deann r. presley, m.d. ransom, william a. wehmueller, and wes … · 2020-01-13 · all pedons were...
TRANSCRIPT
1SOIL SURVEYHORIZONS
Upland soils of east-central Kansas exhibit a long and complex
genesis. They have multiple parent materials formed under tall-
grass prairie in an area that is transitional between udic and ustic
moisture regimes.
The Bluestem Hills Major Land Resource Area (MLRA 76), also com-
monly referred to as the Flint Hills region, is approximately 19,585 km2
(7555 miles2) in size (Fig. 1). The bedrock is Permian-aged shale and
limestone. About 70% of the area is in rangeland used for grazing cattle.
Twenty percent of the area is cropland, which is located on the uplands
and in river valleys. Tallgrass prairie is the native vegetation and includes
big bluestem (Andropogon gerardi Vitman), Indiangrass [Sorghastrum
nutans (L.) Nash], and switchgrass (Panicum virgatum L.). The annual
precipitation is 785 to 965 mm (USDA-NRCS, 2006).
Small areas (usually »10 by 10 m in diameter) of short, sparse, or low-quality range-land vegetation are commonly present within the map units of soil series mapped on upland interfluves or in upland depressions of the Bluestem Hills Major Land Resource Area (MLRA 76). Because of the poor vegetation, soil scientists commonly assumed that these areas result from Na+, so they were mapped as Natrustolls. But, upon laboratory characterization, few pedons met the natric diagnostic horizon criteria. Therefore, the objectives of this study were to examine the morphology and Na+ content of several small areas of sparse, poor vegetation in native grass uplands of the Bluestem Hills Major Land Resource Area to determine if these areas meet the natric diagnostic horizon criteria and examine profile or landscape features that would make detecting the presence of a natric diagnostic horizon more predictable. Eleven pedons were investigated, sampled, and characterized in the laboratory for particle size, exchangeable Na+ percentage (ESP), and other characteristics. Two of the 11 pedons met the natric diagnostic horizon criteria, and greater maximum profile ESP values were observed within the shallowest pedons (i.e., those < 1 m to bedrock; Pr > F 0.2533). Elevated ESP values ranging from »5 to 14% ESP were observed for eight of the other nine pedons. The ESP values were greatest in the horizons with the finest textures. The presence of short, sparse, poor-quality rangeland does not appear to be an appropriate visual cue for mapping soils that contain natric hori-zons but is an indicator of elevated ESP levels. Therefore, creation of either a paranatric diagnostic horizon or a Natric Argiustolls subgroup for soils with moderate levels of Na+ might be a suitable solution useful for soil scientists in the field.
D.R. Presley ([email protected]) and M.D. Ransom, Dep. of Agron., Throckmorton Hall, Kansas State Univ., Manhattan, KS, 66506-5501; W.A. Wehmueller, USDA-NRCS, 760 South Broadway Salina, KS, 67401; W. Tuttle, USDA-NRCS/NSCC, Federal Building, Room G-08, 207 West Main Street, Box 60, Wilkesboro, NC, 28697. Contrib. 10-348-J, Kansas Agric. Exp. Stn. Published in Soil Surv. Horiz. 51:95–101 (2011).
Sodium Accumulation in Sparsely Vegetated Areas of Native Grassland in Kansas: A Potential Need for a Paranatric Diagnostic HorizonDeAnn R. Presley, M.D. Ransom, William A. Wehmueller, and Wes Tuttle
Fig. 1. Study area and sampling locations within the Bluestem Hills Major Land Resource Area (MLRA 76) in Kansas. Although Pedon 7 lies outside this MLRA, all soil forming factors are consistent with those of the other pedons sampled in this study.
2 S O I L S U R V E Y H O R I Z O N S
errezia dracunculoides (DC.) Blake], while sedges (Cyperaceae family)
were associated with closed upland depressions. Broom snakeweed
is usually associated with overgrazing or disturbance (Owensby, 2004),
and sedges are frequently found in wet, upland prairies (Ladd, 1995).
The closed upland depressions are usually wet in the spring and retain
water after precipitation events. These areas were associated with flat
interfluves or closed upland depressions, and are colloquially referred
to in the region as relict bison wallows or, less frequently, greater prairie
chicken booming grounds.
The genesis of relict bison wallows is often attributed to the soil compac-
tion resulting from bison wallowing or rolling in an attempt to relieve skin
irritation from insects (Darton, 1905; McMillan et al., 2000; Trager et al.,
2004). Other researchers have concluded that these upland depressions
are natural landscape features formed through pedogenesis (Coppedge
et al., 1999) and possibly exacerbated in size and depth by subsequent
use by bison (Frye, 1950). Coppedge et al. (1999) observed the behavior
of bison and the utilization of relict upland depressions vs. the formation
of new dust wallows in late fall. Coppedge et al. (1999) cited the follow-
ing reasons for rejecting a sole bison-formation theory. First, upland
soil depressions contained Na+, whereas newly formed bison wallows
did not. Second, newly formed wallows were revegetated within 3 yr of
abandonment by the bison.
