1. USDA-ARS; Northwest Irrigation and Soils Research Laboration, 3793N, 3600E; Kimberly ID 83341
2. Soil and Water Science Dep.; Univ. of Florida; 106 Newell Hall, P.O. Box 110510 Gainesville FL 32611
3. CSIRO Plant Industry; P.O. Box 1600 Canberra ACT 2601 Australia