Soils of the - Agriculture and Agri-Food Canada

KEYSTONE SOILS . (KE)
Location and Extent : Keystone soils occur north of the Fraser River, mainly in the western parts of Missio n
and eastern parts of Maple Ridge Municipalities . There are 430 ha of pure map units and 1040 ha of soi l
complexes dominated by Keystone soils . Most complexes are with Stave soils ; a few areas are complexes wit h
Roach, Errock or Whatcom soils .
Topography and Elevation : The topography of Keystone soils is mostly gently to moderately sloping o r
undulating to gently rolling with slopes between 3 and 10 percent . A few, very steeply sloping areas alon g
gullies and escarpments also occur ; here the slopes may rise to over 50 percent . Keystone soils generally li e
between 30 and 150 m above sea level .
Parent Material and Texture : Keystone soils have developed from coarse-textured glaciofluvial deposit s
with variable amounts of silty eolian material mixed into the upper 25 cm . Surface textures vary from sandy loa m
to silt loam, although loam is most common . Subsurface and subsoil textures are gravelly sand or gravel . Th e
surfaces are moderately stony and the lower subsoil is strongly cemented to indurated . Usually there are
moderate to many, fine, hard concretions in the surface .
Soil Moisture Characteristics : Keystone soils are dominantly well drained, varying to moderately wel l
drained in a few areas where the subsoil cementation is shallow. They are rapidly pervious and have low wate r
holding capacity and slow surface runoff . Slight restrictions to downward water movement is caused by th e
cementation in the subsoil .
General Soil Description : Keystone soils usually have 5 to 10 cm of variably decomposed, organic fores t
litter on the soil surface . This overlies 2 to 5 cm of friable, grayish, leached loamy material which is underlain b y
about 20 cm of dark reddish brown or reddish-brown, friable, loamy soil . Under this is about 50 cm of loose
gravel or gravelly sand containing few to common, distinct mottles in the lower part . Abruptly underlying this a t
about 80 cm depth is 20 to 40 cm of hard, massive, strongly cemented, variably colored gravel or gravelly san d
containing many, prominent, yellowish or reddish mottles . A distinct root accumulation zone (root mat) up to 5
cm thick is frequently present above the cementation . Soil reaction grades from extremely acid in the organi c
surface horizons to strongly acid in the subsoil . Soil classification is Duric Humo-Ferric Podzol .
Commonly Associated Soils : Stave, Roach and Errock soils are often closely associated with Keyston e
soils . Roach and Errock soils lack the loamy surface layer (are gravelly to the surface) and the cemented layer s
begin in the subsurface . Additionally, Errock soils are imperfectly drained . Stave soils differ by being mainl y
sandy rather than gravelly in the subsurface and subsoils . Also, compact glacial till or glaciomarine deposits
occur within 1 to 2 m of the soil surface .
Vegetation : Some areas of Keystone soils are cleared and cultivated, mainly for forage or pasture . Uncleared
areas mostly support a variable, second-growth forest consisting of, among others, coast Douglas-fir, wester n
hemlock, western red cedar and red alder. Rooting to about 80 cm is unrestricted but is severely limited below
that by strong soil cementation . Appreciable root concentrations (root mats) often occur immediately above th e
cementation .
General Land Use Comments : (1) Keystone soils are moderately suited for agricultural cropping .
Moderately stony surfaces, sometimes adverse topography and low water holding capacity are the mai n
limitations . If stones are cleared and irrigation is available, most crops can be successfully grown . (2) Keyston e
soils are well suited for urban uses . They are well-drained, have high bearing capacity and the topography i s
usually suitable . Septic tank effluent fields should function well if installed below the cemented subsoil layer . A
potential for groundwater contamination exists however, due to incomplete filtration by the coarse-texture d
subsoil material . Potential aggregate sources are available in Keystone soil areas . (3) Keystone soils are
moderately to well suited for forest growth although some growth limitations are imposed by droughty conditions
during dry summers . Data from a limited number of plots indicates potential annual wood growth b y
Douglas-fir to be between 9 and 12 m 3/ha .
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