This chapter provides a brief summary of the main terminology
used to describe soils at the scales of the landscape and
pedon. It refers to the section of the Canadian Soil
Information System (CanSIS) Manual for Describing Soils in
the Field 1982 Revised (Agriculture Canada Expert
Committee on Soil Survey 1983) in which the terminology
and methods of coding descriptive data are defined in detail.
See section 8B in the Manual and Chapter 18 in this
publication.
See section 8H in the Manual and Chapter 15 in this
publication for definitions of water and wind erosion
classes.
See section 8J in the Manual and Chapter 15 herein for
definitions of stoniness classes. Terminology for coarse
fragments is given in Table 9.
See section 8K in the Manual and Chapter 15 herein for
definitions of rockiness classes.
See sections 8D, D1, D2, E, F, and G in the Manual. The
following aspects of the soil water regime are classified:
Soil Drainage, Aridity, Hydraulic Conductivity, Impeding
Layer, Depth of Saturated Zone and Duration, and Man-made
Modifiers.
See section 10C in the Manual. Munsell notations, e.g.,
10YR 5/3, (hue, value, and chroma) as well as the appropriate
color name (shown for the notation given) are used to indicate
the colors of individual horizons of the pedon. Preferably
record both moist (10YR 3/3 m) and dry (10YR 5/3 d) soil
colors and indicate whether the sample is moist (m) or dry
(d) if color is recorded at only one moisture state.
See section 10K in the Manual. Textural classes are defined
in terms of the size distribution of primary particles as
estimated by sieve and sedimentation analysis. The textural
classes are indicated in
Figure 42;
named size classes of
primary particles and their dimensions are as follows:
| very coarse sand |
2.0-1.0 |
| coarse sand |
1.0-0.5 |
| medium sand |
0.5-0.25 |
| fine sand |
0.25-0.10 |
| very fine sand |
0.10-0.05 |
| silt |
0.05-0.002 |
| clay |
≤0.002 |
| fine clay |
≤0.0002 |
| Rounded and subrounded fragments
(all kinds of rocks) |
Gravelly |
Cobbly |
Stoney (or bouldery)1 |
| Irregularly shaped angular fragments |
|
|
|
| Chert |
Cherty |
Coarse cherty |
Stony |
| Other than chert |
Angular gravelly |
Angular cobbly |
Stony |
| Thin flat fragments |
|
|
|
| Thin flat sandstone, limestone, and schist |
Channery |
Flaggy |
Stony |
| Slate |
Slaty |
Flaggy |
Stony |
| Shale |
Shaly |
Flaggy |
Stony |
1 = Bouldery is sometimes used where stones are larger
than 60 cm.
Figure 42:
Soil texture classes triangle. Percentages of clay and sand
in the main textural classes of soil; the remainder of each
class is silt. Abbreviations for the texture classes are: HC,
heavy clay; C, clay; SiC, silty clay; SiCL, silty clay loam;
CL, clay loam; SC, sandy clay; SiL, Silt Loam; L, loam; SCL,
sandy clay loam; SL, sandy loam; Si, silt; LS, loamy sand; S,
sand.;
See section 10L in the Manual. Mottles are spots or blotches
of different color, or shade of color, interspersed with the
dominant soil color. Note the color of the matrix and the
principal mottles, and the pattern of mottling. The latter
is indicated in terms of abundance (few, common, many), size
(fine, medium, coarse), and contrast with the matrix (faint,
distinct, prominent).
See section 10M in the Manual. Soil structure refers to the
aggregation of primary soil particles into compound particles
that are separated from adjoining aggregates by surfaces of
weakness. Soil structure is classified in terms of grade or
distinctness (weak, moderate, strong), class or size (fine,
medium, coarse, very coarse), and type (granular, platy,
prismatic, blocky). See Table 10 and
Figure 43.
See section 10N in the Manual. Soil consistence refers to the
soils resistance to deformation or rupture and its degree of
cohesion and adhesion. Consistence of wet soil is classified
in terms of stickiness (nonsticky, slightly sticky, sticky,
or very sticky) and plasticity (nonplastic, slightly plastic,
plastic, or very plastic). Consistence is classified for moist
soil as loose, very friable, friable, firm, or very firm. For
dry soil consistence is classified as loose, soft, slightly
hard, hard, very hard, extremely hard, or rigid. Cementation
refers to brittle, hard consistence due to some cementing
substance. The classes of cementation are weakly cemented,
strongly cemented, and indurated.
