LOCATION FENN IDEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Typic Haploxererts
TYPICAL PEDON: Fenn clay, cultivated. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 6 inches; very dark gray (10YR 3/1) silty clay, black (10YR 2/1) moist; strongly very fine and fine granular structure; very hard, firm, very sticky and very plastic; few very fine roots; slightly acid (pH 6.5); abrupt smooth boundary. (4 to 8 inches thick)
B1t--6 to 17 inches; very dark gray (10YR 3/1) clay, black (10YR 2/1) moist; strong fine angular blocky structure; very hard, firm, very sticky and very plastic; few very fine roots; common very fine tubular pores; many thin clay films on surfaces of pores; many slickensides and wedge-shaped aggregates oriented 50 degrees from the horizontal, many intersect; neutral (pH 6.8); gradual wavy boundary. (7 to 13 inches thick)
B21t--17 to 27 inches; dark grayish brown (10YR 4/2) clay, dark brown (10YR 3/3) moist; strong fine and medium angular blocky structure; extremely hard, firm, very sticky and very plastic; few very fine roots; common very fine tubular pores; many thin clay films on surfaces of pores; very few iron and manganese concretions up to 2 mm. in diameter; many slickensides and wedge-shaped aggregates oriented 50 degrees from the horizontal, many intersect; neutral (pH 7.1); gradual wavy boundary. (6 to 12 inches thick)
B22tca--27 to 39 inches; brown (10YR 5/3) clay, dark brown (10YR 4/3) moist; strong moderate and coarse angular blocky structure; very hard, friable, very sticky and very plastic; few very roots; common very fine tubular pores; many thin clay films on surfaces of pores; very few iron and manganese concretions up to 2 mm. in diameter; many slickensides and wedge-shaped aggregates oriented 50 degrees from horizontal, many intersect; slightly calcareous; moderately alkaline (pH 8.2); gradual wavy boundary. (9 to 15 inches thick)
B23tca--39 to 63 inches; dark brown (10YR 4/3) clay, dark brown (10YR 4/3) moist; strong moderate and coarse angular blocky structure; extremely hard, firm, very sticky and very plastic; few very fine roots; common very fine tubular pores; many thin clay films on surfaces of pores; very few iron and manganese concretions up to 2 mm. in diameter; many slickensides and wedge-shaped aggregates oriented 50 degrees from horizontal, many intersect; few filled rodent-like holes about 5 cm. in diameter; slightly calcareous; moderately alkaline (pH 8.4).
TYPE LOCATION: Idaho County, Idaho; 418 feet south (from center of intersection) and 92 feet west (from center of road of the E1/4 corner of section 31, T.31N., R.2E.
RANGE IN CHARACTERISTICS: Depth to bedrock is more than 40 inches and usually more than 60 inches. Thickness of the mollic epipedon ranges from 18 to 32 inches. Cracks 1 mm. wide or larger extend to a depth of 24 inches or more. Cracks remain open for more than 60 consecutive days in late summer in most years and remain closed during the winter. Depth to segregated lime ranges from 20 to 40 inches. Mean annual soil temperature ranges from 47 degrees to 49 degrees F., and the mean summer soil temperature ranges from 59 degrees to 61 degrees F.
Ap horizon has hue of 10YR or 2.5Y and dry value of 3 or 4. It is silty clay, clay or silty clay loam and has 30 to 60 percent clay.
The B2 horizon has value of 4 through 6 dry and 3 through 5 moist and chroma of 2 through 4. It is silty clay or clay and has less than 60 percent clay.
COMPETING SERIES: These are the Cardon and Pit series. Cardon soils are generally saturated within 30 inches of the surface, mottled below a depth of 20 inches, and strongly calcareous. Pit soils have thick dark gray A horizons, are somewhat poorly and poorly drained and have mottles below a depth of 40 inches.
GEOGRAPHIC SETTING: Fenn soils are on plateaus and have gradients of 0 to 25 percent. They formed in loess and possibly residuum weathered from Columbia River Basalt. Elevations are 2,800 to 3,600 feet. The mean annual precipitation ranges from 20 to 24 inches. The mean annual temperature is 45 degrees to 47 degrees F. The frost-free period is 105 to 135 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ferdinand and Nez Perce soils. Ferdinand soils have more than 35 percent rock fragments in the textural control section. Nez Perce soils have an abrupt textural change between the A and B horizons.
DRAINAGE AND PERMEABILITY: Well drained; medium or rapid runoff; slow or very slow permeability.
USE AND VEGETATION: The soils are cultivated. Wheat, peas, barley, hay and pasture are the principal crops. The natural vegetation is mainly Idaho fescue, biscuitroot, cinquefoil and yarrow.
DISTRIBUTION AND EXTENT: Loess-covered basaltic areas of northern Idaho. Inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Idaho County (West Idaho County Soil Survey Area), Idaho, 1976.