Terra Preta: Biochar And The MEGO Effect

This month's edition of National Geographic has a feature article on "Soil", which looks at the steady degradation of agricultural land and the problem this poses in world where the population is heading for 9+ billion people - effectively calling attention to the "peak dirt" problem (however soil is renewable, so any "peak" should be able to be reversed if sufficient time and effort is put into doing so).

The article uses an acronym I've never come across before to describe the problem faced by those trying to draw attention to the issue: MEGO (My Eyes Glaze Over) - a phenomenon which should be familiar to anyone who has ever talked about peak oil, global warming or any of the other "limits to growth".

This year food shortages, caused in part by the diminishing quantity and quality of the world's soil, have led to riots in Asia, Africa, and Latin America. By 2030, when today's toddlers have toddlers of their own, 8.3 billion people will walk the Earth; to feed them, the UN Food and Agriculture Organization estimates, farmers will have to grow almost 30 percent more grain than they do now. Connoisseurs of human fecklessness will appreciate that even as humankind is ratchetting up its demands on soil, we are destroying it faster than ever before. "Taking the long view, we are running out of dirt," says David R. Montgomery, a geologist at the University of Washington in Seattle.

Journalists sometimes describe unsexy subjects as MEGO: My eyes glaze over. Alas, soil degradation is the essence of MEGO.

One subject that features in the article is soil restoration, including a look at "terra preta" - rich, fertile artificial soils found in the Amazon. In this post I'll have a look at modern day techniques to produce terra preta (often called biochar or agrichar) which have the potential to increase soil fertility, generate energy and sequester carbon all at the same time.

The History Of Terra Preta

Terra Preta ("black earth") was discovered by Dutch soil scientist Wim Sombroek in the 1950's, when he discovered pockets of rich, fertile soil amidst the Amazon rainforest (otherwise known for its poor, thin soils), which he documented in a 1966 book "Amazon Soils". Similar pockets have since been found in other sites in Ecuador and Peru, and also in Western Africa (Benin and Liberia) and the Savannas of South Africa. Carbon dating has shown them to date back between 1,780 and 2,260 years.

Terra preta is found only where people lived - it is an artificial, human-made soil, which originated before the arrival of Europeans in South America. The soil is rich in minerals including phosphorus, calcium, zinc, and manganese - however its most important ingredient is charcoal, the source of terra preta's color.

It isn't entirely clear if the Amazon Indians whose old settlements terra preta is found at deliberately created the soils or if they were an accidental by-product of "slash and smoulder" farming techniques, though the emerging consensus seems to be that the Indians deliberately created the material, with some early European accounts in the area noting the practice still being performed.

The key ingredient is apparently the activated carbon in the charcoal. Activated carbon has a complex, spongelike molecular structure - a single gram can have a surface area of 500 to 1,500 square meters (or about the equivalent of one to three basketball courts). Having this material in the soil has several beneficial effects, including a 20% increase in water retention, increased mineral retention, increased mineral availability to plant roots, and increased microbial activity.

It has also been shown to be particularly beneficial to arbuscular mycorrhizal fungi, which form a symbiotic relationship with plant root fibers, allowing for greater nutrient uptake by plants. There is speculation that the mycorrhizal fungi may play a part in terra preta’s ability to seemingly regenerate itself.

Pyrolysis and Eprida

Modern day producers of biochar (agrichar) take dry biomass and bake it in a kiln to produce charcoal. Biochar is the term for what is left over after the energy is removed: a charcoal-based soil amendment - this process is called pyrolysis. Various gases and oils are driven off the material during the process and then used to generate energy. The charcoal is buried in the ground, sequestering the carbon that the growing plants had pulled out of the atmosphere. The end result is increased soil fertility and an energy source with negative carbon emissions.

Eprida is a company founded by Danny Day, which is attempting to commercialise the idea by building systems that turn farm waste into hydrogen, biofuel, and biochar (see here for a short movie explaining their process).

The Eprida technology uses agricultural waste biomass to produce hydrogen-rich bio-fuels and a new restorative high-carbon fertilizer (ECOSS) ...In tropical or depleted soils ECOSS fertilizer sustainably improves soil fertility, water holding and plant yield far beyond what is possible with nitrogen fertilizers alone. The hydrogen produced from biomass can be used to make ethanol, or a Fischer-Troupsch gas-to-liquids diesel (BTL diesel), as well as the ammonia used to enrich the carbon to make ECOSS fertilizer.

We don't maximize for hydrogen; we don't maximize for biodisel; we don't maximize for char...By being a little bit inefficient in each, we approximate nature and get a completely efficient cycle.

The potential power of biochar lies in this closed loop production process , where agricultural practices involving biochar production see increasing returns of crop yields, energy and soil fertility over time.

Biochar also has potential to address problems such as waste disposal and rural development. A significant proportion of the world's population relies on charcoal as a cooking fuel, the production of which drives deforestation in Africa and other places.

Replacing traditional charcoal kilns with modern pyrolysis units could reduce the demand for wood from forests by increasing the efficiency of energy production and adding the ability to use any source of biomass, including agricultural waste products. This would also help to reduce respiratory diseases in the developing world, particularly amongst children.

There has also been speculation that pyrolysis could be a useful technique for dealing with the huge swathes of Canadian forests that have been killed by pine beetles recently.

Some industry participants believe that energy, rather than agriculture, will be the key driver for adopting biomass pyrolysis. Desmond Radlein of Dynamotive Energy Systems has been quoted as saying "It is wishful thinking that people will switch to renewable fuels unless it is cheaper. All of this is tied to the price of oil; as it goes up, many more things are possible."

Another company active in the pyrolysis sector is Best Energies. Technical Manager Adriana Downey recently had an interview with Beyond Zero Emissions, talking about some of the pilot programs they have been running and plans to build the first fully commercial scale pyrolysis plant in Australia.

Lukas's program with the NSW DPI (Department of Primary Industries) in Northern NSW have basically taken some of the agrichar material that we've made here at Best Energies and they've been trialling that material in different agronomic applications to see how the agrichar, when its applied, can help crop-productivity and improve the sustainability of agriculture as well as, and what you guys are more interested in, sequester carbon long-term in soils and also decrease the potent greenhouse gas nitrous oxide emissions from soil. ...

The agrichar when it's applied to the soil has a good effect on the general physical structure of the soil. Because the agrichar has a really high surface area, it means that there's lots of pores in the soil which can then retain moisture and act as little reservoirs for the water to be retained in the soil. As well as this, all of the surface area helps to bind nutrients in the soil and also provides a microhabitat for micro organisms in the soil which are essential for the natural processes in the soil which allow micro organisms to flourish.

Carbon Capture Potential

There is a large difference between terra preta and ordinary soils - a hectare of meter-deep terra preta can contain 250 tonnes of carbon, as opposed to 100 tonnes in unimproved soils from similar parent material, according to Bruno Glaser, of the University of Bayreuth, Germany. The difference in the carbon between these soils matches all of the carbon contained in the vegetation on top of them.

The ABC's "Catalyst" program last year had a feature on "Agrichar – A solution to global warming ?" (shown below) in the lead up to an international biochar conference in Terrigal, NSW, which included Tim Flannery talking about the potential for sequestering gigatonnes of carbon in the soil.

This year's International Biochar Initiative conference has just been held in Newcastle-upon-Tyne in the UK.

It is not yet clear what the limits are to how much biochar can be added to the soils using these techniques, however some fairly extravagant claims about biochar's capacity to capture carbon have been made. Soil scientist and author of "Amazonian Dark Earths: Origin, Properties, Management" Johannes Lehmann believes that a strategy combining biochar with biofuels could ultimately offset 9.5 billion tons of carbon per year - an amount equal to the total current fossil fuel emissions. Lehmann also notes that unlike biodiesel and corn ethanol, biochar doesn’t take land away from food production.

If true, this would be an interesting form of geoengineering to try and reverse the effects of global warming (and one far less risky than some of the alternatives proposed) but I would still question our ability to turn all the world's oil, coal and gas reserves back into rich soil via burn - atmosphere - pyrolysis loop.


A number of criticisms have been made about biochar. These include:

* The technology to implement the process is still immature.
* Scientists don’t know how much charcoal farmers should use, how they should apply it, or which feedstocks work best.
* Farmers are reluctant to spread unproven products on their fields, so the few companies manufacturing biochar have struggled to find buyers.
* Charcoal production can generate toxic waste if performed incorrectly.
* The energy needed to produce, transport, and bury biochar could outweigh the carbon savings.
* Some analysts say the economics of the process will not be acceptable until carbon markets are established, allowing farmers to earn carbon credits for applying biochar to their fields.
* Some environmental activists claim that applying the process on a large scale would result in further rainforest clearing which would actually degrade soil quality and increase global warming.

Rhizome In The Amazon

Jeff Vail recently had a post on a "Rhizome Template in the Amazon ?", which looked at a paper by Mark Heckenberger suggesting that a dense civilization of networked villages once existed in the Amazon, which Jeff noted was interesting because it "appears to show a form of organization that permits density without significant hierarchy".

