2 Soil Description

Soil Description Form
Field Procedure
Completing the Form
1.	Surveyor
2.	Plot Number
3.	Bedrock Type
4.	Coarse Fragment Lithology
5.	Terrain Classification
6.	Soil Classification
7.	Humus Form
8.	Hydrogeomorphic Units
9.	Rooting Depth
10.	Rooting Zone Particle-Size
11.	Root Restricting Layer
12.	Water Source
13.	Seepage Water Depth
14.	Drainage Class and Soil Moisture Subclass
15.	Flooding Regime
Organic Horizons and Layers
16.	Horizon/Layer
	Codes for master organic horizons Codes for subordinate organic horizons Lowercase modifiers Codes for organic layers Tiers
17.	Depth
18.	Fabric
	Structure von Post scale of decomposition
19.	Mycelial Abundance
20.	Fecal Abundance
21.	Roots
22.	pH
23.	Comments section
	Consistence
	Character
Mineral Horizons and Layers
24.	Horizon/Layer
	Codes for major horizons Codes for layers Lowercase modifiers Mineral diagnostic horizons
25.	Depth
26.	Colour
27.	Texture
28.	Percent Coarse Fragments
29.	Roots
30.	Structure
31.	pH
32.	Comments
	Mottling Clay films Effervescence Horizon porosity
33.	Profile diagram
34.	Notes
Appendices
2.1	Codes for Soil Orders, Great Groups and Subgroups
2.2	Key to Soil Orders
2.3	Key to Humus Forms
2.4	Key to Soil Texture
Tables
2.1	Sedimentary rock codes
2.2	Igneous rock codes
2.3	Metamorphic rock codes
2.4	Terrain texture codes
2.5	Surficial material codes
2.6	Surface expression codes
2.7	Geomorphological process codes
2.8	Qualifier codes
2.9	Codes for humus orders and groups
2.10	Codes for hydrogeomorphic systems
2.11	Codes for hydrogeomorphic subsystems
2.12	Rooting zone particle size classes
2.13	Codes for root-restricting layers
2.14	Water source codes
2.15	Drainage classes and codes
2.16	Soil moisture subclasses and codes
2.17	Codes for frequency of flooding
2.18	Codes for duration and timing of flooding
2.19	Guidelines for differentiating between upland and wetland organic horizons
2.20	Degree of aggregation codes
2.21	Kind of aggregation codes
2.22	von Post decomposition classes
2.23	Mycelial abundance classes and codes
2.24	Fecal abundance classes and codes
2.25	Root abundance and size classes and codes (organic layer)
2.26	Codes for methods of pH measurement
2.27	Consistency classes and codes
2.28	Character classes and codes
2.29	Colour aspects and codes for mineral soils
2.30	Size classes and type codes for coarse fragments
2.31	Root abundance and size classes and codes (mineral horizon)
2.32	Codes for kind and class of soil particle structure
2.33	Abundance and size codes for mottles
2.34	Contrast codes for mottles
2.35	Clay film frequency classes
2.36	Clay film thickness classes
2.37	Codes to describe degree of effervescence
2.38	Mineral horizon porosity classes
Figures
2.1	Relationship of size and roundness of the clastic textural terms
2.2	Rooting zone particle size classes
2.3	Major kinds of soil fauna
2.4	Soil texture triangle
2.5	Diagrammatic representation of soil structure
2.6	Example of profile diagram

Soil Description Form

Field Procedure

Getting Started

1.	Locate plot boundaries, asses variability, select pit locations(s).
2.	Excavate pit (generally 50-75 cm in depth) leaving the face and sides undisturbed around the ground surface.
3.	While excavating, observe:
	organic horizon depths and fabric; mineral horizon depths, colours, structure, and textural changes; percentage and shape of coarse fragments; rooting abundance, depth, and restrictions; and mottling, water seepage, or water table.
4.	Lay out notes, forms, and soil description tools.
5.	Clean off face from top to bottom (and photograph if required).
	Note horizon changes and mark with knife indentations or golf tees. Collect soil texture samples from bottom to top and put aside.

