese style garden, as well as some meadow plantings.

We all know the benefits of composting, so I don’t need to go through those again. Our awareness of food waste has been growing lately, and it’s good to figure out some sort of system for dealing with that (besides re-thinking your shopping and cooking habits, which I’ve had to do myself with our teenage son away at college). Chickens or pigs is ideal for this - nothing gets wasted if you have livestock to eat your leftovers. But worms are another livestock option that are ideal for those of us who don’t have the property allowance for larger animals.

I’ve used worms in various ways for years.

I’ve had an official worm bin, which was used by and then given to me by a neighbor, and it was an interesting experience.

These are usually a set of stacked bins. The top few have a perforated bottom, to let worms and leachate move between them, and the bottom one has a solid bottom to keep everything inside. There is also usually a spigot of some kind which allows you to drain off the leachate (basically worm pee). You then dilute this liquid and use it as a fertilizer. Additionally, the castings (poop) are removed periodically and added to your pots or beds.

I found this sort of system high-maintenance. It needs to be in an area that is protected from rain (there are openings in the top to allow air circulation); the top is easily removed by predators who eat all the worms (hence my putting rocks on top); you need to have a lot of leaves or newspaper or some other carbon source available to soak up all the nitrogen that is being produced (poop); and, when it’s time to empty the bins of worm castings, you have to somehow “sift” out the worms, which is supposed to happen naturally with the perforated bottoms but, in my experience, doesn’t work. I used it for about a year and then put it in the recycle bin (after removing all the worms and stuff and putting them in my regular compost).

I can see that this sort of system would be perfect for someone who doesn’t have any outdoor space - a balcony, or a garage, or even a laundry room could host a stack like this. But the mess you make when you remove the compost would make it less than ideal for indoor spaces. If you have very harsh winters, this system could also be good, but again, not easy to maintain indoors. Some people make their own worm bins which is far cheaper than buying something pre-made.

Something I have found far more sustainable is to have an enclosed outdoor compost bin of smaller stature, one made of natural materials that is open to the ground below. My dad made me one like this years ago, a two-compartment bin of old redwood decking, with a hinged lid and removable front panels. Because the bin is so small (3’x3’x3’), it doesn’t hold enough material to get hot enough to break down easily. My way around this is to buy worms every other year, and add them to the bin.

There is likely a worm farmer near you, wherever you live, where you can buy a couple of pounds of red wigglers for about $20 a pound (which you’ll need to do for a worm bin, as well). They will mate and produce more worms, but they also crawl out of the bin and into the surrounding garden, get eaten by birds, etc. So that’s why I buy them every couple of years. They really speed up the composting of my smaller bin.

I don’t bother to add any worms to the big compost pile that resides in the chicken run. First of all, they’d just get eaten by the chickens. Secondly, that pile breaks down faster anyway for many reasons - it’s bigger (more volume), it has its own dedicated sprinkler, and it gets turned by the chickens every single day. There are definitely worms in it - I see them every time I go to collect the finished stuff at the bottom - which have arrived from the surrounding garden.

And that brings me to something else you need to consider - there are already a ton of worms in your existing landscape. They are there even if the soil has been neglected for years. They reside deep inside the moist layers of soil. Rain brings them closer to the surface, as does organic matter. If you have a woodsy area, worms are part of the great soil ecosystem that breaks down all that organic matter - only a small part, to be sure, as bacteria and fungi do most of the work of decomposing the litter that lies on our soil surfaces. The very best way to ensure that you have an active and healthy soil ecosystem is to provide it plenty of organic matter. Don’t remove leaves. Add mulch to bare ground. And you may even want to bury your food scraps out in the landscape - just dig a hole next to a bush or a tree, put your scraps in, and cover them with soil. This is called “composting in place” and many people swear by it. There is a permaculture method called a “keyhole” planting bed, which is a raised bed shaped like a circle, with one path in to the center of the circle so you can reach everything. In that center, you place a wire basket (open to the bottom and the top). In that, you layer leaves and grass and food scraps, and it breaks down right into your bed.

I even had a horticulture professor who basically laid his food scraps down around his fruit trees, not even bothering to bury them! This looks unattractive but is effective. In my neighborhood that would attract even more nighttime creatures, so I need a more organized way to deal with scraps.

