Andy Clark wrote:
> -----Original Message-----
> From: ARS News Service [mailto:isnv@ars-grin.gov]
> Sent: Monday, May 17, 1999 10:18 AM
> To: ARS News List
> Subject: Farmers Part of the Global Warming Solution
>
> NEWS RELEASE:
> Farmers Now Part of the Global Warming Solution as U.S. Agriculture Becomes
> Net Carbon Sink
>
> -----------
> ARS News Service
> Agricultural Research Service, USDA
> May 17, 1999
> Don Comis, (301) 504-1625, dcomis@asrr.arsusda.gov
> -----------
>
> WASHINGTON, May 17, 1999--Sometime in the past 15 years, American farmers
> turned an environmental corner, Agricultural Research Service Administrator
> Floyd Horn announced today.
>
> "A dramatic change in tillage techniques shifted U.S. farm soils from net
> carbon dioxide producers to net accumulators of carbon--in the form of
> valuable soil organic matter. This makes their soils more productive and
> part of the potential global warming solution, rather than part of the
> problem," Horn said. "American farmers have virtually abandoned the
> moldboard plow used to break open the American West."
>
> Horn said that Raymond R. Allmaras, a soil scientist with the U.S.
> Department of Agriculture's Agricultural Research Service in St. Paul,
> Minn., made these findings after a thorough search of published reports and
> surveys for several major crops, comparing 1940 to 1990 conditions.
>
> "These reports showed that, in 1980, 75 to percent of American farmers were
> still using the plow. By 1993, a USDA survey showed that farmers used the
> moldboard plow on only 6 to 9 percent of corn, soybean, and wheat fields,"
> Horn said.
>
> Horn said Allmaras used yield records to estimate amounts of crop parts that
> would be left after harvest. "He also used long-term tillage experiments
> conducted by himself and ARS colleagues nationwide. Dale E. Wilkins, an ARS
> agricultural engineer in Pendleton, Oregon, assisted him in the study," Horn
> said.
>
> Allmaras said that one of his tillage experiments showed there was no carbon
> accumulation in soils during a 10-year period when corn and soybeans were
> planted after annual plowing; another showed that abandoning the moldboard
> plow produced distinct increases in soil carbon in as little as 10 years.
>
> "The soil is storing more carbon that otherwise might be in the atmosphere
> as carbon dioxide, which is one of the greenhouse gases thought to cause
> global warming," Allmaras said. "The plow lifts and inverts an 8 to 12-inch
> slice of soil, and also buries stubble and other unharvested crop residue
> that was once on or near the surface. That places the residue deep in the
> plow layer where different microbes live. These microbes convert the residue
> to a form of carbon that readily converts to CO2, which can escape to the
> atmosphere," he said.
>
> As farmers put aside the plow, they leave more residue on the soil or within
> a depth of 4 inches, Allmaras said. "For example, corn and grain sorghum
> farmers are returning about twice as much residue than in 1940, and they are
> keeping it on or near the surface. Here, the residue readily decays to
> valuable organic matter, a more stable carbon compound and a key component
> of the black, fertile prairie soil originally broken open by the plow. The
> moldboard plow robbed the soils of the increased organic matter offered by
> the yield increases since 1940," Allmaras said.
>
> Allmaras said the dramatic shift away from the moldboard plow has altered
> the farm landscape in another equally broad way: the reduced tillage and
> increased organic matter in the soil has led to a looser, less erodible soil
> that holds more water for crops. "This noticeable shift in the soil is the
> main reason farmers have abandoned the moldboard plow," he said.
>
> Horn added that farmers too often are criticized for causing environmental
> problems. "Here's a case where they're definitely part of the solution, and
> for that, they deserve a pat on the back," he said.
>
> ----------
> Scientific contact: Raymond R. Allmaras, ARS Soil and Water Management
> Research Unit, St. Paul, MN, phone (617) 625-1742, allmaras@soils.umn.edu.
> ----------
> This item is one of the news releases and story leads that ARS Information
> distributes on weekdays to fax and e-mail subscribers. You can also get the
> latest ARS news on the World Wide Web at
> http://www.ars.usda.gov/is/pr/thelatest.htm.
> * Feedback and questions to ARS News Service via e-mail: isnv@ars-grin.gov.
> * ARS Information Staff, 5601 Sunnyside Ave., Room 1-2251, Beltsville MD
> 20705-5128, (301) 504-1617, fax 504-1648.
>
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