Record and Classify (see tab numbers on sample form, above)

1	Designate horizons on form (organic and mineral horizons/layers).
	For each horizon (depending on survey objectives/requirements):
	Record average starting and ending depths. For organic horizon, record fabric, mycelia and fecal abundance, rooting, and pH. For mineral horizons, hand-texture soil samples and determine colours. Record percent and shape of coarse fragments, rooting, structure, and pH. Note important observations in comments (e.g. soil fauna, mottles, clay films, etc.). Confirm original horizon designations.
2	Sketch a profile diagram to approximate scale.
3	Record:
	rooting depth, particle size, and restricting layer water source, seepage depth, drainage class, and flooding regime
4	Classify:
	bedrock geology and coarse fragment lithology type(s) terrain unit(s), soil pedon, humus form, and hydrogeomorphic unit
5	Use the "Notes" section to summarize or describe important soil features not otherwise collected on the form, or are significant to the study, classifications, or management interpretations

Check and Integrate

Check the form to ensure there are no missing data, and then (under most circumstances) fill in the pit. Strike through any fields that were not assessed. Integrate the soil data with other site factors to determine and record the soil moisture and soil nutrient regimes on the site description form.

Completing the Form

Numbered items below refer to circled numbers on the Soil Description Form shown at the beginning of this section. See "Field Procedure" for a recommended sequence for completing the form.

1. Surveyor

Indicate the first initial and last name of the person(s) who described and classified the soil profile.

2. Plot Number

Record the plot number from the top of the Site Description Form.

3. Bedrock Type

Record general or specific codes (see Tables 2.1, 2.2, 2.3) for up to three rock types in the underlying bedrock, in order of dominance if possible. This is particularly important on sites with shallow soils or bedrock exposure.

TABLE 2.1. Sedimentary rock codes

	General	Code	Specific	Code
Clastic, calcareous	Fine grained	kf	Calcareous Siltstone Calcareous Mudstone Calcareous Shale	kz kd kh
	Medium grained	km	Calcareous Greywacke Calcareous Arkose Calcareous Sandstone	kg ka ks
	Coarse grained	kc	Calcareous Conglomerate Calcareous Breccia	kn kb
Clastic, non-calcareous	Fine grained	uf	Siltstone Mudstone Shale	zl md sh
	Medium grained	um	Sandstone Greywacke Arkose	ss gk ak
	Coarse grained	uc	Conglomerate Breccia	cg bx
Precipitates, crystalline	Calcareous	pk	Travertine Limestone Dolomite	tv ls do
	Non-calcareous	pu	Gypsum Limonite Barite	gy li ba
Organic	Calcareous	ok	Mar	ma
	Carbonaceous	oc	Lignite Coal	lg co

TABLE 2.2. Igneous rock codes

	General	Code	Specific	Code
Intrusive	Acid (felsic)	ia	Syenite Granite Quartz Monzonite Granodiorite	sy gr qm gd
	Intermediate	ii	Quartz Diorite Diorite	qd di
	Basic (mafic)	ib	Quartz Gabbro Pyroxenite Dunite	qg gb py du
Extrusive	Acid (felsic)	ea	Trachyte Rhyolite Dacite	tr rh da
	Intermediate	ei	Andesite	an
	Basic (mafic)	eb	Quartz Basalt Basalt	qb bs
	Recent lava flow	la
	Pyroclastic	ep	Tuff Volcanic Breccia Agglomerate	tu vb ag

TABLE 2.3. Metamorphic rock codes

	General	Code	Specific	Code
Foliated	Fine grained	ff	Slate Phylite	sl ph
	Medium to coarse grained	fm	Schist Gneiss Granite Gneiss Diorite Gneiss	sc gn gg dg
	Coarse grained	fc	Migmatite	mi
Non-foliated	Fine grained	nf	Argillite Serpentinite	ar sp
	Medium to coarse grained	nm	Quartzite Hornfels Granulite	qt hf gl
	Coarse grained	nc	Amphibolite Hornblendite	am hb
	Calcareous	nk	Marble Dolomite Marble Serpentine Marble	mb dm sm

4. Coarse Fragment Lithology

Record up to three rock types in order of dominance from left to right on the form that make up the coarse fraction (i.e., gravels, cobbles, and stones) of the soil material. Characters are recorded using the same codes as outlined for bedrock type. If the lithologies are so mixed that dominance can not be determined, record by entering the code "mx."

5. Terrain Classification

Four information fields are provided for recording terrain texture, surficial material, surface expression and geomorphological process, respectively (Howes and Kenk 1997) (see Tables 2.4, 2.5, 2.6, and 2.7 and Figure 2.1). Up to three codes can be entered in each of these fields. Place qualifying descriptor codes (Table 2.8) in the appropriate field to the right of any other codes used in that field (superscript codes are no longer used). Code line 1 for the uppermost stratigraphic layer, and code line 2 for an underlying layer. For those wishing to use terrain subclasses and subtypes, refer to Howes and Kenk (1997).

