LOCATION OAKALLA TX
Established Series
Rev. MLG-WJG-RM
08/2017
OAKALLA SERIES
The Oakalla series consists of soils that are very deep. These well drained soils formed in loamy alluvium derived from limestone of Cretaceous age. These soils are on nearly level to gently sloping on flood plains on perennial streams in river valleys. They are subject to flooding by overflow from streams for short periods after heavy rains. Slopes are 0 to 2 percent. Mean annual temperature is about 19 degrees C (67 degrees F), and mean annual precipitation is about 737 mm (29 in).
TAXONOMIC CLASS: Fine-loamy, carbonatic, thermic Cumulic Haplustolls
TYPICAL PEDON: Oakalla silty clay loam--in cropland. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 20 cm (0 to 8 in); dark grayish brown (10YR 4/2) silty clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; hard, friable, sticky and plastic; common very fine and fine roots; common fine pores; few very fine weakly cemented masses of calcium carbonate; about 33 percent calcium carbonate equivalent; violently effervescent; moderately alkaline; abrupt smooth boundary. (Thickness of the Ap horizon is 13 to 38 cm [5 to 15 in])
Ak1--20 to 41 cm (8 to 16 in); dark grayish brown (10YR 4/2) silty clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; hard, friable, sticky and plastic; common very fine and fine roots; common fine pores; few very fine weakly cemented masses of calcium carbonate; about 33 percent calcium carbonate equivalent; violently effervescent; moderately alkaline; gradual smooth boundary.
Ak2--41 to 58 cm (16 to 23 in); dark grayish brown (10YR 4/2) silty clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; hard, firm, sticky and plastic; common very fine and fine roots; common fine pores; few very fine weakly cemented nodules of calcium carbonate; violently effervescent; moderately alkaline; about 41 percent calcium carbonate equivalent; gradual smooth boundary. (Combined thickness of the Ak horizon is 30 to 81 cm [12 to 32 in])
Bk1--58 to 135 cm (23 to 53 in); brown (10YR 5/3) silty clay loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; hard, firm, sticky and plastic; few very fine roots; few fine pores; few films and threads of calcium carbonate; few weakly cemented nodules of calcium carbonate; about 50 percent calcium carbonate equivalent; few shell fragments; few dark streaks of A material; violently effervescent; moderately alkaline; gradual smooth boundary. (Combined thickness of the Bk horizon is 84 to 160 cm [33 to 63 in])
Bk2--135 to 203 cm (53-80 in); yellowish brown (10YR 5/4) silty clay loam, dark yellowish brown (10YR 4/4) moist; moderate fine and medium subangular blocky structure; hard, friable, sticky and plastic; few very fine roots; few fine pores; about 3 percent by volume films, threads, and soft masses of calcium carbonate, mainly in the lower part; few strongly cemented nodules of calcium carbonate; violently effervescent; moderately alkaline.
TYPE LOCATION: Blanco County, Texas; From the intersection of U.S. Highway 290 and Ranch Road 1, approximately 0.5 mile west of Hye, about 0.1 mile west on Ranch Road 1, then 150 ft north in cultivated field.
USGS topographic quadrangle: Hye, TX;
Latitude: 30 degrees, 14 minutes, 31.6 seconds N;
Longitude: 98 degrees, 34 minutes, 43.7 seconds W;
Datum: NAD83.
RANGE IN CHARACTERISTICS:
Solum thickness: 150 to 203 cm (60 to 80 in)
Coarse fragments: Amount-0-10 percent by volume, kind-limestone, size-2 to 75 mm
Mollic epipedon: more than 50 cm (20 in) thick
Identifiable secondary carbonate: Amount-0 to 5 by volume, size-fine to medium, contrast-distinct, kind-concretions, masses, or nodules
Particle-size control section (weighted average):
Calcium carbonate equivalent: 40 to 60 percent by weight
Ap and Ak horizons:
Hue: 7.5YR or 10YR
Value: 2 to 5, 2 to 3 moist
Chroma: 1 to 3, dry and moist
Texture: clay loam, silty clay loam, silty clay, or clay
Carbonate clay: 5 to 12 percent by weight
Reaction: moderately alkaline
Bk horizon:
Hue: 7.5YR or 10YR
Value: 3 to 7, dry and moist
Chroma: 2 to 6, dry and moist
Texture: loam, clay loam, silty clay loam, or fine sandy loam; some pedons have layers with textures of fine sandy loam or clay.
Identifiable secondary carbonates: Amount-0 to 5 percent by volume, size-fine to medium, contrast-distinct, kind-concretions, masses, or nodules
Reaction: moderately alkaline
Other features: Some pedons have Ab horizons below 76 cm (30 in).
