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  • From: "Lawrence F. London, Jr." <lfl@intrex.net>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: [permaculture] [Fwd: [SANET-MG] Putting the carbon back: Black is the new green] + Terra Preta
  • Date: Wed, 09 Aug 2006 21:13:44 -0400

-------- Original Message --------
Subject: [SANET-MG] Putting the carbon back: Black is the new green
Date: Wed, 9 Aug 2006 20:06:37 -0400
From: Joel Gruver <jgruv@HOTMAIL.COM>
Reply-To: Sustainable Agriculture Network Discussion Group
<SANET-MG@LISTS.IFAS.UFL.EDU>
To: SANET-MG@LISTS.IFAS.UFL.EDU

Hello folks,

I was a bit surprised to find a News Feature in the current issue of Nature
about a session that I attended at the WCSS :->

Summaries of the WCSS posters and oral presentations related to Terra Preta
can be accessed via the following links:

http://crops.confex.com/crops/wc2006/techprogram/S2029.HTM
http://crops.confex.com/crops/wc2006/techprogram/S2028.HTM

Joel

***************************************
http://www.nature.com/nature/journal/v442/n7103/full/442624a.html

News Feature
Nature 442, 624-626(10 August 2006) | doi:10.1038/442624a; Published online
9 August 2006
Putting the carbon back: Black is the new green
Emma Marris - Washington correspondent for Nature.

In 1879, the explorer Herbert Smith regaled the readers of Scribner's
Monthly with tales of the Amazon, covering everything from the tastiness of
tapirs to the extraordinary fecundity of the sugar plantations. "The
cane-field itself," he wrote of one rum-making operation, "is a splendid
sight; the stalks ten feet high in many places, and as big as one's wrist."
The secret, he went on, was "the rich terra preta, 'black land', the best on
the Amazons. It is a fine, dark loam, a foot, and often two feet thick."

Last month, the heirs to Smith's enthusiasm met in a hotel room in
Philadelphia, Pennsylvania, during the World Congress of Soil Science. Their
agenda was to take terra preta from the annals of history and the backwaters
of the Amazon into the twenty-first century world of carbon sequestration
and biofuels.

They want to follow what the green revolution did for the developing world's
plants with a black revolution for the world's soils. They are aware that
this is a tough sell, not least because hardly anyone outside the room has
heard of their product. But that does not dissuade them: more than one eye
in the room had a distinctly evangelical gleam.

The soil scientists, archaeologists, geographers, agronomists, and
anthropologists who study terra preta now agree that the Amazon's dark
earths, terra preta do índio, were made by the river basin's original human
residents, who were much more numerous than formerly supposed. The darkest
patches correspond to the middens of settlements and are cluttered with
crescents of broken pottery. The larger patches were once agricultural areas
that the farmers enriched with charred trash of all sorts. Some soils are
thought to be 7,000 years old. Compared with the surrounding soil, terra
preta can contain three times as much phosphorus and nitrogen. And as its
colour indicates, it contains far more carbon. In samples taken in Brazil by
William Woods, an expert in abandoned settlements at the University of
Kansas in Lawrence, the terra preta was up to 9% carbon, compared with 0.5%
for plain soil from places nearby1.

From Smith's time onwards, the sparse scholarly discussion of terra preta
was focused mainly on the question of whether 'savages' could have been so
clever as to enhance their land's fertility. But Woods' comprehensive
bibliography on the subject now doubles in size every decade. About 40% of
the papers it contains were published in the past six years.

Loam ranger
The main stimulus for this interest was the work of Wim Sombroek, who died
in 2003 and is still mourned in the field. Sombroek was born in the
Netherlands in 1934 and lived through the Dutch famine of 1944 - the
Hongerwinter. His family kept body and soul together with the help of a
small plot of land made rich and dark by generations of laborious
fertilization. Sombroek's father improved the land in part by strewing it
with the ash and cinders from their home. When, in the 50s, Sombroek came
across terra preta in the Amazon, it reminded him of that life-giving
'plaggen' soil, and he more or less fell in love. His 1966 book Amazon Soils
began the scientific study of terra preta.

Since then trial after trial with crop after crop has shown how remarkably
fertile the terra preta is. Bruno Glaser, of the University of Bayreuth,
Germany, a sometime collaborator of Sombroek's, estimates that productivity
of crops in terra preta is twice that of crops grown in nearby soils2. But
it is easier to measure the effect than explain it through detailed
analysis.

Everyone agrees that the explanation lies in large part with the char (or
biochar) that gives the soil its darkness. This char is made when organic
matter smoulders in an oxygen-poor environment, rather than burns. The
particles of char produced this way are somehow able to gather up nutrients
and water that might otherwise be washed down below the reach of roots. They
become homes for populations of microorganisms that turn the soil into that
spongy, fragrant, dark material that gardeners everywhere love to plunge
their hands into. The char is not the only good stuff in terra preta -
additions such as excrement and bone probably play a role too - but it is
the most important factor.

