LOCATION TERRO              WY
Established Series
GFK/CAP/CJH
12/2005

TERRO SERIES


The Terro series consists of well drained soils that are moderately deep to soft bedrock. They formed on gently to steeply sloping hills, ridges, fan remnants, terraces and plateaus in residuum, alluvium, colluvial slopewash or eolian materials derived primarily from soft sandstone. Slopes are 0 to 30 percent. The mean annual precipitation is about 12 inches, and the mean annual air temperature is about 47 degrees F.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Ustic Haplargids

TYPICAL PEDON: Terro sandy loam--on west facing slope of 10 percent-rangeland. (Colors are for dry soil unless otherwise stated)

A--0 to 6 inches; light brownish gray (10YR 6/2) sandy loam, dark grayish brown (10YR 4/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many fine and very fine roots; neutral (pH 7.2); clear smooth boundary. (4 to 6 inches thick)

Bt--6 to 20 inches; pale brown (10YR 6/3) sandy loam, brown (10YR 4/3) moist; weak medium prismatic structure parting to weak medium subangular blocky; slightly hard, very friable, nonsticky and nonplastic; many fine roots; common faint clay bridges between sand grains; slightly alkaline (pH 7.4); clear wavy boundary. (6 to 14 inches thick)

Bk1--20 to 24 inches; pale brown (10YR 6/3) sandy loam, brown (10YR 4/3) moist; weak fine subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; few fine and medium roots; slightly effervescent, calcium carbonate disseminated and as few distinct masses; moderately alkaline (pH 8.0); clear wavy boundary. (0 to 7 inches thick)

Bk2--24 to 34 inches; light gray (10YR 7/2) sandy loam, light brownish gray (10YR 6/2) moist; massive; slightly hard, friable, nonsticky and nonplastic; strongly effervescent, calcium carbonate disseminated and as common, distinct, irregularly shaped masses; moderately alkaline (pH 8.4); gradual wavy boundary. (10 to 25 inches thick)

Cr--34 to 60 inches; soft, calcareous sandstone.

TYPE LOCATION: Weston County, Wyoming; 870 feet north and 150 feet east of the southwest corner of sec. 27, T. 44 N., R. 68 W. Buck Creek Quadrangle. 43 degrees 45 minutes 24 seconds north latitude and 105 degrees 1 minute 9 seconds west longitude.

RANGE IN CHARACTERISTICS: Depth to horizons of continuous calcium carbonate accumulation ranges from 15 to 22 inches. Depth to the base of the argillic horizon is 10 to 22 inches. Depth to bedrock ranges from 20 to 40 inches. Rock fragments as channers range from 0 to 10 percent. The soil is dry in the moisture control section more than half the time cumulative that the soil temperature at a depth of 20 inches is 41 degrees F., which occurs about April 21-27, and is dry in all parts of the moisture control section for at least 60 consecutive days from July 15 to October 25 and for at least 90 cumulative days during this period. The mean annual soil temperature is 48 to 51 degrees F., and the soil temperature at a depth of 20 inches is 41 degrees F. or more for 175 to 192 days.

The A horizon has hue of 2.5Y or 10YR, value of 5 to 7 dry, 3 to 5 moist, and chroma 1 to 3. It has textures of sandy loam, fine sandy loam or very fine sandy loam. Reaction is neutral or slightly alkaline.

The Bt horizon has hue of 2.5Y, 10YR or 7.5YR, value of 5 to 7 dry, 3 to 5 moist, and chroma of 2 to 4. It is sandy loam or fine sandy loam with clay ranging from 10 to 18 percent. Oriented clay occurs as bridges holding mineral grains together. Reaction is neutral or slightly alkaline.

The Bk horizon has hue of 7.5YR to 2.5Y, value of 5 to 7 dry, 4 to 6 moist, and chroma of 2 to 4. Texture is sandy loam, fine sandy loam, loamy sand or loamy fine sand. Reaction is slightly alkaline to strongly alkaline.

The C horizon, when present, has hue of 10YR or 2.5Y, value of 5 or 6 dry, 4 or 5 moist, and chroma of 3 or 4. Texture is fine sandy loam, sandy loam, loamy sand or loamy fine sand. Reaction is neutral or slightly alkaline. Calcium carbonate is 0 to 4 percent.

The Cr horizon is soft calcareous sandstone or sandstone interbedded with shale.

COMPETING SERIES: These are the Betonnie, Bijou, Tintero and Vonalee series. It is assumed the Terry series is competing pending an update of the classification. Betonnie, Bijou, Tintero and Vonalee soils lack a paralithic contact at depths less than 40 inches. Terry soils are moist in some or all parts for 60 consecutive days following July 15 and are moist in some parts for at least 90 cumulative days when the soil temperature at a depth of 20 inches is 41 degrees F. or more.

GEOGRAPHIC SETTING: The Terro soils are on nearly level to steeply sloping hills, ridges, fan remnants, terraces and plateaus. Slopes range from 0 to 30 percent. The soils formed in residuum, alluvium and colluvium. Elevation is 3600 to 6,500 feet. The average annual precipitation is 10 to 14 inches, and the average annual temperature is 47 to 51 degrees F. The frost-free season is 105 to 130 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Vonalee and the Keeline, Taluce and Turnercrest soils. Keeline soils lack a paralithic contact at depths of less than 40 inches. Taluce and Turnercrest lack an argillic horizon and are calcareous throughout.

DRAINAGE AND PERMEABILITY: Well drained, low to high runoff, moderately rapid permeability.

USE AND VEGETATION: These soils are used mainly as rangeland. Native vegetation consists of needleandthread, blue grama, prairie sandreed, and threadleaf sedge.

DISTRIBUTION AND EXTENT: Powder River Basin and adjacent areas of eastern Wyoming. The series is of moderate extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado

SERIES ESTABLISHED: Weston County, Wyoming; 1983.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - 0 to 6 inches (A)

Argillic horizon - 6 to 20 inches (Bt)

Paralithic contact - 34 inches (Cr)

SIR- WY1148

MLRR- G


National Cooperative Soil Survey
U.S.A.