Soils of the - Agriculture and Agri-Food Canada

TRIGGS SOILS (TR)
Location and Extent : Triggs soils occupy substantial areas on the lowlands of the map area, mainly in Burn s
Bog, Glen Valley and in Richmond and Pitt Meadows Municipalities . Small, scattered areas also occur in uplan d
locations . About 3290 ha of pure map units and 480 ha of soil complexes are mapped . The complexes are
generally with Lumbum or Glen Valley soils .
Topography and Elevation : The topography of Triggs soils varies from nearly level or slightly depressiona l
to very gently sloping (domed) . Slope gradients are less than 2 percent and most areas lie at elevations les s
than 10 m above sea level .
Parent Material and Texture : Triggs soils have developed from deep (at least 2 m), undecompose d
organic deposits composed mainly of sphagnum and other mosses . Variable amounts of woody materia l
(trunks, branches, and roots) are also commonly present . The surface, subsurface and subsoil all consist of
relatively undecomposed (fibric) organic material . At depths below 150 cm or more, the organic materia l
sometimes becomes moderately decomposed . The underlying mineral deposits are usually medium o r
moderately fine textured Fraser River deltaic or floodplain sediments . In upland areas the mineral underlay i s
usually clayey glaciomarine sediments .
Soil Moisture Relationships : Triggs soils are very poorly drained . The watertable is at or near the surface
for most of the year except near the centre of some of the larger deposits where, because of their domed nature ,
the watertable may be somewhat lower . The soils are moderately pervious and have very high water holdin g
capacity and slow surface runoff . Some areas are partially drained by ditches at the present time .
General Soil Description : Triggs soils generally have a layer of living sphagnum moss on the soil surface .
This is underlain by about 20 cm of undecomposed (fibric), spongy and soft, yellowish-brown to yellowish-re d
organic material . Under this is 100 cm or more of very slightly decomposed (fibric), massive to weakly layered ,
slightly compacted, dark several thin, black bands of charcoal . The organic material consists mainly of mos s
remains . Gradual change then occurs to partially decomposed, dusky red to dark reddish brown organi c
material (fibric or mesic) usually composed of mixed moss, sedge, reed and grass remains . Soil reactions are
extremely acid throughout . Soil classification is Typic Fibrisol.
Commonly Associated Soils : Glen Valley, Lumbum, Gibson and Annacis soils often occur in clos e
association with Triggs soils . Glen Valley soils differ from Triggs soils by consisting of deep, undecomposed ,
organic deposits composed mainly of sedge and reed remains, rather than moss . Lumbum, Gibson an d
Annacis soils are also all organic but differ from Triggs soils in the following ways : Lumbum soils consist of deep ,
partially decomposed (mesic) organic materials ; Annacis soils are composed of deep, well-decompose d
(humic) organic deposits while Gibson soils are composed of 40 to 160 cm of partially decomposed organi c
material overlying silty or clayey Fraser River floodplain sediments .
Vegetation : The natural vegetation on Triggs soils is variable but is typical of poorly drained, extremely aci d
soil conditions . It includes birch, stunted lodgepole pine, hardhack, Labrador tea, blueberry, cranberry ,
bracken and sweetgale with sphagnum and other mosses on the ground surface . Rooting is restricted mainly to
the upper 30 cm .
General Land Use Comments : (1) Triggs soils are generally not suited for most agricultural crops unles s
extensive reclamation is undertaken . Blueberries and cranberries require relatively lesser amounts of reclama -
tion . Extensive drainage works are required as well as large amounts of lime and fertilizer to improve the acidi c
soil reactions and low fertility. Cultivation of the surface to accelerate surface decomposition is required t o
produce suitable seed beds . In several locations, Triggs soils are being mined for commercial peat . Th e
remaining, underlying partially decomposed organic material is also suitable for reclamation after the commercial
peat has been removed . (2) Triggs soils are unsuited for urban or related purposes . Very low soil bearing
strengths and high permanent watertables are the main limitations . The extremely acidic conditions may caus e
corrosion of unprotected concrete and other in-ground installations . (3) Triggs soils have very low fores t
productivity. Lodgepole pine is essentially the only coniferous species which grows on these soils .
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