TABLE 2.4. Terrain texture codes

Code	Name	Size (mm)	Other Characteristics
a	Blocks	> 256	Angular particles
b	Boulders	> 256	Rounded and subrounded particles
k	Cobble	64-256	Rounded and subrounded particles
p	Pebbles	2-64	Rounded and subrounded particles
s	Sand	0.062-2.000
z	Silt	0.002-0.062
c	Clay	< 0.002
d	Mixed fragments	> 2	Mix of rounded and angular fragments particles
g	Gravel	> 2	Mix of boulders, cobbles, and pebbles
x	Angular	> 2	Mix of blocks and rubble
r	Rubble	2-256	Angular particles
m	Mud	< 0.062	Mix of clay and silt
y	Shells	-	Shells or shell fragments
e	Fibric	-	Well-preserved fibre; (40%) identified after rubbing
u	Mesic	-	Intermediate composition between fibric and humic
h	Humic	-	Decomposed organic material; (10%) identified after rubbing

FIGURE 2.1. Relationship of size and roundness of the clastic textural terms.

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TABLE 2.5. Surficial (genetic) material codes

Code	Name	(Assumed Status)	Description
A	Anthropogenic	(A)	Artificial or human- modified material
C	Colluvium	(A)	Products of mass wastage
D	Weathered bedrock	(A)	In situ, decomposed bedrock
E	Eolian	(I)	Materials deposited by wind action
F	Fluvial	(I)	River deposits
FG	Glaciofluvial	(I)	Ice contact fluvial material
I	Ice	(A)	Permanent snow, glaciers, and icefields
L	Lacustrine	(I)	Lake sediments; includes wave deposits
LG	Glaciolacustrine	(I)	Ice contact lacustrine material
M	Morainal	(I)	Material deposited directly by glaciers
O	Organic	(A)	Accumulation/decay of vegetative matter
R	Bedrock	(-)	Outcrops/rocks covered by less than 10 cm of soil
U	Undifferentiated	(-)	Layered sequence; three materials or more
V	Volcanic	(I)	Unconsolidated pyroclastic sediments
W	Marine	(I)	Marine sediments; includes wave deposits
WG	Glaciomarine	(I)	Ice contact marine sediments

TABLE 2.6. Surface expression codes

Code	Name	Description
a	Moderate slope	Unidirectional surface; > 15∞ to < 26∞
b	Blanket	A mantle of unconsolidated materials; > 1 m thick
c	Cone(s)	A cone or segment of a cone; > 15∞
d	Depression(s)	A lower area surrounded by a higher terrain
f	Fan(s)	A segment of a cone; up to 15∞
h	Hummock(s)	Hillocks and hollows, irregular in plan; 15-35∞
j	Gentle slope	Unidirectional surface; > 3∞ and < 15∞
k	Moderately steep	Unidirectional surface; > 26∞ and < 35 slope
m	Rolling	Elongate hillocks; 3-15∞; parallel forms in plan view
p	Plain	Unidirectional surface; up to 3∞
r	Ridge(s)	Elongate hillocks; 15-35∞; parallel forms in plan view
s	Steep slope	Steep slopes; > 35∞
t	Terrace(s)	Step-like topography
u	Undulating	Hillocks and hollows; up to < 15∞; irregular in plan view
v	Veneer	Mantle of unconsolidated material; 0.1 to 1.0 m thick
w	Mantle of variable thickness	A layer or discontinuous layer of surficial variable thickness materials of variable thickness that fills or partially fills depressions in an irregular substrate. The thickness ranges from 0 to 3 m.
x	Thin veneer	A dominance of very thin surficial materials about 2-20 cm thick

