alkaline soil, alkalinity—Alkaline soils have
laboratory measured pH values >8.5. Alkalinity may inhibit
the growth of plants.
allelopathy—Effect of chemical products of one plant
(usually reducing growth, survival or reproduction) on another.
Alluvial Soils—GSG classification—Soils developed
from recently deposited alluvium, normally characterise little
or no modification of the deposited material by soil forming
processes, particularly with respect to soil horizon
development.
alluvial terrace—Former floodplain which either no
longer floods or rarely floods due to deepening or enlargement
of the stream channel.
alluvium—A deposit of sand, mud, etc. formed by flowing
water.
Alpine Humus Soils—GSG classification—Characterised
by a marked accumulation of well-humified organic matter that is
intimately incorporated in the mineral soil to form thick
surface horizons of profiles otherwise showing little horizon
development.
andesite—Fine-grained volcanic rock composed of
andesine (plagioclase) with one or more mafic constituents.
Anthroposols—ASC Soil Order classification—Soils
resulting from human activities.
apedal—In the moderately moist to moist state, none of
the soil material occurs in the form of peds; it is massive or
single-grained and when disturbed, separates into fragments or
primary particles.
aquiclude—A material which will not transmit water.
argic horizon—A subsoil horizon consisting of distinct
lamellae.
ASC—Australian Soil Classification—It is a
multi-category scheme with classes defined on the basis of
diagnostic horizons or materials and their arrangement in
vertical sequence as seen in an exposed soil profile.
available soil water—That part of the water in the soil
that can be absorbed by plant roots, that can be held between
field capacity and the moisture content at which plant growth
ceases.
available waterholding capacity—The ability to hold
that part of the water in the soil that can be absorbed by plant
roots. Available water is the difference between field capacity
and permanent wilting point.
B
B horizon—The layer of soil below the A horizons,
usually of finer texture (ie, more clayey), denser and stronger
in colour. Thickness ranges from 10 cm to 2 m thick and is
divided into B1 and B2 horizons.
backplain—Large flat at some distance from the stream
channel which often has a high watertable and receives fine
sediment from overbank deposition; in some cases biological
(peat) accumulation occurs.
batter—The excavated or constructed face of a dam wall,
cutting or embankment.
bauxitic horizon—One which contains more than 20%
(visual abundance estimate) of bauxite nodules or concretions
which are mostly uncemented. It has a minimum thickness of 0.1
m.
bench—A strip of relatively level earth or rock
breaking the continuity of a slope. Usually separated by a rock
scarp. Inside refers to the upper slope component. Outside
refers to the lower slope component above the scarp.
bioturbation—A movement of soil material within the
soil profile by animals or plants.
Black Earths—GSG classification—Black, heavy clay,
alkaline to neutral soil with wide, deep cracks when dry.
blow-out—A closed depression formed in the land surface
by wind erosion removing material and depositing it on adjacent
land.
bolus—A small handful of soil which has been moistened
and kneaded into a soil ball which just fails to stick to the
fingers.
borrow area—An area or excavation from which soil,
clay, sand, rock or gravel has been excavated for a specific
purpose.
boundaries—The boundary between soil horizons defines
the nature of the change from one horizon to that below. It is
specified by two terms—one a measure of the width of the
transition zone between the two horizons, the other a
description of its shape.
Brown Clays—GSG classification—see Grey, Brown and
Red Clays.
Brown Earths—GSG classification—Uniform yellowish,
reddish or brown, moderately acid to neutral light loams to clay
with a crumb or fine sub-angular blocky structure, showing
little profile differentiation.
Brown Hardpan Soils—GSG classification—see Red and
Brown Hardpan Soils.
Brown Podzolic Soils—GSG classification—Acid,
predominantly brownish to yellowish soils, lacking or with a
weak A2 horizon and generally have weakly to
moderately differentiated profiles with merging horizons.
