Just a note of thanks to Chris Alenson for a lovely and lucid explanation of the use of rock dusts for mineral nutrition. Hats off to you - may I print out and use your message in my Crop Ecology course? Ann ACLARK@crop.uoguelph.ca Dr. E. Ann Clark Associate Professor Crop Science University of Guelph Guelph, ON N1G 2W1 Phone: 519-824-4120 Ext. 2508 FAX: 519 763-8933