Tech Tuesday

Getting a Better Handle on Carbon?

Oak Ridge National Laboratory boosts ability to measure carbon dioxide activity from ag.

Just how much carbon dioxide does your farm emit. No matter your thoughts on that gas and the climate change work being done in Washington, DC, this is an issue agriculture will have to face. The folks at Oak Ridge National Laboratory say they've bumped up the "resolution" of carbon dioxide measurement using a new method, and that will offer better information for future regulations and measurement.

A research team used satellite remote sensing, computer models and high-resolution national inventory datasets to pinpoint ag-based carbon emissions. This is a hot topic because farmers also sequester carbon using some practices and getting an accurate handle across the whole farm will help regulators develop systems to measure just what you do on the farm. And it will guide regulators and lawmakers in ways to develope compensation systems under cap and trade type legislation (and while that idea has been set aside by Congress for now, it may return).

The method outlined by ORNL offers a link between ground-based estimates and atmospheric measurements for any given ag point in the nation. This is a solid step toward getting information that can be used for potential future carbon accounting approaches.

In the past, researchers looked at carbon emissions in two ways - at the project (or single farm) level and on a national level. The project-based approach was to determine carbon credits, while the national approach is for those United Nations reports.

Bringing the two kinds of data together is important as countries move forward with climate agreements. The ORNL method uses land cover data from NASA satellites to refine cropland carbon fluxes nationwide. USDA cropland data enables field-scale delineation of specific crops and allows for refined estimates on those carbon numbers.

This approach will provide a net exchange of carbon for any given ag point. The information about carbon flux based on crop, soil and management practices gives a measure of the total change in carbon emissions including fossil fuel emissions on the site. The effort would also provide estimates of net ecosystem carbon balance, which includes all carbon sources and sinks associated with crop production in a defined area.

This does mean that upstream emissions from fertilizer production are accounted for in the same place where the crop is produced. This method allows for an estimate of the total impact of changing cropland management on net CO2 emissions. Cropland management can have significant impacts here. For example reduced tillage from 1990 to 2004 resulted in a net emissions reduction of 8.8 million metric tons of CO2 from burning fossil fuels in the United States.

Further work is needed with the Oak Ridge models, but they do attempt to pull together data from a lot of locations and help make more precise conclusions that can be used down on the farm.

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