LOCATION FROHMAN OR
Established Series
Rev. BBL/JSP/RWL
05/2013
FROHMAN SERIES
The Frohman series consists of shallow to duripan, well drained soils that formed in silty lacustrine material and very gravelly alluvium of mixed origin. Frohman soils are on terraces. Slopes are 0 to 20 percent. The mean annual precipitation is about 10 inches and the mean annual temperature is about 52 degrees F.
TAXONOMIC CLASS: Loamy, mixed, superactive, mesic, shallow Xeric Haplodurids
TYPICAL PEDON: Frohman silt loam, cultivated. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 8 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; weak medium platy structure parting to weak fine subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine and fine pores; slightly alkaline (pH 7.6); abrupt smooth boundary. (7 to 10 inches thick)
Bw--8 to 12 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; moderate medium prismatic structure; hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many fine and very fine pores; moderately alkaline (pH 8.2); abrupt smooth boundary. (3 to 10 inches thick)
Bqm--12 to 18 inches; pale brown (10YR 6/3) indurated duripan of silt loam material, dark brown (10YR 3/3) moist; massive; extremely hard, extremely firm; gray (10YR 6/1) thin laminar capping on surface of duripan; root mat on surface; many very fine pores; moderately alkaline (pH 8.2); abrupt smooth boundary. (3 to 10 inches thick)
C1--18 to 28 inches; light gray (10YR 7/2) silt loam, brown (10YR 5/3) moist; massive; hard, friable, nonsticky and nonplastic; few very fine pores; moderately alkaline (pH 8.4); clear wavy boundary. (0 to 14 inches thick)
C2--28 to 36 inches; light gray (10YR 7/2) silt loam, pale brown (10YR 6/3) moist; massive; hard, friable, nonsticky and nonplastic; few very fine pores; strongly calcareous; moderately alkaline (pH 8.4); abrupt smooth boundary. (0 to 8 inches thick)
2Bkqm--36 to 42 inches; very gravelly indurated duripan; massive; extremely hard, extremely firm; pebbles coated with lime.
TYPE LOCATION: Malheur County, Oregon; 30 feet north of the county road and 60 feet west of the center line of section 27, in the SE1/4 SW1/4 corner of section 27, T. 18 S., R. 44 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 52 to 56 degrees F. The soils are usually dry but are moist for more than 60 days during the winter season. Depth to the duripan is 10 to 20 inches. Depth to very gravelly horizons is 20 to 40 inches. Depth to bedrock is 60 inches or more. The particle-size control section has 1 to 2 percent organic matter.
The A horizon has value of 3 or 4 moist and chroma of 2 or 3 dry and moist. It is silt loam or very fine sandy loam. It has 10 to 18 percent clay and less than 15 percent fine sand and coarser. It is mildly or moderately alkaline.
The Bw horizon has value of 3 or 4 moist and chroma of 2 or 3 dry and moist. It is silt loam or very fine sandy loam. It has 10 to 18 percent clay and less than 15 percent fine sand and coarser. It is mildly or moderately alkaline. In some pedons, this horizon may be weakly calcareous.
The Bqm horizon is silty and is indurated in the upper part. The lower part ranges from weakly to strongly cemented.
In some pedons, the silty, friable 2C and 2Ck horizons below the upper duripan are lacking. The underlying 2Ckqm very gravelly duripan is indurated or strongly cemented in the upper few inches becoming less cemented with increasing depth.
COMPETING SERIES: These are the
Arritola (T),
Chiara,
Coltroop,
Crooked,
Minveno,
Nevoyer,
Otoole,
Peeko,
Plegomir,
Scoon,
Tenvorrd, and
Yahoo (T) series. Arritola soils are fine-loamy above the duripan with 25 to 35 percent clay in the control section and lack the very gravelly horizons within a depth of 40 inches. Chiara soils lack a cambic horizon and do not have a very gravelly layer within 40 inches. Coltroop soils have 20 to 30 percent clay in the particle-size control section and are 30 to 35 inches to basalt bedrock. Crooked soils are sodic and are coarse-loamy above the duripan. Minveno soils have a calcic horizon above a duripan. Nevoyer soils are coarse-loamy and gravelly and are 9 to 20 inches deep to bedrock. Otoole soils are sodic, calcareous throughout, and lack the very gravelly horizons above a depth of 40 inches. Peeko soils have 15 to 35 percent rock fragments and 18 to 27 percent clay in the particle-size control section. Plegomir soils have more than 15 percent fine sand and coarser. Scoon soils contain 10 to 60 percent rock fragments in the Ck horizon above the duripan. Tenvorrd soils lack a cambic horizon and have 18 to 25 percent clay in the particle-size control section. Yahoo soils have 20 to 30 percent clay in the particle-size control section.
GEOGRAPHIC SETTING: Frohman soils are on nearly level to gently sloping terraces. Slopes are 0 to 20 percent. Elevation is 2100 to 3000 feet. The soils formed in silty lacustrine material and very gravelly alluvium of mixed origin. The climate is characterized by cool, moist winters and and hot, dry summers. The mean annual precipitation is 9 to 11 inches. The mean annual temperature is 50 to 54 degrees F. The mean summer temperature is 70 to 74 degrees F. and the mean winter temperature is 31 to 33 degrees F. The frost-free period is 130 to 170 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Nyssa,
Owyhee, and
Virtue soils. Nyssa soils are 20 to 40 inches deep to a duripan and lack the very gravelly duripan and C horizons within a depth of 40 inches. Owyhee soils lack duripans. Virtue soils have argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability above the duripan and very slow in the duripan.
USE AND VEGETATION: The soils are used for livestock grazing and irrigated crops. Irrigated small grains, alfalfa, pasture and occasional row crops are the principal crops. Vegetation is Sandberg bluegrass, bluebunch wheatgrass, big sagebrush, and annual forbs.
DISTRIBUTION AND EXTENT: MLRA 11. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Malheur County, Oregon. 1975.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon
Cambic horizon - from 8 to 12 inches (Bw horizon)
Duripan - from 12 to 18 inches (Bqm horizon)
Particle-size control section - from the surface to 12 inches (Ap and Bw horizons)
National Cooperative Soil Survey
U.S.A.