LOCATION LUKE AZEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, mixed, superactive, hyperthermic Typic Argidurids
TYPICAL PEDON: Luke very gravelly sandy clay loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 1 inch; yellowish red (5YR 5/6) very gravelly sandy clay loam, yellowish red (5YR 4/6) moist; moderate thin platy structure; slightly hard, friable, sticky and plastic; many very fine roots; many very fine interstitial pores; 45 percent pebbles and 5 percent cobbles; noneffervescent; moderately alkaline (pH 8.0); abrupt smooth boundary. (1 to 3 inches thick)
Bt1--1 to 2 inches; yellowish red (5YR 5/6) very gravelly sandy clay, yellowish red (5YR 4/6) moist; moderate fine subangular blocky structure; slightly hard, friable, very sticky and very plastic; many very fine roots; common very fine tubular pores; 50 percent pebbles; few thin clay films on faces of peds and lining pores; noneffervescent; moderately alkaline (pH 8.0); abrupt smooth boundary.
Bt2--2 to 14 inches; red (2.5YR 5/6) very gravelly clay, dark red (2.5YR 3/6) moist; strong medium subangular blocky structure; hard, friable, very sticky and very plastic; many very fine roots; common very fine tubular pores; 40 percent pebbles; common thin clay films on faces of peds; noneffervescent; moderately alkaline (pH 8.0); clear wavy boundary.
Bt3--14 to 28 inches; red (2.5YR 5/6) extremely gravelly clay, red (2.5YR 4/6) moist; moderate medium subangular blocky structure; hard, friable, very sticky and very plastic; common very fine roots; few very fine tubular pores; 75 percent pebbles; few thin clay films on faces of peds; noneffervescent; moderately alkaline (pH 8.0); abrupt wavy boundary. (Combined thickness of the Bt horizons is 19 to 37 inches.)
2Bqm--28 to 34 inches; silica-cemented hardpan with laminar surface; slightly effervescent; moderately alkaline (pH 8.2); clear wavy boundary. (2 to 6 inches thick)
2Bqk--34 to 60 inches; pink (5YR 8/3) dry and pink (5YR 7/4) moist; weakly silica-lime cemented material that breaks down to extremely gravelly loamy sand texture; few very fine tubular pores; 70 percent pebbles; strongly effervescent; moderately alkaline (pH 8.2)
TYPE LOCATION: Maricopa County, Arizona; 2,100 feet north and 410 feet west of the southeast corner of section 27, T. 6 N., R. 2 W.
RANGE IN CHARACTERISTICS:
Soil moisture: intermittently moist in some part of the SMCS during July-September and December-February. Typic aridic moisture regime.
Rock fragments: 35 to 85 percent; dominantly pebbles, with a few cobbles in some pedons.
Depth to duripan: 20 to 40 inches.
A horizon
Hue: 7.5YR or 5YR
Value: 5 to 7 dry, 3 to 5 moist
Chroma: 3 to 6 dry or moist
Calcium carbonate: noneffervescent or slightly effervescent with disseminated lime
Reaction: slightly or moderately alkaline
B horizon
Hue: 5YR or 2.5YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 4 to 6 dry or moist
Texture: clay, sandy clay (40 to 55 percent clay)
Calcium carbonate: noneffervescent or slightly effervescent in the upper part; noneffervescent to violently effervescent in the lower part. Some pedons contain common accumulations and/or soft masses of lime in the B horizon.
Reaction: slightly or moderately alkaline.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Luke soils are on fan terraces and have slopes of 1 to 8 percent. They formed in alluvium derived from acid and basic igneous rocks. Elevations are 1,400 to 2,200 feet. The climate is hot, arid continental. Average annual precipitation is 7 to 10 inches, occurring as summer thunderstorms and gentle winter rains. Mean annual temperature is 70 to 74 degrees F. The frost-free period is about 250 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: In addition to the similar Beardsley, Contine and Ebon soils, these are the Cipriano, Gunsight and Suncity soils. Cipriano and Gunsight soils lack an argillic horizon. Suncity soils are loamy. Gunsight soils also lack a duripan.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; slow permeability.
USE AND VEGETATION: Used for grazing. The present vegetation is creosotebush, triangle bursage, saguaro, littleleaf paloverde, cholla, barrel cactus and Indian wheatgrass.
DISTRIBUTION AND EXTENT: South Central Arizona. The series is not extensive. MLRA 40.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Maricopa County, Arizona, 1982.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 1 inch (A horizon)
Argillic horizon - The zone from 1 to 28 inches (Bt horizons)
Duripan- The zone from 28 to 34 inches (2Bqm horizon)
Classified according to Keys to Soil Taxonomy Tenth Edition, 2006