The paper shows that the Xingu region of the Amazon was once populated by a grid-like pattern or villages, each connected by a precisely aligned network of roadways (the Xingu river is the Amazon's second longest tributary, with the region currently experiencing tension over plans to dam the river).

Here's an alternate mode of organization--a networked "grid," "lattice," or "peer-to-peer" structure of small, minimally self-sufficient villages, or "rhizome" as proposed in my article The Hamlet Economy. The Xingu settlement structure seems to consicously model itself in the latter pattern. Heckenberger even notes that each village was surrounded by a buffer zone of "managed parkland," exactly the kind of fall-back, resiliency-enhancing production zone that I recommended for rhizome. Here's a link to a satellite image of one section fo Xingu settlement.

Did this Xingu civilization really develop a dense, ecologically sustainable civilization without hierarchal structure? Or did they simply find a new way to impose hierarchy without developing the signatures of "central places"? Was this a conscious reaction to prior abuses of hierarchy, or simply an expedient to survival in the dense forrests and poor agricultural soils of the Amazon? We don't know the answers to these questions at this time, but the research of Heckenberger and his colleagues suggests that there is still a great deal for us to learn from the past about how we can best live in the future

Heckenberger also examined the terra preta pockets in the region, which is described briefly in an interesting article by Charles Mann in The Atlantic Monthly called "1491".

Scientific American also notes the correlation between the lost cities of the Amazon and terra preta in "Ancient Amazon Actually Highly Urbanized", as does The Vermont Quarterly in "Pay Dirt".

Terra preta, Woods guesses, covers at least 10 percent of Amazonia, an area the size of France. It has amazing properties, he says. Tropical rain doesn't leach nutrients from terra preta fields; instead the soil, so to speak, fights back. Not far from Painted Rock Cave is a 300-acre area with a two-foot layer of terra preta quarried by locals for potting soil. The bottom third of the layer is never removed, workers there explain, because over time it will re-create the original soil layer in its initial thickness. The reason, scientists suspect, is that terra preta is generated by a special suite of microorganisms that resists depletion. "Apparently," Woods and the Wisconsin geographer Joseph M. McCann argued in a presentation last summer, "at some threshold level ... dark earth attains the capacity to perpetuate—even regenerate itself—thus behaving more like a living 'super'-organism than an inert material."

In as yet unpublished research the archaeologists Eduardo Neves, of the University of São Paulo; Michael Heckenberger, of the University of Florida; and their colleagues examined terra preta in the upper Xingu, a huge southern tributary of the Amazon. Not all Xingu cultures left behind this living earth, they discovered. But the ones that did generated it rapidly—suggesting to Woods that terra preta was created deliberately. In a process reminiscent of dropping microorganism-rich starter into plain dough to create sourdough bread, Amazonian peoples, he believes, inoculated bad soil with a transforming bacterial charge. Not every group of Indians there did this, but quite a few did, and over an extended period of time.

When Woods told me this, I was so amazed that I almost dropped the phone. I ceased to be articulate for a moment and said things like "wow" and "gosh." Woods chuckled at my reaction, probably because he understood what was passing through my mind. Faced with an ecological problem, I was thinking, the Indians fixed it. They were in the process of terraforming the Amazon when Columbus showed up and ruined everything.

Scientists should study the microorganisms in terra preta, Woods told me, to find out how they work. If that could be learned, maybe some version of Amazonian dark earth could be used to improve the vast expanses of bad soil that cripple agriculture in Africa—a final gift from the people who brought us tomatoes, corn, and the immense grasslands of the Great Plains.

All in all I think biochar is worth exploring further in some depth.

Further Reading:

Nature: Putting the carbon back "Black is the new green": http://www.nature.com/nature/journal/v442/n7103/full/442624a.html

Biochar overview from Cornell University: http://www.css.cornell.edu/faculty/lehmann/biochar/Biochar_home.htm

Terra Preta web site from the University of Bayreuth http://www.geo.uni-bayreuth.de/bodenkunde/terra_preta/

The Earth Science Forum: http://forums.hypography.com/earth-science/3451-terra-preta.html

Biochar summary from Georgia Tech: http://www.energy.gatech.edu/presentations/dday.pdf

Terra preta mailing list: Terrapreta@bioenergylists.org http://bioenergylists.org/mailman/listinfo/terrapreta_bioenergylists.org

FAO: Organic Agriculture And The Environment http://www.fao.org/docrep/005/Y4137E/y4137e02.htm

WorldChanging: A Carbon-Negative Fuel http://www.worldchanging.com/archives/007427.html

Hen and Harvest: Black Magic http://henandharvest.com/?p=118

Peak Energy: On population growth and the green revolution - "The Fat Man, The Population Bomb And The Green Revolution" http://peakenergy.blogspot.com/2007/10/fat-man-population-bomb-and-green.html

Peak Energy: On worms and soil - "The Turning Of The Worm" http://peakenergy.blogspot.com/2007/01/turning-of-worm.html

Peak Energy: On Mycelium - "Nature's Internet: The Vast, Intelligent Network Beneath Our Feet" http://peakenergy.blogspot.com/2008/07/natures-internet-vast-intelligent.html

(Hat tip to Erich J Knight and Aaron Newton for providing some of the links used in the post)

Cross-posted from Our Clean Energy Future.


This is an excellent post. Certainly the sort of "carbon geosequestration" that I can live with!

I imagine that most of the scientific unknowns could easily be answered with only a fraction of our current "clean coal research" budget. (And if you ask me, I think plants will end up being the only workable solution to getting rid of our coal emissions, since I can't see people giving up their addiction to coal...)

While reading your article, I started to worry about "scalability", "centralisation", "transport" etc... And then it suddenly hit me. Biochar is an ideal decentralised solution!
- Have each wheat farmer put in a stand of the local eucalypts on a percentage of their land, set up a small processing plant and churn out their own biodiesel and topsoil dressing, as well as keeping the dreaded dryland salinity at bay. (Actually, why not put the biochar plant on wheels and trundle it between farms like a contract wheat harvester!)
- Plantation timber harvesters should have a mobile unit with them, making their fuel and eliminating most of the current CO2 emissions from waste burning, etc.etc.


Thanks Cretaceous.

The last section on the old Amazon civilisations that generated the terra preta in the first place was intended to demonstrate the point you make - its appropriate for use in a very decentralised environment.

I thought the phrase "terraforming the Amazon" was a striking one too - the sort of thing which needs to be done in a number of degraded modern landscapes (some of which are here in Oz).

This is brilliant. Thank you.

I like the article.
I have built a "retort" kiln for the production of charcoal. It uses a standard 275 gallon home heating oil tank and a 55 gallon barrel. Gasses driven off of the "load" are piped under the barrel and burnt to give addition heating.

So far what I have learned...
Since I have no thermometers I can only say that it takes a substantial amount of heat over a long period of time (hours to days)to get the process to be self sustaining. This may be my understanding of "dry" in the "load" is not the same as "oven dried". Once started, however, gasification is nothing short of amazing.

My tank is not insulated which I think would help. I plan to use this "kiln" to heat my shop and get charcoal at the same time. Some modifications are needed to provide combustion air and mixing to get better use of the gasses.

Grinding charcoal is very messy. I have built an electric grinder that uses 2 carbide saw blades 1/2 inch apart with a hopper above. This gives me charcoal less than 3/8 inch at the biggest.

It would be easy to divert the gasses from my kiln to other purposes. There are a number of different chemicals that can be "distilled" from wood. This "is" what you are doing, perhaps you backyard moonshiners can relate practical experiences.

While there are internet sites that deal with retort kilns the amount of information that I have found that relates to different temperature ranges to distill different chemicals is lacking in a consolidated site. I suspect that MSDS sheets for know compounds might have the very best information.

No measurable result on plant growth. We are already blessed with highly fertile soils so your result might be more measurable than mine.

best hopes for increased sanity...


Unfortunately, we're already "terraforming the Amazon," in the worst possible way:

Global warming aside, southern Amazon forest cover may fall to 20% by 2016
Rhett A. Butler, mongabay.com
September 3, 2008

Forest cover in the "Arc of Deforestation" of southern Amazonia will decline to around 20 percent 2016 due to continued logging and conversion of forests for cattle pasture and soy farms, report researchers writing in the journal Environmental Conservation. The results are independent of impacts resulting from climate change, which some researchers say could dry the Southern Amazon and turn it into a tinderbox.

We're just cutting it down and burning it up. Climate change will finish it off in other couple of decades. (By the way, that's 90 gigatons of sequestered carbon we'll be releasing, once the whole forest is destroyed.)

Maybe is should be called "marsaforming" ... turning it into a rusty desert with a CO2 atmosphere?

Yes, excellent post Gav. This is an important area of study. Here in the 4th corner of the U.S. we have some folks working on terra preta as well.

