1. North Central Agricultural
Research
Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Brookings, South Dakota 57006, United
States
2. Soil and Water Management
Unit,
Agricultural Research Service, U.S. Department of Agriculture, St. Paul, Minnesota 55108, United States
3. Department of Soil, Water, and Climate, University of Minnesota, St. Paul, Minnesota 55108,
United States