LOCATION KARRO AZ+NMEstablished Series
TAXONOMIC CLASS: Fine-loamy, carbonatic, thermic Ustic Haplocalcids
TYPICAL PEDON: Karro loam, cultivated (colors are for dry soil unless otherwise noted).
Ap1--0 to 2 inches; light brownish gray (10YR 6/2) loam, dark yellowish brown (10YR 3/4) moist; weak medium and thick platy structure; slightly hard, friable, slightly sticky, slightly plastic; many fine and coarse roots; few very fine tubular pores; strongly effervescent; moderately alkaline (pH 8.4); abrupt smooth boundary (0 to 3 inches thick).
Ap2--2 to 11 inches; pale brown (10YR 6/3) loam, dark yellowish brown (10YR 3/4) moist; massive; slightly hard, friable, slightly sticky, slightly plastic; many fine, medium, and common coarse roots; many fine vesicular and few very fine tubular pores; strongly effervescent; moderately alkaline (pH 8.2); clear wavy boundary (8 to 10 inches thick).
Bk1--11 to 15 inches; pale brown (10YR 6/3) loam, brown (10YR 4/3) moist; massive; slightly hard, friable, slightly sticky, slightly plastic; many fine and medium roots; common fine and very fine tubular pores; violently effervescent; few fine nodules or fragments of lime; moderately alkaline (pH 8.2); clear smooth boundary (3 to 6 inches thick).
Bk2--15 to 30 inches; light gray (10YR 7/2) clay loam, pale brown (10YR 6/3) moist; common light brownish gray (10YR 6/2) coatings, brown (10YR 5/3) moist; moderate fine and medium subangular blocky structure; very hard, friable, sticky, plastic; common fine and medium roots; violently effervescent; many nodules and irregularly shaped soft fragments of lime; very strongly alkaline (pH 9.0); gradual wavy boundary (12 to 24 inches thick).
Bk3--30 to 45 inches; very pale brown (10YR 8/2) clay loam, very pale brown (10YR 8/2) moist; few light gray (10YR 7/2) coatings, light brownish gray (10YR 6/2) moist; moderate medium and fine angular and subangular blocky structure; hard, friable, sticky, plastic; few fine roots; many very fine tubular and irregular pores; violently effervescent; many irregularly shaped soft masses of lime; very strongly alkaline (pH 9.4); gradual wavy boundary (10 to 20 inches thick).
Bk4--45 to 60 inches; very pale brown (10YR 8/2) and light yellowish brown (10YR 6/4) clay loam, light gray (10YR 7/2) and yellowish brown (10YR 5/4) moist; massive; hard, friable, sticky, plastic; violently effervescent; many fine, medium, and coarse irregularly shaped masses and nodules of lime; about 50 percent calcium carbonate; strongly alkaline (pH 8.8).
TYPE LOCATION: Cochise County, Arizona; 150 feet west, 900 feet north of SE corner Section 23, T.15S., R.25E.
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. Ustic aridic soil moisture regime.
Soil temperature: 59 to 72 degrees F.
Depth to calcic horizon: 10 to 24 inches
Calcium carbonate equivalent: more than 40 percent
Ap horizon
Hue: 10YR, 7.5YR
Value: 5 through 7 dry, 3 or 4 moist
Chroma: 2 through 4, dry or moist
Organic matter content: 1 to 2 percent
Bk horizons
Value: 6 through 8 dry, 4 through 8 moist
Chroma: 2 through 4 dry or moist
Texture: loam, silt loam, clay loam
Clay content: 18 to 35 percent
In some pedons, the Bk2 and Bk3 horizons are weakly cemented.
COMPETING SERIES: These are the Armesa (NM), Cesario (TX), and Fizzleflat (TX) series. Armesa soils are inactive. Cesario soils are deep to shale of the Pen Clay Formation. Fizzleflat soils are moderately deep to shale of the Pen Clay Formation.
GEOGRAPHIC SETTING: The Karro soils formed in mixed fan alluvium on alluvial fans, valley plains, and lake margins at elevations of 3,600 to 4,800 feet. Slopes are dominantly less than 1 percent and range from 0 to 15 percent. The climate is arid or semiarid continental. The mean annual air temperature ranges from 58 degrees to 68 degrees F. The frost-free period ranges from 180 to 230 days. The mean annual precipitation ranges from 10 to 16 inches and falls mainly in thundershowers in July, August, and September and in gentle rains in December and January. May and June are usually dry.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Frye, Gothard, and McAllister soils. Frye, Gothard, and McAllister soils have argillic horizons.
DRAINAGE AND PERMEABILITY: Well-drained; slow to medium runoff; moderate to moderately slow permeability.
USE AND VEGETATION: Used for range and irrigated cropland. Native vegetation is mesquite, fluffgrass, tobosa, creosote, atriplex, blackbrush, and alkali sacaton.
DISTRIBUTION AND EXTENT: Southeastern Arizona and southwestern New Mexico. Karro soils are moderately extensive. MLRAs 41 and 42.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: San Simon Area, Cochise County, Arizona, 1921.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 11 inches (Ap1 and Ap2 horizons)
Calcic horizon - The zone from 15 to 29 inches (Bk2, Bk3, Bk4 horizons)
Classified according to Soil Taxonomy Second Edition, 1999
Updated competing series section 4/10/08, CEM
ADDITIONAL DATA: S79AZ-003-5