LOCATION RANCO TX+NM
Established Series
Rev. TCB-RM
09/2014
RANCO SERIES
The Ranco series consists of very deep, poorly drained, very slowly permeable soils that formed in clayey lacustrine sediments derived from Blackwater Draw Formation of Pleistocene age. These nearly level soils are on the floor of playa basins 1.5 to 15 meters (5 to 50 feet) below the surrounding plain and range in size from 5 acres to more than 50 acres. Slope ranges from 0 to 1 percent. Mean annual precipitation is 457 mm (18 in), and mean annual temperature is 16 degrees C (61 degrees F).
TAXONOMIC CLASS: Fine, smectitic, thermic Ustic Epiaquerts
TYPICAL PEDON: Ranco clay, midway between microhigh and microlow, 0.2 percent slope in playa basin at an elevation of about 902 m (2,960 ft). (Colors are for moist soil unless otherwise stated.)
A1--0 to 5 cm (0 to 2 in); very dark brown (10YR 2/2) clay, very dark grayish brown (10YR 3/2) dry; moderate fine granular structure; hard, firm; very sticky and very plastic; common very fine and fine roots; few fine prominent yellowish red (5YR 5/6) masses of iron accumulation on faces of peds; slightly effervescent; slightly alkaline; clear smooth boundary.
A2--5 to 25 cm (2 to 10 in); very dark brown (10YR 2/2) clay, very dark grayish brown (10YR 3/2) dry; moderate medium subangular blocky structure; very hard, very firm; very sticky and very plastic; common fine roots; common very fine and fine pores; cracks 1.3 cm (0.5 inch) wide extend through the horizon; few distinct black (10YR 2/1) concretions and few black (N 2.5/0) masses of iron-manganese; common fine prominent yellowish red (5YR 5/6) masses of iron accumulation on faces of peds; slightly alkaline; gradual smooth boundary. (combined A horizons are 13 to 46 cm [5 to 18 in] thick)
Bw--25 to 64 cm (10 to 25 in); very dark gray (10YR 3/1) clay, dark gray (10YR 4/1) dry; moderate medium subangular blocky structure; very hard, very firm; very sticky and very plastic; common very fine and fine roots; common very fine and fine pores; cracks 1.3 cm (0.5 inch) wide extend through the horizon; few distinct black (10YR 2/1) concretions and few black (N 2.5/0) masses of iron-manganese; common fine prominent yellowish red (5YR 5/6) masses of iron accumulation on faces of peds; few fine faint dark gray (10YR 4/1) iron depletions on faces of peds; moderately alkaline; gradual wavy boundary. (0 to 51 cm [0 to 20 in] thick)
Bss1--64 to 89 cm (25 to 35 in); dark gray (10YR 4/1) clay, gray (10YR 5/1) dry; moderate coarse wedge-shaped aggregates parting to strong medium angular blocky structure; very hard, very firm; very sticky and very plastic; common very fine and fine roots; common very fine and fine pores; cracks 1.3 cm (0.5 in) wide extend to a depth of 76 cm (30 in); common distinct slickensides; few very fine black (10YR 2/1) iron-manganese concretions; few very fine and fine calcium carbonate nodules; strongly effervescent; moderately alkaline; gradual wavy boundary.
Bss2--89 to 155 cm (35 to 61 in); dark gray (10YR 4/1) clay, gray (10YR 5/1) dry; moderate coarse wedge-shaped aggregates parting to strong medium angular blocky structure; very hard, very firm; very sticky and very plastic; common very fine and fine roots; common very fine and fine pores; common distinct slickensides; few and fine calcium carbonate nodules; strongly effervescent; moderately alkaline; gradual wavy boundary. (Combined thickness of the Bss horizons is 140 to 191 cm [55 to 75 in].)
Bss3--155 to 191 cm (61 to 75 in); dark gray (10YR 4/1) clay, gray (10YR 5/1) dry; moderate coarse wedge-shaped aggregates parting to strong medium angular blocky structure; very hard, very firm; very sticky and very plastic; few very fine and fine roots; common very fine and fine pores; common distinct slickensides; few and fine calcium carbonate nodules; strongly effervescent; moderately alkaline; gradual wavy boundary.
