Bodemkoolstof – biochar – Terra Preta – zwarte aarde syllabus


Terra Preta / Zwarte Aarde

door Catharina de Bruin en Henk Ploeger

Syllabus samengesteld voor de presentatie tijdens de landelijke Transitie Conferentie

van zondag 2 oktober 2011 te Deventer

Door zelf Terra Preta te maken kan je CO2 reduceren en vruchtbare aarde maken. Opgedragen aan de heling van Moeder Aarde.


* De geschiedenis van Terra Preta: terug naar de oudheid

* Wat is Terra Preta?

* Terra Preta als bodemverbeteraar:

* Hoe Terra Preta CO2 reduceert en klimaatverandering tegengaat

* Hoe Terra Preta CO2 reduceert en werkt als bodemverbeteraar

* De koolstofchemie van Terra Preta

* Is er verschil tussen steenkool en houtskool?

* Wat doet houtskool in de bodem?

* Zwarte Aarde in Nederland

* Zelf Terra Preta maken

* Recepten en de samenstelling van Terra Preta

* Ramona’s recipe for home-made dirt (Terra Preta Soil):

* Meer info?


* De geschiedenis van Terra Preta: terug naar de oudheid

Biochar production is modelled after a process begun thousands of years ago in the Amazon Basin, where islands of rich, fertile soils called terra preta (“dark earth”) were created by indigenous people. Anthropologists speculate that cooking fires and kitchen middens along with deliberate placing of charcoal in soil resulted in soils with high fertility and carbon content, often containing shards of broken pottery. These soils continue to “hold” carbon today and remain so nutrient rich that they have been dug up and sold as potting soil in Brazilian markets.

Terra Preta: A 2000 Year Old Soil Experiment

(Steiner, 2002)

• Man-Made Soil Plots

• Average size 20 ha

• Carbon dated at 800 B.C-500 A.D

• High Carbon Content (9%)

• Local farmers prize terra preta which yields as much as three fold crop yields as

surrounding infertile tropical soils.



Terra Preta oogst in Brazilie; wordt verkocht als potgrond!

* Wat is Terra Preta?

Biochar Is a Valuable Soil Amendment

Biochar is a 2,000 year-old practice that converts agricultural waste into a soil enhancer that can hold carbon, boost food security and discourage deforestation. The process creates a fine-grained, highly porous charcoal that helps soils retain nutrients and water.

Biochar is found in soils around the world as a result of vegetation fires and historic soil management practices. Intensive study of biochar-rich dark earths in the Amazon (terra preta), has led to a wider appreciation of biochar’s unique properties as a soil enhancer.

Biochar can be an important tool to increase food security and cropland diversity in areas with severely depleted soils, scarce organic resources, and inadequate water and chemical fertilizer supplies.

Biochar also improves water quality and quantity by increasing soil retention of nutrients and agrochemicals for plant and crop utilization. More nutrients stay in the soil instead of leaching into groundwater and causing pollution.

Biochar is a Powerfully Simple Tool to Combat Climate Change

The carbon in biochar resists degradation and can hold carbon in soils for hundreds to thousands of years. Biochar is produced through pyrolysis or gasification — processes that heat biomass in the absence (or under reduction) of oxygen.

In addition to creating a soil enhancer, sustainable biochar practices can produce oil and gas byproducts that can be used as fuel, providing clean, renewable energy. When the biochar is buried in the ground as a soil enhancer, the system can become “carbon negative.”

Biochar and bioenergy co-production can help combat global climate change by displacing fossil fuel use and by sequestering carbon in stable soil carbon pools. It may also reduce emissions of nitrous oxide.

We can use this simple, yet powerful, technology to store 2.2 gigatons of carbon annually by 2050. It’s one of the few technologies that is relatively inexpensive, widely applicable, and quickly scalable. We really can’t afford not to pursue it.


