F. Jack Hills is Extension Agronomist, Department of Agronomy and Range Science, University of California, Davis; Stanley S. Johnson is Agricultural Economist, College of Agriculture, University of Hawaii, Hilo (formerly with the U.S. Department of Agriculture at U.C., Davis]; Shu Geng is Associate Professor and Biostatistician Department of Agronomy and Range Science, U.C., Davis. Akbar Abshahi is former Graduate Student Department of Agronomy and Range Science, U.C., Davis. Gary R. Peterson is Extension Staff Research Associate, Department of Agronomy and Range Science, U.C., Davis.