1. Dep. of Crop, Soil, and Environ. Sciences; Univ. of Arkansas; 1366 W. Altheimer Dr. Fayetteville AR 72704
2. LSU Agricultural Center; Red River Research Station; 262 Research Station Dr. Bossier City LA 71112
3. Univ. of Arkansas; Marianna Soil Test Lab; Hwy. 1 South, P.O. Drawer 767 Marianna AR 72360