* Terra Preta als bodemverbeteraar:

Biochar enhances soils. By converting agricultural waste into a powerful soil enhancer that holds carbon and makes soils more fertile, we can boost food security, discourage deforestation and preserve cropland diversity. Research is now confirming benefits that include:

  • Reduced leaching of nitrogen into ground water

  • Possible reduced emissions of nitrous oxide

  • Increased cation-exchange capacity resulting in improved soil fertility

  • Moderating of soil acidity

  • Increased water retention

  • Increased number of beneficial soil microbes

Biochar can improve almost any soil. Areas with low rainfall or utrient-poor soils will most likely see the largest impact from addition of biochar.

IBI has created two sets of guidelines regarding biochar and soils:

There are a number of publications on biochar and its effect on specific soil types in specific conditions. For more information on these topics, you can search the IBI Biochar Bibliography.

Biochar and Terra Preta Soils

Biochar production is modeled after a process begun thousands of years ago in the Amazon Basin, where islands of rich, fertile soils called terra preta (“dark earth”) were  created by indigenous people. Anthropologists speculate that cooking fires and kitchen middens along with deliberate placing of charcoal in soil resulted in soils with high fertility and carbon content, often containing shards of broken pottery. These soils continue to “hold” carbon today and remain so nutrient rich that they have been dug up and sold as potting soil in Brazilian markets.

Rural and Developing Country Applications of Biochar Systems

Biochar systems can reverse soil degradation and create sustainable food and fuel production in areas with severely depleted soils, scarce organic resources, and inadequate water and chemical fertilizer supplies. By making croplands more fertile for longer periods of time, biochar discourages deforestation. Low-cost, small-scale biochar production units can produce biochar to build garden, agricultural and forest productivity, and provide thermal energy for cooking and drying grain. With the addition of an engine or turbine, these systems can produce kinetic energy for grinding grain or making electricity. Click here for more information specific to biochar projects in developing and emerging economies.

(Upper photos courtesy of Julie Major and Bruno Glaser; lower photo courtesy of Julie Major.)

* Hoe Terra Preta CO2 reduceert en klimaatverandering tegengaat



If you could continually turn a lot of organic material into biochar, you could, over time, reverse the history of the last two hundred years…We can, literally, start sucking some of the carbon that our predecessors have poured into the atmosphere down through our weeds and stalks and stick it back in the ground. We can run the movie backward. We can unmine some of the coal, undrill some of the oil. We can take at least pieces of the Earth and – this is something we haven’t done for quite a while – leave them Better Than We Found Them.”
Bill McKibben

Bill McKibben, author, climate activist and founder of
Photo: Nancie Battaglia

How Can Biochar Be Carbon-Negative?

Fossil fuels are carbon-positive — they add more carbon to the air. Ordinary biomass fuels are carbon neutral — the carbon captured in the biomass by photosynthesis would have eventually returned to the atmosphere through natural processes — burning plants for energy just speeds it up. Sustainable biochar systems can be carbon negative because they hold a substantial portion of the carbon in soil. The result is a net reduction of carbon dioxide in the atmosphere, as illustrated below.

Biochar can hold carbon in the soil for hundreds and even thousands of years. Biochar also improves soil fertility, stimulating plant growth, which then consumes more CO2 in a feedback effect. And the energy generated as part of biochar production can displace carbonpositive energy from fossil fuels. Additional effects from adding biochar to soil can further reduce greenhouse gas emissions and enhance carbon storage in soil.

These include:

  • Biochar reduces the need for fertilizer, resulting in reduced emissions from fertilizer production.

  • Biochar increases soil microbial life, resulting in more carbon storage in soil.

  • Because biochar retains nitrogen, emissions of nitrous oxide (a potent greenhouse gas) may be reduced.

  • Turning agricultural waste into biochar reduces methane (another potent greenhouse gas) generated by the natural decomposition of the waste.

Diagram courtesy of Nature Publishing Group

How Much Carbon Can Biochar Remove from the Atmosphere?

IBI has developed a simple model to predict the carbon removing power of sustainable biochar systems. The figures here show the results of this preliminary model. We expect these answers will change as more is learned about the impacts of biochar, but the model gives a sense of what is possible.

