1. Department of Geology and Soil Science (WE13); Ghent University; Krijgslaan 281/S8 B-9000 Gent Belgium
2. Department of Soil Management; Ghent University; Coupure Links 653 B-9000 Ghent Belgium
3. Department of Earth and Environmental Sciences; KU Leuven University; Celestijnenlaan 200E B-3001 Heverlee Belgium
4. Department of Natural Resources Management; Jimma University College of Agriculture and Veterinary Medicine; PO Box 307 Jimma Ethiopia