Soil profile descriptions

PU RPOSE The pu rpose of th is exercise is to take the student into the field to dig in soils, to appreciate the characteristics of soil differences outlined in pages 1-40 of the textbook. This exer­cise can consist of several short field trips, or several half-days of describing different soils according to the format given on pages 8 and 10 of the textbook.

PROCEDURE Dig several pits in the middle of several different, well-defined landscape segments, as illustrated in Figure 1. The pits should exhibit highly contrasting soil properties. Each student should describe the environment and horizon characteristics in each pit according to Tables 1 and 2. Preparation includes discussion of pages 1-40 of the textbook and instruction on soils of the local area. Classroom exhibits of sand, clay, mottles, blocky and platy structures, and so on, can provide useful preparation for fieldwork. Instructions in determination of textures, con­sistence, and pH can be conveniently done in the classroom before students go into the field to make a soil profile description. Pages 24-26 of the text­book describe a practical exercise for determining soil texture that has proved to be quite useful in preparing to teach about soil profile descriptions.

COMPETITION A competitive element can be introduced into the student activity by using the forms illustrated in Tables 3 and 4. Under the sponsorship of the American Society of Agrono­my, soils contests are held each fall (regionally) and each spring (nationally) in the United States. Host states are rotated among colleges offering B.s. training in soils. Thus, by participating in soils

contests for four years, undergraduates have the opportunity to see many different soils and to meet the people working in the profession. Of course, unofficial contests can be held among participants of any class or group. The scorecards in Tables 3 and 4 offer a convenient means to grade individual performance in description of a soil. Each score­card is changed somewhat from year to year and modified to fit local soil situations. Typically, numerous pages of explanatory materials accom­pany the scorecards for the students and coaches to study. The scorecards also require some classifi­cations and interpretive judgments to be made about the soils, so that the value of the descriptive data are readily apparent to the students.

CHANGES Soil survey is one area of study where change is a continual process and a mark of progress. In 1981, for example, soil profile hori­zon designations given on page 14 of the textbook were modified somewhat to fit the international nomenclature more closely. Guthrie and Witty (1982) provided a synoptic comparison between the old (1962) and new {1981} designations for soil horizons and layers, also given in Table 5. Of course, most current published soil survey reports contain the nomenclature given on page 14 of the textbook, and the new terminology will not appear in many soil survey reports until after a number of years have passed.

REFERENCE

Guthrie, R. L. and J. E. Witty. 1982. New designations for soil horizons and layers and the new Soil Survey Man­ual. Soil Science Society of America Journal 46:443-444.

FIGURE ljSchematic diagram of a soil pit in a soil map landscape unit, from which the soil profile description area has been expanded to give a better view.

3

G. W. Olson, Field Guide to Soils and the Environment Applications of Soil Surveys© Dowden & Culver, Inc. 1984

TABLE 1/ Form for describing environment around the site (cut, pit, or trench) for a soil profile description.

Soil type File No.

Area Date Stop No.

Classification

Location

N. veg. (or crop) I Climate

Parent material

Physiography

Relief Drainage Salt or alkali

Elevation Gr. water Stoniness

Slope Moistur('

Aspect Root distrib.

Erosion

Permeability

Additional notes

TABLE 2/Form for describing horizons of a soil profile.

Color Consistence Hori- Depth Texture Struc- Re- Bound zon ture action ary

Dry Moist Dry Moist Wet

4 / Field Guide to Soils and the Environment

\.Il

TA

BLE

3jS

core

card

for

the

798

0 re

gion

al s

oils

con

test

in N

ew Y

ork

Stat

e.

Co

nte

st N

umbe

r

Pit

Num

ber _

__

__

_

Par

t I

-S

ite C

hara

cte

rist

ics

POSI

TIO

N

OF

SIT

E

(5)

__

Flo

od

pla

in

Str

eam

terr

ace

__

Upl

and

__

Fo

ots

lop

e

__

Dep

ress

ion

PARE

NT

MA

TERI

AL

(5)

Res

iduu

m

All

uviu

m

Col

luvi

um

Gla

cial

Til

l

Loe

ss

Mar

ine

and

/or

lacu

stri

ne

Gla

cial

out

was

h

SLO

PE

(5)

__

Nea

rly

lev

el

0-3%

__

Gen

tly

slo

pin

g 3

-8%

Mod

erat

ely

slo

pin

g 8

-15%

Str

on

gly

slo

pin

g 1

5-25

%

Mod

erat

ely

stee

p 2

5-35

%

__

Ste

ep 3

5+

%

ERO

SIO

N

(5)