The top figure on the right shows several scenarios that assume biochar production from waste biomass only, which is a small fraction of Earth’s annual net primary production (NPP). Counting only the impacts of biochar burial in soil, and without considering the displacement of energy from fossil fuels, we can conservatively offset one quarter of a gigaton of carbon annually by 2030.

Optimistically, we could achieve one gigaton of offsets annually before 2050.

In the “Optimistic Plus” scenario, we account for reductions in nitrous oxide emissions and for the feedback effect of increased biochar production that may arise from increased plant growth in soils enhanced with biochar.

The second figure highlights additional carbon offsets possible if energy from biochar production displaces fossil fuel energy, and if CCS (carbon capture and storage) is used.

* Hoe Terra Preta CO2 reduceert en werkt als bodemverbeteraar

De vruchtbare bovengrond wordt gevormd door groepje van slib, klei en zanddeeltjes die de koolstof vasthouden.


 Aggregates silt, sand and clay increasing water and air holding capacity, resulting in increased biomass yields.

” The structures are biologically built cathedrals, with large internal volumes

” They store compounds from decaying organic matter, multiplying their carbon storage potential


De grond heeft door de toevoeging van het houtskool meer capaciteit om water en lucht vast te houden, wat resulteert in een verhoogde opbrengst.

 “De structuren zijn biologisch gebouwde kathedralen met grote interne volumes “

Charcoal additions to A. mangium Seedlings

Height and diameter significantly increased at age of 6 months

 A.  0%                    B  10%                  C  15%               D  20%


Siregar, (2004 Indonesia), Forest and Nature Conservation Research and Development Center

* De koolstofchemie van Terra Preta


Terra Preta bevat maximaal 10% koolstof in de vorm van houtskool. Ter vergelijking: 5 gram Norit heeft een effectief oppervlak ter grootte van een voetbalveld.



Animatie van een bedrijf die biochar maakt.

* Is er verschil tussen steenkool en houtskool?

houtskool door pyrolyse van hout



                    koolstofskelet van het hout


Microscopische foto van houtskool. Z’n grote porositeit, de kleine gaten zijn ongeveer 1/100 mm in diameter, maken het een ideale plek voor opslag van water, voedingsstoffen en micro-organismen.

* Wat doet houtskool in de bodem?

Houtskool heeft door zijn structuur honderden, zo niet duizenden,   positief en negatief geladen plekken die andere atomen kunnen aantrekken en vasthouden. Dit heet Adsorptie.


Houtskool kan zowel positief als negatief geladen voedingzouten (ionen) uit de bodem aantrekken en vasthouden, waardoor de uitspoeling naar het grondwater en emissie van gas (ammoniak) minimaal is. Door de losse binding zorgt de houtskool voor een opslag en beschikbaarheid van voedingszouten in de bodem bij de wortelzone van de plant.

* Zwarte Aarde in Nederland

 Onze landbouwmachines worden steeds zwaarder, ze ploegen steeds dieper in de aarde. Het bodemleven wordt steeds minder. Vroeger zag je op oude filmbeelden nog zwermen vogels achter de tractor vliegen omdat de vogels profiteerden van een omgeploegde zwarte aarde vol bodemleven. Om mee te doen aan de economische groei werd het noodzakelijk om de landbouwgrond steeds efficiënter te benutten.

 Bron: film A farm for the future.

Aanbevolen literatuur: Energie voorbij piekolie / Rudy Dhont  op

Overigens werden de Terra-preta velden door de Nederlandse wetenschapper Wim
Sombroek in 1950 ontdekt.

Vandaag de dag worden de mineralen voor kunstmest schaarser op de wereldmarkt. Tegelijkertijd worden voor de productie van potgrond natuurgebieden in de Baltische staten afgegraven om te worden verkocht in Nederlandse tuincentra. Bekijk hier de uitzending over potgrond:

Terra Preta is hét antwoord om in je eigen omgeving op kleine schaal met kleine kringlopen de bodem te verbeteren en zelf CO2 te reduceren.


