1. Dep. of Geophysics, 397 Panama MallStanford Univ.StanfordCA94305‐2215
2. Dep. of Crop and Soil SciencesWashington State Univ.PullmanWA99164
3. Dep. of Land, Air and Water ResourcesUniv. of CaliforniaDavisCA95616
4. Dep. of AgronomyIowa State Univ. of Science and TechnologyAmesIA50011‐1010
5. Dep. of Plants, Soils and ClimateUtah State Univ.LoganUT84322‐4820
6. Dep. of Civil & Architectural EngineeringUniv. of WyomingLaramieWY82071
7. Dep. of Biological and Ecological EngineeringOregon State Univ.CorvallisOR97331‐3906
8. Dep. of Plant and Soil SciencesUniv. of KentuckyLexingtonKY40546‐0091