APRIL 19-24, 2015
Hosted by the School of Agriculture
University of Arkansas at Monticello
Monticello, Arkansas
Table of Contents
Welcome, Introduction ..................................................................................................
1
Conduct of the Contest ..................................................................................................
2
Scoring ...........................................................................................................................
3
Scorecard Instructions ....................................................................................................
5
Soil Profile Characteristics .............................................................................................
13
Site Characteristics .........................................................................................................
16
Soil Classification ...........................................................................................................
22
Soil Interpretations ..........................................................................................................
23
Appendix 1 Example of Site Card .................................................................................
27
Appendix 2 Official Abbreviations and USDA Texture Triangle .................................
28
Appendix 3 Simplified Key to Soil Sub-Order and Great Group ..................................
30
Appendix 4 Rating Guide For Soil Interpretations ........................................................
40
Appendix 5 Seasonal Water Table (SWT) Classes ........................................................
41
Appendix 6 Loading Rates (gpd/ft2) For On-Site Wastewater Disposal ........................
42
Appendix 7 Scorecard .....................................................................................................
44
Illustrated Guide to Soil Taxonomy, version 1.0
http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/class/?cid=nrcs142p2_053580#illustrated
i
WELCOME, INTRODUCTION
It is a great honor to host the 2015 American Society of Agronomy National Soils Contest here at the
University of Arkansas at Monticello, home of the ‘Boll Weevils’. We are excited to welcome the best
and brightest soil science students from across the U.S. to our region of the world and hope that your
experience will be educational, inspirational, and filled with fond memories and new friends who will soon
be fellow colleagues. Collegiate soil judging is sponsored by the Students of Agronomy, Soils, and
Environmental Sciences (SASES), which is an undergraduate student organization of the American Society of
Agronomy (ASA), Crop Science Society of America (CSSA), and Soil Science Society of America (SSSA).
Information on eligibility, membership, contest procedures, conduct, and qualification for the International Soil
Judging Competition can be found at https://www.soils.org/undergrads/soils-contest.
This handbook provides detailed information on conduct of the contest, scorecard instructions, and other
relevant information. Much of the material comes from previous ASA National Soils Contests, but some minor
modifications were made based upon regional interpretations, and input from students, coaches, and NRCS Soil
Scientists. Other references used to develop this handbook include: Chapter 3 of the Soil Survey Manual (Soil
Survey Division Staff, 1993), Field Book for Describing and Sampling Soils, version 3.0 (Schoeneberger et al.,
2012), Soil Taxonomy (Soil Survey Staff, 1999), Keys to Soil Taxonomy 12th Edition (Soil Survey Staff,
2010), and the National Soil Survey Handbook (Soil Survey Staff, 1996).
We are appreciative for the technical support provided by the ‘soils team’ of soil scientists from the Arkansas
USDA-NRCS and Arkansas Association of Professional Soil Classifiers, the many volunteers and landowners,
and the financial assistance from the Soil Science Society of America and American Society of Agronomy,
Drew County Farm Bureau, Drew County Conservation District, the University of Arkansas at Monticello, and
local businesses. This contest would not be possible without the unselfish efforts of these individuals,
businesses, and organizations.
Paul B. Francis, Professor
Plant and Soil Science
School of Agriculture, Univ. Arkansas at Monticello
Monticello, AR 71656
870-460-1314
[email protected]
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CONDUCT OF THE CONTEST
1. Contest Sites
The contest will consist of two sites for group judging and three sites for individual judging with
additional sites available for practice prior to the competition. At each site, a pit will be excavated
exposing a profile. One or two area(s) will be selected in each pit and clearly designated as the control
section by the contest officials. These areas are ‘no pick’ zones but are used for measurement of horizon
depths and boundaries. The selected areas will constitute the officially scored profiles and must remain
undisturbed and unblocked by contestants. All measurements should be made within these designated
areas. Measuring tapes will be placed in all contest pits and will be maintained by official pit monitors.
Contestants will be told which profile they are to evaluate if more than one is selected in a pit. The
contestants will describe up to six horizons within a given depth. A card at each site will give the profile
depth to be considered, the number of horizons to be described, the depth of a nail within the third horizon,
and chemical or physical data that may be required for classification. An example of the site card is
included in Appendix 1. A topographic map and/or aerial imagery of the area with the sites located may
be provided to help contestants orient themselves to the landscape. Changes to the group/individual
contest schedule and the “time in and out” of pits may be made prior to the coaches meeting depending on
the number of participants and pit and weather conditions.
2. Equipment and Reference Materials
The equipment and reference materials listed below will be permitted during the contest. Any contestant
found in possession of equipment or reference materials other than those listed below will be disqualified.
Allowed equipment:
clipboard
Abney level or clineometer
Munsell Soil Color Chart
non-programmable calculator
soil knife or other digging tool
pencils (No. 2 suggested)
small pencil sharpener
hand lens
water bottle
hydrogen peroxide (2%), HCl (10%) dropper bottle
hand towel
containers for soil samples
tape measure
2 mm sieve
Allowed reference materials:
List of accepted abbreviations and texture triangle (Appendix 2) – provided during contest.
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Rating guide for soil interpretations (Appendix 4) – provided during contest.
Seasonal water table (SWT) classes (Appendix 5) – provided during contest.
Loading rates (gpd/ft2) for on-site wastewater disposal (Appendix 6) – provided during contest.
3. Individual Competition
Sixty minutes will be allowed for evaluating each site for individual judging. Contestants will be assigned
by team number to one of two groups at each site. One group will follow this schedule: 10 minutes in the
pit, 10 minutes out, 10 minutes in, 10 minutes out, and 20 minutes free-for-all. The other group will
follow the opposite in-and-out schedule. At alternating sites the contestants will switch the in-and-out
schedule. Contestants may obtain a sample from the surface horizon while out of the pit, provided they do
not enter the pit or disturb those already in the pit.
Individual contestants will be assigned a number that will be used to identify their scorecard and the
rotation schedule. The procedures for student rotation and time in and out of the pit may be altered prior
to the contest to meet unanticipated difficulties at the site.
4. Group Competition
Forty five to 50 minutes will be allowed for groups to evaluate each of the two sites. The time will be
divided into 10-minute segments similar to the individual competition. Universities will be randomly
assigned a group number at registration. All students from a university may participate in the group
contest. The start time(s) of the group contest will be announced at the coaches meeting.
SCORING
1. General
All contestants will use the standard scorecard depicted in Appendix 7. It will consist of five sections. All
boxes on the scorecard will be scored for the number of horizons required. If no entry is needed, then the
contestant must enter a dash (---). Boxes left blank will be marked wrong. A list of acceptable
abbreviations can be found in Appendix 2; each contestant will receive a copy for use during the contest.
Illegible entries, as determined by multiple graders, or any abbreviations other than those listed in
Appendix 2 will be marked wrong. Input from coaches on scoring decisions is welcome, but decisions of
the contest officials will be final. If a pedon has more than one parent material or diagnostic subsurface
horizon/feature, 5 points will be awarded for each correct answer. In these sections of the scorecard,
negative credit (minus 5 points for each extra answer, with a minimum score of zero for any section) will
3
be used to discourage guessing. More than one entry in other areas of the scorecard that require one
answer will be considered incorrect, and will result in no credit for that item. For example, if loess and
alluvium are the correct parent materials, then 5 points will be awarded for each. If a contestant checks
loess (+5) and colluvium (0), the score would be 5; and if the contestant checked loess (+5), alluvium (+5),
and colluvium (-5 extra answer) the score would be five because of the excessive answer. Omissions will
not be given any points. In all other situations, points will be awarded as indicated on the scorecard.
2. Score Tabulation
The overall team score will be the sum of the top three individual scores achieved by the four members
selected to participate in the individual competition plus the scores from the group competition. In this
manner, all four team members may contribute to the overall team score. An example of the scoring for
the individual portion of the contest is shown below:
INDIVIDUAL
SITE 1
SITE 2 SITE 3
TOTAL
A
232
241
254
727
B
261
262
313
836
C
208*
277
251*
736
D
275
234*
289
798
Scores used for
individual
ranking
Total
768
780
856
2404 = Team score
* Lowest score is not used to determine team score.
The team score from is then added to the scores for the two group sites to determine the overall team
score.
Only one official team is permitted from a university. Alternates not on the official team can judge
practice sites and participate in the group competition, but only four students from each university will be
allowed to participate in the individual competition. These members must be designated by Weds., April
22, 2015.
3. Tie Breaker – Overall Team
In case of a tie, the percent clay content of the third horizon at site #1 will be used. The mean clay content
will be calculated from the estimates provided by all members of a given team. The team with the mean
estimate closest to the actual value will win. For example:
Actual clay content of tie breaker horizon = 33%
4
Team estimates:
TEAM #5
TEAM #7
Individual A = 38%
Individual E
= 33%
Individual B = 34%
Individual F
= 29%
Individual C = 30%
Individual G = 22%
Individual D = 39%
Individual H = 30%
Mean
Mean
= 35%
= 29%
Clay Content = 33%
Clay Content = 33%
Difference
Difference
= 2%
= 4%
In this example, TEAM #5 is the winner.
If a tie still exists, the clay content of the third horizon at site #2 will be compared, followed by the third
horizon at site #3 if necessary. If this does not break the tie, the next (lower) horizon(s) will be used in the
same manner and order.
4. Tie Breaker – Individual and Group
The actual clay content of the third horizon at site #1 will be compared to that estimated by each individual
or group tied. If a tie still exists, the clay content of the third horizon at site #2 will be compared, followed
by the third horizon at sites #3 and #4 if necessary. If this does not break the tie, the next (lower)
horizon(s) will be used in the same manner and order.
5. Awards
At minimum, plaques or trophies will be awarded to top ten overall individuals, the top five universities in
the group contest, and top five overall teams. The travelling National Collegiate Soils Contest Trophy goes
to the team with the highest overall team score.
Scorecard Instructions
The scorecard consists of five parts:
I. Soil Morphology, II. Soil Profile Characteristics, III. Site
Characteristics, IV. Soil Classification and V. Soil Interpretation. The points for each item are indicated
on the score card. The Soil Survey Manual (USDA Handbook no. 18, 1993 edition) and Keys to Soil
Taxonomy, 12th edition (2014), will be used as guides whenever possible.
SECTION I: SOIL MORPHOLOGY
A. Horizonation
(1) Master
5
a. Prefix In mineral soils, Arabic numerals are used as prefixes to indicate that a soil has not
formed entirely in one kind of material, which is referred to as a lithologic discontinuity, or just
a discontinuity. Wherever needed, the numerals precede the master or transitional horizon
designation. A discontinuity is recognized by a significant change in particle-size distribution
or mineralogy that typically indicates the horizons formed in different parent materials or have
a significant difference in age (unless already denoted with the suffix b). Stratification common
to soils formed in alluvium is typically not designated as a discontinuity, unless particle-size
distribution differs markedly from layer to layer (is strongly contrasting), even if genetic
horizons have formed in the contrasting layers.
When a discontinuity is identified, prefix numbering starts in the underlying (second) deposit.
The material underlying the surficial deposit is designated by adding a prefix of “2” to all
horizons and layers that formed in the second material underlying the discontinuity. There is no
minimum number of horizons and layers needed in materials that underlie the surficial deposit.
If another discontinuity is found below material with prefix “2”, the horizons and layers formed
in the third material are designated by a prefix of “3”. For example, Ap, E, Bt1, 2Bt2, 2Bt3,
3BC. The number suffixes designating subdivisions of the Bt horizon continue in consecutive
order across the discontinuity. A discontinuity prefix is not used to distinguish material of
buried (b) horizons that formed in material similar to that of the overlying deposit (no
discontinuity). For example, A, Bw, C, Ab, Bwb1, Bwb2. However, if the material in which a
horizon of a buried soil is in a discontinuity below the overlying material, the discontinuity is
designated by number prefixes and the symbol for a buried horizon is used as well, e.g., Ap,
Bw, C, 2Ab, 2Bwb, 2C.
