LOCATION TSCHICOMA NMTentative Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Pachic Argiustolls
TYPICAL PEDON: Tschicoma loam--on the footslope of a valley side sloping 5 percent to the southwest at 8,974 foot elevation-mountain meadow. (Colors are for dry soil unless otherwise noted. When described on August 29, 2000, the soil was dry from 0 to 8 inches and moist from 8 to 92 inches.)
Oe-0 to 2 inches, moderately decomposed needles and twigs; clear smooth boundary. (1 to 3 inches thick)
A1--2 to 4 inches; very dark gray (10YR 3/1) loam, black (10YR 2/1) moist; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; common fine and many very fine roots; 1 percent gravel, neutral (pH 6.6); clear wavy boundary. (2 to 6 inches thick)
A2--4 to 12 inches; very dark grayish brown (10YR 3/2) gravelly loam, black (10YR 2/1) moist; moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; common fine and many very fine roots; common medium and fine irregularly shaped pores; 20 percent gravel, neutral (pH 6.7); clear wavy boundary. (4 to 13 inches thick)
BA--12 to 21 inches; brown (10YR 5/3) sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few fine and common very fine roots; common coarse, few medium and few fine tubular pores; 10 percent gravel, neutral (pH 6.8); clear smooth boundary. (8 to 13 inches thick)
Bt1--21 to 37 inches; light yellowish brown (10YR 6/4) gravelly clay loam, dark yellowish brown (10YR 4/4) moist; weak coarse prismatic structure parting to moderate medium subangular blocky; hard, firm, slightly sticky and slightly plastic; few fine and few very fine roots; few very coarse, few coarse, and few fine tubular pores; common distinct clay films on faces of peds; 20 percent gravel, neutral (pH 6.8); clear wavy boundary. (9 to 20 inches thick)
Bt2--37 to 54 inches; light brown (7.5YR 6/4) clay loam, brown (7.5YR 5/3) moist; strong medium angular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine roots; few very fine tubular pores; common distinct and few faint clay films on faces of peds; 5 percent gravel, neutral (pH 6.8); clear smooth boundary. (5 to 29 inches thick)
C1--54 to 85 inches; light brown (7.5YR 6/4) sandy loam, strong brown (7.5YR 5/6) moist; massive; slightly hard, friable, slightly sticky and nonplastic; 5 percent gravel, neutral (pH 6.9); clear smooth boundary. (31 to 37 inches thick)
C2--85 to 92 inches; pink (7.5YR 7/3) sandy loam, reddish yellow (7.5YR 6/6) moist; single grain; loose, nonsticky and nonplastic; 10 percent gravel; neutral (pH 6.8).
TYPE LOCATION: Bandelier National Monument, Sandoval County, about 7 miles west-southwest of Los Alamos; USGS Bland 7.5 minute topographic quadrangle; Latitude 35 degrees 50 minutes 55.2 seconds North and Longitude 106 degrees 25 minutes 30.37 seconds West, NAD 27.
RANGE IN CHARACTERISTICS:
(Depths given are measured from the mineral soil surface)
Soil moisture - The soil moisture control section (SMCS) is moist in all parts from January to May and intermittently moist in some part from June to December. The SMCS is dry in all parts less than 40 percent of the time and dry in some or all part more than 105 cumulative days when the soil temperature at 20 inches is above 41 degrees F. The soil moisture regime is typic ustic.
Mean annual soil temperature - 43 to 47 degrees F.