C
C horizon—Layers below the B horizon which may be
weathered, consolidated or unconsolidated parent material little
affected by biological soil-forming processes.
Cainozoic—Geological period 65 million years ago to
present.
Calcareous Red Earths—GSG classification—Red,
massive, sandy to loamy soils, porous and "earthy" in
fabric, with some free carbonates in the lower part of the
profile.
Calcareous Sands—GSG classification—Sands that show
no profile development beyond some accumulation of organic
matter in the surface horizon when they have been fixed by
vegetation for sufficient time.
Calcarosols—ASC Soil Order classification—Soils that
are either calcareous throughout the solum or at least directly
below the A1 horizon.
calcrete—Any cemented terrestrial carbonate
accumulation that may vary significantly in morphology and
degree of cementation. Encompasses a wide range of calcareous
material.
calcrete pan—A moderately, strongly or very strongly
cemented layer of calcrete which is either continuous, or if
discontinuous or broken, consists of at least 90% of hard
calcrete fragments.
carbic materials—Organic debris accumulated by
colluvial and alluvial processes when torrential rain occurs
following bushfires, i.e. charcoal.
Chernozems—GSG classification—Similar to Black
Earths, but of lower clay content and more friable, having
porous structural units. The profile shows weak horizon
differentiation with gradual boundaries. Soil reaction is
neutral to alkaline.
Chocolate Soils—GSG classification—Brownish, acid,
friable, moderately pedal to fine blocky structured, clay loam
soils with weak to moderate horizon differentiation.
Chromosols—ASC Soil Order classification—Soils with a
clear or abrupt textural B horizon where the major half of the B2horizon
is not strongly acid.
clear boundary—Boundary 20 – 50 mm wide.
closed-sedgeland—Vegetation structure dominated by
sedges with a canopy cover of 70 - 100% of the ground area.
coffee rock—A type of brownish sand rock or soil pan
formed where iron oxides and organic matter, which have leached
through the soil profile, are precipitated at or above a
fluctuating watertable.
coherent—Means that two-thirds or more of the soil
material, whether composed of peds or not, will remain united at
the given moisture stage unless force is applied.
colluvium—Unconsolidated soil and rock material moved
largely by gravity (ie, mass movement), deposited on a lower
slope and/or at the base of a slope.
competent—Ability of flowing water to transport large
particles.
concavo-convex—Concave (waning) lower slope; convex
(waxing) upper slope.
consistence—Comprises the attributes of the soil
material that are expressed by the degree and kind of cohesion
and adhesion or by the resistance to deformation or rupture.
cowal—A swamp, small lake, small swampy depression or
an old stream bed often associated with stagnant and alluvial
plains.
creep—More or less imperceptible but continuous
movement of soil down a slope.
crevasse splay—Sediment fan deposited on a floodplain
from a rupture in the levee of a river.
crumb—A soft, porous, more or less rounded soil
aggregate 1 – 5 mm in diameter.
cryptogams—Collective term which includes mosses,
algae, lichen and liverworts.
cutans—Coatings on ped surfaces, which may include clay
skins or coatings of sesquioxide, manganese, ferromanganese,
organic matter or carbonate.
D
D horizon—Layers below the solum which are not C
horizon and are not related to the solum or pedologic
organisation.
densipan—Earthy pan which is very fine sandy (0.02 -
0.05 mm). Fragments, both wet and dry, slake in water. Densipans
are less stable on exposure than overlying or underlying
horizons.
Dermosols—ASC Soil Order classification—Other soils
with B2horizons that have structure more developed
than weak throughout the major part of the horizon.
Desert Loams—GSG classification—Soils which have
moderate texture contrast with thin, loamy A horizons clearly
separated from structural clay B horizons, brown to red colour,
and alkaline reaction—commonly strongly so in the deeper
subsoil. Surface soil pH ranges from alkaline to neutral.