According to Soil Taxonomy (Soil Survey Staff, 1999), an argillic horizon
must meet the following structural and chemical criteria to be classified
as a special kind of argillic horizon, called a natric horizon:
Structural requirement: The horizon has to have columnar or prismatic
structure, or can have blocky structure as long as there is evidence of
eluvial materials, namely uncoated silt or sand grains.
Chemical requirement: The horizon has to have an exchangeable sodium
percentage (ESP) of ³15% or sodium absorption ratio (SAR) of ³13
within 40 cm of the upper boundary of the argillic horizon. Alternatively,
it can also meet the chemical requirement by having more exchangeable
magnesium (Mg2+) and sodium (Na+) than calcium (Ca2+) and extract-
able acidity (H+) within 40 cm of the upper boundary as long as there is
a horizon within 200 cm of the soil surface that meets the first chemical
requirement (ESP ³ 15% or SAR ³ 13).
In Kansas, soil scientists mapped large areas of these Na+-contain-
ing soils dotted with bison wallows as either the Dwight series or the
Dwight series in consociation or complex with other series such as Irwin
(Table 2). Also, an inclusion or spot symbol was used in some counties
to denote areas too small to delineate at the second-order soil survey
level. However, on laboratory characterization, many of these soils did
not meet the natric diagnostic horizon criteria and were later correlated
to either Konza or Irwin as those counties were updated (William Wehm-
ueller, personal communication, 2005). At the present time, 114,711 ha
(283,456 acres) of Dwight are still mapped in Kansas as either series, in
consociation, or in complexes (William Wehmueller, personal communi-
cation, 2009). This value is adjusted to reflect the estimated component
percentage of the map unit (Table 2).
Because of the poor vegetation, soil scientists commonly assumed (and
still do) that these areas result from Na+, so these areas were mapped
as Natrustolls (Dwight series), in complexes with the Dwight series, or as
Common upland soil series mapped in MLRA 76 include the Irwin,
Konza, and Dwight series, which are mapped adjacently on inter-
fluves and benches. The complete family classifications are given in
Table 1. Parent materials for these series were historically described as
clayey sediments, such as old alluvium, colluvium, loess, and residuum,
whereas recent investigations have described a more complicated and
polygenetic suite of parent materials for the modern soil and underlying
paleosols (Glaze, 1998; Presley, 2007; Presley et al., 2010; Wehmuel-
ler, 1996). While mapping soils in the Bluestem Hills, Wehmueller (1996)
found a soil that did not meet the criteria for either the Dwight series
or the Irwin series, and as a result of that study the Konza series was
established in 1991. Also working in this region of Kansas, Glaze (1998)
studied three polygenetic loess-paleosol pedons to determine the pro-
cess of Na+ accumulation and genesis for the Konza series. Glaze
concluded that Na+ dissolved in soil water reached a slowly permeable
(clayey) layer in a soil profile and that the Na+ caused clay dispersion,
which changed the pore-size distribution and thus made the layer even
less permeable to water. As pore size becomes smaller and perme-
ability becomes slower, even more clay and Na+ could accumulate in
this horizon, eventually leading to the formation of a layer meeting the
natric horizon exchangeable Na+ percentage (ESP) or Na+ absorption
ratio (SAR) requirement. Therefore, the slowly permeable layer pres-
ent in soils observed by Glaze (1998) facilitated the formation of a natric
horizon. White (1999) concluded that horizons in clayey soils of South
Dakota start out as argillic horizons, accumulate Na+ and clay with time
and mineral weathering, and eventually become natric horizons. Thus,
argillic and natric horizons can be hard to distinguish from each other,
especially when they are in the transition process.
The Irwin, Konza, Dwight, and Ladysmith series are similar in that all
are primarily mapped on upland positions in MLRA 76. Also, all of these
soils are Mollisols and contain an argillic horizon, and all have a “fine”
family particle-size class because they contain more than 35% clay in
the upper 50 cm of the argillic horizon. There are also many differences
between these series. All of the series except for Irwin have smectitic
mineralogy (Table 1). Dwight and Konza are known to contain a zone of
significant Na+ accumulation. Dwight soils contain a natric horizon, but
the Na+ accumulation in Konza is either not great enough to classify as
natric or occurs too deep in the soil profile to classify as natric (Glaze,
1998). Irwin and Ladysmith soils often contain a zone of Na+ accumula-
tion in the soil profile, but to a lesser degree than the Dwight series.
In a study of the morphology, genesis, and distribution of these four soil
series, Presley (2007) routinely observed small areas (usually »10 by
10 m in diameter) of short, sparse, or low-quality rangeland vegetation
in the map units of all four of these series. Compared with the sur-
rounding vegetation, the vegetation in these areas was approximately
one-half as tall and less dense (i.e., the soil was often visible between
the range plants). One range plant commonly observed in these areas
on flat or gently sloping (<3%) interfluves was broom snakeweed [Guti-
Table 1. Family classification of the soil series of interest in MLRA 76 in Kansas.
