He decided to bring soil samples to the laboratory and photograph them under controlled conditions.
For advice on photo equipment, O'Donnell sought out David Rees, chair of photojournalism at MU. O'Donnell procured a Nikon D80 camera, a 60mm f/2.8 macro lens and a pair of lens-mounted flashes to provide uniform, consistent lighting. His equipment purchases were funded in part by a scholarship named in honor of the late C.E. Marshall, an MU soil scientist and, as it turned out, the father-in-law of David Rees.
O'Donnell calibrated the software by photographing a brand-new set of Munsell color charts.
"I didn't know if this was going to work," O'Donnell recalled. The goal was to precisely quantify a soil sample's dominant colors in terms of hue, chroma (saturation) and value (lightness or darkness), as well as the abundance and distribution of those colors.
"It turns out that it works really well," he said. "The color identification was approximately 99 percent accurate for all the colors in the book."
Not only does the technique provide a more reliable way to identify hydric soils, it opens an avenue for collaboration with other disciplines by producing data about soil in a standardized, quantitative form, he said.
"Once you get here it opens up a door to new ways of looking at soils that haven't been looked at in the past," he said.
"It is a pretty ingenious amalgamation of techniques and ideas that provides soil scientists with a new tool for the 21st century," said Keith Goyne, an MU soil scientist.
O'Donnell describes his project in a paper that appeared recently in "Geoderma," considered a top-tier journal by soil scientists. O'Donnell's co-authors on the paper were Goyne, Stephen Anderson and Randall Miles of MU, and Claire Baffaut and Kenneth Sudduth of
|Contact: Curt Wohleber|
University of Missouri-Columbia