LOCATION ANNELLA CO
Established Series
Rev. TWH/KLS
04/2018
ANNELLA SERIES
The Annella series consists of very deep, well drained soils that formed in slope alluvium or colluvium derived from tuff and breccia. Annella soils are on mountain slopes. Slopes range from 2 to 60 percent. Mean annual precipitation is about 860 mm and the mean annual temperature is about 1.1 degrees C.
TAXONOMIC CLASS: Loamy-skeletal, isotic Vitrandic Dystrocryepts
TYPICAL PEDON: Annella cobbly loam, on a north-facing, 15 percent slope in coniferous forest at an elevation of 3,440 meters. (Colors are for dry soil unless otherwise noted.) When described on July 10, 1984 the soil was moist throughout. Texture and pH are from NSSL data.
Oe--0 to 10 cm; intermediately decomposed spruce needles and twigs; moderately acid (pH 5.7). (0 to 15 cm thick)
E--10 to 35 cm; light brown (7.5YR 6/4) cobbly ashy loam, brown (7.5YR 4/4), moist; weak very fine granular structure; very friable, soft, slightly sticky, slightly plastic; few coarse roots; 10 percent gravel, 20 percent cobbles, 1 percent stones; very strongly acid (pH 4.6); abrupt wavy boundary. (13 to 46 cm thick)
Bs1--35 to 56 cm; brown (7.5YR 5/4) very cobbly ashy sandy loam, dark brown (7.5YR 3/4), moist; weak fine granular structure; very friable, soft, nonsticky, nonplastic; few coarse roots; 30 percent gravel, 20 percent cobbles, 2 percent stones; very strongly acid (pH 4.5); clear wavy boundary.
Bs2--56 to 79 cm; reddish yellow (7.5YR 6/6) very cobbly ashy sandy loam, strong brown (7.5YR 4/6), moist; weak fine granular structure; very friable, soft, nonsticky, nonplastic; 30 percent gravel, 20 percent cobbles, 3 percent stones; very strongly acid (pH 4.9); clear wavy boundary. (combined thickness of the Bw horizons is 25 to 100 cm)
C1--79 to 112 cm; brownish yellow (10YR 6/6) very cobbly sandy loam, yellowish brown (10YR 5/6), moist; massive; friable, soft, nonsticky, nonplastic; 30 percent gravel, 20 percent cobbles, 3 percent stones; strongly acid (pH 5.3); gradual wavy boundary.
C2--112 to 160 cm; yellow (10YR 7/6) very cobbly sandy loam, yellowish brown (10YR 5/8), moist; massive; friable, soft, nonsticky, nonplastic; 30 percent gravel, 20 percent cobbles, 3 percent stones; strongly acid (pH 5.3).
TYPE LOCATION: Rio Grande County, Colorado; about 1 kilometer east of Summitville; in Sec. 29, T. 37 N., R. 4 E.; Summitville USGS quad; approximate lat. 37 degrees 25 minutes 30 seconds N. and long. 106 degrees 34 minutes 15 seconds W., NAD 27.
RANGE IN CHARACTERISTICS: (depths given are measured from the mineral surface)
Mean annual soil temperature: 1.1 to 3.3 degrees C.
Mean summer soil temperature: 4.4 to 7.2 degrees C.
Depth to cambic horizon: 13 to 46 cm
Thickness of the cambic horizon: 25 to 100 cm
Particle-size control section (weighted averages):
Clay content: 18 to 24 percent
Rock fragment content: 40 to 55 percent
E horizon
Hue: 7.5YR or 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3 or 4, dry or moist
Clay content: 10 to 25 percent
Rock fragments: 15 to 35 percent
Acid oxalate extractable Al + 1/2 Fe: 0.30 to 0.70 percent
Glass content: 5 to 25 percent
Base saturation: 5 to 30 percent
Reaction (pH): 4.5 to 6.0
Bs (or Bw) horizon(s)
Hue: 7.5YR or 10YR
Value: 5 to 7 dry, 3 to 6 moist
Chroma: 4 to 6, dry or moist
Texture: very gravelly ashy sandy loam, very cobbly ashy sandy loam
Clay content: 8 to 18 percent
Rock fragments: 35 to 60 percent
Acid oxalate extractable Al + 1/2 Fe: 0.50 to 1.00 percent
Glass content: 5 to 25 percent
Base saturation: 5 to 30 percent
Reaction (pH): 4.5 to 5.5
C horizon(s)
Hue: 7.5YR or 10YR
Value: 5 to 7 dry, 4 to 6 moist
Chroma: 6 to 8, dry or moist
Texture: very cobbly sandy loam, very cobbly ashy coarse sandy loam, very gravelly ashy sandy loam
Clay content: 7 to 15 percent
Rock fragments: 35 to 60 percent
Acid oxalate extractable Al + 1/2 Fe: 0.50 to 0.90 percent
Glass content: 3 to 25 percent
Base saturation: 10 to 40 percent
Reaction (pH): 4.5 to 6.0
COMPETING SERIES: None listed.
GEOGRAPHIC SETTING:
Landform - mountain slopes
Elevation - 3,048 to 3,597 meters
Slopes - 2 to 60 percent
Parent material - slope alluvium or colluvium derived from tuff and breccia
Mean annual temperature - 0.0 to 3.3 degrees C.
Mean annual precipitation - 750 to 1000 mm
Precipitation pattern - evenly distributed with heavy snowpack lasting into July and copious late summer rains from convective storms.
Frost-free period - 40 to 60 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained, medium runoff, moderate permeability.
USE AND VEGETATION: Used mainly for forestland. Potential natural vegetation is subalpine fir, Engelmann's spruce, myrtle whortleberry, heartleaf arnica, common juniper, sidebells pyrola, strawberry, and fleabane.
DISTRIBUTION AND EXTENT: Southwestern Colorado, San Juan Mountains; LRR E, MLRA 48A; small extent.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Rio Grande County, Rio Grande National Forest, West Part soil survey area, 2008. This series was drafted for use in the adjoining Archuleta and Piedra soil survey areas, using the modal pedon for the Leighcan series from the Rio Grande National Forest Area. This pedon no longer fits the Leighcan series because of its parent material lithology and its content of volcanic glass and oxalate Fe and Al content (Vitrandic feature); these Vitrandic features were not known until recently. The name is taken from a small lake a few miles from the type location in Conejos County.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Cambic horizon: 35 to 79 cm (Bs1, Bs2 horizons)
Vitrandic feature: 35 to 79 cm (Bs1 and Bs2 horizons)
Particle-size control section: 35 to 110 cm (Bs1, Bs2, and part of C1 horizon)
The cambic horizon does not qualify for a spodic horizon because it does not have twice the amount of acid oxalate Al+1/2Fe or twice the ODOE as the E horizon.
Annella soils have a cryic soil temperature regime and are in a udic soil moisture regime with a typic subclass.
ADDITIONAL DATA: NSSL sample S84CO105-004 (sampled as Leighcan).
National Cooperative Soil Survey
U.S.A.