Soil series Family classificationIrwin Fine, mixed, superactive mesic Pachic ArgiustollsLadysmith Fine, smectitic, mesic Udertic ArgiustollsDwight Fine, smectitic, mesic Typic NatrustollsKonza Fine, smectitic, mesic Udertic Paleustolls
3S p r i n g 2 0 1 1
soil probe. Pedons were sampled to the depth of refusal, usually by a
lithic or paralithic contact. All pedons were described using the Field
Book for Describing and Sampling Soils (Schoeneberger et al., 2002).
Bulk samples were collected from the horizons of all pedons for lab-
oratory characterization, and thick horizons (>20 cm) were split and
subsampled.
Air-dry bulk samples were crushed with a wooden rolling pin and passed
through a no. 10 sieve with 2-mm square openings. Soil pH was deter-
mined in a 1:1 soil/water suspension and in a 1:2 0.01 M CaCl2 solution
using Method 8C1F of the Soil Survey Laboratory Methods Manual (Soil
Survey Laboratory Staff, 1996). Total carbon was determined using a
high-frequency induction furnace (Leco Model CNS-2000, St. Joseph,
MI) following the procedure of Tabatabai and Bremner (1970).
Particle-size distribution was determined using a modification of the
pipet method of Kilmer and Alexander (1949) with the following modifi-
cations. All samples that contained >1.4% total C were pretreated with
30% hydrogen peroxide for better dispersion. Ten grams of <2-mm soil
was weighed into 450-mL square sedimentation bottles. To each bottle,
a 10-mL aliquot of dispersing agent was added, which contained 35.7 g
of sodium hexametaphosphate [(Na(PO3)6] and 7.9 g of sodium carbon-
ate (Na2CO3) per liter of solution. The bottles were filled approximately
inclusions within other series. Therefore, the objective of this study was
to examine the morphology and Na+ content of several “best examples”
of these small areas of sparse, poor vegetation in native grass uplands
of the Bluestem Hills MLRA to determine if these areas meet the natric
diagnostic horizon criteria. We also attempted to determine if these
areas have any common features with respect to profile or landscape
features that would make detecting the presence of a natric diagnostic
horizon more predictable.
Materials and MethodsThe study area is located in the Bluestem Hills MLRA with sites in Morris,
Chase, and Butler counties in Kansas (Fig. 1). Seventy-two percent of the
Dwight acres mapped in Kansas occur in these three counties, and the
remainder is mapped in 12 additional counties that lie all or partly within
MLRA 76 (Table 2). Land use for all sampled pedons is native grass-
land used for grazing cattle. All pedons were sampled on interfluves of
uplands, and the microtopographic features are given in Table 3.
Eleven pedons were selected from a larger study completed by Presley
(2007). These 11 soil profiles represent the best examples of bison wal-
lows observed on landscapes in or consistent with the Bluestem Hills
MLRA. Soil pedons were investigated using a hydraulic, truck-mounted
Table 2. All Dwight map units, including component percentage, acres, kind, and counties where mapped in MLRA 76 in Kansas.
Map unit name Component Map unit area Map unit kindCountyname†
TotalDwight‡
CountyDwight§ Rank¶
% ha ————————— ha —————————Dwight silt loam, 0 to 1% slopes 90 39596 Consociation Butler 35636 53649 1Dwight soils, 1 to 3% slopes, eroded 85 1567 Consociation Butler 1332Labette–Dwight complex, 0 to 3% slopes 40 41701 Complex Butler 16680Labette–Dwight complex, 0 to 3% slopes 40 25978 Complex Morris 10391 16455 2Dwight silt loam, 1 to 3% slopes 85 7134 Consociation Morris 6064Dwight silt loam, 0 to 1% slopes 90 255 Consociation Chase 230 12913 3Dwight silt loam, 1 to 3% slopes 85 8149 Consociation Chase 6926Labette–Dwight complex, 0 to 3% slopes 41 11789 Complex Chase 4833Zaar–Dwight complex, 1 to 3% slopes 45 2053 Complex Chase 924Dwight silt loam, 0 to 1% slopes 90 3809 Consociation Cowley 3428 7973 4Labette–Dwight complex, 0 to 3% slopes 35 12985 Complex Cowley 4545Dwight–Irwin complex, 1 to 3% slopes 45 6822 Complex Riley 3070 5515 5Dwight–Irwin complex, 1 to 3% slopes, eroded 45 5434 Complex Riley 2445Labette–Dwight complex, 0 to 3% slopes 30 12584 Complex Greenwood 3775 5343 6Dwight silt loam, 0 to 1% slopes 90 1742 Consociation Greenwood 1568Labette–Dwight complex, 0 to 3% slopes 35 5474 Complex Marion 1916 3188 7Dwight silt loam, 0 to 1% slopes 90 1413 Consociation Marion 1272Dwight silt loam, 0 to 1% slopes 90 450 Consociation Elk 405 2200 8Eram–Dwight silt loams, 1 to 4% slopes 30 735 Complex Elk 221Labette–Dwight complex, 0 to 3% slopes 35 4500 Complex Elk 1575Labette–Dwight complex, 0 to 3% slopes 35 5583 Complex Lyon 1954 1954 9Dwight silty clay loam, 0 to 1% slopes 97 167 Consociation Shawnee 162 1500 10Dwight silty clay loam, 1 to 3% slopes 85 827 Consociation Shawnee 703Dwight–Martin silty clay loams, 1 to 3% slopes 60 1025 Complex Shawnee 615Elmont–Dwight silty clay loams, 3 to 7% slopes,