To add to your "Further Reading" list, check out "Charcoal, Agriculture and Climate Change" by Richard Haard, PhD. at the Energy Bulletin.

Thanks - I missed that article when it came out - its a good addition to the list.

Thanks for this great introduction to terra preta and its modern day variant.

We try to implement biochar at the tropical forest frontier, where the technique was first developed (thousands of years ago, not only in the Amazon, but there's evidence for it in Western Africa too) and where the first modern in-depth and longest running field trials can be found (near Manaus, running for over 5 years now). However, our focus is to try it out in Central Africa.

It is here that the concept possibly yields the greatest advantages, because farming on these nutrient-poor, acidic tropical soils is notoriously difficult. Because these soils lose their fertility so quickly, farmers are forced to engage in a slash-and-burn cycle. With increased population pressure, this type of farming is fueling deforestation, but it is also keeping these communities in extreme poverty.

So our focus is in Central Africa, where we aim to make biochar the core of an integrated sustainable development model. In theory, biochar should (1) maintain soil fertility, (2) thus reduce deforestation and short-circuit the slash-and-burn cycle, (3) strengthen food security (because yields also increase), (4) make available modern energy, yielding both electricity and char obtained from using field residues, which are currently burned (thus once more reducing deforestation, because local communities use wood), and, (5) as an interesting side-effect, sequester carbon permanently (possible carbon-credits could make the concept self-financing).

Obviously, this is a model, and many questions remain as to its viability. But if the model works, we perhaps have a concept that can tackle some of the most immediate problems amongst these communities (food insecurity, deforestation, soil destruction, energy insecurity, climate change), - simultaneously. Please do check it out, we would very much appreciate your input, thoughts, criticism and suggestions.

The "Biochar Fund" website can be found here: http://www.biocharfund.com .

Our ultimate aim is to transition from slash-and-burn systems in which a small number of low yielding crops is used, to a non-deforestation farming concept based on agro-forestry and reforestation. This way, we can sequester carbon in soils, and use these fertile soils to grow food trees on them, sequestering even more carbon.

One of the most important endorsements of Biochar in recent months was by Dr. James Hansen NASA's atmospheric expert, Global warming solutions paper and letter to the G-8 conference, and coming article in Science,

We need to Start with the youth too, here is a great school program;

With the Charcoalab Project, you can take part in international research on charcoal and help discovering solutions to Earth's global warming issue!
Through this website, you can learn more about the Charcoalab Project and discover how you can participate in the project. It is easy, hands on, fun... and could really help the planet! If you are ready to become a certified charcoal tester, order your Charcoalab Kit!

To visualize the soil food web, and understand how MYC / VAM are the nutrient Super highways and chemical communication internet for plants, posted on the TP/Bioenergy site, this presentation is one of the best I've seen to get across how MYC symbiotically permeates all in roots & soils, and elucidates often hidden benefits. Very nice pictures;


The microbe world has done so much for us, they deserve rewards,
a nice biochar house, with a full fridge, sewer& water service, highways, telecommunications and universal soil web health care. A poster at the TP list, speaking on biologic productivity, put it this way;
"Microbes like to 'sit down' when they snip apart molecules".

Thanks Erich.

The mycellium subject is one worth exploring further - I only just touched on it in the post.

The last link in the "recommended reading" section has a few good pointers - its also worth watching this TED talk too.


The mycelium subject is one worth exploring further

Ohhh, a topic I could actually write a key post on.
(not a big key post mind you. And I have doubts on the interest for this forum - it is far off field for TOD.)

If one wishes to explore the topic - visit Paul Stamets at http://www.fungi.com (Fungi Prefecti)

The fungi are the way the hard to break chemical bond of P is made bio-aviable to the plants. The fungi increase the effective root mass for gathering water and the plant gives up sugar to feed the fungi.

Want to damage/destroy the fungi?
Till the soil
Provide P in a loose form so the plant doesn't need the fungi

Well - it might be a bit off topic but I'll happily publish a guest post at TOD ANZ (though I can't promise it would make the main page).

If you link it back to biochar (or non-oil dependent agriculture) there is a good enough link for me.

I'll dig out my $200 reference book and whip up something after I re-glue other people's computer systems back together.

And if you were going to structure a 'research' project on adding biochar to 'previously glaciated soil' - what protocal(s) would you choose?

OK - just send me an email once you've got a draft ready.

The bacterial origin of biochar makes sense. The pre-Columbian Amerindians had a low energy, low physical technology culture , and this is the state upon which the west is about to embark.

Should this very elegant solution prove correct then one can envisage a simple path to a sustainable agriculture.

Place starter culture in several mulch pockets over the field and then feed the culture by felling the trees, shrubs and grasses that is the native covering of the field - leave to ferment and then you have a biologically active field that will sustain food crops for millenia.

The bacterial soup could harvest essential elements from the atmosphere and hold them in the soil for use by the plants.

Wow.. lets keep our fingers crossed.

A simple experiment would be to take a few cups of the original terra preta and place in mulch and see if it grows!!

For the small-scale, backyard gardener, activated charcoal is very expensive to buy. As I have a wood-burning fire for heating, I've taken to digging in the ashes & charred bits into the soil and/or compost heap. I have no idea if this is will encourage eventual formation of terra preta or whether I'm potentially damaging the soil instead. Has anyone else tried a low-tech, low-cost, backyard scale biochar implementation?

I can't remember the details off the top of my head, but I vaguely remember reading that just dumping charcoal into your soil isn't a good idea - there is some process to be followed to do it correctly (if you read all the links in the post you'll come across the right information eventually).

On the other hand this guy thinks it is fine to just add to soil (preferably with compost):


Wood ashes contain lye. I think Big Gav has a point. A bit of research first could be a good idea.

It's just that it makes your soil more alkaline. However, if you do regular additions of compost, which is slightly acidic, then it all balances out.

Plus, you have to consider relative amounts. One shovelful of ash on each square metre of garden a year, that's not going to change the soil's acidity. But a shovelful a week will.

But in general, if for each shovelful of ash you put in, you also put in a shovelful of compost, things will balance out nicely.

Virtually every county has a County Agent's office. When I was farming, a long time ago, even New York City had one. Go to the agent's office get a soil sample bag and directions on how to take a soil sample. Follow the directions and return the sample and wait for the results. It's free and it will tell all you need to know about your soil. (Alkaline, acid, % organic matter, fertility, and so on.) It is also simple to do.

Wood ashes are not the same as charcoal. They do have micronutrients, but the ashes will be alkaline. The pH of compost is not necessarily acidic and cannot be counted on to neutralize the wood ash - though it will probably buffer the addition. If you have added a lot over the years, you've sweetened your soil. Get a soils test.

I used to add wood ashes to my compost. It was most certainly not acidic. Been there done that mistake.

cfm in Gray, ME

Here's a link I found to a rather busy forum of people who have used charcoal in their soil talking about it's creation, application, results...


Soil Scientist Phil Small established the WIKI "Gardening with Biochar FAQ" at http://biochar.pbwiki.com/

It includes instructions for making biochar in garden-scale systems and for using it. He also maintains the soil science blog Transect Points that includes a number of posts and links on bichar. Not very active at the moment, I suspect he is very busy working in the field as a practicing soil scientist during this season.

Gary Jones, a grazier, has a number of thoughtful posts about soils and biochar in his blog Muck and Mystery.

Don't laugh, but I've been buying 20 lb bags of wood charcoal
at WallyWorld for $5.00 and burying it in my garden soil ..
My tomatoes seem to like it !!

Triff ..

hi commuter,

we have been using charcoal in our soil for the last two years. we make our own, using a homemade, cheap method, utilizing a 55 gallon drum. this is not wood ash, it's charcoal, made by burning wood under limited oxygen conditions. the drum has 6 holes , 5 in a star pattern in the center and one on the outer area , all in the bottom of the drum. the drum sits on bricks , with 3 "tunnels" leading to the holes. we use lilac cuttings , because they are small and hardwood , to avoid the pitch of pines. we don't have to break it up afterward, we just add it directly to the soil, with other amendments , like compost and sulfur( our soil is basic). we start the fire with a small amount of twigs in the bottom, and add twigs until full. then we put the top on most of the way, to burn off the volatiles. after the smoke turns clear, we close up the tunnels with sand and secure the top. come back the next morning, and harvest charcoal. beer has been known to make the task more enjoyable we find that things grow healthier,leaves are glossier, vegetables taste ( much) better and seem to yield higher.

Great stuff Big Gav.

Jeff Vail's ideas about rhizome parallels stuff I've been pondering. My thinking was specifically non-hierachical.

a networked "grid," "lattice," or "peer-to-peer" structure of small, minimally self-sufficient villages, or "rhizome"

That's where we are going.

