LOCATION MARIANO COEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, carbonatic, mesic Typic Haplocalcids
TYPICAL PEDON: Mariano very fine sandy loam, on a south facing, 4 percent slope in rangeland at an elevation of 5,260 feet. (Colors are for dry soil unless otherwise noted.) When described on July 20, 1998 the soil was dry.
A1--0 to 3 inches; brown (7.5YR 5/4) very fine sandy loam, brown (7.5YR 4/3) moist; weak, coarse platy structure; soft, very friable, nonsticky and nonplastic; common fine roots throughout; strongly effervescent; 2 percent calcium carbonate; 5 percent gravel; moderately alkaline (pH 8.0); clear smooth boundary. (2 to 6 inches thick)
A2--3 to 11 inches; light brown (7.5YR 6/4) very fine sandy loam, brown (7.5YR 5/4) moist; weak medium subangular blocky structure; soft, friable, nonsticky and nonplastic; many fine roots throughout; common fine discontinuous tubular pores; strongly effervescent; 14 percent calcium carbonate; 10 percent gravel; moderately alkaline (pH 8.2); gradual wavy boundary. (2 to 15 inches thick)
2Bk1--11 to 19 inches; pink (7.5YR 7/3) extremely gravelly coarse sandy loam, light brown (7.5YR 6/4) moist; weak medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; common fine roots throughout; common fine discontinuous tubular pores; many soft masses of carbonate throughout; violently effervescent; 41 percent calcium carbonate; 80 percent gravel, 2 percent cobbles, and 1 percent stones; moderately alkaline (pH 8.4); clear wavy boundary. (6 to 15 inches thick)
2Bk2--19 to 29 inches; white (7.5YR 8/1) extremely gravelly fine sandy loam, light gray (7.5YR 7/1) moist; massive; very hard, very firm, nonsticky and nonplastic; few fine roots matted around stones; many hard masses of carbonate throughout; violently effervescent; 68 percent calcium carbonate; 80 percent gravel, 5 percent cobbles, and 1 percent stones; moderately alkaline (pH 8.4); gradual wavy boundary. (4 to 16 inches thick)
2Bkn--29 to 51 inches; white (7.5YR 8/1) extremely gravelly sandy loam, light gray (7.5YR 7/1) moist; massive; hard, very firm, nonsticky and nonplastic; few fine roots matted around stones; many hard masses of carbonate throughout; violently effervescent, 34 percent calcium carbonate; 1 percent gypsum; SAR 16; 45 percent gravel, 20 percent cobbles, and 5 percent stones; moderately alkaline (pH 8.4); clear wavy boundary. (0 to 20 inches thick)
2Bkny1--51 to 62 inches; light brown (7.5YR 6/3) extremely gravelly sandy loam, brown (7.5YR 5/3) moist; massive; loose, loose, nonsticky and nonplastic; few fine roots matted around stones; many hard masses of carbonate throughout; moderately effervescent; 23 percent calcium carbonate; 6 percent gypsum; SAR, 20; 55 percent gravel, 20 percent cobbles, and 5 percent stones; moderately alkaline (pH 8.2); gradual wavy boundary. (0 to 20 inches thick)
2Bkny2--62 to 84 inches; brown (10YR 5/3) extremely cobbly sandy loam, brown (10YR 4/3) moist; massive; loose, loose, nonsticky and nonplastic; few soft masses of gypsum under rocks; strongly effervescent; 14 percent calcium carbonate; 3 percent gypsum; SAR, 18; 35 percent gravel, 20 percent cobbles, and 5 percent stones; moderately alkaline (pH 8.4); gradual wavy boundary. (0 to 30 inches thick)
2Bkn--84 to 108 inches; brown (10YR 5/3) extremely cobbly loamy sand, brown (10YR 4/3) moist; massive; loose, loose, nonsticky and nonplastic; strongly effervescent; 13 percent calcium carbonate; SAR, 19; 35 percent gravel, 20 percent cobbles, and 5 percent stones; strongly alkaline (pH 8.6)
TYPE LOCATION: Montezuma County, Colorado; about 3 miles southwest of Ute Mountain; located about 2,600 feet west and 1,100 feet north of the southeast corner of sec. 12, T. 33 1/2 N., R. 20 W.; Mariano West, Colorado, USGS quad; lat. 37 degrees 12 minutes 19 seconds N. and long. 108 degrees 54 minutes 32 seconds W., NAD 27
RANGE IN CHARACTERISTICS:
Soil moisture: Typic aridic moisture regime.
