The Southern High Plains area includes portions of Colorado, Kansas,
Oklahoma, New Mexico, and Texas for a total of 29.8 million acres (NRCS,
1996). This document will be restricted to those soils found in the southern
region states of Oklahoma, which has 3.1 million acres, and Texas, which
has 23.8 million acres. There are approximately 1 million acres of this
major land resource area (MLRA) in Kansas and New Mexico with a very small
amount of acreage in Colorado. The soils of MLRA 77 are some of the driest
within the southern region and the land is used primarily for farming and
ranching. Irrigation began in earnest in the 1950s and increased until
the early 1970s. Since that time, irrigated acres have declined due to
the cost of pumping water from the aquifer. The Southern High Plains grows
corn, wheat, cotton, grain sorghum, and has some rangeland. The southern
portion of the area is the largest single cotton-production region in the
Elevation and Topography
The Southern High Plains are found on the flat, steppe land east of
the Rocky Mountain foothills. Because of the broad expanse of this flat
plateau, this area was one of the first highly mechanized agricultural
regions in the world. The plains gently slope from the northwest to the
southeast and range in elevation from 800 to 2000 m above sea level. Deep
sands are located in the western portions of the MLRA with occasional dunes
running eastward. Slopes are gentle and often less than 3%. Steeper slopes
are found along the Brazos, Canadian, and Cimarron rivers. A shaded relief
map for this MLRA may be accessed through the internet at (http://fermi.jhuapl.edu/states/states.html).
The area has a semiarid to subhumid climate. Precipitation ranges from
16 to 20 inches annually and occurs mainly from late May through early
September. October through April are dry months with occasional snow events.
As with any semiarid climatic region, precipitation events are extremely
variable and annual amounts differ widely from year to year. Precipitation
places most of these soils within the ustic moisture regime. The MLRA is
separated into the thermic temperature regime south of the Canadian river
and mesic temperature regime north of the Canadian River. Average temperature
ranges from 55°F in the north to 63°F in the south. The areas north
of the Canadian River have minimum January temperatures in the 18 to 22°F
range while the areas below the Canadian River are 18 to 28°F. Maximum
July temperatures north of the Canadian range from 92 to 95°F while
those south of the Canadian River range from 92 to 96°F. As with the
original description of the climatic regimes, this river generally separates
the cotton (Gossypium hirsutum L.) growing areas in the south from
the non-cotton growing areas north. Average freeze-free periods range from
130 days in the north to 220 days in the south.
MLRA 77 is part of the Great Plains Province and consists of High Plains
and Plains Border areas (Buol, 1973). STATSGO soils of this MLRA are provided
in Fig. 1. It is bordered on the southeast by the Coastal Plains Providence
and the west by the Pecos valley. It is formed from eolian sediments which
become finer and darker towards the northeast (Seitlheko, 1975). Most of
the soils are deep, fine and medium textured Ustolls and Ustalfs (USDA,
Soils north of the Canadian River are mesic while those south are thermic.
Paleustolls, Argiustolls, Paleustalfs, and Hapustolls are found on the
uplands. Calciustolls and Paleustolls dominate the ridges with shallow
Calciorthhids, Paleorthids and Torriorthents on the steep slopes of the
breaks. Haplustolls are on young valley floors with Pellusterts in the
clayey playa lake basins. Paleustalfs, Haplargids, Ustipsamments, and Torripsamments
comprise the deep sandy soils in the southwest (USDA, 1981).
Of the approximately 27 million acres of this MLRA in Oklahoma and Texas,
those soils that have areal extent of more than 10,000 acres fall into
six orders—Alfisols, Aridisols, Entisols, Inceptisols, Mollisols, and Vertisols.
These soils (>10,000 acres) are listed by soil subgroup in Table
Most of the predominant soils are in the order Alfisols or Mollisols.
The other orders are represented by fewer than three soils per subgroup.
Specific soil series descriptions may be found on the Iowa State World
Wide Web at (http://www.statlab.iastate.edu/cgi-bin/osd/osdname.cgi).
After that site is accessed, the series name may be entered for a complete
soil description. Selected physical properties for these soils are presented
in Table 2.
