1. Department of Soil Science; Sokoine University of Agriculture; PO Box 3008 Chuo Kikuu Morogoro Tanzania
2. Department of Agricultural Engineering and Land Planning; Sokoine University of Agriculture; PO Box 3003 Chuo Kikuu Morogoro Tanzania
3. Department of Earth & Environmental Sciences; KU Leuven; Celestijnenlaan 200 E B-3001 Heverlee Belgium