If a pedon contains two or more horizons of the same kind which are separated by one or more
horizons of a different kind, identical letter and number symbols can be used for those horizons
that have the same characteristics, for example, the sequence A-E-Bt-E-Btx-C. The prime (‘),
when appropriate, is applied to the capital-letter horizon designation, and any lower-case letter
symbols that follow it, e.g. A-E-Bt-E’-Btx-C. It is used only when the letter designations of the
two layers in question are completely identical.
b. Master. The second column is to indicate the appropriate master horizon designations (i.e.,
A, E, B, C, or R) and combinations of these letters (e.g., AB, E/B, etc.). The prime ( ’), used
for horizons having otherwise identical designations, should also be included in this column
6
after the master horizon designation. O horizons or layers will not be described in this contest.
All depth measurements should be taken from the marker in the third horizon. R horizons
should be identified in the Master column, if within the judging depth. However, they will not
otherwise be described, so all other columns in that row should be marked with a dash. This is
also true for Cr horizons except that the C is in the master horizon and the r in the subordinate
distinction, which follows.
(2) Sub. Subordinate Distinctions.
Enter lower case letters to designate specific kinds of master horizons if needed. If none, enter
a dash. Students should be familiar with applications of the following subordinate distinctions:
b (buried genetic horizon), c (concretions or nodules), k (accumulation of carbonates,
commonly calcium carbonate), g (strong gleying), n (pedogenic, exchangeable sodium
accumulation), p (tillage or other disturbance), r (weathered or soft bedrock), ss (slickensides),
t (accumulation of silicate clay), v (plinthite), w (development of color or structure), x
(fragipan characteristics) and y (pedogenic accumulation of gypsum). If used in combination,
the suffixes must be written in the proper order. NOTE: a subordinate distinction always
follows the B master horizon. Subordinate distinctions on transitional horizons will be used
when the horizon is transitioning from or to a B horizon (i.e. AB, BA, BC). The subordinate
distinction will reflect the subordinate distinction(s) used with the B horizon (i.e. BCt). Contest
officials will communicate the use of subordinate distinctions on transitional horizons to
coaches through their use at practice sites.
The suffix b will be used only when a buried solum, including an A horizon, is clearly
expressed. The suffix c will only be used for concretions or nodules that are cemented, but not
with silica. It is not used if the concretions or nodules consist of dolomite or calcite or more
soluble salts, but it is used if the concretions or nodules are enriched with minerals that contain
iron, aluminum, manganese, or titanium.
A Bw is not used to indicate a transitional horizon or a horizon that would be transitional if the
entire pedon were present.
7
(3) No. Numerical Subdivisions
Enter Arabic numerals whenever a horizon identified by the same combination of letters needs
to be subdivided. If a subordinate distinction or a numerical subdivision is not used with a
given master horizon, enter a dash in the appropriate space on the scorecard.
(4) Lower Depth
Up to six horizons will be described within a specified depth noted on the site card. The depth
provided on the site card is not used for any other purpose than describing horizon morphology
in Section I. Determine the depth (in cm) from the mineral soil surface to the lower boundary
of each horizon except the last horizon. For example, a Bt1 horizon that occurs between 23 and
37 cm below the soil surface, enter "37." The last horizon boundary should be the specified
judging depth with a "+" added, unless the specified depth is at a very evident horizon
boundary, such as a lithic or paralithic contact, then the "+" is not used.
If a lithic or paralithic contact occurs at or above the specified depth on the site card, the
contact should be considered in evaluating the available water holding capacity, effective soil
depth, and limiting hydraulic conductivity. Otherwise, the last horizon should be assumed to
extend to 150 cm for making all relevant evaluations. If a lithic or paralithic contact occurs
within the specified depth, the contact should be considered as one of the horizons to be
included in the description, and the appropriate horizon nomenclature should be applied (i.e.,
Cr or R). However, morphological features need not be provided and dashes should be used on
the scorecard. If the contestant gives morphological information, it will be ignored by the
graders and will not count against the total score. If in doubt concerning the nature of the
horizon, the contestant would is advised to provide all of the information for that horizon.
In the contest, horizons less than 8 cm thick (no matter how contrasting) will not be described,
although thinner horizons may be described in the practice pits. If a horizon less than 8 cm
thick occurs, combine it for depth measurement purposes with the adjoining horizon that is
more similar (e.g., a thin, discontinuous E horizon might be combined with an adjoining BE).
When two horizons are combined to give a total thickness of 8 cm or more, always describe the
properties of the thicker horizon.
All depth measurements should be taken from the nail in the ‘no pick’ zone. The allowed range
to be considered correct will depend upon the distinctness of the boundary as detailed below.
8
(5) Dist. Distinctness of Boundary
The distinctness of lower horizon boundaries is to be evaluated as per the Soil Survey Manual
(p 133). The distinctness of the lower boundary of the last horizon is not to be determined
unless it is at a lithic or paralithic contact. If the lower depth to be judged is at a lithic or
paralithic contact, indicate the distinctness, if there is no lithic or paralithic contact, place a
dash (---) in the box. The topography or shape of the boundaries will not be recorded.
Distinctness of Boundary
Range For Grading
Abrupt (A)
±1 cm
Clear (C)
±3 cm
Gradual (G)
±8 cm
Diffuse (D)
±15 cm
B. Texture
(1) Clay
Estimates of percent clay should be made for each horizon and entered in the appropriate
columns. Answers within plus or minus 10% of the actual values will be given full credit.
Actual content of clay was determined by the hydrometer method (2 hrs 40 min).
(2) Percentage Coarse Fragments
Estimates of the volume percentage coarse fragment should be made for each horizon and
entered in the appropriate column, rounded to the nearest 1.0%. Estimates should be made only
within the no-pick zone. If no coarse fragments are observed, enter a 0 on the scorecard. For
horizons having 1-100% coarse fragments, credit will be given within plus or minus 10% of the
official values.
(3) Coarse Fragment Modifer.
Modification of textural class is made, if needed, in the coarse fragment column, when the soil
contains more than 15% by volume coarse fragments. For the purposes of this contest, the
following modifiers will be used when the volume of rock fragments is between 15 and 35%.
9
a. Gravelly [GR] (2-76 mm diameter)
b. Cobbly (includes stones and boulders) [CB] (> 76 mm diameter)
If the volume of coarse fragments is between 35 and 60%, prefix the appropriate modifier
with the word “very” [V]. If the volume is greater than 60%, use the prefix "extremely" [E].
Enter the correct abbreviation for the coarse fragment modifier in the Coarse Frag. column,
not in the texture class column. If coarse fragments do not exceed 15% enter a dash in the
space on the scorecard.
If a relatively equal mixture of sizes occurs within a horizon, the total percentage of coarse
fragments (all sizes) is used to determine the modifier prefix and the largest size class (most
mechanically restrictive) is named. The smaller size class is named only if the quantity
(vol.%) is 2 times the quantity of the larger size class. For example, a horizon with 30%
gravels and 10% cobbles would be very gravelly (VGR), but a horizon with 15% gravels and
10% cobbles would be cobbly (CB).
(4) Class
The textural class for the less than 2 mm fraction of each horizon is to be entered in the
column labeled Class; the only acceptable abbreviations are given in Appendix 2. For sand,
loamy sand, and sandy loam texture classes, modifiers will be used if needed [i.e., very fine
(VF), fine (F), or coarse (CO)]. Enter the abbreviation for only one class. More than one may
be considered correct by the official judges, but if a contestant enters more than one class, the
entire entry is wrong.
C. Color
Munsell soil color charts must be used to determine the moist color of each horizon described.
Colors must be designated by Hue, Value, and Chroma. Color names such as "pale brown" will
not be accepted as correct answers. Partial or full credit may be given for colors close to the
official evaluation, either in hue, value, or chroma. In the case of surface horizons, color is to be
determined on crushed samples. The color recorded for soil material from any other horizon,
including a mottled horizon, should be the dominant, unrubbed color of the ped interior, not a ped
surface or cutan. The dominant color may or may not be the matrix color. Blue-cover Munsell
color charts are used by the official judges.
10
D. Structure Grade and Shape
Record the dominant Grade and Shape of structure as defined in the Soil Survey Manual (p. 157163). If different kinds of structure occur in different parts of the horizon, give the shape and grade
of the structure that is most common. If the most common structure is compound (one kind
breaking to another), describe the one having the stronger grade. If they are of equal grade, give
the one with the larger peds. Numerical notations will be utilized for grade of structure. If the soil
materials are structureless (massive or single-grained), enter "0" under grade
E. Consistence
Determine Moist Strength at approximately field capacity for each horizon. It is considered
impractical to use the definitions in the 1993 Soil Survey Manual for contest purposes and therefore
the following definition from the 1951 Soil Survey Manual will be used (p. 154-156):
Consistence when moist is determined at a moisture content approximately midway between
air-dry and field capacity. At this moisture content most soil materials exhibit a form of
consistence characterized by (a) tendency to break into small masses rather than into powder;
(b) some deformation prior to rupture; (c) absence of brittleness; and (d) ability of the material
after disturbance to cohere again when pressed together. The resistance decreases with
moisture content, and accuracy of field descriptions of this consistence is limited by the
accuracy of estimating moisture content. To evaluate this consistence, select and attempt to
crush in the hand a mass that appears slightly moist.
Abbreviation
Moist
consistence
Criteria
L
Loose
non-coherent
VFR
Very friable
FR
Friable
FI
Firm
VFI
Very firm
EFI
Extremely
firm
crushes under very gentle pressure but coheres when pressed
together
crushes easily under gentle to moderate pressure between
thumb and forefinger, and coheres when pressed together
crushes under moderate pressure between thumb and
forefinger but resistance is distinctly noticeable
crushes under strong pressure; barely crushable between
thumb and forefinger
Crushes only under very strong pressure; cannot be crushed
between thumb and forefinger and must be broken apart bit
by bit
11
F. Soil Features
Redox (RMF Depletions and Concentrations): Soils that have impeded drainage or high water
tables during certain times of the year usually exhibit redoximorphic (redox) features
(RMF) as a result of the movement of reduced iron and manganese. Redox features to be
considered for contest purposes include redox depletions (generally seen as gray zones)
and redox concentrations (generally seen as “red” zones of Fe accumulation or “black”
zones of Mn accumulation), which are a result of seasonal or permanent saturation. These
do not include colors inherited from parent materials.
Depletions: The presence or absence of redoximorphic depletions should be indicated for
each horizon. These are zones inside aggregates, along or inside root channels, or on
aggregate surfaces with high value (≥4) and low chroma (≤2) where either iron-manganese
oxides alone or both iron and manganese oxides have been reduced including:
(1) Iron and manganese depletions (zones which are depleted of oxidized forms of
iron and manganese due to reduction processes), and
(2) Clay depletions (zones which contain lower than their original amounts of clay
due to reduction and removal processes)
If the horizon is gleyed (meets the definition of “g” subordinate distinction), “Y” should
be indicated for RMF depletions. For determination of a seasonal high water table,
depletions of chroma 2 or less and value of 4 or more must be present.
Presence:
Yes (Y) RMF depletions are present.
No (---) RMF depletions are not present.
Concentrations: Redox concentrations may consist of zones of high chroma color, or the Fe
and Mn can accumulate into masses (concretions or nodules). Colors associated with the
following features will not be considered redoximorphic features: clay coatings (unless
their color results from reduction/oxidation), carbonates, krotovina, rock colors, roots, or
mechanical mixtures of horizons such as E or B horizon materials within an Ap horizon.
Presence: Yes (Y) RMF concentrations are present.
No (---) RMF concentrations are not present.
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II. SOIL PROFILE CHARACTERISTICS
A. Hydraulic Conductivity (HC)
Estimate the saturated hydraulic conductivity of the surface horizon (Hydraulic
Conductivity/ Surface) and the most limiting horizon (Hydraulic Conductivity/Limiting)
within the depth specified on the site card. If a lithic or paralithic contact occurs at or
above the specified depth, it should also be considered in evaluating conductivity.
