1. USDA-ARS; Ft. Collins CO
2. Crop and Soil Sciences; Michigan State Univ.; East Lansing MI
3. Lab. of Tree Ring Research; Univ. of Arizona; Tucson AZ
4. USDA-ARS; Mandan ND
5. Panhandle Research and Extension Center; Univ. of Nebraska; Scottsbluff NE
6. Peterson, Soil and Crop Sciences; Colorado State Univ.; Fort Collins CO