1. USDA‐ARS, Columbia Plateau Conservation Research Center P.O. Box. 370 Pendleton OR 97801
2. Dep. of Biological & Agricultural Engineering, Cooperative Extension Service Univ. of Arkansas Fayetteville AR 72701‐1201
3. Oregon State Univ. Columbia Basin Agricultural Research Center Pendleton OR 97801
4. Environmental Science Division Oak Ridge National Lab. P.O. Box 2008 Oak Ridge TN 37831‐6290