Although unlikely, it is possible for the surface horizon to be the limiting horizon with
respect to saturated hydraulic conductivity. In this event, the surface conductivity would
be indicated as both the surface and limiting layer hydraulic conductivity.
Three general hydraulic conductivity classes are used:
High: Includes sands and loamy sands textures. Sandy loam, sandy clay loam,
silt loam, and loam textures that are especially "loose" because of very high
organic matter content (>5% organic carbon) also fall into this category. Loamy
soils in this category are typically not cultivated and are directly below an “O”
horizon (not described). Horizons containing >60% of coarse fragments with
insufficient fines to fill voids between fragments are also considered to have high
hydraulic conductivity .
Moderate: This includes those materials excluded from the "low" and "high"
classes.
Low: Low hydraulic conductivity should be indicated with the following:
1) Clays, silty clays, or sandy clays having structure grade of 0, 1 or 2.
2) Silty clay loams and clay loams that have structure grade of 0 or 1.
3) Bedrock layers (Cr or R horizons) where the horizon directly above
contains redoximorphic depletions or a depleted matrix due to
prolonged wetness (value ≥4 with chroma ≤2).
4) Massive, silt and silt loam E horizons, and all root-limiting horizons
(including fragipans, natric, and duripans) have low hyrdraulic
conductivity.
13
B. Effective Soil Depth
Soil depth classes as defined as the depth from the soil surface to the upper boundary of a
root restricting layer. Restrictive layers include: (i) horizons with coarse sand or rock
fragment modified coarse sand textures with some unfilled voids located directly
underneath a horizon of finer-textured soil materials (i.e., very fine sand, loamy very fine
sand or finer texture); (ii) bedrock (lithic or paralithic materials); (iii) root-limiting
horizons as defined in section A above; and (iv) very firm or extremely firm SiC, C, or SC
textures that are structureless and massive. If the lower depth of judging is less than 150
cm, and there is no restricting layer within or at the judging depth, the horizon
encountered at the bottom of the judged profile may be assumed to continue to at least 150
cm and “very deep” should be selected. Effective soil depth classes are:
Very Shallow
root restricting layer within 25 cm of soil surface
Shallow
root restricting layer from 25 to 49 cm
Moderately deep
root restricting layer from 50 to 99 cm
Deep
root restricting layer from 100 to 149 cm
Very deep
root restricting layer at 150 cm or deeper
C. Water Retention Difference
The water retention difference is approximately the water held between field capacity and
permanent wilting point. The approximate amount of moisture stored in the soil is
calculated for the top 150 cm of the soil. This soil thickness may or may not be the same
as that designated for purposes of profile descriptions. The total water is calculated by
summing the amount of water held in each horizon or portion of horizon, if the horizon
extends beyond 150 cm. If a horizon or layer is unfavorable for roots (as defined under
effective soil depth), this and all horizons below should be excluded in calculating the
available moisture. For water retention difference calculations, the properties of the lowest
horizon designated for description can be assumed to extend to 150 cm, if no restrictive
layer is present. If a restrictive layer is present between the lowest described horizon and
the 150 cm depth, the depth to the restrictive layer should be considered for water
retention difference estimations. Four retention classes listed will be used:
14
Very low:
Low:
Moderate:
High:
< 7.5 cm
7.5 to < 15.0 cm
15.0 to < 22.5 cm
≥ 22.5 cm
The relationship between water retention difference per centimeter of soil and the textures
is given in the table below. Coarse fragments are considered to have negligible (assume
zero) water retention, and estimates must be adjusted to reflect the coarse fragment
content. If a soil contains coarse fragments, the volume occupied by the rock fragments
must be estimated and the water retention difference corrected accordingly. For example,
if a silt loam A horizon is 25 cm thick and contains rock fragments which occupy 10% of
its volume, the water retention difference of the horizon would be 25 cm x 0.20 cm/cm x
[(100-10)/100] = 4.50 cm of water. Calculate the water retention difference for each
horizon to the nearest hundredth, sum all horizons, then round the grand total to the
nearest tenth. For example, 14.92 would round to 14.9 in the low class; 15.15 would round
to 15.2 in the moderate class.
Texture is an important factor influencing water retention difference. The following
estimated relationships are used:
Water retention
Textures
difference
(cm water per cm soil)
0.05
All sands, loamy coarse sand, and loamy sand
0.10
Loamy fine sand, loamy very fine sand, and coarse sandy loam
0.15
Sandy loam, fine sandy loam, sandy clay loam, sandy clay, clay,
and silty clay
0.20
Very fine sandy loam, loam, silt loam, silt, silty clay loam, and clay
loam
F. Soil Wetness Class
Soil wetness classes as defined in the Soil Survey Manual will be used. Soil wetness is a
reflection of the rate at which water is removed from the soil by both runoff and
15
percolation. Landscape position, slope gradient, infiltration rate, surface runoff, and
permeability, are significant factors influencing the soil wetness class. Redoximorphic
features, including concentrations, depletions and depleted matrix, are the common
indicators of prolonged soil saturation and reduction (wet state) , and are used to assess
soil wetness class. The following determines the depth of the “wet state”:
(1) The top of an A horizon with:
(a) Matrix chroma ≤2, and
(b) Redoximorphic depletions or redoximorphic concentrations as soft masses
or pore linings, and
(c) Redoximorphic depletions or a depleted matrix due to prolonged
saturation and reduction in the horizon directly below the A horizon, or
(2) The shallowest observed depth of value ≥4 with chroma ≤2 redoximorphic
depletions or depleted matrix due to prolonged saturation and reduction.
The wetness classes utilized in this contest are those which define a "depth to the wet state."
Class
Description
1
Not wet above 150 cm
2
Wet in some part between 101 and 150 cm
3
Wet in some part between 51 and 100 cm
4
Wet in some part between 26 and 50 cm
5
Wet at 25 cm or shallower
If no evidence of wetness is present above a lithic or paralithic contact that is shallower
than 150 cm, assume Class 1: not wet above 150 cm. If no evidence of wetness exists
within the specified depth for judging and that depth is less than 150 cm, then assume
Class 1: not wet above 150 cm.
SECTION III: SITE CHARACTERISTICS
A. Parent Material
16
Contestants must identify the parent material(s) within each profile. If more than one
parent material is present, all should be recorded. Parent material classifications in this
region can sometimes be difficult to interpret in transition areas. Landscape position and
associations, the soil profile, presence or absence of polished sedimentary rock, percent
slope, and proximity to large streams should all be considered in determining parent
material classification.
(1) Alluvium: Alluvium is material transported and deposited by flowing water or in
ponded depressions. It includes material on flood plains, stream terraces, alluvial
fans, and at the base of slopes, drainage ways and depressions. Water is the primary
mechanism of transport. Evidence of sorting by flowing water (stratification) may
occur in several forms, including irregular variability of particle size with depth,
especially of sand and rock fragment sizes. For example, thin strata (layers) of sandy
textures alternating with silty textures, or a change from non-gravelly to extremely
gravelly textures indicate irregular deposition due to variation in the velocity of
flowing water. Rounded rock fragments sorted by size are also clues of movement
by flowing water. In flooded areas, the soil may contain buried horizons and is
coarser-textured nearest the active channel, becoming finer-textured away from the
channel.
For the purposes of this contest, alluvium refers to soils that are
excessively drained to poorly drained, loamy and clayey soils that formed on natural
levees and in back swamps in sediment chiefly from the Arkansas and Mississippi
Rivers and associated tributaries.
(2) Colluvium: Colluvium is poorly sorted material accumulated on, and especially at
the base of, hill slopes. Typically, colluvium in the region is found on hill slopes
with grades greater than 8% and lengths greater than 100 m. Colluvium results from
the combined forces of gravity and water in the local movement and deposition of
materials. Colluvium may contain a mixture of rock fragment types with variable
size and orientation within a horizon, or it may contain a mismatch between rock
fragments in upper horizons with those of horizons below that retain rock-controlled
structure or in-place rock fragments below.
Recently transported colluvium is
typically found on backslope, footslope or toeslope slope profiles.
17
(3) Loess: Fine-grained, wind-deposited materials that are dominantly of silt size.
Textures are usually silt loam, silt, or silty clay loam. Where loess mantles are thin
(< 75 cm), there may be some coarser mineral particles particularly toward the base
of the loess deposit.
Larger particles (including coarse fragments) may be
incorporated the loess mantle through bioturbation.
(4) Marine: Soils that formed in sediments of marine origin; laid down in the waters of
an ocean. For this contest, marine parent materials are typically soils that formed in
uplands in sediment deposited in old coastal embayments and in local sediment
washed from these uplands. They are typically moderately well to poorly drained
loamy soils that formed in stratified sediment deposited on the bottom of shallow
coastal embayment that covered the region many thousands of years ago, and in
recent alluvium washed from this material.
(5) Residuum:
The unconsolidated and partially weathered mineral materials
accumulated by disintegration of bedrock in place.
B. Landform
(1) Depression: For the purpose of this contest, a depression is considered to be shallow
depressions less than 0.5 ha in area showing no visible signs of developed surface
outlets for runoff.
(2) Floodplain: The lowest geomorphic surface which is adjacent to the stream bed and
which floods first when the stream goes into flood stage. It is formed by the
deposition of alluvium. Each stream has only one floodplain.
(3) Stream Terrace: These are geomorphic surfaces of varying age formed by the
deposition of alluvium and are higher in elevation than the flood plain. A stream
may have more one or more terraces.
(4) Mound: A low, rounded natural hill of unspecified origin. Found on flat lying
geomorphic surfaces older than late Holocene, usually old fluvial terraces and
normally between 0.5 – 2.0 m in height and 10 and 30 m in diameter. The origin
of these ‘pimple’ mounds is uncertain. Hypotheses suggested include erosion,
18
gophers, coppice dunes formed in past droughts, seismic, and others. For the
purpose of this contest, mound/intermound areas will contain many obvious
mounds.
(5) Inter-Mounds: The concave to relatively flat-bottomed, irregularly shaped
depressions that separate pimple mounds in mounded landscapes.
(6) Uplands: Areas dominated by residual and colluvial parent material which usually
are found above floodplains and stream terraces. The bulk of soil material found
in uplands is produced by physical and chemical weathering of parent material in
place and mass wasting such as soil creep, debris and mud-flows, slumps,
landslides, and other erosional depositions.
C. Slope
Slope classes used in this contest are listed on the scorecard. The slope should be
determined with an Abney level or clinometer between two stakes at each site. The
stakes may be of unequal height. Stakes are provided to assist contestants to measure the
actual slope of the land between the stakes, not the slope at the top of the stakes. The
height of the stakes should be compared and the actual soil slope measured.
D. Slope Profile
The slope profile components are shown graphically by hill slope cross-sections in
Figures 1 and 2. Not all profile elements may be present on a given hill slope. When
possible slope stakes will be positioned to define the slope profile, but in some cases the
slope profile may extend beyond the slope stakes. Contestants should consider the area
that includes the soil pit and slope stakes when evaluating slope profile.
(1) Summit: a topographic high such as a hilltop or ridge top. Summits can be linear or
slightly convex in shape.
(2) Shoulder: a slope adjacent to the summit that is convexly rounded.
(3) Backslope:
a mostly linear surface that extends downward from a summit or
shoulder position.
19
(4) Footslope: a concave slope segment at the base of a hill slope. If located in a
closed depression center that is concave in shape, footslope should be marked.
(5) Toeslope: the lowest component that extends away from the base of the hill slope.
Toeslopes are typically linear in shape. If located in a closed depression center that
is linear in shape, toeslope should be marked.
(6) None: This designation will be used when the slope at the site is < 2% AND the site
is not in a well-defined example of one of the slope positions given above (e.g.,
within a nearly level, terrace, or floodplain).
Figure 1. Landscape designations for landscapes with a defined drainageway.
