An intensive 2-year study of mean annual soil temperatures (MAST) was conducted in an attempt to more accurately classify the soils of the Fort Hall Area, Idaho, Soil Survey into the new Soil Taxonomy. Temperature data was obtained from 21 sites partly from deep samplings (7 to 9 m) with an extension auger and partly from monthly readings taken at depths of 0.6, 0.9, 1.2, and 1.5 m.
Sites were selected under native vegetation to include a range in elevations (1,330 to 1,860 m), drainage, soil texture, and slope. Drainage classes ranged from excessively drained to very poorly drained; textures ranged from loamy coarse sand to silt loam with one site a peat; slopes were nearly level with one 11% south slope and a 20% north slope.
Soils having MAST less than 8C (47F) occurred only above 1,830 m (6,000 ft) elevation or only under very poorly drained conditions. MAST was generally 2.5 to 3C (4.5 to 5.5F) warmer than the mean annual air temperature in the study area except where influenced by slope, texture, or drainage.
Mean summer soil temperature (MSST) of all well-drained soils was above 15C.