Beautiful, Recalcitrant Biochar

Have you heard of Terra Preta yet?

The Amazon Rainforest does not have good soil. Rainforests don’t. But there are several large pockets of magnificently amended rich, black self-regenerating soil along the river. Let me say that again.

It regenerates itself.

It’s alive.

People dig it up to sell, because when small amounts of it are added to depleted soil, it brings it back to life. You’d think that would be self-defeating, wouldn’t you? It’s a finite supply, how could anybody sell it off?

But it’s OK. It grows back.

Soil, like blood and breastmilk, is a living substance. Or it should be.

And, while the secrets of Terra Preta are not yet fully unlocked, one thing has become clear. Biochar is a major key in creating living, regenerative soil.

Biochar?

Activated charcoal. You know how activated charcoal draws everything into itself? If you have a stomach ache, take some and it pulls all the pathogens into itself. Well, it does the same thing in soil. It absorbs everything. Pathogens, microbes, nutrient…

It holds 3 times it’s mass in water and binds up
nutrients, releasing them as the plants’ exudates demand. It increases microbial biomass. See all the tiny holes in these photographs?
These provide habitat for microscopic soil organisms. They have a lot of predators and safe houses help them. And with increased reproduction of soil organisms, there is more functional diversity, in the form of increased metabolic and enzymatic activity.

It’s a recalcitrant form of carbon, which means it doesn’t break down. Compost gets used up and needs to be replenished, but biochar lasts for 1000s of years. Only complex molecules breakdown. Compost, obviously, is full of complex molecules. But biochar, being 90% carbon lasts and lasts. All the cellulose has been burnt off. It’s just down to the bare carbon atoms.

It acts as a permanent stage for the on-going life and death dramas of living soil. Complex, symbiotic interactions between soil organisms, including predator/prey relationships, are the most important thing. Plant health is a direct result of soil health. Being a non-biodegradable sponge that lasts forever and resists microbial degradation, biochar supports this beautifully. Unlike chemical fertilizers that kill soil life, thus depleting the nutritional value of plants. Biochar makes your plants healthier which, in turn, makes you healthier.

It also acts as protection from drought, flooding, under and over fertilizing. The great equalizer.

The Electrical Conductivity of Biochar

Biochar also improves the soil’s electrical conductivity. As carbon is negatively charged, it increases the Cation Exchange Rate, which is the ability of soil to hold onto positively charged cations. What are cations? Positively charged ions. Check out this 5 minute video.

You don’t need a PhD in organic chemistry to appreciate the many wonders of biochar. The people of the Amazon River Basin probably couldn’t’ve cared less about ions. They knew what worked, though. It was their long tradition. But it’s interesting. Plus, I’m out to make as many converts as I can!

You can get your soil’s Cation Exchange Capacity (CEC) tested. A rating of 10 to 15 is considered “Good,” and a rating of 25 is “Excellent.” The rating for Terra Preta is considerably better than excellent, with a rating of 222. Almost 10x better than what we would normally consider “Excellent.” That’s rather phenomenal, isn’t it?

Thermophilic

Being black, biochar makes your soil blacker. Dark soil absorbs more sunlight, so it stays warmer, longer and thaws out sooner in the Spring. A slightly extended growing season is always a good thing.

Biochar and Vermicomposting

Biochar works beautifully in conjunction with your red wigglers, too, becoming more concentrated during vermicomposting, with less of a reduction in volume. It provides needed grit for worms’ digestion tracts, which results in higher quality worm castings. They say it needs to be ground up real fine for worms. They have gizzards, like birds, and need grit to digest their food. My worms are not in bins, but living wild lives outside under the piles of woodchips and leaves. And, as I’m all about doing things with fewer steps, I leave the grit getting to them. They do actually know what they’re doing and what they need. If your worms are in bins, by all means pulverize the biochar for them. There simply isn’t room in most bin systems for a whole huge soup pot of biochar, like I’m adding every few days, throughout the winter.

Surface Area

Biochar has a huge amount of surface area. One gram, which is about a Tablespoon, has almost 2,000 square feet of surface area. That’s a lot of teeny tiny nooks and crannies! It’s like going to infinity and beyond, but into the infinitely small end of the scale.

But don’t crush it up too much, as that destroys the porosity. Surface area is important, but porosity is more important. Having lots of intact cells to move into makes bacteria and fungi happy little campers.

In researching this, I have found advice that says biochar can make up 10% of the soil profile, and advice that says it can be 60 – 80%. To me, this simply speaks to how much we have to learn about it. But also, it’s a good indication that we don’t have to worry about over-doing it. As easy as it is to make, it would still be hard to put that much into your soil.

Carbon Sequestration

It only follows that if something is good for the soil, it’s good for the environment, in general, being a continuum. Carbon sequestration is the process of capturing and storing atmospheric carbon in the soil. For every pound of carbon that’s sequestered, 31.5 cubic feet of carbon dioxide are removed from the atmosphere. This makes biochar a win-win-win situation.

