BIOCHAR / Terra Preta ("Black Earth")

[zak]

I've done a lot of reading on biochar, and I need to get my millions links organized, but as I do that I was wondering: does anyone have any insights or resources to share? I find the more I research the various topics we're all interested in, the one I always come back to as the most interesting to me is this. I think biochar was mentioned elsewhere in the forum -- maybe it had to do with the James Lovelock article? -- but now I can't find anything.

[Justin Boland]

Source:
http://www.newscientist.com/article/mg2 ... nkind.html

So are we doomed?

There is one way we could save ourselves and that is through the massive burial of charcoal. It would mean farmers turning all their agricultural waste - which contains carbon that the plants have spent the summer sequestering - into non-biodegradable charcoal, and burying it in the soil. Then you can start shifting really hefty quantities of carbon out of the system and pull the CO2 down quite fast.

Would it make enough of a difference?

Yes. The biosphere pumps out 550 gigatonnes of carbon yearly; we put in only 30 gigatonnes. Ninety-nine per cent of the carbon that is fixed by plants is released back into the atmosphere within a year or so by consumers like bacteria, nematodes and worms. What we can do is cheat those consumers by getting farmers to burn their crop waste at very low oxygen levels to turn it into charcoal, which the farmer then ploughs into the field. A little CO2 is released but the bulk of it gets converted to carbon. You get a few per cent of biofuel as a by-product of the combustion process, which the farmer can sell. This scheme would need no subsidy: the farmer would make a profit. This is the one thing we can do that will make a difference, but I bet they won't do it.

Do you think we will survive?

I'm an optimistic pessimist. I think it's wrong to assume we'll survive 2 °C of warming: there are already too many people on Earth. At 4 °C we could not survive with even one-tenth of our current population. The reason is we would not find enough food, unless we synthesised it. Because of this, the cull during this century is going to be huge, up to 90 per cent. The number of people remaining at the end of the century will probably be a billion or less. It has happened before: between the ice ages there were bottlenecks when there were only 2000 people left. It's happening again.

I don't think humans react fast enough or are clever enough to handle what's coming up. Kyoto was 11 years ago. Virtually nothing's been done except endless talk and meetings.

[dlollard]

It so happens, I just read a hard copy of this article on Terra Preta, that someone passed along to us. I looked for it on the publisher's web site, Acres USA, but it didn't come up. Amazingly, a google search brought up a .pdf of the article, right there on Acres USA's site.

For me, the article was a nice introduction to how it worked in the Amazon basin. I've heard all the tidbits but never thoroughly read anything about it. Amazing stuff. Seems like it could do good for re-establishing good soil in landscapes degraded by agriculture and/or sub/urbanization.

Don

[zak]

I'm still trying to corral all the info I've read/gathered on biochar, but in the meantime here is Appropedia's excellent primer:


Biochar

According to the International Biochar Initiative:

Biochar is a fine-grained charcoal high in organic carbon and largely resistant to decomposition. It is produced from pyrolysis of plant and waste feedstocks. As a soil amendment, biochar creates a recalcitrant soil carbon pool that is carbon-negative, serving as a net withdrawal of atmospheric carbon dioxide stored in highly recalcitrant soil carbon stocks. The enhanced nutrient retention capacity of biochar-amended soil not only reduces the total fertilizer requirements but also the climate and environmental impact of croplands. Char-amended soils have shown 50 - 80 percent reductions in nitrous oxide emissions and reduced runoff of phosphorus into surface waters and leaching of nitrogen into groundwater. As a soil amendment, biochar significantly increases the efficiency of and reduces the need for traditional chemical fertilizers, while greatly enhancing crop yields. Renewable oils and gases co-produced in the pyrolysis process can be used as fuel or fuel feedstocks. Biochar thus offers promise for its soil productivity and climate benefits.

