LOCATION ARSON ID

Established Series
Rev. BDG-RL-RJS
06/2016

ARSON SERIES

The Arson series consists of deep, well drained soils on side slopes, shoulders and ridge summits of foothills and low mountains. They formed in material from fine grained quartzites and siltite of the Libby, Striped Peak and Prichard formations of the Belt supergroup that is blanketed by a thin mantle of mixed volcanic ash and loess. Saturated hydraulic conductivity is moderately high. Slope ranges from 5 to 60 percent. The average annual temperature is about 43 degrees F. and the average annual precipitation is about 31 inches.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Vitrandic Haploxeralfs

TYPICAL PEDON: Arson ashy silt loam - forested - on a south-facing slope of 17 percent at 3,080 feet elevation. (Colors are for dry soil unless otherwise stated). When described on November 1, 2001, the soil was moist to 16 inches and dry below.

Oi--0 to 1 inch; slightly decomposed needles, twigs, leaves and moss. (0 to 1.5 inches thick)

A--1 to 6 inches; light brownish gray (10YR 6/2) ashy silt loam, very dark grayish brown (10YR 3/2) moist; weak fine and medium subangular blocky structure parting to moderate very fine and fine granular; slightly hard, very friable, nonsticky and nonplastic; common very fine roots throughout; common very fine tubular and irregular pores; 2 percent gravel; slightly acid (pH 6.4); abrupt wavy boundary. (3 to 9 inches thick)

BA--6 to 10 inches; light brownish gray (10YR 6/2) ashy silt loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; moderately hard, friable, slightly sticky and moderately plastic; common very fine roots between peds, few medium throughout; common very fine tubular and irregular pores; 2 percent gravel; moderately acid (pH 6.0); clear wavy boundary. (0 to 10 inches thick)

BEt--10 to 17 inches; pale brown (10YR 6/3) silt loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; hard, friable, slightly sticky and moderately plastic; common very fine and fine roots between peds; common very fine and medium tubular pores; few faint clay films on surfaces along pores; 5 percent gravel; moderately acid (pH 5.7); clear wavy boundary. (0 to 7 inches thick)

Bt1--17 to 22 inches; pale brown (10YR 6/3) silt loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; very hard, firm, moderately sticky and very plastic; common very fine and few fine roots between peds, few coarse throughout; common very fine tubular and irregular pores; common prominent clay films on surfaces along pores, many distinct clay films on vertical faces of peds; common prominent skeletans on vertical faces of peds; 5 percent gravel; moderately acid (pH 5.8); clear wavy boundary.

Bt2--22 to 28 inches; pale brown (10YR 6/3) gravelly silt loam, brown (10YR 4/3) moist; weak fine and medium prismatic structure parting to moderate fine and medium subangular blocky; very hard, firm, moderately sticky and very plastic; common very fine and fine roots between peds, few coarse throughout; common very fine tubular and irregular pores; many prominent clay films along surfaces of pores and on vertical faces of peds; many prominent skeletans on vertical faces of peds; 15 percent gravel; moderately acid (pH 5.9); clear wavy boundary. (Combined thickness of Bt horizons is 6 to 27 inches thick)

2BCt--28 to 33 inches; pale brown (10YR 6/3) gravelly silt loam, brown (10YR 4/3) moist; weak fine and medium prismatic structure parting to moderate fine and medium subangular blocky; very hard, firm, nonsticky and slightly plastic; common very fine roots between peds; common very fine tubular and few very fine irregular pores; common prominent clay films on vertical faces of peds and on rock fragments; common prominent skeletans on vertical faces of peds; 15 percent gravel; moderately acid (pH 5.9); clear wavy boundary. (Combined thickness of 2Bt and/or 2BC horizons is 5 to 19 inches)

2C--33 to 48 inches; 70 percent light gray (10YR 7/2), 15 percent pale brown (10YR 6/3) and 15 percent brown (7.5YR 4/3) extremely gravelly silt loam, 70 percent pale brown (10YR 6/3), 15 percent yellowish brown (10YR 5/4) and 15 percent brown (7.5YR 4/3) moist; massive; moderately hard, friable, nonsticky and slightly plastic; common very fine and fine roots; common very fine tubular pores; common prominent clay films on rock fragments; 75 percent gravel and 10 percent paragravel; moderately acid (pH 6.0); abrupt wavy boundary. (0 to 26 inches thick)

2Cr--48 to 60 inches; fractured siltite.

TYPE LOCATION: Latah County, Idaho; about 3 miles north and 4 miles east of Potlatch, Idaho; about 2,300 feet south and 2,100 feet west of the northeast corner of Sec. 22, T42N, R4W; Latitude 46 degrees, 58 minutes, 9 seconds North and Longitude 116 degrees 49 minutes, 12 seconds West; UTM Zone 11 Northing 5201722 meters and Easting 0513581 meters; USGS Princeton Quadrangle.