Devonian—Geological period 395 – 345 million years
ago.
diatreme—A small explosive volcanic intrusion comprised
of varying amounts and types of pyroclastic debris and
surrounding country rock.
diffuse boundary—Boundary >100 mm wide.
E
earthflow—A category of mass movement involving earth
materials flowing downslope like a viscous fluid. Displacement
varies from extremely slow to extremely rapid.
Earthy Sands—GSG classification—A predominantly sandy
soil with an earthy fabric and little texture differentiation
from topsoil to subsoil.
edaphic—Referring to soil factors affecting plant
growth.
Eocene—Geological epoch 54 – 38 million years ago.
Euchrozems—GSG classification—Red, strongly
structured clay soils with a somewhat lower clay content near
the surface. They resemble but are more alkaline than Krasnozems.
eutrophic—Base status is greater than 15 cmol(+)kg-1
clay.
F
fabric—The appearance of the soil material using a x10
hand lens. Differences in the presence or absence of peds, the
lustre, or lack thereof, ped surfaces, and the size and
arrangement of pores in the soil mass are noted. Descriptive
terms used are:
earthy fabric—The soil material is cohesive
and contains pores but few, if any, peds;
sandy fabric—The soil material consists of
closely packed sand grains which are weakly cohesive with few if
any peds;
rough-ped fabric—Peds are evident.
Characteristically, more than 50% of the peds are matt or
rough-faced;
smooth-ped fabric—Peds are evident.
Characteristically, more than 50% of the peds are glossy or
smooth-faced.
facies—The appearance or aspect of any rock; the sum
total of its characteristics. (stratigraphic facies—The
sum of the rock and fossil features of a sedimentary rock).
fan—A low cone of alluvial materials. The central point
lies at the mouth of a gully or ravine and the material is
spread out onto the adjoining plain.
faunal casts—Soil matter reworked by passing through
the digestive tracts of soil animals.
felspar or feldspar—Aluminosilicates of
potassium, sodium and calcium, and characterised by two
cleavages at nearly right angles. They are among the most
important constituents of igneous rock).
ferric horizon—One which contains more than 20% of
ferruginous nodules or concretions which are mostly uncemented,
and has a minimum thickness of 0.1m.
ferromanganiferous—Consisting of iron and manganese.
Ferrosols—ASC Soil Order classification—Soils with B2
horizons in which the major part has a free iron oxide content
greater than 5% Fe in the fine earth fraction (<2 mm). Soils
with a B2horizon in which at least 0.3 m has vertic
properties are excluded.
ferruginous cementation—The bonding of soil particles
into a hard mass by concentration of iron around a nucleus.
fibric—Fibrous organic material.
floc condition—Refers to the general flocculent or
aggregated appearance of the soil mass, especially when viewed
under a hand lens of about x10.
forest—Vegetation community consisting of trees to 30 m
tall generally with an understorey of smaller trees, shrubs,
grasses and herbs. Open-forest has a 30 - 70% canopy cover,
while closed-forest has a canopy cover of >70%. Tall forests
are forests in which the upper stratum height exceeds 30 m.
G
gley—The grey or greenish-grey colouration found in
soils. It is often produced under conditions of poor drainage,
giving rise to chemical reduction of iron and other elements.
Gleyed Podzolic Soils—GSG classification—Poorly
drained acid soils with strongly differentiated profiles,
including a bleached A2 overlying greyish or
yellowish B horizons.
gradual boundary—Boundary 50 - 100 mm wide.
granite—A granular igneous rock composed chiefly of
felspar (orthoclase) and quartz, usually with one or more other
minerals, as mica, hornblende, etc.
granodiorite—Plutonic rock consisting of potassium
felspar, quartz, plagioclase, biotite and hornblende.
Granodiorite is an intermediate between quartz, monzonite and
quartz diorite.
gravel—The amount (visual abundance estimate) of
gravel-sized (>2 mm) materials that occur on the surface and
in the A1 horizon and include hard (when moist),
coarse fragments and segregations of pedogenic origin.
gravelly—Over 60% of surface cover consists of gravel
(2 - 60 mm).