eroded25 80 Complex Shawnee 20
Dwight silt loam, 0 to 1% slopes 98 1238 Consociation Woodson 1214 1214 11Labette–Dwight complex, 0 to 3% slopes 35 136 Complex Chautauqua 48 1116 12Martin–Dwight silty clay loams, 1 to 3% slopes 15 5664 Complex Chautauqua 850Dennis–Dwight silt loams, 1 to 5% slopes 23 951 Complex Chautauqua 219Dwight–Martin silty clay loams, 1 to 3% slopes 60 2 Complex Osage 1 1066 13Dwight silty clay loam, 1 to 3% slopes 85 6 Consociation Osage 5Dwight silt loam, 1 to 3% slopes 90 1178 Consociation Osage 1060Dennis–Dwight silt loams, 1 to 5% slopes 25 2552 Complex Wilson 638 638 14Summit–Dwight complex, 1 to 3% slopes 20 371 Complex Coffey 74 74 15
Sum (ha) 114,799
†All counties are in Kansas.‡ Calculated by multiplying the component percentage by the total acres for that map unit.§ Calculated by multiplying the component percentage by the total acres for that map unit and summing for the county.¶ Ranked according to the total amount of Dwight series mapped within the county.
4 S O I L S U R V E Y H O R I Z O N S
For the EM-38 survey, two parallel lines defined the eastern and western
boundaries of the survey site. Each line was 36 m long. The lines were
spaced approximately 36 m apart. Each survey traverse line (east to
west/west to east direction) had a 2-m interval spacing. An electromag-
netic induction survey was completed by walking at a fairly uniform pace
between similarly numbered survey lines on the opposing set of parallel
lines in a back and forth pattern. The EM-38M was carried at a height of
approximately 7.5 cm above the surface and was operated in the contin-
uous mode with measurements recorded at a 1-s interval. The meter was
carried in the vertical dipole orientation while measurements of apparent
conductivity were geo-referenced. Apparent conductivity was measured
in millisiemens per meter (mS/m).
Results and DiscussionSodium Accumulation, Landscape
Position, and Appearance of VegetationPedon sampling locations were selected on the basis of the presence of
an upland depression or because of the short, sparse appearance of the
native prairie vegetation. Site data and field notes regarding vegetation
are given in Table 3. All Bt horizons met the criteria for argillic horizons
(i.e., contained oriented clay coatings on ped faces; data not shown). All
11 pedons contained one or more paleosols and are considered both
polygenetic and welded (Presley et al., 2010). For the sake of brevity,
Table 4 contains morphological and laboratory characterization data by
horizon for 4 the 11 study pedons, but data for all 11 pedons are available
in Presley (2007). The sites are generally numbered from north to south
within MLRA 76. All sites occur on upland interfluves.
The hillslope profile positions indicated in Table 3 are intended to
describe the microtopography of the complexly sloping upland land-
scape. Slope percentages ranged from 0 to 3%, but the slope was £2%
for most pedons. Five of the 11 sites were sampled near the center of
upland depressions, and the slope was described as 0%. The soil series
name indicated in Table 3 reflects the name of the map unit in which the
pedon was sampled.
Sites 1 and 2 were sampled in a native pasture in northern Morris
County, Kansas. Site 1 was described on a backslope with 2% slope;
however, the presence of short grass and many surface cracks was the
reason the location was chosen for sampling. The ESP throughout the
argillic horizon was »10, which is too low for the natric diagnostic hori-
half full with distilled water and capped. The bottles were shaken over-
night on a horizontal reciprocating shaker at 120 oscillations per minute.
The bottles were brought to a final solution weight of 390 g (370 g of
distilled water, 10 g of soil, and 10 g of the dispersing solution). The tem-
perature of the solution was measured to determine the time required for
sedimentation, which were calculated based on Stokes’ Law:
( )=
- 2p 1
18nht
g s s D
where t is sedimentation time in seconds, n is viscosity of water in g cm−1
s−1, h is depth of fall in cm, sp − s1 is the differential specific gravity (par-
ticle relative to liquid in g cm−3), and D is particle diameter in centimeters.
