1. Institute for Soil Science and Agricultural ChemistryCentre for Agricultural Chemistry, Hungarian Academy of Sciences Budapest H‐1022 Hungary
2. Department of Crop Production and Soil Science, Georgikon FacultyUniversity of Pannonia Keszthely H‐8360 Hungary
3. European Commission Joint Research Centre Varese I‐21027 Italy
4. ISRIC ‐ World Soil Information Wageningen 6700 AJ The Netherlands