LOCATION DUFFAU TX+OKEstablished Series
TAXONOMIC CLASS: Fine-loamy, siliceous, active, thermic Udic Paleustalfs
TYPICAL PEDON: Duffau fine sandy loam--wooded pasture. (Colors are for dry soil unless otherwise stated.)
A--0 to 4 inches; dark grayish brown (10YR 4/2) fine sandy loam, very dark grayish brown (10YR 3/2) moist; weak very fine subangular blocky and granular structure; slightly hard, friable; many fine roots; slightly alkaline; clear smooth boundary. (2 to 8 inches thick)
E--4 to 10 inches; pale brown (10YR 6/3) fine sandy loam, brown (10YR 4/3) moist; weak fine granular structure; slightly hard, friable; many fine roots; neutral; clear smooth boundary. ( 4 to 12 inches thick)
Bt1--10 to 40 inches; yellowish red (5YR 5/6) sandy clay loam, yellowish red (5YR 4/6) moist; moderate fine subangular blocky structure; hard, firm, common fine roots; common distinct clay films on faces of peds and bridging sand grains; slightly acid; gradual wavy boundary. (20 to 35 inches thick)
Bt2--40 to 54 inches; yellowish red (5YR 4/6) sandy clay loam, yellowish red (5YR 4/6) moist; weak coarse subangular blocky structure; hard, firm; few fine roots; common distinct clay films on faces of peds and bridging sand grains; neutral; gradual wavy boundary. (8 to 24 inches thick)
Bt3--54 to 70 inches; yellowish red (5YR 5/6) sandy clay loam, yellowish red (5YR 4/6) moist, with a few fine faint mottles of strong brown (7.5YR 5/6); weak coarse subangular blocky structure; hard, friable; few fine roots; few faint clay films on faces of peds. neutral; gradual wavy boundary. (6 to 24 inches thick)
BC--70 to 82 inches; reddish yellow (7.5YR 6/6) sandy clay loam, strong brown (7.5YR 5/6) moist; with a few fine faint yellowish red mottles; weak coarse subangular blocky, hard, friable, few fine roots; neutral.
TYPE LOCATION: Erath County, Texas; from the intersection of Farm Roads 219 and 8 in Lingleville, Texas; 4 miles northeast on Farm Road 219; then 0.8 mile north on a county road and 300 feet east of the road in a wooded pasture.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 60 to more than 80 inches. Siliceous or ironstone pebbles range from none to a few throughout. The base saturation ranges from 75 to about 90 percent in some part of the argillic horizon.
The A horizon has colors in shades of brown with hue of 7.5YR or 10YR, value of 4 to 6, and chroma of 2 to 4. Horizons with moist value of 3 are less than 7 inches thick. The E horizon has hue of 7.5YR or 10YR value of 5 to 7 and chroma 2 to 4. Texture of the A and E horizons is fine sandy loam, very fine sandy loam, or loamy fine sand. The reaction ranges from slightly acid to slightly alkaline.
The Bt horizon has colors in shades of red, yellow, or brown with hue of 2.5YR to 7.5YR, value of 4 to 6, and chroma of 3 to 8. Typically, there are few to common reddish, yellowish, or brownish mottles in the lower part. The texture is sandy clay loam, loam, or clay loam with an average clay content in the control section ranging from 20 to 30 percent. Some pedons have uncoated sand grains on the surface of peds or thin streaks in the matrix in the lower part. Reaction ranges from moderately acid to neutral.
The BC or C horizon, when encountered, has colors in shades of brown, pink, or yellow. The texture is fine sandy loam, sand clay loam, or very fine sandy loam. Some C horizons are weakly cemented packsand or sandstone with or without strata of shale sandy clay loam, clay, or other loamy materials. Some pedons have thin strata of weakly calcareous materials or a few calcium carbonate concretions. The reaction ranges from slightly acid to slightly alkaline.
COMPETING SERIES: These include the Bastsil and Flynn series in this family and the Bastrop, Gasil, Keeter, Konawa, Stephenville, and Weatherford series in similar families. Bastsil soils formed in alluvium and have B/E horizon. Flynn soils have hue redder than 5YR in the BE horizons and have formed in glauconitic materials. Bastrop and Konawa soils are terrace soils with mixed mineralogy. Keeter soils have a fine-silty control section. Gasil, Stephenville and Weatherford soils have base saturation less than 75 percent. In addition, Stephenville and Weatherford soils have sola less than 60 inches thick.
GEOGRAPHIC SETTING: Duffau soils occupy gently sloping to sloping erosional uplands typically in concave positions. Slope gradients range from 0 to about 8 percent. The soils formed in sands, sandy clay loam, and weakly cemented sandstones, mainly in Trinity and Paluxy sands of Lower Cretaceous age. The climate is dry subhumid; average annual precipitation ranges from 28 to 35 inches; Thornthwaite annual P-E indices range from 44 to 56 and the mean annual temperature ranges from 62 to 67 degrees F. Frost free period is 220 to 250 days and elevation ranges from 800 to 1400 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Keeter and Weatherford series and May, Nimrod, Selden, and Windthorst series. Keeter and Weatherford soils are slightly higher on low hills or ridges. May soils have a dark colored surface layer and are in a lower position in the landscape. Nimrod and Selden soils are moderately well drained with mottled subsoils. These soils are on similar or slightly lower portions. Windthorst soils have clayey subsoils and are slightly higher on low hills or ridges.
DRAINAGE AND PERMEABILITY: Well drained; runoff is negligible on 0 to 1 percent slopes, low on 1 to 5 percent slopes, and medium on 5 to 8 percent slopes; moderate permeability.
USE AND VEGETATION: Mainly used for pasture, but the soil was extensively cultivated in the past. Some areas are cultivated, with peanuts, sorghums, and small grains being the main crops. Native vegetation is mostly post oak and blackjack oak, with an understory of little bluestem, indiangrass, greenbriers, and annual grasses.
DISTRIBUTION AND EXTENT: Cross Timbers area of central and north-central Texas and south-central Oklahoma. The soil is moderately extensive.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Parker County, Texas; 1973.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Ochric epipedon - 0 to 10 inches.
Argillic horizon - 10 to 70 inches.