LOCATION MERETA                  TX

Established Series


The Mereta series consists of well drained, moderately slowly permeable soils that are shallow to a petrocalcic horizon. These soils formed in clayey calcareous alluvium and colluvium derived from limestone. These nearly level to gently sloping soils occur on stream terraces, alluvial fans and knolls on dissected plateaus. Slope ranges from 0 to 5 percent. Mean annual precipitation is about 635 mm (25 in) and mean annual air temperature is about 19 degrees C (66 degrees F).

TAXONOMIC CLASS: Clayey, mixed, superactive, thermic, shallow Petrocalcic Calciustolls

TYPICAL PEDON: Mereta clay loam--cultivated.
(Colors are for dry soil unless otherwise stated.)

Ap--0 to 12 cm (0 to 5 in); dark grayish brown (10YR 4/2) clay loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; hard, friable; few fine roots; few fine calcium carbonate fragments; strongly effervescent; moderately alkaline; abrupt smooth boundary. Thickness is 7.6 to 30 cm (3 to 12 in)

Bw1--12 to 28 cm (5 to 11 in); brown (7.5YR 4/2) clay loam, dark brown (7.5YR 3/2) moist; moderate fine subangular blocky structure; hard, friable; few fine roots; strongly effervescent; moderately alkaline; gradual smooth boundary.

Bw2--28 to 48 cm (11 to 19 in); brown (7.5YR 4/3) clay loam; dark brown (7.5YR 3/3) moist; moderate fine subangular blocky structure; hard, firm; few fine roots; few fine pores; common calcium carbonate fragments; violently effervescent; moderately alkaline; abrupt wavy boundary. Combined thickness of the Bw horizon is 15 to 38 cm (6 to 15 in)

Bkkm--48 to 58 cm (19 to 23 in); pinkish white (7.5YR 8/2) caliche; strongly cemented and platy; 1 percent or less of fine earth between plates and in solution channels; violently effervescent; moderately alkaline; clear wavy boundary. Thickness is 10 to 46 cm (4 to 18 in)

BCkk--58 to 102 cm (23 to 40 in); pink (7.5YR 8/4) loam, light brown (7.5YR 6/4) moist; massive; soft, friable; 50 percent calcium carbonate consisting of fine disseminated particles, masses and concretions; violently effervescent; moderately alkaline; gradual smooth boundary. Thickness is 15 to 51 cm (6 to 20 in)

BCk--102 to 152 cm (40 to 60 in); light brown (7.5YR 6/4) clay loam, brown (7.5YR 5/4) moist; massive; soft, friable; 15 to 20 percent calcium carbonate masses and concretions; violently effervescent; moderately alkaline.

TYPE LOCATION: McCulloch County, Texas; From the intersection of Highway 190 and FM 1121 in Rochelle, 1.5 miles southwest on U.S. Highway 190, and 250 feet northwest in pasture.
USGS topographic quadrangle: Rochelle, TX; Latitude: 31 degrees, 12 minutes, 23.0 seconds N; Longitude: 99 degrees, 13 minutes, 38.0 seconds W; Datum: NAD83.

Soil moisture: Typic-ustic moisture regime
Depth to petrocalcic contact: 35 to 50 cm (14 to 20 in)
Cementation: Strongly cemented or indurated
Effervescence: Strongly to violently
Reaction: Slightly alkaline or moderately alkaline

Particle-size control section (weighted average):
Total clay content: 35 to 45 percent
Carbonate clay content: 7 to 11 percent
Coarse fragments: 0 to 10 percent; 2 to 75 mm, angular cemented calcium carbonate

A horizon
Hue: 7.5YR or 10YR
Value: 3 to 5
Chroma: 2 or 3
Texture: Clay loam, silty clay loam, or clay
Total clay content: 35 to 45 percent
Carbonate clay content: 4 to 6 percent
Calcium carbonate equivalent: 5 to 20 percent

Bw horizon
Hue: 5YR to 10YR
Value: 4 to 8
Chroma: 2 to 4
Texture: Clay loam, silty clay loam, or clay; and gravelly or very gravelly phases
Total clay content: 35 to 45 percent
Carbonate clay content: 7 to 11 percent
Coarse fragments: 0 to 55 percent; 2 to 75 mm (0.25 to 3 in), cemented calcium carbonate
Calcium carbonate equivalent: 15 to 40 percent

Bkkm horizon
Hue: 5YR to 10YR
Value: 7 or 8
Chroma: 2 to 3
Cementation: Strongly cemented to indurated, 1 to 5 cm is laminar
Other features: The boundary between the Bw and the Bkkm horizon is clear to abrupt, and wavy to irregular.