As for the birds, something like 98% of bird species feed insects to their young, even if they are seed eaters normally. The young need protein, and the best source of that is insects. Birds need a variety and abundance of insects, and so if you appreciate birds, the best thing you can do for them is to provide insects. Worms that live in the ground are good for some bird species, but worms that live on leaves are much better for a vast number of bird species. Worms that live on leaves, also called caterpillars, are usually a larval stage of many insects. So, as we’ve discussed before, there are many things you can do to increase insects in the garden: stop using pesticides; plant a variety of flowering trees, perennials, annuals, vegetables, and herbs; provide water in shallow dishes; and allow for different habitats - some mulched spaces, some bare dirt spaces, tree snags, piles of logs, etc. Be a slightly messy gardener! Don’t clean up too much. For more on this subject. you would do well to read “Bringing Nature Home” by Doug Tallamy.

And as for climate change and the state of our planet, any action we take as individuals can only help the situation, so I encourage you to compost in any way you can. If a worm bin is going to be the thing that gets you there, then do it. Individual actions allow us to feel as though we are part of the solution and give us hope, so they are important from a mental health standpoint as well. But we also need to realize that it’s going to take global action and policy to really shift the world towards a completely different thinking about climate change. I’m not saying that your individual actions don’t matter. They do. But as individuals, we really don’t have the power necessary to make a significant change. That’s why we need to be proactive about voting for people and policies that support making these big changes.

I hope this helps you to make a decision about whether or not to get a worm bin, Jen! Thank you so much for your question. I’ll be interested to see if anyone else has some other advice for you, perhaps a system that worked particularly well for them, or ideas for making your own bin.

It's Nice to Spend some Time in the Garden

I’ve been so inundated with homework this term. I’m taking some very mathy classes, which twists my brain and requires a lot of extra work for me to GET IT, DAMMIT, and also some very writey classes too, which is a lot easier for me but then has the sad side effect of not wanting to write anywhere else, including here. Honestly my brain is just completely full and kinda tired. I never worked this hard before in any of my college classes, which tells you a couple things: One, I failed a lot (truly, my first college experience was all about failing) and Two, if I wasn’t failing then it was a class that really interested me and so I was motivated to do well and it never felt like work. So, I’m learning what it is to be an ambitious college student and to be afraid of losing a perfect GPA, which I know, not such a big deal in the scheme of things, just - I’m having feelings and worries and anxieties.

Luckily there is the garden to which I can escape when I’m really overwhelmed. Some days, I just can’t get out there, and with the daylight slowly leaving us a bit at a time, the days are shorter too which doesn’t help. Today I made a list of things that I absolutely had to get done in the garden and I firmly stacked my books away from sight and headed out. Tom came with me which made it even more delightful. We had a big morning job which was turning the compost and sifting out whatever was finished, which turned out to be about 8 wheelbarrows-full, a wonderful result. But turning that big pile is a really big job, with long pokey things and big chunks of smelly wet things and just a huge mass of stuff to move and then to re-pile when the good stuff is taken from the bottom. The chickens absolutely LOVE it when we do this job, because the amount of bugs to be found is astronomical - the entire pile, literally, crawls with life. Since the birds are coming out of molt and need lots of protein to grow new feathers, this was a good time to expose all those creepies for them to gobble up. But having them running all over everything while you’re trying to move it… also a hassle. That’s ok. I was able to put a deep layer of compost under all the blueberries (they need a lot of low pH organic matter, and compost is acidic so it’s perfect), a deep layer under the apple tree, a deep layer around some ornamentals that really needed it, and to create two new beds for perennials and bulbs, which I’ve wanted to do for a while. One is under Adam’s window and is filled with plants his dear friend Sophie grew from cuttings and lots of bulbs, and the other is under our magnolia tree where I grow some natives but it needed some punch in the summer when the natives are dormant. I put a lot of bulbs there too. I splurged on a good amount of alliums and fritillarias. I also seeded a bunch of native poppies in those places.

just part of the haul

The winter garden is coming along marvelously. I’m always surprised how, when the soil is warm but the nights are cool, everything really germinates well. The shallots and garlic are already up, the snap peas are starting to bloom, and I’m surprised how big the broccoli plants are this early in the season. Very little needs doing in the veg beds, except that I need to sow a cover crop of red clover everywhere. I am just waiting until the veg crops have a good head start. The flower patches are all looking really wonderful, with six-foot tall (or taller) zinnias, cosmos, and tithonia. The bees and butterflies are still out during the sunny part of the day, but the lizards are starting to hibernate. Some birds have migrated back into the garden and it’s good to hear their songs again (the chickadees, the yellow-crowned sparrows). Leaves are starting to turn and drop and acorns are falling constantly from the Valley Oak, making very loud kerplunks when they hit the cars. It’s seems to be a bit of a mast year for them, while the galls are quite a bit fewer, at least it seems right now. Last year was a banner year for galls.

