1. Harrow Research and Development Centre, Agriculture and Agri-Food Canada; Harrow ON Canada N0R 1G0
2. Carbon Management and Sequestration Center; The Ohio State Univ.; Columbus OH 43210
3. Dep. of Environmental Sciences; Southern Illinois Univ.; Edwardsville IL 62026-1099
4. Crop, Soil and Environmental Sciences; Univ. of Arkansas; Fayetteville AR 72701
5. Dep. of Plant and Soil Sciences; Univ. of Delaware; Newark DE 19716
6. Grassland, Soil and Water Research Lab., USDA-ARS; Temple TX 76502-6712
7. Dep. of Earth and Environmental Sciences; Univ. of Waterloo; Waterloo ON Canada N2L 3G1