LOCATION MONTOUR ID
Established Series
Rev. RAC/GHL
01/2023
MONTOUR SERIES
The Montour series is a member of the fine, montmorillonitic, mesic family of Vertic Argixerolls. Typically, Montour soils have dark grayish brown, heavy clay loam A1 horizons, olive brown fine gravelly clay B2t horizons, and light gray and yellowish brown stratified, moderately and strongly calcareous Cca horizons over stratified, noncalcareous sand at depths of 38 inches.
TAXONOMIC CLASS: Fine, smectitic, mesic Vertic Argixerolls
TYPIFYING PEDON: Montour clay loam, grass. (Colors are for dry soil unless otherwise noted.)
A11--0 to 1 inch; dark grayish brown (2.5Y 4/2) clay loam, very dark gray (2.5Y 3/1) moist; weak medium platy that parts to strong fine granular structure; very hard, very firm, sticky, very plastic; common roots; slightly acid (pH 6.5); abrupt wavy boundary. (.5 to 2 inches thick)
A12--1 to 6 inches; dark grayish brown (2.5Y 4/2) heavy clay loam, very dark gray (2.5Y 3/1) moist; very coarse prisms 5 to 7 inches across that part to medium and coarse prisms that part to very weak medium platy structure; cracks .75 inches wide separate the very coarse prisms and small cracks separate the smaller prisms; extremely hard, very sticky, very plastic; few fine roots; few fine pores; accumulation of granules, sand and fine gravel in larger cracks; slightly acid (pH 6.5); clear wavy boundary. (5 to 8 inches thick)
AB--6 to 13 inches; dark grayish brown (2.5Y 4/2) clay, very dark gray (2.5Y 3/1) moist; very coarse prisms 6 to 10 inches across that part to strong coarse prismatic structure; vertical cracks up to 1 inch wide between very coarse prisms; extremely firm, very sticky, very plastic; few fine roots in cracks; thick continuous clay films on vertical faces of peds; granular material and some fine gravel in cracks; neutral (pH 6.7); gradual irregular boundary. (5 to 9 inches thick)
B2t--13 to 29 inches; olive brown (2.5Y 4/3) fine gravelly clay, olive brown (2.5Y 3/3) moist; dark gray (10YR 4/1) coatings on peds; strong coarse prismatic structure that parts to moderate coarse and medium angular blocky structure; extremely firm, very sticky, very plastic; few very fine roots in cracks; thick continuous clay films; neutral (pH 7.0); abrupt irregular boundary. (10 to 20 inches thick)
C1ca--29 to 32 inches; light gray (5Y 7/2) and yellowish brown (10YR 5/6) stratified coarse sandy loam, loamy sand, sand, and few thin strata of silty material, olive gray (5Y 4/2) moist; massive; friable; few very fine roots; few fine pores; common iron oxide stains and bands; intermittent, weakly cemented layer on upper 1 to 2 mm. of horizon; much rodent workings; strongly calcareous lime splotches between strata; slightly alkaline (pH 7.5); abrupt wavy boundary. (3 to 6 inches thick)
C2ca--32 to 38 inches; light gray (2.5Y 6/1) coarse sandy loam, dark grayish brown (2.5Y 4/2) moist; common medium distinct light yellowish brown (10YR 6/4) mottles, yellowish brown (10YR 5/4) moist; massive; firm; upper few millimeters very weakly cemented with a thin root mat on top; upper few inches moderately calcareous and lower part noncalcareous; slightly alkaline (pH 7.5); much muscovite; abrupt wavy boundary. (4 to 10 inches thick)
IIC3--38 to 50 inches; stratified sand with common iron oxide mottling; noncalcareous.
TYPE LOCATION: Gem County, Idaho; in a noncultivated area about 2 miles southeast of Sweet; 800 feet west and 200 feet north of the southeast corner of the NE1/4, section 10, T.7N., R.1E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is estimated to range from 48 degrees to 53 degrees F., and the mean summer soil temperature from 65 degrees to 72 degrees F. The soils are usually moist but are dry for 60 to 80 consecutive days in the 4 month period following the summer solstice. Bedrock, where present, is deeper than 60 inches. The A1 horizon has value of 3 through 5 dry, 2 through 4 moist, and chroma of 1 or 2. It has moderate or strong, very fine and fine granular structure. This horizon is slightly acid or neutral. The B2t horizon has hue of 2.5Y, 7.5YR or 10YR, value of 3 or 4 dry, 2 or 3 moist, and chroma of 2 or 3. It is silty clay, sandy clay, or clay. This horizon has moderate medium angular blocky to strong coarse prismatic structure. It has medium to thick continuous clay films on the vertical and horizontal faces of peds and has black staining on ped in the lower portion in some pedons. The B2t horizon is neutral or mildly alkaline. The Cca horizon is stratified with silt to sand. It has weakly cemented, intermittent or continuous layers between strata in some profiles. This horizon has weakly cemented, intermittent or continuous layers between strata in some profiles. This horizon is moderately or strongly calcareous, and mildly or moderately alkaline. Noncalcareous IIC3 horizons occur in some profiles. The stratified sand of this horizon has common iron oxide mottling.
COMPETING SERIES AND THEIR DIFFERENTIAE: These are the Banner (T), Battle Creek, Brent (T), Forsgren, Flowell, Gasset, Gem, Gemson, and Ukiah series. Banner, Brent, and Gemson soils do not have deep, wide cracks when dry. Battle Creek soils have mixed mineralogy. Forsgren soils do not have a strongly calcareous Cca horizon above depths of 40 inches. Gasset soils have over 60 percent clay in the fine earth fraction. Gem and Ukiah soils are less than 40 inches.
SETTING: The Montour soils are on rolling uplands and rounded hills. Slopes range from 0 to 60 percent, but typically are 5 to 15 percent. Elevations range from 2,500 to 4,000 feet. The soils formed in sediments derived from coarse-grained acid igneous rocks and tuffaceous materials. The climate is mediterranean and has a frost-free period of 110 to 160 days. The mean annual precipitation ranges from 11 to 16 inches, including 1 to 5 feet of snow.
PRINCIPAL ASSOCIATED SOILS: These are the Aikman, Haw, and Sweet soils and the competing Gem and Brent soils. Aikman soils have more than 60 percent clay in the fine earth fraction. Haw soils have less than 35 percent clay in the fine earth fraction. Sweet soils have a duripan at depths of less than 40 inches.
DRAINAGE AND PERMEABILITY: Well-drained; slow to rapid runoff; very slow permeability.
USE AND VEGETATION: Used chiefly for range, but some areas are used for small grains or alfalfa without irrigation. Vegetation is Idaho fescue, bluebunch wheatgrass, Sandberg bluegrass, cheatgrass, medusahead wildrye, wild sunflower, and wild parsnip.
DISTRIBUTION AND EXTENT: Southwestern Idaho. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Gem and Boise Counties, Idaho, 1938.
REMARKS: The soils formerly were classified as grumusolic Chestnut soils.
National Cooperative Soil Survey
U.S.A.