A friend from Idaho was visiting and said she’d already had snow, and I imagine many of you have already had your first hard frosts. We’ve got a while to wait for that. Meanwhile we’ve had some exciting, smaller earthquakes and some scary moments with wind and fire, but our October has been fairly quiet so far (knock on wood). Octobers are always interesting in California.

This afternoon is back to homework, but I’m glad I got to get out in the sunshine and use some muscles. What are you working on in your garden?

Corrections on my Biochar post

I had an email from Austin at All Power Labs this evening; I had made several mistakes in my post about biochar, and of course he would like to make sure the information is correct, and so would I! I don’t ever want to mislead my readers. So, I am going to copy his email in full here. He also sent me a lot of photos of before/after biochar, which I will share with you if you like (just contact me and I’ll send them on) - they are impressive (although I haven’t seen any results in my own garden yet and will report them when I do. I have to say my artichoke plants are just as big as the ones in the pictures, so … jury is still out for me on this. The proof will be in the pudding! The important part is that Gill Tract saw a huge difference in their garden).

Here is the email, and I want to say that I really appreciate a company that is 1) local, 2) taking something out of the waste stream and making it work for good, 3) invested in solving the climate problem, and 4) totally committed to their company and feel it’s important to make sure that the info is correct and not distorted. SO thank you very much to Austin for pointing out my mistakes and setting the record straight!

“(Austin wrote:) In this paragraph, the highlighted portion ought to be corrected:

(Elizabeth wrote:) So, here’s the scoop. All Power Labs was originally created to make renewable energy using biomass. That is, make power by burning the waste products of agriculture or even our urban yards - tree trimmings, wood chips, etc. In the process of making this renewable energy, a by-product was produced - bits of what looked like charcoal, very light and made of pure carbon. Originally they just threw this product out. Then they realized it was biochar, and high quality biochar at that, and that it was a coveted resource for farmers and gardeners, as it does a lot of cool things in the soil (which I will detail in a bit). The original purpose of the company, making renewable energy for use, was having trouble finding a niche in the very large solar and wind energy economy we have in California. So, they pivoted a little into the biochar side of things.

(Austin) The biochar is not pure carbon. It is about 70% organic carbon. (Organic carbon—in a from derived from an organism— as opposed to mineral carbon, such as in chalk. Chalk is calcium carbonate. Carbonate minerals contain CO2 in their crystal structures.) The remaining 30% is a mixture of ash, and residual oxygen and hydrogen. Our walnut shell biochar is about 15-16% ash.

Charcoal is the “fixed carbon” fraction of woody biomass. About 80% of the mass of a chunk of wood consists of volatiles, which come off as wood smoke. The volatiles contain about half of the carbon of the wood, along with most of the hydrogen and oxygen in wood. (Remember, wood is largely cellulose, which is a carbohydrate. That’s where the hydrogen and oxygen come from.) The remaining 20% of the mass is fixed carbon—the carbon that is left once all of the volatiles come off of the material. That’s where the other half of the carbon content resides. The fixed carbon remains, and if it goes through high temperatures, resists decomposition because the enzymes used by bacteria and fungi to break down most organic carbon compounds can’t decompose most of the structures that are produced by fire. The higher the temperature, the more resistant to decomposition pyrogenic carbon tends to be. This quality of resisting decomposition is called “recalcitrance”. It is not an absolute quality; lower temperature processed biochars have a larger fraction that eventually decomposes; the high temp processed stuff (like ours) has a very small fraction that eventually decomposes.

(Elizabeth) Now more about the process. Above is a photo of the “Powermass Gasifier” which is the machine that turns biomass into both energy and biochar.

(Austin) The name of the machine is the “Power Pallet.” It is a Biomass Gasifier genset.

I attached a process explanation for you to get a sense of how it works. (If anyone is interested in this - let me know and I’ll send it on to you - E)

(Elizabeth) Biochar doesn’t decompose. It’s already been processed into its permanent form - pure carbon. This happens in the process of Pyrolysis. The volatile carbon in the biomass is burned off (and used for energy), and what is left is like the embers of a campfire. Totally indestructible, permanent bits of carbon.

