LOCATION KOURY TXEstablished Series
TAXONOMIC CLASS: Coarse-silty, siliceous, superactive, thermic Oxyaquic Eutrudepts
TYPICAL PEDON: Koury loam, 0.5 percent slope, in woodland
(Colors are for moist soil unless otherwise stated.)
A1--0 to 3 inches; pale brown (10YR 6/3) loam; weak medium subangular blocky structure; slightly hard, very friable; many medium and coarse roots; common fine pores; extremely acid; clear smooth boundary.
A2--3 to 10 inches; pale brown (10YR 6/3) very fine sandy loam; weak medium subangular blocky structure; slightly hard, very friable; many fine and medium roots; common fine pores; common fine black concretions; extremely acid; clear wavy boundary.
A3--10 to 17 inches; pale brown (10YR 6/3) loam; massive; slightly hard, very friable; many fine and medium roots; many medium pores; very strongly acid; clear wavy boundary. (combined A subhorizons are 8 to 20 inches thick)
Bw--17 to 28 inches; pale brown (10YR 6/3) silt loam; weak coarse subangular blocky structure; hard, friable; common fine and medium roots; common fine and very fine pores; common medium faint light brownish gray (10YR 6/2) iron depletions; common medium distinct yellowish brown (10YR 5/6) redox concentrations with sharp boundaries; extremely acid; gradual wavy boundary. (5 to 15 inches thick)
Bg--28 to 50 inches; light brownish gray (10YR 6/2) silt loam; weak medium subangular blocky structure; hard, friable; few fine and medium roots; few fine pores; common medium distinct yellowish brown (10YR 5/6) redox concentrations with sharp boundaries; extremely acid; gradual wavy boundary. (10 to 30 inches thick)
Ab--50 to 70 inches; dark grayish brown (10YR 4/2) silt loam; weak medium subangular blocky structure; slightly hard, friable; few fine roots; common fine and medium pores; many ped exteriors are coated with light brownish gray sand grains; common medium distinct yellowish brown (10YR 5/6) redox concentrations with sharp boundaries; few white salt crystals in lower part; extremely acid; gradual wavy boundary.
TYPE LOCATION: Angelina County, Texas; from the intersection of U.S. Highway 69 and Boykin Springs Road (Forest Service 302) south of Zavalla; 7.2 miles east on Boyken Springs Road; 0.35 mile southeast across Green Creek flood plain in woods. (Latitude 31N, 17, 54; Longitude 94W, 50, 54)
RANGE IN CHARACTERISTICS: The solum is more than 80 inches thick. Weighted average clay content of the particle-size control section ranges from 10 to 17 percent clay. Aluminum saturation ranges from 50 to 85 percent in the upper 40 inches of the soil. Base saturation ranges from 60 to 80 percent in some subhorizon at a depth of 10 to 30 inches. Redoxixmorphic features are considered both contemporary and relic. The matrix color appears to be related to the parent materials of the watershed and are litho-chromic. The soil does not have aquic soil conditions in most years.
The A horizon has hue of 10YR, value of 4 or 5, and chroma of 2 to 4; or value of 6 with chroma of 3. Texture is very fine sandy loam, silt loam or loam. Reaction ranges from extremely acid to strongly acid. The electrical conductivity ranges from 0 to 2 mmhos/cm.
The Bw horizon has hue of 10YR, value of 4 to 6, and chroma of 3 or 4. Redoximorphic features, mainly masses, in shades of red, gray, yellow, or brown range from few to common. Texture is very fine sandy loam, loam, or silt loam. Some pedons have thin bedding planes of silty clay loam or clay loam. Reaction is extremely acid or very strongly acid. The electrical conductivity ranges from 0 to 2 mmhos/cm.
The Bg horizon has hue of 10YR with value of 5 to 7, and chroma of 1 or 2. Redoximorphic features, mainly masses, in shades of red, gray, yellow, or brown range from few to common. Texture is very fine sandy loam, loam, or silt loam. Some pedons have thin bedding planes of silty clay loam or clay loam. Reaction is extremely acid or very strongly acid. The electrical conductivity ranges from 0 to 2 mmhos/cm.
Buried Ab horizons with hue of 10YR, value of 3 or 4, and chroma of 1 or 2 are typically below a depth of 40 inches. Redoximorphic features in shades of brown, red, or yellow range from none to common. Texture is very fine sandy loam, loam, silt loam, or silty clay loam. Reaction is extremely acid or very strongly acid. The electrical conductivity ranges from 1 to 4 mmhos/cm.
COMPETING SERIES: There are no other series in the same family. The Iulus, Kirkville, Marietta, Mooreville, Pophers and Sardis series are in closely related families. Iulus and Kirkville soils have a coarse-loamy particle-size control section. Marietta and Mooreville soils have a fine-loamy particle-size control section. Pophers and Sardis soils have a fine-silty particle-size control section. In addition Pophers soils are somewhat poorly drained.
GEOGRAPHIC SETTING: Koury soils are on nearly level flood plains. They formed in loamy alluvium. Slopes range from 0 to 1 percent. Mean annual rainfall ranges from 42 to 52 inches and is evenly distributed throughout the year. Summer moisture deficit ranges from 4 to 6 inches. Mean annual air temperature ranges from 65 to 68 degrees F. Frost free days range from 235 to 250. The elevation ranges from 140 to 250 above sea level. Thornthwaite annual PE indices range from 70 to 82.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the closely related Pophers series, and the Diboll, Moten, Multey, Ozias, and Penning series. Diboll Moten, Multey, and Penning soils have an argillic horizon and are on associated terraces or on low positions on uplands. Ozias and Pophers soils are on similar positions on the flood plain. These soils are more clayey and are somewhat pooorly drained.
DRAINAGE AND PERMEABILITY: Koury soils are moderately well drained and the permeability is moderately slow. Runoff is low. The soil is saturated in all layers below 2.5 to 3.5 feet for more than 30 cumulative days during the winter and spring months in normal years. These soils are subject to occasional or frequent flooding.
USE AND VEGETATION: Used mainly for timber. Some areas have been cleared and used for improved pasture. Native vegetation is mixed hardwoods with some loblolly and shortleaf pine. The understory is longleaf uniola, broomsedge bluestem and various panicums, shrubs and sedges. Pasture grasses include common bermudagrass, improved bermudagrass, and bahiagrass. Pastures are commonly overseeded with white clover.
DISTRIBUTION AND EXTENT: Western Coastal Plain (MLRA 133B) in Eastern Texas. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Angelina County, Texas; 1984.
REMARKS: This soil was formerly included in the Marietta or Mooreville soils. The classification was changed from fluvaquentic to a fluvenitic subgroup in 3/94 based on monitoring soil water and observations from local land users; then back to an Oxyaquic subgroup in 5/2000 based on peizometer data from Trinity County, Texas.
Diagnostic horizons and features recognized in the type location pedon include:
Ochric epipedon ---- 0 to 17 inches (A horizons).
Cambic horizon ----- 17 to 50 inches (Bw and Bg horizons).
Irregular organic carbon distribution -- 17 to 70 inches (Bw and Bg horizons).
ADDITIONAL DATA: Data by Texas Agricultural Experiment Station Laboratory at the type location (S80TX-005-011).