Geologist Jim Kilburn, now retired from the U.S. Geological Survey, collects soil from Kansas in 2008. Courtesy of USGS

It took an army of students and volunteers, thousands of bags, and travel to all of the lower 48 states, but the mission is, more or less, complete. “It” is a national-scale survey of soils from 5,000 places in the U.S., based on GPS coordinates.  The federal government’s initiative – aka the North American Soil Geochemical Landscapes Project – is the first-ever geochemical and mineralogical survey of soils. It is the brainchild of David Smith, a 38-year veteran of the U.S. Geological Survey, who started the project in 2001.

What’s the big deal ? Mapping of these soils, as well as the follow-on data, will be key to  future farming, forensics and other research. It may make it possible to modify how farming is conducted to address climate change. For forensic scientists, evidence such as mud-caked boots could be checked against the soil data to advance a criminal or civil case.

The careful sampling protocol involved taking three soil samples every 600 miles, based on the GPS coordinates, from the soil profile, starting at the surface and going no more than three feet in depth.

The survey provides a “ baseline for soil geochemistry and mineralogy against which future changes may be recognized and quantified.” The soils can be analyzed for a suite of 45 major and trace elements by methods that yield the total or near-total elemental content.

Virginia Tech, Cornell University and private research centers are already using the USGS soil survey for their research, including, for instance, to check for evidence of black carbon – a byproduct of forest fire—or study the effects of acid rain. “The opportunities for further research are almost limitless,” says Smith. Access the soil survey

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