Great Soil Groups—See GSG.
Grey, Brown and Red Clays—GSG classification—These
form a broad group of soils whose common properties are
determined by their high clay contents. Typically, they are
moderately deep to very deep soils with uniform colour and
texture profiles, weak horizonation mostly related to structure
differentiation and some carbonates and/or gypsum in their
subsoils. They crack deeply on drying.
Grey-brown and Red Calcareous Soils—GSG classification—Shallow,
soft, powdery or weakly structured loams to light clays
containing finely divided carbonates throughout the solum and
showing little pedological differentiation. They are essentially
sedentary soils formed from highly calcareous rocks which
underlie them at various depths. Fragments of limestone are
commonly present.
Grey-brown Podzolic Soils—GSG classification—Duplex
soil with a clayey brownish blocky B horizon. A bleached A2
horizon may be present.
GSG—Great Soil Groups of Australia (as defined by Stace
et al 1968), described in terms of morphology, genesis
and land use.
gypsic horizon—One which contains more than 20% of
visible gypsum that is apparently of pedogenic origin and has a
minimum thickness of 0.2 m.
H
hard—A general term to indicate strength.
heath—Vegetation structure dominated by shrubs less
than 2 m tall, having a foliage cover of 30 - 70% (open-heath)
or 70 - 100% (closed-heath).
hobby farm—Type of land development, irrespective of
allotment size but usually relatively small, involving some form
of agricultural enterprise which is secondary to the owner's
main line of business.
Holocene—Present geological epoch which commenced 10
000 years ago.
horizon—A layer within the soil profile with
morphological characteristics and properties different from
layers below and/or above it.
Humic Gleys—GSG classification—Soils that are acid to
neutral, predominantly mineral soils with significant but widely
varying organic matter contents intimately incorporated in the
dark A horizons. These grade into subsoils marked by rusty and
ochreous streaks and mottles on a pale grey matrix. Below this
mottled horizon, the soil is typically grey to bluish-grey and
permanently waterlogged, but the watertable fluctuates,
periodically rising almost to the surface.
humose horizon—This is a humus-rich surface or
near-surface horizon that is 0.2m or more thick and has
insufficient organic carbon to qualify as organic material.
Humus Podzols—GSG classification—These soils have a
dark A1 horizon of organic accumulation, a light grey
or whitish A2 horizon and a dark grey to black,
dominantly humic B horizon overlying water-saturated and weakly
mottled mineral soil.
Hydrosols—ASC classification—Soils that are saturated
for at least 2-3 months in most years.
J
Jurassic—Geological period 295 - 135 million years ago.
K
Kandosols—ASC Soil Order classification—Other soils
that (i) have well-developed B2 horizons in which the
major part is massive or has only a weak grade of structure, and
(ii) have a maximum clay content in some part of the B2
horizon which exceeds 15%.
Krasnozems—GSG classification—Deep, red strongly
structured clays soils with clay content gradually increasing
with depth and weak horizon differentiation.
Kurosols—ASC Soil Order classification—Soils with a
clear or abrupt textural B horizon and in which the major part
of the upper 0.2 m o the B2 horizon (or the major
part of the entire B2 horizon if less than 0.2 m
thick) is strongly acid.
L
labile—A measure of weak plasticity used in a
consistence test.
laminae—Thin sedimentary layers which are generally
<5 cm thick.
Lateritic Podzolic Soils—GSG classification—Strong
texture contrast with thick, sandy A horizons overlying mottled
yellow-brown and red clay B horizons, an horizon of nodular
pisolitic, or massive ironstone in the base of the A2
and upper B horizon, a thick zone of coarsely mottled white, red
and yellow clay below the B horizon grading into dominantly
white clay above the kaolinised parent rock, and acid reaction
throughout the profile.
lenticular—Lens-shaped soil peds.
