1. Dep. of Crop ScienceBox 8604, North Carolina State Univ.RaleighNC27695‐8604
2. Soil and Crop Sciences Dep.Texas A&M Univ.College StationTX77843‐2474
3. USDA‐ARS Pasture Systems and Watershed Management Res. Lab.Curtin RoadUniversity ParkPA16802‐3702