LOCATION FORT                    CO

Established Series
WSH/LLC/LAN
08/2013

FORT SERIES

The Fort series consists of very deep, well drained soils that formed in mixed eolian material and alluvium. Fort soils are on plains, interfluves, fans, fan remnants, and hills. Slopes range from 0 to 18 percent. Mean annual precipitation is about 330 millimeters (13 inches) and the mean annual temperature is about 11 degrees C (52 degrees F).

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Ustic Calciargids

TYPICAL PEDON: Fort loam - grassland. (Colors are for dry soil unless otherwise noted).

A--0 to 8 centimeters (0 to 3 inches); brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; moderate fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic; many fine roots; slightly alkaline (pH 7.4); abrupt smooth boundary. (3 to 7 inches thick)

Bt--8 to 20 centimeters (3 to 8 inches); brown (10YR 5/3) clay loam, brown (10YR 4/3) moist; weak medium prismatic structure parting to moderate medium subangular blocks; moderately hard, friable, moderately sticky and slightly plastic; few fine roots; 15 percent distinct clay films on faces of peds; slightly alkaline (pH 7.4); clear smooth boundary. (4 to 15 inches thick)

Btk1--20 to 48 centimeters (8 to 19 inches); pale brown (10YR 6/3) clay loam, brown (10YR 5/3) moist; moderate medium prismatic structure parting to moderate coarse subangular blocks; very hard, friable, moderately sticky and slightly plastic; few fine roots; 10 percent distinct clay films on faces of peds; 5 percent fine irregular distinct carbonate masses in matrix; violently effervescent, 5 percent calcium carbonate equivalent; moderately alkaline (pH 8.2); clear smooth boundary.

Btk2--48 to 76 centimeters (19 to 30 inches; light yellowish brown (10YR 6/4) clay loam, yellowish brown (10YR 5/4) moist; moderate medium prismatic structure parting to moderate medium subangular blocks; very hard, friable, moderately sticky and slightly plastic; few fine roots; 5 percent faint clay films on faces of peds; 15 percent medium irregular distinct carbonate masses in matrix; violently effervescent, 5 percent calcium carbonate equivalent; moderately alkaline (pH 8.2); gradual smooth boundary. (Combined thickness of the Btk horizons is 14 to 25 inches)

Bk1--76 to 122 centimeters (30 to 48 inches; very pale brown (10YR 8/2) sandy clay loam, very pale brown (10YR 7/4) moist; weak medium subangular blocky structure; very hard, friable, slightly sticky and slightly plastic; few fine roots; 15 percent fine irregular distinct carbonate masses in matix; violently effervescent, 25 percent calcium carbonate equivalent; moderately alkaline (pH 8.2); gradual smooth boundary. (8 to 29 inches thick)

Bk2--122 to 200 centimeters (48 to 60 inches); light yellowish brown (10YR 6/4) loam, yellowish brown (10YR 5/4) moist; massive; moderately hard, friable, slightly sticky and slightly plastic; 5 percent fine irregular distinct carbonate masses in matrix; violently effervescent, 8 percent calcium carbonate equivalent; moderately alkaline (pH 8.2).

TYPE LOCATION: Lincoln County, Colorado; approximately 9 miles east and 5 miles south of Karval, Colorado; 2,200 feet north and 300 feet west of the southeast corner of Sec. 7, T. 16 S., R. 53 W.; USGS Hubbard Lake, CO quadrangle; UTM zone 13, 631,566 meters E, 4,281,882 meters N; latitude 38 degrees, 40 minutes, 27.4 seconds north and longitude 103 degrees, 22 minutes, 35 seconds west; NAD83.

RANGE IN CHARACTERISTICS:
Soil moisture control section: Moist in some part March through May and is intermittently moist June through September. It is driest December through February
Moisture regime: Aridic bordering on ustic.
Mean annual soil temperature: 9 to 12 degrees C (49 to 54 degrees F.)
Mean summer soil temperature: 18 to 25 degrees C (65 to 78 degrees F.)
Depth to calcareous material: 20 to 51 cm (8 to 20 inches)
Depth to calcic horizon: 51 to 100 cm (20 to 40 inches)
Depth to the base of the argillic horizon: 51 to 100 cm (20 to 40 inches) with the upper part leached of calcium carbonate.

The particle size control section: (weighted average)
Clay content: 18 to 30 percent
Silt content: 20 to 50 percent
Sand content: 20 to 45 percent sand, with 15 to 35 percent fine sand or coarser.
Rock fragments range from 0 to 5 percent, but may range to 15 percent below 100 cm (40 inches).

A horizon:
Hue: 7.5YR to 2.5Y
Value: 4 to 6 dry, 3 or 4 moist
Chroma: 2 to 4
Texture: loam or sandy loam
Reaction: neutral or slightly alkaline.