Each sample was stirred with an electric mixer for 20 s. After the first
sample of the run was stirred, a timer was set and all samples were
stirred at 1 min intervals. Samples were pipetted at the calculated times
with a 6 mL pipet for the <20-, <5-, and <2-mm fractions. The <20-mm
fraction was pipetted 8 cm from the top of the suspension, and the <5-
and <2-mm fractions were pipetted at 5 cm. Sample aliquots were placed
in preweighed ceramic crucibles and dried in an oven at 105°C over-
night. Samples were placed in a dessicator to cool before being weighed
to four decimal places. The ESP was determined per Method 5A3a of the
Soil Survey Laboratory Methods Manual by dividing the exchangeable
Na+ by the sum of the NH4OAc-extractable bases (Soil Survey Labora-
tory Staff, 1996).
At Site 4, an electromagnetic induction (EMI) tool, the EM-38 manu-
factured by Geonics Ltd. (Mississauga, Canada), was used to examine
potential differences in apparent electrical conductivity of the site. Elec-
tromagnetic induction uses electromagnetic energy to measure the
apparent conductivity of earthen materials and is a weighted, average
conductivity measurement for a column of earthen materials to a specific
depth (Greenhouse and Slaine, 1983). Variations in apparent conduc-
tivity are caused by changes in the electrical conductivity of earthen
materials. The apparent conductivity of soils increases with increased
soluble salts, clay, and water contents (Kachanoski et al., 1988; Rhoades
et al., 1976). In any soil landscape, variations in one or more of these fac-
tors may dominate the EMI response. Some soil properties and soils can
be inferred or predicted with EMI, provided one is cognizant of changes
in parent materials, topography, drainage, and vegetation.
Table 3. Site data and field notes on vegetation for soils in MLRA 76 in Kansas.
Site Pedon ID Series† Slope Hillslope position‡Subgroup
classification§ Remarks from pedon description form%
1 05KS127003 Konza 2 Backslope Typic Argiustoll Short grass, surface cracks2 05KS127005 Konza 0 Upland depression Pachic Paleustoll Sampled in upland depression, no notes on grass quality3 05KS127043 Irwin 3 Backslope Pachic Argiustoll Very short grass in pasture4 06KS127001 Irwin 0 Upland depression Typic Natrustoll Upland depression, columnar structure in Bt1, Cyperaceae family5 05KS127014 Dwight 0 Upland depression Pachic Paleustoll Depression, short, sparse vegetation, bare soil between plants, wet6 05KS127015 Dwight 2 Upland depression Typic Natrustoll Depression, short, sparse vegetation, bare soil between plants, wet7 06KS017002 Dwight 2 Backslope Pachic Argiustoll Broom snakeweed, Gutierrezia dracunculoides (DC.) Blake8 06KS015021 Ladysmith 3 Backslope Pachic Argiustoll Grass short and sparse9 06KS015006 Dwight 1 Summit Pachic Argiustoll Short grass10 06KS015007 Irwin 3 Backslope Pachic Paleustoll Short grass rings the site, grass okay where sampled11 06KS015016 Ladysmith 0 Upland depression Pachic Paleustoll Sampled in upland depression, no notes on grass quality
† The soil series name indicated in Table 3 reflects the name of the map unit in which the pedon was sampled.‡ All sites are located on upland interfluves. The hillslope profile position and slope percentage given indicate the microtopography.§ Sites 4, 6, and 7 were revised after characterization on the basis of exchangeable Na+ percentage (4, 6) and particle-size determination (7).
5S p r i n g 2 0 1 1
zon criteria. Site 2 was sampled within an upland depression, and the
ESP within the argillic horizon did not exceed 6, which is also too low to
meet the natric criteria (Table 4).
Site 3 was sampled in Morris County, Kansas, in a native grass pasture
on a 3% backslope. Again, the sampling location was chosen on the
basis of the appearance of very short vegetation relative to the surround-
ing area. The ESP did not exceed 3 in this pedon.
Site 4 was sampled from an oval-shaped upland depression in southern
Morris County, Kansas, approximately 20 by 15 m in diameter, which is
too small to be mapped at the scale of mapping (i.e., 1:20,000; Barker,
1974). The area was a closed upland depression in which vegetation
was shorter and sparser than the surrounding vegetation and populated
with sedges (Fig. 2). Pedon 06KS127001 meets the criteria for a Natrus-
toll; ESP values ranged between 19.9 and 27.9% in the argillic horizon at
depths of 13 to 87 cm. This pedon’s classification was, therefore, revised
post-characterization to a fine, smectitic, mesic Typic Natrustoll. This
site was characterized with an EM-38M on a subsequent USDA-NRCS
training exercise, and Fig. 3 was prepared by Wes Tuttle, Geophysical
Soil Scientist, USDA-NRCS National Soil Survey Center. Figure 3 illus-
trates the approximate dimension and shape and the apparent EC (for
Table 4. Selected field and laboratory characterization data for soils from MLRA 76 in Kansas.
