1. Porous Media Research Lab, Department of Geology Kansas State University Manhattan KS 66506 USA
2. Department of Physics Wright State University Dayton OH 45435 USA
3. Department of Earth and Environmental Science Wright State University Dayton OH 45435 USA
4. Department of Agricultural and Food Sciences University of Bologna Bologna Italy
5. Department of Environmental Science The University of Arizona Tucson AZ 85721 USA
6. Department of Agroecology Faculty of Technical Sciences Technology Aarhus University Tjele Denmark