1. USDA‐ARS Natl. Soil Dynamics Lab. 411 S. Donahue Dr. Auburn AL 36832
2. USDA‐ARS J. Phil Campbell Sr.–Nat. Resour. Conserv. Cent. 1420 Experiment Stn. Rd. Watkinsville GA 30677
3. 202 Funchess Hall, Dep. of Agron. and Soils Auburn Univ. Auburn AL 36844
4. Tennessee Valley Res. and Exp. Stn. P.O. Box 159 Belle Mina AL 35615
5. Dep. of Agric. Eng. Auburn AL 36844