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Biochar: a brief history and developing future

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. 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 …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.

Biochar – charcoal produced from pyrolysis of biomass – has received tremendous attention and support in recent years, and championed as one of the potentially most useful techniques for soil restoration and carbon sequestration in the modern era. Although a multitude of initiatives in biochar research and application have sprung into action many critical details remain uncertain.

Fortunately, the production and soil effects of biochar have a lengthy historical precedent as well as a remarkable ease of global distribution. These factors, combined with collaborative biochar databases, online forums, and outreach projects provide the foundation for what may rapidly become a breakthrough trend in ecological investigation and environmental restoration: do-it-yourself adaptation to 21st century global change issues.

The use of biochar for soil nutrient retention and improvement is thought to have originated over 2,000 years ago in the Brazilian Amazon. Archeological studies indicate populations of native Amazonians prospered in agrarian civilizations sustained by amending nutrient-poor tropical soils with application of charcoal (aka biochar) and organic matter. These populations appear to have flourished from a period between 400 BC until they were decimated by pandemic introduced by Spaniard expeditions as recently as 500 years ago.

Amazonians were believed to have produced biochar by igniting then burying and smoldering biomass to create the low-oxygen conditions necessary for the creation of charcoal. This technique is known as slash-and-char agriculture and results in as much as 50% carbon sequestration, as opposed to slash-and-burn methods which yield higher levels of ash and only 1% to 3% carbon sequestration.

In the mid 1500’s, Spanish explorer Francisco de Orellana led several hundred infantrymen and horsemen into the deltas of the Brazilian Amazon (Xingu) with the purpose of establishing settlements within the mouth and interior of the river. Orellana reported an advanced civilization thriving in the Amazon region at the time. Evidence of geoglyphs and extensive terra preta (biochar) amended soils dating between 0-1250 AD support Orellana’s claims. Contemporary archaeological investigations led by Michael Heckenberger and Eduardo Goes Neves have exposed remnants of ancient cities, 60 foot wide “highways,” and soils made fertile by biochar in regions of the Amazon visited by Orellana’s expedition. A population of about 5 million is believed to have been thriving in the area in 1500 AD, reduced by pandemic to 1 million by 1900 and less than 200,000 by the 1980s.

At present, thousands of hectares of anthropogenic, nutrient-rich biochar soils remain in the Xingu region of the Amazon, distinguished from the generally depleted tropical soils. These unique soils have provided scientists, horticulturalists and environmentalists with evidence of the enduring beneficial effects of biochar and verified it as a stable, sequestered form of carbon with the potential to mediate modern greenhouse gases concentrations.

The image above at the left is a large strangler fig tree near Puerto Jimenez, Costa Rica. Many trees and plants of the new world tropics have adapted to the typically nutrient-poor, highly-weathered tropical soils by creating complex root structures and buttresses that extend in wide yet shallow areas around the central trunk. Since the vast majority of plant-available nutrients in tropical forests tend to be located in the upper layer of the soil, these adaptations allow plants to support large structures without extending deep roots. When a tropical forest is destroyed or degraded, the loss of constant input of fresh biomass renders the soils infertile. Biochar amendments to these soils offer a range of long lasting benefits and generally support increased productivity. The image to the right of the strangler fig compares a typical nutrient-poor reddish tropical soil (oxisol), contrasted on the right with a darker, more fertile biochar-amended oxisol.

The archaeological discoveries of the Amazonian tribes and terra preta soils suggest fascinating connections between historical applications of biochar in non-hierarchical, persistent complex human societies, presenting compelling possibilities for present-day models of networked resilient techniques. Author and biochar advocate James Bruges recognizes the link between fertile soils and non-hierarchical complex human societies in his text, “The Biochar Debate.” Bruges comments on Orellena’s observations, writing, “In this and other descriptions there is no mention of pyramids as in the Maya civilization, no ramparts, no hierarchy of grand buildings surrounded by hovels. Is it too much to speculate that the abundant soil fertility did away with the need for a highly centralized authoritarian society?”

Just as stable, fertile soil may have bolstered the framework of past decentralized societies, biochar and improved agricultural techniques are useful for individuals, small groups and resilient communities seeking food independence.

The technical expertise needed to create and apply biochar in soil amendments, bioremediation, and carbon sequestration is minimal and may be easily researched and instructed through online forums, community seminars and outreach projects. Modern human populations may be able to harness many of the advantages of biochar to regain elements of freedom from inefficient, unsustainable industrial and commercial agricultural practices.

A prototype of UIRI’s biochar stove with thermoelectric generator.
A prototype of UIRI’s biochar stove with thermoelectric generator.

Biochar applications have been tested in a variety of soils and climates, commonly demonstrating positive effects in a wide range of global ecosystems. In degraded soils of Midwest North America, for instance, researchers at Iowa State University’s Agricultural Engineering Research Farms report increased crop yield with the use of biochar. The Uganda Industrial Research Institute (UIRI) in conjunction with the China Bamboo Research Center (CBRC) have noted positive results in plant productivity in nutrient poor soils with biochar from agricultural waste and excess bamboo. UIRI and CBRC projects in Uganda have developed biochar stoves capable of generating electricity and heat, while reducing smoke and pollution typical to wood burning stoves.

