Soils of the - Agriculture and Agri-Food Canada

LEHMAN SOILS .
(LH)
Location and Extent : Lehman soils occupy small, scattered locations throughout the uplands of the map
area but are most common in the eastern half . About 130 ha of pure map units and 610 ha of soil complexe s
dominated by Lehman soils are mapped . The complexes are mostly with Coghlan, Judson, Defehr an d
Columbia soils .
Topography and Elevation : Lehman soils vary from level to very gently sloping or undulating and are ofte n
slightly depressional in relation to adjacent soils . The slopes are usually less than 4 percent and elevation s
range between 30 and 100 m above sea level .
Parent Material and Texture : Lehman soils have developed from coarse-textured glaciofluvial deposits
(and some fluvial deposits) which have up to 30 cm of medium-textured eolian material on, or mixed into, th e
surface . Surface textures are loam or silt loam while subsurface and subsoil textures are gravelly sand, sand o r
gravel, often stratified . Moderate amounts of stones are present in the surface where the eolian capping i s
shallow.
Soil Moisture Characteristics : Lehman soils are poorly drained . They are rapidly pervious and have low t o
moderate water holding capacity and slow surface runoff . They are subject to runoff and seepage from higher,
adjacent land and perched watertables develop above impermeable glacial till or glaciomarine sediment tha t
usually occurs at depth .
General Soil Description : Lehman soils (in uncleared areas) have up to 5 cm of raw to well-decomposed ,
mainly deciduous, organic forest litter on the mineral soil surface . Under this is about 15 cm of black or very dark
gray, weakly structured, friable, silty soil which, in turn, is underlain by an olive-gray or grayish-brown, friable ,
moderately structured, loamy to sandy layer about 10 cm thick containing common, strong brown to reddish -
brown mottles . This is abruptly underlain by at least 100 cm of stratified loose gravel or gravelly sand whic h
contains many, prominent, strong brown or reddish-brown mottles . Surface soil reaction is usually very strongl y
acid while subsurface and subsoil reactions vary from strongly to medium acid (1 :1 H 20) . Soil classification i s
Orthic Humic Gleysol .
Commonly Associated Soils : Coghlan, Defehr, Columbia and Judson soils often occur in close associa -
tion with Lehman soils . Coghlan and Defehr soils differ from Lehman soils by being imperfectly rather tha n
poorly drained . They also have reddish or brownish surfaces rather than the black surface of Lehman soils .
Also, Coghlan soils have strongly cemented subsurface layers . Columbia soils differ by being well-drained ,
while Judson soils consist of organic materials between 40 and 160 cm deep .
Vegetation : Many areas of Lehman soils are cleared and cultivated . The remaining natural vegetatio n
includes western red cedar, western hemlock, willow, red alder, black cottonwood and vine maple, understorie d
by cascara, salmonberry, skunk cabbage, ferns and others . Rooting depth is mainly restricted to the upper 50
cm by the periodic high watertables and gravelly subsoil textures .
General Land Use Comments : (1) Lehman soils are limited agriculturally by high watertables during th e
winter months and, in the summer after the perched watertables recede, by droughty conditions . Artificia l
drainage and irrigation are both required for good crop production . (2) High watertables during parts of the yea r
limit use of Lehman soils for urban or similar uses . Basements and other excavations can be expected t o
contain water during these periods and septic tank effluent disposal is severely restricted . Lehman soil areas
provide potential aggregate sources . Extraction should only occur during the drier parts of the year . (3) Lehma n
soils appear moderately suited for forest crops such as cottonwood . Potential annual wood production i s
estimated at between 9 and 12 m 3/ha .
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