COLUMBIA, Mo. A University of Missouri doctoral student has developed a technique that uses digital imaging of soil samples to take some of the guesswork out of wetland identification.
Identifying wetlands isn't always easy. The U.S. Army Corps of Engineers' manual on wetlands identification is 143 pages long. Land that is wet isn't necessarily a wetland, and some wetlands aren't always wet. One important tool is looking at the soil for colors and patterns characteristic of frequent and prolonged saturation, said Kevin O'Donnell, a doctoral student in soil science at MU.
Chronic saturation changes a soil's structure and chemical composition and affects the types of microorganisms it harbors. These changes determine the colors and other visible features of soil. Soil scientists use those features to identify what they call "hydric soils."
A trusty companion of soil scientists in the field is a small loose-leaf binder holding a set of "Munsell Soil Color Charts," which contains 238 color chips and other visual aides for classifying soils.
There's a small hole adjacent to each chip that lets you compare the color chip and soil sample side-by-side.
"There's a lot of room for error," O'Donnell said. Cloud cover, time of day and many other factors can affect perception of a soil's appearance. Experienced soil scientists learn to take this into account, but even seasoned pros might come to different conclusions about a given sample.
"You're dealing with jurisdictional identification of wetlands," he said. "Imagine you're a landowner and a soil scientist comes out and says you have a hydric soil."
Wetlands are protected under the federal law, so landowners can end up facing restrictions on developing or farming their land based on a subjective assessment of the soil. "Will that hold up in court? I saw some major issues there."
In an earlier project, O'Donnell used software to analyze aerial ph
|Contact: Curt Wohleber|
University of Missouri-Columbia