1. Department of Soil and Crop Sciences; Texas A&M University; College Station TX USA
2. CNPq, Conselho Nacional do Desenvolvimento Científico e Tecnológico; Brasília DF Brazil
3. Agricultural Research Service; US Department of Agriculture; Temple TX USA
4. BASF Corporation; Winnsboro LA USA
5. Texas AgriLife Research; David Wintermann Rice Research Center; Eagle Lake TX USA