LOCATION EDCO TX

Established Series
Rev. JKW-RM
01/2018

EDCO SERIES

The Edco series consists of very deep, somewhat poorly drained, very slowly permeable soils that formed in thick loamy fluviomarine deposits of the Lissie Formation. These soils are on flats on coastal prairies. Slope ranges from 0 to 1 percent. Mean annual temperature is about 21 degrees C (70 degrees F) and mean annual precipitation is about 1116 mm (44 in).

TAXONOMIC CLASS: Fine, mixed, active, hyperthermic Oxyaquic Vertic Hapludalfs

TYPICAL PEDON: Edco fine sandy loam--rice field. (Colors are for moist soil unless otherwise stated.)

Ap1--0 to 10 cm (0 to 4 in); dark grayish brown (10YR 4/2) fine sandy loam, pale brown (10YR 6/3) dry; weak medium subangular blocky structure; soft, friable, slightly sticky and slightly plastic; many fine roots; 1 percent siliceous pebbles; common fine pores; many fine and medium faint dark gray (10YR 4/1) iron depletions with diffuse boundaries on surfaces of peds; common fine faint dark yellowish brown rhizospheres; moderately acid; clear wavy boundary. (10 to 30 cm [4 to 12 in] thick)

Ap2--10 to 18 cm (4 to 7 in); dark gray (10YR 4/1) fine sandy loam, light brownish gray (10YR 6/2) dry; weak medium subangular blocky structure parting to weak fine subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; few fine masses of iron-manganese; 1 percent siliceous pebbles; many fine faint dark yellowish brown (10YR 4/4) masses of iron accumulation with clear boundaries of surfaces of peds; neutral; abrupt wavy boundary. (0 to 20 cm [0 to 8 in)] thick)

Bt1--18 to 36 cm (7 to 14 in); dark grayish brown (10YR 4/2) clay, grayish brown (10YR 5/2) dry; strong fine and medium angular blocky structure; very hard, extremely firm, very sticky and very plastic; common fine roots; few distinct pressure faces and wedged-shaped aggregates; few vertical cracks 5 to 10 mm wide partly filled with material from above; many distinct clay films on surfaces of peds; 1 percent siliceous pebbles; few fine faint dark yellowish brown, few fine distinct strong brown (7.5YR 5/6) and common medium and coarse distinct yellowish brown (10YR 5/6) masses of iron accumulation with sharp boundaries on surfaces of peds; neutral; clear smooth boundary.

Bt2--36 to 79 cm (14 to 31 in) grayish brown (2.5Y 5/2) sandy clay, light brownish gray (2.5Y 6/2) dry; moderate fine and medium angular blocky structure; very hard, extremely firm, very sticky and very plastic; common fine roots; few distinct pressure faces and wedged-shaped aggregates; few vertical cracks 5 to 10 mm wide partly filled with material from above; many distinct clay films on surfaces of peds; 1 percent siliceous pebbles; few fine distinct yellowish brown (10YR 5/6) and many medium and coarse faint light olive brown (2.5Y 5/4) masses of iron accumulation with clear and sharp boundaries on surfaces of peds; common medium and coarse dark grayish brown (10YR 4/2) iron depletions with diffuse boundaries on surfaces of peds; neutral; clear smooth boundary.

Bt3--79 to 112 cm (31 to 44 in); grayish brown (2.5Y 5/2) sandy clay loam, light brownish gray (2.5Y 6/2) dry; moderate medium angular blocky structure; very hard, extremely firm, very sticky and very plastic; many distinct clay films on surfaces of peds; few fine concretions of iron-manganese; 2 percent siliceous pebbles; common medium faint light olive brown (2.5Y 5/4) masses of iron accumulation with clear boundaries; neutral; clear smooth boundary. (Combined thickness of the Bt horizons is 38 to 127 cm [15 to 50 in])

Btk--112 to 142 cm (44 to 56 in); light brownish gray (2.5Y 6/2) sandy clay loam, light gray (2.5Y 7/2) dry; strong coarse subangular blocky structure; very hard, extremely firm, very sticky and very plastic; common distinct clay films on surfaces of peds; few fine concretions of iron-manganese; common fine to coarse concretions of calcium carbonate; 2 percent siliceous pebbles; few fine distinct brown (10YR 5/3), strong brown (7.5YR 5/6) and common medium distinct light yellowish brown (2.5Y6/4) masses of iron accumulation with clear and sharp boundaries on surfaces of peds; violently effervescent; moderately alkaline; clear smooth boundary. (0 to 38 cm [0 to 15 in] thick)