Lithosols—GSG classification—A shallow soil showing
minimal profile development and dominated by the presence of
weathering rock and rock fragments. Lacking horizons other than
an A1 (one layer only).
loam—A medium, textured soil of approximate composition
10 - 25% clay, 25 - 50% silt and <50% sand.
lower order stream—Streams close to source; none to few
tributaries.
M
macropores—Spaces in soil fabric, generally <2 mm in
diameter.
manganic horizon—One which contains more than 20%
(visual abundance estimate) of black manganiferous nodules or
concretions which are mostly uncemented, and has a thickness of
0.1m. Most nodules also contain some iron.
mangans—Cutans composed of manganese oxides.
massive—The condition of a soil layer in which the
layer appears as a coherent or solid mass largely devoid of peds.
matrix—The smaller grainsize material, typically a
cementing agent within a soil or rock in which larger particles
are embedded.
megaxenolith—Large rock fragments from a different type
of rock that are imbedded in a granitic rock.
melacic horizon—Same as melanic horizon but pH is less
than 5.5 and there is no structure requirement.
melanic horizon—Dark surface (black when moist) of
near-surface horizon that has insufficient organic carbon to
qualify as a humose horizon and has little, if any, evidence of
stratification. pH is greater than 5.5.
mottled horizon—A horizon in which mottle abundance is
greater than 10% (visual abundance estimate) and contrast
between colours is distinct and prominent.
mottling—The presence of more than one soil colour in
the same soil horizon, not including different nodule or cutan
colours.
N
Neutral to Alkaline Peats—GSG classification—These
peats may be black and highly granular, dark brown and fibrous,
or of some intermediate character and range in depth from about
30 cm to many cm. Lenses of shells and patches of soft
carbonates sometimes occur irregularly within the peat and
occasionally on the surface.
nodule—A small concretionary deposit usually of
sesquioxides or carbonates, usually hard.
Non-calcic Brown Soils—GSG classification—Very
similar to Red-brown Earths but without an A2
horizon. They have a carbonate-free solum and a neutral to
slightly alkaline (with lower base saturation) B horizon; and
are also generally thinner soils, varying from about 40 – 80
cm deep.
O
Oligocene—Epoch of the tertiary period, from 38 - 22.5
million years ago.
Ordovician—Geological period 525 – 440 million years
ago.
Organosols—ASC Soil Order classification—Soils that
are not regularly inundated by saline tidal waters and have more
than 0.4m of organic materials in the upper 0.8 m either
extending down from the surface or cumulatively; or have organic
materials extending from the surface to a minimum depth of 0.1 m
directly overlying rock or other hard layers.
P
palaeolake—Lake extant during a prior geological
period.
pan—A hardened and/or cemented horizon in or below the
soil profile.
parna—Aeolian-deposited clay particles whose source is
believed to be the rivers and lakes of the Lake Eyre and
Murray-Darling Basins.
peat—(i) fibric peat—undecomposed or
weakly decomposed organic material; (ii) hemic peat—moderately
to well-decomposed organic material; (iii) sapric peat—strongly
to completely decomposed organic material.
peaty horizon—This is a surface or near-surface layer
of organic materials at least 0.2m thick overlying mineral soil
and which does not qualify as an Organosol.
Peaty Podzols—GSG classification—Soils consisting
essentially of some depth of acid fibrous peat or sandy peat
overlying sandy mineral soil that has most of the features of
humus podzols but generally lacks a distinct A2
horizon.
ped—An individual, natural soil aggregate.
ped shape—Refers to the shape of natural soil
aggregates. Descriptive terms used are:
platy—The soil particles are flat or plate-like;
prismatic—The soil particles are prism-shaped
with well-defined flat surfaces;
columnar—This ped shape is similar to prismatic, but
the peds are larger and their tops are domed;
polyhedral—Interlocking peds with many re-entry
angles;
angular blocky—Soil particles are approximately
cubic with six relatively flat, equal faces. Edges are angular;
sub-angular blocky—This ped shape is similar
to angular blocky, but the edges of peds are rounded;
granular—These peds are spheroids or polyhedrons
having planar or curved surfaces which are relatively
non-porous.