(Austin) This description, of being “indestructible, permanent bits of carbon” is more apt for diamonds or pure graphite. Biochar is not totally indestructible. Depending on how it is made, a certain fraction can very slowly decompose, but the bulk of it does not participate in the carbon cycle. The proportions depend on the temperature of processing. The proper way to state this is that the carbon content of charcoal does not revert to carbon dioxide without combustion. When charcoal is interred in the ground as biochar, it is essentially “reverse coal mining”—the production of concentrated black carbon and putting it in the ground.

Also, for pyrolysis, we have an explanatory page on our website that would explain it in the context of how we make biochar. If you would link this page, we would appreciate it:

http://www.allpowerlabs.com/gasification-explained

(Elizabeth) They have a very high CEC (cation-exchange capacity) which means that they add nutrient density to the soil.

(Austin) CEC doesn’t add nutrient density, but it does add the ability to store nutrients. It is more like nutrient storage capacity. The key thing is that water soluble cation nutrients don’t just dissolve into water and leach out; the CEC sites act like velcro and cling on to water soluble cation nutrients, but hold them loosely enough that plants can get them off as they need them. High CEC soils can store a massive amount of nutrients without burning plant roots because the nutrients are not all dissolved in the water at once.

(Elizabeth) I also really appreciate that the biomass used to make this biochar is nut hulls from California orchards. This is taking something out of the waste stream, something that takes hundreds of years to decompose, and putting it to good use.

(Austin) The nut shells don’t take hundreds of years to decompose. Depending on how they’re disposed of, within a few years, all the carbon content in them is back in the atmosphere. This is sort of like how wood chips and nut shell mulch disappears like compost. ”

— Austin Liu, sales engineer, All Power Labs

Let me just say again: I totally appreciate these corrections. I want to learn, too!

Learning about Biochar

A couple of Tuesdays ago, I gave a talk at the Merritt College Horticulture Department, in their Design Forum. The talk was centered around how to create an urban farm in a typical residential yard, as we have done here. It was a great night, filled with interesting questions from the audience, and as usual, I not only doled out some learnin’, I also received some learnin’. Every conversation I have with gardeners or farmers leaves me with new impressions and new knowledge, and then, of course, new questions.

One audience member asked me if I had any experience with biochar. The short answer was no. The slightly more detailed answer is that I’ve done some reading about it, and watched some educational videos from Living Web Farms about how to make it and apply it to your garden. I’ve also heard some negative things about it - that it’s a hoax - and I also have had some reservations about the way it is made; I have worried that the process of creating the biochar is actually releasing a lot of carbon into the atmosphere. The student who asked the question showed me some pictures from her own garden, of plants grown side by side, with and without biochar. Looking at those pictures, it was clear that there was a difference in the size, health, and production of the plants that grew WITH biochar. This intrigued me and I wanted to source some biochar of my own to try.

As my friend Lawrence likes to say, serendipity is everywhere, and that same night I happened to pick up a free copy of the fall edition of Edible East Bay magazine (which they make available in the Hort Dept), which I always enjoy and learn a lot from. And wouldn’t you know it, there inside was a huge article about biochar, and a story about a company that makes it in Berkeley (All Power Labs, more on them in a minute) and a community farm, Gill Tract, that has been trialing the biochar in their compost and raised beds systems. Well. I immediately contacted the lab and signed up for a year’s subscription of biochar. Today I went to pick up the first batch, and was absolutely blown away by the welcome I received from Aidin at All Power Labs, who then spent a good deal of time showing me around the joint and explaining the process of how biochar is made. He also welcomed me to the Local Carbon Network, which is a “community-powered local drawdown network.” I love this and I love that I’m a part of it, officially, though honestly I’ve been a part of it for years. :)

At the end of my visit, I mentioned Merritt and said that the Hort Dept should do some trials of their own with this product, and Aidin said, “What a coincidence, my coworker Austin is giving a presentation at noon at Merritt,” which turned out to be in my friend Lawrence’s permaculture class! I texted Lawrence and asked if I could drop in and hear the lecture and he kindly allowed me to do that, and I got to hear the details all over again (and take notes this time) which really helped cement the ideas in my brain. More serendipity!