Would there also be an option to use available manufactured type appliances, for instance approximately ~1 kW with solar energy systems at the point of use. For example, the quick cooking time, requires relatively less energy. Where energy = power * time. Besides cultural and other issues, the solution would be, for instance, a photovoltaic array, inverter, charge controller, batteries, other balance of systems, ... simplifies the situation?

Hi Gav,
Great article and excellent links.
MEGO is the acronymn that certainly describes the reaction from folks when I introduce them to the concept of terra preta.
However that vanishes when they see my garden or taste its produce.
Below is a useful link from a blacksmith for building a retort than can produce appreciable amounts of charcoal if one has the area and tinkering skills.
It has inspired me to design and build retorts that generate steady amounts of char and help heat my home.

Another site for those wishing to produce char while driving about.

Thanks for those links - its good to see people doing DIY projects in this area - especially if you are getting energy and char from your process.

Wow! I got all excited about this. I had read the Scientific American article, this brings back some ideas I had then.

I just wonder if I am missing something though.

"Carbon dating has shown them to date back between 1780 and 2260 years."

What then disturbed the system? It couldn't have been the european invasion - that is too recent. Why was such a successful farming system not still extensively in use when the europeans did invade?

I'll have to reread some of these links.

too tired tonight - I'll quote Mudd:

Dorme bien


I'm not sure what disturbed the system - it would be interesting to see how many samples have been carbon dated and if the results vary by location. Its not clear if the dates mentioned are the oldest samples or the most recent either (or if they all fit in the range mentioned).

The "1491" article I linked to is highly recommended - if you believe the theory described within, then European interaction (and the civilisational wipeout performed by European diseases) would presumably be to blame.


But we'd need to see a number of samples carbon dated to about 500 years ago (and none - or at least few - that are more recent) for that hypothesis to hold water...

Also, Carbon Dating doesn't give a precise date, due to the uncertainty in measuring small traces of radioactive Carbon. So "between 1780 and 2260 years" means that the oldest terrapreta that has been sampled is about 2020(+/-240) years old. It's not saying that the maintenance of terrapreta soils terminated 1780 years ago.

According to Michael J. Heckenberger et al (2008).
Pre-Columbian Urbanism, Anthropogenic Landscapes, and the Future of the Amazon.

Archeological records suggest the "urban" centers of Amazonia peaked between 1250 and 1650 A.D. Their undoing was the arrival of Europeans, who introduced diseases that may have killed 90 percent of the indigenous population upon first contact. In later centuries, warfare and enslavement at the hands of European settlers further diminished native populations. Their towns, villages, road networks, and elaborate plazas were reclaimed by the forest, leaving little trace of their existence.

What then disturbed the system?

Jerad Diamond has an idea in Guns, Germs and Steel.

Keep in mind that radio carbon dating has issues with more modern material due to the nature of the process. Other markers have been found (at least that is what my memory tells me) to help confirm the date(s)

Its great to talk in quality but no practical work can be done without knowing some quantity detail. A few questions:

How many kg of coal is needed per acre of poor soil?

How much time it takes to become terra petra?

How much carbon is captured per acre? Is it once only carbon capture or do it happen every year?

You mentioned that terra petra soil is rich, how much yield increase it give in crops as compare to the surrounding poor quality non terra petra soil?

Keep up the great work. Can't change habit of thinking in numbers :).

Its great to talk in quality

That is all that can be done on the internet is talk.

but no practical work can be done without knowing some quantity detail.

Bull. Practical work can be done on ones stove top. Or with a 5 lbs bag of charcoal.

Now, much is not known at this time, but this is why people are busy trying things with their soil. To learn.

A few questions:
How many kg of coal is needed per acre of poor soil?

Oh dear. One does not put COAL (which is a rock filled in many cases with nasty toxins) on soil.

How much time it takes to become terra petra?

It is terra preta the day you put the biochar into the soil. Not really good terra preta, but the 1st step in any journey occurs with the 1st step.

How much carbon is captured per acre? Is it once only carbon capture or do it happen every year?
You mentioned that terra petra soil is rich, how much yield increase it give in crops as compare to the surrounding poor quality non terra petra soil?

Read the links from this page. Each has a story to tell and you will obtain various answers to each of your questions. Choose the ones that make sense to you.

I love to see people working with nature rather than against it. These types of projects tend to fend off destructive technologies by making such clearly helpful additions to the planet and our understanding of it. I chuckle to see so many people of a scientific bent marveling over the wonderful insights of the ancients. They had it right all along. I can only hope people continue to listen in egoless appreciation.

Very good work, Big Gav.

Great to see this getting such attention. One problem is the fire used in turning the biomass to charcoal. I believe it would be possible to sufficiently concentrate sunlight to replace all or most of the heat from fire. The idea might be called solar hydrous pyrolysis. See wikipedia for the hydrous part.

Charcoal production can generate toxic waste if performed incorrectly.

That's not quite correct. Pyrolysis can produce toxic liquids even if performed correctly. It all depends on the feedstock used and the exact sort of process used.

In addition, if carbonization of biochar is done in a low tech way, then it usually leads to uncontrolled emissions, including tars which are highly toxic organic complexes. Do not try doing this at home!

The type of biomass and production conditions also have a major impact on the amount and composition of phytotoxic and potentially carcinogenic organic materials that are produced during pyrolysis (Lima A, Farrington J, and Reddy C. 2005. Combustion-derived polycyclic aromatic hydrocarbons in the environment: a review. Environ Forensics 6: 109–31)

Pyrolyzed oils and liquids can be carcinogenic and destructive to plant and animal life. You may like to take a look at the MSDS for pyrolyzed wood bio-oil

I hope this process will help combat GW, but we need the scientists to take the lead here. If they can determine a safe process and then implement it on an industrial scale, we may benefit. This is essentially a high-tech field of endeavour with great promise, but also significant dangers.

More reading: Biotox - toxicity and biodegradability of a representative bio-oil

Yes because all those thousands of years ago the charcoal makers of the amazon were scientists. I am scientifically trained and it is very simple to produce high quality biochar from using a TLUD gasifing stove which you can make out of metal cans. Check out http://www.youtube.com/lannyplans and http://www.youtube.com/agrisonic to see them in action. I made my own and use them to boil water each morning to go into a thermos for hot coffee all day. It burns up small twigs and off cuts and leaves perfect charcoal. (Perfect charcoal will have no smell and clinks.) Then the charcoal gets crushed and added to the garden along with worm castings and worm juice. Simple and cheap. I am currently working on scaling it up to deal with larger biomass.

There are many cases of primitive peoples doing things that were very dangerous to their health. The life expectancy of industrial workers in ancient Rome are currently unknown, but surely not high by modern standards. In 19th century Italy charcoal burning was an occupation that was known to be dangerous. Only the poorest were willing to engage in it. Life was definitely NOT a bowl of cherries. Maybe that situation will recur in the near future. But also maybe if you engage in certain behaviors, you deserve to have your health insurance canceled.

Any high temperature retort that is made out of metal cans is subject to gas leaks that develop over time due to corrosion and rusting. When the retort starts to leak
the operators start to breath poisonous gases.

If you are really concerned about it then I think you you start by stopping everybody from lighting any fires whatsover. Wood gas stoves are not very different to lighting a barbeque. All of the same gases are produced when you just have a fire. It is just that the majority are oxidised but tars, condensates, carbon monoxide, and nitrous oxides are still produced. Using gasifing stoves are far more efficient at burning wood and much cleaner as they double burn (pyrolyse the wood and burn the gas). As far as leakage is concerned you can tell when it is breaking down because they start to smoke or fire appears where it shouldn't. It is simple and safe. Philips is making a model that is being released in India. It is this sort of technology that will end up being used because it is low tech. High tech solutions will all run into major problems when the energy supplies and systems contract.

Crudedude, do you own due diligence. Properly, not via Youtube. I did, and I found scientists working in this area voicing concern over this issue. That's all I'll say.

I have done plenty of research of this subject even going as far as talking to Lukas who is in the Agrichar video above. The results speak for themselves. I boil water in the morning by burning kindling wood in a gasifying stove. It produces smoke for about a minute and then the rest of the burn is smokeless for the next 20 mins. I boil 4 litres of water and have five handfuls of charcoal leftover from the process. This gets crushed and eventually gets added to the garden along with compost and worm castings and juice. THe water goes into a large thermos to keep it hot all day.

So the end result is when I boil water to make all my cups of tea and coffee for the day and it is carbon negative. How do you mamba get your energy for coffee or tea? This process is simple and straight forward.

There is a large amount of concern over the condensates left over as to whether they are harmful or benefical to the soil organisms. Well if Paul Stamets work with fungi is anything to go by then it is a food source for fungi and probably bacteria too. The rule of thumb is to add it to compost heaps or worm farms to get the soil biota and nutrients into it.

Anyway while everyone is waiting for the big pyrolysis unit to come down to the farm and char all their biomass, I'll drink coffee each day and be sequestering carbon. Now imagine if all of us did this each morning instead of switching on the jug. That's all I'll say.

including tars which are highly toxic organic complexes.