TABLE 2.7. Geomorphological process codes

Code	Name	(Assumed Status)	Description
A	Avalanches	(A)	Terrain modified by snow avalanches
B	Braiding	(A)	Diverging/converging channels; unvegetated bars
C	Cryoturbation	(A)	Materials modified by frost heaving and churning
D	Deflation	(A)	Removal of sand and silt by wind action
E	Channeled	(I)	Channel formation by meltwater
F	Slow mass	(A)	Slow downslope movement of masses of cohesive or non-cohesive material
H	Kettle	(I)	Depressions in surficial material resulting from the melting of buried or partially buried glacier ice
I	Irregular	(A)	A single, clearly defined main channel channel displaying irregular turns and bends
J	Anastomosing	(A)	A channel zone where channels channel diverge and converge around many vegetated islands
K	Karst	(A)	Processes associated with the solution of carbonates
L	Surface	(A)	Zones of active seepage often found seepage along the base of slope positions
M	Meandering	(A)	Channels characterized by a regular channels pattern of bends with uniformed amplitude and wave length
N	Nivation	(A)	Erosion beneath and along the margin of snow patches
P	Piping	(A)	Subterranean erosion by flowing water
R	Rapid mass	(A)	Rapid downslope movement of dry, movement moist, or saturated debris
S	Solifluction	(A)	Slow downslope movement of saturated overburden across a frozen or otherwise impermeable substrate
U	Inundation	(A)	Seasonally under water because of high water table
V	Gully erosion	(A)	Parallel/subparallel ravines caused by running water
W	Washing	(A)	Modification by wave action
X	Permafrost	(A)	Processes controlled by the presence of permafrost
Z	Periglacial	(A)	Solifluction, cryoturbation, and processes nivation processes occurring within a single unit

TABLE 2.8. Qualifier codes

Code	Name	Description
A	Active	Used to qualify surficial material and geomorphological
I	Inactive	processes with regard to their current state of activity.

6. Soil Classification

The Canadian System of Soil Classification (Soil Classification Working Group, 1998) is tabulated alphabetically by soil order. Codes for great groups and subgroups are given in Appendix 2.1., Appendix 2.2 includes a key to soil orders. For those wishing to use family and phase criteria, refer to Soil Classification Working Group (1998) and include in "Notes."

7. Humus Form

Humus forms are classified to order and group according to Towards a Taxonomic Classification of Humus Forms (Green et al. 1993) Use Table 2.9 to enter codes. Appendix 2.3 contains a key to humus forms. For those wishing to use phases, refer to Green et.al. (1993), and include in "Notes."

TABLE 2.9. Codes for humus orders and groups

Order	Group	Code
MOR (R)	Hemimor Humimor Resimor Lignomor Hydromor Fibrimor Mesimor	HR UR RR LR YR FR MR
MODER (D)	Mormoder Leptomoder Mullmoder Lignomoder Hydromoder Saprimoder	RD TD MD LD YD SD
MULL (L)	Vermimull Rhizomull Hydromull	VL ZL YL

8. Hydrogeomorphic Units

The system defines broad hydrological processes which characterize landscape units and ecosystems by water sources and hydrodynamics. Element groups divide a system by patterns of waterflow which indicate generically hydrodynamics, water source, and connectivity in the landscape. Record the system code first and the element group code (where applicable) second (e.g., Fra= alluvial river). Subsystem codes are only presented for lacustrine, palustrine, and fluvial sites; those for other systems are under development. Use the codes in Tables 2.10 and 2.11.

TABLE 2.10. Codes for hydrogeomorphic systems

Code	System	Description
L	Lacustrine	Occurs adjacent to lakes and ponds and is directly affected by lacustrine processes (e.g., wave action, sedimentation, and relatively high nutrient content of flood waters).
P	Palustrine	Occurs in basins and depressions with poor drainage that collect water flows from runoff, groundwater, and precipitation. Often peatlands, ponds, and marshes.
F	Fluvial^a	Occurs along flowing water courses, the water course itself, and the surrounding (riparian) terrain and vegetation. Subject to flooding and sedimentation processes.
U	Upland	Occurs in sloping, level, and depressional sites not described by other hydrogeomorphic systems.
E	Estuarine	Consists of intertidal habitats where ocean water is at least occasionally diluted by freshwater runoff from the land. Occurs at the confluence of rivers and ocean and has characteristics that reflect the flooding and salinity gradients found there.
M	Marine	Exposed to waves and currents of the open ocean. Water regimes are determined primarily by the ebb and flow of oceanic tides.
^a Modifiers: r = river (20 m+ wide); s = stream (5-20 m); c = creek (1.5-5 m); v = rivulet (< 1.5 m).