Biochar production offers a wide range of economic and environmental benefits in three major categories:

  1. Reduction of greenhouse gases – many of the details of biochar’s ability to retain carbon in inactive sinks for thousands of years and to suppress soil emissions of potent greenhouse gases, including nitrous oxide and methane, have been scientifically reviewed and substantiated. The complex, systemic nature of climate change, however, necessitates much deeper levels of experimentation and collaboration. Biochar may prove to be one of the most useful techniques in carbon sequestration but must be combined with enormous efforts to reduce emissions.
  2. Soil amendment – includes restoration of impoverished soils, nutrient retention, and bioremediation. Biochar has shown positive results in the remediation of heavy metal toxins, fertilizer runoff, petroleum spills, polycyclic aromatic hydrocarbons (PAHs), and a variety of revegetation processes.
  3. External effects and bi-products of pyrolysis – reduction of pollution from wood-burning stoves, generation of heat, production of biofuels. A wide range of biochar processors and prototypes have been developed to harness a variety of the beneficial side streams of production. Most of these designs are freely available online and relatively easy to build.

For more information regarding biochar’s applications in developing communities, I consulted Seattle Biochar Working Group (SeaChar) co-founder and President Art Donnelly. Donnelly has over 20 years of experience working with custom metal design, and holds a BFA degree from the University of Washington and an MFA degree from Rhode Island School of Design. Working with coffee farmers in Costa Rica, SeaChar launched the Estufa Finca (“Farm Stove”) project in January of 2010. The biochar producing Estufa Finca cook-stove was initially designed by Donnelly for use by the migrant coffee bean-pickers, living in migrant farm-workers camps. All of the project’s stoves are built in Costa Rica using local materials. The past two years has seen a constant process of stove refinements. To date the Estufa Finca team of partners has been involved in building and distributing 260 Estufa Finca cook-stoves.

With a local women’s group now building and distributing stoves in coffee country, SeaChar’s focus has shifted to the Talamanca region of South East Costa Rica.

SeaChar’s Art Donnelly elaborates on the details of the project:

We are now working with the indigenous Bribri cacao and banana farmers of this area. The opportunity to work with a resident population living in their own homes has allowed us to do more in depth field testing of our innovative community based approach to promoting the stoves, how to support new stove users, and building a market value for the biochar the stoves produce. A 2011 grant from National Geographic has allowed us to hire and train local community stove promoters to sell stoves and teach their neighbors how to use them. Our new stove owners are offered the opportunity to participate in our biochar “buy-back” program. Some of our cooks are earning an extra $30 a month, by saving and selling us their biochar.

In the first 5 months of this program we have collected over two tons of high quality biochar from stove users. The biochar we are buying is being used in ongoing plot and pot-testing with our University and commercial nursery partners, some has been donated to two local school garden projects that we are working with and more has been used in our ongoing series of biochar workshops for farmers. We are also now selling biochar to a small number of nurseries and organic producers.

On a particularly gratifying day in the pueblo of Suretka recently, I was at the home of the family who would soon be hosting the upcoming round of cooks’ training workshops. Don Daniel, the grandfather of the household, has been a cacao farmer for nearly 60 years. Don Daniel had attended one of our biochar workshops for farmers. He saw one of our 55-gallon drum biochar kilns demonstrated. Don Daniel invited me back to his garden where he proudly showed me the copy of our kiln, which he had built from a good memory and available scrap. The char in his raised beds showed he was getting good use out of it.

SeaChar is also working with the Center for Tropical Agricultural Investigation and Education (CATIE) on a multi-year study of the effect of biochar on banana and cacao cultivation. Brazilian graduate student Julliano Hojah da Silva has been the lead researcher this past year. Among the hypotheses we are testing is that the application of biochar around the drip line of trees can reduce the incidence of

fungal disease in organic cacao. We will be releasing Juliano’s 1st year data in mid-December. Preliminary results look promising. Testing with biochar and bananas will begin in 2013. Biochar and biochar technology represent a powerful new development platform. However, for these concepts to become reality a family of simple, elegant and durable tools must be developed and tested in the real world. SeaChar is co-creating this technology in the field with local partners. We plan to share the lessons we learn here as widely as possible.

Large-scale biochar production through cogeneration projects represents a very real investment opportunity. Costa Rica’s economically important high-end export crops like coffee, cacao,

bananas, and pineapple need both effective organic soil amendments as well as clean burning biomass heat. Growth in demand for premium organic product is exceeding the capacity of the region’s producers. A major limiting factor is the current lack of effective organic soil amendments and fertilizers. Charcoal is already in demand for use in the enzyme-rich compost known as bokashi. The challenge will be to

differentiate biochar, which will need to sell at a higher per kilogram price, from the fines left over from traditional charcoal making.

At the same time a changing climate is driving the increased demand for heat energy to dry commodities like coffee and cacao beans. For agricultural producers like our partner APPTA (1200 member organic growers association) the lack of cost effective, environmentally sustainable drying technology is a major constraint on production.

SeaChar’s integrative approach to biochar exemplifies its usefulness in socially and environmentally conscious system design, combining soil restoration with scientific research in bioremediation, agricultural amendment, carbon sequestration, economic opportunities and the vast potential for further development.

Biochar organizations featuring DIY production information may be found through the following links:




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