1. Dep. of Crop, Soil, and Environmental Sciences Univ. of Arkansas 115 Plant Sciences Building Fayetteville AR 72701 USA
2. Dep. of Geosciences Univ. of Arkansas 216 Ozark Hall Fayetteville AR 72701 USA
3. Dep. of Crop, Soil, and Environmental Sciences, Cooperative Extension Service Univ. of Arkansas System Division of Agriculture 2301 South University Ave. Little Rock AR 72204 USA
4. Dep. of Biological and Agricultural Engineering, Cooperative Extension Service Univ. of Arkansas System Division of Agriculture 2301 South University Ave. Little Rock AR 72204 USA
5. Arkansas Water Resources Center Univ. of Arkansas System Division of Agriculture Fayetteville AR 72704 USA