* Zelf Terra Preta maken


Engelstalige handleiding Terra Preta brander die houtskool maakt

The Terra Preta Stove

The simplest Woodgasstove,

providing charcoal for your Terra Preta

Ole Blente, Ökodorf Sieben Linden 2010

-1 The Terra Preta Stove. The simplest Woodgasstove, providing charcoal for your Terra Preta




Why this text………………………………………………………………………………………………….2

The quest……………………………………………………………………………………………………….2

How it works…………………………………………………………………………………………………..3

How it looks……………………………………………………………………………………………………4

In practise………………………………………………………………………………………………………7

How to build the simplest Terra Preta stove…………………………………………………..8

About size……………………………………………………………………………………………………….8

Choice of material……………………………………………………………………………………………8

Building instructions………………………………………………………………………………………..8

Why this text

Most people on earth are cooking and heating with some sort of wood or other plantmaterial. Mostly the woodgases are not taken care of. Instead of giving their wonderful heat, the poisonous gases are drifting away with half of the energy. Some big modern stoves though – often used in central heating systems – are

utilising the gases efficiently. For the crowds all over the world there isn´t any solution in sight.


The quest

Therefore it would be adequate to search for following:

• Materials to be found everywhere

• Tools as well

• Simple to build

• Simple to use


Well, some already thought of these questions and have been working on the matter for years. Some few could be mentioned:



Both companies have been doing urgent research and developing and have been crucial for the this project. Building on their experiences the clean burning woodgasstove was stripped of any details, which could distract or even prevent you from building it: What is left is an stove made of scrap – eg two cans – with the help of one tool, a knife, which, with the help of this simple manual, can be made by anybody everywhere.

– 2 The Terra Preta Stove. The simplest Woodgasstove, providing charcoal for your Terra Preta

How it works

Anything, that could burn is introduced into the burning chamber and ignited from above. This will produce smoke. (The gray arrows at the top). This smoke will contain water moisture and woodgas.

The low-temperature fire in the burning chamber will heat the air between the two tubes. After some minutes this air is so hot, (red arrows) that they are able to ignite the gases (upper yellow arrows). Now a clean smokefree flame will rise high over the stove.


Fresh air is heated and ignites the woodgas at the top of the stove.

– 3 The Terra Preta Stove. The simplest Woodgasstove, providing charcoal for your Terra Preta

When all gas is burned, the flames will perish. Now the charcoal will start burning and become ash returning wonderful, smoke free warmth. When the cooking finished is, this is the moment to pour water or earth on the charcoal in order to cool them down and keep them.

This stove will give you heat from the gases, you never used, and leave you the charcoal for free, so to speak. And why should you care? You don´t need to. Just put the charcoal in your compost. This enriches the earth, which will nourish your plants in a harmonious way, because it stabilises water and nutrients. The charcoal will help you build sustainable black earth. Read more about black earth

– Terra Preta – here:

How it looks

Here is a stove with some chopped of wood filled in. The burning chamber has a Ø = 18 cm. You can see, that the stove is situated on three bolts, found on the scrapheap, in order to create the air intake beneath.



Fire is ignited.

– 4 The Terra Preta Stove. The simplest Woodgasstove, providing charcoal for your Terra Preta


… and the stove is assembled.

Within some few minutes the flame will rise out of the stove. And smoke. As the secondary air gets hotter, the gases will start igniting inregulary and slowly stabilise. The initiating smoke development is difficult to prevent and makes the stove more suited for outdoor.

But with a fan it is possible:

– 5 The Terra Preta Stove. The simplest Woodgasstove, providing charcoal for your Terra Preta

For thousands of years we paid attention to the flames in order to cook our food. When dinner was ready, the focus changed. With the people satisfied, the fire was left on its own and next time you visited the fireplace, you found no charcoal, only ashes. So here is the crucial point:  When the gasses burn out and the flames disappear, …


… it is time to harvest charcoal.


The stove can be refilled during burning. This might lead to creation of ashes, though.

