Before selling carbon credits, read this

May 18, 2007

Storing carbon in agricultural soils presents an immediate option to reduce atmospheric carbon dioxide and slow global warming. Farmers who adopt practices that store carbon in soil may be able to "sell" the stored carbon to buyers seeking to offset greenhouse gas emissions. Before farmers can sell carbon credits, however, they need to be able to verify that changing soil management has increased the soil organic carbon (SOC) in their fields.

Researchers at Montana and Colorado State Universities now have evidence that a soil model can be used to accurately estimate carbon levels in soil under certain climate and land conditions. By using this model, farmers and landowners will be able to verify soil carbon change for carbon trading. Scientists report their findings on the reliability of the Century soil model in the May-June 2007 issue of the Soil Science Society of America Journal.

Funding for this research was provided by the Upper Midwest Aerospace Consortium-Public Access Resource Center, the Consortium for Agricultural Soils Mitigation of Greenhouse Gases, and the Montana State University Agricultural Experiment Station.

"The Century model estimates soil organic carbon content and soil organic carbon change using soil texture, weather, and farm management information," said Ross Bricklemyer, lead author of the study.

Working together with farmers from Montana, researchers compared Century model estimates of soil carbon storage to field SOC measurements. Scientists measured carbon storage and soil texture in 10 paired fields under no-till and conventional-till management. They estimated the increase in carbon stored under no-tillage adoption as the difference between carbon levels in no-till and till fields. They then compared the soil carbon values predicted by the Century model to measured SOC and SOC rate of change.

The Century model accurately predicted SOC content and rate of carbon change, however, differences between measured soil texture data and state and county soil texture maps greatly influenced carbon storage estimates.

"The accuracy and scale of soil texture data highly influence the accuracy of Century model estimations of soil carbon," said Bricklemyer. "The model accurately estimated soil carbon content and the influence soil clay content had on the amount of carbon in the soil."

Although texture was important in determining SOC storage estimates, the effect of no-tillage management on the rate of carbon storage was not influenced by texture in this study. Some scientists have found that high clay content, or heavy soils, store carbon more rapidly under no-tillage management than soils with little clay content, others have found that clay content has no affect on carbon storage rates under no-tillage practice.

Bricklemyer says that because the effects of clay content on the rate of soil carbon under no-tillage change are not well understood by the research community, clay content information was not directly used by the Century model for carbon change calculations.

"This study also points out the importance of establishing benchmark monitoring sites, under actual farm conditions, where soil texture, soil carbon and other soil properties can be accurately measured and re-measured over time," said Bricklemyer. "Such a system, which currently doesn't exist in the U.S., would help us improve and validate estimates of carbon sequestration over time."

Source: American Society of Agronomy

Explore further: Saving Louisiana's coast

Related Stories

Saving Louisiana's coast

August 27, 2015

It was Day Nine after Katrina struck in 2005 when Sarah Mack's bosses at the Sewerage and Water Board of New Orleans called her back to work.

On warmer Earth, most of Arctic may remove, not add, methane

August 17, 2015

In addition to melting icecaps and imperiled wildlife, a significant concern among scientists is that higher Arctic temperatures brought about by climate change could result in the release of massive amounts of carbon locked ...

Tree domination of the world's savannas may slow down

August 12, 2015

Savannas are becoming increasingly woodier as trees gain the upper hand over grasses in these ecosystems, but this encroachment may proceed more slowly than previously thought, new University of Otago-led research suggests.

Recommended for you

Climate ups odds of 'grey swan' superstorms

August 31, 2015

Climate change will boost the odds up to 14-fold for extremely rare, hard-to-predict tropical cyclones for parts of Australia, the United States and Dubai by 2100, researchers said Monday.

Quantifying the impact of volcanic eruptions on climate

August 31, 2015

Large volcanic eruptions inject considerable amounts of sulphur in the stratosphere which, once converted into aerosols, block sun rays and tend to cool the surface of the Earth down for several years. An international team ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.