Within this document, we shall only discuss five of the major soils
(>10,000 acres) within this MLRA—Acuff, Amarillo, Pullman, Randall, and
Sherm. The Acuff (fine-loamy, mixed, superactive, thermic Aridic Paleustolls)
and Amarillo (fine-loamy, mixed, thermic Aridic Paleustalfs) soils are
typical of the sandy loam soils of the Southern High Plains. The Pullman
(fine, mixed, superactive, thermic, Torrertic Paleustolls) and Sherm (fine,
mixed mesic Torrertic Paleustolls) are typical of the clay loam soils of
the Southern High Plains. Pullman is thermic clay loam soil, which occurs
south of the Canadian River, while the Sherm is the mesic temperature regime
soil found north of the Canadian River. An additional predominant soil
in this MLRA that is comparable to the Pullman and Sherm is the Olton (fine,
mixed superactive, thermic Aridic Paleustolls). This soil has recently
been discussed by Unger and Pringle (1998), and will not be discussed in
detail in this document. The Randall (fine, smectitic thermic Ustic Epiaquerts),
the final soil to be discussed, forms the drainage basin for the upland
soils mentioned above. This clay-textured soil serves as the run off catchment
for the entire Southern High Plains and forms the playa basin which is
the most unique geomorphic feature of the area. Currently, the Randall
soil series is being modified with additional soil series being described.
Understanding the soil-water relations of these five soils will define
the water relations of the entire MLRA.
The distribution, importance, variability, and management
of the Acuff
soil has been discussed by Unger et al. (1993). This
soil series has been mapped as a loam, clay loam, and sandy clay loam (Table
3) and is extensively used for row crops. The Acuff series occupies
parts of 22 Southern High Plains counties in Texas and is used for both
irrigated and dryland production. This soil occupies over 950,000 acres
in Texas and ranges from 0.1 to 37% within these counties. Variability
in average infiltration rate ranges from >0.75 in. hr-1 for
loose, bulked soil with heavy residues to <0.04 in. hr-1
for severely compacted tillage pans (see Table
4). Volumetric water contents at -0.033MPa ranged from 15.2% to 27.4%
within 11 Texas pedons. The volumetric water contents for the same pedons
at -1.5MPa ranged from 8.2 to 18.8%.
profile descriptions from Unger et al. (1993) are available here.
The Amarillo series is the alfisol companion
to the Acuff Mollisol. Although the Amarillo soil is named after Amarillo,
Texas which lies in the central part of this MLRA, the soil is generally
found in the southern, sandier portion of the region. Four
soil profiles for the Amarillo series are given here. Water retention
data for these soils are given in Table 5.
The Pullman is probably one of most extensive
row cropped soils in the United States. Unger and Pringle (1981) have described
the distribution, importance, variability, and management of this soil
which covers more than 3.8 million acres in Texas. The remainder of the
area is associated with playa lake soils of which the Randall occupies
the playa floor. Pullman soils are typically thought of as clay loam textured
but have some inclusions of silty clay loam textures. The water infiltration
rates (Table 6) were generally higher
in the southwest portion of the region than in the northern part. The cumulative
infiltration for 10 minutes ranged from 0.80 to 1.64 inches with a mean
of 1.27 inches and a standard deviation of 0.28 inches. Twenty hour cumulative
infiltration ranged from 3.18 to 4.9 inches with a mean value of 4.33 inches
with a standard deviation of 0.58 inches (see Table
7). Calculated volumetric water contents (Unger and Pringle, 1981)
ranged from 21.1% to 28.5% for -0.033MPa in the A horizons. Similar calculated
values for the -1.5MPa potentials ranged from 13.3 to 18.7%. Detailed
profile descriptions for the Pullman soil are presented here.
Prior to the adoption of Soil Taxonomy (USDA, 1975),
the Pullman soil discussed above incorporated the Sherm soil which
will now be discussed. The taxonomic distinction between these soils is
found at the family level in which the Sherm is a "mesic" soil while the
Pullman is "thermic." Unger and Pringle (1986) evaluated seven Sherm pedons
under various tillage conditions (Tables 8
and 9). They reported 10 minute cumulative infiltration values to range
from 0.38 to 2.04 inches . The mean for these infiltrations was 1.13 inches
with a standard deviation of 0.42 inches. The least value (0.38) occurred
in a wheel track furrow which had a thick crust. The greatest value (2.04
in.) occurred in loose surface following sweep tillage. Twenty hour cumulative
infiltrations ranged from 1.41 to 15.66 inches with a mean of 6.64 and
a standard deviation of 4.35 inches. The least infiltration (1.41 in.)