Bt horizon:
Hue: 10YR or 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2 to 4
Texture: loam or clay loam
Clay content: 18 to 35 percent
Calcium carbonate equivalent: 0 to 1 percent
Reaction: neutral or slightly alkaline.

Btk horizon:
Hue: 10YR to 2.5Y
Value: 5 to 7 dry, 4 to 6 moist
Chroma: 3 or 4
Texture: loam, clay loam, sandy clay loam
Clay content: 18 to 35 percent
Calcium carbonate equivalent: 5 to 25 percent
Reaction: moderately alkaline or strongly alkaline.

The Bk horizon(s): (Bky in some pedons)
Hue: 10YR to 2.5Y
Value: 6 to 8 dry, 5 to 7 moist
Chroma: 3 or 4
Texture: fine sandy loam, sandy loam, loam, silt loam, sandy clay loam, clay loam, or silty clay loam.
Clay content: 10 to 30 percent
Calcium carbonate equivalent: 5 to 30 percent
Reaction: moderately alkaline or strongly alkaline.

COMPETING SERIES: These are the Alvey, Barx, Cabreros, Cerrillos, Clovis, Fernando, Flaco, Horchata, Maysdorf, Millett, Palabria, Progresso, Sanostee, Scholle, Selpats, Solirec, Spenlo, Threetop, Tuweep, and Wineg series.
Alvey soils: have a moisture control section that is dry at least 50 percent of the time when the soil is 5 degrees C (41 degrees F) or warmer.
Barx, Cerrillos, Clovis, Palabria, Solirec, and Spenlo soils: have hues redder than 10YR.
Cabreros and Sanostee soils: have a paralithic contact at depths of 50 to 100 cm (20 to 40 inches).
Fernando soils: are calcareous throughout the argillic horizon.
Flaco, Horchata, Progresso, and Threetop soils: have a lithic contact at depths of 50 to 100 cm (20 to 40 inches).
Maysdorf soils: do not have Btk horizons and do not have a horizon with more than 15 percent calcium carbonate equivalent. They are dry July to September.
Millett, Selpats, and Tuweep soils: have greater than 15 percent rock fragments below the argillic horizon.
Scholle soils: average greater than 15 percent rock fragments in the control section.
Wineg soils: have a moisture control section that is dry in May and June and is 50 cm (20 inches) or less to the base of the argillic horizon.

GEOGRAPHIC SETTING:
Landform: plains, fans, fan remnants, hills, and interfluves
Slopes: 0 to 18 percent
Parent material: mixed eolian material and alluvium
Elevation: 1,219 to 1,981 meters (4,000 to 6,500 feet).
Mean annual precipitation: 254 to 356 millimeters (10 to 14 inches) Wettest period: May through August
Driest period: December through February
Mean annual air temperature: 9 to 12 degrees C (48 to 54 degrees F).
Frost free period: 125 to 170 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Kimera, Olney, Vonid, and Wilid soils. Kimera soils lack argillic horizons. Olney soils have greater than 35 percent fine sand or coarser in the particle size control section. Vonid soils average less than 18 percent clay in the control section. Wilid soils have less than 15 percent fine sand or coarser in the particle size control section.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage: Well drained
Saturated hydraulic conductivity: moderately high

USE AND VEGETATION: These soils are used for rangeland and dry cropland. Native vegetation is mainly blue grama, galleta, buffalograss, western wheatgrass, and sand dropseed. Loamy plains or sandy plains ecological sites.

DISTRIBUTION AND EXTENT: This soil is located in southeastern Colorado. This soil is extensive. LRR G. MLRA 69.

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

SERIES ESTABLISHED: Lincoln County (Lincoln County Area), Colorado, 1996.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Particle size control section: 8 to 58 cm (3 to 23 inches). (Bt, Btk1, and part of the Btk2 horizons)
Ochric epipedon: 0 to 8 cm (0 to 3 inches). (A horizon)
Argillic horizon: 8 to 76 cm (3 to 30 inches). (Bt, Btk1 and Btk2 horizons)
Calcic horizon: 76 to 122 cm (30 to 48 inches).
Aridic moisture regime bordering on ustic.

The Fort series replaces Fort Collins in the Ustic-Aridic moisture regime. The Fort Collins series was reclassified from Ustic Haplargids to Aridic Haplustalfs. The name Fort is coined from Fort Collins. MLRA 69

6/2013 LAN: This revision re-classifies the Fort series to a Calciargid based on laboratory data collected in Lincoln County, and pedon descriptions from Otero, Huerfano, Fremont, and Las Animas Counties.

The assignment of the cation-exchange activity class is supported by lab sample(s) numbers S89CO-073-014.

Taxonomic Version: Eleventh Edition, 2010

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National Cooperative Soil Survey
U.S.A.