1. USDA-ARS-SPA; National Agric. Water Quality Laboratory; P.O. Box 1430 Durant OK 74702-1430
2. USDA-ARS-SPA; Conservation Production Res. Laboratory; P.O. Drawer 10 Bushland TX 79012
3. USDA-ARS-SPA, Southern Plains Range Res. Station; Woodward OK 73801
4. USDA-ARS-SPA; Southern Plains Watershed and Water Quality Laboratory; P.O. Box 400 Chickasha OK 73018