__

__

Dep

osi

tio

n

Non

e to

sli

gh

t

Mod

erat

e

Sev

ere

1980

NOR

THEA

ST

REG

ION

AL

COLL

EGIA

TE

SOIL

S CO

NTE

ST

SCOR

ECAR

D O

ctob

er I

I, 1

980

Sco

re I

II ----

Co

rnel

l U

niv

ersi

ty

Par

t I

-co

nti

nu

ed

SURF

ACE

RUN

OFF

(5)

Pond

ed

__

Ver

y sl

ow

Slow

Med

ium

__

Rap

id

__

Ver

y ra

pid

Par

t II

-S

oil

Cla

ssif

icati

on

EPIP

EDO

N

(5)

Ant

hrop

ic

His

tic

Mo

llic

Och

ric

__

Pla

ggen

Um

bric

SUBS

URF

ACE

HO

RIZO

N

(5)

__

Agr

ic

Alb

ic

Arg

illi

c

Cal

cic

Cam

bic

__

Dur

ipan

Fra

gip

an

__

Gyp

sic

ORDE

R (5

)

Alf

iso

l

Ari

dis

ol

En

tiso

l

His

toso

l

__

In

cep

tiso

l

Nat

ric

Oxi

c

Pet

roca

lcic

__

_ P

etro

gy

psi

c

Pla

cic

Sal

ic

Som

bric

__

Spo

dic

Su

lfu

ric

Mo

llis

ol

Ox

iso

l

__

Spo

doso

l

Ult

iso

l

Ver

tiso

l

III

IV

& V

----

TOTA

L _

__

_

Par

t II

I -

So

il I

nte

rpre

tati

on

Lim

itat

ion

s

SEPT

IC T

ANK

ABS

ORP

TIO

N

FIEL

D

(5)

Sli

gh

t

Mod

erat

e

Sev

ere

DWEL

LING

WIT

H BA

SEM

ENT

(5)

Sli

gh

t

Mod

erat

e

Sev

ere

LOCA

L RO

ADS

AND

STRE

ETS

(5)

Sli

gh

t

Mod

erat

e

Sev

ere

LAND

C

APA

BIL

ITY

CL

ASS

AN

D

SUBC

LASS

(1

0)

0'1

TA

BL

E 3

(co

ntin

ued)

Part

IV

-

Pro

file

desc

rip

tio

n

Num

ber

of

ho

rizo

ns

to b

e d

escr

ibed

D

epth

of

ho

rizo

ns _

__

__

__

_ _

Low

er

Dis

tin

ctn

ess

bo

unda

ry

of

low

er

Hor

izon

d

epth

,cm

. bo

unda

ry

(4)

(2)

(2)

Part

V -

Pro

file

ch

ara

cte

rist

ics

INFI

LTR

ATI

ON

RA

TE

(5)

Slow

Mod

erat

e

Rap

id

PER

MEA

BIL

ITY

(5

)

Slow

Mod

erat

e

Rap

id

EFFE

CTI

VE

SOIL

D

EPTH

(5

)

Dee

p (>

100

cm)

Mo

der

atel

y d

eep

(50-

100

cm)

Sha

llow

(2

5-50

cm

)

Ver

y sh

allo

w

«2

5 c

m)

Mo

ttli

ng

A

bund

ance

1 Cont

ract

T

extu

re

Co

lor

of

mo

ttli

ng

o

f m

ott

lin

g

(4)

(2)

__

(I)

_

_ (1

)

SOIL

D

RAIN

AG

E CL

ASS

(5

)

__

Som

ewha

t ex

cess

ivel

y d

rain

ed

Wel

l d

rain

ed

Mo

der

atel

y w

ell

dra

ined

____

_ So

mew

hat

po

orl

y d

rain

ed

____

_ P

oo

rly

dra

ined

____

_ V

ery

po

orl

y d

rain

ed

AV

AIL

ABL

E W

ATE

R-H

OLD

ING

CA

PACI

TY

(5)

__

Hig

h

St .

... ,.

......

.. M

oist

T

ype I G

rade

co

nsi

sten

ce

Sco

re

(2)

(2)

(2)

-

Sco

re I

V _

____

_ __

V _

__

_

Su

bto

tal

IV

+

V _

____

_ __

TIEB

REA

KER

Hor

izon

M

ediu

m

Low

_

_ %

San

d _

_ %

Sil

t _

_ %

Cla

y

Ver

y lo

w

TABLE 4j5corecard for the 1982 national soil contest in Arkansas.

NATIONAL SOILS CONTEST: FAYETTEVILLE, ARKANSAS, APRIL 1982

CONTES TANT 1. 0 •

SITE 1.0.