pedal—Describes a soil in which some or all of the soil
material occurs in the form of peds in the moist state.
pedality—Refers to the relative proportion of peds in
the soil (as strongly pedal, weakly pedal or non-pedal).
perched watertable—The surface of a local zone of
saturation held above the main body of groundwater by an
impermeable layer, usually clay, and separated from it by an
unsaturated zone.
petroferric horizon—Ferruginous or ferromanganiferous
nodules or concretions cemented in place into indurated blocks
or large irregular fragments.
petroreticulite horizon—A reticulate horizon that is
always indurated in the greater part both before an after
exposure.
phenocrysts—Large crystals set in a fine-grained ground
mass.
phyllite—Fine-grained low-grade metasedimentary rock
intermediate in metamorphic-grade between a slate and a schist.
pisolitic—Comprising concentric nodules.
plant available waterholding capacity—see available
waterholding capacity.
plastic—Describes soil materials which are in a
condition that allows them to undergo permanent deformation when
force is applied without appreciable volume change or elastic
rebound or without rupture.
Pleistocene—First epoch of the Quaternary period, from
2 million years ago to 10 000 years ago.
Podosols—ASC Soil Order classification—Soils with B
horizons dominated by the accumulation of compounds of organic
matter, aluminium and/or iron.
podosol diagnostic horizon—Various B horizons
consisting of illuvial accumulations of amorphous organic
matter-aluminium and aluminium-silica complexes, with or without
iron in various combinations.
Podzols—GSG classification—Acid sandy soils with
strongly differentiated horizons including a bleached horizon
above a coffee coloured pan and coloured subsoil.
point bar—Elongated, gently to moderately inclined low
ridge within the stream channel built up by channelled stream
flow.
Prairie Soils—GSG classification—Moderately deep,
mildly acid to mildly alkaline soils with thick, dark,
moderately structured topsoils.
profile—The face of soil exposed in a vertical section.
Q
Quaternary—Period of geological time covering the
Holocene plus the Pleistocene. Up to 2.6 million years ago.
R
Red and Brown Hardpan Soils—GSG classification—Soils
have simple, shallow to moderately deep profiles of red earthy
and massive soil sharply overlying an indurated pan resulting
from silica cementation and clay deposition.
Red Calcareous Soils—GSG classification—see
Grey-brown and Red Calcareous Soils.
Red Clays—GSG classification—See Grey, Brown and Red
Clays.
Red Earths—GSG classification—Massive, reddish sandy
profiles with a gradual increase in clay content with depth over
a diffuse to gradual boundary.
Red Podzolic Soils—GSG classification—Strongly
differentiated duplex soils with light to medium textured A1
horizon over a pale or bleached A2 over a
reddish, firm to friable B horizon with generally polyhedral
structure.
Red-brown Earths—GSG classification—The
characteristic features of these soils are grey-brown to
red-brown loamy A horizons, weakly structured to massive, an
abrupt to clear boundary between A and B horizons, and brighter
brown to red clay B horizons with well-developed medium
prismatic to blocky structure.
regolith—Mantle of loose and weathered material
overlying the bedrock.
relict landform—landform in which the formative
geomorphological processes are no longer active.
Rendzinas—GSG classification—Shallow to very shallow
soils formed from limestones and marls; typically they are
black, very dark brown or dark grey clay loams or light clays of
strong, very fine crumb to granular structure and lose, soft
consistence which usually continues throughout their thin sola.
reticulate horizon—This is intended for strongly
developed reddish, yellowish and greyish or white, more or less
reticulately mottled horizons that can be hand-augured or cut
with a spade. Ferruginous nodules or concretions may be present.
rhyolite—Fine-grained acidic volcanic rock
mineralogically similar to granite, but possessing less quartz.
