"Black Gold Agriculture" — May Revolutionize Farming, Curb Global Warming


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    Credit: Courtesy of Mingxin Guo

    The raw materials involved in the production of biochar.

Newswise — 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.

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.

The American Chemical Society — the world's largest scientific society — is a nonprofit organization chartered by the U.S. Congress and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.

Note for reporters' use only: For full information about the New Orleans meeting, including access to abstracts of more than 9,000 scientific papers and hundreds of non-technical summaries, visit http://www.eurekalert.org/acsmeet.php.

The paper on this research, CELL 272, will be presented at 1:30 p.m. on Thursday, April 10, at the Morial Convention Center, Room R07, during the symposium, "Renewable Chemicals from Plant and Animal-Based Agricultural Wastes"

Mingxin Guo, Ph.D., is an Assistant Professor in the Agriculture and Natural Resources Department at Delaware State University in Dover, Delaware.

ALL PAPERS ARE EMBARGOED UNTIL DATE AND TIME OF PRESENTATION, UNLESS OTHERWISE NOTED The paper on this research, CELL 272, will be presented at 1:30 PM, Thursday, April 10, 2008, during the symposium, "Renewable Chemicals from Plant and Animal-Based Agricultural Wastes." CELL 272Application of organic wastes-derived charcoal for soil quality improvement Program Selection: Division of Cellulose & Renewable MaterialsTopic Selection: Renewable Chemicals from Plant and Animal-Based Agricultural Wastes

AbstractSoil quality deterioration caused by depletion of organic matter in agricultural land as a result of chemical fertilization, harvesting deprivation, and mechanical manipulation is a worldwide issue. Fertilization of farmland with raw plant debris has failed to persistently elevate and maintain soil organic matter, since the applied raw organic residues are mineralized rapidly in the field. This study explored the feasibility of applying degradation-resistant charcoal derived from organic wastes to cropland for long-term soil quality improvement. A wide range of organic wastes including plant residues and animal wastes were converted into charcoal by smoldering. Soils were amended with organic wastes-derived charcoal and were examined for quality improvements in porosity, water holding capacity, water permeability, nutrient retention, and nutrient availability. Greenhouse potting experiments were conducted to determine practical application rates of charcoal in soil amendment. The results demonstrate that charcoal amendment is a revolutionary approach for long-term soil quality improvement. ________________________________________Researcher Provided Non-Technical Summary Briefly explain in lay language what you have done, why it is significant and what are its implications (particularly to the general public)

Organic matter is a very important component of soil. Soils low in organic matter (e.g. <3%) are generally poor, dense, lack of earthworms, and do not have the ability to hold enough water and nutrients. Adding compost, animal manure, or leaving crop residues in the field cannot consistently increase soil organic matter content, because the added organic materials are quickly decomposed to carbon dioxide. In this study, we applied charcoal generated from tree leaves, corn stalk, wood chips, and poultry litter to permanently increase soil organic matter content and improve soil quality. Charcoal is very stable and will exist in soils for hundreds to thousands of years. More important, charcoal is porous and has high nutrient and water holding capacities. We found that soils receiving charcoal were much looser, adsorbed significantly more water and nutrients, and produced higher crop biomass. The results suggest that charcoal may be an excellent material for long-term soil quality improvement. In addition to persistently enhancing soil quality, charcoal fertilization also improves water quality by reducing nutrient loads and mitigates global warming by transferring carbon from the air to soil.

How new is this work and how does it differ from that of others who may be doing similar research?

This is a new and pioneer study. Systematic investigation of soil quality improvement by charcoal fertilization has not been reported. Similar research indicates that charcoal addition increased soil nutrient holding capacity, enhanced crop yield, and promoted nitrogen biofixation in poor soils.

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