LOCATION KOHATK AZEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, carbonatic, thermic Lithic Haplocalcids
TYPICAL PEDON: Kohatk very cobbly fine sandy loam - rangeland (colors are for dry soil unless otherwise noted).
A--0 to 1 inch; light brown (7.5YR 6/4) very cobbly fine sandy loam, brown (7.5YR 4/4) moist; weak thin platy structure; soft, friable, slightly sticky and slightly plastic; few fine roots; common fine interstitial and tubular pores; 35 percent cobble and 20 percent gravel; slightly effervescent; moderately alkaline (pH 8.2); abrupt smooth boundary (1 to 2 inches thick).
Bk1--1 to 7 inches; light brown (7.5YR 6/4) very cobbly loam, brown (7.5YR 4/4) moist; weak fine and medium subangular blocky structure; soft, friable, slightly sticky and slightly plastic; few fine roots; common fine interstitial and tubular pores; many calcium carbonate threads; 40 percent cobble; violently effervescent; moderately alkaline (pH 8.4); clear wavy boundary (5 to 10 inches thick).
Bk2--7 to 10 inches; light brown (7.5YR 6/4) very cobbly loam, brown (7.5YR 5/4) moist; weak fine subangular blocky structure; soft, friable, slightly sticky and slightly plastic; few fine roots; many distinct continuous calcium carbonate coatings on rock fragments; many rounded calcium carbonate masses; 45 percent cobble; violently effervescent; moderately alkaline (pH 8.4); abrupt wavy boundary (5 to 10 inches thick).
R--10 inches; limestone; 1/2 inch thick strongly cemented calcium carbonate cap.
TYPE LOCATION: Pima County, Arizona; latitude 32 degrees, 37 minutes, 2 seconds North and longitude 112 degrees, 08 minutes, 25 seconds West. 1500 feet West and 1000 feet South of the Northeast corner of Section 34, T. 9 S., R. 2 E.
RANGE IN CHARACTERISTICS:
Soil moisture: Intermittently moist in some part of the soil moisture control section during December - February and for more than 20 days cumulative during July - September. Driest during May and June. Typic aridic moisture regime.
Soil temperature: 69 to 72 degrees F.
Rock fragments: 35 to 60 percent cobble and gravel on the surface and in the control section
Depth to bedrock: 6 to 20 inches
Reaction: mildly to moderately alkaline
Clay Content: 8 to 18 percent in the control section
Calcium carbonate equivalent: ranges from 15 to 60 percent; averages more than 40 percent in the control section
A and B horizon
Hue: 7.5YR, 10YR
Value: 5 through 7 dry, 4 through 6 moist
Chroma: 2 through 4, dry or moist
Texture: fine sandy loam, loam
COMPETING SERIES: These are the Helkitchen (NV) and Zeheme (NV) series. Helkitchen and Zeheme soils are in the Mohave Desert and are moist in the soil moisture control section for less than 20 days cumulative between July and September.
GEOGRAPHIC SETTING: The Kohatk soils are on hills. Slopes range from 10 to 45 percent. These soils formed in calcareous mixed slope alluvium, residuum and colluvium mainly from limestone. Elevation ranges from 2,000 to 3,500 feet. The mean annual precipitation is 10 to 13 inches. The mean annual air temperature ranges from 67 to 70 degrees F. The frost-free period is about 240 to 260 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Stagecoach and Vado soils. Stagecoach and Vado soils are very deep.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderate permeability.
USE AND VEGETATION: Kohatk soils are used for livestock grazing, wildlife habitat and mining. Vegetation includes paloverde, slim tridens, red grama, desert zinnia, jojoba, white brittlebush and ocotillo.
DISTRIBUTION AND EXTENT: This series is of moderate extent in Southern Arizona. MLRA is 40.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Pima County, Arizona; Soil survey of Tohono O'odham Indian Reservation, AZ, Parts of Maricopa, Pima and Pinal Counties; 1993.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 1 inch (A horizon)
Calcic horizon - The zone from 1 to 10 inches (Bk1, Bk2 horizons)
Lithic contact - The boundary at 10 inches (R horizon)
Classified according to Soil Taxonomy Second Edition, 1999
Updated competing series section 3/20/08, CEM