LOCATION POTRIO COEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Calcidic Haplustalfs
TYPICAL PEDON: Potrio gravelly silt loam, 1 to 6 percent slopes in basalt. (Colors are for dry soil unless otherwise noted.)
A--0 to 10 centimeters; brown (7.5YR 4/3) gravelly silt loam, very dark brown (7.5YR 2.5/3) moist; 17 percent clay; weak fine granular structure; friable, soft, slightly sticky, slightly plastic; common fine and coarse roots throughout; common very fine irregular pores; 20 percent gravel; noneffervescent; slightly alkaline (pH 7.4); clear smooth boundary. (5 to 25 centimeters thick)
Bt--10 to 38 centimeters; brown (7.5YR 5/4) gravelly silt loam, dark brown (7.5YR 3/4) moist; 22 percent clay; moderate fine and medium subangular blocky structure; friable, moderately hard, moderately sticky, moderately plastic; common fine roots and medium roots throughout; common very fine dendritic tubular pores; 60 percent clay films on faces of peds; 20 percent gravel; noneffervescent; slightly alkaline (pH 7.4); gradual wavy boundary. (13 to 38 centimeters thick)
Btk1--38 to 61 centimeters; light brown (7.5YR 6/3) gravelly silt loam, brown (7.5YR 4/3) moist; 22 percent clay; moderate medium subangular blocky structure; friable, moderately hard, moderately sticky, moderately plastic; common fine and medium roots throughout; common very fine dendritic tubular pores; 60 percent clay films on faces of peds; fine irregular carbonate, finely disseminated throughout and fine threadlike carbonate masses infused into matrix adjacent to pores; 25 percent gravel; strongly effervescent (7 percent calcium carbonate equivalent); slightly alkaline (pH 7.6); gradual wavy boundary. (13 to 51 centimeters thick)
Btk2--61 to 76 centimeters; light brown (7.5YR 6/4) gravelly silt loam, brown (7.5YR 4/4) moist; 20 percent clay; moderate medium subangular blocky structure; friable, moderately hard, moderately sticky, moderately plastic; common fine and medium roots throughout; common very fine dendritic tubular pores; 30 percent clay films on faces of peds; fine threadlike carbonate masses infused into matrix adjacent to pores and fine irregular carbonate, finely disseminated throughout; 30 percent gravel; strongly effervescent (16 percent calcium carbonate equivalent); slightly alkaline (pH 7.8); gradual wavy boundary. (0 to 25 centimeters thick)
Btk3--76 to 91 centimeters; pink (7.5YR 7/3) very cobbly loam, brown (7.5YR 5/3) moist; 18 percent clay; weak fine subangular blocky structure; friable, moderately hard, moderately sticky, moderately plastic; common fine and medium roots throughout; common very fine dendritic tubular pores; 15 percent clay films on faces of peds; fine irregular carbonate masses throughout; 25 percent gravel and 15 percent cobbles; violently effervescent (42 percent calcium carbonate equivalent); moderately alkaline (pH 8.4); gradual wavy boundary. (0 to 25 centimeters thick)
Bk--91 to 107 centimeters; pinkish white (7.5YR 8/2) extremely cobbly sandy loam, light brown (7.5YR 6/3) moist; 14 percent clay; massive; very friable, moderately hard, nonsticky, nonplastic; common fine and medium roots throughout; common very fine dendritic tubular pores; fine irregular carbonate masses throughout; 40 percent gravel and 30 percent cobbles; violently effervescent (50 percent calcium carbonate equivalent); moderately alkaline (pH 8.4); abrupt irregular boundary. (0 to 25 centimeters thick)
R--107 centimeters: fractured basalt.
TYPE LOCATION: Costilla County, Colorado; USGS Sanchez Reservoir topographic quadrangle; UTM 459200 meters E, 4105499 meters N, zone 13, NAD 83.
RANGE IN CHARACTERISTICS:
Soil moisture: The soil moisture regime is aridic bordering ustic.