Figure 2. Landscape designations for closed depression landscapes.
E. Surface Runoff
Runoff is the water that flows away from the soil over the surface without infiltrating.
Soil characteristics, management practices, climatic factors (e.g., rainfall intensity),
vegetative cover, and topography determine the rate and amount of runoff. The scorecard
includes the six runoff classes and the combined effects of hydraulic conductivity, slope,
and vegetation on runoff rate are considered. A guideline for evaluating various slopes
and limiting hydraulic conductivity under cultivated conditions follows. If the surface
has a dense vegetative or debris cover, the surface runoff class should be assigned one
20
lower class rate to a minimum of ‘Very Slow’.
If the soil is located in a closed
depression use the “closed depression” row in the table.
Limiting hydraulic conductivity
of the surface horizon
% Slope
High
Moderate
Low
Closed
depression
Ponded
Ponded
Ponded
0 - <1
Very slow
Very slow
Slow
1 -<2
Very slow
Slow
Medium
2-<6
Slow
Medium
Rapid
6 - < 12
Medium
Rapid
Very rapid
12+
Rapid
Very rapid
Very rapid
F. Soil Erosion Potential
The erosion potential is dependent on the factors contributing to surface runoff, as well as
organic matter content and physical properties of the surface horizon, including texture
and structure. For the purposes of this contest, the soil erosion potential will be determined
from the surface texture and surface runoff according to the following table.
Surface Horizon Texture
Surface Runoff
S, LS
SCL, SC
SL, CL, C, SIC
L, SI, SIL,
Ponded/Neg.
Low
Low
Low
Very slow
Low
Low
Low
Low
SICL
Medium
Slow
Low
Low
Medium
Medium
Medium
Low
Low
Medium
High
Rapid
Low
Medium
High
High
Medium
High
High
High
Very Rapid
21
SECTION IV: SOIL CLASSIFICATION
A simplified taxonomic key (Appendix 3) should be used for determining the soil SubOrder and Great Group. This will NOT be provided to the students in competition. Soil
Taxonomy, USDA-NRCS Agricultural Handbook 436, 2nd Edition (1999) and the most
current edition of Keys to Soil Taxonomy should be referred to for criteria used for other
soil details for classification purposes, such as soil Order. The Family Particle Size
Class(es) should be determined from the Family Particle Size Control Section as defined
in the most current edition of Keys to Soil Taxonomy. Generally, the control section for
most soils in the region is between the lower boundary of the Ap horizon or a depth of 25
cm below the mineral soil surface, whichever is deeper, and the shallower of the
following: (a) a depth of 100 cm below the mineral soil surface, (b) a fragipan, petrocalcic,
petrogypsic, or placic horizon, if between 36 and 100 cm below the mineral soil surface,
or (c) the argillic or natric horizon if 50 cm or less thick, or the upper 50 cm of the horizon
if >50 cm thick. Should strongly contrasting particle-size classes exist, as defined by the
most current edition of Keys to Soil Taxonomy, students should mark a ‘1’ indicating the
upper class and a ‘2’ to indicate the lower class. For example, sandy over clayey should
have a ‘1’ marked for sandy and a ‘2’ marked for clayey. Partial credit (2 pts) will be
awarded if only one of the strongly contrasting particle-size classes is marked. NO points
will be awarded if the correct classes are identified but numbered incorrectly!
Contestants should list only the diagnostic horizons of the soil to be classified. In the case of
buried soils, only the diagnostic horizons (or lack thereof) present above the buried soil
should be selected on the scorecard and used to determine taxonomic classification. For
example, if a soil contains a horizon sequence of A(ochric)-C1-C2-Ab-Btb(argillic) and the
Ab and Btb horizons meet the definition of a buried soil, the correct answers would be
"ochric" under epipedon and "none" under subsurface diagnostic feature. If argillic was
selected under diagnostic horizons, it would be incorrect. Pertinent laboratory data and other
information will be provided for each soil on the pit card. This information will be used to
determine the correct epipedon, subsurface horizon or feature, order, suborder, and great
group for each soil. For taxonomic decisions, assume that the last horizon extends to 2 m or
more unless it is directly underlain by a lithic or paralithic contact, or unless additional
22
information is provided on the site card. Assume that saturation, if present, is endo if all the
layers from the upper boundary of saturation to a depth of 200 cm or more from the mineral
soil surface show evidence of water saturation. If the soil is saturated with water in one or
more layers within 200 cm of the mineral soil surface, but also has one or more unsaturated
layers, with an upper boundary above a depth of 200 cm, below the saturated layer (eg., the
zone of saturation is perched on top of a relatively impermeable layer), the saturation is epi.
Dry colors of surface horizons may be provided at some or all sites for help in making
taxonomic decisions. If dry colors are not provided, taxonomic decisions should be based
solely on moist color.
SECTION V: SOIL INTERPRETATIONS
A. Interpretations for dwellings with basements, onsite wastewater loading rates, septic
tank absorption field, and local roads and streets.
Contestants will be expected to recognize soil limitations relative to dwellings with
basements, determine onsite wastewater loading rates and suitability for septic tank
absorption fields, and limits for local roads and streets. The tables in Appendix 4 have been
modified from similar tables in the National Soils Handbook and are guides to making soil
interpretations for these uses. A copy will be provided to each contestant. When utilizing
the following tables the overall degree of limitation is determined by the most restrictive soil
property which is determined first when reading the table from top to bottom. Some instances
may occur where the pit does not extend to the necessary depth needed to make the
interpretation. In these cases contestants must assume the lowest horizon if the pit extends to
the interpretative depth unless a lithic or paralithic contact occurs within the depth to be
judged.
Special considerations for soil/site interpretations:

Fragipans (e.g. Btx horizons) are not considered a cemented pan for interpretations
for local roads and streets.
23

When rating shrink-swell suitability for houses with basements, consider the
continuous thickness of clay textures (SC, SIC, and C). For example, if a profile has
an 8cm thick horizon of SIC overlying a 15 cm horizon of C, the continuous thickness
of clay is 23 cm, and the site should be rated severe for reason #7, Shrink swell
(assuming it was not rated severe by any of the reasons above it in the table).

For interpretation of Local Roads and Streets (frost action), consider the texture of the
most restrictive horizon within the profile or depth specified.

When average texture is specified (Local Roads and Streets-strength), use the
weighted average texture based on sand and clay contents of horizons within the
depth specified.
B. Determination of on-site wastewater loading rates.
Contestants will determine the on-site wastewater loading rates using soil criteria established
by the Arkansas Health Department with slight modifications for this contest. The method
involves estimating the depth to seasonal water tables of three durations for two hydraulic
conductivity classes using the guides described in Appendix 5 and modified, if needed, as
described below. Hydraulic conductivity class is determined as the most limiting class in the
upper 50 cm. Soils with a low HC in the upper 50 cm are not suited for standard on-site
disposal systems and are assigned a loading rate of 0 gpd/ft2. The interpretations relate
primarily to redoximorphic features and clay content. All colors are for moist conditions. To
determine the on-site wastewater loading rates:
1) determine if the redoximorphic features have dissimilar color patterns on ped surface and
ped interiors, or similar color patterns on ped surfaces and ped interiors and horizons without
peds.
2) find the depths to the ‘brief’, ‘moderate’, and ‘long’ SWT (if present) using the criteria in
Appendix 5. A copy of Appendix 5 and 6 will be provided to each contestant.
3) If more than one SWT duration is present, adjust the depths to the moderate SWT and the
long SWT as described below.
24
To adjust the Moderate SWT, subtract the depth to the brief SWT from the depth to the
moderate SWT and divide by 3. Subtract the result from the depth to the moderate SWT to
obtain the adjusted moderate SWT.
To adjust the long SWT if a moderate SWT is present, subtract the adjusted moderate SWT
from the depth to the long SWT and divide by 2. Subtract the result from the depth to the
long SWT to obtain the adjusted long SWT.
To adjust the long SWT where only a brief SWT and a long SWT is present, subtract the
depth to the brief SWT from the long SWT and divide by 6. Subtract the above number from
the depth to the long SWT to obtain the adjusted long SWT.
4) Compare the loading rates for the brief, adjusted moderate, and/or adjusted long SWT’s
using the soil loading charts (Appendix 6). Use the most restrictive (lowest) loading rate to
determine the on-site wastewater loading rate. Soils that only have one duration of seasonal
water table are loaded by using the loading rate given in the soil loading charts for the
duration of seasonal water table observed. Examples of typical scenarios are below.
Example 1. The soil has a brief SWT at 45 cm, moderate SWT at 61 cm, long SWT at 84
cm, and a moderate HC at 50 cm. Adjusted moderate SWT = 61 - ((61-45)/3) = 61- (16/3)
= 61 – 5 = 56 cm. Adjusted long SWT = 84 – ((85-56)/2) = 84 – (29/2) = 84 – 15 = 69
cm. The loading rates (Appendix 6) for this soil are: brief SWT = 0.75 gpd/ft2, adjusted
moderate SWT = 0.44 gpd/ft2, and adjusted long SWT = 0.34 gpd/ft2. The most restrictive
loading rate is 0.34 gpd/ft2 and therefore the correct answer on the score card is 0.26-0.50
gpd/ft2.
Example 2. The soil has a brief SWT at 56 cm, no moderate SWT is observed, a long SWT
at 95 cm, and a moderate HC at 50 cm. The adjusted long SWT = 95 – ((95-56)/6) = 95 –
(39/6) = 95 – 7 = 88 cm. The loading rates (Appendix 6) for this soil are brief SWT = 0.75
gpd/ft2, adjusted long SWT = 0.53 gpd/ft2. The most restrictive loading rate is 0.53 gpd/ft2
and therefore the correct answer on the score card is 0.51-0.75 gpd/ft2.
Example 3. No brief SWT is observed, a moderate SWT is at 71 cm, a long SWT at 102 cm,
and a moderate HC at 50 cm. It will not be necessary to adjust the moderate SWT since no
brief SWT is present, however the adjusted long SWT = 102 – ((102-71)/2) = 102 – (31/2)
25
= 102 – 16 = 86 cm. The loading rates (Appendix 6) for this soil are moderate SWT =
0.73, adjusted long SWT = 0.50 gpd/ft2. Therefore, the correct answer on the score card is
0.26-0.50 gpd/ft2.
Example 4. The soil has a clay content >35% at 50 cm. The HC of this soil therefore is
LOW in the loading zone of 51 cm and a loading rate of 0 gpd/ft2 is used (see footnote,
Appendix 6). Therefore, the correct answer on the score card would be 0-10 gpd/ft2.
26
Appendix 1
Example of the Site Card
Site No. ______1_______
Describe _________ horizons to a depth of _________cm.
The marker is somewhere in the third horizon at _________ cm.
†
Horizon
1
2
3
4
5
6
% B.S.
% Organic C
%CaCO3†
E.S.P.ŧŧ
Dry Color†
These values may or may not be included depending upon the site and conditions.
E.S.P = Exchangeable Sodium Percentage. This value may or may not be included depending upon the site
and conditions.
