Soils of the - Agriculture and Agri-Food Canada

SECRECY SOILS (SL)
Location and Extent : Sechelt soils occur only in the vicinity of Sechelt on the Sunshine Coast where abou t
1670 ha of pure map units and 85 ha of Sechelt-Dean soil complex are mapped .
Topography and Elevation : The topography of Sechelt soils varies from gently to steeply sloping wit h
slope gradients between 5 and 30 percent . Elevations range from sea level to about 400 m above sea level .
Parent Material and Texture : Sechelt soils have developed from deep, coarse-textured (sandy), mainl y
stone-free alluvial fan and delta deposits which change sometimes to gravel below 2 m or more . Surfac e
textures vary from sand to loamy sand . Subsurface and subsoil textures are mainly medium or coarse san d
containing, sometimes, thin strata of gravelly material .
Soil Moisture Relationships : Sechelt soils are rapidly to well drained . They are rapidly pervious and have
low water holding capacity and slow surface runoff .
General Soil Description : Sechelt soils have a variably decomposed layer of organic forest litter less tha n
10 cm thick on the soil surface . The organic material is underlain by a discontinuous, gray, loose, strongl y
leached, sandy layer less than 5 cm thick . It in turn, is abruptly underlain by about 20 cm of reddish-brown ,
loose, sandy material . This grades to about 50 cm of mainly loose, yellowish-brown, sandy material tha t
sometimes contains thin, reddish, weakly cemented, gravelly lenses . Below this is deep, loose, variabl y
coloured sand . Soil reactions range from very strongly acid in the upper soil to medium or strongly acid in the
lower subsoil . Soil classification is mostly Orthic Humo-Ferric Podzol although some Eluviated Dystric Bruniso l
areas are also included, particularly at the lower elevations .
Commonly Associated Soils : Dean, Capilano and Bose soils are commonly associated with Sechelt soils .
Dean and Capilano soils differ from Sechelt soils by being gravelly in texture . Additionally, Capilano soils hav e
strongly cemented subsurface layers . Bose soils also have gravelly and stony surface and subsurface layer s
but compact, loamy glacial till or clayey glaciomarine deposits occur in the subsoil .
Vegetation : Small areas of Sechelt soils are cleared, mainly for forage or pasture production or are used a s
urban sites . Uncleared areas support a variable forest consisting mainly of coast Douglas-fir, red alder an d
some western red cedar and lodgepole pine ; some Sitka spruce also occurs at the lower elevations near th e
sea shore . Rooting is unrestricted to at least 100 cm depth .
General Land Use Comments : (1) Low soil water holding capacity resulting in droughtiness is the mai n
agricultural limitation of Sechelt soils . In some locations adverse topography is also limiting . Adequate irrigatio n
and fertilization will make Sechelt soils productive for a variety of agricultural crops . (2) Where topography is no t
excessive, Sechelt soils are suited for urban uses . Basements and other excavations are easy to construct, an d
septic tank effluent disposal fields should function efficiently due to the rapid soil permeability. High con -
centrations of septic tank fields in small areas may, however, lead to potential groundwater contaminatio n
because of incomplete filtration by the coarse textured soil materials . Sechelt soil areas are also sources o f
aggregate, mainly sand . (3) Forest growth is moderate, limited mainly by soil moisture deficiencies during the
growing season . Estimated annual wood production by Douglas-fir is about 6 .5 to 8 m3/ha .
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