See section 10T in the Manual. Abundance, size, orientation,
distribution, and depth of root penetration are noted.
See section 10U in the Manual. Abundance, size, orientation,
distribution, continuity, morphology, and type of pore are
estimated and noted.
See section 10S in the Manual. Clay films are described in
terms of frequency, thickness, location, and color.
See section 10P in the Manual. The lower boundary of each
horizon is described in terms of distinctness (abrupt, clear,
gradual, or diffuse) and form (smooth, wavy, irregular, or
broken).
See Pihlainen and Johnston (1963), Brown and Kupsch (1974),
and Harris et al. (1988) for terminology that describes ice
and other features of permafrost soils.
See sections 8 and 10 in the Manual. Some other features of
soils and sites that may be described are humus form,
permafrost, land use, concretions, nodules, calcareousness,
salinity, coarse fragments, and reaction.
Descriptive data for soils are commonly entered on CanSIS
forms, but conventional descriptions are needed for some
purposes. The following order of listing properties is
recommended: color, texture, mottles, structure, consistence,
roots, pores, clay films, concretions, carbonates, salts,
coarse fragments, horizon boundary, thickness range, and
reaction. A description of a Gleyed Humo-Ferric Podzol
follows:
| L-H |
7.5-0 |
Black (10YR 2/1 m), dark grayish brown
(10YR 4/1 d); semi-decomposed organic matter; fibrous,
abundant, fine and medium roots; abrupt, smooth
boundary; 5-10 cm thick; acid. |
| Ae |
0-10 |
Gray (5YR 6/1 m), light gray (5YR 7/1 d);
sandy loam; single grain; loose, friable; few, fine
and medium roots; few, fine, vesicular pores; clear,
wavy boundary with some fine tongues into underlying
horizon; 5-12 cm thick; acid. |
| Bfgj |
10-30 |
Reddish brown (5YR 4/4 m, 5/4 d); sandy
loam; common, medium, distinct strong brown (7.5 YR
5/6) mottles; amorphous; friable; few, fine and very
fine roots; few, medium and fine pores; some gravel;
clear, smooth boundary; 15-25 cm thick; acid. |
| Bfg |
30-61 |
Reddish brown (5YR 4/3 m, 5/3 d); sandy
loam; many, medium to coarse, prominent strong brown
(7.5 YR 5/6) mottles; amorphous; firm; few stones;
clear, smooth boundary; 20-38 cm thick; acid. |
| C |
61+ |
Reddish brown (2.5YR 4/4 m, 5/4 d) sandy
loam; amorphous; firm; slightly plastic; some stones;
acid. |
| Structureless:
no observable aggregation or no definite
orderly arrangement around natural lines of weakness |
Single grain
structure:
loose, incoherent mass of individual
particles as in sands |
|
|
| |
Amorphous
(massive) structure:
a coherent mass showing no evidence of any distinct
arrangement of soil particles |
|
|
| Blocklike:
soil paticles are arranged around a point and
bounded by flat or rounded surfaces |
Blocky
(angular blocky):
faces rectangular and flattened, vertices sharply
angular |
Fine blocky
Medium blocky
Coarse blocky
Very coarse blocky |
<10
10-20
20-50
>50 |
| |
Subangular blocky:
faces subrectangular, vertices mostly
oblique, or subrounded |
Fine subangular blocky
Medium subangular blocky
Coarse subangular blocky
Very coarse subangular blocky |
<10
10-20
20-50
>50 |
| |
Granular:
spheroidal and characterized by rounded vertices |
Fine granular
Medium granular
Coarse granular |
<2
2-5
5-10 |
| Platelike:
soil particles are arranged around a horizontal
plane and generally bounded by relatively flat
horizontal surfaces |
Platy structure:
horizontal planes more or less developed |
Fine platy
Medium platy
Coarse platy |
<2
2-5
>5 |
| Prismlike:
soil particles are arranged around a vertical axis
and bounded by relatively flat vertical surfaces |
Prismatic structure:
vertical faces well defined, and edges sharp |
Fine prismatic
Medium prismatic
Coarse prismatic
Very coarse prismatic |
<20
20-50
50-100
>100 |
| |
Columnar structure:
vertical edges near top of columns not sharp; columns
flat-topped, round-topped or irregular |
Fine columnar
Medium columnar
Coarse columnar
Very coarse columnar |
<20
20-50
50-100
>100 |
Figure 43:
Types, kinds, and classes of soil structure.
|