Rudosols—ASC Soil Order classification—Soils with
negligible pedologic organisation. They are usually young soils
in the sense that the soil forming factors have had little time
to pedologically modify parent rocks or sediments. The component
soils can vary widely in terms of texture and depth; many are
stratified and some are highly saline.
S
saline discharge—Underground saline water which flows
or seeps out at the soil surface; salinity may be concentrated
by subsequent evaporation.
sapric—Non-fibrous organic material.
screen—Remnant of Ordovician metasedimentary ‘country’
rocks (older rocks into which granitics intruded) which separate
different granitic plutons, but also used here to describe
steeply dipping metasedimentary rocks intruded by granitics, as
occurs near metasediment-granitic boundaries. Screens may be
kilometres wide to only a few metres wide.
semi-arid—Climate of 250 – 500 mm annual rainfall.
sesquioxide—Oxides of aluminium and iron.
sharp boundary—Boundary <5 mm wide
sheet erosion—The removal of the upper layers of soil
by raindrop splash and/or runoff.
shield volcano—Broad, gently sloping surface consisting
of overlapping basalt flows.
Siliceous Sands—GSG classification—Deep profile of
sands to clayey sands, with no horizon differentiation except
for a darker A1 horizon.
silt—Fine soil particles in the size range 0.02 - 0.002
mm.
Silurian—Geological period 440 – 395 million years
ago.
single-grained—The soil occurs as a loose, incoherent
mass of individual particles (as in sands).
skeletal soils—Thin soils.
slaking—The partial breakdown of soil aggregates in
water due to the swelling of clay and the expulsion of air from
pore spaces.
sodicity—A measure of exchangeable sodium in the soil.
High levels adversely affect soil stability, plant growth and/or
land use.
Sodosols—ASC Soil Order classification—Soils with
strong texture contrast between A horizons and sodic B horizons
which are not strongly acid.
Solodic Soils—GSG classification—See Solodised
Solonetz and Solodic Soils.
Solodised Solonetz and Solodic Soils—GSG classification—Soils
with strong texture contrast, well-developed bleached A2
horizon over an alkaline medium to coarse angular blocky
structure of typically strong consistency.
Solonchaks—GSG classification—Soils dominated by salt
accumulation and which show one or more of the following; salty
encrustations; surface flaking; polygonal cracking of the
surface; powdery structure; lack of normal plant growth except
salt tolerant species.
Solonetz Soils—GSG classification—Soils with
prominent texture differentiation between neutral to slightly
alkaline, loamy topsoils and strongly alkaline, clay subsoils.
Solonised Brown Soils—GSG classification—Soils
characterised by large amounts of calcareous material in the
profile both in the fine earth fraction and as soft and hard
segregations consisting of calcium and magnesium carbonates, but
usually the calcium is predominant.
Soloths—GSG classification—Acid soils with strong
texture contrast between pale topsoil and clay subsoil with
coarse blocky or columnar structure.
solum—The upper part of a soil profile above the parent
material in which current processes of soil formation are
active. This is where the living roots and other plant and
animal life characteristics are exhibited.
stone line—A layer of gravel within a soil profile.
strongly coherent B horizon—These are Podosol B
horizons in which the consistence strength ranges from very firm
to strong throughout, or they contain sub-horizons with these
properties. Included are pan-like materials that have been
variously described as orstein, coffee rock or sandrock.
structure—Is concerned with the arrangement of all soil
particles and refers to the distinctness, size, shape and
condition of the peds. The degree of structural distinctness is
referred to as grade of pedality. Descriptive terms used are:
single-grained—The soil occurs as a loose,
incoherent mass of individual particles (as in sands);
massive—The soil occurs as a coherent mass
with no distinct arrangement of soil particles;
weak pedality—The soil contains peds which are
barely observable;
moderate pedality—The soil contains peds
which can be identified but are not distinct;
strong pedality—The soil contains peds which
are clearly observable.
