LOCATION HOOPER CO+WY
Established Series
Rev. AJC/THB/SJJ
08/2016
HOOPER SERIES
The Hooper series consists of very deep, well drained or moderately well drained soils that formed in alluvium derived from igneous and metamorphic rock. Hooper soils are on flood plains, alluvial fans, alluvial flats, shrub-coppice dunes, and deflation basins. Slopes range from 0 to 4 percent. The mean annual precipitation is about 7 inches and the mean annual temperature is about 42 degrees F.
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive, frigid Typic Natrargids
TYPICAL PEDON: Hooper sandy loam - grassland. (Colors are for dry soil unless otherwise noted.)
E--0 to 5 inches; light gray (10YR 7/1) sandy loam, grayish brown (10YR 5/2) moist; moderate thin platy structure parting to moderate very fine granular; slightly hard, very friable; nonsticky and nonplastic; weakly calcareous; very strongly alkaline (pH 9.6); abrupt smooth boundary. (0 to 8 inches thick)
Btn--5 to 15 inches; brown (7.5YR 5/3) clay, brown (7.5YR 4/3) moist; strong medium columnar structure parting to strong fine angular blocky; slightly hard, friable, very sticky, very plastic; peds are extremely hard; moderate continuous wax-like coatings and fillings in root channels and pores; very weak gray coatings on faces of some peds; many dark magnetic mineral grains; calcareous; very strongly alkaline (pH 10.0); gradual smooth boundary. (8 to 20 inches thick)
Btnz --15 to 18 inches; light brownish gray (2.5Y 6/2) clay loam, grayish brown (2.5Y 5/2) moist; weak medium and coarse subangular blocky structure; hard, firm, moderately sticky, moderately plastic; peds are extremely hard; few thin wax-like patches on faces of peds; discontinuous wax-like coatings in root channels; many dark magnetic mineral grains; visible secondary salt accumulation as crystals and in thin seams and streaks; calcareous; very strongly alkaline (pH 10.0); gradual smooth boundary. (4 to 8 inches thick)
Bnz --18 to 32 inches; light brownish gray (2.5Y 6/2) sandy clay loam, grayish brown (2.5Y 5/2) moist; massive; hard, friable, nonsticky, slightly plastic; many dark magnetic mineral grains; visible secondary salts occurring as crystals and in thin seams and streaks; few dark flecks; calcareous; very strongly alkaline (pH 10.0); clear smooth boundary. (0 to 25 inches thick)
2C--32 to 60 inches; grayish brown (2.5Y 5/2) sand, dark grayish brown (2.5Y 4/2) moist; single-grained; loose; a large amount of dark gray and red volcanic minerals grains; calcareous; very strongly alkaline (pH 10.0). (Several feet thick)
TYPE LOCATION: Alamosa County, Colorado; about 8 miles northwest of Alamosa; 150 feet east and 20 feet south of the W1/4 corner of Sec. 21, T. 38 N., R. 9 E.; lat. 37 degrees 31 minutes 25 seconds N. and long. 106 degrees 00 minutes 09 seconds W., WGS 84.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature: 41 to 47 degrees F (5.0 to 7.4 degrees C)
Mean summer soil temperature: 59 to 63 degrees F (15.0 to 17.2 degrees C)
Depth to free carbonates: 0 to 24 inches (0 to 61 centimeters) but it does not extend more than 3 inches into the Btn horizon
Depth to base of the natric horizon: 10 to 40 inches (25 to 102 centimeters)
Depth to secondary carbonates, gypsum, or more soluble salts: 10 to 40 inches (25 to 102 centimeters)
Depth to the coarse textured 2C horizon: 20 to 40 inches (51 to 102 centimeters)
Seasonal high water table: may be within 4 feet (1.2 meters) of the surface but normally is below 6 feet (1.8 meters) See Remarks section; this will likely be revised to below 150cm only.
