1. Center for Nuclear Energy in Agriculture; University of São Paulo; Avenida Centenário 303 Piracicaba 13400-970 São Paulo Brazil
2. IRD, CNRS, UPS, OMP; Géoscience Environnement Toulouse; 19 Av. Edouard Belin Toulouse F-31400 France
3. Department of Geography; Federal University of Mato Grosso do Sul; Rod. MS 134, Km 3 Nova Andradina 79750-000 Mato Grosso do Sul Brazil