1. Professor, Department of Crop Science, College of Agriculture, Life and Environment Sciences, Chungbuk National University, Cheongju 28644, Korea
2. Post-Doctoral Fellow, Division of Soil and Fertilizer, National Institute of Agricultural Sciences, RDA, Wanju 55365, Korea
3. Chief Research Scientist, Division of Soil and Fertilizer, National Institute of Agricultural Sciences, RDA, Wanju 55365, Korea