1. Department of Rural Economy, ABC Foundation Agricultural Research and Development, Castro, Parana State, Brazil;
2. Department of Soil Science and Agricultural Engineering, ABC Foundation Agricultural Research and Development, Castro, Parana State, Brazil;
3. Department of Computer Science, State University of Ponta Grossa, Ponta Grossa, Parana State, Brazil;
4. Department of Soils and Agricultural Engineering, Federal University of Paraná, Curitiba; Paraná State, Brazil