Bss4--191 to 229 cm (75 to 90 in); dark gray (10YR 4/1) clay, gray (10YR 5/1) dry; few fine distinct light yellowish brown (2.5Y 6/3) mottles; moderate coarse wedge-shaped aggregates parting to moderate medium angular blocky structure; very hard, very firm; very sticky and very plastic; few very fine roots; few very fine and fine pores; common distinct slickensides; few fine calcium carbonate nodules; strongly effervescent; moderately alkaline.
TYPE LOCATION: Lynn County, Texas; From the intersection of U.S. Highway 380 and U.S. Highway 87 in Tahoka; about 14.2 kilometers (8.8 miles) east on U.S. Highway 380; 644 m (0.4 mile) north in playa floor; Latitude: 33 degrees, 10 minutes, 16.2 seconds N; Longitude: 101 degrees, 38 minutes, 35.8 seconds W; New Lynn, Texas USGS quad; NAD 27.
RANGE IN CHARACTERISTICS:
Soil moisture: An aquic moisture regime. These soils receive runoff from surrounding uplands and are moist for longer periods than normal for the climate.
The soil cracks and is dry in some or all parts of the upper 51 cm (20 in) for more than 90 cumulative days in normal years. July through August and November through March are the driest months. These soils are intermittently moist in September through October and April through June. Mean annual soil temperature: 16 to 18 degrees C (60 to 65 degrees F).
Depth to secondary calcium carbonate: 25 to more than 152 cm (10 to more than 60 in).
Depth to redox concentrations: 0 to 13 cm (0 to 5 in) and range from few to many.
Depth to redox depletions: 0 to 51 cm (0 to 20 in) and range from none to common.
Depth to episaturation: 0 to 51 cm (0 to 20 in).
Depth to slickensides: 13 to 76 cm (5 to 30 in).
Solum thickness: more than 203 cm (80 in).
Particle-size control section: 40 to 50 percent silicate clay.
This is a cyclic soil and undisturbed areas have gilgai microrelief with microhighs 8 to 13 cm (3 to 5 in) higher than microlows. Distance between the center of the microhigh and the center of the microlow is about 1.5 to 4.6 m (5 to 15 ft). The microhigh makes up about 20 percent, the intermediate, or area between the high and low, about 40 percent, and the microlow about 40 percent. Cracks open and close each year, except during higher than normal rainfall years and remain open for 90 or more cumulative days during most years. When dry, 1 to 5 cm (0.4 to 2 in) wide cracks extend from the surface to a depth of 102 cm (40 in) or more. Cracks are more prominent in the microlows. COLE is more than 0.07. The range in characteristics represents 50 percent or more of each pedon unless otherwise stated.
A horizons:
Hue: 7.5YR or 10YR
Value: 2 to 4, 3 to 5 dry
Chroma: 1 or 2
Texture: clay
Redox accumulations: masses of iron-manganese and oxidized rhizospheres range from few to many
Redox depletions: iron depletions on faces of peds and in root pores range from none to common
Reaction: slightly alkaline to moderately alkaline
Effervescence: none or slight
Bw horizon:
Hue: N to 2.5Y
Value: 3 to 6, 4 to 7 dry
Chroma: 1 or less
Note: After periods of prolonged saturation some pedons have neutral colors with moist color value of 4 to 6
Texture: clay
Redox accumulations: masses of iron-manganese and oxidized rhizospheres range from few to many
Redox depletions: iron depletions on faces of peds and in root pores range from none to common
Reaction: slightly alkaline to moderately alkaline
Effervescence: none or slight
Bss horizon:
Hue: N to 2.5Y
Value: 4 to 6, 5 to 7 dry
Chroma: 2 or less
Note: After periods of prolonged saturation some pedons have neutral colors with moist color value of 4 to 6
Texture: clay
Redox accumulations: masses of iron-manganese and oxidized rhizospheres range from few to many
Redox depletions: iron depletions on faces of peds and in root pores range from none to common
Effervescence: none or slight
Reaction: slightly alkaline to moderately alkaline
Bkss horizon: (where present)
Hue: 10YR or 2.5Y
Value: 4 to 7, 5 to 8 dry
Chroma: 1 or 2
Texture: clay
Redox accumulations: masses of iron-manganese and oxidized rhizospheres range from none to few
Calcium carbonate equivalent: less than 15 percent.
