1. a Coastal Plain Soil, Water, and Plant Research Center, USD A‐ARS , 2611 West Lucas Street, Florence , SC , 29501–1242
2. b Polish Academy of Sciences, Institute of Agrophysics , Doswiadczalna 4,P.O. Box 201, Lublin 27 , 20–290 , Poland
3. c USDA‐ARS , Soybean and Nitrogen Fixation Research , 312 7 Ligon Street, Raleigh , NC , 27695–7631