LOCATION IMOGENE TX

Established Series
WJG-JKW-GWH
11/2010

IMOGENE SERIES

The Imogene series consists of very deep, moderately well drained soils that formed in saline, calcareous, loamy sediments of Pliestocene or Recent age. These nearly level to very gently sloping soils are on low stream terraces. Slope ranges from 0 to 2 percent. Mean annual precipitation is about 711 mm (28 in) and the mean annual air temperature is about 21.5 degrees C (70.5 degrees F).

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, hyperthermic Mollic Natrustalfs

TYPICAL PEDON: Imogene fine sandy loam, on northwest-facing, plane, .5 percent slope in rangeland; elevation is 76 meters (251 feet). (Colors are for dry soil unless otherwise stated.)

A--0 to 13 cm (0 to 5 in); grayish brown (10YR 5/2) fine sandy loam, very dark grayish brown (10YR 3/2) moist; massive; hard, friable; common fine roots; slightly acid; abrupt smooth boundary. (8 to 30 cm [3 to 12 in] thick)

Btn--13 to 30 cm (5 to 12 in); dark grayish brown (10YR 4/2) sandy clay loam, very dark grayish brown (10YR 3/2) moist; moderate coarse columnar structure parting to moderate fine and medium subangular blocky; hard, friable; common fine roots; prominent clay films on vertical surfaces of peds; few fine masses of calcium carbonate; slightly alkaline; clear wavy boundary. (10 to 30 cm [4 to 12 in] thick)

Btkn--30 to 71 cm (12 to 28 in); grayish brown (10YR 5/2) sandy clay loam, dark grayish brown (10YR 4/2) moist; moderate coarse columnar structure parting to moderate fine and medium subangular blocky; hard, friable; common fine roots; distinct clay films on vertical surfaces of peds; common fine masses of calcium carbonate; slightly effervescent; moderately alkaline; gradual wavy boundary. (15 to 56 cm [6 to 22 in] thick)

Bnz--71 to 122 cm (28 to 48 in); light gray (2.5Y 7/2) sandy clay loam, light brownish gray (2.5Y 6/2) moist; weak fine subangular blocky structure; hard, friable; few fine masses of calcium carbonate; few threads of other neutral salts; few fine yellowish brown streaks; slightly effervescent; moderately alkaline; gradual wavy boundary. (25 to 76 cm [10 to 30 in] thick)

BCnz--122 to 203 cm (48 to 80 in); light gray (2.5Y 7/2) sandy clay loam, light brownish gray (2.5Y 6/2) moist; weak medium subangular blocky structure; very hard, friable; few fine masses of calcium carbonate; few threads of other neutral salts; few fragments of shale; few fine yellowish brown streaks; slightly effervescent; moderately alkaline.

TYPE LOCATION: Atascosa County, Texas; 6.6 miles southwest of Campbellton on Farm Road 791; 0.6 mile south to 7-4 Ranch Headquarters; about 0.6 mile southeast of headquarters in rangeland. Whitsett, Texas USGS topographic quadrangle: Latitude: 28 degrees 40 minutes 05.4 seconds N; Longitude: 98 degrees 22 minutes 0.3 seconds W.; NAD 83.

RANGE IN CHARACTERISTICS:

Soil Moisture: Soil Moisture: A typic-ustic moisture regime. The soil moisture control section is dry in some or all parts for more than 90 days but less than 180 cumulative days in normal years. June through August and December through February are the driest months. These soils are intermittently moist in September through November and March through May.
Mean annual soil temperature:22 to 23.5 (72 to 74 degrees F).
Particle-size control section (weighted average)
Clay content: 20 to 35 percent
CEC/clay ratio: 0.6 to 0.70
Sodium absorption ratio: 13 to 40

A Horizon
Hue: 10YR
Value: 3 to 5
Chroma: 1 to 4
Texture: fine sandy loam, loam, or very fine sandy loam
Clay content: 8 to 18 percent
EC (dS/m): 0 to 4
SAR: 2 to 18
Reaction: slightly acid to slightly alkaline

Btn Horizon
Hue: 7.5YR, 10YR, or 2.5Y
Value: 3 to 5
Chroma: 1 to 4
Texture: loam, sandy clay loam, or clay loam
Clay content: 20 to 35 percent
EC (dS/m): 2 to 6
SAR: 13 to 40
Reaction: neutral to moderately alkaline

