1. Dep. Land Resources and Environmental Science Montana State Univ. 334 Leon Johnson Hall Bozeman MT 59715‐3120 USA
2. Dep. Agronomy and Horticulture Univ. of Nebraska – Lincoln 3257 Road 109 PHREC‐HPAL Sidney NE 69162‐3129 USA
3. Dep. Agronomy Univ. of Wisconsin – Madison 1575 Linden Drive Madison WI 53706 USA
4. Dep. Agronomy and Horticulture Univ. of Nebraska – Lincoln 76025 Rd 329 Grant NE 69140 USA
5. Dep. Agronomy and Horticulture Univ. of Nebraska – Lincoln 4502 Ave 1 Scottsbluff NE 69361‐4939 USA