1. Department of Agroecology; Aarhus University, Blichers Allé 20; 8830 Tjele Denmark
2. Department of Soil, Water, and Environmental Science; The University of Arizona, 1177 E. 4th Street; Tucson Arizona 85721 USA
3. Department of Civil Engineering; Aalborg University, Sofiendalsvej 11; 9200 Aalborg Denmark