PT - JOURNAL ARTICLE AU - Gordon R. Dutt AU - Eugene A. Mielke AU - Wade H. Wolfe TI - The Use of Soils for the Delineation of Viticultural Zones in the Four Corners Region AID - 10.5344/ajev.1981.32.4.290 DP - 1981 Jan 01 TA - American Journal of Enology and Viticulture PG - 290--296 VI - 32 IP - 4 4099 - http://www.ajevonline.org/content/32/4/290.short 4100 - http://www.ajevonline.org/content/32/4/290.full SO - Am J Enol Vitic.1981 Jan 01; 32 AB - Delineation of viticultural zones has been useful in making varietal recommendations and predicting wine quality. The California base 50 growing-degree-day model fails to predict zones in the Four Corners Region which are comparable to California, either in adaptable varieties, sugar and acid or color of red varieties. A new model has been developed based on modern soil surveys and altitude. The soil parameter most useful in describing viticultural adaptability is the mean annual soil temperature at 50 cm. This parameter subdivides soils into hyperthermic, thermic and messic. Most wine grapes in California are produced on thermic soils, hence, this soil group has been subdivided. Altitude (inter-related to temperature) is the secondary parameter. Zones defined are HT (hypothermic), T1 (low-level thermic), Tm (mid-level thermic), Th (high-level thermic), and M (messic). This system while encompassing the G.D.D. concept, allows for wider climatic conditions to be considered.