Soils of the - Agriculture and Agri-Food Canada

NIVEN SOILS (NN)
Location and Extent : Niven soils occupy small, scattered areas on the Fraser River floodplain, usually nea r
the boundary between organic and mineral soils . About 160 ha of pure map units and 85 ha of soil complexes
dominated by Niven soils are mapped . The complexes are usually with Hallert, Hjorth or Annis soils .
Topography and Elevation : Niven soils are nearly level to gently undulating with slopes less than 2 percen t
and often are slightly depressional in relation to adjacent soils . Elevations lie less than 10 m above sea level .
Parent Material and Texture : Niven soils have developed from moderately fine to medium-textured Frase r
River floodplain deposits, usually 30 to 80cm thick, which overlie variably decomposed, organic materials .
Surface and subsurface textures are silty clay loam or silt loam . The textures of the upper subsoil, where th e
mineral deposits are sufficiently thick, are similar . Generally, however, the subsoil is variably decompose d
organic material, often containing thin, silty bands .
Soil Moisture Characteristics : The drainage of Niven soils is poor to very poor. They are moderatel y
pervious and have high water holding capacity and slow surface runoff . The groundwater table is near, an d
sometimes at, the soil surface for most of the winter although it recedes somewhat during the growing season .
Surface ponding is common after heavy, prolonged rains .
General Soil Description : Niven soils generally have a dark gray to gray, silty, cultivated surface layer ,
about 15 cm thick, which is friable to firm and moderately subangular blocky structured . It is underlain by about
30 cm of massive, gray, very firm, silty to clayey material containing common, dark brown to reddish-brow n
mottles . This then grades to about 15 cm of alternating thin bands of gray, massive, silty material and very dar k
brown, partially to well-decomposed organic material . Under this is 50 cm or more of mainly dark brown ,
massive, peat or muck which usually contains some silt, either disseminated through the organic material o r
occurring as occasional, thin, gray bands . Soil reaction varies from strongly to very strongly acid in the surfac e
to medium or strongly acid in the subsoil (1 :1 H 20) . Soil classification is Rego Gleysol.
Commonly Associated Soils : Hallert, Hjorth, Annis and Hazelwood soils are often closely associated wit h
Niven soils . Hallert soils differ from Niven soils by consisting of alternating organic and silty mineral bands to 1 m
or more . Hjorth, Annis and Hazelwood soils all lack the subsoil organic material that is present in Niven soils .
Additionally, Hjorth soils differ by being silty throughout, while Annis soils have an organic surface layer an d
Hazelwood soils are clayey.
Vegetation : Most areas of Niven soils are cleared and cultivated . Uncleared areas support a variety of
moisture tolerant species including western red cedar, willow, vine maple, red alder, skunk cabbage, sedge s
and reeds . Rooting depth is mainly restricted to the upper 50 cm by the high, prolonged groundwater tables .
General Land Use Comments : (1) The main agricultural limitation of Niven soils is poor drainage . Mos t
perennial crops suffer substantially during the winter months while cultivation and planting is retarded durin g
the spring . Artificial drainage is required for adequate watertable control . The watertable, however, should not
be lowered more than necessary for good crop growth in order to avoid undue subsidence of the underlyin g
organic material . (2) Urban and similar uses are not suited to Niven soils . Soil bearing strengths are low, hig h
watertables preclude basements and other excavations, periodic surface flooding is probable and septic tan k
effluent disposal fields are severely inhibited by high groundwater levels .
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