Gustavo M. Vasques¹, Sabine Grunwald², D. Brent Myers³, Nicholas B. Comerford⁴, James O. Sickman⁵ and Willie G. Harris², (1)National Center of Soil Research, Embrapa - Brazilian Agricultural Research Corporation, Rio de Janeiro, Brazil, (2)Soil and Water Science, University of Florida, Gainesville, FL, (3)Agricultural Research Service, United States Department of Agriculture, Columbia, MO, (4)North Florida Research and Education Center, University of Florida, Quincy, FL, (5)Environmental Sciences, University of California, Riverside, Riverside, CA