LOCATION SAMINIEGO AZEstablished Series
TAXONOMIC CLASS: Clayey over loamy, mixed, superactive, hyperthermic Fluventic Haplocambids
TYPICAL PEDON: Saminiego silty clay loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 2 inches; brown (10YR 5/3) silty clay loam, dark brown (10YR 3/3) moist; moderate, medium subangular blocky structure; slightly hard, firm, moderately sticky and moderately plastic; common fine tubular pores; strongly effervescent; slightly alkaline (pH 7.8); abrupt smooth boundary. (1 to 4 inches thick)
Bw1--2 to 8 inches; brown (10YR 4/3) clay, very dark grayish brown (10YR 3/2) moist; strong moderate prismatic structure parting to strong moderate subangular blocky; moderately hard, very firm, moderately sticky and very plastic; common fine tubular pores; strongly effervescent; slightly alkaline (pH 7.6); gradual wavy boundary. (4 to 8 inches thick)
Bw2--8 to 21 inches; dark grayish brown (10YR 4/2) clay, very dark grayish brown (10YR 3/2) moist; strong moderate prismatic structure parting to strong moderate subangular blocky; very hard, extremely firm, moderately sticky and very plastic; common fine tubular pores; strongly effervescent; slightly alkaline (pH 7.6); clear wavy boundary. (9 to 16 inches thick)
Bk--21 to 30 inches; dark grayish brown (10YR 4/2) clay, very dark grayish brown (10YR 3/2) moist; strong fine subangular blocky structure; very hard, extremely firm, moderately sticky and very plastic; common fine tubular pores; common fine segregated calcium carbonate occurs in root channels; strongly effervescent; slightly alkaline (pH 7.6); abrupt smooth boundary. (6 to 11 inches thick)
2C--30 to 60 inches; brown (10YR 5/3) silty clay loam, dark brown (10YR 3/3) moist; massive; slightly hard, firm, moderately sticky and moderately plastic; continuous thin organic staining in desiccation cracks; common very fine tubular pores; strongly effervescent; slightly alkaline (pH 7.8)
TYPE LOCATION: Pinal County, Arizona; 2376 feet north and 132 feet west of southeast corner of sec. 7, T. 10 S., R. 9 E.
RANGE IN CHARACTERISTICS:
Soil moisture - Intermittently moist in some part of the soil moisture control section during July-September and December-February. Typic aridic moisture regime.
Rock fragments - Less than 5 percent gravel.
Depth to contrasting material - 20 to 40 inches but dominantly 24 to 30 inches.
Organic matter content - Greater than 1 percent throughout the control section.
A horizon -
Hue: 7.5YR or 10YR.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2, 3 or 4 dry, 2 or 3 moist.
Texture: Silty clay loam.
Carbonates: Less than 15 percent disseminated.
Reaction: Slightly or moderately alkaline.
B horizon -
Hue: 7.5YR or 10YR.
Value: 3 or 4 dry, 2 or 3 moist.
Chroma: 2, 3 or 4 dry, 1, 2 or 3 moist.
Texture: Clay, silty clay. (40 to 65 percent clay)
Carbonates: Less than 15 percent disseminated, common fine secondary accumulations in lower part.
Reaction: Slightly or moderately alkaline.
2C horizon -
Hue: 7.5YR or 10YR.
Value: 4 or 5 dry, 3 or 4 moist.
Chroma: 3 or 4 dry and moist.
Texture: Silty clay loam, silt loam. (10 to 30 percent clay averaging greater than 18 percent clay)
Reaction: Slightly or moderately alkaline.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Saminiego soils are on stream terraces of Holocene Age. Slopes are 0 to 1 percent. The soils formed in fine textured stream alluvium underlain by moderately fine silty-textured alluvium at depths of about 30 inches. The alluvium is derived form acid and basic igneous rocks; granite, schist, rhyolite, andesite, quartzite, limestone and basalt. Elevations are 1100 to 2200 feet. The climate is hot, arid continental. Average annual precipitation is 4 to 10 inches. Mean annual temperature is 67 to 75 degrees F. Frost-free period is about 240 to 350 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gadsden, Glenbar, Marana, Pimer and Sasco soils. Gadsden, Glenbar and Pimer soils are on floodplains and lack contrasting textures. Marana and Sasco soils lack contrasting textures.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained. Low or very low runoff. Low and moderately low saturated hydraulic conductivity.
USE AND VEGETATION: Used for limited grazing following seasonal rains. When irrigated, used for growing cultivated crops such as alfalfa, cotton and small grains. Native vegetation is mesquite, creosotebush, desertbroom, annual weeds and grasses.
DISTRIBUTION AND EXTENT: Southern Arizona. MLRA is 40. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Pinal County Area, Western Part, Arizona; 1982. Pronounced Sah-mah-nee-eh-go or Sam-min-yea-go.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Fluventic subgroup placement is based on the assumption that an irregular decrease in content of organic carbon occurs below 25 cm. NASIS data and the publication record that rare flooding conditions exist.
Cambic horizon - The zone from about 2 to 28 inches.
Organic matter - More than 1 percent throughout. Horizons not considered part of mollic epipedon because they do not meet the moisture requirements.
Contrasting textures - The difference in clay between upper and lower stories meets the minimum required - 25 percent.
The Keys to Soil Taxonomy Ninth Edition, 2003 removed the strongly contrasting particle-size class Clayey over fine-silty. The classification was changed to Clayey over loamy in 2006.
Classified according to Keys to Soil Taxonomy Ninth Edition, 2003