Activities for Today Texture Determine texutral classes by feel Identify textures of unknown samples Soil Color Understand terminology of the Munsell color system hue value ID: 811996
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Slide1
Lab 2:
Soil Properties and Profiles
Slide2Activities for Today
Texture:
Determine
texutral
classes
by feel
Identify textures of unknown samples
Soil Color
:
Understand terminology of the
Munsell
color system
(hue, value,
chroma
)
Use it to determine soil color
Nomenclature
Learn the
nomenclature
for master horizon suffixes and transition horizons
Use them in labeling horizons on a monolith or soil profile description
Slide3Soil Texture
Textural classes
of soils are named on their predominant feel and correspond to percentages of
sand
,
silt
, and
clay
.
Slide4Soil Texture
Sandy textures
– gritty, rough
Silty textures
- smooth, soft, and floury
Clay textures
- stiff, waxy, and plastic
Slide5How to Texture
Golf-ball-sized amount of soil in your hand
Soil needs to be moist but not wet (add water slowly)
Knead the soil between your thumb and fingers
Ribbon (?)/ Gritty, waxy, smooth
Slide6Makes NO ribbon
<1” (weak) ribbon; not stiff, waxy
1-2” (moderate) ribbon
> 2” ribbon; v. stiff, waxy
Very gritty
SAND/
LOAMY SAND
SANDY LOAM
SANDY CLAY LOAM
CLAY
Intermediate gritty vs. smooth
-------LOAMCLAY LOAMCLAYVery smooth; little grit--------SILT LOAMSILTY CLAY LOAMCLAY
How To Texture
Slide7Slide810YR 6/8
Munsell
Soil Color Chart
Hue
Value
Chroma
Slide9Soil Color Determination
Hue
– dominant spectral color of the entire page of chips. 10YR- all chips on the page are composed of 10 parts of yellow(Y) to 1 part red(R).
Value
– lightness or darkness of the color. 8- light color and 2 – dark color (high humus content)
Chroma
– brightness or dullness of a color chip. 1- dull (grayish/waterlogged) and 8 bright (oxidation)
Slide10Soil Color
Dark brown/black
- ( A horizon) top soils, humus- decomposed organic material. A few percent of humus gives a brownish color and up to 5% the soil becomes black.
Slide11Topsoil Humus
Slide12Soil Color
Reds and Yellows- (B horizons) iron oxide formed during weathering,
Fe
+3
is well oxidized (well-drained)
Slide13Soil Color—Fe
3+
Red=Hematite Fe
2
O
3
Yellow=Goethite
FeO(OH)
Slide14Georgia Red Clay
Kaolinite Hematite and Goethite
Slide15Soil Color
Grey colors are caused by reduced Iron (Fe
+2
)
Water has excluded oxygen from diffusion into soil
Other pigments are leached out from horizons (humus, iron oxides)
Slide16Slide17Matrix color – main or background color
Mottles – other colors within the matrix
Redoximorphic
features – reduction of Fe and oxidation of Fe.
Soil Color: Mottles and Redox
Slide18Slide19Redox Features
Fe
3+
Concentrations and Depletions
Slide20Soil Structure
Slide21Special Clues to ID HorizonsBlocky=B HorizonClay Films=
Bt
horizon
Clay increase=B Horizon
Blocky but no clay increase=
Bw
Massive=C HorizonMatrix Chroma <2 add g suffix
Slide22Horizon Designations
O Horizon: organic debris
a – Highly decomposed litter
e – intermediate , partially decomposed litter
i
– slightly decomposed, identifiable litter
Slide23Oi—Identifiable Organic Material
Slide24Oe
—Partially Decomposed Organic Material
Slide25Horizon Designations
A Horizon: contains humus
p – plowed, shown by sharp lower boundary
b – buried, A-type horizon found buried in profile
E horizon: light-colored, leached; NO suffixes
Slide26Dothan Soil
A
E
B
REDOX
Slide27Horizon Designations
B Horizon: material moved INTO
h-
illuvial
humus present
t- clay
inc.
compared to A; clay films w- NO clay increase; blocky structure g- gleyed
(
chroma
≤ 2)
C Horizon: weathered parent material r- hard to dig; almost R g – gleyed (chroma ≤ 2)“types” of B horizons: only 1 in each profile
Slide28Horizon Designations
Suffixes that are numbers are used to indicate different parts of the same horizon.
Bt-Bt1, Bt2
Transition horizon- occurs between two master horizons that have the properties of both.
“AE” transition layer is between A and E horizons, more like an A than an E.
Slide29O: leaf litter at top
either “a”, “e”, or “
i
”
A: topsoil (humus)
add “p” if abrupt
E: same texture as A; often light color
Transition horizons: either EB or BE
B horizon either “t”, “w”, or “h”; add “”g
”
Transition (maybe)
C horizon: add “g” or “r” if necessaryR: can’t dig it….
