‘Black gold’ may revolutionise farming, curb global warming (mo' terra preta)

[jpak]

http://www.thaindian.com/newsportal/world-news/black-gold-may-revolutionise-farming-curb-global-warming_10036729.html

Washington, April 11 (IANS) Scientists have discovered an extraordinary source of some of the richest, most fertile soil in the world, often called ‘black gold’. They simply have to mix charcoal in the soil. And it can battle global warming as well by holding the carbon in the soil instead of letting it escape into the atmosphere, according to a new study.

The discovery goes back 1,500 years to the central Amazon basin where tribal people mixed their soil with charcoal derived from animal bone and tree bark.

This indigenous and “revolutionary” farming technique holds promise as a cheap, carbon-negative strategy to rein in world hunger and curb the emission of greenhouse gases by trapping them in the charcoal-laced soil.

“Charcoal fertilisation can permanently increase soil organic matter content and improve soil quality, persisting in soil for hundreds to thousands of years,” said Mingxin Guo of Delaware State University and co-author of the study.

<more>

[mike_c]

1. this is embarassing....

I don't know where to begin....

First, the source of charcoal is, um, trees-- trees that do a far better job of sequestering carbon than charcoal does. Charcoal enriches soil because anoxic burning partially breaks down insoluble cellulose and grinding it to a powder increases its surface area, hastening microbial decomposition to release mineral nutrients that were not converted to smoke during the charcoal manufacturing process. The charcoal particles also help hold some soluble mineral nutrients in the soil that would normally undergo cation replacement leaching, IIRC. But the main point is that release of those bound nutrients requires decomposition of the charcoal itself, returning its carbon to the atmosphere as CO₂. Getting at those nutrients HASTENS the oxidation of carbon to CO₂.

Burning forests is not a good carbon sequestration strategy.

[GliderGuider]

2. The reason charcoal is better than trees for carbon sequestration

Charcoal moves the carbon from the original trees underground in a very stable form that will stay there potentially for thousands of years. This frees up the land area where the original woody material grew, so it can grow more trees and capture more carbon. A mature tree does not take up much new carbon each year - that happens mainly during the growth phase. If the plant is harvested and charred at the end of its high-growth period, a new plant can keep the growth and carbon capture going on the same piece of land, as opposed to having the original plant slide into a long period of relative carbon inactivity. This is why probable candidates for terra preta operations are coppice poplar or willow, or bamboo. Frequent harvesting is the key.

Charcoal underground is essentially pure carbon, and doesn't directly add much to the soil in the way of nutrients. Pure carbon underground is not significantly broken down by either organic action or oxidation, which is why it lasts in the soil for many centuries. The fertility enhancing properties of charcoal seem to come from its porous structure, which provides an ideal substrate for bacterial and fungal colonies. Their activity is what improves the soil fertility by doing things like fixing nitrogen and providing various organic incorporations of soil minerals.

[mike_c]

7. not sure I agree....

This probably needs a more considered response but I have to run to class in a few minutes. First, the statement that mature trees don't take up carbon-- if the leaves are expanded and the stomates open, and the sun is shining, mature trees are photosynthesizing, and thus fixing carbon. The rate of production often slows on a per mass basis after canopy establishment, so yes, frequent harvest is useful but only if that rapidly sequestered carbon isn't simply oxidized back into the atmosphere.

I'm presuming that small charcoal particles will be easy fodder for microbial digestion back to CO₂ as long as the soil is not hypoxic, which is usually the case in the root zones of crops. Converting them to ground charcoal should be the physical equivalent of processing them through the guts of microarthropods, which dramatically increases the decomposition rate. You're saying that conversion to charcoal SLOWS that process? That the main fertilizer benefit comes from retention of soluble nutrients with rapid ionic exchange rates, rather than release of intrinsic nutrients (which is decomposition, and oxidizes carbon back to CO₂)? Hmmm.... I'll wait to see the data I suppose.

on edit: and where does the energy for anoxic burning of all that biomass come from? Old style charcoal burners release tremendous amounts of CO₂ to subsidize the conversion of a portion of the biomass to charcoal.

[bananas]

9. It will be discussed on Science Friday today (NPR)

www.sciencefriday.com
somebody just posted it in gd: http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=389x3143705
Ira Plato on Science Friday NPR
Will finally discuss "Terra Preta". Using charcoal in soil.
replies:
1. Flatow.
Ira Flatow.

[izquierdista]

13. He's right

Carbon in its elemental form is not usable by microbes. That's why coal tailing dumps are devoid of plant growth (that and all the toxic metals along with the detritus). Also, where is all the gunk in your aquarium? On the glass wool and other padding, but never on the activated charcoal.

[mike_c]

14. that's true....

