forestry commission soil classification - lotc · a soil type defines a soil within a group of...
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Soil Classification
AK & BR
3.44b
Why look at soil?
Because soil and its constituents are the base
material for growing trees.
There is a need for an objective site classification of United Kingdom soil / site types, upon which the growing and management of trees can be based.
History
Why a Forestry Commission soil classification?
FC soil classification – Soil Classes
Soils with well
aerated subsoil
Soils with
poorly aerated
subsoil
Flushed
peatlands
Unflushed
peatlands
Man-made
soils mining / quarry spoil, brownfield sites etc.
Rankers and
Skeletal soils bedrock present at < 30cm
Littoral soils adjacent to the coast, sands and gravels
main soil classes
minor soil classes
Typical soil constituents
30-20% WATER
COMPONENT
20-30% AIR
COMPONENT
45% MINERAL
COMPONENT
5% ORGANIC COMPONENT
What creates a soil?
• Parent material - (type of rock)
• Climate - (heat, water, wind)
• Organisms - (bugs, insects, fungi, bacteria)
• Topography - (landform)
• Time
Parent Material
The parent material is the material from which a
soil is formed, not necessarily the bedrock of
a site.
The geographic position of the parent material affects
the potential water holding capacity, fertility and
texture of a soil.
Soil particles - texture
SAND: coarse rough granular particles
SILT: smooth spherical particles
CLAY: flat, plate-like particles
Soil texture
triangle
Clay
Silt
Sand
Soils with well
aerated subsoil
Soils with
poorly aerated
subsoil
Flushed
peatlands
Unflushed
peatlands
3 Podzols
4 Ironpan soils
12 Calcareous soils
5 Ground-water gley soils
6 Peaty surface-water gley soils
7 Surface-water gley soils
1 Brown earths
8 Juncus (or basin) bogs
9 Molinia (or flushed blanket) bogs
10 Sphagnum (flat or raised) bogs
11 Calluna, Eriophorum, Trichophorum (or unflushed blanket) bogs
14 Eroded bogs
2 Man-made soils 13 Rankers and Skeletal soils 15 Littoral soils
FC soil classification – Soil Groups
A LAYER CAKE!
Soil Horizons
A - Top soil (mineral with incorporated organic material)
B – Mineral soil (altered parent material)
C – Parent material (unaltered)
O – Organic material (humus or peat layers)
L – Litter (fresh litter from previous growth season)
E – Elluvial (removed organic, clay and oxides)
Generic soil processes
Podzolisation (ironpan formation)
Gleying
Build-up of partially decomposed vegetation
(humus/peat)
Typical brown earth
Slight podzolisation
Slight gleying
Slight build up of partially
decomposed vegetation
(humus/peat)
Rooting is unrestricted
by anaerobic conditions
Brown earth
Soils with brownish or reddish colours,
free drainage and good aeration and
moderate or strong acidity, throughout
the profile. Humified organic matter is
incorporated into the mineral soil to give
a dark brown topsoil (A horizon). There
is no E horizon. The B horizon is
distinguished from the underlying C by a
richer brown colour due to weathering
and the residual accumulation of iron
oxides (Bw horizon).
Brown earth
A
B
C
O
Soil
Moisture and
Nutrient grid
Very Poor Poor Medium Rich Very Rich Carbonate
mor mor, modermoder,
oligomull
oligomull,
eumulleumull eumull
Very
Dry
Mod.
