“The regenerative qualities identified in prehistoric, anthropogenic Amazonian dark earths suggest that notoriously infertile tropical soils can be greatly improved. Soil enhancement practices by ancient Amerindians allowed them to intensively cultivate the land, without needing to continually clear new fields from forest. As increasing populations place ever greater pressure on tropical forests, this legacy of rich, ‘living’ soils warrants further study in the search for high-yield, land intensive, yet sustainable forms of management.” — From Amazonian Dark Earths: Explorations in Space and Time.

These project posts and updates from the summer 2008 section of HU2506 — Humanities, Technology & Society—are authored by participants in our Biochar @ MTU Project. The course and the project explore the concept of sustainability in its economic, social, cultural, and environmental forms before turning our attention to one scientific process in particular: creating biochar, a process that results in a carbon negative nutrient-rich soil amendment for community gardeners and farmers.

Biochar has a 5,000-year history as terra preta, or Indian black earths (terra preta de indio) in Amazonian South America and thus involves us right away in history, culture, geography, biology, and soil science. We explore those contexts while trying to create biochar and assess the longer-term feasibility of a community Keweenaw Biochar Project.

The number that tends to attract attention, inspire both optimism and skepticism, and send us all to our libraries, labs, and greenhouses is the preliminary data provided by Christoph Steiner:

That research is reported in Amazonian Dark Earths: Explorations in Space and Time (2004; p. 191) and more recently, in Slash and Char as Alternative to Slash and Burn (2007 ; p. 61). If you’re on or near the Michigan Tech campus, a copy of Slash and Char is available for review in 112 Walker Arts & Humanities.

As the Terra Preta @ MTU Working Group uses the fall semester to develop a mission and a research scope, and to build local community alliances, we focus on data and hypothesis such as Steiner’s to help frame a series of questions and projects:

• How should we contextualize that research for local and regional community members, farmers, and gardeners?
• How should we contextualize it as a way to learn about soil characteristics in the Upper Peninsula, regionally, and globally?
• How should we contextualize it for Michigan Tech faculty and graduate students in soil science, chemistry, environmental engineering, forestry, and humanities as a way to develop collective expertise?
• How should we contextualize it for possible fundraising and grant opportunities?
• What role can the working group play in local and regional efforts to understand terra preta (broadly) and biochar (specifically)?
• Where does terra preta fit in environmental, social, cultural, and manufacturing notions of “sustainability”?
• And on particularly reflective and socially aware days: what is the relationship between hip-hop culture, sustainability, and the environment?

We currently think of terra preta, or terra preta de indio as a framework for exploring the historical, archeological, anthropological, scientific, and indigenous aspects of “dark earth.” We think of biochar as a process and product that may be used as a soil amendment; that it may help increase soil fertility dramatically; and that it may help mitigate climate change via its carbon-negative sequestration qualities.

If you are interested in joining this university and community effort — as a community member, as a student, staff, or faculty member — write to Michael and we will add you to our biochar-l mailing list and update you on future plans.

Carbon sequestration in soil also has significant potential. Biochar, produced in pyrolysis of residues from crops, forestry, and animal wastes, can be used to restore soil fertility while storing carbon for centuries to millennia. Biochar helps soil retain nutrients and fertilizers, reducing emissions of GHGs such as N2O. Replacing slash-and-burn agriculture with slash-and-char and use of agricultural and forestry wastes for biochar production could provide a CO2 drawdown of ~8 ppm or more in half a century.

The full report can be found here: www.columbia.edu/~jeh1/2008/TargetCO2_20080407.pdf

The September 2008 issue of National Geographic has an article on soil that contains an extended discussion of biochar — beginning on page 7 [of 9]:

Sombroek had wondered if modern farmers might create their own terra preta—terra preta nova, as he dubbed it. Much as the green revolution dramatically improved the developing world’s crops, terra preta could unleash what the scientific journal Nature has called a ‘black revolution’ across the broad arc of impoverished soil from Southeast Asia to Africa.

Key to terra preta is charcoal, made by burning plants and refuse at low temperatures. In March a research team led by Christoph Steiner, then of the University of Bayreuth, reported that simply adding crumbled charcoal and condensed smoke to typically bad tropical soils caused an ‘exponential increase’ in the microbial population—kick-starting the underground ecosystem that is critical to fertility.

