1. Dep. of Natural Resources & Agriculture Agroscope; Reckenholzstrasse 191 CH-8046 Zürich Switzerland
2. Dep. of Soil & Environment; Swedish Univ. of Agricultural Sciences; Box 7014 SE-75007 Uppsala Sweden
3. Soil and Terrestrial Environmental Physics; Swiss Federal Institute of Technology; Universitätstrasse 16 CH-8092 Zürich Switzerland
4. School of Agricultural, Forest and Food Sciences (HAFL) Bern Univ. of Applied Sciences; Länggasse 85 CH-3052 Zollikofen Switzerland
5. Division of Hydrologic Sciences; Desert Research Institute; 755 E. Flamingo Road Las Vegas NV 89119