These tars are the fuel for bacteria and plants.

The way to harvest these low-tech is to examine the 'wood gas for your car engine' material from the WWII era.

Do not try doing this at home!

Trying is how one learns. Better to know how to create a safe char now and to know what needs to be done material wise now than in the future the 'doomers' imagine.

Yes! Terra Preta!

One of my favorite odd subjects! Thank you for the article and thread!!

   I read the Nat. Geographic article when it came out and have been studying "soil life" (had never thought of it that way) and TP / bio-char and pyrolysis since learning about it all about a year ago. So many avenues, and possibilities. Carbon sequestration, fuel, heat, waste disposal (and of course, more waste).

   I also suspect the sometimes extended depth of the soil greatly enhances water retention, as well as the resilience of the microbial life-cycle within.

   As I posted above there are gardeners using charcoal in their soil already and having good results. Though I suspect that the soil being so old is part of what makes it so nutrient rich and hard to reproduce.... you need a few decades for it to evolve?

   I bought, and beat to shreds, a 40lb bag of natural charcoal the other week, to bury in the garden. - Calculated my Carbon footprint (CFP) to find that that 40lb bag compensates for only a day and half or so of my CFP! I'd need to spend about $15-25 a day to compensate for my existance! :D

Again, many thanks!

More links:


International Biochar Initiative:

There's a long informative comment after this article, lots of links:

Quite a few years ago I read an article about Justus Von Liebig, who is the most important scientist in the advancement of modern chemical fertilizer industry. Here is a link to the article.


As you can read, he realized the mistake to underestimate the role of carbon, but it was too late. Even today his error is ignored.

...Nitrate beds from Chile, potash mines from Germany and American phosphate deposits were sources for the initial N-P-K rush, but in a few short years chemical companies had begun to process and synthesise “the big three”. The profits in providing these new “essential” commodities, on a world stage, were stupendous. It was no surprise that, when a humbled von Leibig announced ten years later that he had made a huge mistake, his confession was completely ignored. Von Liebig had realised that a large part of the initial response to N-P-K fertilising was actually derived from the release of nutrients from the gradual breakdown of the humus component of the soil....

Whoa. Steady on.
Mamba up the thread has some good points on the science.
I am an (ex) agri scientist, and though my soil science is a while ago, a few points strike me.

The film I saw on TV of existing (still used) growing beds in Mayan territory (South America) showed essentially floating raised organic debris mats (beds), perhaps 2 or 3 meters thick. The human culture had created essentially a system for nutrient recycling (NPK + minor elements) supplemented or drained by the river.
There are several physical processes that hold nutrients in position in soil, and that help / degrade a soil's capacity to hold / lose nutrient ions from porous soil solution - cation exchange being very important. Some soils hold sequestered (unavailable to plant roots) large proportions of some of their mineral constituents - typically phosphates (hence the 'success' of inorganic soluble superphosphate, processed from mined rock phosphate from 19thC onwards}.
'Pretta' could be a useful additional medium for holding and / or mobilizing soil nutrients. If it also allowed some nitrogen-fixing soil bacteria to increase their N input, then that would be a bonus.
Whether there are bonuses to be had in other agricultural systems and in drier environments, ranging from cool temperate to dry tropics, remains for research to discover.
If a large proportion of nutrients in food are not recycled you will still need a 'primary' source of NPK. Clover and other legumes fix N from atmospheric N2, and soils often have reserves of P&K, if the latter can be made more labile, as in Western 'modern' (last 250 years) organic farming. (The fertilizer wars of the 19thC were mainly because organic agriculture production could not keep up with rapidly increasing urban populations.)
Do not confuse charcoal with humus.
Old, high-humus, pasture or mire or river-amended soils do provide a store of original nutrients and have been 'mined' historically until they become less fertile (think USA, Eastern England and etc). Their soil carbon has been oxidised gradually to CO2.
Big Gav, I see a typo, you say "Biochar is the term for what is left over after the energy is removed: a charcoal-based soil amendment - this process is called pyrolysis."
You mean 'some' of the energy is removed - like when coal was used to produce 'town gas', leaving coke.
Not a bad idea to sequester some long-life biomass 'coke', but 'success' depends on global numbers and whether we can afford turning over large areas to 'energy' biomass production.
best of luck
EDIT: if you burn wood for cooking on open fires or stoves, most (?) of the N is lost to the atmosphere but much of the P & K and trace elements are retained in the ash. The ash also contains a lot of 'charcoal' embers. I imagine this is what the Maya did. If they put the ash on their gardens, which they would do,being good gardeners, they were probably 'importing' P&K soil nutrients from the large surrounding areas of forests as well as accumulating gradually the 'pretta' in their soil.

A freind of mine works with Danny Day. He tends to emphasize that quite a lot can be learned about charcoal making from Japan, which had a number of technical programs during the war years whose liturature is worth translating. Anyone here who is good at reading technical books and papers in Japanese might be able to help out be contacting Danny Day's company that Big Gav linked above. You might have to help to write a grant though if you want to get payed.


Its not uncommon for Japanese organic growers to char rice husks and use them for soil improvement. They make a very light and friable soil. They are also sold for a pretty penny at hardware stores.

Great article by the way. I'm really looking forward to digging into the links.

I've been playing with terra preta for a number of years. First, here's a link to a post of mine about "Todd's Black Gold Method" from 2007 on TOD http://www.theoildrum.com/node/2410#comment-173726

My interest was first peaked because it appeared that tp held phosphorous which I saw as the one nutrient that I couldn't supply. Initially, I set up three beds with 0%, 2.5% and 5% charcoal (The charcoal was derived from mesquite barbeque charcoal that was so hard I had to run it through a chipper.) Since I couldn't afford a multitude of soil tests, my plan was to grow winter wheat in them since winter wheat won't head out without adequate phosphorous. So, the plan was to grow wheat on wheat until they stopped heading out.

After three years I had to stop it so I could rotate my potatoes to that bed since the bed they were in had wire worms.

But even in that short time I started to notice one difference; although head size didn't change, the wheat in the beds with charcoal was shorter depending upon the amount of charcoal. The 2.5% bed wheat was about 1-2" shorter while the wheat in the 5% bed was 3-4" shorter. The source of the N was calcium nitrate and the K was from green sand. No P was added.

In any case, I so believed in tp that I converted about 1,000 SF to tp. My charcoal comes from burning small slash piles from cutting firewood.

One side note is that I had discussed this with our county's deputy agricultural commissioner who is a friend. Last year his 6th grade daughter did a tp experiment for the county science fair. They used some charcoal I had given him and added it to soil along with fertilizer, with plain soil as a control. They then leached the test pots. They planted corn as the "crop." The results were that the corn in the tp pots grew far better.

I agree that there are a ton of unanswered questions. For example, does particle size matter? Does tp, indeed, hold nutrients? Does the temperature at which the charcoal is made matter? Is organic matter decomposed at a rapid rate (due to a more active rhizosphere)?

In any case, I'm a believer in terra preta. I still have another 1,000SF I'll be converting over the next few years.


interesting stuff.

I also deliberately create charcoal from yard waste. I look for reasons to BBQ or just have a beer by the fire pit, and tend to use a more robust fire than needed. Once the fuel is largely charcoal, I quench the fire with water, and eventually transfer the material to planting beds. (The pit is a 2 ft diameter slice of old propane tank and has held up well to the abuse).

I don't have a lot of mequite around, but I do have pine, eucalyptus and bamboo. Very different textures to the product in both piece size and hardness, and I have wondered if I should crush the charcoal or limit amounts of it added.

I look forward to reading more about all this.



I'm afraid I'm missing the implications of the shorter wheat with increased charcoal %. No apparent impact on head size, but shorter. Conclusion?

Could you describe your process of converting from as-is to tp?



I honestly don't know what the implications are of the shorter height.

That's the problem of not being able to do real ag research. I would need replicated beds, lots of soil tests, some measure of rhizosphere activity (which should probably also determine what species are present), objective yield measurements, several years of using a variety of crops, etc. along with all of the other unanswered questions. The best I can do is offer observational results.

You can get a pretty good idea of what I do by reading my old TOD post linked above. Here's a quick overview: I make small burn piles of slash (about 6x6x6' or 2x2x2meters). Most of the branches are less than 1" (2.54cm - to show that college education wasn't wasted). I rake out the hot coals, put them into a metal pail and break them up with a shovel and cover the pail until they stop burning.

I winter mulch my raised beds with a few inches of alfalfa hay (since you obviously can't cover crop) and the charcoal is placed on top of this - about an inch deep. Everything is turned over at spring planting and tilled with a Mantis tiller (This is a small front tine tiller) to break up the charcoal even more. It's my theory that fine material is better since more area is exposed - but that's another unanswered question.

