1. P.O. Box 3508, Southeast Research and Extension Center, Univ. of Arkansas Monticello AR 71656 USA
2. P.O. Box 48, Northeast Research and Extension Center, Univ. of Arkansas Keiser AR 72351 USA
3. 115 Plant Sciences Bldg., Dep. of Agronomy, Univ. of Arkansas Fayetteville AR 72701 USA
4. 403 Agricultural Engineering Bldg. 2, Dep. of Agric. Economics, Univ. of Kentucky Lexington KY 40546 USA
5. Dep. of Agricultural Economics and Agribusiness; Univ. of Arkansas; 221 Agriculture Bldg. Fayetteville AR 72701 USA
6. P.O. Box 351, Rice Research and Extension Center Stuttgart AR 72160 USA