1. USDA‐ARS, Beltsville Agricultural Research Center Sustainable Agricultural Research Laboratory 10300 Baltimore Ave. Beltsville MD MD 20705 USA
2. USDA‐ARS Conservation and Production Research Lab. 300 Simmons Rd. Bushland TX 79012 USA
3. USDA‐ARS Sustainable Water Management Research Unit 141 Experiment Station Rd. Stoneville MS 38766 USA
4. Dep. of Crop and Soil Science North Carolina State Univ. 1114 Williams Hall Raleigh NC 27695 USA