1. Soil Science Department, Luiz de Queiroz College of Agriculture (ESALQ), University of São Paulo (USP), Piracicaba, Brazil
2. Laboratory of Nuclear Instrumentation (LIN), Center for Nuclear Energy in Agriculture (CENA), University of São Paulo (USP), Piracicaba, Brazil
3. Stable Isotopes Laboratory, Center for Nuclear Energy in Agriculture (CENA), University of Sao Paulo (USP), Piracicaba, Brazil