[1] Cornell Univ, Dept Crop & Soil Sci, Ithaca, NY 14853 USA
[2] Univ Laval, Dept Sols & Genie Agroalimentaire, Quebec City, PQ G1K 7P4, Canada
[3] Dominican Univ, Dept Biol, River Forest, IL 60306 USA
[4] USDA ARS, Pasture Syst & Watershed Management Res Unit, University Pk, PA 16802 USA