ŧ
Vicinity Map
27
Appendix 2
Official Abbreviations and USDA Texture Triangle
Boundary Distinctness:
Abrupt - A
Clear - C
Gradual - G
Diffuse - D
Coarse Fragments:
Gravelly
Very Gravelly
Extremely Gravelly
-GR
-VGR
-XGR
Cobbly
-CB
Very Cobbly
Extremely Cobbly
Texture:
Coarse sand
Sand
Fine sand
Very fine sand
Loamy coarse sand
Loamy sand
Loamy fine sand
Loamy very fine sand
Coarse sandy loam
Sandy loam
Clay
-COS
-S
-FS
-VFS
-LCOS
-LS
-LFS
-LVFS
-COSL
-SL
-C
Fine sandy loam
Very fine sandy loam
Loam
Clay loam
Silt
Silt loam
Silty clay loam
Silty clay
Sandy clay loam
Sandy clay
Structure Grade:
Weak – 1
Moderate – 2
Structure Shape:
Granular
-GR
Platy
-PL
Prismatic
-PR
Columnar
-CO
Wedge
-W
Consistency:
Loose
-L
Very Friable - VFR
Friable
-F
Strong – 3
-VCB
-XCB
-FSL
-VFSL
-L
-CL
-SI
-SIL
-SICL
-SIC
-SCL
-SC
Structureless – 0
Angular Blocky
Subangular Blocky
Single grain
Massive
Firm
Very Firm
Extremely Firm
-ABK
-SBK
-SG
-M
- FI
- VFI
- EFI
28
USDA Texture Triangle
29
Appendix 3
Simplified Key to Soil Sub-Order and Great Group
Alfisols
Suborder: Alfisols that:
1) Have a seasonally high water table within 50 cm ------------------------------------------------------ Aqualfs
39TU
U39T
Note: Redox features are evidence of a seasonal high water table. Artificially drained
sites are included in the Aqualfs.
C
2) Other Alfisols with seasonally well distributed precipitation --------------------------------------- Udalfs
Note: These soils have a udic soil moisture regime.
39TU
U39T
3) Have somewhat limited soil moisture available for plant growth. -------------------------------- Ustalfs
Note: These soils have an ustic soil moisture regime. Moisture is limited, but available
during portions of the growing season.
39TU
U39T
Albaqualfs - These soils have ground water seasonally perched above a slowly permeable clay-enriched
argillic horizon. Commonly, a light-colored, leached, albic horizon rests abruptly on the argillic subsoil
horizon, with virtually no transitional horizon between the two. There is a significant difference in clay
content immediately above and below the top of the argillic horizon. In the United States, most Albaqualfs
have a mesic, thermic, or hyperthermic temperature regime and, unless the soils are irrigated, the albic
horizon is dry for short periods in summer in most years. The dryness seems essential to the genesis.
Thus, Aqualfs in which the albic horizon is rarely dry are in great groups other than Albaqualfs.
Fragiaqualfs - These soils have a dense, brittle layer (fragipan) within 100 cm of the mineral soil surface.
Most have ground water that is perched above the fragipan at some period and saturates the soils at
another period. In the United States, the soils generally have frigid to thermic temperature regimes. In
most years, the albic horizon generally does not become dry, but the ground water drops below the base
of the fragipan during summer and the soil moisture content is below field capacity at some period. Most
Fragiaqualfs in the United States formed in Wisconsinan deposits of late-Pleistocene age and had
broadleaf deciduous forest vegetation before they were cultivated. Most of the soils are nearly level.
Fragiaqualfs as a group have lower base saturation than other Aqualfs.
Epiaqualfs – Have a perched water table. Ground water is commonly perched on horizons below the top
of the argillic horizon, but it does not saturate the lower part of the profile. It fluctuates from a level near
the soil surface to below the argillic subsoil horizon and sometimes is not evident. Before cultivation, most
Epiaqualfs supported either deciduous broadleaf or coniferous forest. Generally, Epiaqualfs are nearly
level, and their parent materials are typically late-Pleistocene sediments.
Endoaqualfs – Are saturated throughout the profile for some time during the year. The ground water
fluctuates from a level near the soil surface to below the argillic subsoil horizon and is sometimes below a
depth of 200 cm. Before cultivation, most Endoaqualfs supported either deciduous broadleaf or
coniferous forest. Generally, they are nearly level, and their parent materials are typically late-Pleistocene
sediments.
Fragiudalfs - These soils have a fragipan (compact and brittle, but not cemented) within 100 cm of the
soil surface. They commonly have an argillic (clay accumulation) or cambic (minimal soil development)
subsoil horizon above the fragipan. Redoximorphic features (gray and red mottled color pattern) are in
many pedons, starting at a depth 50 to 100 cm. Ground water is perched seasonally above the fragipan,
and a thin eluvial horizon commonly is directly above the fragipan. Most Fragiudalfs in the United States
are on gentle slopes and formed, at least in part, in silty or loamy deposits. The deposits are largely of
late-Pleistocene age. The duripan formed in an older buried soil in some areas. A duripan seems to form
if the burial was to a depth of about 50 to 75 cm. Temperature regimes are mostly cold to warm. In the
United States, the native vegetation on these soils was primarily a broadleaf deciduous forest.
30
Paleudalfs - These soils have a thick solum. Some have an argillic subsoil horizon (clay accumulation)
that shows evidence of destruction in the form of a glossic horizon. Paleudalfs are on relatively stable
surfaces. Most of them are older than the Wisconsinan Glaciation. The time of soil formation dates from
the Sangamon interglacial period or earlier. Base saturation commonly is lower than that in many other
Alfisols. Before cultivation, most Paleudalfs in the United States had a vegetation of mixed deciduous
hardwood forest.
Glossudalfs - These soils have an argillic subsoil horizon (clay accumulation) that shows evidence of
destruction in the form of a glossic horizon. The glossic horizon extends through the argillic horizon in
some of these soils. They are more extensive in Europe than in the United States.
Hapludalfs – These soils have an argillic subsoil horizon (clay accumulation) that normally extends to
less than 150 cm below the soil surface. In many areas, it is less than 100 cm below the surface. In an
undisturbed soil, there generally is a thin, very dark brown A horizon, 5 to 10 cm thick, over a lighter
colored brownish eluvial horizon. The eluvial horizon grades into a finer textured argillic horizon, generally
at a depth of about 30 to 45 cm in loamy materials. Because the Hapludalfs have been cultivated
extensively, many of those on slopes have lost their eluvial horizons through erosion. These soils formed
principally in late-Pleistocene deposits or on a surface of comparable age. They are extensive soils in the
Northeastern States, excluding New England, and in Europe, excluding most of Scandinavia. The
vegetation on Hapludalfs in the United States was deciduous broadleaf forest, but the soils are now
mostly farmed. Temperature regimes are mesic or thermic.
Natrustalfs - These soils have a natric subsoil horizon (high levels of illuvial clay and sodium). The
epipedon is normally 10 to 20 cm thick. The natric horizon generally is underlain by a layer with calcium
carbonate accumulations at a depth between about 25 and 40 cm. Except for a few parts of the Great
Plains and mountain basins, they are not extensive in the United States.
Paleustalfs - Are the reddish or red Ustalfs that are on old surfaces. Many of them have some plinthite
(iron-rich concentration that irreversibly hardens after exposure to repeated wet-dry cycles) in their lower
horizons. Paleustalfs occur in relatively stable landscape positions, their slopes are mostly gentle, and
their genesis began before the late Pleistocene. In the United States, they typically have a horizon with
accumulations of calcium carbonate in or below the argillic horizon as a result of additions of atmospheric
carbonates. Commonly, secondary lime coats the surfaces of peds that have noncalcareous interiors and
the soils may be noncalcareous at a depth of less than 200 cm. A few of these soils, near the boundary
where they join Aridisols, have received enough calcareous dust to have a petrocalcic horizon (cemented
by carbonates). A few others, near the boundary where they join Udults or Udalfs, do not have
accumulating carbonates. Before cultivation, the vegetation on the Paleustalfs in the United States
included a mixture of grasses and woody plants. These soils are moderately extensive in the southern
part of the Great Plains in the United States.
Haplustalfs - These soils have a relatively thin argillic subsoil horizon (clay accumulation). Many of these
soils are relatively thin, are reddish to yellowish brown, or have a significant clay decrease within 150 cm
of the surface. Haplustalfs are commonly in areas of relatively recent erosional surfaces or deposits, most
of them late Pleistocene in age. Some of the soils have a monsoon climate. Others have two more or less
marked dry seasons during the year.
Entisols
Suborder: Entisols that:
1. Have a seasonally high water table within 50 cm ----------------------------------------------------- Aquents
Note: Artificially drained soils are included in Aquents. See Keys to Soil Taxonomy
for specific details regarding required depths, presence of sulfidic materials, presence
of a reduced matrix (exhibits color change upon exposure to air), and various
texture/color combinations characteristic of Aquents.
39TU
U39T
31
2. Have sandy texture throughout the upper 100 cm ---------------------------------------------- Psamments
Note: Psamments have < 35% rock fragments. Required depth of sandy textures
is less in profiles with bedrock above 100 cm.
39TU
U3 9T
2. Consist of stratified alluvial deposits, with irregular carbon content with depth....... Fluvents.
3. Other simple Entisols not listed above .......................................................................... Orthents
Psammaquents - These soils have a sandy texture and commonly are gray, with or without
redoximorphic concentrations (reddish to black accumulations of iron-manganese oxides). Most of these
soils formed in late-Pleistocene to recent sediments. Most do not have distinctive features, but a few have
a weakly developed subsoil horizon that is similar to the one in Spodosols. Others show some darkening
and accumulation of organic matter in the surface layer.
Fluvaquents – These are primarily the stratified, wet soils on flood plains and deltas of middle and low
latitudes. The stratification reflects deposition of sediments under changing currents and in shifting
channels. The sediments are of Holocene age and have a relatively high content of organic carbon at a
considerable depth when compared with many other wet, mineral soils. The materials have dried or have
partially dried from time to time as they accumulated, and are therefore not fluid when wet. These soils
are extensive along large rivers, particularly in humid areas. Generally, Fluvaquents are nearly level.
Epiaquents - These soils have ground water that is perched during some periods and fluctuates from a
level near or above the soil surface in wet seasons. Many Epiaquents support either a deciduous or a
coniferous forest. Some have been cleared and are used as cropland or pasture. Generally, Epiaquents
are nearly level, and their parent materials are typically late-Pleistocene or Holocene sediments.
Endoaquents – These soils are saturated throughout the profile for some time during the year. Many
Endoaquents support either a deciduous or coniferous forest. Some have been cleared and are used as
cropland or pasture. Generally, Endoaquents are nearly level, and their parent materials are typically latePleistocene or Holocene sediments.
Quartzipsamments - These are the freely drained Psamments that have more than 90% resistant
minerals. They are in humid to semiarid, cool to hot regions. These soils are high in content of quartz
sand and are white or stained with shades of brown, yellow, or red. Because they have virtually no
minerals that can weather, they can occur on some extremely old land surfaces. They also occur on latePleistocene and younger surfaces. The vegetation on Quartzipsamments varies widely with climate.
Where cultivated, supplemental water and nutrient needs can be high. Quartzipsamments are extensive
on the coastal plains in the United States.
Udipsamments - These are the Psamments that are of humid regions. Precipitation is distributed
throughout the year. They are predominantly in areas of late-Pleistocene or more recent deposits and are
mostly brownish and freely drained. Most of the soils have supported forest vegetation, but a few have
been cultivated ever since the sands were deposited. Others have been cultivated for a very long time.
Udipsamments are extensive in the United States.
Ustipsamments - These are the Psamments that have an ustic moisture regime. Although moisture is
limited, it is generally available during portions of the growing season. Temperatures range from cool to
hot. These soils support mostly grass or savanna vegetation. A few are in drought-tolerant forests of
small, scattered trees. Many support as much or more vegetation as other soils with an ustic moisture
regime, perhaps because rapid infiltration results in little or no precipitation being lost to runoff.
Ustipsamments are used mainly for grazing. Few of them are cultivated because they are subject to soil
blowing if they are cultivated. Ustipsamments are extensive soils on the Great Plains in the United States.
32
Udifluvents – These soils have a udic moisture regime with precipitation distributed throughout the year.
Temperatures range from cool to hot. Udifluvents are on flood plains along streams and rivers, and they
may be flooded during almost any season. There is little or no evidence of alteration of the fine
stratification in the alluvium, although in some Udifluvents, especially those with finer textures, identifying
the stratification may be difficult. Some Udifluvents formed under forest vegetation, but many have had no
vegetation other than pasture or cultivated crops because the sediments in which the soils formed were
deposited while the soils were being used. Udifluvents are extensive in the United States.