COMPETING SERIES: There are no competing series in this family. Similar series in other families are
Bergstrom (TX+OK),
Bigetty (NM+TX),
Bippus (TX),
Bosque (TX),
Clearfork (TX),
Elandco (TX+KS OK),
Frio (TX),
Gageby (TX),
Gowen (TX+OK),
Iraan (TX),
Nipsum (TX+OK),
Port (OK+KS+TX),
Stanford (AZ),
Westfork (TX), and
Whitesboro (TX) serie.s.
Bippus,
Bosque,
Gageby,
Gowen,
Stanford and
Whitesboro soils: have mixed mineralogy and less than 40 percent calcium carbonate in the control section.
Bergstrom,
Bigetty,
Clearfork,
Elandco,
Iraan, and
Port soils: have 27 to 35 percent clay and less than 15 percent sand coarser than very fine sand in the particle-size control section.
Frio,
Nipsum, and
Westfork soils: have greater than 35 percent clay in the particle-size control section.
GEOGRAPHIC SETTING:
Parent material: Formed in loamy calcareous alluvium derived from limestone of Cretaceous age.
Landscape: River valley
Landform: Occur on flood plains on perennial streams
Slope: 0 to 2 percent
Climate: Dry subhumid
Soil moisture: Typic ustic moisture regime.
Precipitation Pattern: The majority of the yearly amount occurs during the fall and spring months. The winter and summer months are normally drier.
Mean annual air temperature: 18 to 21 degrees C (64 to 70 degrees F)
Mean annual precipitation: 610 to 867 mm (24 to 34 in)
Frost free period: 210 to 240 days
Elevation: 122 to 612 m (400 to 2,000 ft)
Thornthwaite annual P-E indices: 36 to 46
GEOGRAPHICALLY ASSOCIATED SOILS: These include the
Bolar (TX),
Doss (TX),
Heaton (TX),
Karnes (TX),
Krum (TX),
Lewisville (TX),
Pedernales (TX), and
Purves (TX).
Bolar,
Doss, and
Purves soils: occur on summit, shoulders and ridges of dissected plateaus.
Heaton,
Karnes, and
Krum soils: are on flood plains and on similar landscape positions.
Lewisville and
Pedernales soils: are on terraces, alluvial plain remnants, or in valleys of dissected plateaus.
DRAINAGE AND PERMEABILITY:
Drainage class: Well.
Permeability class: Moderate.
Runoff: negligible on 0 to 1 percent slopes and low on 1 to 2 percent slopes.
Wetness: the soil floods at 1 to 10 year intervals, except where protected by dams.
USE AND VEGETATION: Most areas are being used for farmland, pastureland, and rangeland. The areas farmed are mainly in sorghums and small grains. Some areas are used for improves pastures. The climax plant community is a semi-wooded flood plain that has trees shading as much as 15 percent of the area along the water courses. Native trees are scattered elm, pecan, hackberry, and cottonwood. Away from the water courses, there are tall and mid grasses with occasional trees. The dominant plants are big bluestem, little bluestem, and vine mesquite. Other grasses include yellow Indiangrass, eastern gamagrass, switchgrass, southwestern bristlegrass, Canada wildrye, purple tridens, broadleaf uniola, Scribners panicum, plains lovegrass, Texas wintergrass, sideoats grama, cane bluestem and buffalograss. Woody plants include pecan, walnut, oaks, elms, mulberry, sycamore, wafer ash, button willow, wild grape, hackberry, greenbriar, honeysuckle, peppervine, and poison ivy or poison oak. Forbs include Maximilian sunflower, bushsunflower, Engelmann daisy, blood ragweed, and yellow neptunia. With heavy stocking rates the site could potentially deteriorate to a plant population of meadow dropseed, vine-mesquite, silver bluestem, sideoats grama, buffalograss, and mesquite. If this destructive grazing practice is continued the site will deteriorate to an understory plant community of prickly pear, buffalograss, threeawn, Texas wintergrass, red grama, and annual weeds and grasses with a dense overstory of oak, elm, mesquite, and hackberry. Extensive shading by trees and thicket-forming plants is a major management problem on this site.
DISTRIBUTION AND EXTENT: Southwest Plateaus and Plains Range and Cotton Region, LLR-I: MLRA 81B-Edwards Plateau, Central Part and MLRA 81C-Edwards Plateau, Eastern Part. Southwestern Praries Cotton and Forage Region, LRR-J: MLRA 85-Grand Prairie and MLRA 86A-Texas Blackland Prarie, Northern Part. This series is of large extent with about 150,000 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Blanco County, Texas; 1977.
REMARKS: Oakalla soils were included with Bosque and Frio soils.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: 0 to 58 cm (0 to 23 in) (A and Ak horizons)
Cambic horizon: 58 to 203 cm (23 to 80 in) (Bk horizons)
ADDITIONAL DATA: None
Taxonomic Version: Soil Taxonomy, Twelfth Edition, 2014.
National Cooperative Soil Survey
U.S.A.