1. USDA‐ARS National Lab. for Agriculture and the Environment 1015 N. Univ. Boulevard Ames IA 50011‐3611 USA
2. USDA‐ARS, Cropping Systems and Water Quality Research Unit, 269 Agricultural Engineering Bldg. Univ. of Missouri Columbia MO 65211 USA
3. Dep. of Statistics Univ. of Missouri 134 Middlebush Hall Columbia MO 65211 USA
4. USDA‐ARS (retired) DLKarlen Consulting 487 Ashland Ave. St. Paul MN 55102 USA
5. Cornell Univ. School of Integrative Plant Science 233 Emerson Hall Ithaca NY 14853 USA
6. USDA‐NRCS National Soil Survey Center 100 Centennial Mall North, Room 152 Lincoln NE 68508 USA