Horizon Depth Munsell colorCoarse
fragments Redox PSD Total C§ pH (1:1 H2O)pH (1:2 0.01
M CaCl2) ESPcm %
Site 2, Pedon ID 05KS127005Ap 0–17 10YR 3/2 – – sil 2.39 6.1 5.9 1.70Bt 17–40 10YR 2/2 2, 3 – sic 1.30 6.6 6.2 3.95“ 40–65 10YR 2/2 – – sic 0.96 6.9 6.3 5.47Btk1 65–77 10YR 3/3 – 1 FMM, 1FMN sic 0.69 7.3 6.8 5.45Btk2 77–118 10YR 4/3 – 2 FMM, 2FMN sicl 0.39 7.8 7.2 1.412Bt 118–182 7.5YR 4.4 5, 3 2 FMM, 2FMN sicl 0.29 7.6 7.0 1.343Cr 182–197+ nd soft limestone – nd 2.32 8.6 7.5 0.00Site 4, Pedon ID 06KS127001A 0–13 10YR 3/2 – – sicl 2.06 6.7 6.1 7.57Bt1 13–26 10YR 2/2 – – sic 1.31 6.7 6.5 19.88Bt2 26–42 10YR 2/2 – 2 F3M sic 1.07 7.1 7.0 25.17Bt3 42–51 10YR 3/3 – 2 FMM, 2 F3M sic 0.82 7.3 7.2 27.88Btk 51–75 10YR 4.2 – 2 FMN, 2 F3M sic 0.50 7.6 7.5 25.742Bt 75–87 7.5YR 4.3 – 2FMM, 10 F3M, 2 F2M sic 0.44 7.5 7.5 24.253Cr 87–88+ 10YR 7.2 soft limestone – nd nd nd nd ndSite 9, 06KS015006A 0–13 10YR 3/2 – – sicl 2.51 5.7 5.0 4.65Bt1 13–31 10YR 2/2 1, 5 5 FMN, 2 F3M sic 1.29 6.7 6.0 7.91Bt2 31–53 10YR 3/2 1, 5 5 FMN, 5 F3M sic 1.00 7.4 6.7 8.292Btkss1 53–77 7.5YR 3/3 2, 5 5 FMN, 5 F3M sic 0.58 7.5 6.8 13.512Btkss2 77–97 5YR 4/4 2, 5 5 FMN, 10 F3M sic 0.37 7.9 7.3 14.912Bty 97–130 5YR 3/4 2, 5 5 FMN, 20 F3M sic 0.31 7.9 7.2 14.983R 130+ nd hard limestone–Site 10, 06KS015007A 0–6 10YR 2/2 – – sil 2.60 5.6 5.1 4.09BA 6–17 10YR 2/2 – – sicl 1.68 6.3 5.2 6.23Bt1 17–31 10YR 3/2 – 5 FMN, 4 F3M sic 1.24 7.1 5.8 7.50Bt2 31–49 10YR 3/3 – 5 FMN, 10 F3M sic 0.89 7.6 6.5 8.26Bt3 49–61 10YR 3/3 – 5 FMN, 10 F3M sic 0.75 7.1 6.7 10.18Btk1 61–80 10YR 4/3 – 5 FMN, 10 F3M sic 0.53 7.5 7.1 10.852Btk2 80–96 7.5YR 4/3 1, 5–10 5 FMN, 5 F3M sic 0.55 7.1 7.0 11.193Bty 96–119 5YR 4/4 3, 5–10 5 FMN, 5 F3M sic 0.28 7.5 7.2 11.434Btyss 119–141 5YR 4/4 5, 5–10 20 FMN, 10 F3M sic 0.27 8.0 7.2 10.884Btyss 141–160 5YR 4/4 5, 5–10 20 FMN, 10 F3M sic 0.18 8.1 7.3 10.634Btyss 160–177+ 5YR 4/4 5, 5–10 20 FMN, 10 F3M sic 0.17 8.0 7.4 9.06
† FMM, iron-manganese masses; FMN, iron-manganese nodules; F3M, iron concentrations, F2M, iron depletions.‡ sicl, silty clay loam; sil, silt loam; sic, silty clay.§ Total C, total carbon (%); nd, not determined.¶ ESP, exchangeable Na+ percentage.
Fig. 2. Upland depression where Site 4, Pedon 06KS127001, was sampled in MLRA 76 in Kansas. The depression is 20 by 15 m in area.
6 S O I L S U R V E Y H O R I Z O N S
the 0–1.5 m depth) of Site 4. The dimensions and shape are
very typical of the bison wallows and sparsely vegetated
upland depressions observed throughout MLRA 76. A total
of 445 measurements were recorded with the EM-38M in the
vertical dipole orientation. Apparent conductivity averaged
34.0 mS/m and ranged from 18.5 to 122.6 mS/m. One-half
of the observations had an apparent conductivity between
24.4 and 31.2 mS/m. Pedon 4 was sampled very near the
center of the depression (Fig. 3), and thus changes in spatial
conductivity patterns were thought to reflect changes in Na
concentrations across the survey area.
Sites 5 and 6 were sampled from a different upland depres-
sion on the same property as Site 4 in southern Morris
County, Kansas. Site 5 did not meet the natric horizon criteria
as the ESP was less than 6 in the upper 40 cm of the argillic
horizon. Site 6, however, did meet the criteria as the ESP was
16.46 in the Bt2 horizon (32–58 cm) and within 40 cm of the
upper boundary of the argillic horizon.