Some of the world's most productive soils (e.g. Canadian prairies, Russian Chernozem / or "black earth") are very rich in organic carbon. This is now thought to be pyrogenic in origin, likely originating from prairie or forest fires. The black carbon is often thousands of years old, demonstrating its stability in soil. For more extensive background on Biochar, please look up the Wikipedia entry.


Biochar Economy


(image from Flickr user visionshare by CC license)

Biochar in the Appropriate Technology context

• Inexpensive soil amelioration for degraded land (i.e. biochar as a liming agent)
• Need less land = lower startup costs for a Sustainable Village
• Increased biomass productivity
• Efficient use of biomass waste for energy generation
• Reduced need for fertilizer input (e.g. manure)
• Combine biochar with vermicompost to make superb fertilizer.
• Pyrolysis gas can be used for energy and as a heat source
• Bio-oil and tars are also by-products of pyrolysis, can be turned into biodiesel
• Add charcoal to compost heap to speed up composting (probably works via enhanced microbial activity)
• Biochar for sale as a source of income for an emerging community
• Combine with solar thermal heat source to make a solar pyrolysis unit for charcoal production
• Charcoal is useful for other purposes, e.g. metal smelting
• Charcoal as filter: it has very high absorptive capacities and therfore can be used for water purification and filtration, later become biochar; can also be used to filter pyrolysis gas itself, although it may not be suitable as biochar later (depending on feedstock and potentially hazardous polycyclic aromatic hydrocarbons produced during combustion)
• Lastly, charcoal powder can also neutralize smell when put into a composting toilet. Then it becomes biochar, ultimately.

Suitable Feedstocks

A variety of feedstocks can be used. Since these often constitute agricultural residues in rural communities, a form of waste is turned into an asset. Possible feedstocks include:

• agricultural leftovers: straw, rice hulls, corn stalks, chicken/cattle poop
  
• fast-growing biomass: bamboo, switchgrass, miscanthus,
  
• other: leaf litter, grasses, macroalgae, bones (high P content),

Specifics

The pyrolysis temperature appears to be a critical factor determining char yield vs. energy yield (tradeoff). Flexi-pyrolysis units are being developed that can be set for either char yield or gasification yield. Dry biomass can be pyrolyzed at regular atmospheric pressure. For wet biomass, pyrolysis at higher pressure ("supercritical") may be necessary, requiring a more sophisticated technical set-up.

When large chunks of wood are used as feedstock, the charcoal may need to be crushed before use (beware: coal dust explosion !). Many agrigultural feedstocks and leaf litter will not need to be pulverized but will readily break into smaller pieces by themselves. For information on small-scale gardening, please consult the Gardening with Biochar FAQ, an excellent resource.

Criticism

Critics are worried that large-scale biochar production may increase deforestation. However, a variety of biomass feedstocks other than wood can be used (see above). Old-growth forest is likely not a good feedstock because of extensive pre-processing that would be required.

Links

Wikipedia entry on Biochar
Gardening with Biochar FAQ
BioEnergy Lists: Terra Preta (Biochar)
International Biochar Initiative (IBI)
Biochar Fund
Folke Günther's "the simplest of the simple"

[Justin Boland]

Source:
http://www.motherearthnews.com/Organic- ... -Soil.aspx

To make biochar, pile up woody debris in a shallow pit in a garden bed. Burn the brush until the smoke tins and then damp-down the fire by covering it with about an inch of soil. Let it smolder until the brush is charred, then put the fire out.



Last year, I committed one of the great sins of gardening: I let weeds go to seed. Cleaning up in fall, I faced down a ton of seed-bearing foxtail, burdock and crabgrass. Sure, I could compost it hot to steam the weed seeds to death, but instead I decided to try something different. I dug a ditch, added the weeds and lots of woody prunings, and burned it into biochar, thus practicing a “new” soil-building technique that’s at least 3,000 years old.

