1. USDA‐ARS, Plant Sciences 115University of ArkansasFayettevilleAR72701
2. Agronomy Department, Plant Sciences 115University of ArkansasFayettevilleAR
3. Dep. Agric. Eng., 128 Agric. Eng. BldgUniversity of KentuckyLexingtonKY40546‐0276
4. Agronomy and Soils Department, Funchess HallAuburn UniversityAlburnAL36849‐5412