Leaving aside the subtleties of how char particles improve fertility, the
sheer amount of carbon they can stash away is phenomenal. In 1992, Sombroek
published his first work on the potential of terra preta as a tool for
carbon sequestration3. According to Glaser's research, a hectare of
metre-deep terra preta can contain 250 tonnes of carbon, as opposed to 100
tonnes in unimproved soils from similar parent material. The extra carbon is
not just in the char - it's also in the organic carbon and enhanced
bacterial biomass that the char sustains.

Ground control
That difference of 150 tonnes is greater than the amount of carbon in a
hectare's worth of plants. That means turning unimproved soil into terra
preta can store away more carbon than growing a tropical forest from scratch
on the same piece of land, before you even start to make use of its enhanced
fertility. Johannes Lehmann of Cornell University in Ithaca, New York, has
studied with Glaser and worked with Sombroek. He estimates that by the end
of this century terra preta schemes, in combination with biofuel programmes,
could store up to 9.5 billion tonnes of carbon a year - more than is emitted
by all today's fossil-fuel use4.

Mud pack
The year before he died, Sombroek helped to round up like-minded colleagues
into the Terra Preta Nova group, which looks at the usefulness of using char
in large-scale farming and as a carbon sink. The group was well represented
at the Philadelphia meeting, although Glaser was not there. Their aim is to
move beyond the small projects in which many of them are involved and find
ways of integrating char into agribusiness. After all, wherever there is
biomass that farmers want to get rid of and that no one can eat, char is a
possibility. That means there are a lot of possibilities.

One problem is that there is a new competitor for farm waste. Plant are
largely made up of cellulose, indigestible material in cell walls. Recent
technological advances make it likely that quite a lot of that cellulose
might be turned into biofuel. At the moment, ethanol is made from corn in
the United States and from sugar in Brazil; if it were made directly from
cellulose, producers could work with a wider range of cheaper biomass. Given
the choice of turning waste material into fuel or into charcoal, farmers
might be expected to go for fuel, especially if that is the way that
policy-makers are pushing them: US President George W. Bush promised $150
million for work on cellulosic ethanol in his 2006 state of the union
speech.

But Lehmann and his colleagues don't see biofuel as an alternative to char -
they see the two developing hand in hand. Take the work of Danny Day, the
founder of Eprida. This "for-profit social-purpose enterprise" in Athens,
Georgia, builds contraptions that farmers can use to turn farm waste into
biofuel while making char. Farm waste (or a crop designed for biofuel use)
is smouldered - pyrolysed, in the jargon - and this process gives off
volatile organic molecules, which can be used as a basis for biodiesel or
turned into hydrogen with the help of steam. After the pyrolysation, half of
the starting material will be used up and half will be char. That can then
be put back on the fields, where it will sequester carbon and help grow the
next crop.

The remarkable thing about this process is that, even after the fuel has
been burned, more carbon dioxide is removed from the atmosphere than is put
back. Traditional biofuels claim to be 'carbon neutral', because the carbon
dioxide assimilated by the growing biomass makes up for the carbon dioxide
given off by the burning of the fuel. But as Lehmann points out, systems
such as Day's go one step further: "They are the only way to make a fuel
that is actually carbon negative".

Slow burn: the idea of using charcoal to sequester carbon may take a while
to catch on.
Day's pilot plant processes 10 to 25 kg of Georgia peanut hulls and pine
pellets every hour. From 100 kg of biomass, the group gets 46 kg of carbon -
half as char - and around 5 kg of hydrogen, enough to go 500 kilometres in a
hydrogen-fuel-cell car (not that there are many around yet). Originally, Day
was mostly interested in making biofuel; the char was just something he
threw out, or used to make carbon filters. Then he discovered that his
employees were reaping the culinary benefits of the enormous turnips that
had sprung up on the piles of char lying around at the plant. Combining this
char with ammonium bicarbonate, made using steam-recovered hydrogen, creates
a soil additive that is now one of his process's selling points; the
ammonium bicarbonate is a nitrogen-based fertilizer.

