LOCATION OLMEDO TX

Established Series
PDH-JLS-CLN
11/2010

OLMEDO SERIES

The Olmedo series consists of soils that are very shallow and shallow over a petrocalcic horizon. These well drained, moderately permeable soils formed in calcareous, loamy residuum of the Goliad Formation of Miocene-Pliocene age. These nearly level to undulating soils are on summits on interfluves or ridges. Slope ranges from 1 to 8 percent. Mean annual air temperature is about 22 degrees C (72 degrees F) and mean annual precipitation is about 711 mm (28 in).

TAXONOMIC CLASS: Loamy-skeletal, carbonatic, hyperthermic, shallow Petrocalcic Calciustolls

TYPICAL PEDON: Olmedo very gravelly fine sandy loam--on a southeast facing, convex, 3 percent slope in rangeland at an elevation of 70 m (230 ft). (Colors are for dry soil unless otherwise noted.)

A1--0 to 20 cm (0 to 8 in); very dark grayish brown (10YR 3/2) very gravelly fine sandy loam, very dark gray (10YR 3/1) moist; weak fine subangular blocky and granular structure; soft, very friable, nonsticky and nonplastic; many fine roots; few snail shell fragments, common fine irregular nodules of calcium carbonate; common wormcasts; 58 percent, by volume, indurated platy and irregular shaped petrocalcic fragments with 5 percent larger than 8 cm (3 in) and 53 percent smaller than 2 cm (0.75 in) in diameter; strongly effervescent; slightly alkaline; clear wavy boundary.

A2--20 to 46 cm (8 to 18 in); brown (10YR 4/3) extremely gravelly sandy clay loam, dark brown (10YR 3/3) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; common fine and medium roots; few snail shell fragments; common fine irregular nodules of calcium carbonate; common wormcasts; 78 percent by volume indurated platy and irregular shaped petrocalcic fragments with approxamately 15 percent larger than 8 cm (3 in) and 63 percent smaller than 2 cm (0.75 in) in diameter; violently effervescent; moderately alkaline; abrupt smooth boundary. (combined thickness of the A horizon is 28 to 51 cm [11 to 20 in])

Bkkm--46 to 76 cm (18 to 30 in); 70 percent white (10YR 8/1) and 30 percent very pale brown (10YR 8/3), indurated calcium carbonate; 70 percent white (10YR 8/1) and 30 percent very pale brown (10YR 7/3) moist; massive; extremely hard, extremely firm, nonsticky and nonplastic; common fine and medium roots matted on top of the petrocalcic and along fractured seams that are more than 10.2 cm (4 in) apart; violently effervescent; moderately alkaline, gradual wavy boundary. (thickness of the Bkkm horizon is 51 to 89 cm [20 to 35 in])

BCkk1--76 to 104 cm (30 to 41 in); white (10YR 8/1), weakly cemented calcium carbonate, white (10YR 8/1) moist; massive; extremely hard, very firm, nonsticky and nonplastic; few fine roots in cracks; many fine and medium masses of calcium carbonate; violently effervescent; strongly alkaline; gradual wavy boundary.

BCkk2--104 to 130 cm (41 to 51 in); white (10YR 8/1), weakly cemented caliche; white (10YR 8/1) moist; massive; extremely hard, very firm, nonsticky and nonplastic; few fine roots in cracks; many fine and medium masses of calcium carbonate; violently effervescent; strongly alkaline; gradual wavy boundary.

BCk3--130 to 157 cm (51 to 61 in); white (10YR 8/1), weakly cemented caliche; white (10YR 8/1) moist; massive; extremely hard, very firm, nonsticky and nonplastic; few fine roots in cracks; many fine and medium masses of calcium carbonate; 2 percent by volume rounded chert fragments; 20 percent by volume rounded weakly cemented calcium carbonate fragments; violently effervescent; moderately alkaline; gradual wavy boundary.

BCk4--157 to 191 cm (61 to 75 in); white (10YR 8/1), weakly cemented caliche; white (10YR 8/1) moist; massive; extremely hard, very firm, nonsticky and nonplastic; few fine roots in cracks; 20 percent by volume medium size calcite crystals surrounded by soft powdery calcium carbonate masses; many fine and medium masses of calcium carbonate, 2 percent by volume rounded chert fragments; 20 percent by volume rounded weakly cemented calcium carbonate fragments; violently effervescent; moderately alkaline; gradual way boundary. (combined thickness of the BCkk and BCk horizon is 64 to 140 cm [25 to 55 in])

BCk5--191 to 203 cm (75 to 80 in); pink (7.5YR 7/3), weakly cemented caliche; light brown (7.5YR 6/4) moist; massive; extremely hard, very firm, nonsticky and nonplastic; few fine roots in cracks; 20 percent by volume rounded weakly cemented calcium carbonate fragments; 20 percent by volume medium size calcite crystals surrounded by soft powdery calcium carbonate; many fine and medium masses of calcium carbonate; 2 percent by volume rounded chert fragments; violently effervescent; moderately alkaline.

