LOCATION CONROE TX
Established Series
Rev. CDB-JMG-HLH
04/2022
CONROE SERIES
The Conroe series consists of deep, moderately well drained, slowly permeable soils that formed in acid clayey and loamy fluviomarine deposits of the Willis Formation. These soils occur on summits of interfluves of inland dissected coastal plains. The slope range is 0 to 12 percent. Mean annual precipitation is about 1245 mm (49 in) and mean annual air temperature is about 19.4 degrees C (63 degrees F).
TAXONOMIC CLASS: Clayey, kaolinitic, thermic Arenic Plinthic Paleudults
TYPICAL PEDON: Conroe gravelly loamy fine sand--forested. (Colors are for moist soil unless otherwise stated.)
A--0 to 10 cm (0 to 4 in); grayish brown (10YR 5/2) gravelly loamy fine sand, light gray (10YR 7/2) dry; single grained; loose; very friable; many medium and coarse roots; 17 percent by volume of nodules of ironstone up to 2 cm in diameter; very strongly acid; clear smooth boundary. (Thickness is 8 to 20 cm [3 to 8 in])
E--10 to 64 cm (4 to 25 in); light yellowish brown (10YR 6/4) gravelly loamy fine sand, very pale brown (10YR 7/4) dry; single grained; loose; many medium and coarse roots; 43 percent by volume of nodules of ironstone up to 2 cm in diameter; strongly acid; gradual wavy boundary. (Thickness is 38 to 64 cm [15 to 25 in])
Bt--64 to 79 cm (25 to 31 in); yellowish brown (10YR 5/6) sandy clay loam; brownish yellow (10YR 6/6) dry; common fine and medium distinct yellowish red and red mottles; moderate fine blocky structure; slightly firm, hard; common medium and coarse roots; few fine pores; thin patchy clay films on some peds; the centers of some mottles are slightly cemented dark red concretions; 20 percent by volume of nodules of ironstone; very strongly acid; gradual wavy boundary. (Thickness is 8 to 41 cm [3 to 16 in])
Btv1--79 to 97 cm (31 to 38 in); yellowish brown (10YR 5/6) sandy clay; many coarse and medium prominent red mottles; moderate medium blocky structure; extremely hard, firm and brittle, slightly sticky; few medium and coarse roots in the yellowish brown areas; few fine pores; thick continuous clay films; 10 percent by volume nodules of ironstone; plinthite comprises about 30 percent of the horizon and some red mottles have weakly cemented red concretions in their centers; very strongly acid; gradual wavy boundary. (Thickness is 13 to 36 cm (5 to 14 in))
Btv2--97 to 173 cm (38 to 68 in); coarsely and prominently mottled red (2.5YR 4/8) and red (10R 4/8) and yellow (10YR 7/6) dry, sandy clay; common coarse light brownish gray (10YR 6/2) mottles on the outsides of some peds; many of the coarse red mottles are bridged together; moderate coarse blocky structure, parting to fine and medium blocky structure; extremely hard, firm and brittle, slightly sticky; few roots penetrate parts of the yellow and light brownish gray areas and are concentrated in the uncemented part; few fine pores; few brown stains on faces of peds; thick continuous clay films; 6 percent by volume nodules of ironstone; about 40 percent plinthite; very strongly acid; diffuse wavy boundary. (Thickness is 38 to 89 cm [15 to 35 in])
Btv3--173 to 198 cm (68 to 78 in); coarsely and prominently mottled reddish yellow (7.5YR 6/8) and red (10R 4/8) dry, sandy clay; common medium light gray (10YR 7/1) streaks; moderate coarse blocky structure and few weak horizontal stratifications; extremely hard, brittle, firm; few fine roots in the gray areas; few fine pores; some coarse prisms have thick continuous glossy clay coatings; about 40 percent coarse red mottles of plinthite; few nodules of ironstone up to about 1 cm in diameter; common bridging of coarse red mottles; strongly acid; gradual wavy boundary. (Thickness is 25 to 64 cm [10 to 25 in])
BCv--198 to 244 cm (78 to 96 in); coarsely and distinctly mottled weak red (10R 5/4), red (2.5YR 4/8; 10R 4/8) and pale brown (10YR 7/4) dry, sandy clay loam; weak very coarse blocky structure and common weak horizontal stratifications; extremely hard, firm, brittle; few fine roots; few medium and coarse pores filled with yellowish brown clay; few of the red mottles are weakly cemented; 30 to 40 percent plinthite; clay plugs fills channels that are at various angles from the horizontal plane, they are mostly less than 5 cm in diameter and extend less than 6 inches and are mostly 2 to 3 inches in length; thick patchy clay coatings up to about 2 mm thick on horizontal planes; strongly acid.