RANGE IN CHARACTERISTICS:

Solum thickness 48 to 60 inches
Soil moisture control section - usually dry for 45 to 90 consecutive days during June to October.
Xeric moisture regime.
Average annual soil temperature - 41 to 46 degrees F.
Frigid temperature regime.
Particle size control section the upper 20 inches of the argillic horizon averages greater than 18 percent clay content.
Depth to paralithic contact 40 to 60 inches.
Depth to skeletal material ranges from 84 to 127cm (33 to 50 inches)

A horizon
Value - 4 to 6 dry, 2 or 3 moist
Chroma - 2 or 3 dry and 1 to 3 moist
Texture - ashy silt loam
Clay content - 10 to 18 percent
Rock fragments - 0 to 5 percent gravel
Reaction - 5.6 to 6.5
Volcanic glass in the 0.02 to 2.0 mm fraction - 5 to 25 percent
Acid-oxalate extractable Al+1/2Fe - 0.4 to 1.0 percent

AB, BA and Bw horizons
Value - 5 or 6 dry, 3 or 4 moist
Chroma - 3 or 4 dry
Texture - ashy silt loam
Clay content - 10 to 23 percent
Rock fragment - 0 to 5 percent gravel
Reaction - 5.6 to 6.5
Volcanic glass in the 0.02 to 2.0 mm fraction - 5 to 25 percent
Acid-oxalate extractable Al+1/2Fe - 0.4 to 1.0 percent

E and EB horizons (where present)
Value - 6 or 7 dry, 4 or 5 moist
Chroma - 2 to 4 dry or moist
Texture - silt loam
Clay content - 17 to 23 percent
Rock fragments - 0 to 5 percent gravel
Reaction - 5.6 to 6.0

Bt and BE horizons
Value - 5 to 8 dry and 4 or 5 moist
Chroma - 2 to 4 dry or moist
Texture - silt loam
Clay content - 14 to 26 percent
Rock fragments - 0 to 10 percent gravel
Pararock fragments - 0 to 8 percent paragravel
Reaction - 5.1 to 6.0

2Bt and 2BCt horizons
Hue - 7.5YR or 10YR dry, 7.5YR to 2.5Y moist
Value - 5 to 7 dry and 4 or 5 moist
Chroma - 3 to 6 dry or moist
Texture - silt loam or loam
Clay content - 10 to 26 percent
Rock fragments - 15 to 50 percent gravel, 0 to 10 percent cobbles
Pararock fragments - 0 to 20 percent paragravel
Reaction - 5.1 to 6.0

2C horizons (when present)
Hue - 7.5YR or 10YR dry, 7.5YR to 2.5Y moist
Value - 4 to 7 dry and 4 to 6 moist
Chroma - 2 to 6 dry, 3 to 6 moist
Texture - very fine sandy loam, silt loam or loam
Clay content - 8 to 17 percent
Rock fragments - 35 to 85 percent gravel, 0 to 5 percent cobbles
Pararock fragments - 10 to 35 percent paragravel
Reaction - 5.4 to 6.2

COMPETING SERIES:

Kakyaticham - moderately deep to a lithic contact and contain fragments of basalt bedrock.
Seddow - contains fragments of basalt bedrock.

GEOGRAPHIC SETTING: The Arson soils are on side slopes, shoulders and ridge summits of foothills and low mountains. Slopes range from 8 to 65 percent. These soils formed in fine grained quartzites or siltite with a thin mantle of mixed volcanic ash and loess at elevations of 2,250 to 4,310 feet (686 to 1314 meters). The average annual air temperature ranges from 40 to 49 degrees F, with an average annual precipitation of 23 to 37 inches (584 to 940 mm). The frost free season is 95 to 130 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are Stewah (T), Carlinton, Sinkler (T) and Carrico (T) soils. Stewah soils have a udic moisture regime and are on side slopes of foothills and low mountains. Carlinton soils have a fragipan and are on hillsides and summits of broad intrerfluves. Sinkler soils are very deep and are on linear and concave backslopes of foothills and low mountains. Carrico soils are moderately deep, do not have siltite fragments and parafragments in the subsoil and are on mountain side slopes and ridges.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; moderately high saturated hydraulic conductivity.

USE AND VEGETATION: These soils are used for timber production, livestock grazing, wildlife habitat, watershed, and recreation. Potential natural vegetation is Douglas-fir, grand fir and ponderosa pine with an understory of oceanspray, mallow ninebark, pinegrass, common snowberry, dwarf rose, white spirea, American trailplant and woodland strawberry.

DISTRIBUTION AND EXTENT: North-central Idaho. The series is moderately extensive. MLRA 43A and 9.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Latah County, Idaho, 2013.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 10 inches (Oi, A and BA horizons).
Argillic horizon - The zone from 10 to 33 inches (BEt, Bt1, Bt2 and 2BCt horizons).
Vitrandic feature - The zone from 1 to 10 inches (A and BA horizons).
Particle-size control section - The zone from 10 to 30 inches (BEt, Bt1, Bt2, and part of the 2BCt horizons).

The 4/2011 revision reflects a change in family from fine-silty to fine-loamy based on a review of field and laboratory data.

Additional Data: Laboraory data are available for this series: NSSL pedon ID S04ID057015, Pedon No. 04N1097, from Latah County, Idaho.

National Cooperative Soil Survey
U.S.A.