Site 7 was sampled in northern Chase County, Kansas.
Although it is not technically located within the boundar-
ies of MLRA 76, the landscape and all soil forming factors
were consistent with those of the other 10 pedons. Pedon 7
was sampled within a Dwight map unit on a backslope with
Fig. 3. Apparent electrical conductivity map of Site 4 in MLRA 76 in Kansas. The star symbol indicates the sampling location for Site 4, pedon 06KS127001.
Fig. 4. Relationships between exchangeable Na+ percentage (ESP), pedon features, and landscape features for soils from MLRA 76 in Kansas.
7S p r i n g 2 0 1 1
greater maximum profile ESP values were observed within the shallow-
est pedons, though this relationship was not statistically significant (Pr >
F 0.2533) for pedons included in this dataset. Note that only 8 of the 11
observations were used because the total solum depth was unknown for
3 of the 11 pedons. Wehmueller’s personal experience, along with infor-
mation from the USDA’s National Cooperative Soil Survey, was that the
only pedons in MLRA 76 that will meet the natric criteria are those that
are »1 m or less over bedrock. Three pedons in the National Soil Survey
Characterization database (59KS015003, 59KS015007, and 91KS161006)
that meet these criteria had R horizons present at 109, 107, and 76 cm,
respectively (National Cooperative Soil Survey, 2010).
No trend was observed for total solum depth and the upper boundary
for the horizon in which the greatest ESP was observed in the profile
(Fig. 4C). Another hypothesis was that soils sampled on flatter or con-
cave slope positions would have greater maximum ESP values. In this
study, the slopes ranged from 0 to 3%, and 5 of 11 pedons were sam-
pled from upland depressions (slope = 0%). There appeared to be no
relationship between slope and the maximum ESP observed in the soil
profiles (Pr > F 0.5584).
ConclusionsThe 11 pedons of this study were sampled from areas of very short,
sparse vegetation, and 5 of the 11 were sampled from upland depres-
sions. Neither landscape position, slope, location within an upland
depression, nor presence of short, sparse vegetation were sufficient
predictors for the presence of a horizon that met the criteria for a natric
diagnostic horizon. Greater maximum profile ESP values were observed
within the shallowest pedons (Pr > F 0.2533), those that were »1 m to
bedrock. Therefore, the original question remains: How can a person
recognize natric soils in the field without the use of geophysical tools
such as an EM-38? Also, if pedons containing a natric horizon are so
difficult to find, should 114,799 ha of Natrustolls be mapped within the
19,567-km2 MLRA 76 (»5.8% of the land area of MLRA 76)? Of the 11
pedons studied, which were, on the basis of landscape and vegetation,
most likely to meet the criteria for Natrustolls, only two were classified
as such. Using the appearance of vegetation, whether in a depression
or not, doesn’t seem to help with classification and, ultimately, mapping.
Considering the effect that these moderately high Na+-containing soils
have on vegetation and land use, perhaps a useful addition to Soil Tax-
onomy would be the creation of paranatric diagnostic horizon criteria
and/or a Natric subgroup of Argiustolls. As observed in this study,
ESP values of »5 to 14% were detrimental to the rangeland vegeta-
tion; therefore, this range could potentially be used in the paranatric
diagnostic horizon criteria or for the classification criteria for a Natric
Argisutoll subgroup. Specifically, a possible suggestion for inclusion
in the proposed “paranatric criteria” could be an ESP of ³5 or <15%
or SAR of >4 or £13 within 40 cm of the upper boundary of the argillic
horizon. Criteria for Natric Argiustolls (and potentially other subgroups
such as Natric Paleustolls) would be the recognition of a paranatric
diagnostic horizon (if accepted into Soil Taxonomy), or the classifica-
tion criteria could simply be the ranges in ESP or SAR given above.
Field soil scientists could use sparse, short vegetation in native range
as a good indicator of paranatric conditions and use it to delineate
boundaries on soil maps or in association with a spot symbol and then
follow up their visual observations with geophysical tools such as an
2% slope, and the grass was very short. The vegetation was identified
as broom snakeweed, which is considered a poor-quality rangeland
plant and is often associated with overgrazing or disturbance (Owensby,
2004). The ESP values did not exceed 9 in the upper 40 cm of the pedon
or anywhere in the profile.
Site 8 was sampled from an area of short grass within a Ladysmith map
unit on native rangeland in northern Butler County, Kansas. The ESP
values were <12 in the upper 40 cm of the argillic horizon and through-
out the profile.
