Biochar! The verdict is in: it works. And you should do it.

October 7, 2014

NOTE: Images in this archived article have been removed.

Badgersett Research Farm

 If you’ve been hanging around green or sustainable news and discussion places in the past five years, you’ve almost certainly run into articles, video, and TedXes on biochar, and how it “could” or “can” or “will” save the world. You may also know it as terra preta.

Biochar has been seen doing so many things in so many places, that it is incredibly easy for intelligent readers to start muttering “snake oil" by the second paragraph. But the terra preta soils are astonishingly persistent – they keep nudging. So top academic researchers around the world started poking at it, trying to measure “if” and “how much” and “how.”

The first thing that happened was that they all came up with different results – not “no,” but different and a bit confusing. Caution set in. So since 2005 there’s been a huge amount of discussion and enthusiasm; but very limited action – as far as getting lots of “farmers” involved… until, maybe perhaps, now…

Why do you need an article from me to tell you this? Because research scientists are trained and retrained to never, ever, say “yes” or “no.” Because, in truth, science does not give “yes” answers with perfect certainty. But for plain folks, sometimes you just want the simple version. I am a scientist, in fact- but I’m also a maverick, not attached to a university, so I can break the rules once in a while.

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Home made biochar. Photo by K.salo.85 on December 2013. Creative Commons via Wikimedia Commons 

Ok, top to bottom (briefly!):

Terra preta de indio (“Indian black earth”) is the name given in the Amazon to deep black soils found in many places. They are highly and persistently fertile, often farmed by the local folks.  

Typical rainforest soils are the opposite; very infertile, because the trees already have all the nutrients tied up in wood, and red, not black. After decades of argument, it is now agreed; these soils were created, somehow, by the Native Americans, and they’re black because they’re full of charcoal, which is also what makes them fertile. The details are very thorny – but that’s all now accepted.

Biochar is our modern name for charcoal designed to copy the results of the Amazon terra preta soils. Why do that? 

Terra preta soils:

  1. hold on to nutrients, but make them available to plants
  2. hold on to water in droughts, but makes the water available to plants
  3. will raise the pH of acid soils so nutrients are more available
  4. supports a rich soil microbial community
  5. make clay soils drain water better AND
  6. make sandy soils hold water better, and
  7. grow crops bigger and
  8. healthier. 
  9. Oh, and remember I said the terra preta soils are persistent? The carbon in that charcoal in the soil can be 2-3 thousand years old. Maybe 4 or 5.


Normal “organic matter” carbon, as in compost,  has a “soil residence” of 10-100 years. Then it’s back in the air as CO2. The thousands of years is the bit that really got excitement spreading – the idea that we might be able to “sequester” carbon in the soil this way – maybe even “enough” carbon to make a difference to climate change. A bunch of big name folks of diverse flavors have done the math and agree: it’s not impossible.

So you can see where the “snake oil!” warnings would be flashing like mad. With the caveat that every single word in the previous paragraphs is still capable of setting off a heated disagreement between experts, it is nonetheless true that the paragraphs are now agreed to be “true” (like around 90%) by the world biochar research community.

We even know some major parts of how biochar works now. How does it last so long? When charred at correct temperatures, the biomass being charred (any plant material, even manures) has pretty much everything except the carbon cooked out of it. But the structure of the wood, or grass remains It is very complex and stays that way.

When you char cellulose and/or lignin, the hydrogen, oxygen, and nitrogen “cook off” as gases, and the carbon left behind then makes chemical bonds to the carbon atom next door. Other elements like potassium stay inside the char as a kind of ash-available nutrients. But virtually all of the carbon is now linked only to another carbon atom – and microbes can’t/don’t attack carbon-carbon bonds. That’s not “food” for them and they leave them alone. For thousands of years, at least.

This presentation showing the microscopic structure of wood  is great (see slides 9 and 10). It  illustrates why so many scientific studies have been conflicting: the microstructures of softwood and hardwood are pretty different. Grass is different yet, etc. What you start with, how hot, and how long it’s cooked – all make a difference to how the biochar performs.

Another major factor that has only been truly resolved in the past few years is “what else is in it” when you put it into the soil. Chars that have been cooked so that virtually nothing but carbon is left may be very slow to show crop benefits. Chars cooked so that some molecules that can feed microbes are still inside the char will show benefits sooner.

And it’s well demonstrated that “charging” your char before incorporation is probably better yet: soaking the char with active microbes from compost or something similar. Possibly soaking some nutrients into it will let the char go to work much faster. Sorting the details there is a current biochar research focus.

Some things biochar is not. It’s not a “fertilizer” – but it does hold nutrients. So depending on your soil, you may need to add less, and you can also expect to have less risk of nutrients escaping into surface water or aquifers. It is not a quick fix for atmosphere CO2 and climate change.

In order for farm use of biochar to make any difference on a global scale it would need to be used very widely. That won’t happen instantly. Many doubt that “farmers” will be interested in doing it at all – but there is one big reason they will. Money. The pioneering farms who start using biochar now will very quickly document and show that incorporating biochar will affect any farm’s “bottom line” — positively. It will put money in the farmer’s pocket. Will. That is how and why farmers always change – they see a neighbor doing something new, and making money at it.