TABLE 2.11. Codes for hydrogeomorphic subsystems

System	Element Group	Code	Description
Lacustrine or palustrine; confined basins	Closed basin	cb	Basin receives water from surrounding upland only, no inlet or outlet channel.
	Overflow basin	ob	Basin receives water from upland only; excess water flows through an outlet channel.
	Linked basin	lb	Basin receives water from upland and an inflow stream; excess water flows though an outflow. Includes basins with slow streams where there is little sedimentation or erosion.
	Terminal basin	tb	Basin receives water from upland and an inflow stream; no outlet channel.
Palustrine; unconfined slopes and hollows	Overflow hollow	oh	Hollow receives ground water from upslope; drains through outlet channel or watertrack.
	Linked hollow	lh	Hollow receives water from upland and an inflow stream; excess water flows out through an outflow stream or watertrack. Includes gullies with slow streams where there is little sedimentation or erosion.
	Blanket slope	bs	Occurs in subdued topography where basin types are not defineable.
	Toe slope	ts	Occurs on toe slope positions not confined by basin or hollow; water received from upslope, sheet or channelled flow
	Lobe slope	ls	Peatlands on slopes with a downslope edge elevated above the upland in the form of a lobe; water received from upslope, sheet or channelled flow.
Fluvial	Alluvial	a	Associated with low gradient streams where floodplain building processes predominate; flooding and subsequent deposition of alluvium leads to extensive floodplains of sandy or silty soils.
	Transport	t	Associated with moderate gradient streams where neither erosion or deposition forces predominate; floodplain development limited, in-stream bars and gravelly soil common.
	Headwater	h	Associated with high gradient streams where erosive processes predominate; flood plain and bar development limited; cobble, stone or bedrock substrates common

9. Rooting Depth

Rooting depth refers to the depth (cm) from the ground surface, which is the top of the uppermost soil horizon including organic horizons (e.g., Fm1), down to the bottom of the rooting zone (i.e., the level at which the majority of roots stop; for example, the end of "plentiful" and beginning of "few" rooting abundance).

10. Rooting Zone Particle Size

The particle size distribution within the mineral portion of the rooting zone is used to make broad interpretations. After determining rooting depth, estimate the rooting zone particle-size class as a weighted average of the mineral horizons within the rooting zone (Figure 2.2, Table 2.12). Where rooting is restricted to the organic horizons, use the organic material codes in Table 2.12. For the most part, class names and definitions have been modified from the Canadian System of Soil Classification family particle size criteria. Rooting zone classes are greatly simplified and use only percent coarse fragments (> 2 mm) by volume, and texture class sizes by percent weight for sand (.05 to < 2 mm), silt (< .05 to .002 mm), and clay (< .002). Two different classes can be entered on the data form if strongly contrasting size classes occur (e.g. CLS/FC= coarse-loamy over fine-clayey), however ranges of rooting zone particle-size classes can not be shown.

FIGURE 2.2. Rooting zone particle size classes.

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TABLE 2.12. Rooting zone particle size classes

Code	Class^a	Definitions
Coarse fragments > 70%:
F	Fragmental	Particles < 2 mm of various textures

Coarse fragments > 35 and less than 70%:
SS	Sandy-skeletal	Particles < 2 mm sandy
CLS	Coarse-loamy-skeletal	Particles < 2 mm coarse-loamy
FLS	Fine-loamy-skeletal	Particles < 2 mm fine-loamy
SIS	Silty-skeletal	Particles < 2 mm fine-silty or coarse-silty
CS	Clayey-skeletal	Particles < 2 mm clayey

Coarse fragments < 35 %
S	Sandy
CL	Coarse-loamy
FL	Fine-loamy
CSI	Coarse-silty
FSI	Fine-silty
FC	Fine-clayey
VFC	Very-fine-clayey

Organic Material Codes:
F	Fibric
M	Mesic
H	Humic
W	Woody
^a Refer to triangle in Figure 2.2 for proportion of sand and clay in the fine particle sizes (< 2 mm) of these classes.

11. Root Restricting Layer

If present, enter a code for the type of root restricting layer (Table 2.13), and the depth (cm) from the ground surface down to the top of the layer.

TABLE 2.13. Codes for root restricting layers

Code	Description
C	Strongly cemented horizon
P	Clay pan or restriction due to fines
K	Compacted morainal material
L	Lithic contact
W	Excessive moisture; this refers to the depth where the roots are being restricted by excessive moisture, but does not require the presence of free water at the time of sampling
X	Excessive accumulations of chemicals within the profile which inhibit root growth (i.e., CaCO3 )
Z	Permafrost; characterized by temperatures never exceeding 0∞C, ice cementation, ice lenses, or massive ice.
N	No root restriction evident.

12. Water Source

The most influential source of water on a site (determined by a qualitative assessment) is recorded using the codes in Table 2.14.

TABLE 2.14. Water source codes

Code	Water Source
P	Precipitation
G	Groundwater
S	Snowmelt (prolonged through the growing season)
F	Stream sub-irrigation and flooding
M	Mineral spring
T	Tidal, freshwater
E	Tidal, saltwater
Z	Permafrost

13. Seepage Water Depth

If seepage is present at the time of sampling, record the depth (cm) from the ground surface to the level of temporary or permanent subsurface water flow. Enter "NP" if not present.