Ustifluvents – These soils have an ustic moisture regime. Although moisture is limited, it is generally
available during portions of the growing season. Temperatures range from cool to hot. These soils are on
flood plains along rivers and streams in areas of middle or low latitudes. Flooding can occur in any
season but is most common in summer in the middle latitudes and during the rainy season in the Tropics.
A few of the soils are flooded regularly in summer because of melting snow in high mountains, even
though the summer is rainless.
Udorthents - Orthents that have a udic moisture regime with precipitation distributed throughout the year.
Temperatures range from cool to hot. Generally, they are acid to neutral, but some are calcareous.
Slopes generally are moderate to steep but are gentle in a few areas. Udorthents commonly occur in
areas of very recently exposed regolith, such as loess or till; in areas of weakly cemented rocks, such as
shale; or in areas of thin regolith over hard rocks. Many of the gently sloping soils are the result of mining
or other earth-moving activities. The vegetation is commonly a deciduous forest, or the soils are used as
pasture. Udorthents are extensive soils on steep slopes in the humid parts of the United States.
Ustorthents - Orthents of cool to hot regions. They have an ustic moisture regime. Although moisture is
limited, it is generally available during portions of the growing season. Generally, they are neutral to
calcareous, but some are acid. Slopes are mostly moderate to steep but are gentle in a few areas.
Ustorthents commonly occur in areas of very recently exposed regolith, mostly weakly cemented
sedimentary deposits or in areas of thin regolith over hard rocks. The vegetation in warm regions
commonly is a deciduous forest or savanna. The soils that have a cooler temperature regime commonly
support scattered grasses mixed with xerophytic shrubs. Ustorthents are extensive in the United States,
particularly on the Great Plains.
Inceptisols
Suborder: Inceptisols that have:
1. Either:
a. A seasonally high water table within 50 cm
Note: This item requires either a histic epipedon (wet, organic surface layer), a sulfuric horizon within 50
cm (highly acid due to oxidation and production of sulfuric acid), or redoximorphic features within 50 cm
(gray and red color patterns. See Keys to Soil Taxonomy for specific colors required).
OR
b. A seasonal high water table within 100 cm and high levels of
sodium within 50 cm -------------------------------------------------------------------------------------- Aquepts
39TU
U39T
2. Seasonally well distributed precipitation ----------------------------------------------------------------- Udepts
(Note: These soils have a udic soil moisture regime.)
39TU
U39T
3. Somewhat limited soil moisture available for plant growth ---------------------------------------- Ustepts
Note: These soils have an ustic soil moisture regime. Moisture is limited, but available
during portions of the growing season.
39TU
U39T
Fragiaquepts - These soils have a fragipan (firm and brittle, but not cemented) within 100 cm, commonly at a depth
of 30 to 50 cm. Typically the water table is perched on the fragipan. The horizons above the pan are grayish and are
saturated with water during some periods in most years. Most of these soils have forest vegetation, but a few areas
have been cleared. The trees have a shallow root system and are particularly subject to windthrow. A distinct
33
microrelief of 50 to 60 cm or more is very common above the pan. The upper surface of the pan generally is smooth.
In many areas of these soils, the horizons above the fragipan appear to have been mixed by the uplift of the roots of
falling trees. In some areas the horizons above the pan consist of an organic O horizon, an ochric epipedon (typically
thin and/or light-colored), and an intermittent cambic subsoil horizon (minimal soil development) below the
mounds. In other areas the cambic horizon is continuous. The Fragiaquepts in the United States are mostly in areas
with cool to moderate temperatures. They are moderately extensive in parts of the Northeastern States, and a few of
the soils occur in Oregon and Washington. Most Fragiaquepts are nearly level or gently sloping and developed in
Pleistocene-age sediments.
Epiaquepts - These soils have a perched water table (episaturation). The ground water commonly fluctuates from a
level near the soil surface to below a depth of 200 cm. These soils have cool to warm soil temperature. Before
cultivation, most Epiaquepts supported forest vegetation. Generally, Epiaquepts are nearly level or gently sloping,
and their parent materials are typically late-Pleistocene or younger sediments.
Endoaquepts – These soils are saturated throughout the profile for some time during the year (endosaturation). The
ground water commonly fluctuates from a level near the soil surface to below a depth of 50 cm. These soils have
cool to warm soil temperature. Before they were cultivated, most Endoaquepts supported forest vegetation.
Generally, Endoaquepts are nearly level, and their parent materials are typically late-Pleistocene or younger
sediments.
Fragiudepts - These soils have a fragipan (firm and brittle, but not cemented) within 100 cm. Commonly, they have
a brownish cambic subsoil horizon (minimal soil development) that is underlain, at a depth of about 50 cm, by the
fragipan. Most Fragiudepts have perched water above the pan at some time of the year, and few roots penetrate the
pan. Consequently, plants tend to have shallow root systems. Many Fragiudepts formed in late-Pleistocene or
Holocene deposits on gentle or moderate slopes. Some are strongly sloping. The parent materials of most
Fragiudepts are loamy and either are acid or have only a small amount of free carbonates. A few of the materials are
sandy and have an appreciable amount of fine sand and very fine sand. Most of the Fragiudepts in the United States
are in the Northeastern States and the States bordering the Mississippi and Ohio Rivers. A few are in the northern
Lake States, and some are in the humid parts of the Northwestern States. These soils are extensive.
Dystrudepts – These are acid soils of humid regions, generally low in natural fertility. They developed mostly in
late-Pleistocene or Holocene deposits. Some developed on older, steeply sloping surfaces. The parent materials
generally are acid, moderately or weakly consolidated sedimentary or metamorphic rocks or acid sediments. A few
of the soils formed in saprolite derived from igneous rocks. The vegetation was mostly deciduous trees. Most of the
Dystrudepts that formed in alluvium are now cultivated, and many of the other Dystrudepts are used as pasture. The
normal horizon sequence in Dystrudepts is an ochric epipedon (typically thin and/or light-colored) over a cambic
subsoil horizon (minimal soil development). Some of the steeper Dystrudepts have a shallow, root-restrictive contact
with bedrock or other compact, dense material. Dystrudepts are extensive in the United States. They are mostly in
the Eastern and Southern States.
Dystrustepts - These are the acid Ustepts with low base saturation and relatively low natural fertility. They
developed mostly in Pleistocene or Holocene deposits. Some of the soils that have steep slopes formed in older
deposits. The parent materials generally are acid, moderately or weakly consolidated sedimentary or metamorphic
rocks or acid sediments. The vegetation was mostly forest. Most of these soils have warm or very warm temperature.
A common horizon sequence in Dystrustepts is an ochric epipedon (typically thin and/or light-colored) over a
cambic subsoil horizon (minimal soil development). Some of the steeper soils are shallow to root-limiting bedrock
or a dense, compact layer. In the United States these soils are found mostly in coastal California and in Hawaii. A
few are in the Rocky Mountains or Great Plains.
Haplustepts - These are the more or less freely drained Ustepts that are calcareous at some depth or have a high
base saturation. They commonly have an ochric epipedon (typically thin and/or light-colored) over a cambic subsoil
horizon (minimal soil development). Some of the soils have an accumulation of calcium carbonate in the subsoil.
The native vegetation commonly was grass, but some of the soils supported trees. Haplustepts in the United States
are mostly on the Great Plains.
34
Mollisols
Suborder: Mollisols that have:
1. A seasonally high water table within 100 cm, a light-colored leached
layer (albic horizon), and an argillic (clay accumulation) or natric (high
levels of illuvial clay and sodium) horizon ---------------------------------------------------------------- Albolls
39TU
U39
2. A seasonally high water table within 50 cm ...................................................... Aquolls(Note:
Redoximorphic features are evidence of a seasonal high water table. However, the intense accumulation of organic
matter results in very dark colors that often mask the morphology of reddish and grayish colors associated with
redoximorphic features. Artificially drained soils are included in Aquolls and Albolls.)
3. Seasonally well distributed moisture regime .................................................................................. Udolls
(Note: these soils have a udic moisture regime.)
4. Somewhat limited soil moisture available for crop growth ........................................................... Ustolls
(Note: these soils typically have a ustic moisture regime. Moisture is limited, but available during portions of the
growing season.)
Argialbolls - These soils have an argillic subsoil horizon (clay accumulation). Most of the soils have very dark gray
to black coatings of humus and clay on the peds in the upper part of the argillic horizon. In the United States, these
soils are most extensive in the loess-covered areas of the Midwestern States where the temperature regime is mesic.
A very few of the soils have a frigid or thermic temperature regime. A distinct moisture deficit in summer and a
moisture surplus in winter and spring seem to be essential to the genesis of these soils. Argialbolls are associated on
the landscape with soils of all other suborders of Mollisols, except possibly for Rendolls. Because they have gentle
slopes, most of the Argialbolls in the United States are cultivated.
Natralbolls - These soils have a natric subsoil horizon (high levels of illuvial clay and sodium). The natric horizon
normally lies very close to the surface. These soils commonly have a thin dark surface layer overlying the lightcolored, leached albic horizon. The color of the upper part of the soils, after mixing to a depth of 18 cm, however, is
dark enough for a mollic epipedon because both the epipedon and the natric horizon are dark-colored. Ground water
is shallow during part of the year, and capillary rise in many Natralbolls has concentrated salts, including sodium
salts, in the upper 50 cm of the soils. Natralbolls are known to occur only in subhumid and humid regions. They are
in areas of late-Pleistocene till plains and lacustrine deposits or Holocene deposits.
Argiaquolls - These soils have an argillic subsoil horizon (clay accumulation). In these soils the depth to ground
water fluctuates appreciably and commonly is shallow in winter and spring but deep in summer. Most of the
Argiaquolls in the United States have been drained and are used as cropland. They are extensive and are widely
distributed throughout the Midwest and the western parts of the country.
Epiaquolls - These soils have episaturation. A perched water table is at or near the soil surface during wet periods,
mostly in winter and early spring, but commonly does not occur during dry periods in summer. The depth to ground
water fluctuates appreciably in these soils. Most of the Epiaquolls in the United States have some artificial drainage,
mostly surface drainage, and are used as cropland. The soils are extensive and are widely distributed throughout the
Midwest and the western parts of the country.
Endoaquolls - These soils have endosaturation. They are saturated throughout the profile at some time. The depth to
ground water fluctuates appreciably in these soils. Commonly, the ground water is at or near the soil surface in
winter and spring but is deep in summer. Most of the Endoaquolls in the United States have been artificially drained
and are used as cropland. They are extensive and are widely distributed throughout the Midwest and the western
parts of the country.
35
Natraquolls - These soils have a natric subsoil horizon (high levels of illuvial clay and sodium) that normally lies
very close to the surface. The thin overlying horizon commonly has a dry color that is too light for a mollic
epipedon. The color of the upper part of the soils, after mixing to a depth of 18 cm, however, is dark enough for a
mollic epipedon because the natric horizon is nearly black. Ground water is shallow during most of the year, and
capillary rise in many Natraquolls has concentrated salts, including sodium salts, in the upper 50 cm. Natraquolls are
known to occur only in subhumid to arid regions. They are on flood plains and on the margins of lakes. They formed
in late-Pleistocene or Holocene deposits.
Paleudolls - These soils have a thick or deep argillic subsoil horizon (clay accumulation). Most of the soils have a
reddish hue and a content of clay that decreases slowly with increasing depth. Paleudolls are mainly on surfaces
older than Wisconsinan and are thought to have formed during at least one glacial stage and one interglacial stage.
These soils are mostly on the southern Great Plains and in the mountains of the Western United States. They are
extensive only locally. Slopes are gentle to steep.
Argiudolls - These soils have a relatively thin argillic subsoil horizon (clay accumulation) or one in which the
percentage of clay decreases rapidly with increasing depth. The mollic epipedon (rich in humus and bases)
commonly is black to very dark brown, and the argillic horizon is mostly brownish. Many of these soils are
noncalcareous to a considerable depth below the argillic horizon. Some Argiudolls have a zone of accumulation of
calcium carbonate below the argillic horizon. Argiudolls formed mostly in late-Wisconsinan deposits or on surfaces
of that age. Many or most of these soils supported boreal forests during the Pleistocene that were later replaced by
tall grass prairies during the Holocene. Argiudolls are extensive soils in Iowa, Illinois, and adjacent states.