When refilling small amounts you might experience smoke development during the cooling phase, because the latest refilled material still produce gas. This final smoke development might be reduced if you care to refill more and not so often.

– 6  The Terra Preta Stove. The simplest Woodgasstove, providing charcoal for your Terra Preta

In practise                                                           

Here are a few pictures from our experiments at the EDE-course 2010 in Ökodorf Sieben Linden. The emphasis was rather on building the stove than the kit for cooking.

To the right the previously shown stove used to make pancakes. For this purpose the stove had to be refilled often. As you can see, it is situated on bricks, which lets you control the air intake.

To the left is a picture of a bigger stove. Fuled with bigger lumbs this stove provides gas for a meal. Some smoke developement is visible due to a too big space between the inner and the outer tin can.


 – 7 The Terra Preta Stove. The simplest Woodgasstove, providing charcoal for your Terra Preta

 How to build the simplest Terra Preta Stove


About size

The italian company Worldstove has created an oven for your pocket: The Beaner.

With this you could make a cop of coffe on the road with some pinecones or an old newspaper. But the tiny stove is rather sensible to the conditions of the burning material. When the diameter rises above 15 cm and approximately double hight burning is unparalleled easier.

Choice of material

Any scrapheap will give you some tin cans with different sizes. Remember, that cans, which contained chemicals, might become lethal when exposed to high temperatures! So stick to the ones uses for food. While the cans easily are transformed into stoves with the use of a simple knife, they are well suited for a start, although they do not stand the fire over the years.

Building instructions

Given you find to adequate tin cans your tools will be a stiff knife.

The inner tin can: Cut out buttom and top.

The outer tin can: Cut out the buttom. Cut the hole in the top as seen to the right under.

– 8 The Terra Preta Stove. The simplest Woodgasstove, providing charcoal for your Terra Preta


Inner tin can to the left and outer tin can to the right.

At the picture underneath you will se the few crucial dimensions.

The space for air intake (1) is created by placing your stove on some stones or rods.

If the space between the two tin cans (2) is too narrow, there will not be enough hot air to burn all the woodgasses. You might see flames and gas over the stove.

It the space (2) is too big, the air will arrive at the top of the stove without the right temperature to ignite the gasses. You might have small flames within the burning chamber; the gasses will not burn, and over the stove you will have nothing but smoke. The space (3) is less sensitive, but should be at least as big as (2).


The one tin can situated within the other with the crucial three spaces indicated.

– Dedicated to the Healing of Mother Earth


* Recepten en de samenstelling van Terra Preta

Een composttoilet of droogtoilet met een gescheiden inzameling voor de droge en natte stoffen is een handig begin.

… Door nu een mengsel van fecaliën, akkerafval, en houtskool te mengen en deze in potten te laten rotten, ontstond er een zeer vruchtbaar mengsel. Deze werd of door de aarde verwerkt, of gewoon over de aarde uitgestort.

Momenteel is er veel onderzoek hier in Duitsland gaande over deze “black earth”.
Er zijn grote verbeteringen aangetoond in vruchtbaarheid en vochtopslag van de akkergronden. Men heeft uiteraard wel de samenstelling aangepast aan de Europese omstandigheden.

Prof. Bruno Glaser, Terra-preta expert zegt hier over:„Bei der Mischung von Kohle und Kompost im Freiland kommt es auf das Mischungsverhältnis an. Wir mischen hier zwei Teile Kompost und einen Teil Biokohle. Und das Ausgangsmaterial für den Kompost muss natürlich auch nährstoffreich sein. Pferdemist oder stickstoffreiche Abfälle sind besser als holzige oder Strohabfälle.“

De biokoolstof, men neme hiervoor bijvoorbeeld fijngemaakte houtkool voor, moet eerst door de compost chemisch geactiveerd worden.

“Sie muss durch Kompost chemisch aktiviert werden. Dann kann sie aufgrund ihrer porösen Struktur das Wasser wie ein Schwamm speichern. Außerdem sorgen Milliarden von Kompostmikroben dafür, dass die Kohle im Boden viele Nährstoffe halten kann und der Humusanteil stabil bleibt. Dauerhumus entsteht. Fruchtbare ´Terra preta”. Aldus Prof. Bruno Glaser.