Mean annual soil temperature: 41 to 46 degrees F (5 to 7.8 degrees C)
Mean summer soil temperature: 63 to 66 degrees F (17.2 to 18.9 degrees C)
Depth to argillic horizon: 2 to 6 inches (5 to 15 centimeters)
Depth to calcic horizon: 10 to 40 inches (25 to 102 centimeters
Depth to lithic contact: 40 to 60 inches (102 to 152 centimeters)
Thickness of argillic horizon: 5 to 11 inches (13 to 28 centimeters) Thickness of calcic horizon: 6 to 12 inches (15 to 30 centimeters)
Rock fragments: 15 to 30 percent subangular basalt gravel and 0 to 5 percent basalt cobbles
Particle-size control section (weighted average):
Clay content: 18 to 32 percent
Sand content: 30 to 52 percent
Rock fragment content: 15 to 35 percent
A horizon(s)
Hue: 7.5YR or 10YR
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3
Texture: gravelly silt loam
Clay content: 12 to 24 percent
Sand content: 20 to 55 percent
Silt content: 35 to 77 percent
Fragment content, total: 15 to 35 percent
Fragment size and content: 15 to 30 percent indurated basalt gravel
0 to 5 percent indurated basalt cobbles
Calcium carbonate equivalent: 0 to 1 percent
Electrical conductivity: 0 to 2 mmhos/cm
Reaction: pH 6.6 to 7.8
Organic matter content: 1.0 to 3.0 percent
Bt horizon(s)
Hue: 7.5YR or 10YR
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 3 or 4
Texture: gravelly loam, gravelly silt loam
Clay content: 18 to 27 percent
Sand content: 20 to 52 percent
Silt content: 35 to 77 percent
Fragment content, total: 15 to 35 percent
Fragment size and content: 15 to 30 percent indurated basalt gravel
0 to 5 percent indurated basalt cobbles
Calcium carbonate equivalent: 0 to 2 percent
Electrical conductivity: 0 to 2 mmhos/cm
Reaction: pH 6.6 to 7.8
Organic matter content: 0.5 to 1.5 percent
Btk horizon(s)
Hue: 7.5YR or 10YR
Value: 6 or 7 dry; 4 or 5 moist
Chroma: 3 or 4
Texture: gravelly silt loam, gravelly clay loam, gravelly loam, very cobbly loam
Clay content: 15 to 30 percent
Sand content: 20 to 52 percent
Silt content: 28 to 77 percent
Fragment content, total: 15 to 60 percent
Fragment size and content: 15 to 35 percent indurated basalt gravel
0 to 25 percent indurated basalt cobbles
Calcium carbonate equivalent: 1 to 45 percent
Electrical conductivity: 0 to 2 mmhos/cm
Reaction: pH 6.6 to 8.4
Organic matter content: 0.0 to 0.8 percent
Bk horizon(s)
Hue: 7.5YR or 10YR
Value: 7 or 8 dry; 6 or 7 moist
Chroma: 2 or 3
Texture: extremely cobbly sandy loam, very cobbly sandy loam
Clay content: 12 to 20 percent
Sand content: 52 to 73 percent
Silt content: 15 to 35 percent
Fragment content, total: 35 to 75 percent
Fragment size and content: 25 to 40 percent indurated basalt gravel
10 to 35 percent indurated basalt cobbles
Calcium carbonate equivalent: 15 to 45 percent
Electrical conductivity: 0 to 2 mmhos/cm
Reaction: pH 7.9 to 9.0
Organic matter content: 0.0 to 0.5 percent
R horizon(s): fractured basalt.
COMPETING SERIES:
These are the
Coyoteflats and
Mantlemine series.
Coyoteflats soils: very deep soils
Mantlemine soils: very deep soils
GEOGRAPHIC SETTING:
Parent material: Slope alluvium derived from basalt
Landform: mesa
Slopes: 1 to 65 percent
Elevation: 7,700 to 9,100 feet
Mean annual air temperature: 37 to 41 degrees F (3.0 to 5.0 degrees C)
Mean annual precipitation: 12 to 16 inches
Precipitation pattern: The soil moisture control section is affected by precipitation in late summer and early fall. The soil is driest from November to March. The soil has the potential to be moist from April to October.
Frost-free period: 85 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: This is the San
Pedro series.
The San Pedro soils are shallow to basalt.
DRAINAGE AND PERMEABILITY: Well drained, low to high runoff (depends on slope of map unit), moderate permeability.
USE AND VEGETATION: The major use is rangeland. Native vegetation includes Wyoming big sagebrush, rabbitbrush, blue grama, prickly pear, broom snakeweed and fringed sagebrush
DISTRIBUTION AND EXTENT: High intermountain valleys of south central Colorado. LLR E, MLRA 51. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Costilla County, Colorado, 2009. The name Potrio is coined.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 0 to 4 inches (0 to 10 centimeters). (A horizons)
Argillic horizon: The zone from 4 to 36 inches (10 to 91 centimeters). (Bt, Btk horizons)
Calcic horizon: The zone from 15 to 42 inches (38 to 107 centimeters). (Btk, Bk horizons)
Lithic contact: 42 inches (107 centimeters).
The assignment of the cation-exchange activity class is inferred from lab data from similar soils in the surrounding area.
Taxonomic Version: Tenth Edition, 2006