What’s biochar? Basically, it’s organic matter that is burned slowly, with a restricted flow of oxygen, and then the fire is stopped when the material reaches the charcoal stage. Unlike tiny tidbits of ash, coarse lumps of charcoal are full of crevices and holes, which help them serve as life rafts to soil microorganisms. The carbon compounds in charcoal form loose chemical bonds with soluble plant nutrients so they are not as readily washed away by rain and irrigation. Biochar alone added to poor soil has little benefit to plants, but when used in combination with compost and organic fertilizers, it can dramatically improve plant growth while helping retain nutrients in the soil.
Amazonian Dark Earths

...

Finding Free Biochar

Biochar’s soil building talents may change the way you clean your woodstove. In addition to gathering ashes (and keeping them in a dry metal can until you’re ready to use them as a phosphorus-rich soil amendment, applied in light dustings), make a habit of gathering the charred remains of logs. Take them to your garden, give them a good smack with the back of a shovel and you have biochar.

If you live close to a campground, you may have access to an unlimited supply of garden-worthy biochar from the remains of partially burned campfires. The small fires burned in chimineas often produce biochar, too, so you may need to look no further than your neighbor’s deck for a steady supply.

Charcoal briquettes used in grilling are probably not a good choice. Those designed to light fast often include paraffin or other hydrocarbon solvents that have no place in an organic garden. Plain charred weeds, wood or cow pies are better materials for using this promising soil-building technique based on ancient gardening wisdom.

How to Make Biochar

To make biochar right in your gardens, start by digging a trench in a bed. (Use a fork to loosen the soil in the bottom of the trench and you’ll get the added benefits of this “double-digging” technique.) Then pile brush into the trench and light it. You want to have a fire that starts out hot, but is quickly slowed down by reducing the oxygen supply. The best way to tell what’s going on in a biochar fire is to watch the smoke. The white smoke, produced early on, is mostly water vapor. As the smoke turns yellow, resins and sugars in the material are being burned. When the smoke thins and turns grayish blue, dampen down the fire by covering it with about an inch of soil to reduce the air supply, and leave it to smolder. Then, after the organic matter has smoldered into charcoal chunks, use water to put out the fire. Another option would be to make charcoal from wood scraps in metal barrels.

I’m part of the Smokey-the-Bear generation, raised on phrases like “learn not to burn,” so it took me a while to warm up to the idea of using semi-open burning as a soil-building technique. Unrestrained open burning releases 95 percent or more of the carbon in the wood, weeds or whatever else that goes up in smoke. However, low-temperature controlled burning to create biochar, called pyrolysis, retains much more carbon (about 50 percent) in the initial burning phase. Carbon release is cut even more when the biochar becomes part of the soil, where it may reduce the production of greenhouse gases including methane and nitrous oxide. This charcoal releases its carbon 10 to 100 times slower than rotting organic matter. As long as it is done correctly, controlled charring of weeds, pruned limbs and other hard-to-compost forms of organic matter, and then using the biochar as a soil or compost amendment, can result in a zero emission carbon cycling system.

[Jecklin]

I use wood ash in soil. As far as biochar, Sharon Astyk mentioned it in a blog post:

Two particular ways of maintaining fertility deserve mention here - fungal soil support, by mycorrhizae (tiny fungus that colonize the soil) and terra preta. Mycorrhizae have a symbiotic relationship with the roots of many plants, and can enhance the ability to plants to uptake nutrients and deal with water stress among other things. Many soils are fungi deficient, and an application of mycorrhizae can improve your plants ability to absorb the nutrients in your soil.

Terra Preta is a fascinating subject - and one still uncertain. Terra Preta involves adding plant based charcoal (ie, not the briquets at the grocery store) to your soil. What this does is still a matter of speculation - it isn’t clear, for example, whether the charcoal itself or the organic processes it enables are actually what creates the rich soil involved. Nor is it clear that all soils respond equally well to terra preta inputs - for example a study found that boreal forest soils did not seem to respond to biochar applications. That said, however, there have been some fascinating results - biochar supplemented soils seem to stimulate nitrogen fixing in legumes, for example, and while charcoal supplemented soils enable plants to take up more minerals, the soils deplete more slowly. I’d encourage everyone to consider experimenting with biochar as a way of improving your soils.

http://sharonastyk.com/2009/02/24/ferti ... fertility/

The entire article on Creating & Sustaining Soil Fertility is good.

