Carl Rosen is a Professor and Extension Soil Scientist and former Department Head in the Department of Soil, Water, & Climate at the University of Minnesota. He received his MS degree in Horticulture from Penn State University and a Ph.D. degree in Soil Science from UC Davis. His research and extension programs in Minnesota have focused on optimizing nutrient management for a variety of crops with particular emphasis on irrigated cropping systems. Efforts in recent years have also focused on water quality issues related to fertilizer use and use of municipal and industrial by-products as amendments for agricultural soils. He has authored or coauthored numerous publications and extension bulletins on the subjects of nutrient management, soil fertility, soil health, plant nutrition, and beneficial use of by-products for crop production.