LOCATION PRIDHAM AZEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, thermic Typic Natraquolls
TYPICAL PEDON: Pridham loam - cropland. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 5 inches; gray (10YR 5/1) loam, very dark gray (10YR 3/1) moist; weak very fine and fine granular structure; slightly hard, friable, slightly sticky, slightly plastic; common very fine, fine and medium roots; many fine vesicular pores; noneffervescent; moderately alkaline (pH 8.2); abrupt smooth boundary. (1 to 6 inches thick)
Btnz1--5 to 11 inches; grayish brown (10YR 5/2) clay, very dark grayish brown (10YR 3/2) moist; weak medium prismatic parting to moderate medium subangular and angular blocky structure; very hard, friable, sticky, plastic; common very fine, fine and medium roots; few fine tubular pores; common thin clay films on faces of peds; slightly effervescent; strongly alkaline (pH 9.0); clear smooth boundary. (3 to 10 inches thick)
Btnz2--11 to 18 inches; grayish brown (10YR 5/2) clay, very dark grayish brown (10YR 3/2) moist; few fine faint light yellowish brown (10YR 6/4) mottles, dark yellowish brown (10YR 4/4) moist; moderate fine subangular blocky structure; very hard, firm, sticky, plastic; common very fine, fine and medium roots; few fine tubular pores; common thin clay films on faces of peds; strongly effervescent; few fine light gray (10YR 7/2) soft lime masses; strongly alkaline (pH 9.0); diffuse smooth boundary. (4 to 12 inches thick)
Btnz3--18 to 25 inches; light brownish gray (10YR 6/2) clay, dark grayish brown (10YR 4/2) moist; weak fine subangular blocky structure; hard, friable, sticky, plastic; common very fine, fine and medium roots; common thin clay films on faces of peds; strongly effervescent; common fine light gray (2.5Y 7/2) soft lime masses grayish brown (2.5Y 5/2) moist; strongly alkaline (pH 9.0 clear wavy boundary. (3 to 12 inches thick)
Cknzg--25 to 37 inches; mottled pale yellow (5Y 7/3), grayish brown (2.5Y 5/2), light brownish gray (2.5Y 6/2) and light brownish gray (10YR 6/2) and brown (7.5YR 5/4) clay loam, pale olive (5Y 6/3), very dark grayish brown (2.5Y 3/2), grayish brown (2.5Y 5/2) and grayish brown (10YR 5/2), and brown (7.5YR 4/4) moist; massive; hard, very friable, sticky, plastic; common very fine, fine and medium roots; violently effervescent; 10 percent by volume of very pale brown (10YR 8/2) soft lime masses; strongly alkaline (pH 9.0); clear wavy boundary. (8 to 34 inches thick)
Btknzb--37 to 54 inches; mottled brown (7.5YR 5/4) and light gray (2.5Y 7/2) clay loam, brown (7.5YR 4/4) and grayish brown (2.5Y 5/2) moist; moderate fine subangular blocky structure; hard, friable, sticky, plastic; few fine very dark gray (N 3/ ) concretions and common stains on faces of peds; black (N 2/ ) moist; violently effervescent; 10 percent by volume very pale brown (10YR 8/2) soft lime masses; strongly alkaline (pH 9.0).
TYPE LOCATION: Cochise County, Arizona; 200 feet E. and 2,600 feet S. of NW corner sec. 16, T.17S.,
RANGE IN CHARACTERISTICS:
Soil moisture:
Solum thickness and depth to the Ckzg horizon: ranges from 11 to 40 inches, but are usually 20 to 30 inches
Average annual soil temperature: 59 degrees to 65 degrees F.
Soil moisture: The soils are usually moist but are seasonally dry. The months of May and June are usually dry. Ustic aridic moisture regime based on precipitation. Aquic conditions exist for some time in normal years.
Ap horizon
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 1 or 2
reaction: neutral to strongly alkaline
B horizon
Hue: 5Y through 10YR, dominantly 10YR or 2.5Y
Value: 4 through 6 dry, 2 through 4 moist
Chroma: 1 through 3
Texture: clay loam or clay
Redoximorphic features: Gleyed horizons occur at depths of less than 20 inches
Reaction: moderately to very strongly alkaline
C horizon
Hue: 2.5Y or 5Y with some 10YR mottles
Texture: clay loam, clay, sandy clay loam, or loam
The buried Bt horizon is absent in some pedons.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Pridham soils are on level to nearly level low fans and valley plains at elevations of 4,000 to 5,000 feet. Slopes range from 0 to 2 percent but the micro-relief may be uneven. These soils formed in old alluvium from mixed sources, including rhyolite, andesite, quartzite, granite and limestone. The climate is warm semiarid continental. The mean annual temperature ranges from 58 degrees to 63 degrees F. The frost-free period ranges from 155 to 220 days. The annual precipitation ranges from 12 to 14 inches and occurs as thundershowers from July through September and as gentle fall and winter rains. The months of May and June are usually dry.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Cogswell and Guest soils and the Comoro, Forrest, Grabe, Pima and Tubac soils. Comoro and Grabe soils are moderately coarse-textured in the control section and lack an argillic horizon. Forrest and Tubac soils are both well drained, have hue of 7.5YR or redder, and lack an accumulation of salts more soluble than calcium sulfate. Pima soils are moderately fine-textured and lack an argillic horizon.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; slow permeability.
USE AND VEGETATION: Used for range and limited irrigated cultivated crops. Native vegetation is alkali sacaton, blue grama, tobosa grass and annual weeds and grasses. In the wetter areas, cattails, sedges and water cress occur and in the drier areas scattered mesquite grows.
DISTRIBUTION AND EXTENT: Southeastern Arizona. The series is of small extent. MLRA 41.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Willcox Area, Arizona, 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from 0 to 18 inches (Ap, Btnz1, Btnz2 horizons)
Natric horizon - the zone from 5 to 25 inches (Btnz horizons)
Aquic conditions - Aquic conditions exist for some time in normal years
These soils were formerly classified as Low Humic Gley soils.