MOSCOW – A distinctive volcanic ash soil from northern and central Idaho will represent the state when the Smithsonian’s National Museum of Natural History launches its new exhibit “Dig It: The Secrets of Soil” this summer.

University of Idaho soil scientists say the Threebear soil with its cap of volcanic ash is a worthy representative. Only six states, Idaho, Montana, Washington, Oregon, California, Hawaii and Alaska, claim sizeable areas of volcanic soils.

First identified in southeastern Latah County along Threebear Creek, the distinctive soil is technically a yellowish brown silt loam. The volcanic ash cap is the source of the rich forests throughout northern and central Idaho.

The new Smithsonian exhibit, which opens July 19, will feature the Idaho soil along with those from all of the other states.

“The Threebear soil is among several soils in Idaho that have volcanic origins. The Rexburg soil of southeastern Idaho is another soil that is economically valuable because it grows Idaho’s famous potatoes,” said Paul McDaniel, a professor of soil science. However, Rexburg only contains small amounts of volcanic ash compared to Threebear.

The Natural Resources Conservation Service selected the Threebear soil as representative of Idaho soils in general and collaborated with the university to prepare a sample for display. Soil monoliths, mounted columns of soil preserved to show soil color and structure, will come from each state for the new Smithsonian exhibit.

The University of Idaho College of Agricultural and Life Sciences displays one of the most extensive collections of soil monoliths in the nation with more than 230. The collection is the legacy of Maynard A. Fosberg of Moscow, an emeritus professor of soil science who lives in Moscow.

More information about Fosberg and the collection is online at http://soils.ag.uidaho.edu/pedology/monolith/index.htm.

McDaniel maintains a popular website about the world’s soils at http://soils.ag.uidaho.edu/soilorders/

More information about the Smithsonian exhibit is at http://forces.si.edu/soils/index.html