LOCATION STEWART AZEstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, thermic, shallow Typic Haplodurids
TYPICAL PEDON: Stewart loam - rangeland (Colors are for dry soil unless otherwise noted.)
En1--0 to 2 inches; light gray (10YR 7/2) light loam, grayish brown (10YR 5/2) moist; moderate thin platy structure; slightly hard, very friable, nonsticky, nonplastic; many fine and medium roots; many fine and medium vesicular and few fine tubular pores; slightly effervescent; very strongly alkaline (pH 9.4); abrupt smooth boundary. (1 to 4 inches thick)
En2--2 to 6 inches; light gray (10YR 7/2) loam, brown (10YR 5/3) moist; massive; slightly hard, very friable, nonsticky, nonplastic; many fine and medium roots; common fine tubular pores; slightly effervescent; very strongly alkaline (pH 9.6); abrupt wavy boundary. (1 to 6 inches thick)
Bn--6 to 9 inches; brown (7.5YR 5/4) fine sandy loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure; hard, friable, slightly sticky, slightly plastic; many fine and medium roots; few fine tubular pores; few thin clay films in pores, few dark stains on faces of peds; slightly effervescent; very strongly alkaline (pH 9.6); abrupt smooth boundary. (2 to 10 inches thick)
2Cknsim--9 to 18 inches; light yellowish brown (10YR 6/4) indurated duripan, dark yellowish brown (10YR 4/4) moist; many large distinct dark gray (5YR 4/1) coatings, black (10YR 2/1) moist; few fine faint brownish yellow (10YR 6/6) veins or root channels, yellowish brown (10YR 5/6) moist; massive; extremely hard, very firm; common very fine and fine roots; many fine and very fine vesicular and tubular pores; slightly effervescent; few fine light gray (10YR 7/2) lime filaments; very strongly alkaline (pH 9.6); clear wavy boundary. (1 to 12 inches thick)
2Cnsim--18 to 22 inches; light gray (10YR 7/2) indurated duripan, dark grayish brown (10YR 4/2) moist; massive; very hard, very firm; many fine and very fine vesicular and tubular pores; slightly effervescent; very strongly alkaline (pH 9.6); clear wavy boundary. (2 to 6 inches thick)
3Cnt--22 to 33 inches; light gray (10YR 7/2) fine sandy loam, dark grayish brown (10YR 4/2) moist; massive; hard, friable, slightly sticky, slightly plastic; common fine and very fine vesicular and tubular and few coarse tubular pores; few thin clay films in root channels; slightly effervescent; very strongly alkaline (pH 9.6); abrupt wavy boundary. (3 to 15 inches thick)
3Cn--33 to 37 inches; light gray (10YR 7/1), light gray (10YR 7/2) and light gray (2.5Y 7/2) stratified sand and loamy sand, grayish brown (10YR 5/2) and 2.5Y 5/2) moist; structureless; slightly hard, very friable, nonsticky, nonplastic; many very fine interstitial pores; very slightly effervescent; very strongly alkaline (pH 9.6); abrupt wavy boundary. (0 to 4 inches thick)
3Cng1--37 to 42 inches; pale yellow (5Y 7/3) and light gray (2.5Y 7/2) stratified loam, sandy loam and loamy sand, olive (5Y 4/3) and dark grayish brown (2.5Y 4/2) moist; massive; hard, firm and friable, nonsticky, nonplastic and slightly plastic; few fine tubular pores; slightly effervescent; very strongly alkaline (pH 9.6); abrupt wavy boundary. (2 to 8 inches thick)
3Cng2--42 to 51 inches; pale yellow (5Y 7/3) sand, olive (5Y 5/3) moist; single grained; loose, nonsticky, nonplastic; common fine interstitial pores; common fine gravel; slightly effervescent; very strongly alkaline (pH 9.6); abrupt wavy boundary. (2 to 10 inches thick)
3Ckng--51 to 60 inches; pale yellow (5Y 7/3) stratified loamy sand and sandy loam, olive (5Y 5/3) moist; massive; hard, friable, slightly sticky, slightly plastic; few pebbles; slightly to violently effervescent; common large pale yellow (2.5Y 8/2) soft lime masses, light gray (2.5Y 7/2) moist; very strongly alkaline (pH 9.6).