Hapludolls - Generally have a cambic subsoil horizon (minimal soil development) below a mollic epipedon. There
may be a zone of calcium carbonate accumulation below the cambic horizon. Hapludolls formed mostly in Holocene
or late-Pleistocene deposits or on surfaces of that age. Slopes generally are gentle, and most of the soils are
cultivated. Hapludolls are extensive soils in Iowa, Minnesota, and adjacent states.
Natrudolls - These soils have a natric subsoil horizon (high levels of illuvial clay and sodium). Below the natric
horizon, there is normally one horizon or more in which carbonates, sulfates, or other soluble salts have
accumulated. Most Natrudolls are in small nearly level or concave areas. The soils are most common in Argentina
and on the northern Great Plains of the United States, where many of the parent materials contain salts.
Natrustolls - These soils have a natric subsoil horizon (high levels of illuvial clay and sodium). The most common
horizon sequence is either a natric horizon in the lower part of the mollic epipedon or a thin albic horizon (lightcolored leached layer) over a natric horizon with columnar structure. calcium carbonate or other salts may have
accumulated below the natric horizon. Most of the areas of these soils are small and are nearly level or concave. The
soils formed mostly in late-Pleistocene sediments.
Paleustolls - These are the Ustolls on old stable surfaces as evidenced by the development of a thick, reddish argillic
horizon, a clayey argillic horizon that has an abrupt upper boundary, or a petrocalcic horizon (calcium carbonate
cementation). They commonly have been partly or completely calcified during the Holocene, and calcium carbonate
has accumulated in the previously formed argillic horizon. The Paleustolls in the United States are mainly in the
central and southern parts of the Great Plains. At the time of settlement, they had mostly grass vegetation. Their
history during the Pleistocene has had little study. The petrocalcic horizon, where it occurs, may be complex,
suggesting a number of alternating cycles of humidity and aridity and slow accretion of dust and sediment from the
arid regions to the west.
Argiustolls - These soils have an argillic subsoil horizon (clay accumulation) in or below the mollic epipedon. Most
of these soils have an argillic horizon that, with increasing depth, has a clay decrease of 20% or more (relative) from
the maximum clay content within 150 cm of the mineral soil surface. Some of the soils have a root limiting layer
(densic, lithic, or paralithic contact) within 150 cm, and some have no hues of 7.5YR or redder or have chroma of 4
or less. Most Argiustolls have a zone of accumulation of calcium carbonate or other salts below the argillic horizon.
Argiustolls formed mostly in late-Pleistocene deposits or on surfaces of comparable age. They occur in relatively
stable positions. Slopes generally are moderate to nearly level, and most of the soils are cultivated. Argiustolls are
extensive soils on the western Great Plains and also occur in the mountains and valleys of the Western United
States.
36
Haplustolls - Most of these soils have a cambic subsoil horizon (minimal soil development) below the mollic
epipedon, and most have a horizon in which carbonates or soluble salts have accumulated. A few that formed in
noncalcareous sediments do not have a horizon of carbonate accumulation. Haplustolls formed mainly in latePleistocene or Holocene deposits or on surfaces of comparable age.
Ultisols
Suborder: Ultisols that have:
1. A seasonally high water table within 50 cm ------------------------------------------------------------- Aquults
Note: Evidence of a water table includes redoximorphic features (gray and red color patterns).
See Keys to Soil Taxonomy for criteria regarding amount, color, and location of redoximorphic features.
Begin measuring depth below any O horizon. Artificially drained sites are included in Aquults.
39TU
2. Seasonally well distributed precipitation ----------------------------------------------------------------- Udults
39TU
3. Somewhat limited soil moisture available for plant growth --------------------------------------- Ustults
Note: These soils have an ustic soil moisture regime. Moisture is limited, but available
during portions of the growing season.
39TU
U39T
U39T
U39T
Fragiaquults - These soils have a fragipan (firm and brittle, but not cemented) with an upper boundary within 100
cm. Normally, the fragipan lies below the argillic (clay accumulation) or kandic horizon (very low cation-exchange
capacity). In a few of the soils, however, it may be in the lower part of the argillic or kandic subsoil horizon.
Albaquults - These soils have a marked increase in percentage of clay at an abrupt boundary at the top of the
argillic (clay accumulation) or kandic (very low cation-exchange capacity) subsoil horizon. The subsoil horizon
generally is clayey and has moderately low or lower hydraulic conductivity. In most years water is perched for short
duration above the argillic or kandic horizon prior to complete soil saturation. Slopes are nearly level, and draining
the soils is difficult. In the Southeastern United States, these soils formed mostly in acid, late- Pleistocene sediments
and are on low marine or stream terraces. Most have a season when the upper horizons are dry. Some of the
Albaquults in the United States have been cleared for grazing or cropping, but many are forested.
Paleaquults - These soils have an argillic subsoil horizon (clay accumulation) and the percentage of clay does not
decrease from its maximum amount by as much as 20 percent within a depth of 150 cm. Paleaquults formed mostly
on mid-Pleistocene or older land surfaces, on high marine or river terraces or old deltas. They are of large extent in
the Southeastern United States. The natural vegetation consisted of forest plants, mostly water-tolerant conifers or
hardwood trees.
Epiaquults – These soils have water perched on a less permeable layer, commonly an argillic subsoil horizon.
Before cultivation, most Epiaquults supported either deciduous broadleaf or coniferous forest. Slopes generally are
nearly level.
Endoaquults - These soils have ground water that fluctuates from the soil surface to depths sometimes exceeding 2m. Before cultivation, most Endoaquults supported either deciduous broadleaf or coniferous forest plants. Generally,
the soils are nearly level.
Fragiudults - These soils have a fragipan (firm and brittle, but not cemented) within 100 cm. These soils formed
mainly in loamy alluvium or in residuum. The fragipan commonly has an upper boundary between 50 and 100 cm
below the mineral soil surface. Perched ground water is found above the pan at some period during the year, and
many of the soils have thick clay depletions (gray areas where clay and iron have been lost) near the top of the
fragipan and in vertical seams between structural units. The Fragiudults are principally found on gentle slopes
throughout the Southeastern States. The vegetation has been a forest either of mixed conifers and broadleaf
deciduous trees.
37
Paleudults – These soils are on very old stable land surfaces. These soils have a thick argillic subsoil horizon (clay
accumulation). The soils have a clay distribution in which the percentage of clay does not decrease from its
maximum amount by as much as 20% within a depth of 150 cm, or the layer in which the clay percentage decreases
has at least 5% of the volume consisting of skeletans (ped surfaces stripped of clay) and there is at least a 3%
(absolute) increase in clay content below this layer. Paleudults are extensive in the Southeastern and in Middle
Atlantic United States. Slopes generally are gently sloping or nearly level. The natural vegetation consisted of forest
plants, mostly hardwoods or mixed conifers and hardwoods. Many of these soils have been cleared and are used as
cropland or pasture.
Hapludults – These soils have an argillic subsoil horizon (clay accumulation) and a clay distribution that decreases
significantly within 150 cm. These soils have a thin or moderately thick zone of maximum clay content. Most of the
soils formed in areas of acid rocks or sediments on surfaces that are at least of Pleistocene age. Where the soils are
not cultivated, the vegetation consists of hardwood trees or conifers. Hapludults are extensive in the Southeastern
United States, in the Middle Atlantic States, and on the coastal plain along the Gulf of Mexico in the Southern States
east of the Mississippi River. Slopes generally are gently sloping to steep, but a few of the soils on the lowest part of
the coastal plain are nearly level.
Paleustults – These soils have an argillic subsoil horizon (clay accumulation). They have a clay distribution in
which the percentage of clay does not decrease from its maximum amount by as much as 20% within a depth of 150
cm from the mineral soil surface. Many of the soils have a thick argillic horizon. Commonly, there are small or
moderate amounts of plinthite (iron oxide-rich concentration) at some depth in the soils. Paleustults are on old stable
surfaces that have gentle slopes. They are very rare in the United States and are known to occur only in California.
Haplustults - These soils have a thin or moderately thick zone of maximum clay content in the argillic subsoil
horizon (clay accumulation). Slopes range from gentle to very steep. Many of these soils are in tropical climates and
are farmed by means of shifting cultivation. Haplustults are of small extent in the United States. They are mainly in
Texas, California, and Puerto Rico.
Vertisols
Suborder: Vertisols that have:
1. A seasonally high water table within 50 cm ............................................. Aquerts
(Note: evidence of a water table includes redoximorphic features. Begin measuring below any O
horizon. Artificially drained sites are included in Aquerts.)
2. Cracks in the upper 50 cm are open <90 cumulative days each year .... Uderts
(Note: seasonal cracking is for non-irrigated soils. Cracks are >5 mm wide and extend through
≥ 25 cm of the upper 50 cm.)
3. Cracks in the upper 50 cm are open ≥ 90 cumlative days each year ...... Usterts
(Note: seasonal cracking is for non-irrigated soils. Cracks are >5 mm wide and extend through
≥ 25 cm of the upper 50 cm.)
Natraquerts - These soils have natric subsoil horizon (high levels of illuvial clay and sodium). In many areas these
soils occur on flood plains or glacial lake plains. The high sodium content limits their use as cropland. Most of the
soils are used as rangeland, pasture, or hayland. Most Natraquerts in the United States formed in alluvium or
lacustrine deposits derived dominantly from sedimentary rocks. Natraquerts occur in the Dakotas, Montana, Iowa,
Nebraska, and Texas.
Epiaquerts - These soils have one or more soil layers that perch water. Commonly, these layers are close to the
surface. These soils occur on a variety of landforms, including flood plains, glacial lake plains, and depressions. In
the United States, they occur in a number of Western States, on the northern Great Plains, and in the South.
38
Endoaquerts – These soils are saturated throughout the profile. They occur in the Far Western States, on the
northern Great Plains, and in the Southern States.
Dystruderts – These are the acid Uderts. These soils are derived dominantly from acid, fine-textured materials and
occur on alluvial plains, deltas, interfluves, and side slopes. Commonly, they are underlain by sediments high in
bases. Some of these soils have diagnostic horizons, including argillic (clay accumulation), calcic (calcium
carbonate accumulation), and gypsic (gypsum accumulation) subsoil horizons. In the United States, these soils occur
in Texas and in the Southeastern States, including the Alabama and Mississippi Blackland Prairie.
Hapluderts – These soils have pH values that are dominantly above 5.0 (1:1 water) in the upper 50 cm. These soils
typically have high base saturation, and some have diagnostic horizons, including argillic (clay accumulation)
subsoil horizons. Hapluderts occur on uplands and in lower areas. They formed in a variety of fine-textured parent
material, including alluvium. In the United States, these soils occur in the Southeast but also occur on the northern
Great Plains and in the Pacific Northwest.
Haplusterts - The most common of the Usterts. They have little or no accumulation of salts and pH >5.0 (in 1:1
water). They are derived from a variety of parent materials, including sedimentary rocks, alluvium, marl, and basic
igneous rocks. Slopes range from nearly level to strongly sloping. Haplusterts occur in many Western and
Southwestern States, on the northern Great Plains, and in Puerto Rico and the Virgin Islands.
