Biochar research rooted in ancient history
By Jean Caspers-Simmet
simmet@agrinews.com
Date Modified: 07/29/2010 9:45 AM
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AMES, Iowa — The story of biochar begins in the 1500s when Francisco de Orellana reported seeing a vast civilization as he sailed down the Amazon. Within 50 years the civilization had vanished and for the next 500 years people discounted his account.
That changed in the 1960s when archaeologists digging in the Amazon found dark, rich Terra Preta soils adjacent to low productivity Oxisol soils.
What accounted for the soil differences was a civilization dating back 3,000 years that used a practice called slash and char as it cut the Amazon forests. Trees were cut, started on fire and buried. The product of that process was char.
"Today, 500 years later, there are thousands of hectares of these prized soils," said David Laird, a soil scientist with the USDA/ARS National Laboratory for Agriculture and the Environment at Iowa State University.
In the 1970s and 80s, soil scientists starting looking at these unique soils, but it was the late 1990s before they understood that it was a type of charcoal that enriched the soils.
"There's been an explosion of research and the vision has evolved that we don't have to let the quality and productivity of our soils degrade, that we can actually increase productivity," Laird said.
With growing interest in bioenergy, "the light bulb flashed," Laird said. Bioenergy and biochar can work together.
Robert Brown, director of Iowa State University's Bioeconomy Institute, is adapting fast pyrolysis, a process where biomass crops when heated in the absence of oxygen decompose into syngas, bio-oil and biochar. Fast pyrolysis takes a few seconds compared to the days-long method used for centuries to make charcoal. In that process the oil escaped into the environment as smoke.
Last week, ISU hosted the U.S. Biochar Initiative Conference. At the conference scientists, farmers, environmental advocates, industry representatives and entrepreneurs talked about the latest science and practices for all aspects of the biochar value chain, said Jill Euken, deputy director of the Bioeconomy Institute. Prior to the conference, the researchers met with the news media to discuss ISU's biochar research.
Biochar is filled with tiny holes that hold water and provide habitat for micro-organisms, Laird explained. Soil amended with biochar has increased capacity to hold water and nutrients.
Biochar is an extremely stable source of carbon, Laird said. Corn stover, when buried in the soil, essentially decomposes within four to five years. Biochar has a half life of over 1,000 years.
Laird and other USDA/ARS scientists are studying how biochar interacts with soil. At ISU's Ag Engineering and Agronomy Research Farms west of Ames, they applied 0, 4.4 and 8.2 tons per acre of biochar to plots in 2007. In 2008, a challenging year, the trial showed a 15 percent increase in plant populations and a 4 percent increase in corn grain yield. In 2009, a better year, there was little effect.
"Where we see a big crop response is on degraded soils," Laird said. "Iowa soils for the most part are already highly productive, but it is degraded soils where there is an opportunity to improve."
Laird has a plot demonstrating how biochar improves degraded soil. In a field along Highway 30 there is an area where the Iowa Department of Transportation disturbed the soil for a road project. Flooded several times, the ground is wet, compacted and lacks organic matter.
"It's the worst place we could find," Laird said. "Where we applied 30 to 40 tons of biochar, the corn is green and tall. The other corn is yellow and stunted."
Laird and Brown have a vision of local, co-op-scale fast pyrolyzers that turn biomass into bio-oil, a renewable energy product, and biochar, a soil amendment that builds soil quality, increases crop yields and sequesters carbon in the soil for 1,000 years. It benefits the local economy and the environment.
"There are a lot of benefits at the community level," Laird said.
Brown has experimented with biochar on the square-foot garden he built for his wife. He saw increased vegetable production ranging from 15 percent for spinach to 300 percent for bok choy.
Brown and Laird cautioned that more research is needed. Standards must be established. In its current state, biochar can be a fire hazard and it is extremely dusty.
"This isn't ready for prime time yet," Laird said.