1. Res. Assoc., Yuma Agric. Ctr., Univ. of Arizona, Yuma, AZ 85364-9623.
2. Soil and Water Sci. and Dir., Yuma Agric. Center, Univ. of Arizona, Yuma, AZ.
3. Assoc. Prof. and Water Resour. Extension Spec., Dept. of Agric. and Biosys. Engrg. and Yuma Agric. Ctr., Univ. of Arizona, Yuma, AZ.