1. USDA‐ARS Pasture Systems and Watershed Management Research Unit University Park PA 16802 USA
2. USDA‐ARS Soil and Water Management Research Unit St Paul MN 55108 USA
3. USDA‐ARS Jornada Experimental Range Las Cruces NM 88003 USA
4. Environmental Working Group Minneapolis MN 55401 USA
5. USDA‐ARS Northwestern Irrigation and Soils Research Unit Kimberly ID 83341 USA
6. USDA‐ARS Grassland Soil and Water Research Unit Temple TX 76502 USA
7. Ag Science Center at Clovis New Mexico State Univ. Clovis NM 88101 USA
8. Jornada Experimental Range New Mexico State Univ. Las Cruces NM 88003 USA
9. USDA‐ARS Soil Management and Sugar Beet Research Unit Fort Collins CO 80526 USA