FWIW, my plan for the beds I haven't converted is to continue cover cropping them. I used to use a fancy seed mix but it is too expensive so I'm switching to oats this year. I'll start to convert them during the winter of 2010. I'm assuming that the currently converted beds will have 2-5% charcoal after this year. These will actually be a better test since they are terraced into the hillside (I live in the mountains) whereas the beds I have converted are on a level area and are raised. The reason this will be a better test is that terraced beds always have poorer soil on the inside so I'll be able to compare this with the better soil on the outside. Does this make sense? This difference is well known in grape growing areas since inside and outside vines often produce significantly different wines.

Hope this helps.


Yes, interesting work.
Presumably you applied to your plots all the material left over after firing / pyrolysis?
Wood ash I know is a significant source of potash, but I do not know how much phosphate it might contain on average. (I remember when working using a radioactive tracer isotope P32, we all had to stop sending even slightly contaminated paper etc to the University incinerator because the poor man who removed the ash was found to be dealing with quite concentrated radioactivity!Not much was being driven off during burning.)I suspect that both these minerals are concentrated in your 'char', but if you have nice friendly contacts with your local agricultural service I guess an analysis would be pretty easy and low cost these days.
Perhaps yearly soil amendments could be a way of transferring significant P&K from woodland to soil? Could this be part of the 'secret'?

Aside from the useful comments on biochar by Big Gav, the statement "however soil is renewable, so any "peak" should be able to be reversed if sufficient time and effort is put into doing so" is a truism impossible to achieve. The time required for soil formation greatly exceeds any human relevance. It is possible to upgrade the growing ability of residue from soil loss, but soil is a nonrenewable resource and should be treated as such.

"The time required for soil formation greatly exceeds any human relevance. "
Not according to John Jeavons who has done a lot of work in this area. It's not a simple question since it depends on what you start with. I assume we mean starting with a very inferior soil and building it into high productivity. Starting from solid rock would take some time I grant.

I'm familiar with John and Common Ground, John's display garden in Willits, CA since I live north of it in the next town. John hauled in 35 tons of soil ammendments on an overhead cable system when the garden was started. Hardly an endorsement of a growing system that says compost, deep rooted plants and double digging does it all. In fact, a couple of years ago, the garden only could produce one meal a day for the people due to a lack of compost - read fertilizer.

I'm not trying to put down John or biointensive methods but rather that hype often hides reality.


I am somewhat familiar with John's work both in Palo Alto and Willits. The change in soil I saw was in Palo Alto. Taking a few isolated facts out of context isn't very convincing. What I personally did in Santa Cruz wasbased on John's work but was not directly comparable. Anyway, with limited daily time and using what was at hand it took me a little more than 4 years to transform the soil. Now I'm working with particularly challenging soil in Hawaii and I don't have time to develop in "naturally". I'm bringing in lots and lots of organic material, dolomite and gypsum. I'm aiming for sustainability in the long run by growing organic material on the land and correcting the mineral deficiencies with wood ash from wood grown on the land. One could look at what I'm doing right now and sneer at my "sustainability". I suspect that after years of work in Palo Alto, John was anxious to bring his Willits land into high production more quickly. So much for bringing in soil amendments (if your numbers are accurate which I somewhat doubt).
As to only producing "one meal a day for the people", how many people on what size garden? John is running a teaching operation and the number of people that only got one meal might reflect how many can be taught at his facility rather than a reasonable garden area to person ratio.
I had hoped my recent relocation from Santa Cruz would be to Willits and that I'd renew by acquaintance with John, but land is so much cheaper here (in the lot sizes I can personally handle) and the growing season so much longer, that I abandoned the mainland for the Big Island.


The numbers are accurate. I used to do certification inspections for the Mendocino County chapter of California Certified Organic Farmers and I did John's place once or twice. He gave me the numbers.


FWIW, David Montgomery is one of the 2008 MacArthur Fellows (the US$500K genius awards), is essentially a soil scientist ("geomorphologist" is a higher order label), and wrote the recent book Dirt: The erosion of civilizations.

An earlier book in the same vein is soil scientist Daniel Hillel's Out of the Earth: Civilization and the Life of the Soil and his recent text Soil in the Environment: Crucible of Terrestrial Life

As a carbon sequestration method, bio-char is not very efficient compared to carbon capture(+85% efficient). A million tons of coal with CCS would fuel a ~250 MW power plant and release up to 550,000 tons of CO2 to the atmosphere.

The typical bio-char method is pyrolysis to 'bio-oil'(60%),
hot gases(30%) which are vented after pre-drying the biomass and char(10%).

Bio-oil is NOT petroleum but a black highly acidic gummy goo; to usual approach is to turn it into low BTU synthesis gas. Still, bio-oil can be easily stored.

1 million tons of biomass could produce 100000 tons of biochar and furnish oil to fuel a 125 MW power station for a year. One ton of biomass normally produces 1.8 tons of CO2.

Therefore, a 125 MW bio-char plant would release 1,620,000 tons of carbon dioxide, but would be carbon negative ASSUMING there would be no change in land use.

It would take 40 square miles of high yield Brazilian(tropical) sugar cane to produce 1000000 tons of biomass. Non-tropical biomass will be much less productive.

An acre of terra preta holds 150
more tons of carbon per acre than normal soil which has 100 tons of carbon in it.
Therefore 100000 tons of biochar per year would be spread over up to 660 acres, square mile every year.

Terra preta would probably work best in tropical countries with bio-oil being exported
as a carbon cap and trade chip. But as such it would be a threat to the ecology of rainforests and other undeveloped areas.

A 1000000 tons of biomass might produce either
140000 toe of cellulosic ethanol(70 gal per ton currently) or 260000 toe of bio-oil(bio-oil has 40% of the energy of diesel and contains 25% water and ash). If the bio-oil is then gasified and reconstituted by Fischer Tropsch methods(50% efficient), the 260000 toe would be reduced to about 130000 of petroleum type products. It's hard to see that other technologies could use bio-oil much better.

The fertilizing power of bio-char/terra preta is rather speculative but it may fix a certain amount of nitrogen in tropical soils. I doubt it can fix enough to support the large amounts of nitrogen used in modern mass agriculture, IMO.

Or is there evidence otherwise?

For the BAU centralized commercial model such calculations as you present may be relevant. It was an article of faith among the enlightened Green community back in the 70s and 80s that centralized biomass was a disaster but the in decentralized situations it could be very effective depending on that situation. For a small operation on inadequate soil working towards sustainability agrichar looks very attractive.

Quoth majorian:

The typical bio-char method is pyrolysis to 'bio-oil'(60%)

That's incorrect.  Char is a (relatively small) byproduct of bio-oil production, but IIRC it is typically burned (along with the gas) to provide energy for the process.

The University of Hawaii and others have developed processes which produce primarily char and gas (relatively little oil/tar).  The pressurized downdraft pyrolizer linked in "Sustainability" produces about 30% of the original biomass weight as char.

Torrefaction is another possibility for processing raw biomass for storage and transport.  It reduces the dry mass by about 30% at a cost of about 10% of the embodied energy, and the product is relatively hydrophobic (won't take up water or rot).  I have no idea of the properties of torrefied biomass after further charring; it may not be as good a soil amendment as the product of other processes.

If the bio-oil is then gasified and reconstituted by Fischer Tropsch methods(50% efficient), the 260000 toe would be reduced to about 130000 of petroleum type products. It's hard to see that other technologies could use bio-oil much better.

Bio-oil probably is not the optimal intermediate form; other char-production schemes produce gas directly.  If e.g. a downdraft pyrolizer converts biomass energy to 50% char, 40% gas and 10% heat, 1 million tons biomass (@ 17.4 GJ/ton) would yield 8.7 million GJ char, 1.7 million GJ heat and 7.0 million GJ gas.  F-T conversion of the gas at 50% would yield 3.5 million GJ or about 570,000 BOE of hydrocarbons (6.1 GJ/bbl).  At 7.3 bbl/ton, this would be about 78,000 tons.  I'm not sure what conversion factors you are using, but your numbers look a bit off to me.

Soils are critical to the health of our planet and of course human survival. For a great read be sure to check "The Worst Hard Time".

My father remembers living in Colorado during the Dust Bowl, although many of the lessons learned were ignored. In the book a farmer mentions that where ever you are standing, all the separates you from Hell is the thin layer of A horizon soil. Without that thin layer you are utterly doomed.

Of course in understanding any scientific subject we stand on the shoulders of giants, Darwin was here.

Thanks for posting this.

There was one paper I saw a couple of months back, that reported on a counterintuitive net soil carbon loss, from a biochar experiment in Boreal Forest. (Note Boreal Forest is subarctic, think Canada/Russia, not prime farmland). Apparently the charcoal changed the soil ecology such that soil carbon was lost. I think the takeaway from this is that the benefit/damage from using biochar probably depends upons details of the local soil and climate, and perhaps on the details of the biochar process itself. I think this means that a lot of local research will be needed to determine the areas and crops for which the method is effective. My guess wrt carbon storage, is that we can probably absorb so small fraction of our current carbon emissions with this method, but I don't think it is a silver bullet. Just as in energy, it looks like their are no silver bullets, but all silver BBs should be pursued.