Dry
Sl. D
ryF
resh
Mois
tV
. M
ois
tW
et
Very
Wet
Soil Nutrient Regime
Humus form
Soil
Mois
ture
Regim
e
Rankers and shingle
Gravelly or
sandy podzols
and ironpan
soils
Gravelly or sandy
brown earths
Loamy podzols
and ironpan
soils
Podzolic gleys
and peaty
ironpan soils
Unflushed
peaty gleys
and deep peats
Loamy brown
earths
Brown gleys
Surface-water
gleys
Flushed peaty
gleys and deep
peats
Rendzinas
Loamy brown
earths of high
base status
Brown gleys of
high base
status
Surface-water
gleys of high
base status
Humic gleys of
high base status
and fen peats
Calcareous
brown
earths
Calcareous
brown
gleys
Calcareous
surface-
water gleys
Brown earth
Podzol soil
Acidic soil conditions
Oxide leaching
Humus movement
Humus and oxide deposition
Possible ironpan formation
Possible surface gley
formation
Possible subsequent peat
formation
Podzol
Podzols are free draining, well aerated,
strongly acid soils with a surface
accumulation of raw humus, an Ea
horizon from which iron oxides have been
removed, and B horizons in which
translocated humus or iron oxides have
been deposited. The A horizon, which
may not be well developed, consists of a
mixture of blackish humus particles and
bleached sand grains. The Ea horizon
consists largely of bleached sand grains
and is whitish in colour. Both A and E
horizons have a friable consistence.
Podzol
B
C
O
E
A
Podzol soil
Ironpan soil
The characteristic features of this group are an Eg
horizon underlain by a thin ironpan (Bf horizon).
The Eg horizon has a grey colour often with a
yellowish or greenish hue and ochreous or rusty
mottles or streaks. These gley like symptoms are
caused by reduction and segregation of iron,
during frequent periods of waterlogging and
anaerobism. There is a surface accumulation of
black greasy peat but this can be as little as a few
centimetres thick or as much as 45 cm, the
maximum allowed in the group. The subsoil,
beneath the ironpan, usually lacks gleying
symptoms and is not affected by waterlogging or
anaerobism. Ironpan soils are strongly acid
throughout the profile. The ironpan normally
passes through stones, depending on their
porosity, and also forms a conspicuous coating on
the stones.
Ironpan
B
C
O
E
A
Bf
Soil
Moisture and
Nutrient grid
Very Poor Poor Medium Rich Very Rich Carbonate
mor mor, modermoder,
oligomull
oligomull,
eumulleumull eumull
Very
Dry
Mod.
Dry
Sl. D
ryF
resh
Mois
tV
. M
ois
tW
et
Very
Wet
Soil Nutrient Regime
Humus form
Soil
Mois
ture
Regim
e
Rankers and shingle
Gravelly or
sandy podzols
and ironpan
soils
Gravelly or sandy
brown earths
Loamy podzols
and ironpan
soils
Podzolic gleys
and peaty
ironpan soils
Unflushed
peaty gleys
and deep peats
Loamy brown
earths
Brown gleys
Surface-water
gleys
Flushed peaty
gleys and deep
peats
Rendzinas
Loamy brown
earths of high
base status
Brown gleys of
high base
status
Surface-water
gleys of high
base status
Humic gleys of
high base status
and fen peats
Calcareous
brown
earths
Calcareous
brown
gleys
Calcareous
surface-
water gleys
Podzols and Ironpans
Typical surface-water gley
Waterlogged soil becomes
anaerobic (without oxygen).
Soil loses bright, ochreous
appearance and takes on a
grey / black or mottled grey
and yellow / blue / pink
appearance.
Rotten stones are found in
the gleyed layers.
Rooting is restricted by the
anaerobic conditions.
Surface-water gley
A distinct topsoil or Ag horizon, grey coloured
with rusty streaks, and some 15 - 25 cm thick,
overlies a mottled grey and yellow subsoil, the
Bg horizon. At a depth of about 100 cm the
mottling becomes less distinct, in the BCg
horizon, and within another 50 cm the colour
becomes almost uniform in the C horizon. The
profile may be attenuated by bedrock so that a
true C horizon may be absent. Textures in the
type are finer than sandy clay loam at least in the
Bg and BCg horizons although the Ag horizon is
usually loamy and the C horizon is usually less
clayey because it is less weathered.
Surface-water gley
B
C
O
A
Soil
Moisture and
Nutrient grid
Very Poor Poor Medium Rich Very Rich Carbonate
mor mor, modermoder,
oligomull
oligomull,
eumulleumull eumull
Very
Dry
Mod.
