1. USDA-ARS; Pasture Systems and Watershed Management Research Unit; University Park PA 16802
2. Dep. Crop and Soil Sciences; Oregon State Univ.; Corvallis OR 97331
3. Agricultural Analytical Services Lab.; Pennsylvania State Univ.; University Park PA 16802
4. Agricultural and Biological Engineering; Pennsylvania State Univ.; University Park PA 16802
5. School of Veterinary Medicine, Univ. of Pennsylvania; Kennett Square PA 19348
6. USDA-ARS; National Soil Tilth Lab.; Ames IA 50011
7. USDA-ARS; Northwest Irrigation and Soils Research Lab.; Kimberly ID 83341
8. Dep. of Crop and Soil Environmental Sciences; Virginia Polytechnic Univ.; Blacksburg VA 24061
9. USDA-ARS; Poultry Production and Product Safety Research Unit; Fayetteville AR 72701
10. Dep. Crop, Soil and Environmental Sciences; Univ. of Arkansas; Fayetteville AR 72701
11. Dep. Soil and Water Science; Univ. of Florida; Gulf Coast Research and Education Center; Wimauma FL 33598
12. Dep. Plant and Soil Sciences; Univ. of Delaware; Newark DE 19716
13. Dep. Biological and Agricultural Engineering; Univ. of Arkansas; Fayetteville AR 72701
14. Dep. Plant and Soil Sciences; Oklahoma State Univ.; Stillwater OK 74078
15. Environmental Health, Greenhouse and Processing Crops Research Center; Agriculture and Agri-Food Canada; Harrow ON Canada N0R 1G0