If atmospheric CO2 is captured as biomass, and converted to charcoal for sequestration about half of the carbon will return to the atmosphere during pyrolysis. This affects the efficiency of the capture process, but not the volume of charcoal that must be stored. The remaining carbon in charcoal could be compressed prior to storage to a density approximating the density of coal. The storage space needed to contain the carbon that we have released into the atmosphere is approximately equal to the volume of coal that has been mined since the start of the industrial revolution. This is a large volume. But it can be determined from the historical record. We have already moved all that carbon once in moving from mine to market. We can move it again. And maybe we don't have to capture ALL of it to control global climate change. Maybe half or less is good enough.

While capturing carbon for climate control we can tap the system for a source of charcoal to create terra preta. The residence time of carbon in terra preta is long. Using some charcoal to improve soils will not seriously degrade the capture/sequester system of climate control, and could do some environmental good. But I wonder if the world needs all the terra preta that would be produced if ALL the carbon were to be directed into terra preta production.

The study was in a forested area that already had a very healthy layer of peat. This means that there was already a lot of carbon in the soils. Essentially, it doesn't help much to add more carbon to soils past some point.

Given the current state of global soils. Nearly all could benefit.

Hello TODers,

The US military command, AFRICOM, goes fully operational in October. Who knows what the future holds, but, IMO, Morocco's P is incredibly strategic at 47% of the total current global flowrate.

I really hope huge, Global progress can be made with TP,Biochar in the postPeak years ahead.

Bob Shaw in Phx,Az Are Humans Smarter than Yeast?

Hi Bob!
I appreciate what you are saying but I'm not very optimistic about "global progress" as compared to "local progress". I hear you about PNK but how does this apply to me? I need Ca and Mg fast on my thin rain soaked volcanic soil. (And P and N and K and ..but in amounts I can provide organically..). When the ag extension analysis for my soil came back they included prices for the dolomite, gypsum and PNK they thought I should use. Though the prices were probably out of date, I found in curious that all 3 were about the same on a per pound basis. Did this mean that the cost of the material itself was not significant compared the cost of shipping?

When I think of our current agriculture I get the idea of immense quantities of PNK, moving in ships around the globe, being spread on the land to be washed out to sea. Can this be sustained? Should we even try?

It is wishful thinking to believe that biochar is self-regenerating. Also, ascribing regeneration to mycorrhizae is unreasonable. Mycorrhizae do not perform pyrolysis. Rather, they consume plant carbohydrates for energy. Mycorrhhizae are heterotrophic and would not be in the business of intensive energy waste, by excreting reduced carbon.

The persistence of carbon char in Amazon basin soils is favored by anoxic and acidic conditions.

While charcoal itself is persistent, it speeds the decomposition of more fragile organic materials that are also present.


In boreal forests.

No one appears to be claiming that this happens elsewhere...

Why shouldn't it happen elsewhere?

The effect should be universal.

Activated carbon is famously known to adsorb organic molecules and catalyze reactions.

This Bio-char is a specific co-incidence to a specific regional problem.

Soil Microbes are the gods we want in soil, not charcoal. Bacteria and Fungi average a 30;1 Carbon/Nitrogen ratio. Soils with no carbons for their nitrogens, have no microbes and are DEAD.

Charcoal does the things mentioned in the article but if it is not making microbes it is useless.

The Micorizha are but a few of the 53,000 (plus or minus a few)different species of microbes a soil needs to be healthy.

There are far cheaper and better ways to achieve healthy productive soils than doing it the bio-char way, which was actually an historical accident which turned out to be beneficial.


There are far cheaper and better ways to achieve healthy productive soils than doing it the bio-char way,

Please provide links to illustrate these ways.

The char's enormous surface area is very beneficial to the microbes and allows more per unit of soil. Please describe how to do even better than biochar for less effort.

There are far cheaper and better ways to achieve healthy productive soils than doing it the bio-char way,

Do post links.

It is wishful thinking to believe that biochar is self-regenerating.

A higher cost of oil does not make more oil in the ground.

And biochar is not self-regenerating per-say. The rate of fires on the land shows this.

The claim however is that Terra Preta DOES regenerate.

biochar != Terra Preta but without the 1st step of biochar it is hard to get terra preta.

Also, ascribing regeneration to mycorrhizae is unreasonable.Why shouldn't it happen elsewhere?
The effect should be universal.

You do realize that fungi grows in different places and does different things at different temperatures and soil chemistries right?

Thus, effects are not 'universal'.

There are no scientific bases for claims that Terra Preta regenerates itself.

There are no scientific bases for claims that mycorrhizae are involved in elemental carbon production.
Changing pH, moisture, temperature, soil food web species, etc... does not open biochemical pathways to produce elemental carbon. Such pathways have not been shown to exist.

Carbon is produced by thermal processes sufficient to break carbon bonds to other atoms, not through biochemistry.

I will be appropriately sheepish if shown to be wrong, but I doubt that it will come to that.

Let’s try this again. My response above to Eric confuses rather than clarifies why I refute two separate claims as false.

Claim 1.) That Terra Preta regenerates itself

There are no controlled (i.e. reputable) studies that demonstrate chemical or physical processes to manufacture elemental carbon under ambient conditions such as in soils. Extraordinary claims demand extraordinary evidence.

Claim 2.) The report in Science magazine, which found that humus mixed with charcoal loses mass faster than either humus or charcoal alone, is not universal

While no ambient processes create carbon, there are plenty of biochemical and physical processes that destroy organic materials, in a Boreal forest or otherwise. Some of these processes would reasonably be accelerated in the presence of an inert high surface area material such as char (i.e. by harboring heterotrophic microbes, having high adsorptive capacity for molecules, heterogeneous catalytic properties, etc.). By contrast, no one has posited any specific reasons why char (free of toxic residues and also having an oxidized surface) should not accelerate humus decomposition in any soil.

Carbon to the Soil is the only ubiquitous and economic place to put it.

Total CO2 Equivalence:
Once a commercial bagged soil amendment product, every suburban household can do it,
The label can tell them of their contribution, a 40# bag = 150# CO2 = 160 bags / year to cover my personal CO2 emissions. ( 20,000 #/yr , 1/2 Average )

But that is just the Carbon!
I have yet to find a total CO2 equivalent number taking consideration against some average field N2O & CH4 emissions. The New Zealand work shows 10X reductions.

This ACS study implicates soil structure as main connection to N2O soil emissions;

biochar papers at the ACS Huston meeting see Ron Larson's post http://tech.groups.yahoo.com/group/biochar/message/1852

Biochar Studies at ACS Huston meeting;

578-I: http://a-c-s.confex.com/crops/2008am/webprogram/Session4231.html

579-II http://a-c-s.confex.com/crops/2008am/webprogram/Session4496.html

665 - III. http://a-c-s.confex.com/crops/2008am/webprogram/Session4497.html

666-IV http://a-c-s.confex.com/crops/2008am/webprogram/Session4498.html

Most all this work corroborates char soil dynamics we have seen so far . The soil GHG emissions work showing increased CO2 , also speculates that this CO2 has to get through the hungry plants above before becoming a GHG.
The SOM, MYC& Microbes, N2O (soil structure), CH4 , nutrient holding , Nitrogen shock, humic compound conditioning, absorbing of herbicides all pretty much what we expected to hear.

The Terra Preta Prayer

Our Carbon who art in heaven,
Hallowed be thy name
By kingdom come, thy will be done, IN the Earth to make it Heaven.
It will give us each day our daily bread and forgive us our atmospheric trespasses
As we forgive those who trespass against the Kyoto protocols
And lead us not into fossil fuel temptation, but diliver us from it's evil
low as we walk through the valley of the shadow of Global Warming,
I will feel no evil, your Bio-fuels and fertile microbes will comfort me,
For thine is the fungal kingdom,
and the microbe power,
and the Sequestration Glory,
For ever and ever (well at least 2000 years)

There are no controlled (i.e. reputable) studies that demonstrate chemical or physical processes to manufacture elemental carbon under ambient conditions such as in soils.

That is because to 'manufacture' elemental carbon you need the heat and pressure of a solar body.

The claims are over years and controlled observation has only just begun.

But hey, you just keep making claims that are 'correct' because soil doesn't char itself and elemental carbon isn't "created" in soils as such a creation method needs to be forged in a solar body.

When you can quote Elaine Ingram - you'll have something to be considered. Otherwise you are 3 for 3 on the 'biochar' claim, the 'fungi don't grow the same in warm VS colder places' and 'the element of carbon isn't made in soil' observation leads me to consider you to be non-authorative.

Your ad-hominem screeds do not advance your case.

Here's mine: "Terra preta self-regeneration is the equivalent of cold fusion for the clueless tree hugger."


They don't exist, just like there are no non-fanciful accounts of antigravity boots or time machines.

