LOCATION LAURENTZEN IDEstablished Series
The Laurentzen series consists of deep and very deep, well drained
soils that formed in alluvium. Laurentzen soils are on fan terraces or
basalt plains and have slopes of 0 to 30 percent. Permeability is
moderately slow. The average annual precipitation is about 14 inches,
and the average annual air temperature is about 41 degrees F.
TAXONOMIC CLASS: Fine-silty, mixed, superactive, frigid Pachic Ultic Argixerolls
TYPICAL PEDON: Laurentzen loam in rangeland. (Colors are for dry soil
unless otherwise noted).
A1--0 to 7 inches; brown (7.5YR 5/2) loam, dark brown (7.5YR 3/2)
moist; weak medium platy structure parting to weak fine granular; soft,
friable, slightly sticky and slightly plastic; many very fine and fine
roots; many very fine interstitial pores; slightly acid (pH 6.4); clear
smooth boundary. (2 to 8 inches thick)
A2--7 to 14 inches; brown (7.5YR 5/2) loam, dark brown (7.5YR 3/2)
moist; weak medium subangular blocky structure parting to weak fine
granular; slightly hard, friable, slightly sticky and slightly plastic;
many very fine and fine roots; common fine and medium tubular pores;
neutral (pH 6.6); clear wavy boundary. (6 to 17 inches thick)
Bt1--14 to 23 inches; brown (7.5YR 5/2) light clay loam, dark brown
(7.5YR 3/2) moist; weak medium and coarse prismatic structure parting
to moderate medium and coarse subangular blocky; hard, firm, sticky and
plastic; many very fine and fine roots; many fine and medium tubular
pores; thin nearly continuous clay films on faces of peds and in pores;
neutral (pH 6.6); clear wavy boundary. (4 to 10 inches thick)
Bt2--23 to 30 inches; brown (7.5YR 5/2) clay loam, dark reddish
brown (5YR 3/4) moist; weak medium prismatic structure parting to
moderate medium subangular blocky; hard, firm, sticky and plastic; many
very fine and fine roots; many fine and medium tubular pores; thin
continuous clay films on faces of peds and in pores; many 1 to 2 cm.
krotovinas; neutral (pH 6.6); clear irregular boundary. (5 to 11
inches thick)
Bt3--30 to 42 inches; brown (7.5YR 5/4) clay loam, dark reddish
brown (5YR 3/4) moist; moderate fine and medium subangular blocky
structure; slightly hard, friable, sticky and plastic; many very fine
and fine roots; many fine and medium tubular pores; thin continuous
clay films on faces of peds and in pores; neutral (pH 6.6); clear wavy
boundary. (10 to 16 inches thick)
Bt4--42 to 60 inches; brown (7.5YR 5/4) cobbly clay loam, dark
reddish brown (5YR 3/4) moist; moderate fine and medium subangular
blocky structure; slightly hard, very friable, sticky and plastic; few
fine roots; many fine and medium pores; thin patchy clay films on
horizontal and vertical faces of peds; 15 percent basalt cobbles and 20
percent pebbles; neutral (pH 6.8).
TYPE LOCATION: Camas County, Idaho; about 2.5 miles north and 2 miles
west of Hill City; 1,400 feet east and 2,300 feet south of the
northwest corner of sec. 18, T. 1 S., R. 12 E.
RANGE IN CHARACTERISTICS:
Depth to bedrock - 40 to 72 inches
Average annual soil temperature - 42 to 46 degrees F.
Thickness of mollic epipedon - 20 to 35 inches
Base saturation - 50 to 75 percent in upper 75 cm
Reaction - slightly acid or neutral
A horizon
Hue- 10YR or 7.5YR
Value- 4 or 5 dry, 2 or 3 moist
Clay content - 18 to 27 percent
Bt horizons
Hue- 10YR through 5YR
Value- 4 or 5 dry, 3 or 4 moist
Chroma- 2 through 4 dry or moist
Texture - CL, SICL, L
Clay content - 22 to 35 percent
Sand- contains less than 15 percent sand coarser than very fine sand
COMPETING SERIES: There are no other series in this family. The
similar Brinegar series is fine-loamy and moderately well drained.
GEOGRAPHIC SETTING: Laurentzen soils are on fan terraces or basalt
plains and have slopes of 0 to 30 percent. The soils formed in
alluvium. Elevations are 4,800 to 6,000 feet. The soils have warm dry
summers and cold moist winters. The average annual precipitation is 12
to 16 inches, most of which comes as early spring rain and winter
snow. The average annual air temperature is 40 to 44 degrees F. The
frost-free period is 60 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gaib, Harahill, Manard,
Polecreek, and Magic soils. Gaib and Polecreek soils are 10 to 20
inches deep to bedrock. Manard, Harahill, and Magic are 20 to 40
inches deep. Harahill soils have fine-loamy control sections and lack
argillic horizons. Manard soils have a clayey control section.
Polecreek are clayey-skeletal and Magic soils are clayey throughout.
Gaib soils are on foothills and mountainsides. Harahill, Manard,
Polecreek, and Magic are on similar landscapes as the Laurentzen soil.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff;
moderately slow permeability.
USE AND VEGETATION: Used mainly for rangeland, small areas used for
non-irrigated cropland. Vegetation is bluebunch wheatgrass, Idaho
fescue, mountain big sagebrush, and antelope bitterbrush.
DISTRIBUTION AND EXTENT: Basalt plains in the higher elevations of
southwest and southcentral Idaho. The series is of limited extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Camas County, Idaho, 1977.
REMARKS: Diagnostic horizons and features recognized in this series
are:
Mollic epipedon - occurs from the soil surface to approximately 23
inches (A1, A2, and Bt1 horizons)
Argillic horizon - the zone from 14 to 34 inches (Bt1, Bt2, and Bt3
horizons)
National Cooperative Soil Survey