Sites 9 and 10 were sampled from adjacent areas within a native pasture
in central Butler County, Kansas. Site 9 was within a Dwight map unit, and
Site 10 was within an Irwin map unit. Site 9 was described as having short
grass, whereas Site 10 was sampled from within an area of taller grass
with shorter grass encircling the area. The ESP values for Site 9 were <9
in the upper 40 cm of the argillic horizon (13–53 cm); however, the ESP
was nearly 15 in the lower part of the argillic horizon (53-130 cm). There-
fore, Site 9 would not meet the natric criteria but would be a good fit for
the Konza series (Wehmueller, 1996; Glaze, 1998). Site 10 had ESP values
ranging from 7.5 to <11 in the upper 40 cm of the argillic horizon as well
as in the lower part of the profile. It is interesting that although these two
pedons had markedly different grass morphology, they had similar ESP
values in the upper part of the profile. It is possible that the difference
was due to the high Na+ content in the lower part of the profile of Pedon 9.
Site 11 was sampled in southeast Butler County, Kansas, from an upland
depression within a Ladysmith map unit on a native rangeland pasture.
The ESP values in the upper 40 cm of the argillic were between 9 and 11
and increased to <13 at lower depths in the profile.
Sodium Accumulation and Particle-Size Distribution within Pedons
The ESP values were greatest in the horizons with the finest textures,
which was similar to the findings of Glaze (1998) and White (1999). The
ESP and particle-size distribution tended to follow one of three patterns
in these profiles: (1) increased with increasing depth irrespective of the
solum depth or changes in parent materials (Pedons 4, 5, 6, 9, 10); (2)
increased within the profile and then decreased within the depth sam-
pled, with the highest values in the modern soil profile (i.e., the clay and
ESP decreased in the second parent material; Pedons 2, 3, 8); or (3)
bimodal with two peaks in the clay and ESP, in which the ESP was great-
est in the lower part of the paleosol (Pedons 1, 7, 11).
Relationships between Sodium Accumulation, Solum Thickness, and Slope
Correlation analysis was used to search for and examine the strength of
possible relationships between the ESP values, selected pedon features,
and landscape features (slope). The goal was to select and analyze rela-
tionships that a soil scientist could use to correctly predict the presence
of a natric diagnostic horizon while mapping in the field.
There was no relationship observed between the depth at which the
maximum ESP value was observed in the profile and the maximum
pedon ESP value (Fig. 4A). A very weakly negative relationship between
the thickness of the solum and the maximum ESP was observed (Fig. 4B)
and was consistent with anecdotal information from one NRCS soil sci-
entist (William Wehmueller, personal communication, 2010). Therefore,
8 S O I L S U R V E Y H O R I Z O N S
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Ladd, D. 1995. Tallgrass prairie wildflowers: A field guide. Falcon Publishing, Helena, MT.
McMillan, B.R., M.R. Cottam, and D.W. Kaufman. 2000. Wallowing behav-ior of American Bison (Bos bison) in tallgrass prairie: An examination of alternate explanations. Am. Midl. Nat. 144:159–167. doi:10.1674/0003-0031(2000)144[0159:WBOABB]2.0.CO;2
National Cooperative Soil Survey. 2010. Soil characterization data. Available at http://ssldata.nrcs.usda.gov/ (verified 2 Mar. 2011).
Owensby, C.E. 2004. Kansas prairie wildflowers. KS Publishing, Inc., Manhattan, KS.
Presley, D.R. 2007. Genesis and spatial distribution of upland soils in east central Kansas. Ph.D. diss. Kansas State Univ., Manhattan. Available at http://www.proquest.com/(publication number AAT 3259326) (verified 2 Mar. 2011).
Presley, D.R., P.E. Hartley, and M.D. Ransom. 2010. Mineralogy and morphological properties of buried polygenetic paleosols formed in late quaternary sediments on upland landscapes of the central plains, USA. Geoderma 154:508–517. doi:10.1016/j.geoderma.2009.03.015
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Schoeneberger, P.J., D.A. Wysocki, E.C. Benham, and W.D. Broderson (ed.) 2002. Field book for describing and sampling soils. Version 2.0. NRCS, National Soil Survey Center, Lincoln, NE.
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USDA-NRCS. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. USDA Agric. Handb. 296.
Wehmueller, W.A. 1996. Genesis and morphology of soils on the Konza Prairie Research Natural Area, Riley and Geary Counties, Kansas. M.S. thesis. Kansas State Univ. Manhattan.
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EM-38 or focused soil sampling for lab analyses. If no changes are
made to Soil Taxonomy, the suggested criteria ESP range (5–14) could
alternatively serve as criteria used to set up a new series. Soils that
do not meet the current natric criteria default to either an Argiustoll or
Paleustoll in the Great Plains, neither of which can convey the impor-
tance of the poor vegetation and its impact on rangeland, which is the
predominant land use in MLRA 76, as well as other large tracts of land
in the Great Plains.
Patches of short and sparse vegetation are quite abundant, which is
important information for grazingland managers, and would be a useful
visual cue for mappers in the field to recognize soils with moderately
high Na+ content. In conclusion, these findings indicate the need for
future investigations of the soils that do not currently meet the natric
diagnostic horizon criteria and which are found beneath other sparsely
vegetated areas of rangeland in both MLRA 76 and other predominantly
grassland areas of the Great Plains.
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