LOCATION LOMITAS AZEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, hyperthermic Lithic Haplocambids
TYPICAL PEDON: Lomitas very stony loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 2 inches; brown (7.5YR 5/4) very stony loam, brown (7.5YR 4/4) moist; weak thin platy structure; slightly hard, friable, nonsticky and nonplastic; few very fine roots; common very fine vesicular and common medium tubular pores; 70 percent stones, cobble and gravel; slightly effervescent; moderately alkaline (pH 8.0); abrupt wavy boundary. (2 to 5 inches thick)
Bw--2 to 10 inches; light brown (7.5YR 6/4) extremely gravelly loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure; slightly hard, very friable, nonsticky and slightly plastic; few very fine roots; few fine tubular pores; 75 percent gravel and cobble; calcium carbonate coatings on undersides of gravel; strongly effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (8 to 12 inches thick)
Bk--10 to 13 inches; light brown (7.5YR 6/4) extremely gravelly loam, brown (7.5YR 4/4) moist; massive; soft, very friable, slightly sticky and slightly plastic; common fine roots; common fine interstitial pores; 80 percent gravel and cobble; continuous calcium carbonate coatings on all gravel and cobble; violently effervescent; moderately alkaline (pH 8.2); abrupt irregular boundary. (0 to 3 inches thick)
2R--13 inches; hard andesitic tuff; continuous calcium carbonate coatings on surfaces and in fractures; few fine roots in rock fractures.
TYPE LOCATION: Pima County, Arizona; Organ Pipe National Monument; 660 feet east and 550 feet north of the southwest corner of section 11, T.18 S., R.5 W. Latitude 31 degrees, 52 minutes, 4 seconds N., Longitude 112 degrees, 45 minutes, 31 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Soil moisture: Intermittently moist in some part of the soil moisture control section during July-September and December-February. Driest during May and June. Typic aridic soil moisture regime.
Rock fragments: Averages more than 35 percent in the control section
Depth to bedrock: 10 to 20 inches
A horizon
Hue: 7.5YR, 10YR
Value: 4, 5, 6 or 7 dry, 3, 4 or 5 moist
Chroma: 2, 3, 4 or 6 dry, 3, 4 or 6 moist
Organic matter: less than 1 percent
Reaction: slightly or moderately alkaline
Calcium Carbonate: noneffervescent to violently effervescent
B horizon
Hue: 5YR, 7.5YR, 10YR
Value: 4 through 7 dry, 4 or 5 moist
Chroma: 3, 4, 6 or 8 dry, 3 or 4 moist
Texture: sandy loam, fine sandy loam, very fine sandy loam, loam (8 to 15 percent clay)
Reaction: slightly or moderately alkaline
Calcium Carbonate: noneffervescent to violently effervescent; partial to continuous coats on gravel, stones and cobble in lower part
C horizon: Is absent in some pedons
Hue: 5YR, 7.5YR, 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 4 or 6, dry or moist
Texture: sandy loam, fine sandy loam, loam (8 to 15 percent clay)
Calcium Carbonate: Strongly or violently effervescent
COMPETING SERIES: These are the Angelpoint (CA) and Blackeagle (T)(CA) series. Angelpoint and Blackeagle soils are moist in some part of the soil moisture control section for less than 20 days cumulative between July and September.
GEOGRAPHIC SETTING: Lomitas soils are on hills and mountains and have slopes of 5 to 65 percent. They formed in alluvium and colluvium from andesite, rhyolite, tuff, volcanic breccia, basalt and to some extent metamorphic rocks. Elevation is 1,000 to 3,000 feet. Mean annual precipitation is 2 to 10 inches occurring as summer thunderstorms and gentle winter rain. Mean annual air temperature is 69 to 78 degrees F. Frost-free period is about 240 to 350 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Contine, Ebon, Gunsight, Momoli and Pinamt series. Contine, Ebon and Pinamt soils are very deep and have argillic horizons. Gunsight soils are very deep and have calcic horizons. Momoli soils are very deep.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; medium to rapid runoff; moderate permeability.
USE AND VEGETATION: Used for livestock grazing. The vegetation is creosotebush, brittlebush, triangle, bursage, paloverde, ocotillo, saguaro, organ pipe cactus and cholla.
DISTRIBUTION AND EXTENT: South Central and Southwestern Arizona. MLRA is 40. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Pima County (Organ Pipe Cactus National Monument Survey Area), Arizona; 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 2 inches (A horizon)
Cambic horizon - the zone from 2 to 10 inches (Bw horizon)
Lithic contact - the boundary at 13 inches (R horizon)
Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Tenth Edition, 2006.
Revised for the correlation of AZ661, 2/2009, WWJ
ADDITIONAL DATA: NSSL Sample S78AZ-013-12