1. a Animal Manure and By-Products Laboratory , USDA-ARS, Building 007, Room 015, 10300 Baltimore Avenue, BARC-West, Beltsville , MD , 20705 , U.S.A.
2. b Department of Natural Resources and Landscape Architecture, H.J. Patterson Hall , University of Maryland , College Park , MD , 20742 , U.S.A.