1. ABC Foundation Dept. of Soil Fertility PR-151 km 288 84165–700 Castro, PR Brazil
2. Technical University of Munich Emil-Ramann-Straße 2 85354 Freising Germany
3. “Luiz de Queiroz” College of Agriculture–University of São Paulo Dept. of Soil Science 11 Padua Dias Ave. 13418-900 Piracicaba, SP Brazil
4. University of Missouri School of Natural Resources 302 ABNR Bldg 65211 Columbia, MO USA
5. Agronomic Institute of Campinas Av. Barão de Itapura, 1481–Botafogo 13075-630 Campinas–SP Brazil