But damn, significant swaths of Europe were permanantly deforested to make charcoal. It's hard for me to accept that the energy and carbon balance for that sort of thing could be made to work out well. Slash and char as a substitute for slash and burn, sure, especially on lateritic tropical oxisols, but I thought the OP advocated broad scale conversion of temperate forest to charcoal. I was thinking it would hasten decomposition, though. Maybe not.

[GliderGuider]

15. The charcoal made in Europe was subsequently burnt, not buried.

Nobody's advocating taking existing forest and turning it into charcoal. That would have much broader implications beyond just carbon sequestration. I guess this process could compete with switchgrass for all the marginal ex-agricultural land that's apparently out there...

The one problem nobody's looked at yet that I'm aware of, is the water requirement. A rapid-growth plantation of bamboo or coppice poplar would require quite a bit of fresh water -- one commodity that's in pretty short supply in many places already. We might want to preserve what's left for food production.

I suspect we may already be in the ecological/civilizational equivalent of coffin corner*. If we try to speed up we will lose control, and if we slow down we stall and lose control. It seems like any adjustment we try to make to our predicament at this point (like using terra preta for CCS) introduces a new destabilizing force (loss of critical fresh water supplies).

The coffin corner or Q-Corner is the altitude at or near which an aircraft's stall speed is equal to the critical Mach number, at a given gross weight and G loading. At this altitude the aircraft becomes nearly impossible to keep in stable flight. Since the stall speed is the minimum speed required to maintain level flight, any reduction in speed will cause the airplane to stall and lose altitude. Since the critical Mach number is maximum speed at which air can travel over the wings without losing lift to flow separation and shock waves, any increase in speed will cause the airplane to lose lift, or to pitch heavily nose-down, and lose altitude. The "corner" refers to the triangular shape at the top of a flight envelope chart where the stall speed and critical Mach number lines come together.

[jpak]

18. *ahem* Carbon-Negative Biofuels from Low-Input High-Diversity Grassland Biomass

:evilgrin:

http://www.sciencemag.org/cgi/content/abstract/314/5805...

Carbon-Negative Biofuels from Low-Input High-Diversity Grassland Biomass

David Tilman,1* Jason Hill,1,2 Clarence Lehman1

Science 8 December 2006: Vol. 314. no. 5805, pp. 1598 - 1600

ABSTRACT

Biofuels derived from low-input high-diversity (LIHD) mixtures of native grassland perennials can provide more usable energy, greater greenhouse gas reductions, and less agrichemical pollution per hectare than can corn grain ethanol or soybean biodiesel. High-diversity grasslands had increasingly higher bioenergy yields that were 238% greater than monoculture yields after a decade. LIHD biofuels are carbon negative because net ecosystem carbon dioxide sequestration (4.4 megagram hectare–1 year–1 of carbon dioxide in soil and roots) exceeds fossil carbon dioxide release during biofuel production (0.32 megagram hectare–1 year–1). Moreover, LIHD biofuels can be produced on agriculturally degraded lands and thus need to neither displace food production nor cause loss of biodiversity via habitat destruction.

1 Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN 55108, USA.
2 Department of Applied Economics, University of Minnesota, St. Paul, MN 55108, USA.

<end>

Furthermore....

Biochar feed-stocks can use any plant material - prairie grasses, urban leaf and tree debris, corncobs, corn stover, wheat straw, wheat and sunflower hulls etc.

A small fraction of "ag waste" (sic) could be used to produce biochar (with heat and electricity - or- liquid biofuel produced from pyrolysis gases) and returned to fields. The majority of the "ag waste" (sic) could be immediately to the soil as well. Over a period of years, biochar soil concentrations would increase to maintain and sustain soil fertility.

No industrial monoculture forestry required...

[GliderGuider]

19. We already covered this paper in the "Green gasoline" thread.

I will retain my skepticism until operational evidence has been presented. Until then it's just pie in the sky with scientific notation.

[jpak]

25. My apologies - I forget, anything that isn't Big D Doom isn't possible...

:evilgrin:

[GliderGuider]

26. I never said it wasn't possible, I said we had no operational data yet.

There's a significant difference.

I'm quite supportive of terra preta. I am skeptical about plans to use biomass to fuel industrial civilization, but that just means the data needs to be solid before I'll support such a proposal. We may find a way to do it that doesn't increase ecological degradation, and some way to ensure that it doesn't expand to the point where it does. If we can do that, let's go for it. But show me some operational data first.

[Fovea]

23. A single manor/shire went through 10 acres of wood

per month, IIRC.

[kristopher]

16. self delete

[kestrel91316]

20. Good news for the trees, mike_c. They can actually make biochar

out of just about ANY waste organic matter, including sewage sludge and such. I envision a new use for those lagoons full of cow and pig manure.

The biochar persists in the soil for hundreds or thousands of years, and the soil enrichment is not a function of its breakdown.

