1. Harrow Research and Development Centre, Agriculture & Agri-Food Canada; Harrow ON N0R 1G0 Canada
2. Texas A&M AgriLife Research, Blackland Research and Extension Center; Temple TX 76502 USA
3. Dep. of Bioresource Engineering; McGill Univ.; Sainte-Anne-de-Bellevue Quebec H9X 3V9 Canada
4. Dep. of Earth & Environmental Sciences; Univ. of Windsor; Windsor ON Canada