LOCATION TIDWELL AZEstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, calcareous, thermic Lithic Torriorthents
TYPICAL PEDON: Tidwell sandy loam - cultivated (colors are for dry soil unless otherwise noted).
Ap--0 to 10 inches; light brownish gray (10YR 6/2) sandy loam, brown (10YR 4/3) moist; massive; slightly hard, very friable, nonsticky and nonplastic; common fine and few medium roots; few very fine tubular and interstitial pores; few fine sandstone fragments; strongly effervescent; moderately alkaline (pH 8.4); abrupt smooth boundary (4 to 12 inches thick).
C--10 to 16 inches; brown (10YR 5/3) sandy loam, brown (10YR 4/3) moist; massive; hard, very friable, slightly sticky and slightly plastic; few fine and medium roots; common very fine and few fine tubular pores; common fine and medium sandstone fragments; strongly effervescent; moderately alkaline (pH 8.2); gradual wavy boundary (3 to 8 inches thick).
R--16 inches; light gray (10YR 7/1) interbedded calcareous sandstone and pinkish gray (7.5YR 7/2) calcareous shale, pale brown (10YR 6/3) and brown (7.5YR 5/2) moist; extremely hard (sandstone) and very hard (shale); matted roots on the upper surface.
TYPE LOCATION: Graham County, Arizona; 700 feet north and 250 feet west of the E 1/4 corner of Sec. 7, T. 8 S., R. 26 E.
RANGE IN CHARACTERISTICS:
Soil moisture: Intermittently moist in some part of the soil moisture control section during December - January and June - September. Driest during May and June. Typic aridic soil moisture regime.
Soil Temperature: 62 to 66 degrees F.
Depth to bedrock: 7 to 20 inches
Rock fragments: ranges from 5 to 50 percent; averages less than 35
Reaction: slightly alkaline or moderately alkaline
Organic matter: less than 1 percent in the surface
A horizon
Hue: 7.5YR, 10YR
Value: 5 through 7 dry, 3 through 6 moist
Chroma: 2 or 3, dry or moist
C horizon
Hue: 7.5YR, 10YR
Value: 5 through 7 dry, 3 through 6 moist
Chroma: 2 through 4, dry or moist
Texture: sandy loam, loam (averages less than 18 percent clay)
Calcium carbonate: accumulations occur above and on the bedrock in some pedons
COMPETING SERIES: These are the Delgado (CA), Langwell (CA), Ripsey (AZ), Splanod (AZ), and Trigger (CA) series. Ripsey soils are moist in the soil moisture control section for longer periods due to a higher rainfall component. Splanod soils average more than 18 percent clay. Delgado, Langwell, and Trigger soils are in the Mohave Desert (MLRA 30), receive mostly winter precipitation, and are usually dry from April through November. Trigger soils have a paralithic contact above the lithic contact and should be classified as shallow Typic Torriorthents.
GEOGRAPHIC SETTING: Tidwell soils are on plateaus and mesas. Slopes range from 0 to 40 percent. The soils formed on interbedded calcareous sandstone, limestone and shale of lacustrine origin that is high in quartz and feldspars. Tidwell soils are at elevations of 2,600 to 3,400. Mean annual precipitation is 4 to 10 inches. The mean annual air temperature is 60 to 64 degrees F. The frost-free period is about 195 to 255 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Anthony, Comoro, Gila, and Glendale soils. These soils are very deep.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderate permeability.
USE AND VEGETATION: Small areas are cultivated. Most areas are used for very limited livestock grazing. Vegetation is mainly saltbush, creosote, mesquite and snakeweed.
DISTRIBUTION AND EXTENT: Southern Arizona. This soil occurs in LRR-D, MLRA 41. Tidwell soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Graham County (Safford Survey Area), Arizona, 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 10 inches (Ap horizon)
Entisol feature - the absence of diagnostic subsurface horizons
Lithic contact - the boundary at 16 inches (R horizon)
Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Tenth Edition, 2006.
Updated competing series section 3/18/08, CEM