1. USDA-ARS; National Soil Erosion Research Lab.; Purdue University; West Lafayette IN 47907
2. USDA-NRCS, National Soil Quality Technology; 2901 E. Lee. St., Suite 2100 Greensboro NC 27401-4901
3. USDA-ARS; Northern Great Plains Research Lab.; Mandan ND 58554
4. USDA-ARS; Agroecosystem Management, Research Unit; University of Nebraska; Lincoln NE 68583
5. USDA-ARS; National Soil Tilth Lab.; Ames IA 50011