TYPE LOCATION: Montgomery County, Texas; from the intersection of U.S. Highway 75 and Farm Road 2432 in Willis, Texas; 4.4 miles southeast on Farm Road 2432; then north on private road 0.15 mile and 100 feet east of private road in woods.
USGS topographic quadrangle: Willis, TX;
Latitude: 30 degrees, 23 minutes, 37.11 seconds N;
Longitude: 95 degrees, 24 minutes, 45.24 seconds W
Decimal Degrees
Std Latitude: 30.39364
Std Longitude: -95.41257
Datum: WGS84
RANGE IN CHARACTERISTICS:
Soil Moisture: Typic Udic soil moisture regime. The soil moisture control section is not dry in any part for as long as 90 days in normal years.
Soil Depth: deep, 152 cm to more than 254 cm (60 to more than 100 in)
Thickness of ochric epipedon: 50 to 84 cm (20 to 33 in)
Depth to abrupt textural change: 50 to 84 cm (20 to 33 in)
Depth to albic horizon: 8 to 20 cm (3 to 8 in)
Depth to argillic horizon: 50 to 84 cm (20 to 33 in)
Depth to plinthite: 58 to 109 cm (23 to 43 in)
Particle-size control section (weighted average)
Clay content: 35 to 50 percent
Rock fragments: 0 to 14 percent
A Horizon
Hue: 10YR
Value: 4 to 7, dry or moist
Chroma: 1 to 3, dry or moist
Texture: loamy fine sand, loamy sand, gravelly loamy fine sand, gravelly loamy sand, very gravelly loamy fine sand, very gravelly loamy sand
Rock fragments: amount-0 to 50 percent; size-fine to medium gravel; kind-ironstone
Reaction (pH): very strongly acid to slightly acid (4.5 to 6.5)
E Horizon
Hue: 10YR
Value: 5 to 7, dry or moist
Chroma: 1 to 4, dry or moist
Texture: loamy fine sand, loamy sand, gravelly loamy fine sand, gravelly loamy sand, very gravelly loamy fine sand, very gravelly loamy sand
Rock fragments: amount-0 to 50 percent; size-fine to medium gravel; kind-ironstone
Reaction (pH): very strongly acid to slightly acid (4.5 to 6.5)
Bt Horizon
Hue: 10YR
Value: 5 to 6, dry or moist
Chroma: 4 to 8, dry or moist
Mottles: 1 to 19 percent, fine to medium, red, or yellowish red
Texture: sandy clay loam, sandy clay, clay loam, clay
Rock fragments: amount-1 to 25 percent; size-fine to medium gravel; kind-ironstone
Plinthite: 0 to 10 percent
Reaction (pH): very strongly acid to strongly acid (4.5 to 5.5)
Btv Horizon
Hue: 10YR
Value: 5 to 6, dry or moist
Chroma: 4 to 8, dry or moist
Mottles: 2 to 50 percent; fine to coarse; light gray, gray, strong brown, pale brown, yellowish brown, brownish yellow, yellow, yellowish red, red, or dark red
Texture: sandy clay, clay (with less than 20 percent silt)
Clay percentage: 35 to 50,
Rock fragments: amount-1 to 15 percent; size-fine to medium gravel; kind-ironstone
Plinthite: 10 to 50 percent
Reaction (pH): very strongly acid to strongly acid (4.5 to 5.5)
BCv Horizon (where present)
Hue: 10YR
Value: 5 to 6, dry or moist
Chroma: 4 to 8, dry or moist
Mottles: 2 to 50 percent; coarse; light gray, strong brown, pale brown, yellowish brown, red, or dark red
Texture: sandy clay loam, sandy clay
Rock fragments: amount-1 to 15 percent; size-fine to medium gravel; kind-ironstone
Plinthite: 10 to 50 percent
Reaction (pH): very strongly acid to strongly acid (4.5 to 5.5)
COMPETING SERIES: There are no competing series in the same family. Similar series are the
Depcor,
Fuquay,
Gunter,
Lilbert,
Rogan,
Sunsweet and
Wicksburg.