Visible calcium carbonate: 3 to 10 percent as films, threads, masses, and nodules.
Effervescence: strong or violent
Reaction: moderately alkaline
COMPETING SERIES: This is the
Eastall (OK),
Randall (TX),
Rosston (OK), and
Ustibuck (OK) series. Similar soils are the
Chapel, McLean,
Lazbuddie,
Lockney, and
Sparenberg series.
Eastall,
Rosston, and
Ustibuck series: are in a slightly moister climate and formed in sediments derived from mixed sources.
Randall series: has 50 to 60 percent clay in the particle-size control section.
Chapel, McLean, and
Sparenberg series: do not have aquic conditions and have cracks that remain open for less than 150 cumulative days during most years.
Lazbuddie and
Lockney series: do not have aquic conditions and have cracks that remain open for 150 to 210 cumulative days during most years.
GEOGRAPHIC SETTING:
Parent material: clayey lacustrine sediments derived from Blackwater Draw Formation of Pleistocene age.
Landform: on the floor of playa basins 1.5 to 15 m (5 to 50 ft) below the surrounding plain and range in size from 5 acres to more than 50 acres.
Slopes: range from 0 to 1 percent.
Mean annual air temperature: 14 to 17 degrees C (58 to 63 degrees F).
Mean annual precipitation: 381 to 508 mm (15 to 20 in).
Frost-free period: 205 to 220 days.
Elevation: 823 to 1,646 m (2,700 to 5,400 ft).
Thornthwaite annual P-E Index Values: 24 to 32.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the similar
Sparenberg series and
Acuff,
Amarillo,
Arch,
Drake,
Estacado,
Midessa,
Pep,
Portales, and
Posey series. These soils do not have aquic conditions.
Sparenberg soils are on similar landscape positions.
Acuff,
Amarillo,
Estacado and
Posey soils are on surrounding plains and have an argillic horizon.
Arch,
Drake,
Midessa,
Portales, and
Pep soils are on slightly higher landscape positions and have 18 to 35 percent clay in the particle-size control section.
DRAINAGE AND PERMEABILITY: Poorly drained. Very slow permeability. Runoff is negligible. These soils are frequently ponded for long or very long periods in most years.
USE AND VEGETATION: Used mainly for livestock grazing and wildlife habitat. Vegetation varies according to amount of water available. It includes knotgrass, bur ragweed, sedges, spike rushes, smartweed, saltmarsh aster, curly dock, frog-fruit, and bushy knotweed. In areas of standing water longbarb arrowhead, soft-stem bulrush, and southern cattail may be present. Around the margins, where ponding occurs for shorter periods the woody vegetation includes western willow and some saltcedar. This soil has been correlated to the Playa (077CY027TX) range site in MLRA-77.
DISTRIBUTION AND EXTENT: Southern High Plains, Southern Part (MLRA 77C in LRR H) of west Texas and eastern New Mexico. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: MLRA-77 Soil Survey; Lynn County, Texas; 1995
REMARKS: Ranco soils were formerly included with the Randall series. These soils have aquic conditions between 41 to 51 cm (16 and 20 in) of the soil surface in most years.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: 0 to 64 cm. (A and Bw horizons)
Cambic horizon: 23 to 64 cm. (Bw horizon)
Aquic conditions: 0 to 89 cm (0 to 35 in). (A, Bw, and Bss1 horizons) periodic saturation and reduction, redox features.
Redox concentrations: 0 to 35 cm (0 to 35 in). (A , Bw, Bss1 horizons) zone of apparent accumulation of Fe-Mn oxides.
Vertic feature: 64 to 229 cm (25 to 90 in). (Bss horizons) wedge-shaped aggregates and slickensides. Deep wide cracks that open for 90 or more cumulative days in most years.
ADDITIONAL DATA: NSSL on pedon (S96TX-305-003) from Lynn County, Texas.
Taxonomic version: Keys to Soil Taxonomy, Eleventh Edition, 2010.
National Cooperative Soil Survey
U.S.A.