Soils of the - Agriculture and Agri-Food Canada

GUICHON SOILS (GU)
Location and Extent : Guichon soils occur only in south Delta Municipality, west of the Boundary Bay Airport .
There are 370 ha of pure map units and 95 ha of soil complexes dominated by Guichon soils . The complexes
mainly are with Spetifore and Ladner soils .
Topography and Elevation : Guichon soils are nearly level to very gently undulating with slopes less than 2
percent. They all lie less than 3 m above sea level .
Parent Material and Texture : Guichon soils have developed from medium to moderately fine texture d
deltaic deposits, 30 to 80 cm thick, which overlie moderately-coarse textured sediments . Surface and subsurface
textures are silty clay loam or silt loam . The subsoil is loamy sand or sandy loam, frequently containing thin ,
silty lenses . The subsurface and subsoil are strongly saline and usually high in sulphur compounds .
Soil Moisture Characteristics : Guichon soils are poorly drained . They are moderately pervious and have
slow surface runoff and moderate water holding capacity. The watertable is at or near the surface during th e
winter and surface ponding commonly occurs during heavy rain . The sandy subsoil is subject to salt-wate r
seepage from nearby Boundary Bay .
General Soil Description : Guichon soils have a black or very dark gray, friable, silty, cultivated surface ,
about 20 cm thick, which becomes hard when dry. It is underlain by about 30 cm of strongly blocky or prismatic ,
gray or olive-gray, very firm, silty to clayey material which contains common to many, yellowish-red to yellowish -
brown mottles and some clay films on ped surfaces. This is underlain or grades to olive-gray, massive, sand y
material which contains a few, strong brown mottles . Ditch faces and other exposures frquently have precipi -
tated salts below about 20 cm depth . Soil reactions are very strongly or strongly acid in the surface an d
subsurface and grade to slightly acid in subsoil. Soil classification is Orthic Humic Gleysol:saline phase.
Commonly Associated Soils : Ladner, Benson, Mathews and Spetifore soils are usually closely associate d
with Guichon soils . Ladner soils differ from Guichon by consisting of 1 m or more of silty to clayey soil befor e
encountering the subsoil sands . They also have a well defined clay accumulation layer in the subsurface .
Benson and Mathews soils differ by being dominantly sandy in texture ; as well, Mathews soils are non-saline .
Spetifore soils differ by consisting of deep, silty materials .
Vegetation : All Guichon soil areas are cleared and cultivated . Salt tolerant species tend to invade pasture s
and other perennial crops . Rooting is mostly restricted to the upper 50 cm by saline subsoil conditions and hig h
watertables .
General Land Use Comments : (1) Guichon soils are mainly used for forage production although fiel d
crops such as oats and canning peas are also grown . Rooting depth and water penetration can be improved b y
subsoiling, especially coupled with underdrainage or other watertable control . Irrigation is required for goo d
crop production during dry summers and also assists in leaching the soil of excess salts . (2) Generally low soi l
bearing strengths may cause subsidence problems if heavy structures are erected and excavations will usuall y
contain water, especially during the winter. Unprotected buried utilities and similar installations are likely t o
suffer from severe corrosion . Septic tank effluent disposal is severely impaired by the high watertables .
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