occurred under a loose surface which had a tillage pan at 2 inches below
the surface. The greatest infiltration occurred preplant with a loose surface
and no crusting conditions. Calculated -0.033MPa water contents ranged
from 29.5 to 40.7%. The median value was 36.1% with a mean value of 35.2%
with a standard deviation of 4.26. Calculated -1.5MPa values ranged from
19.2 to 28.2%. Median value was 23.1% with a mean value of 23.5% and a
standard deviation of 3.3. Detailed profile
descriptions for the Sherm soil are presented here.
The final soil of this MLRA to be discussed in
detail will be the playa lake soils comprised of the Randall clay.
Playas, as depressional areas that create ephemeral lakes, are the most
interesting topographic feature of this MLRA. There are approximately 27,000
playas on the Southern High Plains which serve as catchment basins for
runoff from the upland soils previously discussed. Most of MLRA 77 has
no rivers or streams to remove runoff waters which flow to the internally
drained playas. Playa lakes range in surface area from 0.5 to 25 ha and
drain an area of approximately 300 ha. Prior to 1985, all playas were classified
as Randall except those playas in the mesic temperature regime, which were
classified as Ness (Fine, smectitic, mesic Udic Pellusterts). Playas that
were found under more arid conditions were classified as Lipan (Fine, smectitic
thermic Chromic Haplusterts).
Randall soil profiles are presented here (Evans, 1990; Paetzold, 1972).
Water retention data from two Randall soil profiles at several depths are
presented in Table 10.
Historically, the playas have been thought to lose most of their accumulated
water back to the atmosphere by evaporation (Reddell, 1965). Recent investigations
(Zartman et al., 1994) have revealed large quantities of recharge occurring
from playa lakes. They evaluated three playa lakes at different elevations
with in each lake. Each of the three polypedons was divided further into
one of three classes of elevations from which 14 pedons were evaluated
for infiltration. One minute and greater than 72 hour infiltration rates
for the high, intermediate, and low elevations within the playas are given
in Table 11.
While the variation of infiltration rates of the data set are quite
large, it must be remembered what the data are portraying. This Vertisol
is beset with abundant, deep cracks when it’s dry. The thesis from which
the data were obtained (Evans, 1990), evaluated the bimodal cracking pattern
of the Randall soil. The variability of the data were similar to that presented
by Talsma and van der Lelij (1976) in an Australian vertisol. Infiltration
variability is not only within playas, but also among playas. Unpublished
data (Zartman, 1997) shows greater infiltration rates for the Randall soil
in the Southern portions of this MLRA (Lubbock County) than in the Northern
portion (Carson County). Figures 2 and 3 present Stage I and Stage III
infiltration using double ring infiltrometers. Both Figs. 2 and 3 show
greater infiltration rates in the southern playas as compared to the northern
The Randall soil and its presence in MLRA 77 are being reevaluated.
At one time all depressions in the Southern High Plains portion of MLRA
77 were classified as playas. The data presented in Figs. 1 and 2 above
indicate that there are differences within the Randall series. As this
document is written the Randall soil is being divided into 11 different
soil series (Mr. T. Craig Byrd, NRCS, 1998). There are five depressional
soils originally mapped as Randall, but lie outside of the current concept
of playa lakes. Some of those soils that occupied the depressional areas
of the landscape, while mapped as Randall, were not clay textured soils.
Current soil survey reports have some sandy loam and clay loam soils mapped
as the Randall. The Lamesa soil (fine-loamy, mixed, superactive, thermic
Aeric Endoaqualfs) has aquic conditions at some times in most years, but
has a sandy clay surface texture. The Lenorah fine sandy loam(fine-loamy,
mixed, active calcareous thermic, Aeric Halaquepts) has a calcic horizon
within 40 inches of the surface. The Cedarlake sandy clay loam (fine- loamy,
mixed, superactive calcareous, thermic Typic Halaquepts) are found on the
basins above the salt lakes of the region. The Segraves fine sandy loam
fine-loamy, mixed, superactive, Typic Plaeustalfs) are playa-like depressions
without the aquic conditions of a Randall. Lofton clay loam (fine, smectitic,
thermic Vertic Argiustolls) is found on a slightly higher landscape position
than the Randall.
