1. Soil and Crop Sci. Dep.; Colorado State Univ.; Ft. Collins CO 80523
2. Southwest Kansas Exp. Stn.; Kansas State Univ.; Tribune KS 67879
3. USDA-ARS Northern Plains Res. Cent.; Mandan ND 58554
4. USDA-ARS Conservation and Production Res. Lab; Bushland TX 79012