1. Crop, Soil, and Environmental Sciences Dep. Univ. of Arkansas 1366 W. Altheimer Dr Fayetteville AR 72704 USA
2. Univ. of Arkansas Systems Division of Agriculture Lonoke Extension Center, 2001 Hwy. 70 E Lonoke AR 72086 USA
3. Agricultural Statistics Laboratory Univ. of Arkansas Fayetteville AR 72701 USA