TYPE LOCATION: Live Oak County, Texas: from the intersections of U.S. Highway 281 and U.S. Highway 59 in George West; 5.5 miles east on U.S. Highway 59 to Interstate Highway 37; 9.3 miles south on Interstate Highway 37 to Farm Road 534; 5.4 miles west on Farm Road 534 to county road; 2.9 miles southwest and south on county road; 500 feet east in rangeland. Crater Ridge, Texas USGS topographic quadrangle. Latitude:28 degrees, 10 minutes, 51 seconds N; Longitude: 98 degrees, 0 minutes, 47 seconds W.; NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: An ustic moisture regime bordering on aridic. The soil moisture control section remains moist in some or all parts for less than 90 consecutive days in normal years. The soil is driest during the months June through August and December through February. These soils are intermittently moist in September through November and March through May.
Mean annual soil temperature: 21 to 23 degrees C (70 to 73 degrees F)
Depth to petrocalcic horizon: 30 to 46 cm (12 to 18 in)

Particle size control section (weighted average)
Clay content: 12 to 24 percent
Rock Fragments: 35 to 85 percent

A horizon
Hue: 7.5YR or 10YR
Value: 3 to 5
Chroma: 1 to 3
Texture: fine sandy loam, loam, or sandy clay loam (gravelly, very gravelly, or extremely gravelly counterparts)
Clay content: 12 to 22 percent
Rock fragments: 35 to 85 percent
Calcium carbonate equivalent: 10 to 70 percent
EC (dS/m): 0 to 1
SAR: 0 to 1
Effervescence: strong to violent
Reaction: slightly alkaline or moderately alkaline

Bkkm horizon
Hue: 10YR
Value: 8
Chroma: 1 or 2
Texture: indurated calcium carbonate (petrocalcic)
Calcium carbonate equivalent: 40 to 80 percent
EC (dS/m): 0 to 1
SAR: 0 to 1
Effervescence: violently effervescent
Reaction: slightly alkaline or moderately alkaline

BCkk or BCk horizon
Hue: 7.5 YR or 10YR
Value: 7 or 8
Chroma: 1 to 3
Texture: sandy loam or silt loam and gravelly, very gravelly or extremely gravelly counterparts
Clay content: 4 to 12 percent
Rock fragments: 2 to 40 percent
Calcium carbonate equivalent: 40 to 75 percent
Identifiable secondary carbonate: amount-10 to 40 percent, size-fine and medium, kind-masses, location-throughout
EC (dS/m): 1 to 5
SAR: 0 to 14
Effervescence: strongly or violently effervescent
Reaction: slightly alkaline or moderately alkaline

COMPETING SERIES: This is the Olmos (TX) series. Similar soils are the Cuevitas (TX), Delmita (TX), Lacoste (TX), and Randado (TX) series.
Olmos soils: contain limestone fragments and are in a slightly drier climate.
Cuevitas and Lacoste soils: have a loamy particle-size control section
Delmita soils: have a fine-loamy particle-size control section
Randado soils: have an ochric epipedon

GEOGRAPHIC SETTING:
Parent material: Calcareous, loamy residuum of the Goliad Formation of Miocene-Pliocene age
Landform: summit and shoulder slopes on interfluve or ridge
Slope: 1 to 8 percent
Mean annual air temperature: 21 to 23 degrees C (70 to 73 degrees F)
Mean annual precipitation: 457 to 813 mm (18 to 32 in)
Frost-free period: 250 to 300 days
Elevation: 50 to 213 m (160 to 695 ft)
Thornthwaite annual P-E indices: 19 to 31

GEOGRAPHICALLY ASSOCIATED SOILS: These soils are the Lacoste, Pernitas, Pettus, and Sarnosa series.
Lacoste soils: are on similar positions and have an argillic horizon
Pernitas soils: are on lower shoulder and backslope positions and have an argillic horizon
Pettus soils: are on slightly lower shoulder positions and do not have a petrocalic horizon
Sarnosa soils: are on lower shoulder and backslope positions and do not have a petrocalcic horizon

DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate above the impermeable petrocalcic layer. Runoff is medium.

USE AND VEGETATION: The major uses are livestock grazing and wildlife habitat. Native vegetation consists of Arizona cottontop, pinhole bluestem, plains bristlegrass, sideoats grama, cenizo, guajillo, elbowbush, mescalbean, vine ephedra, and Texas Kidneywood. The ecological site is Shallow Ridge, PE 19-31 (RO83CY485TX)

DISTRIBUTION AND EXTENT: Northern Rio Grande Plain (MLRA 83A in LRR I) and Central Rio Grande Plain (MLRA 83C in LRR I) of southern Texas. The series is of moderate extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: Live Oak County, Texas, 2007.

REMARKS: The series was formerly included in the Olmos series.
Diagnostic horizons and features recognized in this pedon are:

Particle size control section: 25 to 46 cm (10 to 18 in). (A2 horizon)
Mollic epipedon: 0 to 46 cm (0 to 18 in). (A1 and A2 horizons)
Petrocalcic horizon: 46 to 76 cm (18 to 30 in). (Bkkm horizons)
Skeletal feature: more than 35 percent by volume of rock fragments in the control section

ADDITIONAL DATA: NSSL data from Live Oak County, TX (S91TX-297-001)

TAXONOMIC VERSION: Keys to Soil Taxonomy, Eleventh Edition, 2010

National Cooperative Soil Survey
U.S.A.