Other soils are being separated from the Randall series due to the clay
content or moisture conditions. One competing series is the Ranco (fine,
smectitic, thermic, Ustic Epiaquerts). This soil is differentiated from
the Randall by having 50% or less clay in the control section. Similar
soils to be separated from the Randall are the Chapel (fine, smectitic,
thermic Udic Calciusterts), Sparenberg (fine, smectitic thermic Udic Haplusterts),
and McLean (fine, smectitic, thermic Udic Haplusterts). These three soils
do not have aquic moisture conditions and have cracks that remain open
for less than 150 cumulative days during most years. Other similar series
are the Lazbuddie (fine, smectitic, thermic Typic Haplusterts) and Lockney
(fine, smetitic, thermic Typic Haplusterts) that do not have aquic conditions
and have cracks that remain open for 150 to 210 cumulative days during
The soils of MLRA 77 are some of the most extensively farmed soils
in the world. The steppe features of this area were those that allowed
for some of the first large scale mechanization, which are very common
in agriculture today. This MLRA differs from many of the rest of the MLRAs
of the southern region due to the vast expanse of arable lands. While the
precipitation received is less than most southern MLRAs, the economies
of scale make this region a very agriculturally productive one.
Bryant, R.B. 1977. A comparison of physical and chemical properties
of selected irrigated, dryland and native range Texas High Plains soils.
M.S. Thesis. Texas Tech Univ., Lubbock.
Buol, S.W. 1973. Soils of the Southern States and Puerto Rico. Southern
Cooperative Series Bull. 174.
Evans, P.W. 1990. Determining the bimodal infiltration patterns in three
playa lakes. M.S. Thesis. Texas Tech Univ., Lub-bock.
NRCS. 1996. Personal contact with Mr. W. Mike Risinger, Temple, Texas.
NRCS. 1998. Personal contact with Mr. T. Craig Byrd, Lubbock, Texas.
Layla, S.T. 1982. Influence of soil separates and mineralogy on soil-water
content as affected by Super Slurper. M.S. Thesis. Texas Tech Univ., Lubbock.
Olson, C.G. (ed.) 1996. Bibliography of MLRA 77: A reference guide to
publications of the Southern High Plains. p. 132. Ver 3.0. National Soil
Survey Center, USDA-Natural Resources Conservation Service, Lincoln, Nebraska.
Paetzold, R.F. 1972. Water movement in selected Texas High Plains soils.
M.S. Thesis. Texas Tech Univ., Lubbock.
Reddell, D.L. 1965. Water resources of playa lakes. Cross Section 12(3):1.
Seitlheko, E.M. 1975. Studies of mean particle size and mineralogy of
sands along selected transects on the Llano Estacado. M.S. Thesis. Texas
Tech Univ., Lubbock.
Talsma, T. and A.van der Lelij. 1976. Infiltration and water movement
in an in situ swelling soil during prolonged ponding. Aust. J. Soil
Unger, P.W. 1975. Relationship between water retention, texture, density,
and organic matter content of west and south central Texas soils. MP-11920.
Texas Ag. Expt. Sta., College Station.
Unger, P.W. and F.B. Pringle. 1981. Pullman soils: Distribution, Importance,
variability, and management. Texas Agric. Exp. Stn. Bull. No. 1372.
Unger, P.W. and F.B. Pringle. 1986. Sherm soils: Distribution, Importance,
variability, and management. Texas Agric. Exp. Stn. Bull. No. 1513.
Unger, P.W. and F.B. Pringle. 1998. Olton soils: Distribution, Importance,
variability, and management. Texas Agric. Exp. Stn. Bull. No. 1727.
Unger, P.W., F.B. Pringle, and D.A. Blackstock. 1993. Acuff soils: Distribution,
Importance, variability, and management. Texas Agric. Exp. Stn. Bull. No.
USDA. 1981. Land resource regions and major land resource areas of the
United States. Ag. Hndbk. #296. Washington, DC.
USDA. 1975. Soil Taxonomy. Ag. Handbook. #436. Washington, DC.
Zartman, R.E, P.W. Evans and R.H. Ramsey. 1994. Playa lakes on the Southern
High Plains in Texas: Reevaluating infiltration. J. Soil Water Conserv.
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Electronic document prepared by:
D.L. Nofziger, Oklahoma State University
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