November 22, 2006

Terra Preta: Black is the New Green

In August I cited an article on Terra Preta that focused on an organic method of sequestering carbon in the soil.

On the World Changing website, I recently ran across an article and a conversion technology animation involving pyrolysis and the generation of charcoal for the production of a high carbon fertilizer. Such a process would not only add to the sustainability of soil for the cultivation of healthy crops, but also provide a carbon sink alternative to geosequestration methods.

Terra Preta: Black is the New Green
by David Zaks and Chad Monfreda

Carbon sequestration faces some major hurdles. Technical geosequestration methods could pump large amounts of CO2 deep underground but are still under development. On the other hand, natural methods that store carbon in living ecosystems may be possible in the short term but require huge swathes of land and are only as stable the ecosystems themselves. An ideal solution, however, would combine the quick fix of biological methods with the absolute potential of technical ones. Terra preta may do just that, as a recent article in the journal Nature reveals.

The difference between terra preta and ordinary soils is immense. 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. To understand what this means, the difference in the carbon between these soils matches all of the vegetation on top of them. Furthermore, there is no clear limit to just how much biochar can be added to the soil.

Claims for biochar's capacity to capture carbon sound almost audacious. Johannes Lehmann, soil scientist and author of Amazonian Dark Earths: Origin, Properties, Management, 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!

Biofuels are touted as 'carbon neutral', but biofuels and biochar together promise to be 'carbon negative'. Danny Day, the founder of a company called Eprida is already putting these concepts into motion with systems that turn farm waste into hydrogen, biofuel, and biochar.

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-Tropsch gas-to-liquids diesel (BTL diesel), as well as the ammonia used to enrich the carbon to make ECOSS fertilizer.

Terra preta's full beauty appears in this closed loop. Unlike traditional sequestration rates that follow diminishing marginal returns-aquifers fill up, forests mature-practices based on terra preta see increasing returns. Terra preta doubles or even triples crop yields. More growth means more terra preta, begetting a virtuous cycle. While a global rollout of terra preta is still a ways away, it heralds yet another transformation of waste into resources.

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ru said...

Fantastic. Do you know anything about the longevity of the carbon retained in terra preta. What are the flow back rates of the C to the atmosphere as CO2?
At we plant trees for airline passengers concerned about their emissions and we are looking at different ways to reduce the inevitable return of the C to the air, once the tree has grown to maturity.
Any help appreciated.

Erich J. Knight said...

Hi Ru,

Terra Preta will hold C for 1000 to 2000 years, the papers showing the carbon dating and many other links on Amazon Dark Soils (ADS)are posted here:

This science forum has had 10,000 viewers and 214 replies. It is a most valuable resource for anyone to get up to speed on Terra Preta. I post everything that I find on the subject there.
I have been researching the topic for several months now and just want to pass along to you , for desemination, what I feel is this most comprehensive ADS science forum site.

I have promoted ADS to a broad range of Science writers and luminaries in the many fields to which it is relevant. Every time I see an article on energy, Bio-fuels, agriculture, Climate or find a company with complementary technology, off goes my standard TP posting.

Have you contacted the Chicago Carbon Exchange about your service?

The upcoming International Agrichar Initiative (IAI) conference is to be held at Terrigal, NSW, Australia in 2007. ( )


Erich J. Knight said...

spoke with the author of a Terra Preta (TP) story in Solar Today, Ron Larson ,
he said he spoke with a major National Geographic editor, who is preparing a big article on TP. but Doesn't know when it will be out.

In E. O. Wilson's "The Future of Life" he opens the book with a letter to Thoreau updating him on our current understanding of the nature of the ecology of the soils at Walden Pond.

" These arthropods are the giants of the microcosm (if you will allow me to continue what has turned into a short lecture). Creatures their size are present in dozens-hundreds, if an ant or termite colony is presents. But these are comparatively trivial numbers. If you focus down by a power of ten in size, enough to pick out animals barely visible to the naked eye, the numbers jump to thousands. Nematode and enchytraied pot worms, mites, springtails, pauropods, diplurans, symphylans, and tardigrades seethe in the underground. Scattered out on a white ground cloth, each crawling speck becomes a full-blown animal. Together they are far more striking and divers in appearance than snakes, mice, sparrows, and all the other vertebrates hereabouts combined. Their home is a labyrinth of miniature caves and walls of rotting vegetable debris cross-strung with ten yards of fungal threads. And they are just the surface of the fauna and flora at our feet. Keep going, keep magnifying until the eye penetrates microscopic water films on grains of sand, and there you will find ten billion bacteria in a thimbleful of soil and frass. You will have reached the energy base of the decomposer world as we understand it 150 years after you sojourn in Walden Woods."

Certainly there remains much work to just characterize all the estimated 1000 species of microbes found in a pinch of soil, and Wilson concludes at the end of the prolog that
"Now it is up to us to summon a more encompassing wisdom."

I wonder what the soil biome was REALLY like before the cutting and charcoaling of the virgin east coast forest, my guess is that now we see a severely diminished community, and that only very recent Ag practices like no-till have helped to rebuild it.

I found this study in this TP forum :

First-ever estimate of total bacteria on earth

Erich J. Knight said...

RE: Nature Article — the link given will not allow access without being a subscriber to Nature.

I posted it Before Nature started requiring a subscribing membership, here is a link to the original pdf version. The pdf version is still accessible without a membership.