How to Make Biochar

The best thing about biochar is that it’s incredibly easy to make, as well as virtually free, depending on where and how you get your wood.

If you do a search on YouTube, you’ll find a good 10,000 videos about making your own biochar through the process of pyrolysis. Pyrolysis is the heating up organic material in the absence of oxygen. There are many styles of ovens you can make, if you’re a welder. Personally? That sounds like too much work/money. Especially, since there’s still the added step of taking the newly made biochar, which is hydrophobic, into biochar that is hydrophilic. There are tars and resins that collect on the surface during pyrolysis. This repels water. Hydrophobic. It’s not a difficult step. All you have to do is soak it in water for a couple weeks. This breaks up the surface coating, and makes it able to absorb water. Hydrophilic. Soaking it in pond or river water is especially good, as all the water bacteria inoculate the biochar.

Inoculating the biochar, whether you make it the hard way, or the easy way, (which I will describe in a minute, here) is important. You want the right stuff to take up residence in all those microscopic pores. Because it’ll absorb toxins, too. So, better to get good bacteria from the start. You can even inoculate your biochar with specific nutrients, for specific plants, if you want to get fancy.

Easy ways to inoculate your biochar–

• Pee on it
• Put it in with your chickens or pigs for a while, so they can poop on it, eat it, poop it out again
• Layer it into your compost pile, leaves, woodchips, kitchen scraps, whatever you’ve got going
• Layer it into a hügelkultur
• Mix it with worm castings
• Mix it with baked and finely powdered eggshells
• Poor apple cider vinegar or the juice from your vegetable ferments on it
• Mix it with oats, which are a fungal food
• Mix and match any of the above however you see fit

Most people giving advice on this will describe lengthy productions of perfectly even lasagna layers of evenly ground up biochar pieces, sifted to perfect uniformity, among the other layers of biomass amendments. I have no intention of telling you not to do this. But to my way of thinking, this creates way too much work and organizing and…ugh! I’m old, in pain and don’t have any help. It needs to be easy. I just dump my current batch of biochar on a different place each time, spread it around a bit with a hoe and cover it up with something else. Top dressing, side dressing, mixing it in with a pitch fork are all good. As long as it’s covered with some kind of mulchy inoculant that will let it active in place.

The Easy Way.

Humans love to over complicate things. It was hidden in plain sight and so, took me a long time to find the easy way. It’s called Steam Cracking. This too is fancy, over complicated terminology. It’s quite simple. You pour water over hot coals.

Quenching hot coals makes steam. This makes the burning embers more absorptive by breaking open the pores. It also keeps the tars and resins from forming by washing out all those little cells. That’s all activated charcoal is. Leave it to soak in the water for 36 hours.

David The Good has a fabulous video for doing this the easy way. His easy way is still too hard for little old weakling me, but watch this 5 minute video to see just how easy it is to make 60 gallons of biochar in 2 hours. Then I’ll tell you about my way. He’s a good fellow to follow, if you’re not already. He debunks a lot of the over complicated nonsense.

Isn’t that simple?!

If you have mountains of brush and the energy to dig a trench, this is the way to go. I do not have mountains of brush, or the energy to dig a trench…or the energy to move it all afterwards. So I just use my woodstove. It’s longer and slower than what he’s doing. But it, literally, is no extra work at all. I have to bring in firewood anyway. I have to burn it anyway. One tiny extra step, and I have an ongoing supply of fabulous fertility!

When the firewood has burnt down to a bed of coals, I carefully rake it into a big stainless steel soup pot and pour water over it. Done.

I don’t scrape out all the red hot coals, I leave enough to catch the next pieces of wood on fire. Then do it again. Until the pot is full. Then, all I have to do is pull it in my wagon to the area I want to put it in.

Now, it does make a lot of steam, as you saw in David’s video. It does my way, too. But being a smaller container, it’s no big deal. It all gets sucked into the updraft of the woodstove. In looking for an easier way, I found out that Steam Cracking is “dangerous.” But if you have even a rudimentary brain in your head, and pay attention to what you’re doing, no. It’s no more dangerous than cooking. In the same way you would not put your hand into a pot of boiling potatoes, you do not stick your face into the Steam Cracking steam.

You very well may not have a woodstove. Most people don’t, these days. But you could create your own variation with a nice fire pit. You could make it with rocks or buy one of those attractive metal ones. Then, just shovel the bed of coals into a big pot. (Stainless is better than galvanized. Galvanized will rot out after a while…especially if you pee in it, which you should.)

Watch your face, and pour in water until it stops making steam. You can fill it up with a lot of water, if you want, so the charcoal pieces are floating. Then the next addition of hot coals will be extinguished from the bottom. Watch what you’re doing, but do not be afraid. Before you know it you’ll be a very proud gardener, indeed!

I would love to hear about YOUR adventures in biochar. Leave a comment!