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 (deann@ksu.edu) 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

Rhoades, J.D., P.A. Raats, and R.J. Prather. 1976. Effects of liquid-phase elec-trical conductivity, water content, and surface conductivity on bulk soil electrical conductivity. Soil Sci. Soc. Am. J. 40:651–655. doi:10.2136/sssaj1976.03615995004000050017x

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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Trager, M.D., G.W.T. Wilson, and D.C. Hartnett. 2004. Concurrent effects of fire regime, grazing, and bison wallowing on tallgrass prairie vegetation. Am. Midl. Nat. 152:237–247. doi:10.1674/0003-0031(2004)152[0237:CEOFRG]2.0.CO;2

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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Darton, N.H. 1905. Preliminary report on the geology and underground water resources of the central Great Plains. Prof. Paper 32. USGS, Gov. Print. Office, Washington, DC.

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Glaze, S.L. 1998. Sodium accumulation and genesis of polygenetic soils in north central Kansas. M.S. thesis. Kansas State Univ., Manhattan.

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