1. a Department of Agronomy and USDA, ARS , University of Nebraska , Lincoln , NE , 68583
2. b USDA, ARS , Appalachian Soil and Water Conservation Research Laboratory , P.O. Box 867, Beckley , WV , 25802–0867
3. c CORPOICA—La Libertad , A.A. 2011, Villavicencio—Meta , Colombia , South America