1. Dep. of Civil Eng.; Univ. of Mississippi; 208 Carrier Hall, P.O. Box 1848, University Mississippi MS 38677-1848
2. USDA-ARS; National Soil Tilth Lab.; 2150 Pammel Dr., Ames IA 50011-4420
3. Bayer CropScience Res. Park; 17745 S. Metcalf Ave. Stilwell KS 66085
4. USDA-ARS; 2150 Centre Ave., Building D, Suite 200 Ft. Collins CO 80526