LOCATION YOLOGO TXEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, active, hyperthermic, shallow Petrocalcic Paleustolls
TYPICAL PEDON: Yologo gravelly loam--rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 5 inches; reddish brown (5YR 4/3) gravelly loam, dark reddish brown (5YR 3/2) moist; weak fine subangular blocky structure; hard, friable; many fine roots; few fine pores and old root channels; about 20 percent rounded pebbles of chert; neutral; clear smooth boundary. (2 to 14 inches thick)
Bt--5 to 12 inches; reddish brown (5YR 4/3) extremely gravelly clay loam, dark reddish brown (5YR 3/3) moist; moderate fine angular blocky structure; very hard, firm; many fine roots; few fine pores and old root channels; patchy clay films on peds and on coarse fragments; about 75 percent rounded pebbles and cobbles of chert; slightly alkaline; abrupt wavy boundary. (5 to 12 inches thick)
Bkm--12 to 14 inches; indurated whitish caliche plates; in upper part laminar layers are 1 to 20 mm thick; contains an estimated 10 percent of soil material between the plates; violently effervescent; moderately alkaline; abrupt wavy boundary. (1/4 inch to 6 inches thick)
BCk--14 to 60 inches; whitish soft caliche of about clay loam texture; weak fine subangular blocky structure; hard, friable; about 2 percent soil material from the argillic horizon as lenses and in pockets; violently effervescent; moderately alkaline.
TYPE LOCATION: Uvalde County, Texas; from Sabinal, 15 miles south on Farm Road 187, 0.5 mile east across Sabinal River to old ranch headquarters on Fred Woodley Ranch, 2.4 miles northeast on small ranch road, 75 feet south in rangeland. Site is 0.3 mile east of windmill or 0.25 mile west of stockpond.
RANGE IN CHARACTERISTICS:
Soil Moisture: An ustic soil moisture control section bordering on aridic. The soil moisture control section is dry in some or all parts for more than 220 days but less than 260 days in normal years. June through August and December through February are the driest months. These soils are intermittently moist in September through November and March through May.
Mean annual soil temperature: 72 to 75 degrees F.
Depth to argillic horizon: 2 to 14 inches
Depth to petrocalcic horizon: 7 to 20 inches
Particle-size control section (weighted average)
Clay content: 16 to 28 percent
Coarse Fragments: 35 to 80 percent
CEC/clay ratio: 0.4 to 0.6
A Horizon
Hue: 5YR, 7.5YR, 10YR
Value: 4 or 5
Chroma: 2 or 3
Texture: gravelly or very gravelly loam, gravelly or very gravelly sandy clay loam
Clay content: 16 to 28 percent
Coarse fragments: 15 to 60 percent
Pararock fragments: 0 to 5 percent
Reaction: slightly acid or neutral
Bt Horizon
Hue: 5YR, 7.5YR, 10YR
Value: 4
Chroma: 2 to 4
Texture: very gravelly or extremely gravelly sandy clay loam, very gravelly or
extremely gravelly clay loam
Clay content: 20 to 35 percent
Clay films: few to common, faint to distinct, on ped surfaces and on coarse fragments
Coarse fragments: 35 to 80 percent
Pararock fragments: 0 to 10 percent
Calcium carbonate equivalent: 0 to 1 percent
Visible calcium carbonate: none to 1 percent fine masses
Reaction: slightly acid to slightly alkaline
Bkm Horizon
Hue: 10YR
Value: 7 or 8
Chroma: 1 to 3
From 1/4 inch thick strongly cemented or indurated with laminar cap over weakly cemented caliche to 6 inches thick strongly cemented, indurated, or laminar throughout over weakly cemented caliche.
BCk Horizon
Hue: 10YR
Value: 7 or 8
Chroma: 2 or 3
Texture: variable, but apparent field texture is loam or silt loam
Coarse fragments: 0 to 10 percent limestone or siliceous pebbles
Calcium carbonate equivalent: 50 to 80 percent
Reaction: moderately alkaline
COMPETING SERIES: There are no competing series in the same family. Similar soils are the Grava, Hindes, Quemado, and Quihi series.
Grava series: 20 to 40 inches to a petrocalcic horizon.
Hindes series: do not have a petrocalcic horizon.
Quemado series: do not have a mollic epipedon.
Quihi series: 20 to 40 inches to a petrocalcic horizon and have a typic/ustic soil
moisture control section.
GEOGRAPHIC SETTING:
Parent material: very gravelly loamy sediments derived from the Uvalde gravel
formation of Pliocene or early Pleistocene age.
Landform: Pleistocene terrace remnants.
Slope: 1 to 8 percent
Mean annual temperature: 70 to 73 degrees F.
Mean annual precipitation: 20 to 25 inches
Precipitation Pattern: dry summers and winters with intermittently moist spring
and fall.
Frost-free period: 240 to 320 days
Elevation: 400 to 1,000 feet
Thornthwaite annual P-E indices: 25 to 35
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Grava, Hindes, Olmos, Randado, Webb and Valco series.
Grava and
Hindes series: occur on similar to very slightly lower landscape
positions in map unit complexes with Yologo.
Olmos series: calcareous throughout, do not contain siliceous pebbles and
occur on similar positions.
Randado and
Valco series: contain less than 35 percent coarse fragments in the
particle size control section and occur on slightly lower positions.
Webb series: have sola greater than 60 inches and occur in nearby valleys in
lower elevations.
DRAINAGE AND PERMEABILITY: Well drained. Moderate permeability above a slowly permeable petrocalcic horizon. Runoff is medium on 1 to 5 percent slopes and high on 5 to 8 percent slopes.
USE AND VEGETATION: Used for rangeland. Under climax conditions, the dominant native grasses are pinhole bluestem, sideoats grama, pink pappusgrass, lovegrass tridens, Arizona cottontop, hooded windmillgrass, tanglehead, and plains bristlegrass. About 25 percent shrubs and 5 percent forbs also occur. With retrogression, typical increasers and invaders are blackbrush, leatherstem, threeawn, hairy tridens, and red grama.
DISTRIBUTION AND EXTENT: Northern Rio Grande Plains, Texas; LRR I; MLRA 83C. The series is of large extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
ESTABLISHED SERIES: Uvalde County, Texas, 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Particle size control section: 5 to 12 inches. (Bt horizon)
Mollic epipedon: 0 to 5 inches. (A horizons)
Argillic horizon: 5 to 12 inches. (Bt horizon)
Petrocalcic horizon: 12 to 14 inches. (Bkm horizon)
The assignment of the cation-exchange activity class is inferred from lab data from the Grava series in Duval county, Texas.
Taxonomic version: Seventh Edition, 1996