Dry
Sl. D
ryF
resh
Mois
tV
. M
ois
tW
et
Very
Wet
Soil Nutrient Regime
Humus form
Soil
Mois
ture
Regim
e
Rankers and shingle
Gravelly or
sandy podzols
and ironpan
soils
Gravelly or sandy
brown earths
Loamy podzols
and ironpan
soils
Podzolic gleys
and peaty
ironpan soils
Unflushed
peaty gleys
and deep peats
Loamy brown
earths
Brown gleys
Surface-water
gleys
Flushed peaty
gleys and deep
peats
Rendzinas
Loamy brown
earths of high
base status
Brown gleys of
high base
status
Surface-water
gleys of high
base status
Humic gleys of
high base status
and fen peats
Calcareous
brown
earths
Calcareous
brown
gleys
Calcareous
surface-
water gleys
Surface-water gley
Peaty gley
Waterlogged soil
becomes anaerobic
Litter breakdown is
slowed by anaerobic
conditions
Build up of partially
decomposed vegetation
less than 45cm deep
Rooting is restricted by
the anaerobic conditions
Peaty gley
This is a soil with impeded drainage and surface peat
accumulations between 5 - 25cm thickness. The peat is
black or dark brown and amorphous or almost so. When
partially dried the peat shows a granular or fine blocky
structure. Beneath the peat the Ahg horizon is black or
dark grey and usually less than 10 cm thick. The Eg
horizon may be well developed, with pale grey colour
dominant and ochreous mottling associated with root
channels and soft weathered stones. The Bg horizon has
a roughly 50:50 mixture of grey and yellow or ochreous
mottling. Towards the bottom of the Bg horizon, which
may be termed the BCg horizon, the mottling becomes
less prominent, usually because the ochreous colour
becomes less yellow and more khaki or olive and because
the grey colour becomes darker. In the C horizon the
colours become less distinct and eventually merge, i.e. the
original colour of the parent material is retained. Textures
in the type are finer than sandy clay loam in the Bg
horizon.
Peaty gley
B
C
O
A E
Soil
Moisture and
Nutrient grid
Very Poor Poor Medium Rich Very Rich Carbonate
mor mor, modermoder,
oligomull
oligomull,
eumulleumull eumull
Very
Dry
Mod.
Dry
Sl. D
ryF
resh
Mois
tV
. M
ois
tW
et
Very
Wet
Soil Nutrient Regime
Humus form
Soil
Mois
ture
Regim
e
Rankers and shingle
Gravelly or
sandy podzols
and ironpan
soils
Gravelly or sandy
brown earths
Loamy podzols
and ironpan
soils
Podzolic gleys
and peaty
ironpan soils
Unflushed
peaty gleys
and deep peats
Loamy brown
earths
Brown gleys
Surface-water
gleys
Flushed peaty
gleys and deep
peats
Rendzinas
Loamy brown
earths of high
base status
Brown gleys of
high base
status
Surface-water
gleys of high
base status
Humic gleys of
high base status
and fen peats
Calcareous
brown
earths
Calcareous
brown
gleys
Calcareous
surface-
water gleys
Peaty gley
A soil type defines a soil within a group of soils
with similar characteristics.
Upland brown earths have a slightly gleyed layer at the top (1u).
Many soils are fully classified at the type level.
FC soil classification – Soil Types
Soils with well
aerated subsoil
3 Podzols
4 Ironpan soils
12 Calcareous soils
1 Brown earths
1 Typical brown earth
1d Basic brown earth
1u Upland brown earth
1z Podzolic brown earth
3 Typical podzol
3m Hardpan podzol
4 Typical ironpan soil
4z Podzolic ironpan soil
4b Intergrade ironpan soil
12a Rendzina
12b Calcareous brown earth
12t Argillic brown earth
FC soil classification – Soil Types
Soil
Moisture and
Nutrient grid
Very Poor Poor Medium Rich Very Rich Carbonate
mor mor, modermoder,
oligomull
oligomull,
eumulleumull eumull
Very
Dry
Mod.