Re: the disagreement potential. For a very simple example, start with the wrod “farm”. It’s astonishing how differently folks construe that word. And consequently how different folks’ expectations are when it’s suggested that “farmers will do this” or “farmers will never do that.”

This is what I think a “regular farm” is: We’re in the extreme northern edge of the Corn Belt. I’m surrounded by "mainstream" farms. Our neighbors are wonderful, and I’ve been here almost 40 years. The typical family farm here is two brothers and their wives (don’t give me a hard time…) and kids, operating 800-1500 acres, including a beef herd of around 100 head. Cow-calf operations usually, some dairy.  If you go only 30 miles west, you can add 1,000 acres to those numbers and delete the cows because the land is dead level there. I’ve got hills. And there are forests everywhere, usually in small bits, but there’s abundant tree seed available, and lots of birds to carry it – into every fence line that exists.

Disagreement over details abounds and we do need to resolve a lot of them. Eventually, maybe even “soon." But our contention is that we know enough to start doing biochar: making it, getting it into the soil, and getting it into the hands of “regular farmers” – right now. We’ll improve as we go along, but just using what is now known, the farmers, soil, crops, and atmosphere will all benefit.

The bottom line, today: your soil will benefit, your crops will benefit; and yes, the atmosphere will benefit – a little. But you know how that works – “a little” times thousands adds up.

Badgersett Research Farm (me – us) – is not a center for biochar research. Those fellows have mostly never heard of us. We’re the other end of the equation. We’re farmers. Oddball farmers, to be sure. Our immediate farmer neighbors love to introduce us at weddings, so they can hear “Oh, yah! I’ff heard o’ yü folks! Yür ta ones from ta nut farm!” We smile in gracious acknowledgement.

[Editor’s note: For background on the farm, see
Badgersett: Bringing Woody Agriculture into the Mainstream and
Come on Home!: Ecological Agriculture and Sixteen Wonderful Farms that Point the Way
, both published at .]

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We grow and breed woody crops, three different ones, and we are scientists. But according to my tan and our sweat, we are also farmers. As scientists, we’ve been involved in international climate conferences since 1988. We became aware of terra preta long before it was agreed that those soils are man-made, and were aware of biochar when that became the topic.

As farmers, particularly tree breeders-growers, biochar hit us most forcefully after about five years of watching our thousands of trees get bigger and bigger, and wondering (desperately at this point) how we were going to cope with all this biomass. Thousands of small trees that need to be culled – in thousands of places. And the hybrid (“neohybrid”) hazels that need to be cut to the ground every 10-12 years or so. That was the push for us to design a farm-size mobile biochar system. Sized for our needs – which will fit for thousands of other farmers too. So as not to rudely surprise you, yes, we are running a Kickstarter right now to raise funds to fully design, build, and test operate one that will “fit”.

We’d been aware for a number of years of the efforts of various permaculture-ish folks to build “farm scale” biochar tools. One of the best in North America has been New England Biochar, which now makes a well tested mobile “retort” for farms (we call it a “kiln”). Folks in Australia are well advanced too, as Biochar Farms shows.

Our efforts are built on these folks’ shoulders. We hope someday they’ll build something on ours, too. That’s how we can move forward. But for the moment, nothing they have designed would fit both our specific needs and budget, nor would they fit for our corn and bean neighbors. The reasons are numerous, and way too involved for this article. Just let me say work flow, materials logistics, worker requirements, and we’ll give you details somewhere else (to be determined!).

What we envision is:

  1. Most farmers will build theirs using as little as $4,000 in local materials, plus labor and control kit.
  2. The control kit, which will be professionally designed, fully adjustable for everything we can think of, we hope to sell for around $250 when producing at scale. It will be very easily adapted for kilns both bigger and smaller than this one.
  3. This piece of equipment should last 10 years if abused, 20 years if shedded, and be capable of essentially constant operation.
  4. It can be operated by one worker safely, moved anywhere on the farm a hay-wagon could go, and fired either in the field or anywhere the extra wood gas could be used for electric generation or space heating. The char output, either incorporated into crop lands on the farm or sold for cash, together with other benefits of operating it, should pay the salary of the operator.
  5. It will be “road legal” as farm equipment; so it can be moved without permit silliness to other farms. It could be rented to neighbors, or shared, even operated in a suburb to pick up branches and leaves…
  6. It will be emissions legal starting with the second prototype.
  7. Designs – except possibly some aspects of the control kit – will be available from us, so others are free to improve and adapt it.
  8. 9., 10… There is, indeed, more; but enough is enough, right? The “more”, and our Kickstarter video and link, is here:


We hope you’ll take a look! And we hope you will become Backers- we believe this is the best way to make biochar available very soon to many “farmers” – large and small; and many communities too. It’s not a “fit” for every situation- but it is a fit for thousands.

Philip A. Ruter is a scientist and farmer at Badgersett Research Farm.

Tags: agriculture, biochar