1. Department of Crop and Soil Science North Carolina State University Raleigh NC 27695 USA
2. Sustainable Agricultural Systems Laboratory USDA–ARS Beltsville MD 20705 USA
3. Feed and Environmental Water Laboratory The University of Georgia Cooperative Extension 2300 College Station Road Athens GA 30602 USA
4. Grain Legume Genetics and Physiology Research Unit USDA–ARS Pullman WA 99164 USA