14. Drainage Class and Soil Moisture Subclass

Drainage class describes the speed and extent to which water is removed from a mineral soil in relation to additions (Table 2.15.).

TABLE 2.15. Drainage classes and codes

Code	Class	Description
x	Very rapidly drained	Water is removed from the soil very rapidly in relation to supply. Water source is precipitation and available water storage capacity following precipitation is essentially nil. Soils are typically fragmental or skeletal, shallow, or both.
r	Rapidly drained	Water is removed from the soil rapidly in relation to supply. Excess water flows downward if underlying material is pervious. Subsurface flow may occur on steep gradients during heavy rainfall. Water source is precipitation. Soils are generally coarse textured.
w	Well drained	Water is removed from the soil readily, but not rapidly. Excess water flows downward readily into underlying pervious material or laterally as subsurface flow. Water source is precipitation. On slopes, subsurface flow may occur for short durations, but additions are equalled by losses. Soils are generally intermediate in texture and lack restricting layers.
m	Moderately well drained	Water is removed from the soil somewhat slowly in relation to supply because of imperviousness or lack of gradient. Precipitation is the dominant water source in medium- to fine- textured soils; precipitation and significant additions by subsurface flow are necessary in coarse-textured soils.
i	Imperfectly drained	Water is removed from the soil sufficiently slowly in relation to supply to keep the soil wet for a significant part of the growing season. Excess water moves slowly downward if precipitation is the major source. If subsurface water or groundwater (or both) is the main source, the flow rate may vary but the soil remains wet for a significant part of the growing season. Precipitation is the main source if available water storage capacity is high; contribution by subsurface or groundwater flow (or both) increases as available water storage capacity decreases. Soils generally have a wide range of texture, and some mottling is common.
p	Poorly drained	Water is removed so slowly in relation to supply that the soil remains wet for much of the time that it is not frozen. Excess water is evident in the soil for a large part of the time. Subsurface or groundwater flow (or both), in addition to precipitation, are the main water sources. A perched water table may be present. Soils are generally mottled and/or gleyed.
v	Very poorly drained	Water is removed from the soil so slowly that the water table remains at or near the surface for most of the time the soil is not frozen. Groundwater flow and subsurface flow are the major water sources. Precipitation is less important, except where there is a perched water table with precipitation exceeding evapotranspiration. Typically associated with wetlands. For organic wetlands, also evaluate the soil moisture subclass, and when entering on the form, separate from drainage by a slash. For example, v/ac.

Soil moisture subclasses (applied to organic soil order only) indicate the length of time the soil is saturated (Table 2.16). Record the subclass code in the "drainage" information field.

TABLE 2.16. Soil moisture subclasses and codes

Code	Moisture subclass	Description	Saturation period (mo.)	Moist period (mo.)
aq	Aqueous	Free surface water	11.5-12	< 0.5
pa	Peraquic	Soil saturated for very long periods	> 10	< 2
ac	Aquic	Soil saturated for moderately long periods	4-10	2-8
sa	Subaquic	Soil saturated for short periods	< 4	8-11.5
ph	Perhumid	No significant water deficits in growing season	< 2	8-11.5
hu	Humid	Very slight deficits in growing season	< 0.5	> 11.5

15. Flooding Regime

Flooding is defined as immersion of substrate by water (i.e., saturated peats not covered by surface water are not considered flooded). Flooding regimes may be indicated by one- or two-letter codes as appropriate for yearly frequency and seasonal duration (Table 2.17 and 2.18). A range of flooding regimes may also be entered (e.g., OB = occasional brief flooding and FT-AM = frequent temporary flooding to annual moderate flooding).

TABLE 2.17. Codes for frequency of flooding

Code	Description
A	Annual flood (at least once per year)
F	Frequent flooding (every 2-5 years)
O	Occasional flooding (> 5-year interval between flooding)
R	Rare flood (only during extreme events)
X	Never flooded

TABLE 2.18. Codes for duration and timing of flooding

Code	Description
W	Winter flooding
P	Permanent flooding during growing season
E	Extended flooding (exposed < 1 month during last part of growing season)
M	Moderate flooding (flooded for 1-3 months; exposed substrate for prolonged periods of the growing season)
T	Temporary flooding (7-30 days during the growing season)
B	Brief flooding (< 7 days during the growing season)
D	Diurnal flooding