[shraby]

3. Does this mean that tossing the contents

of the charcoal grill into the garden after using it is a good thing?

[GliderGuider]

4. No, it means tossing the contents into the garden "before" using it is a good thing.

Afterwards it's not charcoal, ir's just ash, which doesn't do the same thing -- though it's better than nothing.

[shraby]

5. There are always chunks that didn't burn all the

way is why I asked. My parents always tossed the ashes from the wood stove out in the garden too.

[GliderGuider]

6. Yep. Toss it all in. Add some compost for bugs and organics and you're set.

[Zachstar]

17. I used ash on some elephant ear plants.

Never had to water them and before fall they were almost as big as the house.

[jpak]

8. Soil Biogeochemistry of Terra Preta do Indio...

http://www.css.cornell.edu/faculty/lehmann/terra_preta/TerraPretahome.htm

<snip>

Amazonian Dark Earths - implications for soil fertility and land use

In addition to their high soil organic matter contents as mentioned above, Amazonian Dark Earths are characterized by high P contents reaching 200-400 mg P/kg, and higher cation exchange capacity, pH and base saturation than surrounding soils (Sombroek, 1966; Smith, 1980; Kern and Kämpf, 1989; Sombroek et al., 1993; Glaser et al., 2000; Lehmann et al., 2003; Liang et al., 2006). These soils are therefore highly fertile (Lehmann et al., 2003). Fallows on the Amazonian Dark Earths can be as short as 6 months, whereas fallow periods on Oxisols are usually 8 to 10 years long (German and Cravo, 1999). Only short fallows are presumed to be necessary for restoring fertility on the dark earths. However, precise information is not available, since farmers frequently fallow the land due to an overwhelming weed infestation and not due to declining soil fertility. Continuous cropping for longer periods of time appears to be possible from a soil fertility point of view. How long a field can be continuously cropped and what can be done to prolong this period is not yet clear. Petersen et al. (2001) reported that Amazonian Dark Earths in Açutuba were under continuous cultivation without fertilization for over 40 years.

Recent efforts stimulated by Terra Preta research included the investigation of biochar (biomass-derived black carbon or charcoal) as a soil amendment to enhance nutrient availability and retention. Charcoal amendments were shown to significantly decrease nutrient leaching and increase crop growth (Lehmann et al., 2003), and the tests of slash-and-char systems were suggested as an alternative to slash-and-burn (Lehmann et al., 2002).

<more>

http://www.sciencedaily.com/releases/2006/03/060301090431.htm

<snip>

"The result is that about 50 percent of the biomass carbon is retained," Lehmann said. "By sequestering huge amounts of carbon, this technique constitutes a much longer and significant sink for atmospheric carbon dioxide than most other sequestration options, making it a powerful tool for long-term mitigation of climate change. In fact we have calculated that up to 12 percent of the carbon emissions produced by human activity could be offset annually if slash-and-burn were replaced by slash-and-char."

In addition, many biofuel production methods, such as generating bioenergy from agricultural, fish and forestry waste, produce bio-char as a byproduct. "The global importance of a bio-char sequestration as a byproduct of the conversion of biomass to bio-fuels is difficult to predict but is potentially very large," he added.

Applying the knowledge of terra preta to contemporary soil management also can reduce environmental pollution by decreasing the amount of fertilizer needed, because the bio-char helps retain nitrogen in the soil as well as higher levels of plant-available phosphorus, calcium, sulfur and organic matter. The black soil also does not get depleted, as do other soils, after repeated use.

"In other words, producing and applying bio-char to soil would not only dramatically improve soil and increase crop production, but also could provide a novel approach to establishing a significant, long-term sink for atmospheric carbon dioxide," said Lehmann. He noted that what is being learned from terra preta also can help farmers prevent agricultural runoff, promote sustained fertility and reduce input costs.

<more>

The 'Terra Preta' phenomenon: a model for sustainable agriculture in the humid tropics

http://www.springerlink.com/content/ch88m96jtrfrj4gk/

Authors

Bruno Glaser, Ludwig Haumaier, Georg Guggenberger, Wolfgang Zech
1Institute of Soil Science and Soil Geography, University of Bayreuth, 95440 Bayreuth, Germany

Abstract

Many soils of the lowland humid tropics are thought to be too infertile to support sustainable agriculture. However, there is strong evidence that permanent or semi-permanent agriculture can itself create sustainably fertile soils known as 'Terra Preta' soils. These soils not only contain higher concentrations of nutrients such as nitrogen, phosphorus, potassium and calcium, but also greater amounts of stable soil organic matter. Frequent findings of charcoal and highly aromatic humic substances suggest that residues of incomplete combustion of organic material (black carbon) are a key factor in the persistence of soil organic matter in these soils. Our investigations showed that 'Terra Preta' soils contained up to 70 times more black carbon than the surrounding soils. Due to its polycyclic aromatic structure, black carbon is chemically and microbially stable and persists in the environment over centuries. Oxidation during this time produces carboxylic groups on the edges of the aromatic backbone, which increases its nutrient-holding capacity. We conclude that black carbon can act as a significant carbon sink and is a key factor for sustainable and fertile soils, especially in the humid tropics.

