Matthew J. Rinella, ARS, Fort Keogh Livestock and Range Research Laboratory, 243 Fort Keogh Rd, Miles City, MT 59301, Bruce D. Maxwell, Land Resources and Environmental Sciences, Montana State University, P.O. Box 173120, Bozeman, MT 59717, and Roger L. Sheley, USDA-ARS, 67826-A Hwy 205, Burns, OR 97720.