LOCATION TONCANA                 UT

Established Series
Rev. EJ-JAC-KLS
03/2023

TONCANA SERIES

The Toncana series consists of deep, well drained soils that formed in material weathered from conglomerate of sandstone and quartzite. These soils are on north- and east-facing mountain sides. Slopes are 40 to 60 percent. The mean annual precipitation is about 560 mm and the mean annual air temperature is about 6 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Pachic Ultic Argixerolls

TYPICAL PEDON: Toncana loam, rangeland. (Colors are for moist soil unless otherwise noted.)

Oi--0 to 3 cm; loose leaves and twigs. (0 to 5 cm thick)

A1--3 to 13 cm; very dark brown (10YR 2/2) loam, very dark grayish brown (10YR 3/2) dry; moderate medium granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine, fine and common medium roots; many fine and very fine pores; 10 percent gravel; moderately acid (pH 5.8); clear wavy boundary.

A2--13 to 33 cm; dark reddish brown (5YR 3/3) loam, brown (7.5YR 4/3) dry; moderate medium granular structure; soft, friable, slightly sticky and slightly plastic; many very fine, fine and few medium and coarse roots; many very fine, fine and few medium pores; 10 percent gravel; moderately acid (pH 5.8); clear wavy boundary.

A3--33 to 63 cm; dark reddish brown (5YR 3/3) loam, brown (7.5YR 4/3) dry; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine, common fine and few coarse roots; many very fine and few fine pores; 20 percent gravel; moderately acid (pH 6.0); clear wavy boundary. (Combined thickness of the A1, A2 and A3 horizons - 50 to 85 cm)

Bt1--63 to 83 cm; dark reddish brown (5YR 3/4) gravelly clay loam, reddish brown (5YR 5/4) dry; moderate fine subangular blocky structure; hard, firm, sticky and plastic; few very fine, fine and medium roots; common very fine and few fine pores; common thin clay films as bridges and in pores; 40 percent gravel and 10 percent cobbles; moderately acid (pH 6.0); gradual wavy boundary.

Bt2--83 to 103 cm; dark red (2.5YR 3/6) very gravelly clay loam, reddish brown (5YR 5/4) dry; moderate medium subangular blocky structure; hard, firm, sticky and plastic; few fine and medium roots; common very fine pores; continuous thin clay films on faces of peds; 35 percent gravel and 20 percent cobbles; moderately acid (pH 6.0); clear wavy boundary. (Combined thickness of Bt1 and Bt2 horizons - 40 to 100 cm)

Bt3--103 to 154 cm; dark red (2.5YR 3/6) very gravelly clay loam, reddish brown (5YR 5/4) dry; moderate medium subangular blocky structure; hard, firm, sticky and plastic; few fine and medium roots; few very fine pores; continuous thin clay films on faces of peds; 35 percent gravel and 20 percent cobbles; moderately acid (pH 6.0).

TYPE LOCATION: Morgan County, Utah; about 2 km south and 6 km east of Morgan County Courthouse; about 410 meters east and 150 meters north of the southwest corner of sec. 3, T.3N., R.3E.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature--6 to 8 degrees C
Mean summer soil temperature--17 to 18 degrees C
The soils are usually moist but are dry for 65 to 85 consecutive days during late summer.
Combined thickness of A and Bt horizons--140 to more than 150 cm over bedrock
Base saturation--less than 75 percent in part or all parts above a depth of 75 cm
Rock fragment content in the A horizon--0 to 20 percent

Particle-size control section:
Clay content--30 to 35 percent
Rock fragment content--35 to 60 percent, consisting of rounded quartzite gravel and cobbles

A horizons
Hue--10YR through 5YR
Value--3 or 4 dry, 2 or 3 moist
Chroma--2 or 3 dry and moist
Reaction--pH 5.6 to 6.5
Thickness--50 to 75 cm

B2t horizon
Hue--5YR through 2.5YR (7.5YR in the upper part in some pedons)
Value--5 or 6 dry, 3 or 4 moist
Chroma--4 through 6 dry, 3 through 6 moist
Texture--gravelly clay loam to very cobbly clay loam
Structure--weak to moderate, fine to medium subangular blocky and weak medium prismatic structure that parts to moderate medium subangular blocky
Thickness--90 to 100 cm or more

COMPETING SERIES: These are the Durst, Henhoit and Smarts series. Burst and Henhoit soils have mollic epipedons less than 50 cm thick. Smarts soils have 7.5YR or 10YR hue in all parts of the Bt horizon. They are no redder than 7.5YR in any part.

GEOGRAPHIC SETTING:
Landform--slightly concave, north- and east-facing mountain slopes
Elevations--1850 to 3000 meters
Slope--40 to 60 percent
Parent material--residuum and local alluvium weathered from conglomerate of sandstone and quartzite
Climate--moist subhumid
Mean annual precipitation--460 to 640 mm
Mean annual air temperature--5 to 7 degrees C
Mean summer air temperature--15 to 16 degrees C
Frost-free period--70 to 75 days

GEOGRAPHICALLY ASSOCIATED SOILS: None listed.

DRAINAGE AND PERMEABILITY: Well drained-medium runoff moderately slow permeability.

USE AND VEGETATION: Toncana soils are used for range, wildlife habitat, and waterhead. The present native vegetation is oakbrush, snowberry, ninebark, wild sweetpea, native bluegrass, yarrow, mountain bromegrass, big sagebrush, slender wheatgrass, and Oregon grape.

DISTRIBUTION AND EXTENT: Toncana soils are of small extent in northern Utah; MLRA 47.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Morgan County, Morgan Area, Utah, 1974.

REMARKS: Converted to metric and O horizons were updated to start at zero. Competing series section was not updated. 02/2023

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National Cooperative Soil Survey
U.S.A.