“Black Gold Agriculture” May Revolutionize Farming, Curb Global Warming
Fifteen hundred years ago, tribes people from the central Amazon basin mixed their soil with charcoal derived from animal bone and tree bark. Today, at the site of this charcoal deposit, scientists have found some of the richest, most fertile soil in the world. Now this ancient, remarkably simple farming technique seems far ahead of the curve, holding promise as a carbon-negative strategy to rein in world hunger as well as greenhouse gases.
At the 235th national meeting of the American Chemical Society, scientists report that charcoal derived from heated biomass has an unprecedented ability to improve the fertility of soil — one that surpasses compost, animal manure, and other well-known soil conditioners.
March 10, 2008 Biopact, a leading bioenergy web site, has announced the creation of a “Biochar Fund” to help poor farmers improve their quality of life without hurting the environment. Biochar — a farming technique that adds charcoal obtained from the pyrolysis of biomass to poor, acidic soils — has been hailed as a way to simultaneously sequester atmospheric carbon and improve soil fertility. By intensifying agricultural productivity, biochar could help reduce the need to clear forests and ecosystems for cropland while offering farmers diversified income through carbon credits.
February 21, 2008 Restoring the ability of soil to store carbon by promoting native grasses and vegetation can help reverse global warming, desertification and biodiversity loss, says an Australian researcher. Land use change — including deforestation, bush fires, and soil degradation — accounts for roughly 20 percent of global greenhouse gas emissions, but land management practices can be used to reduce emissions. While reforestation and avoided deforestation have garnered a lot of attention of late, restoration of other forms of vegetation can dramatically increase the capacity of degraded landscapes to store carbon.
May 17, 2007 Terra preta, the ancient charcoal-based soil used by ancient Amazonians to create permanently fertile agricultural lands in the rainforest, is getting serious consideration as a means to fight global warming and meet domestic energy demand, reports an article in Scientific American.
October 17, 2005 Controversial evidence uncovered over the past decade suggests that the Amazon rainforest was once home to large sedentary populations of people. Besides the well-known empires of the Inca and their predecessors, the Huari, millions of people once lived in the forests and shaped the environment to suit their own needs.
They also suggest that this so-called “biochar” profoundly enhances the natural carbon seizing ability of soil. Dubbed “black gold agriculture,” scientists say this “revolutionary” farming technique can provide a cheap, straight-forward strategy to reduce greenhouse gases by trapping them in charcoal-laced soil.
“Charcoal fertilization can permanently increase soil organic matter content and improve soil quality, persisting in soil for hundreds to thousands of years,” Mingxin Guo, Ph.D., and colleagues report. In what they describe as a “new and pioneering” ACS report — the first systematic investigation of soil improvement by charcoal fertilization — Guo found that soils receiving charcoal produced from organic wastes were much looser, absorbed significantly more water and nutrients and produced higher crop biomass. The authors, with Delaware State University, say “the results demonstrate that charcoal amendment is a revolutionary approach for long-term soil quality improvement.”
Soil deterioration from depletion of organic matter is an increasingly serious global problem that contributes to hunger and malnutrition. Often a result of unsustainable farming, overuse of chemical fertilizers and drought, the main weapons to combat the problem —compost, animal manure and crop debris — decompose rapidly.
“Earth’s soil is the largest terrestrial pool of carbon,” Guo said. “In other words, most of the earth’s carbon is fixed in soil.” But if this soil is intensively cultivated by tillage and chemical fertilization, organic matter in soil will be quickly decomposed into carbon dioxide by soil microbes and released into the atmosphere, leaving the soil compacted and nutrient-poor.
Applying raw organic materials to soil only provides a temporary solution, since the applied organic matter decomposes quickly. Converting this unutilized raw material into biochar, a non-toxic and stable fertilizer, could keep carbon in the soil and out of the atmosphere, says Guo.
“Speaking in terms of fertility and productivity, the soil quality will be improved. It is a long-term effect. After you apply it once, it will be there for hundreds of years,” according to Guo. With its porous structure and high nutrient- and water-holding capabilities, biochar could become an extremely attractive option for commercial farmers and home gardeners looking for long-term soil improvement.
The researchers planted winter wheat in pots of soil in a greenhouse. Some pots were amended with two percent biochar, generated from readily available ingredients like tree leaves, corn stalk and wood chips. The other pots contained ordinary soil.
The biochar-infused soil showed vastly improved germination and growing rates compared to regular soil. Guo says that even a one-percent charcoal treatment would lead to improved crop yield.
Guo is “positive” that this ground-breaking farming technique can help feed countries with poor soil quality. “We hope this technology will be extended worldwide,” says Guo.
“The production of current arable land could be significantly improved to provide more food and fiber for the growing populations. We want to call it the second agricultural revolution, or black gold revolution!”
He suggests that charcoal production has been practiced for at least 3000 years. But until now, nobody realized that this charcoal could improve soil fertility until archaeologists stumbled on the aforementioned Amazonian soil several years ago.
Biochar production is straightforward, involving a heating process known as pyrolysis. First, organic residue such as tree leaves and wood chips is packed into a metal container and sealed. Then, through a small hole on top, the container is heated and the material burns. The raw organic matter is transformed into black charcoal. Smokes generated during pyrolysis can also be collected and cooled down to form bio-oil, a renewable energy source, says Guo.
In lieu of patenting biochar, Guo says he is most interested in extending the technology into practice as soon as possible. To that end, his colleagues at Delaware State University are investigating a standardized production procedure for biochar. They also foresee long-term field studies are needed to validate and demonstrate the technology. Guo noted that downsides of biochar include transportation costs resulting from its bulk mass and a need to develop new tools to spread the granular fertilizer over large tracts of farmland.
The researchers are about to embark on a five-year study on the effect of “black gold” on spinach, green peppers, tomatoes and other crops. They seek the long-term effects of biochar fertilization on soil carbon changes, crop productivity and its effect of the soil microorganism community.
“Through this long-term work, we will show to people that biochar fertilization will significantly change our current conventional farming concepts,” says Guo.