1. USDA-ARS; Wheat, Sorghum, and Forage Research Unit; 344 Keim Hall, Univ. of Nebraska Lincoln NE 68583
2. USDA-NRCS; P.O. Box 2890 Washington, DC 20013
3. Dep. Soil, Water, and Climate; 1991 Buford Circle, Univ. of Minnesota St. Paul MN 55108
4. USDA-ARS; Bushland TX 79012
5. USDA-ARS; National Soil Tilth Lab.; 2150 Pammel Drive Ames IA 50011
6. USDA-ARS; 215 Johnson Hall, Washington State Univ. Pullman WA 99164-6421