Luis Prochnow, Edificio Racz Center, International Plant Nutrition Institute Americas Group, Piracicaba, BRAZIL, Eros A. Francisco, Soil Fertility and Plant Nutrition, Research Foundation MT, Rondonopolis, Brazil, Aildson P. Duarte, IAC, Campinas, Brazil, Valter Casarin, International Plant Nutrition Institute, Piracicaba, Brazil, Adriel F. Fonseca, Agronomy, UEPG, Ponta Grossa, Brazil and Gabriel Barth, Research Foundation ABC, Ponta Grossa, Brazil