PART I - SITE CHARACTERISTICS

POSITION OF SITE (5)

Flood Plain ---___ Stream Terrace ___ Upland

PARENT MATERIAL (5)

___ ,Alluvium ___ Residuum

SLOPE (5 )

0-1 "I. 1-3% 3-8% 8-12% 12-20% .---20% +

EROSION (5)

Class 1 Class 2 Class 3 Class 4

SOIL LOSS (5) t/ha·y

Ba re _______ _

Fescue ____ _

Family Particle Size Class (5)

FAMILY NAME:

PART III - SOIL CLASSIFICATION

EPIPEDONS (5)

___ Mollic ___ Ochric ___ 'Umbric ___ No Epipedon

SUBSURFACE (5)

___ Argillic ___ Cambic ___ None ___ Fragipan ____ Lithic Contact ____ Paralithic

Contact

ORDER (5)

____ ,A1£isol ____ Entisol _____ Inceptisol ___ -.:Moll isol ___ Ultisol

GREATGROUP (5)

____ Fragiaqualf ____ Glossaqualf ___ A 1 baqua 1£ ___ Ochraqualf ____ Fragiudalf ___ Paleuda1£ ___ Hapluda1£ ___ Fluvaquent ___ Udifluvent ____ Haplaquept ____ E·ltrochrept _ __ Dystrochrept _____ Argiaquoll

____ Haplaquoll ____ Paleudo11 ____ .Argiudoll ___ Hap 1 udo 11 ____ Fragiaquult ____ Albaquult ____ Paleaquult ____ Ochraquult ___ Fragiudult ______ Paleudult _ __ Rhodudult ____ Hapludult

(5 points for a correctly constructed name or 10 points for a name cor­rect at all levels except the subgroup.)

Soil Profile Descriptions j 7

00

TA

BL

E 4

(co

ntin

ued)

PA

RT

II

-SO

IL

MO

RPH

OLO

GY

Ho

rizo

n

Dep

th

Bo

un

dar

y

San

d C

lay

T

extu

re

em

Dis

t.

%

%

(2)

(2)

(2)

(1)

(1)

(3)

--

__

__

__

__

__

_

I _

__

--

PART

IV

-

INTE

RPR

ETA

TIO

NS

HY

DRA

ULI

C C

ON

D./S

UR

FAC

E (5

)

__

_ H

igh

Mo

der

ate

---

Low

---

HY

DRA

ULI

C C

ON

D./S

OIL

(5

)

__

_ H

igh

__

_ M

od

erat

e _

__

Low

WAT

ER

RET

ENTI

ON

D

IF.

(5)

Hig

h >

22

.5

em

Med

ium

1

5-2

2.5

em

Lo

w

7.5

-15

em

V

ery

Low

<

7.5

em

WET

NES

S C

LASS

(5

)

Cla

ss

1:

>15

0 em

C

lass

2

: 1

00

-15

0 e

m

Cla

ss

3:

50

-10

0

em

----

Cla

ss

4:

25

-50

em

C

lass

5

: <2

5 em

Co

lor

(2)

Mo

ttli

ng

S

tru

ctu

re

Gra

de

Sha

pe

(2)

(2)

(2)

USE

FULN

ESS

TO

AG

RIC

ULT

UR

E (8

)

__

__

_ P

rim

e F

arm

lan

d

__

__

Ad

dit

ion

al

Far

mla

nd

----

of

Sta

tew

ide

Imp

ort

ance

N

eit

her

of

the

Abo

ve

ON

SITE

W

AST

EWA

TER

REN

OV

ATI

ON

(8

)

__

__

Sta

nd

ard

F

ilte

r F

ield

I I I

__

__

,Mod

ifie

d S

tan

dard

/Pre

s.

Dis

t.

__

_ N

eit

her

of

the

Abo

ve

TABLE 5/01d and new designations for soil horizons and layers (adapted from Guthrie and Witty, 7982).

Master Horizons and Layers

Old New

0 0 01 Oi,Oe 02 Oa,Oe A A

A1 A A2 E A3 AB or EB AB

A&B E/B AC AC

B B B1 BA or BE

B&A B/E B2 B or Bw B3 BC or CB C C R R

Subordinate Distinctions within Master Horizons

Old New

b cn

f g h

ca m sa

P si

ir t

x cs sa

a b c e f g h

k m n o p q

s t v

Highly decomposed organic matter Buried soil horizon Concretions or nodules Intermediately decomposed organic matter Frozen soil Strong gleying Iliuvial accumulation of organic matter Slightly decomposed organic matter Accumulation of carbonates Strong cementation Accumulation of sodium Residual accumulation of sesquioxides Plowing or other disturbance Accumulation of silica Weathered or soft bedrock Illuvial accumulation of sesquioxides Accumulation of clay Plinthite

w Color or structural B x y z

Fragipan character Accumulation of gypsum Accumulation of salts

Soil Profile Descriptions / 9