Depcor soils: have loamy control sections and have base saturation greater than 35 percent.
Fuquay,
Lilbert, and
Rogan soils: have loamy control sections. In addition, Rogan soils lack sandy A horizons more than 51 cm (20 in) thick.
Gunter soils: have sandy A horizons more than 102 cm (40 in) thick.
Sunsweet soils: lack sandy A horizons more than 20 inches thick.
Wicksburg soils: lack 5 percent or more plinthite in the solum.
GEOGRAPHIC SETTING:
Parent material: unconsolidated, acid, sandy clays and sands derived from fluviomarine deposits of the Willis Formation
Landscape: inland coastal dissected plains
Landform: hillslopes, interfluves
Slope: 0 to 12 percent, mainly 1 to 4 percent
Mean annual precipitation: 1016 to 1397 mm (40 to 55 in)
Thornthwaite P-E Index: greater than 64
Mean annual air temperature: 19.4 to 21.1 degrees C (67 to 70 degrees F). The climate is warm and humid.
GEOGRAPHICALLY ASSOCIATED SOILS: These are
Boy,
Depcor,
Fetzer,
Gunter,
Lilbert,
Rogan,
Segno,
Splendora, and
Woodville series.
Boy soils: have loamy control sections, base saturation greater than 35 percent, have grossarenic subgroup, occur on similar positions, have aquic conditions.
Depcor,
Lilbert, and
Rogan soils: are on slightly lower gentle slopes.
Fetzer soils: have fine-loamy control sections, base saturation greater than 35 percent, occur on lower concave footslopes, have aquic conditions
Gunter soils: are on similar positions.
Segno and
Woodville soils: have A horizons less than 51 cm (20 in)thick and are on nearby gentle slopes.
Splendora soils: have fine-loamy control sections, base saturation greater than 35 percent, occur on lower footslopes, have oxyaquic conditions
DRAINAGE AND PERMEABILITY:
Drainage class: moderately well
Internal drainage: moderate above the horizons containing plinthite and slow in the horizons having plinthite
Permeability class: slow
Runoff: low on 0 to 1 percent slopes, medium on 1 to 5 percent slopes, and high on 5 to 12 percent slopes
USE AND VEGETATION: Most areas are in timber. Some have been cleared for row crops and pasture. Native vegetation is shortleaf, longleaf, and loblolly pine with such hardwoods as sweetgum, post oak, red oak, and hickory. Understory is yaupon, wax-myrtle, American beautyberry, bay, and viburnum. Many areas of Conroe soils have been surface mined for the ironstone nodules.
DISTRIBUTION AND EXTENT:
General area: South-eastern Texas
Land Resource Region: P - South Atlantic and Gulf Slope Cash Crops, Forest, and Livestock Region and T - Atlantic and Gulf Coast Lowland Forest and Crop Region;
Major Land Resource Area: MLRA 133B - Western Coastal Plain and MLRA 152B - Western Gulf Coast Flatwoods
Extent: extensive
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Walker County, Texas; 1975.
REMARKS: Diagnostic horizons and features recognized in the pedons are:
Ochric epipedon - 0 to 64 cm (0 to 25 in). (A and E horizons)
Albic horizon - 10 to 64 cm (4 to 25 in). (E horizon)
Arenic feature - 0 to 64 cm (0 to 25 in) is loamy fine sand or coarser. (A and E horizons)
Argillic horizon - 64 to 198 cm (25 to 78 in). (Bt and Btv horizons)
Plinthic feature - 79 to 244 cm (31 to 96 in). (Btv and BCv horizons)
ADDITIONAL DATA: Data from National Soil Survey Laboratory published in SS1R-30; S64TX-170-5(64275-64284) and S64TX-170-6(64285-64294) indicate 44 to 49 percent clay in the Bt horizon and more than 50 percent kaolinite and a base saturation of about 20 percent at 127 cm (50 in) below the top of the Bt horizon.
Taxonomic Version: Keys to Soil Taxonomy, Twelfth Edition, 2014.
National Cooperative Soil Survey
U.S.A.