sub-humid—Climate of 500 – 1500 mm annual rainfall.
sub-plastic—A soil which appears to become more clayey
with prolonged kneading. They are usually red, well structured
and well-drained.
sulfidic materials—A subsoil, waterlogged, mineral or
organic material than contains oxidisable sulfur compounds,
usually iron disulfide (eg, pyrite, FeS2) that has a
field pH of 4 or more but which will become extremely acid when
drained.
sulfuric materials—Soil material that has a pH less
than 4 when measured in dry season conditions as a result of the
oxidation of sulfidic materials.
surface condition—Describes the actual surface
condition of the exposed soil surface:
gravelly—Over 60% of surface cover consists of
gravel (2 – 60 mm);
hardsetting—Soil is compact and hard and
appears to have apedal structure when the soil dries out;
loose—Soil which is not cohesive;
friable—Easily crumbled or cultivated;
self-mulching—Loose surface mulch of very small peds
forms when soil dries out;
seasonal cracking—Shrinking clay soils which shrink
when dry, expand when wet and exhibit wide cracks in the dry
state.
swale—A linear level-floored open depression excavated
by wind or formed by the build-up of two adjacent ridges.
Typically associated with the depression between two adjacent
sand dunes.
T
tenic B horizon—A usually weakly developed B horizon of
texture and/or colour and/or structure and/or presence of
segregations of pedogenic origin (including carbonate).
Tenosols—ASC Soil Order classification—Soils with
generally only weak pedologic organisation apart from the A
horizons.
Terra Rossa Soils—GSG classification—Dominantly red
soils formed on limestone or highly calcareous parent materials.
Tertiary—Period of geological time, 2 – 65 million
years before present.
texture—A measure of the behaviour of a small handful
of soil when moistened and kneaded into a ball and then pressed
out between the thumb and forefinger.
tonalite—A quartz-diorite igneous rock intermediate in
quartz content between a diorite and a granodiorite.
topsoil—A part of the soil profile, typically the A1
horizon, containing material which is usually darker, more
fertile and better structured than the underlying layers.
transferral—Deep deposits of mostly eroded parent
materials washed from areas directly upslope.
travertine—Calcium carbonate precipitated from
groundwater.
Triassic—Period of geological time, 180 – 230 million
years before present.
tuff—Volcanic rock of compacted medium to fine-grained
pyroclastic material.
V
varved shales—Shales deposited from melted ice in a
lake in which the depositional layers appear in pairs; each pair
represents a seasonal deposit.
vertic properties—Soil material with a clayey field
texture or 35% or more clay which cracks strongly when dry and
has slickensides and/or lenticular peds.
Vertosols—ASC Soil Order classification—Clay soils
with shrink-swell properties that exhibit strong cracking when
dry and at depth have slickensides and/or lenticular structural
aggregates. Although many soils exhibit gilgai microrelief, this
feature is not used in their definition.
W
Wiesenboden—GSG classification—Dark clay to clay loam
soils with uniform to gradational texture profiles and varying
development of gley features in the deeper subsoil due to
intermittent partial saturation associated with seasonal seepage
and perched water.
wilting point—Point at which the rate of moisture loss
from the leaf surface is greater than the uptake from plant
roots. The wilting point differs in various soil types according
to texture.
woodland—Vegetation structure dominated by trees where
canopy foliage covers 10 – 30% of the ground area.
X
Xanthozems—GSG classification—Predominantly yellow,
friable, strongly-structured clay soils with moderate horizon
differentiation and gradational texture profiles.
xenolith—Rock fragments from a different type of rock
that are imbedded in a granitic rock.
Y
Yellow Earths—GSG classification—Yellow equivalent of
Red Earths.
Yellow Podzolic Soils—GSG classification—Strongly
differentiated duplex soils with light to medium textured A1
horizon over a pale A2 horizon over a yellowish, firm
to friable B horizon with generally polyhedral structure.
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