About the CR1 Soil:
CR1 soil is not a well-defined medium, yet not all soil is suitable for culturing a broad range of algae. Soil used for CR1 originates in the floodplain of the upper Rio de Flag, Flagstaff, Coconino Co., AZ. It is relatively low in organic content, pH circumneutral and is finely particulate in nature, consisting primarily of volcanic ash and weathered cinders and apparently contains a sufficient array of required trace elements and macronutrients.
Czarnecki, D. B. 1994. The freshwater diatom culture collection at Loras College, Dubuque, IA. In J. P. Kociolek [ed.], Proc. XI International Diatom Symposium, San Francisco. Memoirs Calif. Acad. Sci., No. 17, pp. 157-175. -----. 1988. The non-diatom algal culture collection at Loras College, Dubuque, IA. Cryptogamie Algologie, 9(3):203-209. Czarnecki, D. B. & M. J. Ross. 1988. The Itasca State Park Algal Culture Collection at Loras College. J. Minnesota Acad. Sci., 53(2):27-32. Czarnecki, D. B. 1987. The freshwater diatom culture collection at Loras College. Notulae Naturae Phil. Acad. Nat. Sci., No. 465, pp. 1-16. Nichols, H. W. 1973. I. Growth media freshwater. In J. R. Stein [ed.] Handbook of Phycological Methods I. Culture Methods & Growth Measurements. University Press, Cambridge, pp. 7-24. Pringsheim, E. G. 1946. Pure Cultures of Algae. University Press, Cambridge. 119 pp.
Preparation of the CR1 Soil:
The CR1 soil is treated in batches by placing in a heat-resistant pan lined with aluminum foil. Fill the soil to a so depth of ¼-inch and bake at 150 °C for 2 hours. After it cools, cover the pan with aluminum foil and store in darkness at room temperature. Avoid excessive moisture during storage.