1. Agricultural and Biological Engineering Department, University of Illinois at Urbana-Champaign, University of Illinois, Urbana, IL 61801.
2. Corresponding author. Phone: 217-333-9510. Fax: 217-244-0323. E-mail: vsingh@uiuc.edu
3. Eastern Regional Research Center, ARS, USDA, Wyndmoor, PA. Mention of brand or firm names does not constitute an endorsement by University of Illinois or USDA above others of similar nature not mentioned.