1. Panhandle Research, Education and Extension Center, Dep. of Agronomy and Horticulture Univ. of Nebraska–Lincoln 4502 Avenue I Scottsbluff NE 69361 USA
2. USDA Agricultural Research Service, Central Great Plains Research Station Northern Plains Area, 40335 Rd. GG Akron CO 80720 USA
3. High Plains Ag Lab, Dep. of Agronomy and Horticulture Univ. of Nebraska–Lincoln 3257 Road 109 Sidney NE 69162 USA