Soils of the - Agriculture and Agri-Food Canada

SU MAS SOILS
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Location and Extent :
Sumas soils occur only in the eastern part of the map area . west of the Vedder Can a
and occupy mainly the basin of former Sumas Lake (the lake was drained in the 1920`s) . About 2400 ha e' r
map units and 270 ha of Sumas-Dixon :shallow variant soil complex are mapped .
topography and Elevation : The topography of Sumas soils is nearly level with some variation to gent'' ,
undulating Slope gradients are less than 2 percent and elevations are below 5 m above sea level .
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Parent Material and Texture :
The parent material of Sumas soils is coarse-textured lacustrine deposit s
rface textures are usually loamy sand with some variation to sandy loam . Subss, aCe and subsoil ire s
dium or coarse sand . occasionally containing bands of loamy sand
Soil Moisture Characteristics :
Sumas soils are poorly to very poorly drained . They are rapidly perv c _
have low water holding capacity and slow surface runoff . Most of the Sumas soil areas have controlled war s
s achieved through a system of ditches . floodgates and pumping . Sub-irrigation of most of the are a
mplished by manipulation of water levels in drainage ditches During the winter especially, temporar y
ing may occur during heavy rains which rapidly raise the already high groundwater table .
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General Soil Description : Sumas soils have a sandy, cultivated surface about 15 to 20 cm thick, which is ,
dark grayish brown, friable and contains sometimes, faint reddish or brownish mottles . The surface is unde r
by about 30 cm of very friable to loose . grayish-brown to olive-gray, medium sand containing few to comma '
usually faint mottles along old root channels . This zone, in turn, grades to loose, olive-gray, medium or coars e
sand . usually water saturated and containing occasional, variably coloured mottles . Soil reaction gere n a . 1 i
grades from strongly or eery strongly acid irl the surface to slightly acid or neutral in the subsoil (1 1 H-n) S
classification is Rego Gleysol .
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Commonly Associated Soils : Dixon soils are often found near the margin of Sumas soils They are poorl y
drained as are Sumas soils but have s i lty to o ayes __ : rface and subsurface textures which
sandy textures of Sumas soil s
east with +h F
1 I Vegetation : Essentially all areas of Sumas soils are cleared and cultivated . A few, isolated uncleared area s
support grasses, sedges, reeds, willow and black cottonwood Hooting is generally restricted to the upper 5 0
cm by the high groundwater level s
to 38 Landscape across the nearly
level, poorly drained sandy Sumas soils .
These soils are used for a variety of annua l
cash crops . Note the level of the water in the
ditch. Subirrigatlon during the growing sea -
son is provided by controlling the water levels
in the ditches .
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