Dry
Sl. D
ryF
resh
Mois
tV
. M
ois
tW
et
Very
Wet
Soil Nutrient Regime
Humus form
Soil
Mois
ture
Regim
e
Rankers and shingle
Gravelly or
sandy podzols
and ironpan
soils
Gravelly or sandy
brown earths
Loamy podzols
and ironpan
soils
Podzolic gleys
and peaty
ironpan soils
Unflushed
peaty gleys
and deep peats
Loamy brown
earths
Brown gleys
Surface-water
gleys
Flushed peaty
gleys and deep
peats
Rendzinas
Loamy brown
earths of high
base status
Brown gleys of
high base
status
Surface-water
gleys of high
base status
Humic gleys of
high base status
and fen peats
Calcareous
brown
earths
Calcareous
brown
gleys
Calcareous
surface-
water gleys
Deep peat
Man-made
soils
Rankers and
Skeletal soils
13 Rankers and Skeletal soils
2 Man-made soils
2s Mining spoil, stony or coarse textured
2m Mining spoil, shaly or fine textured
13b Brown ranker
13g Gley ranker
13p Peaty ranker
13z Podzolic ranker
13r Rock
13s Scree
FC soil classification – Soil Types
13c Ranker complex
Littoral soils 15 Littoral soils
15s Shingle
15d Dunes
15e Sand with deep water-table
15i Sand with moderately deep water-table
15g Sand with shallow water-table
15w Sand with very shallow water-table
FC soil classification – Soil Types
A soil phase further describes a specific soil
type’s potential silvicultural characteristics.
Soil phases are only applied to the main mineral and shallow peaty soil types (peat < 45cm deep).
Multiple phases maybe combined to describe a soil type.
They are a flexible, yet precise description.
FC soil classification – Soil Phases
Soil Phase suffixes used with Soil Types 1-7z, 12b & 12t
Suffix Name Description
a shallow predominantly 30-45cm soil to bedrock (0-45cm for man-
made soils)
c cultivated considerable alteration to physical or chemical properties or
to vegetation by former agricultural use
e ericaceous vegetation contains sufficient Calluna (dominant to frequent)
to become a weed problem after planting
f flushed considerable enrichment with nutrients from flushing water,
as indicated by the presence and vigour of tall Juncus sp.,
Deschampsia caespitosa or Molinia
g slightly
gleyed
subsoil slightly mottled or with grey patches
h humose topsoil contains between 8 and 30% organic matter
i imperfectly
aerated
grey colouration is less prominent than usual, but doesn’t
quite qualify as type 7b
k calcareous pH > 7 in A, E or B horizons
Soil Phase suffixes used with Soil Types 1-7z, 12b & 12t
Suffix Name Description
l loamy texture throughout is not finer than sandy clay loam
p peaty presence of an O horizon (containing > 25% organic matter)
exceeding varying thickness (depending on soil type):
3 / 5 5 – 45cm
6 / 6z 25 – 45cm
4 / 4z 15 – 45cm
s extremely
stony
stones occupy more than 35% of soil volume
v alluvial soil developed in recent alluvium (river sediment) of sandy or
coarse loamy texture
x indurated has strongly indurated material within 45cm of the soil
surface; where the induration is moderately developed or at
45 – 60cm use (x)
z podzolic presence of bleached Ea horizon or humus rich Bh horizon
If more than one suffix is used they are placed in the order: v l p h z x g i s a f k c e
Intergrades and phases
Podzolic peaty gley i.e. very poor and wet
Podzol i.e. very poor and slightly dry
Podzol with peaty and gleyed phase
i.e. very poor and moist
Critical depths in soil profiles
Peat depth:
< 5cm mineral soil, no phase
5 – 25cm 7 become 6
5 – 45cm 3 and 5 become 3p and 5p
15 – 45cm 4, 4z and 4b become 4p, 4zp and 4bp
25 – 45cm 6 and 6z become 6p and 6zp
> 30cm 13p becomes deep peat
> 45cm deep peat
Depth to bedrock:
< 30cm ranker or rendzina
30 – 45cm shallow phase (a)
Depth to induration:
< 45cm indurated phase x, or (x) if moderate induration
45 – 60cm indurated phase (x)
Forest Grid reference
GPS waypoint no.
Soil type & phase Surveyor
Texture Date
Horizon details
and depth (cm)
(from the
surface)
O Stoniness (% volume)
A Humus type
E Root depth
B ESC Soil Moisture
Regime
C ESC Soil Nutrient
Regime
FC soil classification recording form