Putting the carbon back: Black is the new green

(Nature news feature)

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 Marris1

Abstract

One way to keep carbon dioxide out of the atmosphere is to put it back in the ground. In the first of two News Features on carbon sequestration, Quirin Schiermeier asked when the world's coal-fired power plants will start storing away their carbon. In the second, Emma Marris joins the enthusiasts who think that enriching Earth's soils with charcoal can help avert global warming, reduce the need for fertilizers, and greatly increase the size of turnips.

<much more>

[mike_c]

11. the clarification helps....

Slash and burn practices convert significant amounts of biomass directly to CO₂ and ash. Slash and char slows the release of CO₂. Substituting slash and char for slash and burn, especially on lateritic tropical oxisols makes perfect sense. I thought the OP was making the point that deforestation for charcoal production was a GENERALLY good carbon sequestration strategy-- something that makes no sense at all!

[GreenPartyVoter]

10. A lot of people around here burn their blueberry fields every fall for that reason

[mike_c]

12. that's much closer to slash and burn....

Most of the biomass is converted to CO₂ and ash. The ash is rich in mineral nutrients, so it supports rapid growth of new brush, plus regular burning arrests succession that would eventually shade out berry production.

Making terra preta requires charcoal-- wood heated to burning temperatures but in the absence of oxygen-- and deep churning to create storage pools.

[NNadir]

21. Self delete.

[NNadir]

22. Oh good. More reason to burn stuff.

I recently published a diary on the wonderful Norwegian commentary about put wood ashes in forests.

It's called "Norwegian Wood and Heavy Metal" and it's here:

http://www.dailykos.com/story/2008/3/7/21421/65163/25/470856

According to the Norwegian scientists cited therein, wood ash is too toxic to dump in forests when compared to things like sewage sludge.

Of course, it happens that activated charcoal typically captures heavy metals which accounts for the high metal content of coal ash, another of the long list of wastes about which the anti-nuke cult couldn't care less.

Effectively charcoal sequesters heavy metals, but um, some of the metals are essential as trace elements, I'll bet.

But let's rush into this. I heard about it on the internet. It must be super.

And let's be clear, this bit of wishful thinking is just another in a long series of wishful thinking events that will make people allow themselves to excuse their dangerous fossil fuel waste burning.

We'll here lots and lots and lots and lots and lots and lots and lots of could sentences, like "our new high efficiency combined cycle coal plants are OK because we could capture 1,000 brazillion tons of charcoal by 2099" The claimants for this bit of course, will be dead in 2099 and the contempt of historians, should there be historians at all, will not be heard by the causes of such violence, the wishful thinking set of modern times.

Recently this business of charcoal soils has produced a wonderful round of internet wishful thinking. It makes one want to go out and buy a brazillion solar cells to get right with Governor Hydrogen Hummer.

Of course, it seems to immediately escape attention that carbonizing biomass takes energy. This has been true for brazillions of years.

[kristopher]

24. And for brazillions of years

Marvin the depressed nuclear robot with a brain the size of a planet says: "Of course, it seems to immediately escape attention that carbonizing biomass takes energy. This has been true for brazillions of years."

And for brazillions of years, Marvin, humans managed to accomplish the extraction of the energy required from the biomass itself. Amazing huh, they did it without splitting a single atom. But hey, I know that's a bit too simple for your planet sized intellect.

Production of lumber leaves a lot of waste trimmed from the usable trunk at the site where the tree is felled. These leftovers are a big part of the fire hazard that plagues our forests. This means that development of an economic incentive to gather that material instead of leaving it on the forest floor is a two'fer: You get soil enrichment and the energy to produce it.
And just to get the jump on a potential question, the stuff that is now burnt for generating electricity is usually wastage from the trunks that is trimmed off at the sawmill.


I get the impression this can displace petroleum based fertilizers. Is that true?

[jpak]

28. and what do you burn to heat your large upscale suburban house???

natural gas - and lots of it.

burn baby burn

[GliderGuider]

27. An interesting suggestion for TP

All those pine forests that have been devastated by pine beetle infestations would make good feedstock for Terra Preta. It would be a whole lot more useful than just letting the dead pine trees burn (which is what a lot of them are going to do). Tow mobile charcoal retorts into the forest, gather the dead trees using the usual skidding equipment, char them and bury the charcoal in situ to fertilize the next phase of forest regrowth...

Thanks for the reminder, Karen.