1. a Laboratoire Agronomie et Environnement , I.N.R.A.‐E.N.S.A.I.A. , 2, Avenue de la Forét de Haye, 54500 , Vanddonvre‐lés‐Nancy , France
2. b Department of Crop and Soil Environmental Sciences , Virginia Polytechnic Institute and State University , Blacksburg , VA , 24061–0404