Slide30Piedmont Upland
Residual Soil developed from rock weathering in place; entire sequence can be very deep—50m or more
Slide31Special Clues to ID HorizonsBlocky=B HorizonClay Films=
Bt
horizon
Clay increase=B Horizon
Blocky but no clay increase=
Bw
Massive=C HorizonMatrix Chroma <2 add g suffix
Slide32_ 0-1” hardwood leaves and twigs_ _1”-6” 10YR 3/4 sandy loam granular
_ _
6”-13” 10YR 6/3 sandy loam granular
_
13”-25” 2.5YR 4/6 clay blocky
_
25”-35” 5YR 5/6 clay loam blocky_ _35”-47” saprolite massive_ _47+” hard gneiss and schistPractice Soil Profile #1
Slide33Practice Soil Profile #1
Oi
_ 0-1” hardwood leaves and twigs
_A_
1”-6” 10YR 3/4 sandy loam granular
_E_
6”-13” 10YR 6/3 sandy loam granular
_
Bt
13”-25” 2.5YR 4/6 clay blocky
_BC 25”-35” 5YR 5/6 clay loam blocky_C_35”-47” saprolite massive_R_47+” hard gneiss and schist
Slide34___
--0 to 8 inches; reddish brown (5YR 4/4) loam; moderate medium granular structure; friable; many fine roots; common fine pores; common fine black concretions; slightly acid, abrupt smooth boundary. (2 to 11 inches thick)
___
--8 to 17 inches; yellowish red (5YR 4/6) clay; moderate medium
subangular
blocky structure; firm, sticky, plastic; common fine roots; few fine pores; many fine black concretions; common distinct clay films on faces of
peds
; slightly acid; gradual wavy boundary.
___
--17 to 25 inches; yellowish red (5YR 5/6) clay; common fine distinct brownish yellow (10YR 6/6) mottles; moderate medium
subangular
blocky structure; firm, sticky, plastic; few fine roots; few fine pores; common black concretions; common distinct clay films on faces of peds; slightly acid; gradual wavy boundary. (Combined thickness of the Bt horizon is 12 to 35 inches.) ___--25 to 36 inches; yellowish red (5YR 5/6) clay loam; common medium faint reddish yellow (7.5YR 6/6) and common fine distinct yellowish brown (10YR 5/4) mottles; weak subangular blocky structure; firm, sticky, plastic; few fine black concretions; common fine lenses of gray clayey saprolite; slightly acid; gradual wavy boundary. (3 to 15 inches thick) ___--36 to 60 inches; mottled yellowish red (5YR 5/6), reddish yellow (7.5YR 6/6) and yellowish brown (10YR 5/4) highly weathered saprolite that has a sandy clay loam texture; massive; friable; many black and gray minerals; slightly acid
Slide35___
--0 to 8 inches; reddish brown (5YR 4/4)
loam
; moderate medium
granular
structure; friable; many fine roots; common fine pores; common fine black concretions; slightly acid, abrupt smooth boundary. (2 to 11 inches thick)
___
--8 to 17 inches; yellowish red (5YR 4/6)
clay
; moderate medium
subangular
blocky structure; firm, sticky, plastic; common fine roots; few fine pores; many fine black concretions; common distinct clay films on faces of peds; slightly acid; gradual wavy boundary. ___--17 to 25 inches; yellowish red (5YR 5/6) clay; common fine distinct brownish yellow (10YR 6/6) mottles; moderate medium subangular blocky structure; firm, sticky, plastic; few fine roots; few fine pores; common black concretions; common distinct clay films on faces of peds; slightly acid; gradual wavy boundary. (Combined thickness of the Bt horizon is 12 to 35 inches.) ___--25 to 36 inches; yellowish red (5YR 5/6) clay loam; common medium faint reddish yellow (7.5YR 6/6) and common fine distinct yellowish brown (10YR 5/4) mottles; weak subangular blocky structure; firm, sticky, plastic; few fine black concretions; common fine lenses of gray clayey saprolite; slightly acid; gradual wavy boundary. (3 to 15 inches thick) ___--36 to 60 inches; mottled yellowish red (5YR 5/6), reddish yellow (7.5YR 6/6) and yellowish brown (10YR 5/4) highly weathered saprolite that has a sandy clay loam texture; massive; friable; many black and gray minerals; slightly acid
Slide36Ap
--0 to 8 inches; reddish brown (5YR 4/4) loam; moderate medium granular structure; friable; many fine roots; common fine pores; common fine black concretions; slightly acid, abrupt smooth boundary. (2 to 11 inches thick)
Bt1
--8 to 17 inches; yellowish red (5YR 4/6) clay; moderate medium
subangular
blocky structure; firm, sticky, plastic; common fine roots; few fine pores; many fine black concretions; common distinct clay films on faces of
peds
; slightly acid; gradual wavy boundary.
Bt2
--17 to 25 inches; yellowish red (5YR 5/6) clay; common fine distinct brownish yellow (10YR 6/6) mottles; moderate medium
subangular
blocky structure; firm, sticky, plastic; few fine roots; few fine pores; common black concretions; common distinct clay films on faces of peds; slightly acid; gradual wavy boundary. (Combined thickness of the Bt horizon is 12 to 35 inches.) BC--25 to 36 inches; yellowish red (5YR 5/6) clay loam; common medium faint reddish yellow (7.5YR 6/6) and common fine distinct yellowish brown (10YR 5/4) mottles; weak subangular blocky structure; firm, sticky, plastic; few fine black concretions; common fine lenses of gray clayey saprolite; slightly acid; gradual wavy boundary. (3 to 15 inches thick) C--36 to 60 inches; mottled yellowish red (5YR 5/6), reddish yellow (7.5YR 6/6) and yellowish brown (10YR 5/4) highly weathered saprolite that has a sandy clay loam texture; massive; friable; many black and gray minerals; slightly acid
Slide37