Mean annual soil temperature: 54 to 58 degrees F
Depth to calcic horizon: 10 to 30 inches
Depth to gypsum accumulations: 50 or more inches
Particle-size control section (weighted average):
Clay content: 10 to 18 percent
Rock fragments: 35 to 80 percent mainly igneous gravel and cobble
A horizon
Hue: 7.5YR
Value: 5 or 6, 4 or 5 moist
Chroma: 3 to 5
Texture: very fine sandy loam
Clay content: 10 to 20 percent
Rock fragments: 0 to 15 percent, mainly igneous gravel
Calcium carbonate equivalent: 1 to 14 percent
Reaction: slightly to moderately alkaline
2Bk1 horizon
Hue: 7.5YR
Value: 6 or 7, 5 or 6 moist
Chroma: 3 to 5
Texture: loams, sandy loam, fine sandy loam or coarse sandy loam
Clay content: 10 to 18 percent
Rock fragments: 15 to 85 percent, mainly igneous gravel
Calcium carbonate equivalent: 15 to 45 percent
Reaction: moderately alkaline
2Bk2 horizon
Hue: 7.5YR
Value: 7 or 8, moist or dry
Chroma: 1 or 2
Texture: sandy loam or loam
Clay content: 10 to 18 percent
Rock fragments: 35 to 90 percent
Calcium carbonate equivalent: 30 to 75 percent
SAR: 0 to 5
EC (mmhos/cm): 2 to 16
Reaction: moderately alkaline
2Bkny and 2Bkn horizon
Hue: 7.5YR or 10 YR
Value: 5 or 6, moist or dry
Chroma: 3 or 4
Texture: sandy loam or loam
Clay content: 10 to 18 percent
Rock fragments: 35 to 80 percent,
Calcium carbonate equivalent: 15 to 35 percent
SAR: 1 to 25
Reaction: moderately alkaline
COMPETING SERIES: This is the Dera (UT) series. The Dera soils form in alluvium and lake sediments and lack a discontinuity in parent material. In addition, Dera soils are in the Great Basin Desert (MLRAs 28A, 28B) and have precipitation more evenly distributed throughout the year.
GEOGRAPHIC SETTING:
Parent material: eolian material from sandstone over alluvium from igneous sources
Landform: fan remnants
Slopes: 1 to 6 percent
Elevation: 4,800 to 5,700 feet
Mean annual temperature: 52 to 56 degrees F
Mean annual precipitation: 7 to 10 inches
Precipitation pattern: Uniform with slight dip in May and June and slight increase in July and August.
Frost-free period: 135 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Mack, and Bluechief series. The Mack soils formed in eolian and are on remnant terraces and mesas. The Bluechief soils moderately deep to hard sandstone and are on mesas.
DRAINAGE AND PERMEABILITY: Well drained, low runoff, medium permeability,
USE AND VEGETATION: Rangeland and irrigated cropland. Native vegetation is alkali sacaton, galleta, and fourwing saltbush.
DISTRIBUTION AND EXTENT: Southwest Colorado; MLRA 35; small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona.
SERIES ESTABLISHED: Montezuma County, Colorado, Ute Mountain Area, Colorado and New Mexico, 2005.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Series control section: The zone from 0 to 79 inches.
Particle-size control section: The zone from 10 to 40 inches. (2Bk1, 2Bk2, 2Bkn horizons)
Ochric epipedon: The zone from 0 to 3 inches. (A horizons)
Calcic horizon: The zone from 11 to 51 inches. (2Bk1, 2Bk2, 2Bkn horizons)
Lithologic discontinuity: At the upper boundary of the 2Bk1 horizon. The contact between eolian and alluvial material.
Other features: Some areas approach cementation strengths of petrocalcic horizons, but are not consistent over the area.
ADDITIONAL DATA: National Soil Survey Laboratory sample S99CO-083-06
Classified according to Keys to Soil Taxonomy Ninth Edition, 2003