Subordinate Horizon Suffixes (Soil Taxonomy)

Vocabulary flashcards covering all subordinate horizon suffixes used in soil profile descriptions.

a

Highly decomposed organic matter; contains less than 17 % rubbed fiber; used only with master horizon O.

b

Buried genetic horizon that shows evidence of past soil-forming processes.

c

Horizon with cemented concretions or nodules.

d

Physically restrictive layer caused by high bulk density (natural or human-induced compaction), e.g., dense basal till or plow pan.

e

Moderately decomposed organic matter; 17 % to <40 % rubbed fiber; used only with master horizon O.

f

Permafrost—permanently frozen layer that contains ice.

ff

Dry permafrost—permanently frozen layer not cemented by ice.

g

Strong gleying produced by saturation and anaerobic conditions; chroma of 2 or less.

h

Illuvial accumulation of amorphous, dispersible organic matter and aluminum-dominated sesquioxides coating sand and silt; used with master horizon B.

i

Slightly decomposed organic matter; more than 40 % rubbed fiber; used only with master horizon O.

j

Accumulation of jarosite (yellow iron hydroxy-sulfate mineral) typical of acid-sulfate soils.

jj

Evidence of cryoturbation in the active layer above permafrost (broken horizons, organic pockets, sorted rock fragments).

k

Visible pedogenic calcium carbonate accumulation (>50 % by volume) as filaments, masses, nodules, pendants, or disseminations.

m

Root-restrictive, pedogenically cemented horizon (>90 % cemented by CaCO₃, Fe, silica, gypsum, or other salts).

n

Accumulation of exchangeable sodium.

o

Residual accumulation of sesquioxides (iron and aluminum oxides).

p

Disturbance of the surface layer by plowing, trampling, traffic, etc.; used with master horizon A.

q

Accumulation of secondary silica as concretions, durinodes, or opal.

r

Weathered or soft bedrock; cemented but can be dug with hand tools; used with master horizon C.

s

Illuvial accumulation of amorphous, dispersible sesquioxides (Fe and Al) plus organic matter; used with master horizon B.

ss

Presence of slickensides formed by shear movement in shrinking-swelling clay soils.

t

Illuvial accumulation of clay indicated by clay films, bridges, or lamellae.

u

Presence of human-manufactured materials (artifacts such as bricks, metal, plastic, garbage).

v

Presence of plinthite—firm, iron-rich, humus-poor red concentrations that harden irreversibly with wet–dry cycles.

w

Weak color or structure or minimal pedogenic accumulation; used with master horizon B (not with transitional horizons).

x

Genetically developed horizon that is firm, brittle, and physically root-restrictive in part.

y

Accumulation of gypsum (or rarely anhydrite); <50 % by volume so other horizon features remain visible.

z

Accumulation of salts more soluble than gypsum, such as sodium chloride.