LOCATION AMTOFT                  UT+NV

Established Series
Rev. RLT/TER/MJD/JBF
03/2012

AMTOFT SERIES

The Amtoft series consists of shallow, well drained and somewhat excessively drained soils formed in residuum and colluvium derived from calcareous sedimentary rocks. Amtoft soils are on hills, mountains and ridges. Slopes range from 4 to 80 percent. The average annual precipitation is about 250 mm and the mean annual air temperature is about 8 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, carbonatic, mesic Lithic Xeric Haplocalcids

TYPICAL PEDON: Amtoft flaggy loam--rangeland. (Colors are for air-dry soil unless otherwise stated.)

A1--0 to 5 cm; light brownish gray (10YR 6/2) flaggy loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and few fine roots; many fine vesicular pores; 25 percent channery and flaggy rock fragments, mainly on the surface; violently effervescent; moderately alkaline (pH 8.4); abrupt smooth boundary. (3 to 20 cm thick)

ABk--5 to 20 cm; pale brown (10YR 6/3) flaggy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; slightly hard, firm, slightly sticky and moderately plastic; common very fine, few fine and medium roots; few fine and medium pores; 25 percent flaggy and channery rock fragments; few fine masses of secondary calcium carbonate; violently effervescent; moderately alkaline (pH 8.4); clear wavy boundary. (0 to 15 cm thick)

Bk1--20 to 30 cm; very pale brown (10YR 8/3) flaggy loam, pale brown (10YR 6/3) moist; massive; slightly hard, friable, slightly sticky and moderately plastic; common very fine, few fine and medium roots; few fine and very fine pores; 25 percent flaggy rock fragments; common masses of secondary calcium carbonate on the bottom of rock fragments and on peds and in fine threads; violently effervescent; strongly alkaline (pH 8.8); clear smooth boundary. (8 to 15 cm thick)

Bk2--30 to 43 cm; very pale brown (10YR 8/3) extremely flaggy loam, very pale brown (10YR 7/3) moist; massive; soft, friable, slightly sticky and slightly plastic; few very fine roots; few very fine pores; 70 percent rock fragments with 2 mm thick lime coating on bottom, common masses of secondary calcium carbonate on the bottom of rock fragments and on peds and in fine threads; violently effervescent; strongly alkaline (pH 8.8); abrupt smooth boundary. (8 to 15 cm thick)

R--43 to 48 cm; fractured limestone.

TYPE LOCATION: Sanpete County, Utah; about 1/4 mile northeast of the Manti Temple; about 1,500 feet east and 1,600 feet north of the southwest corner of sec. 6, T. 18 S., R. 3 E., USGS Manti 7.5 minute quadrangle, latitude 39 degrees 16 minutes 30 seconds N and longitude 111 degrees 37 minutes 46 seconds W; NAD 83.

RANGE IN CHARACTERISTICS:
Soil Moisture: Usually dry, typically for 70 to 85 consecutive days during the summer; moist in winter and early spring; aridic bordering xeric soil moisture regime.
Mean annual soil temperature: 8 to 15 degrees C.
Thickness of calcic horizon: 15 to 28 cm.
Depth to bedrock: 25 to 50 cm.
Calcium carbonate equivalent: More than 40 percent, including the calcium carbonate in the rock fragments of less than 20 mm size, between a depth of 25 cm and bedrock.

Particle-size control section - Average clay content: 12 to 27 percent.
Rock fragments: Averages 35 to 60 percent.

A and ABk horizons; Bw horizons (when present):
Hue: 2.5Y, 10YR, or 7.5YR.
Value: 5 to 7 dry, 3 to 6 moist. (The value of 5.5 or less dry and 3.5 or less moist occurs within 10 cm of the surface.)
Chroma: 2 through 4, dry or moist.
Reaction: Slightly alkaline to strongly alkaline.
Calcium carbonate equivalent: 10 to 70 percent, in the less than 2mm fraction.
Other features: Some pedons have Bw horizons with colors and textures similar to the A horizon.

Bk1 horizon:
Hue: 2.5Y, 10YR or 7.5YR.
Value: 5 to 8 dry, 4 to 7 moist.
Chroma: 2 to 4, dry or moist.
Texture: Loam, sandy loam or fine sandy loam.
Clay content: 12 to 27 percent.
Rock fragments: Averages 15 to 35 percent with sub-horizons in some pedons containing up to 60 percent flagstones, cobbles, or gravel.
Structure: Subangular blocky or is massive.
Consistence: Soft to slightly hard, very friable or friable, sticky to slightly sticky and slightly plastic or plastic.
Reaction: Moderately alkaline or strongly alkaline.
Calcium carbonate equivalent: 20 to 80 percent, in the less than 2mm fraction.
Electrical conductivity (EC): 0 to 4 mmhos/cm.

Bk2 horizon:
Hue: 2.5Y, 10YR or 7.5YR.
Value: 5 to 8 dry, 4 to 7 moist.
Chroma: 2 to 4, dry or moist.
Texture: Loam, sandy loam or fine sandy loam.
Clay content: 12 to 27 percent.
Rock fragments: Averages 55 to 80 percent flagstones, cobbles, or gravel.
Structure: Subangular blocky or is massive.
Consistence: Soft to slightly hard, very friable or friable, sticky to slightly sticky and slightly plastic or plastic.
Reaction: Moderately alkaline or strongly alkaline.
Calcium carbonate equivalent: 20 to 80 percent, in the less than 2mm fraction.
Electrical conductivity (EC): 0 to 4 mmhos/cm.

COMPETING SERIES: These are the Pookaloo and Tecomar series.

Pookaloo soils are dry longer than 85 days in the summer. Tecomar soils have silt loam textures in the fine earth fraction.

GEOGRAPHIC SETTING: Amtoft soils are on crests and backslopes of hills, mountains and ridges. They formed in colluvium, residuum and local alluvium derived from calcareous sedimentary rocks. These soils occur at elevations of 1,295 to 2,700 meters in a semiarid climate. Slopes range from 4 to 80 percent. Mean annual temperature ranges from 7 to 10 degrees C. Average annual precipitation ranges from 200 to 300 mm in Utah and ranges to 360 mm in Nevada. The freeze-free period ranges from 100 to 160 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arapien, Borvant, Lizzant, Lodar, Sanpete and Sigurd soils. Arapien, Sanpete and Sigurd soils are more than 50 cm deep to bedrock. Borvant, Lizzant and Lodar soils have mollic epipedons.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained and somewhat excessively drained; medium to very high runoff; high saturated hydraulic conductivity.

USE AND VEGETATION: These soils are used for livestock grazing and wildlife habitat. Native potential native vegetation is mainly bluebunch wheatgrass, salmon wildrye, Indian ricegrass, needleandthread, black sagebrush and scattered Utah juniper.

DISTRIBUTION AND EXTENT: Western Utah and eastern Nevada. These soils are extensive. The series concept and main acreage is in MLRA 28A, while other acreage occurs in MLRA 28B.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona

SERIES ESTABLISHED: Sanpete Area, Utah, 1971.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the surface of the soil to 18 cm (A1 and part of the ABk horizons).
Calcic horizon - The zone from 20 to 43 cm (Bk1, Bk2 horizons).
Lithic contact - The boundary with hard bedrock at 43 cm (R layer).
Particle-size control section - The zone from 25 to 43 cm (lower part of the Bk1 and the Bk2 horizons).

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National Cooperative Soil Survey
U.S.A.