Building a world of
resilient communities.

MAIN LIST

 

Terra Preta: black is the new green

This piece was originally published on Worldchanging.com, "the world's leading sustainability blog."


Terra PretaCarbon 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.

Amazonian Dark Earth, or terra preta do indio, has mystified science for the last hundred years. Three times richer in nitrogen and phosphorous, and twenty times the carbon of normal soils, terra preta is the legacy of ancient Amazonians who predate Western civilization. Scientists who long debated the capacity of 'savages' to transform the virgin rainforest now agree that indigenous people transformed large regions of the Amazon into amazingly fertile black earth. The Amazonians' techniques remain an enigma but are believed to have used slash-and-smolder to lock half of the carbon in burnt vegetation into a stable form of biochar instead of releasing the bulk of it into the atmosphere like typical slash-and-burn practices.

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!

Indeed, there is profit to be made in this black earth, for if green is the new black, then black could be the new green. 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-Troupsch gas-to-liquids diesel (BTL diesel), as well as the ammonia used to enrich the carbon to make ECOSS fertilizer.

We don't maximize for hydrogen; we don't maximize for biodisel; we don't maximize for char...By being a little bit inefficient in each, we approximate nature and get a completely efficient cycle.

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.

How ironic it is that ancient humans cultivated the very fertility of Earth's most pristine places so seamlessly as to be nearly invisible. Perhaps then our challenge as planetary gardeners is not to preserve nature in a bubble but to reweave ourselves into it-to invert our footprints into handprints.

(Thanks, Garry!)

Editorial Notes: Re-posted with permission. Related articles: Putting the carbon back: black is the new green (Nature 10 August 2006 - now online):
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.
Terra Preta de Indio (soil biogeochemistry, Johannes Lehmann of Cornell U.) Soil Improvment and Carbon Sequestration (PDF - attractive factsheet from Johannes Lehman) Amazon rainforest civilization (Chronicle of Higher Education)

What do you think? Leave a comment below.

Sign up for regular Resilience bulletins direct to your email.

Take action!  

Make connections via our GROUPS page.
Start your own projects. See our RESOURCES page.
Help build resilience. DONATE NOW.

Tags:  

Greening Philly’s vacant lots

Community access to vacant land has the potential to reduce crime rates in …

Redefining Local

What does “local” mean when you live on a remote farm or ranch?

Local Food is Not a Local Food System

Many people are now familiar with the phrase “farm-to-fork” but …

The Final Word on Food Banks?

Every week, in Britain and across the world, new food banks are opening …

Joy Carey explains Bristol's progressive food culture

Bristol is the first UK city to have its own Food Policy Council. Joy Carey …

IYFF:Muckleshoot Food Sovereignty Initiative promotes community-based tribal food system development

The Muckleshoot Tribe, along with a number of other Puget Sound tribes in …

Paying for our cheap food choices

‘How can anyone say that food is too cheap when food prices are …