Particle-size control section (weighted average):
Upper part:
Noncarbonate clay content: 18 to 26 percent
Rock fragment content: 0 to 15 percent
Sand content, fine sand and coarser: 15 to 35 percent
Lower part:
Noncarbonate clay content: 0 to 5 percent
Rock fragment content: 0 to 45 percent
E horizon (A horizon in some pedons):
Hue: 7.5YR through 5Y
Value: 5 to 7 dry; 3 to 6 moist
Chroma: 1 to 4
Texture: sandy loam, loamy sand, loamy fine sand, and clay loam
Clay content: 5 to 39 percent
Exchangeable sodium percentage: less than 15 percent
Reaction: moderately alkaline to very strongly alkaline
Btn and Btnz horizons (Btkn in some pedons):
Hue: 7.5YR through 5Y
Value: 5 to 6 dry; 3 to 5 moist
Chroma: 2 through 4
Texture: clay, clay loam, sandy clay loam
Clay content: 20 to 50 percent
Gravel content: 0 to 10 percent
Exchangeable sodium percentage: 15 to 60 percent in a majority of subhorizons
Reaction: strongly alkaline or very strongly alkaline
Bnz horizon (Bkn in some pedons):
Hue: 7.5YR through 5Y
Value: 5 to 6 dry; 3 to 5 moist
Chroma: 2 through 4
Texture: sandy clay loam, sandy loam, gravelly clay loam
Clay content: 10 to 40 percent
Gravel content: 0 to 20 percent
C horizon (present in some pedons above 40 inches (102 centimeters)):
Clay content: 15 to 35 percent
2C horizon:
Hue: 7.5YR through 5Y
Value: 5 to 7 dry; 4 to 6 moist
Chroma: 2 through 4
Texture: sand, coarse sand, loamy sand, gravelly sand, very gravelly sand
Clay content: 0 to 5 percent
Gravel content: 0 to 45 percent
Cobble content: 0 to 5 percent
Reaction: strongly alkaline or very strongly alkaline
COMPETING SERIES: There are currently no known series in this family. Closely related soils are the
Mosca and
Goshute series. Mosca soils have a coarse-loamy control section. Goshute soils do not have visible salt crystals in the upper solum and have a mesic temperature regime.
GEOGRAPHIC SETTING:
Parent material: alluvial materials derived from mixed sources (igneous and metamorphic rock). Commonly rhyolite, andesite, basalt, gneiss, and schist.
Landform: Flood plains, alluvial fans, alluvial flats, shrub-coppice dunes, and deflation basins with slopes of 0 to 4 percent.
Mean annual precipitation: 6 to 9 inches (152 to 229 millimeters)
Mean annual air temperature: 39 to 46 degrees F (4.0 to 7.8 degrees C)
Elevation ranges from 6,500 to 8,000 feet (1,980 to 2440 meters), and the Frost Free Period ranges from 85 to 100 days.
Precipitation pattern: Precipitation peaks in July and August occurring mostly as intense summer thunderstorms.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
San Luis,
Cososa, and
Mosca soils.
Mosca soils do not have visible salts in the solum.
San Luis soils are somewhat poorly drained.
Cososa soils do not have natric horizons.
DRAINAGE AND PERMEABILITY: Well drained or moderately well drained; low runoff; slow to very slow permeability.
USE AND VEGETATION: These soils are used principally as native pastureland. Principal native vegetation includes thin stands of greasewood with some rabbitbrush. Occasionally, there is scattered alkali sacaton and saltgrass.
DISTRIBUTION AND EXTENT: San Luis Valley Area of south-central Colorado, LRR E, MLRA 51. Also some small areas in LRR D, MLRA 34 in Wyoming. The series is of large extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Rio Grande County, Colorado, 1972; proposed in 1945. The typical pedon is in the Alamosa Area, Colorado, but it is not the modal pedon in that area.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Particle-size control section: from 5 to 40 inches (Btn, Btnz, Bnz, and upper part of 2C horizon)
Ochric epipedon and albic horizon: from 0 to 5 inches (E horizon)
Natric horizon: from 5 to 32 inches (Btn and Btnz horizons)
Strongly contrasting particle-size class: at 32 inches. The sandy clay loam Bnz is assumed to have less than 50 percent fine sand and coarser sand; the weighted average noncarbonate clay in the upper part of the PSCS is assumed greater than 18 percent.
The 09/2008 revison changed the particle-size family from clayey over sandy or sandy-skeletal to fine-loamy over sandy or sandy skeletal, with the accompanying change of the mineralogy class from smectitic to mixed.
The parent material is more accurately defined as being derived from mixed sources (igneous and metamorphic rock); the original concept was being derived from volcanic rock, jwb, 4/2009
This series has historically beeen recognized with a highly variable depth to water table- within 4 feet to greater than 6 feet. The 12/2011 revision provisionally retains the original water table criterion, but it is likely the central concept of this series will be revised to have no saturation within the series control section (150 cm). Drainage class would then be well drained only. More field investigation will be required before this change can definitely be made.
Taxonomy version: Eleventh Edition, 2010
National Cooperative Soil Survey
U.S.A.