The self-regeneration claim implies not only that carbon is produced in soils, but that carbon present apparently "primes" new production. Carbon has been studied far more than any other element, and in the vast literature you will find nothing to support your belief.

Now, I am done arguing with a flat-earther.

Settle down - you don't seem to be listening to what he is saying.

No one is claiming that terra preta manufactures carbon (as far as I'm aware).

However, carbon can be added to soil by natural processes (otherwise we wouldn't have any soil and we wouldn't be here to have this conversation).

So presumably the terra preta advocates are hypothesising that the soil has some process taking place within it that extracts carbon from the atmosphere.

This may or may not be true, but it certainly doesn't sound impossible on the face of it.

If trees can do it, why can't some combination of microbes in the soil do it ?

The only known process in nature for fixing carbon from the air (other than carbonate deposition) is photosynthesis, and it is not elemental carbon being fixed.

The organic structures of soil carbons derived from photosynthesis directly or indirectly are, at best, poor facsimiles of the structures in char.

The only microbes known to fix carbon from the atmosphere are those doing photosynthesis such as cyanobacteria. Such organisms are only effective in sunlight, not beneath the soil surface.

All of the remainder of soil life-forms are net consumers of carbon.

In the video accompanying this post, in the segment where the cattle farm experiments Australia are described, the narrator contradicts himself. He states that agrichar increases soil respiration (i.e. increases loss of CO2), which makes perfect sense to me. However, it is later stated that the guy collecting gases in the fields finds less CO2 given off from the soil???

Agrichar may reasonably increase agricultural productivity by boosting soil respiration and in turn, nutrient flux. However, it is clearly a boondoggle in terms of carbon sequestration.

However, it is clearly a boondoggle in terms of carbon sequestration.

Really? So you say.

Lets de-construct what you have to say VS what others have had to say.

Some of the charred carbon in the soil is estimated to be over 1000 years old, which means it has not been consumed.

That carbon is typically the result of CO2 being processed from the air by plants into cell walls. Thusly removed out of the air at some point and it has stayed out of the air for over 1000 years.

You claim 'a boondoggle'. Fine. Show the rate of change of C in the soil to justify your position.

Because the 'we can put carbon from the air into the soil and it can stay there for 100's of years' position has carbon dating datapoints of the 1000+ year old char.

(Hilberts work back in 1968 as an example or Sombrock in 1966)

However, it is clearly a boondoggle in terms of carbon sequestration.

Really? So you say.

Lets de-construct what you have to say VS what others have had to say.

Some of the charred carbon in the soil is estimated to be over 1000 years old, which means it has not been consumed.

That carbon is typically the result of CO2 being processed from the air by plants into cell walls. Thusly removed out of the air at some point and it has stayed out of the air for over 1000 years.

You claim 'a boondoggle'. Fine. Show the rate of change of C in the soil to justify your position.

Because the 'we can put carbon from the air into the soil and it can stay there for 100's of years' position has carbon dating datapoints of the 1000+ year old char.

(Hilberts work back in 1968 as an example or Sombrock in 1966)

And I'll cite a mention of Dr. Ingham

Natural Black Soils, of the nature referred to by Dr. Ingham, may have
their "black carbon" in a form where it can be consumed by soil
microbes, while black carbon from charcoal does not seem to be
consumable by microbes for some several thousands of years. If this was
the case, then the black soils produced from charcoal would have the
advantage of increasing the CEC, for improved growth, BUT the single
treatment could be counted on to last for a very long time. Natural
carbon soils are known to get consumed over time by some combination of
oxidation as a result of tilling, and consumption by soil microbes.A lot
of field testing will be required to address these valid concerns. It
seems we should distinguish between natural black carbon soils, and
black carbon Anthrosols made using pulverized biomass char from pyrolysis.

Further deconstuction:

Some poster on TOD VS:

Amazonian Dark Earths have high carbon contents of up to 150 g C/kg soil in comparison to the surrounding soils with 20-30 g C/kg soil (Sombroek, 1966; Smith, 1980; Kern and Kämpf, 1989; Sombroek et al., 1993; Woods and McCann, 1999; Glaser et al., 2000). Additionally, the horizons which are enriched in organic matter, are not only 10-20cm deep as in surrounding soils, but may be as deep as 1-2m (average values probably around 40-50cm)! Therefore, the total carbon stored in these soils can be one order of magnitude higher than in adjacent soils.

Boondoggle or documented difference? I cite and let others handwave so you can decide.

Rated you up.

One thing I've not seen anyone mention yet:  biochar captures nutrient ions and prevents them from leaching out of soils, providing a store of nutrients other than the biota itself (tropical soils are very poor in nutrients).  This not only preserves the fertility of tropical soils, but could help reduce the required fertilizer inputs in temperate-zone cropland and reduce problems with e.g. dead zones in the oceans from nitrate runoff.

No one is claiming that terra preta manufactures carbon

Yet that is his claim.

What has been said is Terra Preta will 'regenerate'


Yet terra preta may have a still more remarkable ability. Almost as if alive, it appears to reproduce. Bill Woods has met local farmers who mine the soil commercially. They find that, as long as 20cm of terra preta is left undisturbed, the bed will regenerate over a period of about 20 years. He suspects that a combination of bacteria and fungi is causing this effect.

So presumably the terra preta advocates are hypothesising that the soil has some process taking place within it that extracts carbon from the atmosphere.

I can point to a possible vector - the symbiosis between fungi and plants not to mention the roots of the dead plants themselves. That should increase the carbon in the soil ESP if one is creating harder to break down carbon in the form of char and adding that to the soil. For the (proposed) test work with a university I'll be using long-standing Jeuslerum Artichokes (2 foot roots), Alfalia (20 foot roots) and yearly millet (4 feet + more char can be added to soil VS top applied) to test for water holding, changes in the 'darkness' of the soil (All sand ATM) and plant health. We can get oil stained rock dust (clay) from a roadway making plant nearby.

To say the claim of the BBC programs' claim is not proven is correct. But to handwave about 'elemental carbon' or 'should be the same everywhere' or the other bogus claims isn't correct.

I can point to a possible vector - the symbiosis between fungi and plants not to mention the roots of the dead plants themselves.

That's what I'd be guessing too - I don't understand why the idea that soil traps carbon is such a hard one to come to terms with (even if it may or may not be proven).

Living plants exude carbon compounds through their roots to feed soil life.

A portion of the carbon is lost back to the atmosphere through respiration by soil life, a portion is retained.

The carbon builds up in the soil, not from the atmosphere directly, but indirectly from plants.


(Unless of course you are seeking public funding for your terra preta study).

The carbon builds up in the soil, not from the atmosphere directly, but indirectly from plants.

That's exactly what Eric and I just said.

But you are too busy being argumentative and not listening to what we are saying.

As for your ridiculous jibe about seeking funding for a terra preta study, why don't you have a look at my history of posts and see how much attention I've paid to this subject vs others.

Then you can retract your idiot slur.

The oil drum is a great website, thanks in large measure to your contributions.


Amazing how I can provide citations and you provide hand waving.

(Unless of course you are seeking public funding for your terra preta study).

Again, I have provided citations http://anz.theoildrum.com/node/4522/416174
You have not.

As we all agree soils trap carbon through soil life sustained by plant carbon.

Setting aside biochar, which is not a living material, and thus may play a secondary role in carbon deposition and cycling, microbial-plant interactions are the more interesting due to their dynamic complexity.

Based on her expertise Elaine Ingham has some interesting things to say about the soil food web, but to be fair, as she is running a consulting business, so much of her writings are rather circumlocutory or cagey. Also, she is not as involved in research these days as she once was.

The recent scientific literature is a better source of info. There are many excellent papers coming out almost daily regarding the specific chemical interactions that operate among plants and soil life, regarding nutrient and carbon cycling.

Two authors I learned from are Michael Bonkowski and Donald A. Phillips.

As regards mycorrhiza, the 2 or 3 papers published in Science during the last year or so regarding species types and their chemical actions are groundbreaking (so to speak).

Normally in a debate one says 'gee I was wrong'.

Ya might wanna try that next time.

And my advice for you is to read more widely.

There have been several letters to the editor of Science published that comment on this publication. In brief, the conclusions are questioned by people who have enough rep. to get their letters published in Science. Now is not the time to extrapolate the results of this study to other climatic conditions. As a famous author has said, Cool It.

The whole concept of sustainability seems to have come down to this: the pitting our twin champions of technology and science in a foot race against our own flawed human nature. The latter induces us to defile our environment while simultaneously out-populating the capacity of remaining resources to meet our needs.

In my view, unless we control our population all the feel good ideas and hopeful breakthroughs such as this one will, in the end, not be enough to save us. It's like a new, Malthusian version of the "Tortoise and the Hare" allegory. In this version, the tortoise still wins but because the hare is busy giving birth to its own extinction.

I suspect the hope is that every country will eventually pass through the demographic transition to a stable global population before that occurs.