Soils of the - Agriculture and Agri-Food Canada

DEAS SOILS (DS)
Location and Extent : Deas soils occur only on the lowlands of southeast Delta Municipality. There are abou t
100 ha of pure map units and 75 ha of Deas-Embree soil complex .
Topography and Elevation : The topography of Deas soils is gently undulating to undulating with slop e
gradients less than 3 percent . Land levelling has occurred in some areas . Elevations vary between 2 to 3 m
above sea level .
Parent Material and Texture : Deas soils have developed from medium to moderately fine textured, stone -
free Fraser River deltaic deposits composed of mixed marine and fresh-water sediments . Surface, subsurfac e
and subsoil textures are mainly silt loam with some variation to silty clay loam . At depths below about 75 to 10 0
cm, the textures usually change to sand or interbedded sand and silt . Below about 75 cm depth the deposit s
are generally saline and contain high amounts of sulphurous compounds .
Soil Moisture Characteristics : Deas soils are poorly drained . They are moderately pervious and have slo w
surface runoff and high water holding capacity . The watertable is near the surface during most of the winter bu t
gradually recedes during the growng season . Dykes provide protection from flooding during high tides . Sal t
water seepage through the underlying sandy strata causes saline conditions below about 75 to 100 cm .
General Soil Description : Deas soils have a black to very dark gray, friable, cultivated surface about 20 c m
thick which contains between 10 and 20 percent organic matter. The surface is underlain by about 50 cm of
grayish-brown to olive-gray, massive, silty material that is firm when moist, hard when dry and contain s
common, dark brown mottles . Below this is a massive, silty zone about 20 cm thick which contains common ,
pale yellow mottles and is high in sulphur compounds . The soil then gradually grades to dark gray, moderatel y
to strongly saline, fine sand or alternating lenses of sand and silt below 80 to 100 cm . Soil reaction is extremel y
acid throughout . Soil classification is Rego Humic Gleysol:saline phase .
Commonly Associated Soils : Embree, Sandel and Kitter soils are usually closely associated with Dea s
soils . Embree soils differ from Deas soils by containing an organic layer (10 to 30 cm thick) in the subsurface .
Sandel and Kitter soils differ by having grayer surfaces (usually containing less organic matter) . Kitter soils als o
differ by being moderately poorly rather than poorly drained and also are non-saline in the upper 100 cm .
Vegetation : All areas are cleared and cultivated . Rooting below about 50 cm is restricted by high watertabl e
conditions .
General Land Use Comments : (1) Deas soils are presently used for producing forage, cereal and othe r
field crops . With adequate artificial drainage and fertilization most climatically suited crops (except those ver y
susceptible to "wet-feet") can be grown . The saline subsoil conditions are usually sufficiently deep to have littl e
effect on most crops . (2) Deas soils are poorly suited for urban or similar uses . Soil bearing capacities ar e
variable, probably requiring special foundation construction . Basements and other excavations are impractica l
due to high watertables while unprotected underground utility installations are susceptible to corrosion due t o
saline subsoil conditions and the presence of substantial amounts of compounds high in sulphur . Hig h
watertables limit efficient operation of septic tank disposal fields . (3) Deas soils appear to be moderately suite d
for forest species such as Sitka spruce . Productivity for this species is estimated to be about 5 to 6 m 3/ha/yr.
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