Depth to base of mollic epipedon - 16 to 22 inches
Depth to base of argillic horizon - 40 inches or more
Lithology of rock fragments - dacite, latite, and rhyolitic tuff
Particle-size control section (weighted averages)
Silicate clay content: 20 to 35 percent
Sand content: 35 to 55 percent
Fine sand or coarser content: 35 to 45 percent
Rock fragment content: 5 to 20 percent
A1 horizon
Value: 3 to 5 dry
Chroma: 1 or 2, dry or moist
Rock fragments: 0 to 10 percent gravel
A2 horizon (includes an A3 horizon in some pedons)
Hue: 7.5YR or 10YR
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 2 or 3 dry, 1 to 3 moist
Texture: gravelly loam, sandy loam, or loam
Rock fragments: 10 to 20 percent gravel
BA horizon (not present in some pedons)
Texture: sandy loam or loam
Clay content: 10 to 18 percent
Rock fragments: 5 to 15 percent gravel
Bt1 horizon
Hue: 7.5YR or 10YR
Value: 4 to 6 dry, 3 or 4 moist
Chroma: 2 to 6, dry or moist
Texture: gravelly clay loam, cobbly sandy clay loam, clay loam, loam, or sandy clay loam
Clay content: 20 to 30 percent
Rock fragments: total range is 5 to 20 percent
5 to 15 percent gravel
0 to 10 percent cobbles
Lower Bt horizons
Hue: 7.5YR or 10YR
Value: 4 to 6 dry, 2 to 5 moist
Chroma: 2 to 4 dry, 2 to 6 moist
Texture: gravelly clay loam, clay loam, sandy clay loam, cobbly sandy loam, or sandy loam
Clay content: 18 to 40 percent
Rock fragments: total range is 5 to 20 percent
5 to 15 percent gravel
0 to 10 percent cobbles
C horizons
Hue: 7.5YR or 10YR
Value: 5 to 7 dry, 4 to 6 moist
Chroma: 3 to 6 dry
Texture: gravelly loamy coarse sand, coarse sandy loam or sandy loam
Clay content: 6 to 15 percent
Rock fragments: 5 to 25 percent, mostly gravel
COMPETING SERIES: These are the Bowbells, Cambern, Carfall, Center Creek, Chugcreek, Detra, Fiesta, Flaxton, Gordo, Hereford, Hesperus, Jaythree, Laceycreek, Ohwiler, Pachel, Peta, Schauson, Todacheene and Weed series. Bowbells, Flaxton, Fiesta, Hereford, Pachel and Weed soils have continuous horizons of visible calcium carbonate accumulation. Cambern soils have a lithic contact at 20 to 40 inches. Carfall, Jaythree, and Laceycreek soils do not have rock fragments of latite, dacite, or tuff. Center Creek, Hesperus, and Peta soils have redoximorphic features within 60 inches. Chugcreek soils have a lithic contact at depths of 20 to 40 inches. Detra soils have a lithic contact between 40 and 60 inches. Gordo soils have a paralithic contact at 40 to 60 inches. Ohwiler soils have less than 35 percent fine and coarser sand in the argillic horizon. Schauson soils have moisture control sections that are dry for 50 to 55 percent of the time when the soil temperature is above 41 degrees F. Todacheene soils have rock fragments of basalt and basaltic tuff in the lower Bt horizons..
GEOGRAPHIC SETTING: Tschicoma soils are on toeslopes and footslopes of valley sides and undulating plateaus. They formed in slope alluvium derived from Tertiary age latite and dacite, and Quaternary age rhyolitic tuff. Slopes are 2 to 20 percent. Elevation ranges from 7,800 to 9,200 feet. The mean annual precipitation is 20 to 28 inches with about 40 percent falling as rain from high-intensity convective thunderstorms between July and September. The mean annual air temperature is 41 to 45 degrees F. The frost-free period is 100 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hoxoh, Jemez, Lucito, and Tranquilar soils. Hoxoh soils are ashy-skeletal, do not have argillic horizons, and occur on summits and shoulders of interfluves on undulating plateaus. Jemez soils are moderately deep, do not have mollic epipedons, and occur on summits and shoulders of interfluves on undulating plateaus. Lucito soils are clayey-skeletal and occur on toeslopes and footslopes of mountains. Tranquilar soils are very-fine, have smectitic mineralogy, and occur on flood plains.
DRAINAGE AND PERMEABILITY: Well drained; moderate runoff; permeability is moderate or moderately slow
USE AND VEGETATION: Tschicoma soils are used for timber production and recreation. Present vegetation is orchardgrass, Thurber's fescue, Parry's oatgrass and scattered ponderosa pine and Rocky Mountain Douglas fir.
DISTRIBUTION AND EXTENT: Tschicoma soils are of small extent on the Jemez Volcanic Field part of the Southern Rocky Mountains province in northcentral New Mexico. The MLRA is 48A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES PROPOSED: Sandoval County, New Mexico; Bandelier Soil Survey Update; 2000. Tschicoma is a place name.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon (Pachic feature) - The zone from 2 to 21 inches. (A1, A2, and BA horizons)
Argillic horizon - The zone from 21 to 54 inches. (Bt1 and Bt2 horizons)
Particle-size control section - The zone from 21 to 41 inches (Bt1 and part of the Bt2 horizon)
Keys to Soil Taxonomy: Series classified according to Soil Taxonomy, 2nd Edition, 1999.
This series was originally proposed in the Rio Arriba Area, New Mexico. It was dropped during the correlation of Rio Arriba. It is re-proposed in the Bandelier Area with a simliar series concept. However, any connection to the soil in the Rio Arriba area is removed.