BCtk--142 to 173 cm (56 to 68 in); light gray (10YR 7/2) sandy clay loam, light gray (2.5Y 7/2) dry; moderate medium subangular blocky structure; very hard, extremely firm, very sticky and very plastic; few faint clay films on surfaces of peds; few fine rounded concretions of iron-manganese; common fine to coarse rounded concretions of calcium carbonate; common fine and medium soft flakes and threads of manganese; 2 percent rounded siliceous pebbles; few fine and medium distinct yellowish brown (10YR 5/6) and many fine distinct brownish yellow (10YR 6/6) and yellow (10YR 7/6) masses of iron accumulation with sharp boundaries on surfaces of peds; violently effervescent; moderately alkaline; clear smooth boundary. (0 to 51 cm [0 to 20 in] thick)

BCk1--173 to 188 cm (68 to 74 in); light gray (10YR 7/1) sandy clay loam, light gray (2.5Y 7/2) dry; moderate medium subangular blocky structure; very hard, extremely firm, very sticky and very plastic; few fine threads of iron-manganese; common fine and medium concretions of calcium carbonate; common fine and medium crystals and concretions of barite; 3 percent siliceous pebbles; common fine distinct brownish yellow (10YR 6/6) and common fine and medium distinct strong brown (7.5YR 5/6) masses of iron accumulation with sharp boundaries on surfaces of peds; violently effervescent; moderately alkaline; clear smooth boundary. [0 to 51 cm (0 to 20 in) thick]

BCk2--188 to 203 cm (74 to 80 in); light gray (10YR 7/1) sandy clay loam, light gray (2.5Y 7/2) dry; weak medium subangular blocky structure; very hard, extremely firm, very sticky and very plastic; few fine masses of iron-manganese; common fine and medium concretions of calcium carbonate; many fine and medium crystals and concretions of barite; 3 percent siliceous pebbles; common fine and medium prominent yellowish red (5YR 5/8) and many fine and medium distinct brownish yellow (10YR 6/6) masses of iron accumulation with sharp boundaries on surfaces of peds; violently effervescent; moderately alkaline.

TYPE LOCATION: Colorado County, Texas, in Eagle Lake, from the intersection of U.S. Highway Alternate 90 and Farm Road 3013, 4.0 miles south on Farm Road 3013, 0.6 mile east on field road and 300 ft south in rice field.
USGS topographic quadrangle: Eagle Lake;
Latitude: 29 degrees, 31 minutes, 43.5 seconds N;
Longitude: 96 degrees, 18 minutes, 48.5 seconds W;
Datum: WGS 84.

RANGE IN CHARACTERISTICS:
Soil Moisture: Udic soil moisture regime. The soil moisture control section is moist in some or all parts for more than 275 days in normal years.

Mean annual soil temperature: 21.7 to 22.2 degrees C (71 to 72 degrees F)
Combined thickness of the A horizons: 10 to 30 cm (4 to 12 in)

Ap horizon
Hue: 10YR
Value: 4 or 5
Chroma: 1 to 3
Texture: fine sandy loam and loam
Clay content: 6 to 22 percent
Rock fragments: amount-0 to 3 percent; kind-silica
Redox concentration: amount-none to common, shades-red, yellow, brown
Redox depletions: amount: none to common; shades-gray
Electrical conductivity (decisiemens per meter): 0 to 2
Sodium adsorption ratio: 0 to 12
Reaction: strongly acid to neutral

Bt horizon
(Upper part)
Hue: 10YR or 2.5Y
Value: 4 to 7
Chroma: 1 or 2
Texture: clay loam, sandy clay or clay
Clay content: 32 to 55 percent
Rock fragments: amount-0 to 5 percent; kind-silica
Redox concentration: amount-few to common, shades-red, yellow, brown or olive
Redox depletions: amount: none to common; shades-gray
Identifiable secondary carbonates: amount-0 to 5 percent
Electrical conductivity (decisiemens per meter): 0 to 2
Sodium adsorption ratio: 1 to 12
Reaction: strongly acid to neutral

Bt horizon
(Lower part)
Hue: 10YR or 2.5Y
Value: 4 to 7
Chroma: 1 or 2
Texture: sandy clay loam, clay loam, sandy clay or clay
Clay content: 25 to 45 percent
Rock fragments: amount-0 to 5 percent; kind-silica
Redox concentration: amount-few to common, shades-red, yellow, brown or olive
Redox depletions: amount: none to common; shades-gray
Identifiable secondary carbonates: amount-0 to 5 percent
Electrical conductivity (mmhos/cm): 0 to 3
Sodium adsorption ratio: 6 to 17
Reaction: slightly acid to slightly alkaline

