By Albert Bates. Gabriola Island, BC, Canada: New Society Publishers, 2010.
“Biochar” is charcoal—a substance made by burning wood or other organic matter in the absence of oxygen.
We are in big trouble from our violent relationship with the Earth. We risk runaway climate change. Biochar to the rescue? Of course not. Sorry. We know perfectly well there is no one solution, nothing that will absolve us from the challenge of working out how to live with less and then no fossil fuel. That is our duty to the Earth and our offspring.
But biochar may play a modest but significant role in bringing carbon back down enough for human civilization to continue. Albert Bates’s book does a splendid job of telling us how this could be done, and covering who is doing what in this arena. Bates has impressive credentials for exploring alternatives to our current suicidal patterns. He shared the 1980 Right Livelihood Award for work to preserve the cultures of indigenous people and is co-founder of the Global Ecovillage Network, which he represents at the UN climate change talks. He is a practical man who has made and used biochar himself. And he is a good storyteller.
His book is full of fascinating stories—of the discovery of Amazonian biochar, and of the many people who have followed up on this. The book is fun to read. In addition, Bates does a good job of explaining the science behind charcoal, the nature of soil, and climate change.
Here’s the plot. About 10,000 years ago, agriculture began in the Fertile Crescent. The technology of ploughing and irrigating the soil were steadily refined.
These were wrong turns for humanity. The ploughing depleted the soil and the irrigation salinated the soil. Over time, the Crescent became a desert, and the civilizations that once flourished there disappeared. This story has repeated itself on most continents. Australia’s Murray River basin tragedy is the latest episode.
In two places agriculture took a different turn. In China, extensive composting returned to the soil what was taken out, even to the extent of routinely taking the humanure from cities back to the fields. Forty centuries later, the soil continued to be fertile.1 In Amazonian South America, a pattern of composting incorporating charred biomass developed. Bates believes it was sytematic, done to a recipe. The soil remains highly fertile, much more so than the surrounding rain forest soil, to this day, and even “grows,” apparently drawing nutrients to the soil from the surrounding area. When rediscovered last century, it came to be known as “terra preta”—black earth. Bates cites recent archaeological evidence of the remarkable population density of pre-Columbian Amazon civilization, supported by this soil. When that civilization fell suddenly after Spanish and Portuguese contact, their agricultural methods and the adapted plant varieties they had cultivated perished too, along with the formula for terra preta.
Other early agricultural and pastoral practices began to increase atmospheric carbon dioxide long before the fossil fuel age. Flooded rice paddies produced methane, as did increasing flocks of domesticated animals. Burning forest areas to clear land produced carbon dioxide and decreased the carbon dioxide “sink” capacity of the disappearing forest. By 1000 CE, most of England’s trees were cut down. By taking off crop after crop and dispersing the biomass, soil carbon decreased by 30-50 percent in most places, thus increasing carbon in atmosphere and ocean. In our reasonable focus on the role of fossil fuel in climate change, we tend to ignore the contribution of land use and change in land use, such as deforestation, in sending carbon into the atmosphere. It is perhaps responsible for a third of the excess greenhouse gases.
After 6000 years of ploughing we are relearning how to grow food while maintaining the health of the soil, including its crucial carbon content. We need to change our patterns of land use and agriculture urgently in ways that sequester carbon in stable form. It can be expected to remain sequestered in this form for centuries or millennia, and this is a vital parameter in the dynamics of the carbon cycle. In fact, the potential of massive programs of soil and biomass carbon sequestration could make a difference to atmospheric carbon in the next two decades—a time scale much faster than the probability of effective action from technologies now being invested with questionable hope, such as new fuels and carbon capture at source.
So-called “carbon farming” involves no tillage of the soil. It also involves organic growing methods, using crop residue as mulch (thus returning its carbon and other nutrients to the soil), and cover crops between the food or fibre crops. It involves rotational grazing of pasture animals, turning from annual crops to perennial polycultures, agroforestry, leaving wild plant strips, keyline water management, and subsoil ploughing. And it involves incorporating biochar mixtures, creating terra preta-type soil. These methods also have the potential to eliminate the use of nitrogen-based fertilizers—an important source of the potent greenhouse gas, nitrous oxide.
The program needs to involve massive global tree-planting, carbon farming and biochar sequestration, while stopping deforestation. Bates suggests that such “carbon farming” could sequester one gigatonne of carbon a year in both short-term and stable (long-term) carbon. Additional biochar use could sequester another gigatonne a year in stable carbon. Reforestation on a massive scale could sequester 4.5 gigatonnes a year. There are about 800 gigatonnes of carbon in the atmosphere, the vast majority of which is of natural origin; it flows into and out of the biosphere and oceans. Before the industrial age, these fluxes were in balance and the methods that we have been reviewing can bring them back into balance again, slowing and reversing the current disastrous accumulation of excess carbon. Merely by sustainably using biochar, an estimated maximum equivalent to 12 percent of current anthropogenic emissions can be removed per year.2
Bates tells us how biochar is made and why it works so well. There is a fascinating chapter on stoves, especially low-cost stoves to replace the smoky cooking methods responsible for a fair slice of low-income country mortality and morbidity. Some of these inventions also produce biochar which can increase garden fertility for the owners.
Bates doesn’t deal with the limits to biochar sequestration in soils with high carbon levels, or with the issue of loss of nutrients other than carbon in forming charcoal rather than letting biomass rot back into the Earth.
This book sent me into action—joining the International Biochar Initiative, and going to inspect our “terra preta”-enhanced tree plantings, which experts say are doing remarkably well. I like to think of the biochar around their roots, keeping carbon out of the atmosphere for centuries.
Joanna Santa Barbara is working to develop Atamai, a New Zealand ecovillage trying to respond to peak oil and climate change issues. She and her colleagues use a biochar mix in all their plantings.
1. FH King. Farmers of Forty Centuries: Organic Farming in China, Korea and Japan. Mineola, New York: Dover Publications, Inc., 2004. (First published in 1911.)
2. “Sustainable Biochar to Mitigate Global Climate Change,” by Dominic Woolf, James Amonette, F. Alayne Street-Perrott, Johannes Lehmann, and Stephen Joseph. Nature Communications, 1 (56) August 10, 2010.