1. Agriculture and Agri-Food Canada; Lethbridge Research Centre; 5403 1st Avenue South Lethbridge AB T1J 4B1 Canada
2. International Plant Nutrition Institute; 2301 Research Park Way, Suite 126 Brookings SD 57006
3. USDA-ARS; Natural Resource Conservation Center; 1420 Experiment Station Rd. Watkinsville GA 30677
4. Plant and Soil Science Dep.; 368 Ag Hall, Oklahoma State Univ. Stillwater OK 74078-6028
5. Joint Global Change Research Institute; Pacific Northwest National Lab.; Univ. of Maryland; 8400 Baltimore Ave., Suite 201 College Park MD 20740-2496
6. Dep. of Animal Science; Cornell Univ.; 323 Morrison Hall Ithaca NY 14853
7. Dep. of Soil Science; Univ. of Manitoba; Winnipeg MB R3T 2N2 Canada
8. Cary Institute of Ecosystem Studies; P.O. Box AB Millbrook NY 12545