TYPE LOCATION: Cochise County, Arizona; 2 1/2 miles SW of Willcox on Arizona Highway 86; 2,500 feet E. and 850 feet N. of the southwest corner of sec. 11, T.14S., R.24E.
RANGE IN CHARACTERISTICS:
Thickness of the solum and depth to the duripan: 4 to 20 inches.
Exchangeable sodium: 15 to 25 percent.
The control section averages less than 18 percent clay.
Soil moisture: Intermittently moist in some part of the soil moisture control section during July-September and December-February. Driest during May and June. The epipedon is moist in some part less than 90 days (cumulative) when the soil temperature is above 41 degrees F. in 7 out of 10 years. Typic aridic moisture regime.
Average annual soil temperature: 59 degrees to 68 degrees F.
In some pedons a thin A1 horizon is present
hue of 10YR or 7.5YR
value of 5 or 6 dry and 3 or 4 moist
chroma of 2 or 3
E horizon
Hue: 10YR or 7.5YR
Value: 5 through 7 dry and 4 through 6 moist
Chroma: 1 through 3
Texture: sandy loam, loam, or silt loam
Reaction; strongly to very strongly alkaline.
Bn horizon
Hue: 7.5YR or 10YR
Value: 5 through 7 dry and 4 or 5 moist
Chroma: 2 through 4
Texture: fine sandy loam, sandy loam, loam, silt loam or light sandy clay loam. Texture: strongly alkaline to very strongly alkaline.
2Cnsim horizons
Hue: 7.5YR through 2.5Y
Value: 4 through 7 dry and 3 through 5 moist
Chroma: 2 through 4
Texture: the duripan, when crushed, is sandy loam, fine sandy loam, loam, silt loam or sandy clay loam.
The soil material below the duripan is highly stratified. Texture ranges from clay to gravelly sand, and thickness of layers is quite variable. There may be several thin cemented duripans within a 60-inch profile.
COMPETING SERIES: These are the Alko (NV), Muroc (CA), Nebona (CA), and Zalda (NV) series. All these soils are well drained. In addition, they are in the Mohave Desert (MLRA 30), and are moist in some part of the moisture control section for 10 to 20 days cumulative during the period July through October. Muroc and Zalda soils are shallow to a thin duripan over bedrock.
GEOGRAPHIC SETTING: The Stewart soils are at elevations of 3,800 to 4,300 feet on level to nearly level and gently sloping low terraces and alkali flats bordering large playas. Slopes are dominantly 0 to 1 percent and range from 0 to 5 percent. Microrelief may be uneven due to wind shifting of the surface soil. These soils formed in old lake and fan deposited alluvium from mixed sources, including rhyolite, andesite, quartzite and granite. The climate is warm semiarid continental. The mean annual temperature ranges from 58 degrees to 66 degrees F. The frost-free period ranges from 155 to 220 days. The annual precipitation ranges from 10 to 12 inches and occurs as thundershowers from July through September and as gentle fall and winter rains. May and June are usually dry.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cogswell, Comoro, Elfrida and Karro soils in addition to the competing Crot, Duncan, Frye and Gothard soils. Cogswell and Elfrida soils have mollic epipedons and distinct zones of calcium carbonate accumulation. Comoro soils have mollic epipedons. Karro soils have distinct zones of calcium carbonate accumulation at shallow depths. None of the above listed soils have duripans at shallow depths.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff and ponded in low areas; very slow permeability.
USE AND VEGETATION: Used almost exclusively as rangeland. Native vegetation is alkali sacaton, Inland saltgrass, some scattered mesquite, annual weeds and grasses, and up to 50 percent barren areas.
DISTRIBUTION AND EXTENT: Southeastern Arizona and possibly southwestern New Mexico adjacent to playas and intermittent streams. The series is moderately extensive. MLRA 41.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Sulphur Spring Valley Area, Arizona, 1941.
REMARKS: The Stewart series was formerly classified in the Solonchak great soil group.
Additional Data: NSSL data # S69AZ 003 006