The Soils of The Regional Municipality of Ottawa=Carleton

Soil Landscape Units Four units were identified for the Oka
association. They are described as follows :
Recognized Recognized
Subgroups Series
01 : Dominantly rapidly Eluviated Munster
to well-drained soils Melanie
foundon very gently Brunisols
to gently sloping Orthic Melanie Oka
topography. Slopes Brunisols
range from 2 to 9% .
Parentmaterials have
been derived primarily
from limestone and
dolomite bedrock .
02 : Dominantly imper- Gleyed Eluviated
fectly drained soils Melanie Brunisols
found on levelto Gleyed Melanie
nearly level topo- Brunisols
graphy. Slopes range
from 0 to 2% . Parent
materials have been
derived primarily from
limestone and dolomite
bedrock .
03 : Dominantly well- Orthic Melanic
drained soils found Brunisols
on very gently to gently
sloping topography.
Slopes range from 2 to
9% . Parent materials
have been derived primarily
from gray-green
shale bedrock .
05 : Dominantly well Orthic Melanie
drained soils found Brunisols
onvery gently to gently
sloping topography.
Slopes range from 2 to
9% . Parentmaterials
have been derived primarily
from red shale
bedrock .
Taxonomic Components The Munster series (Eluviated
Melanie Brunisol subgroup) is well-drained and is composed of
materials mainly derived from limestone and dolomite
bedrock . The Ap horizon is dark brown with granular structure.
Ayellowish brown Ae or Aej horizon with granular structure
is present if it has not been incorporated into the surface
Ap horizon . A Btj or Bin horizon, or both, underly the eluviatedAhorizon.
Some illuviated clay is present on the granular
structured peds . The unweathered Ckhorizon generally occurs
within 50 cm depth and clay content is significantly lower than
inany ofthe weathered horizons occurring above it . Texture of
the fine earth fraction in the parent material or Ck horizon is
commonly loamy coarse sand or coarse sand, with loamy sand
and sand textures also occurring but less often. Texture of the
fine earth fraction in the upper horizons is slightly finer, having
larger proportions of medium sand . Surface textures are
most often sandy loam. The Ck horizon has single grain structure,
and color ranges from dark yellowishbrown to dark grayish
brown .
Some Munster profiles exhibit free carbonates in the
upper weathered horizons as well as the parent material . When
encountered, those horizons were designated with a k suffix
eg. Apk, Btjk etc .
The Oka series (Orthic Melanie Brunisol subgroup) is similar
to the Munster series in material origin . Profile characteristics
are also similar except for the absence of eluvial and
illuvial horizons . In their place a relatively thick brownto dark
brown Bm horizon is most often found .
The Gleyed Eluviated Melanic Brunisols and Gleyed
Melanic Brunisols composing the 02 soil landscape unit are
imperfectly drained and arethe gleyed equivalents ofthe better
drained series previously described . They are composed of
materials which have also been derived primarily from limestone
anddolomite bedrock . Profile characteristics of each are
similar to their better drained counterparts except for the presence
of distinct yellowish brown mottles within the upper 50
cm, and distinct to prominent mottles in the lower 50 cm of the
control section . Mottling within either profile is indicative of
periodic water saturation, including saturationperiods during
the growing season .
The well-drained OrthicMelanie Brunisols composing the
03 soil landscape unit consist of materials which have primarily
been derived from gray-green shale bedrock . Flat angular
pieces of noncalcareous gray shale make up a significant proportion
of the material, and in some deposits account for
nearly all of the coarse fragments within the profile. Varying
amounts of calcareous material also occur within the profile.
Due to the shale dominance, these soils are less calcareous than
the Oka series and at times are noncalcareous . Soil reaction,
although highly variable, also tends to be lower than the Oka
series .
The well-drained Orthic Melanic Brunisols of the 05 soil
landscape unit comprise materials which have been derived
primarily from red shale bedrock . The dominance of noncal
careous soft red shale fragments in the profile distinguishes
these soils fromothers in the association .
Mapped Soil Combinations More than 50% of all Oka soils
were mapped in combination with soils of other associations .
Approximately 1,400 ha were mapped in combinations in
which they were the dominant component, and 1,600 ha were
mapped in combinations in which they were the significant
component . Oka-Farmington and Farmington-Oka combinations
were by far the most frequent and extensive . Approximately
1,800 ha of Oka soils occur in those combinations in
almost equal proportions . Much less extensive but significant
amounts of Oka soils were also mapped with soils of the Jockvale
andKars associations .
General Land Use Oka soils at best are of marginal agricultural
capability for common field crops . Hay production
occurs where surface stoniness is not too severe, but the main
agricultural use found on Oka soils is that of permanent pasture.
Some Oka beach deposits are being economically mined
for aggregate in areas wherethe materials arethick enough and
well sorted . Significant areas of Oka soils also occur as abandoned
farmland or remain under forest vegetation .
Correlation to Ottawa Urban Fringe Calcareous Oka soils in
the survey area constituted primarily of limestone or dolomite
coarse fragments are similar to those found in the Ottawa
Urban Fringe. In both surveys these soils represent the vast
majority of soils included in the association . Due to the frequent
occurrence of shaley beach materials in the survey area,
however, additional landscape units for those soils were developed
which do not occur in the Urban Fringe survey. It was
decided that the limited occurrence and similar mode ofdeposition
of those soils justified a broadening of the association
concept .