1. Department of Soil Science and Natural Resources Santa Catarina State University Lages SC Brazil
2. Department of Crop and Soil Sciences North Carolina State University Raleigh NC 27695 USA
3. Brazilian Agricultural Research Corporation (EMBRAPA) Brasília DF 70770‐901 Brazil
4. Department of Agriculture, Biodiversity and Forest. Curitibanos Federal University of Santa Catarina, Curitibanos SC Brazil
5. National Council for Scientific and Technological Development Lages SC 88520‐000 Brazil