"We don't maximize for hydrogen; we don't maximize for biodiesel; we don't
maximize for char," says Day. "By being a little bit inefficient with each,
we approximate nature and get a completely efficient cycle." Robert Brown,
an engineer at Iowa State University in Ames, has a $1.8-million grant from
the United States Department of Agriculture (USDA) to fine-tune similar
technology, although being in Iowa, he uses corn stalks not peanut hulls.
"We are trying an integrated approach: we are trying to evaluate the
agronomic value, the sequestration value, the economic value, the
engineering," he says.
Brown thinks a 250-hectare farm on a char-and-ammonium-nitrate system can
sequester 1,900 tonnes of carbon a year. A crude calculation on that basis
suggests the US corn crop could sequester 250 million tonnes of carbon a
year. At the moment, no one knows how long this could go on; no one has yet
found a ceiling for char addition.

Stephen Joseph of Biomass Energy Services and Technology in New South Wales
has built a number of char-producing machines in Australia that work at
fairly large scales (the models have grown from an original 'Piglet' through
a larger 'Daisy' to a positively bullish 'El Toro'). Joseph looks for
companies with a waste problem such as a paper mill with spare scraps or a
dairy with old bedding and manure, and then integrates char production into
the business so that the heat produced in pyrolysis is used where the firm
needs it.
So far, Joseph's company is being brought in to solve waste-management
problems, but he hopes the value of the char will become a selling point in
itself. For that to happen, however, he needs some help. His machines can be
tuned to make char of various sorts: different sized particles with
different sized pores and different amounts of other elements. Which is the
best? It's a question he asks in Philadephia, and one of the things that
Brown's research in Iowa aims to find out.

The right protocol
Such technical unknowns are not the only obstacles on the road to a black
revolution. One problem is that the purported benefits of char do not slot
easily into the framework of the Kyoto Protocol, an international agreement
to reduce carbon emissions. Lehmann hopes to see the process get going under
the aegis of the protocol's Clean Development Mechanism, in which rich
countries sponsor green projects in poor countries and get credit for the
reduced emissions. To this end, he is amassing evidence that modern char
techniques can actually keep the carbon involved locked up for centuries.
His Cornell colleague John Gaunt is working on ways to present the technique
as the sort of 'change in practice' that could count as a tradeable
carbon-emission reduction of the sort allowed under Kyoto.

Then there are your risk-averse farmers. They haven't heard of char. And
they aren't going to buy it - let alone buy a strangely named machine to
make it - unless they know it will make them money. It is no good pitching
it to them with a mouthful of scientific caveats about not knowing the right
kind of char for each type of soil or exactly how it works. You have to be
able to sell specific benefits and real attractions. "A lot of farmers are
environmentalists," says John Kimble, a USDA man who has just retired from
the National Soil Survey Center in Lincoln, Nebraska. "But they look at the
bottom line, as we all do."

After the afternoon coffee break in Philadelphia, Kimble takes the podium
and the wind out of everyone's sails. He is sympathetic to the terra pretans
goals - indeed he was a good friend of Sombroek's - but that doesn't stop
him asking hard questions. "Can you do this in a no-till way?" is one tricky
query. Kimble and many others have been pushing no-till farming, which
basically means doing without ploughs, as a partial solution to erosion,
pesticide run-off and fuel costs. The idea is that the less you mess with
the soil, the less its components separate and wander away. But biochar is
light and fine, like the black grit left in a barbecue. If you don't
physically insert it into the soil, it might just blow away.

Everyone listens politely. But while watching their responses, it was hard
not to worry that the same enthusiasm that has brought them together might
also trap them in a cul de sac. They obviously respect economics and
pragmatic requirements. But these are not people principally moved by
practical politics or bottom lines; they are people moved by ideals. They
start from the basis that the answer lies in the soil, more or less whatever
the question is, and can't quite understand why this isn't self-evident to
everyone else. Faced, for example, with the suggestion that all corn matter
be turned into ethanol, they tend simply to say "Well it could be - but we
hope, of course, it will go into the soil." They know they ought to be
marketing terra preta as a resource, or a policy instrument; but they can't
stop seeing it as a wonder.

Policy is not always, or even often, dictated by pure rationality. Perhaps
terra preta's compelling history and rich, earthy smell will go to the heads
of that diffuse band of policy-makers who hand out the cash. The enthusiasts
need to be more down to earth; but the policy people might benefit from
getting their hands dirty.

References
Woods, W. I. & McCann, J. M. in Yearbook Conf. Latin Am. Geogr. Vol. 25 (ed.
Caviedes, C.) 7-14. (Univ. Texas, Austin, 1999).
Glaser, B. Phil. Trans. R. Soc. (in the press).
Sombroek, W. G. Interciência 17, 269-272 (1992).
Lehmann, J. , Gaunt, J. & Rondon, M. Mitigation Adapt.Strateg. Global Change
11, 403-427 doi:10.1007/s11027-005-9006-5 (2006).






  • [permaculture] [Fwd: [SANET-MG] Putting the carbon back: Black is the new green] + Terra Preta, Lawrence F. London, Jr., 08/09/2006

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