The process is attracting the attention of community members, soil scientists, organic gardeners, and environmental engineers, as it has been shown to be both a carbon-negative soil amendment that helps to mitigate climate change and it has the potential to dramatically increase soil fertility. These images represent our process or replicating previous community efforts; although larger-scale initiatives are underway internationally, we focus on what local gardeners and small farmers might attempt here in the Houghton and Keweenaw area.

“Researchers trying to replicate the fertility of terra preta have concluded that its secret is in the charcoal. Work by soil scientists like Laird, Johannes Lehmann of Cornell, and Mingxin Guo of Delaware State University suggests that the benefits of supplementing soil with charcoal – which they call ‘biochar’ to distinguish it from the fuel of backyard barbecues – could be dramatic, widespread, and durable.”

“Biochar, they have found, enhances the retention of water and nutrients, decreases the need for fertilizer, encourages microbial growth, and allows more air to reach crop roots. It also breaks down at a far slower rate than traditional fertilizers and soil additives.”

Depending on how the charcoal is made and applied, estimates of its life span range from decades to millennia. Scientists believe that some Amazonian terra preta soils are at least 2,000 years old. ‘Biochar is much more effective at doing all the great things that normal organic matter usually does in soil, but it does it in much more effective ways, and it does it in a much longer way,’ says Lehmann.”

Soil scientists have been experimenting with biochar for just a few years – barely enough time to see how well it performs over repeated plantings. Even its champions concede that there’s plenty we need to learn about how to produce it on a mass scale. Researchers today are looking at how it might best be applied to the soil: in a dust, perhaps, or in pellets, or in a slurry mixed with manure. Two American companies, Eprida and BEST Energies, are working on bringing it to market.

In addition to the garden and small-farm applications we’ve been considering for biochar, one of the scientific appeals of biochar is its potential to help mitigate global warming by sequestering carbon that would otherwise be released into the atmosphere. A new book — Slash and Char as Alternative to Slash and Burn — discusses the science behind biochar in some detail:

Energy and agricultural systems based on biochar could help tackle four of the world’s most pressing issues all at once:

• they could allow resource poor farmers in the tropics to improve agricultural yields considerably and thus fight poverty and food insecurity;
• they can reduce global carbon emissions on a massive scale by creating a stable carbon sink: as plants take CO2 from the atmosphere, store it in their tissue and are then turned into biochar sequestered in soils, the carbon stays locked up for centuries, possibly millenia;
• they allow for the production of renewable carbon-negative bioenergy, either in the form of electricity or liquid fuels, and can thus bring energy to millions of the world’s rural households who currently lack access to modern energy;
• they could become one of the keys to slowing tropical deforestation – itself a major source of greenhouse gas emissions – by prompting millions of shifting cultivators to change their current practise of ’slash and burn’ agriculture to ’slash and char’ instead. Shifting cultivation is caused by the rapid depletion of soils, forcing farmers to clear forest for new land every few years; in contrast, biochar amended soils would boost soil fertility, bring the farmers higher yields, thus limiting their need to take new land into cultivation.

Other readings that specifically address the potential for mitigating climate change from biochar development and use:

Lehmann, Johannes. “Biochar for mitigating climate change: carbon sequestration in the black.” FORUM GEOÖKOL. 18 (2), 2007.

Lehmann, J., Gaunt, J. and Rondon, M. (2006); “Bio-char sequestration in terrestrial ecosystems – a review”, Mitigation and Adaptation Strategies for Global Change, 11, 403–427.

Lehmann, J., “Bio-energy in the black.” Front Ecol Environ 2007; 5(7): 381–387.

At best, common renewable energy strategies can only offset fossil fuel emissions of CO2 – they cannot reverse climate change. One promising approach to lowering CO2 in the atmosphere while producing energy is biochar bio-energy, based on low-temperature pyrolysis. This technology relies on capturing the off-gases from thermal decomposition of wood or grasses to produce heat, electricity, or biofuels. Biochar is a major by-product of this pyrolysis, and has remarkable environmental properties. In soil, biochar was shown to persist longer and to retain cations better than other forms of soil organic matter.

Periman, Richard D. “Visualizing the Anthropocene: Human Land Use History and Environmental Management.” USDA Forest Service Proceedings RMRS-P-42CD. 2006.

“Significant Climate Mitigation Is Available from Biochar.”
IGSD/INECE Climate Briefing Note: 10 July 2008.