Bk, Bkk, BCkk, or BCk horizons
Hue: 7.5YR to 2.5Y
Value: 6 or 8
Chroma: 1 to 4
Texture: Loam, clay loam, or silty clay loam; and/or their gravelly phases
Total clay content: 20 to 40 percent
Carbonate clay content: 9 to 20 percent
Coarse fragments: 0 to 35 percent
Identifiable secondary carbonate: 35 to 70 percent; fine to medium, masses and concretions
Calcium carbonate equivalent: 35 to 80 percent

COMPETING SERIES: There are no series in the same family. Similar soils are the Cho, Eola, Kavett, Mailtrail, Noelke, Ozona, Pitzer, Queeny, and Valera series.
Cho, Eola, Noelke, Ozona, Pitzer, and Queeny soils: have less than 35 percent clay in the particle-size control section.
Cho soils: have carbonatic mineralogy.
Eola and Mailtrail soils: have more than 35 percent coarse fragments in the particle-size control section.
Kavett and Valera soils: have a petrocalcic horizon underlain by indurated limestone bedrock.
Noelke soils: have a lithic contact within 50 cm of the surface.

Parent material: Clayey calcareous alluvium or colluvium derived from limestone.
Landscape: dissected plateaus
Landform: Stream terraces, alluvial fans and/or knolls
Slope: 0 to 5 percent.
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 precipitation: 432 to 711 mm (17 to 28 in)
Thornthwaite annual P-E index: 24 to 42
Mean annual air temperature: 17.2 to 21.1 degrees C (64 to 70 degrees F)
Frost-free period: 210 to 240 days
Elevation: 335.3 to 853.4 m (1,100 to 2,800 ft)

GEOGRAPHICALLY ASSOCIATED SOILS: These are Cho, Kavett, Nuvalde, Rowena and Valera series.
Cho soils: occurs on similar landscape positions
Kavett and Valera soils: are underlain by limestone bedrock and occur on backslope and footslope positions
Nuvalde and Rowena soils: do not have a petrocalcic horizon

DRAINAGE AND PERMEABILITY: Well drained. Permeability of the soil is moderately slow. Permeability of the petrocalcic horizon is slow to very slow. Runoff is medium on 0 to 1 percent slopes and high on 1 to 5 percent slopes.

USE AND VEGETATION: Cultivation and rangeland. Cultivated crops are small grain, and grain sorghum. The climax plant community is a mid grass prairie. The dominant grasses are little bluestem and sideoats grama. Other grasses include Texas wintergrass, silver bluestem, Arizona cottontop, dropseeds, slim tridens, green sprangletop, buffalograss, Wright's threeawn, plains bristlegrass, and curly mesquite. The woody plant is live oak. Forbs include bushsunflower, orange zexmenia, and gayfeather. With heavy stocking rates the site could potentially deteriorate to a plan population of buffalograss, curly mesquite, threeawns, agarito, and lotebush. If destructive grazing practices continue, the site will revert to a plant population of lotebush, prickly pear, Texas persimmon, tasajillo, agarito, threeawns, red grama, Texas grama, hairy tridens, prairie coneflower, and broomweed.

DISTRIBUTION AND EXTENT: Central and North Texas; Central Great Plains Winter Wheat and Range Region, LRR H: MLRA 78A-Rolling Limestone Prairie. Southwest Plateaus and Plains Range and Cotton Region, LLR I: MLRA 81A-Edwards Plateau, Western Part; and MLRA 81B-Edwards Plateau, Central Part. The series is extensive with over 500,000 acres.


SERIES ESTABLISHED: Brown County, Texas; 1939.

REMARKS: NSSL data from a pedon near the type location classifies in a loamy particle size class when carbonate clay is subtracted from total clay. Because the series is extensive the classification was not changed pending a study over the whole series extent.

Edited 11/2013 (RFG-JRJ): Added total and carbonate clay content and calcium carbonate equivalent to horizons in RIC. Updated the competing series, geographic setting, and associated soils sections.

Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: 0 to 48 cm (0 to 19 in) (A and Bw horizons)
Petrocalcic horizon: 48 to 58 cm (19 to 23 in) (Bkkm horizon)
Calcic horizon: 58 to 152 cm (23 to 60 in) (BCkk and BCk horizons)

ADDITIONAL DATA: KSSL data from McCullogh County, TX, pedon S09TX307004 (lab number 09N2917- 09N02922)

Taxonomic Version: Keys to Soil Taxonomy, Eleventh Edition, 2010.

National Cooperative Soil Survey