So, here’s the scoop. All Power Labs was originally created to make renewable energy using biomass. That is, make power by burning the waste products of agriculture or even our urban yards - tree trimmings, wood chips, etc. In the process of making this renewable energy, a by-product was produced - bits of what looked like charcoal, very light and made of pure carbon. Originally they just threw this product out. Then they realized it was biochar, and high quality biochar at that, and that it was a coveted resource for farmers and gardeners, as it does a lot of cool things in the soil (which I will detail in a bit). The original purpose of the company, making renewable energy for use, was having trouble finding a niche in the very large solar and wind energy economy we have in California. So, they pivoted a little into the biochar side of things.

Shortly after that, they partnered with Gill Tract farms to do some trials and figure out how this stuff really works. Bob Flasher at the farm has been working closely with APL and seems to be quite sold on how the char performs in his garden and has documented how the plants perform. Knowing that he has been an early adopter of the char helps me to feel good about moving forward, trying it in my own yard.

Now more about the process. Above is a photo of the “Powermass Gasifier” which is the machine that turns biomass into both energy and biochar. The energy now is used to run the machine, so it’s a closed loop - no emissions or volatiles are escaping into the atmosphere. In fact, the carbon that is trapped in the biomass is turned into a product which can help sequester carbon into the soil. At this point, you might be saying, “Well, doesn’t compost do that too?” and the answer is yes, it does. It helps feed the microbiology which are turning the compost into humic acids in the soil, which do sequester carbon. There are some problems with compost, though, which you might have experienced (I know I have). One, it doesn’t last more than a season. I put a couple inches on my beds each fall, and by early summer, the beds look like they never had it. The soil surface is quite low, several inches below the top of the wooden beds. What happened to the compost? Well, some was turned into nutrients for the plants by the microbiology in the soil. Some, however, was off-gassed, releasing carbon into the air again as it decomposes further. Compost does continue to decompose, it doesn’t stop just because you’ve moved it to your veg beds.

walnut hulls, an abundant waste product from California orchards, which will be turned into biochar

Biochar doesn’t decompose. It’s already been processed into its permanent form - pure carbon. This happens in the process of Pyrolysis. The volatile carbon in the biomass is burned off (and used for energy), and what is left is like the embers of a campfire. Totally indestructible, permanent bits of carbon.

These bits of carbon, if applied to a garden/farming system, become hosts for a ton of microbial life. They absorb humic material. They have a very high CEC (cation-exchange capacity) which means that they add nutrient density to the soil. It improves drainage (tilth) while helping with water retention, as they can absorb many times their size in water. They improve friability of soil. They store the mineral nutrients from biological processes. They even, apparently, bind heavy metals and immobilize pollutants.

These are the composter tumblers that they are using at All Power Labs to do their own trials with biochar. And Aidin was clear that they recommend that we compost biochar first, not just add it directly to planting beds. There the biochar will be inoculated with the microbia of the compost pile and start to do work. There is a lot of evidence from Gill Tract Farm that adding biochar also increases the temperature of compost piles by quite a lot (this is something I desperately need). Not only that, Gill Tract has seen the temperature spike and then remain at high temperatures for six weeks after an application of biochar! I’m hoping to see this in my own compost piles. I came home with a large bucket of char, and added only a cup to the worm bin and about 10 cups to the large compost pile in the chicken run (they recommend adding 10% biochar by volume, an estimate is ok. My bucket should last three months). We’ll see how that works to activate heat and decomposition.

I also really appreciate that the biomass used to make this biochar is nut hulls from California orchards. This is taking something out of the waste stream, something that takes hundreds of years to decompose, and putting it to good use.

If you’re interested in your own subscription of biochar and live in the area, you can contact Aidin at The Local Carbon Network. It’s not cheap, I’ll warn you now, but I imagine that in time, when the benefits of biochar are documented and realized, the price will level out. I also believe it is worth it, if it will help me process enough compost to add two inches to all of my planting beds once a year. This would be terrific because I’m tired of buying compost, for many reasons: price (a lot more than this biochar), the unknown ingredients and their provenance, and the work/energy to get it here. So I’m invested in trying it to see if I can start to produce more compost here, in my yard.

To learn more about biochar, another good resource is the book Kiss the Ground , which is also, I believe, a movement that is part of the Marin Carbon Project.

The back of All Power Labs, which I just love. So Berkeley!

Have you tried making or using biochar? If so, I’d like to hear about it!