1. Professor, Univ. of Idaho, 3793 N. 3600 E., Kimberly, ID 83341 (corresponding author).
2. Professor, Institute of Agronomy, Technical Univ. of Lisbon, Lisbon, Portugal.
3. Country Representative, Madagascar, Africa FAO; formerly, Chief Officer, Rome, Italy.
4. Professor, Katholic Univ., Leuven, Belgium.
5. Research Soil Scientist, USDA-ARS, Kimberly, ID 83341. E-mail: wright@nwisrl.ars.usda.gov