Soils of the - Agriculture and Agri-Food Canada

ERROCK SOILS (ER)
Location and Extent : Errock soils are relatively uncommon and occur mainly in the vicinity of Steelhead .
There are 30 ha of pure map units and 80 ha of Errock-Roach soil complex .
Topography and Elevation : The topography of Errock soils is level to gently undulating with slopes les s
than 5 percent . The soils are usually slightly depressional in relation to adjacent soils and lie at elevations abou t
730 m above sea level .
Parent Material and Texture : Errock soils have developed from coarse-textured, gravelly and stony
glaciofluvial deposits . Surface textures are usually loamy sand or sandy loam, sometimes gravelly, whil e
subsurfaces and subsoils are gravelly sand or sandy gravel . The soils are very to excessively stony an d
subsurface layers are strongly cemented to indurated .
Soil Moisture Characteristics : Errock soils are imperfectly drained . They are rapidly pervious and have
slow surface runoff and low water holding capacity . Downward water movement is slightly impeded by th e
subsurface cemented layers and temporary, perched watertables develop above this zone during periods o f
heavy, prolonged precipitation . The soils are subject to runoff and seepage from adjacent, higher areas .
General Soil Description : Errock soils generally have between 10 and 20 cm of coniferous forest litter o n
the mineral soil surface, the lower half of which is well-decomposed . The organic material is underlain by 5 to 1 0
cm of gray, strongly leached, sandy material which, in turn, is underlain by about 15 cm of friable, dark reddis h
brown, sandy and gravelly material containing about 10 to 20 percent organic matter . This layer is abruptl y
underlain by an extremely firm, very strongly cemented, gravelly and stony zone, about 40 cm thick, whic h
varies in colour from yellowish-brown to strong brown and contains common, reddish mottles . Below about 60
cm gradual change to loose, stony gravel or gravelly sand begins . Soil reaction varies from extremely acid in th e
upper part to strongly acid in the subsoil . Soil classification is Gleyed Ortstein Ferro-Humic Podzol .
Commonly Associated Soils : Roach soils commonly occur in close association with Errock soils . They are
similar to Errock soils except for being well, rather than imperfectly, drained . They tend to occupy slightly highe r
topographic landscape positions than do Errock soils .
Vegetation : Coast Douglas-fir, western red cedar and western hemlock are the dominant tree cover . Rootin g
is mainly restricted to the upper 30 cm by the cemented subsurface layer and coarse, stony textures .
General Land Use Comments : (1) Errock soils are generally poorly suited for agricultural use because o f
excessive stoniness, low fertility, shallow rooting depth and low water holding capacity. Any arable agricultura l
use will require substantial irrigation, stone-clearing and fertilization for satisfactory production . (2) Errock soil s
have high bearing strength for urban types of construction although stony, cemented soil conditions make
excavations for basements and underground utilities difficult . Septic tank effluent disposal fields shoul d
operate efficiently (if installed below the cemented zone), however, potential groundwater contamination i s
possible because of poor filtration by the coarse subsoils . Errock soils have potential as aggregate sources . (3 )
Limited plot data indicates Errock soils produce good growth of western hemlock and Douglas-fir, about 9 to 1 2
m3 of wood/ha/yr. The low soil water holding capacities seem to be offset by the restricted drainage .
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