1. USDA‐ARS‐PSI Crop Systems and Global Climate Change Lab. Bldg. 001, Room no. 342, BARC‐W, 10300 Baltimore Ave. Beltsville MD 20705‐2350
2. Texas A&M Univ. 17360 Coit Road Dallas TX 75252
3. USDA‐ARS Cropping Systems Research Lab. 302 West I‐20 Big Spring TX 79720
4. Univ. of Maryland Dep. of Natural Resources Sciences and Landscape Architecture Plant Science Bldg., Room 2130 College Park MD 20742