1. Univ. of Nebraska South Central Res. and Ext. Center Clay Center NE 68933
2. Univ. of Nebraska‐Lincoln West Central Res. and Ext. Center North Platte NE 69101
3. Univ. of Nebraska Northeast Res. and Ext. Center–Haskell Ag Lab Concord NE 68728
4. Dep. of Agronomy Univ. of Nebraska Lincoln NE 68583