39
APPENDIX 4
Dwellings with Basements
Reason # Property
Rating Guide for Soil Interpretations
Slight
Moderate
Severe
1
Flooding (floodplain landform)
none
------
any
2
Ponding (closed depression)
no
-------
yes
3
Depth to high water table
> 180 cm
75 to 180 cm
< 75 cm
4
Depth to bedrock
> 180 cm
100 to 180 cm
< 100 cm
5
Depth to cemented pan
>150 cm
100 to 150 cm
< 100 cm
6
Slope
< 8%
8 to 15%
> 15%
7
Shrink swell
< 8 cm clay
8 to 16 cm clay
> 16 cm clay
8
% > 8 cm stones, 0 to 100 cm
< 25%
25 to 50%
> 50%
Septic Tank Absorption Field
Reason # Property
Slight
Moderate
Severe
1
Flooding (floodplain landform)
none
------
any
2
Depth to bedrock
> 180 cm
100 to 180 cm
< 100 cm
3
Depth to cemented pan
> 180 cm
100 to 180 cm
< 100 cm
4
Ponding
no
-------
yes
5
Depth to high water table
> 180 cm
120 to 180 cm
< 120 cm
6
Onsite wastewater loading rate 0.52-0.84
at 50 cm (Appendix 6)
-------
< 0.52 or > 0.84, or
NR
7
Slope
< 8%
8 to 15%
> 15%
8
% > 8 cm stones, 0 to 40 cm
< 25%
25 to 50%
> 50%
Local Roads and Streets
Reason #
Property
Slight
Moderate
Severe
1
Depth to bedrock
> 150 cm
100 to150 cm
< 100 cm
2
Depth to cemented pan
> 150 cm
100 to 150 cm
< 100 cm
3
Shrink swell
< 8 cm clay
8 to 16 cm clay
> 16 cm clay
4
Strength (avg. 25 to 100 cm)
S, LS, SL
L, SCL
all others
5
Ponding
no
------
yes
6
Depth to high water table
> 90 cm
30 to 90 cm
< 30 cm
7
Slope
< 15%
15 to 25%
> 25%
8
Flooding (floodplain landform)
none
------
any
9
Frost action
S, LS
all others
SI, SIL, SICL
10
% > 8 cm stones, 0 to 40 cm
< 25%
25 to 50%
> 50%
40
Appendix 5
Seasonal Water Table (SWT) Classes
I. Horizons with dissimilar color patterns on ped surfaces and ped interiors.
1. Brief: Soil horizons with one or more of the following.
- Concentrations or depletions on ped surfaces with chroma ≥ 3, not more than 50%
or more chroma 3 on ped surfaces.
- Manganese mases on 2% or more of the ped surface.
- Iron or manganese nodules or concretions ≥ 2 mm diameter. (Note: Iron/manganese
nodules or concretions with clear to sharp boundaries and the absence of
iron/manganese accumulations on the surface of the nodule or concretion are not
indicative of contemporary season water table levels.)
2. Moderate: Soil horizons which have one or more of the following:
- Some chroma ≤ 2 on ped surfaces.
- 50% or more chroma 3 on ped surfaces
- 35-49% clay
3. Long: Soil horizons which have one or more of the following:
- Chroma ≤ 2 on 70% or more of the ped surfaces.
- Chroma ≤ 2 on 50% or more of the ped surfaces with some chroma of 2 or less in ped
interiors.
- 50% or more clay.
II. Horizons with similar color patterns on ped surfaces and ped interiors and horizons
without peds.
1. Brief: Soil horizons with one or more of the following.
- Concentrations or depletions with chroma ≥ 3, not greater than 20% chroma 3.
- Iron or manganese nodules or concretions ≥ 2mm diameter. (Note: Iron/manganese
nodules or concretions with clear to sharp boundaries and the absence of iron/manganese
accumulations on the surface of the nodule or concretion are not indicative of
contemporary season water table levels.
2. Moderate: Soil horizons which have one or more of the following:
- Chroma ≤ 2 on less than 50% of the mass.
- Chroma 3 in more than 20% of the mass.
- 35-49% clay.
3. Long: Soil horizons which have one or more of the following:
- Chroma ≤ 2 in 50% or more of the mass.
- 50% or more clay.
41
Appendix 6
Loading Rates (gpd/ft2) For On-Site Wastewater Disposal†
Brief SWT
Moderate SWT
depth
(cm)
Long SWT
Soil Hydraulic Conductivity at 50 cm depth
Moderate HC
High HC
Moderate HC
High HC
Moderate HC
High HC
20
0
0
0
0
0
0
23
0.03
0.03
0.01
0.01
0
0
25
0.06
0.08
0.02
0.03
0.01
0.01
28
0.1
0.14
0.03
0.05
0.02
0.02
30
0.16
0.23
0.05
0.08
0.03
0.04
33
0.22
0.34
0.07
0.11
0.04
0.06
36
0.29
0.46
0.1
0.15
0.05
0.07
38
0.4
0.6
0.13
0.2
0.07
0.1
41
0.51
0.75
0.17
0.24
0.09
0.12
43
0.63
0.9
0.21
0.29
0.11
0.15
46
0.75
1.05
0.26
0.35
0.13
0.17
48
0.75
1.21
0.3
0.4
0.15
0.2
51
0.75
1.25
0.35
0.46
0.18
0.22
53
0.75
1.25
0.4
0.51
0.2
0.25
56
0.75
1.25
0.44
0.56
0.23
0.28
58
0.75
1.25
0.49
0.62
0.25
0.31
61
0.75
1.25
0.54
0.68
0.28
0.34
64
0.75
1.25
0.59
0.74
0.3
0.37
66
0.75
1.25
0.64
0.8
0.32
0.4
69
0.75
1.25
0.68
0.85
0.34
0.43
71
0.75
1.25
0.73
0.91
0.36
0.45
74
0.75
1.25
0.75
0.96
0.39
0.48
76
0.75
1.25
0.75
1.02
0.41
0.51
79
0.75
1.25
0.75
1.08
0.43
0.54
81
0.75
1.25
0.75
1.14
0.46
0.57
84
0.75
1.25
0.75
1.2
0.48
0.6
86
0.75
1.25
0.75
1.25
0.5
0.63
89
0.75
1.25
0.75
1.25
0.53
0.66
91
0.75
1.25
0.75
1.25
0.55
0.69
94
0.75
1.25
0.75
1.25
0.58
0.73
97
0.75
1.25
0.75
1.25
0.6
0.76
99
0.75
1.25
0.75
1.25
0.63
0.79
42
Appendix 6, continued.
Brief SWT
Moderate SWT
depth
(cm)
†
Long SWT
Soil Hydraulic Conductivity at 50 cm depth
Moderate HC
High HC
Moderate HC
High HC
Moderate HC
High HC
102
0.75
1.25
0.75
1.25
0.65
0.83
104
0.75
1.25
0.75
1.25
0.68
0.86
107
0.75
1.25
0.75
1.25
0.7
0.9
109
0.75
1.25
0.75
1.25
0.73
0.93
112
0.75
1.25
0.75
1.25
0.75
0.97
114
0.75
1.25
0.75
1.25
0.75
1.01
117
0.75
1.25
0.75
1.25
0.75
1.04
119
0.75
1.25
0.75
1.25
0.75
1.08
122
0.75
1.25
0.75
1.25
0.75
1.12
124
0.75
1.25
0.75
1.25
0.75
1.16
127
0.75
1.25
0.75
1.25
0.75
1.2
Assume a loading rate of 0 gpd/ft2 for soils having a low hydraulic conductivity at <51 cm.
43
I. _________
II. __________
III. __________
IV. __________
V. __________
________
________
________
________
________
Total : __________
________
Appendix 7. SCORECARD
ASA NATIONAL SOIL JUDGING CONTEST
University of Arkansas at Monticello
April 2015
I. Soil Morphology
Horizonation
Prefix
(2)
Master
(3)
Sub.
(2)
Boundary
No.
(2)
Lower
Depth
(3)
Dist
(2)
Texture
Clay%
(+)
(2)
%CF
(+ 5)
(2)
Contestant I.D. ______________________
Site No. ____________________________
Horizons____________________________
Describe to a depth of ______________cm
Nail in third horizon at ______________ cm
Score: ____
Color
Structure
Consistency
CF Mod.
Class
Hue
Value
Chroma
Grade
Shape
Moist
Strength
(2)
(4)
(2)
(2)
(2)
(2)
(2)
(2)
Redox Features
Depl.
(2)
II. Soil Profile Characteristics
Hydraulic Conductivity (10)
Surface (5)
Limiting Layer (5)
____ High
____ High
____Moderate
____ Moderate
____ Low
____ Low
Con.
(2)
Score
Possible
(40)
Score: ____
Effective Soil Depth (5)
Water Retention Difference (5)
Soil Wetness Class (5)
____ Very shallow (< 25 cm)
_____ Very low (< 7.50 cm)
____ Very shallow (< 25 cm)
____ Shallow (25-49 cm)
_____ Low (7.50-14.99 cm)
____ Shallow (25-49 cm)
____ Moderately deep (50-99 cm)
_____ Medium (15-22.49 cm)
____ Moderately deep (50-99 cm)
____ Deep (100-149 cm)
_____ High (22.5-29.99 cm)
____ Deep (100-149 cm)
____ Very deep (≥ 150 cm)
_____ Very high (≥ 30 cm)
____Very deep (≥ 150 cm)
44
III. Site Characteristics
Parent Material (5 each)
____ Alluvium
____ Colluvium
____ Loess
____ Marine
____ Residium
Score: ____
Landform (5)
____ Depression
____ Floodplain
____ Stream terrace
____ Mound
____ Inter-mound
____ Uplands
Slope Gradient (5)
Hill Slope Profile (5)
Surface Runoff (5)
Erosion Potential (5)
____ 0 to 1 %
____ Summit
____Ponded
____ Very low
____ 1 to 3 %
____ Shoulder
____Very slow
____ 3 to 5 %
____ Low
____ Backslope
____Slow
____ Medium
____ Footslope
____Medium
____ High
____ Toeslope
____Rapid
____ Very high
____ None
____Very rapid
____ 5 to 8 %
____ 8 to 12 %
____ 12 to 20 %
____ > 20 %
IV. Soil Classification
Epipedon (5)
____ Mollic
Subsurface
Horizons
(5 each)
____ Albic
Score: ____
Other Characteristics
(5 each)
____ Buried
Order (5)
____ Alfisol
Suborder (5)
____ Alb
____ Umbric
____ Argillic
____ Fe/Mn concretions
____ Entisol
____ Aqu
____ Ochric
____ Calcic
____ Fragipan
____ Inceptisol
____ Fluv
____ None
____ Cambic
____ Gypsic
____ Mollisol
____ Psamm
____ Glossic
____ Krotovina
____ Ultisol
____ Ud
____ Gypsic
____ Lithologic discontinuity
____ Vertisol
____ Natric
____ Lithic contact
____ None
____ Paralithic contact
Great Group (5)
Family Particle Size Class (5)
_____ Alb
_____ Fragi
____ Sandy-skeletal
_____ Argi
_____ Gloss
____ Loamy-skeletal
_____ Dystr
_____ Hapl
____ Clayey-skeletal
____ Coarse-silty
_____ Endo
_____ Pale
____ Sandy
____ Fine-silty
_____ Epi
_____ Psamm
____ Loamy
____ Fine
_____ Ud(i)
____ Clayey
____ Very-fine
_____ Eutr
_____ Fluv
_____ Natr
____ Plinthite
____ Slickensides
Note: For strongly contrasting classes, indicate the
upper class with a “1” and the lower class with a
“2”. Partial credit (2pts) will be given if only one of
the contrasting classes is marked. No points are
awarded if contrasting classes are numbered
incorrectly .
V. Interpretations
Dwellings with Basement (5)
_______ Slight
_______ Moderate
_______ Severe
Reason # (2):__________
____ Coarse-loamy
____ Fine-loamy
Score: ____
On-Site Wastewater Loading Rate (5)
_____ 0-0.10 gpd/ft2
_____ 0.11-0.25 gpd/ft2
_____ 0.26-0.50 gpd/ft2
_____ 0.51-0.75 gpd/ft2
_____ >0.75 gpd/ft2
Septic Tank Absorption Field (5)
_______ Slight
_______ Moderate
_______ Severe
Reason # (2): ________
Local Roads and Streets (5)
_______ Slight
_______ Moderate
_______ Severe
Reason # (2): ________
45
46