Btkn Horizon
Hue: 10YR, or 2.5Y
Value: 5 to 8
Chroma: 2 to 4
Texture: loam, sandy clay loam, clay loam, or sandy clay
Clay content: 20 to 40 percent
Calcium carbonate equivalent: 0 to 30 percent
Identifiable secondary carbonate: amount-few to many, size-, kind-masses,
threads, or nodules
EC (dS/m): 2 to 20
SAR: 25 to more than 40
Effervescence: very slight to strong
Reaction: neutral to strongly alkaline

Bnz (Bknz Horizon where present)
Hue: 10YR to 5Y
Value: 4 to 7
Chroma: 1 to 3
Texture: sandy clay loam or clay loam
Clay content: 20 to 35 percent
Calcium carbonate equivalent: 0 to 5 percent
Identifiable secondary carbonate: amount-none to common, kind-masses, threads, or
nodules
EC (dS/m): 2 to 8
SAR: 20 to 40
Effervescence: none to slight
Reaction: neutral to strongly alkaline

BCnz Horizon (BC where present)
Hue: 10YR to 2.5Y
Value: 5 to 7
Chroma: 1 to 3
Texture: sandy clay loam or clay loam
Clay content: 20 to 35 percent
Calcium carbonate equivalent: 0 to 5 percent
Identifiable secondary carbonate: amount-few to many, kind-masses, threads, or
nodules
EC (dS/m): 2 to 8
SAR: 10 to 40
Effervescence: very slight to strong
Reaction: neutral to strongly alkaline
COMPETING SERIES: There are no series in the same family. Similar soils are the
Bauman (TX), Brundage (TX), Palobia (TX), and the tentative Greta (TX) series.
Bauman soils: in a thermic soil temperature; do not have a mollic epipedon
Brundage soils: do not have a mollic epipedon; is dry in some part for
six-tenths or more of the cumulative days per year
Palobia soils: do not have a mollic epipedon; have an active CEC/clay class
Greta soils: do not have a mollic epipedon; has oxyaquic conditions for at least
30 cumulative days each year

GEOGRAPHIC SETTING:
Parent material: saline, calcareous, loamy sediments of Pliestocene or Recent
age
Landscape: inland dissected Coastal plains
Landform: low stream terraces
Slope: are mostly less than 1 percent but range to 2 percent
Mean annual air temperature range: 21 to 23.5 degrees C (70 to 74 degrees F)
Mean annual precipitation range: 610 to 813 mm (24 to 32 in)
Precipitation Pattern: November through March and July through August are the
driest months, while April through June and September through October are the
wettest.
Frost-free period: 265 to 300 days
Elevation: 61 to 213 m (200 to 700 ft)
Thornthwaite annual P-E indices: 28 to 44

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Brundage (TX), Miguel (TX),
Orelia (TX), Campellton (TX), Coy (TX), and the Laparita (TX) series.
Brundage soils: on a similar to slightly higher landform
Miguel soils: have a clayey argillic horizon; are on a hillslope landform
Orelia soils: are on flat coastal plains; do not have a natric horizon
Cambellton, Coy and Laparita soils: have a clayey argillic horizon; are on
hillslope landform

DRAINAGE AND PERMEABILITY: Moderately well drained. Permeability is very slow.
Runoff is low on 0 to 1 percent slopes and medium on 1 to 2 percent slopes.

USE AND VEGETATION: Used almost exclusively as rangeland. Native vegetation
includes grasses such as hooded windmillgrass, bristlegrass, lovegrass,
grassburr, sand dropseed, Hall panicum, threeawn, and red grama. Woody plants
include mesquite, spiny hackberry, white brush, wolfberry, guayacan, condalias,
vine ephedra, agarita, and yucca. Ecological site is Tight Sandy Loam 25-35"
PZ; (R083AY412TX).

DISTRIBUTION AND EXTENT: The Northern Rio Grande Plain, Texas; LRR I; MLRA 83A; moderate extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: Atascosa County, Texas; 1977.

REMARKS:

Diagnostic horizon and features recognized in this pedon are:
Ochric epipedon--0 to 13 cm (0 to 5 in) (A horizon)
Mollic subgroup--The surface has mollic colors but is both massive and hard when
dry and will not qualify for the Mollisol order.
Natric horizon--13 to 71 (5 to 28 in) (Btn and Btkn horizons)

ADDITIONAL DATA: Lab data available on pedons from Goliad, Karnes, and Gonzales
counties from local lab.

TAXONOMIC VERSION: Keys to Soil Taxonomy, Eleventh Edition, 2010

National Cooperative Soil Survey
U.S.A.