Btk, BCtk and BCk horizons
Hue: 10YR to 2.5Y
Value: 4 to 7
Chroma: 1 or 2
Texture: sandy clay loam, clay loam, sandy clay, or clay
Clay content: 27 to 45 percent
Rock fragments: amount-0 to 5 percent; kind-silica
Redox concentrations: amount-common or many; shades-red, yellow, brown or olive
Identifiable secondary carbonates: kind-concretions, masses, films and threads; amount-few to many
Electrical conductivity (decisiemens per meter): 0 to 4
Sodium adsorption ratio: 5 to 28
Reaction: neutral to moderately alkaline

Solum thickness ranges from 152 to more than 203 cm (60 to more than 80 in). The upper part of the argillic horizon cracks when dry. When dry, the Ap horizon is massive and very hard or extremely hard.

COMPETING SERIES: This is the Nez series in the same family. Similar soils are the Edna, Katy, Levac, Telferner, Telf, Yeaton, and the Tidehaven series.
Nez, Telf and Telferner soils: ochric epipedon from 25 to 51 cm (10 to 20 in) thick; in addition Telferner soils have smectitic mineralogy.
Edna soils: smectitic mineralogy; formed in loamy fluviomarine sediments of the Beaumont Formation.
Katy soils: fine-loamy family; an ochric epipedon 46 to 76 cm (18 to 30 in) thick.
Levac and Yeaton soils: smectitic mineralogy; in areas of higher rainfall
Tidehaven soils: smectitic mineralogy; have reddish colors in the lower part of the argillic horizon

GEOGRAPHIC SETTING:
Parent material: loamy fluviomarine deposits of early Pleistocene age
Landscape: coastal plains
Landform: flats
Slope: 0 to 1 percent
Mean annual precipitation: 1016 to 1219 mm (40 to 48 in)
Thornthwaite P-E Index: 52 to 62
Mean annual air temperature: 20.0 to 21.0 degrees C (68 to 70 degrees F)
Frost-free period: 271 to 300 days
Elevation: 37 to 55 m (120 to 180 ft)

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cieno, Katy, Nada, Nez, and Telf series.
Cieno soils: are in the fine-loamy family, have an aquic moisture regime and are in slightly lower oval depressions.
Katy, Nez, and Telf soils: are in similar landscape positions.
Nada soils: are in the fine-loamy family and are on similar landscape positions.

DRAINAGE AND PERMEABILITY:
Drainage class: somewhat poorly drained
Permeability: very slow.
Runoff: high on 0 to 1 percent slopes
Seasonal water table: water perches on top of the argillic horizon for a periods of about 2 to 4 weeks cumulative from January to April in normal years.

USE AND VEGETATION: Mainly used for rice production. Some areas are in native pasture. Native grasses are mainly prairie grasses of species of Andropogon, Paspalum, Panicum, and Sporobolus.

DISTRIBUTION AND EXTENT:
General area: Coastal Prairie of Texas
Land Resource Region: T (Atlantic and Gulf Coast Lowland Forest and Crop Region)
Major Land Resource Area: 150A (Gulf Coast Prairies)
Extent: moderate

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Temple, Texas.

SERIES ESTABLISHED: Colorado County, Texas; 1997.

REMARKS: These soils were formerly included in the Edna series. This soil does not have an aquic moisture regime. The classification was changed from Aquertic Chromic Hapludalfs to Oxyaquic Vertic Hapludalfs in 2016 during the update of MLRA 150A. The Aquertic Chromic classification was based on preliminary analysis of a soil moisture study on a similar soil on a similar landform. Upon further analysis, the previously noted aquic conditions occurred during abnormally wet years. During normal years, these soils will become saturated in the zone above the argillic horizon but not long enough for reduction to take place. The series classification supports mixed mineralogy and is based on reference samples analyzed for mineralogy by Texas A&M University.

Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon: 0 to 18 cm (0 to 7 in) (Ap and A horizons)

Argillic horizon: 18 to 173 cm (7 to 68 in) (Bt1, Bt2, Bt3, Btk and BCtk horizons)

Vertic feature: Cracks and/or wedge-shaped aggregates within the upper part of the argillic horizon.

Secondary carbonates: 112 to 203 cm (44 to 80 in) (Btk, BCtk, BCk1, and BCk2 horizons)

ADDITIONAL DATA: S97TX-089-13-2, Texas A&M University.

Taxonomic Version: Keys to Soil Taxonomy, Twelfth Edition, 2014.

National Cooperative Soil Survey
U.S.A.