1. American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America; 900 Second Street, NE, Suite 205 Washington, DC 20002
2. Dep. of Soil Science; North Carolina State Univ.; Box 7619 Raleigh NC 27695-7619
3. USDA-ARS; Grazinglands Research Lab.; 7202 W. Cheyenne Street El Reno OK 73036