Soils of the - Agriculture and Agri-Food Canada

ARNOLD SOILS . (AR)
Location and Extent : Arnold soils only occur in a few areas near Arnold Station in western Chilliwhac k
Municipality. There are about 150 ha of pure map units and 20 ha of Arnold-Henderson soil complex .
Topography and Elevation : Very gently sloping to undulating with slopes less than 5 percent is the usua l
topography of Arnold soils . They lie between 5 and 10 m above sea level .
Parent Material and Texture : Arnold soils have developed from moderately fine textured, stone-free Frase r
River floodplain deposits . These deposits, laid down by periodic flooding of the Fraser River, consist of thin ,
buried, dark-coloured, old surfaces alternating with thicker layers of lighter coloured materials . Surface ,
subsurface and subsoil textures vary from silt loam to silty clay loam to depths of at least 1 m .
Soil Moisture Characteristics : Arnold soils are moderately poorly drained . They are moderately perviou s
and have high water holding capacity and slow surface runoff . A fluctuating groundwater table is present nea r
the soil surface during prolonged, rainy periods and during the freshet stage of the Fraser River . It retreats t o
depths of 1 m or more during the latter parts of most growing seasons .
General Soil Description : Arnold soils have a dark grayish brown, cultivated, friable, silty surface about 2 0
cm thick, underlain by a grayish-brown, weakly structured, strongly mottled, silty layer between 15 mnd 30 c m
thick . Layers below this consist of black, 5 to 20 cm thick, buried, silty, old soil surfaces alternating with gray ,
moderately mottled, silty, 20 to 50 cm thick strata to a depth of at least 1 m . The mottles range from reddish t o
yellowish in colour. Soil reaction is medium acid to at least 1 m depth (1 :1 H20) . Soil classification is Orthic Humic
Gleysol.
Commonly Associated Soils : Henderson, Blackburn and Grigg soils occur in soil complexes with Arnol d
soils or in adjacent map polygons . Henderson soils differ from Arnold soils by having a deep, black, surfac e
layer (up to 80 cm thick) while Blackburn soils differ by being somewhat more poorly drained and clayey i n
texture . Grigg soils differ by having a well-defined clay accumulation layer in the subsoil .
Vegetation : Native vegetation has essentially all been cleared and the soils are used for a variety o f
agricultural crops . Rooting is partially restricted below about 70 cm depth by fluctuating groundwater tables .
General Land Use Comments : (1) Arnold soils are well suited for most agricultural crops . They are
presently used mostly for production of forages, peas, corn and other field crops . The periodically hig h
watertables restrict their use for perennial crops sensitive to saturated soils . Artificial drainage, where no t
already installed, is feasible and alleviates this problem . (2) Variable soil bearing capacities and periodic hig h
watertables are limiting for road and building construction . Septic tank operation is inefficient and excavation s
such as basements are impractical due to periodic high watertables . (3) Productivity of black cottonwood o n
Arnold soils is estimated to be between 12 and 15 m 3/ha/yr.
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