1. Agricultural Engineering, Conservation and Production Research Laboratory, U.S. Dept. of Agriculture/Agricultural Research Service, P.O. Drawer 10, Bushland, TX 79012.
2. Agricultural Engineer, U.S., Water Conservation Lab., U.S. Dept. of Agriculture/Agricultural Research Service, 4331 East Broadway, Phoenix, AZ 85040.
3. Physical Scientist, U.S. Water Conservation Lab., U.S. Dept. of Agriculture/Agricultural Research Service, 4331 East Broadway, Phoenix, AZ 85040.
4. Associate Professor, Dept. of Agricultural and Biosystems Engineering, Univ. of Arizona, Tucson, AZ 85721.