Das brasilianische Tropenforschungsinstitut Museu Goeldi in Belém startete vor drei Jahren einen ersten Langzeitversuch, Terra Preta neu zu bilden. 25 Jahre lang sollen auf einer vier Hektar großen Fläche bei Tailandia im Bundesstaat Para immer wieder verkohltes Sägemehl in den Boden eingearbeitet werden. Als organischen Dünger verwenden die Forscher zerkleinerte Schlachtabfälle und Rinderblut. Wie schnell sich auf diese Weise eine typische Terra Preta bildet, ist noch ungewiss.

This was from Janice Thies posted on the original thread:
Lastly, from my personal gardening experiences, I use spent charcoal from the filters of the 14 aquaria I maintain for my viewing pleasure. I combine it as about 5% of my mix with 65% peat moss, 10% vermicompost (from my worm bin in my basement where I compost all my household kitchen waste – aged and stabilized, not fresh!), 5-10% leaf mulch (composted on my leafy property in NY), 5-7% perlite to increase drainage, decrease bulk density and improve water retention and percolation, and some bone meal and blood meal (to taste 🙂 ). This makes an excellent potting mix for my indoor ‘forest’. I am very much still playing around with this.

I make an aquarium soil that is similar to what you do at least from the charcoal point of view.

– Azzola Compost
– Ground charcoal
– Earth Worm Castings
– Peat Compost
– Oak Tree Leaves (ground)
– Oak Tree Leaves (whole)
– Lava Rock Flour
– Phosphate Rock Flour

* Ramona’s recipe for home-made dirt (Terra Preta Soil):

  1. A partner with a lot of stamina (helps but is not absolutely necessary)

  2. Two sledge hammers

  3. A sharp, short hoe

  4. An earth-tamping tool

  5. A large umbrella with stand, for shade to work in

  6. Safety glasses

  7. Sun hats

  8. Some very understanding, forgiving, or just hard-of-hearing neighbours

  9. Several bags of charcoal – as many as you have the stamina or attention span for; it helps a lot to open the bags and leave them out under the sprinklers for a few days or weeks to get it good and wet, to make it easier to break up. I do not recommend mesquite, and it is devilishly hard and difficult to break. Use Cowboy brand or some other brand that does not have chemicals added.

  10. A large shallow bin for breaking the charcoal into

  11. Some concrete pavers to put under the shallow bin, to provide a firm surface for breaking the charcoal

  12. Some buckets, or plant pots to pour the broken charcoal into (or you can just dump it from the shallow bin directly onto the ground, for that matter)

  13. Some nitrogen (there is no science to tell you how much to use – just follow your instincts; my advice is to apply somewhat less nitrogen than charcoal)

  14. Some soil life (beneficial fungi, bacteria, nematodes, and earthworms)

  15. Compost

  16. Perlite (gesteente)

  17. Water

  18. Some organic fertilizer, if you want to jump-start things

  19. One citrus-flavored soft drink (for the terra preta and maybe one for you too)

  20. One cheap stale beer (for the terra preta)

  21. Some good cold fresh beer (for you)

  22. A strong back, or else a chiropractor who’s on call

  23. A whole lot of glucosamine and analgesics for your back, whether or not you have a chiropractor

  24. A lot of shampoo, soap, a good scrubber, and hot, hot water because you’re going to **seriously** need a shower when this is all done

Now you have probably discerned from this list, that making terra preta soil is not for the feeble of body or faint of heart. I will get into the details of what to do with all of the above later; but I want to digress a bit first.

First of all, my own high-stamina partner-ingredient for this recipe is Michael P. Byron, author of “Infinity’s Rainbow: The Politics of Energy, Climate and Globalization” and “The Path Through Infinity’s Rainbow: Your Guide to Personal Survival and Spiritual Transformation in a World Gone Mad.” You can find links for these wonderful books on Mike’s webpage at:

* Meer info?