Soils of the - Agriculture and Agri-Food Canada

ROSS SOILS (RS)
Location and Extent : Ross soils occur in small, scattered areas throughout the uplands of the report area .
About 370 ha of pure map units and 180 ha of soil complexes dominated by Ross soils are mapped ; th e
complexes are mostly with Lehman and Judson soils .
Topography and Elevation : Topographically, Ross soils vary from nearly level to gently sloping o r
undulating with slopes of less than 3 percent . They are usually depressional in relation to adjacent soils .
Elevations lie between 10 and 100 m above sea level .
Parent Material and Texture : The parent material of Ros s 'soils is medium and moderately fine textured ,
stone-free floodplain deposits of streams flowing over the uplands, these streams carry mainly sediment s
eroded from upstream glaciomarine, glacial till and eolian materials . Surface textures vary from silt loam to silty
clay loam ; the subsurface and upper subsoil is mainly silty clay loam or, sometimes, silty clay . At depths of 5 0
cm or more, gradation to sandy or gravelly textures often occurs .
Soil Moisture Characteristics : Ross soils are very poorly to poorly drained . They are moderately to slowl y
pervious and have high water holding capacity and slow surface runoff. The groundwater table is due to latera l
seepage from the adjacent streams, seepage from higher, adjoining soils and prolonged, heavy rainfall .
Flooding is common during periods of heavy rain .
General Soil Description : Ross soils generally have a dark gray to dark grayish brown, friable, cultivated ,
silty surface about 20 cm thick that sometimes contains a few reddish mottles . The surface is underlain by a
gray to dark grayish brown, weakly structured to massive, firm, silty to clayey zone about 30 cm thick tha t
contains common (or sometimes many), dark brown to reddish-brown mottles . This zone usually grades to 20
cm or more of dark gray to olive-gray, massive, clayey to silty material containing a few, brownish to reddis h
mottles . This zone is underlain (often abruptly) by loose, usually water saturated, sandy to gravelly material . Soi l
reactions grade from very strongly acid in the surface to slightly acid in the subsoil (1 :1 H 2O) . Soil classificatio n
is dominantly Rego Gleysol, changing to Rego Humic Gleysol in the few areas where the surface is darke r
coloured than usual .
Commonly Associated Soils : Sardis, Lehman and Judson soils are frequently closely associated wit h
Ross soils . Sardis soils differ from Ross soils by being gravelly and sandy in texture ; they are also well t o
imperfectly drained . Lehman soils have coarse-textured (gravelly) subsurfaces and subsoils and dark colore d
surfaces . Judson soils differ by consisting of 40 to 160 cm of organic material .
Vegetation : Most larger areas of Ross soils are cleared and cultivated . The remaining uncleared area s
support mostly deciduous species including willow, red alder, black cottonwood and some western red cedar
and western hemlock . Rooting is mainly restricted to the upper 40 to 50 cm by the high watertables and clayey
subsoil textures .
General Land Use Comments : (1) Ross soils usually occupy small, variably shaped areas which make s
them difficult to manage individually . They are limited for agricultural uses by high watertables and danger o f
flooding . Water control is required to improve them for a wier range of crops than is grown at present (mainl y
forages) . Access to Ross soils is sometimes difficult since they occur on the floors of steep-sided gullies an d
channels . (2) Poor drainage and flooding hazard limit Ross soils for urban and related uses . Flooding i s
common during and after heavy, prolonged rains while high watertables preclude basements and othe r
permanent excavations . Septic tank effluent disposal fields are severely impaired by high watertables and th e
usually dense, compact subsoil . (3) Black cottonwood is estimated to have the potential capability of producin g
12 to 15 m 3 /ha of wood/yr on Ross soils .
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