1. Uni. of Rhode Island Kingston RI 02881 USA
2. Uni. of California Davis CA 95616 USA
3. USDA‐NRCS Sonora CA 95370 USA
4. Pennsylvania State Uni. University Park PA 16802 USA
5. Virginia Tech Uni. Blacksburg VA 24061 USA
6. USDA‐NRCS Washington DC 20250 USA
7. USDA‐NRCS Lincoln NE 68508 USA
8. University of Maryland College Park MD 20742 USA
9. Kansas State Uni. Manhattan KS 66506 USA
10. Auburn, Uni. Auburn AL 36849 USA