[zak]

Woodchips With Everything
Here comes the latest utopian catastrophe: the plan to solve climate change with biochar
by George Monbiot
http://www.commondreams.org/view/2009/03/24-4

Just burying carbon bears little relationship to the complex farming techniques of the Amazon Indians who created terras pretas. Nor is there any guarantee that most of the buried carbon will stay in the soil. In some cases charcoal stimulates bacterial growth, causing carbon emissions from soils to rise.

None of this is to suggest that the idea has no virtues; simply that they are outweighed by hazards, which the promoters have either overlooked or obscured. Nor does this mean that charcoal can't be made on a small scale, from straw or brashings or sewage that would otherwise go to waste. But the idea that biochar is a universal solution which can be safely deployed on a vast scale is as misguided as Mao Zedong's Great Leap Backwards. We clutch at straws (and other biomass) in our desperation to believe that there is an easy way out.

[Adrisya Alok]

I suspect that Lovelock was given advance copy of the Monibot piece, because there's already a well-written response up from him:

http://www.guardian.co.uk/environment/2 ... -earth-c02


James Lovelock on Biochar: let the Earth remove CO2 for us

James Lovelock: George Monbiot is wrong to dismiss biochar out of hand – burying carbon is one way to tackle climate change

I usually agree with George Monbiot and love the way he says it but this time – with his assertion that the latest miracle mass fuel cure, biochar, does not stand up – he has got it only half right.

Yes, it is silly to rename charcoal as biochar and yes, it would be wrong to plant anything specifically to make charcoal. So I agree, George, it would be wrong to have plantations in the tropics just to make charcoal.

I said in my recent book that perhaps the only tool we had to bring carbon dioxide back to pre-industrial levels was to let the biosphere pump it from the air for us. It currently removes 550bn tons a year, about 18 times more than we emit, but 99.9% of the carbon captured this way goes back to the air as CO2 when things are eaten.

What we have to do is turn a portion of all the waste of agriculture into charcoal and bury it. Consider grain like wheat or rice; most of the plant mass is in the stems, stalks and roots and we only eat the seeds. So instead of just ploughing in the stalks or turning them into cardboard, make it into charcoal and bury it or sink it in the ocean. We don't need plantations or crops planted for biochar, what we need is a charcoal maker on every farm so the farmer can turn his waste into carbon. Charcoal making might even work instead of landfill for waste paper and plastic.

Incidentally, in making charcoal this way, there is a by-product of biofuel that the farmer can sell. If we are to make this idea work it is vital that it pays for itself and requires no subsidy. Subsidies almost always breed scams and this is true of most forms of renewable energy now proposed and used. No one would invest in plantations to make charcoal without a subsidy, but if we can show the farmers they can turn their waste to profit they will do it freely and help us and Gaia too.

There is no chance that carbon capture and storage from industry or power stations will make a dent in CO2 accumulation, even if we had the will and money to do it. But we have to grow food, so why not help Gaia do the job of CO2 removal for us?

[arvmehta]

Consider grain like wheat or rice; most of the plant mass is in the stems, stalks and roots and we only eat the seeds. So instead of just ploughing in the stalks or turning them into cardboard, make it into charcoal and bury it or sink it in the ocean.

I am with Monbiot on this one and there are no silver bullets . A simple story I read , I don't remember the source though . When farmers in Southern India switched from traditional varieties of long stalked paddy to short stalk paddy there was a severe shortage of animal fodder which is usually the stalks of the rice plant . Due to this farmers had to resort to buying animal feed or let go of the livestock which in turn reduced the amount of cow dung available for use in the fields and so a greater reliance on chemical fertilizers . So the moral of the story is that any drastic changes to an established system is going to create stresses at various points on the system . Biochar might have its virtues but to propose something on this scale is just irresponsible .