LOCATION SECUNDA                 ID

Established Series
Rev. BDG-JAL-EMM
07/2013

SECUNDA SERIES

The Secunda series consists of very deep, well drained soils on mountain side slopes and ridges. They formed in material from quartzite and phyllite of the Wallace Formation of the Belt supergroup that is blanketed by a thick mantle of volcanic ash. Saturated hydraulic conductivity is moderately high. Slope ranges from 10 to 75 percent. The average annual temperature is about 43 degrees F. and the average annual precipitation is about 39 inches.

TAXONOMIC CLASS: Ashy over loamy, amorphic over isotic, frigid Alfic Udivitrands

TYPICAL PEDON: Secunda ashy silt loam - forested - on a northeast-facing slope of 54 percent at 3,350 feet elevation. (Colors are for dry soil unless otherwise noted). When described on July 11 2002, the soil was dry throughout.

Oi--0 to 1 inch; slightly decomposed needles, twigs, leaves and moss.

Oe--1 to 3 inches; moderately decomposed needles, twigs, leaves and moss. (Combined thickness of O horizons is 1 to 4 inches)

A--3 to 7 inches; brown (7.5YR 5/3) ashy silt loam, very dark brown (7.5YR 2.5/3) moist; moderate very fine and fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine and common fine and medium roots; common very fine irregular pores; moderately acid (pH 6.0); clear wavy boundary. (1 to 4 inches thick)

Bw1--7 to 13 inches; brown (7.5YR 5/4) ashy silt loam, dark brown (7.5YR 3/4) moist; weak very fine and fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine, common fine and medium and few coarse roots; common very fine irregular pores; neutral (pH 6.6); clear wavy boundary.

Bw2--13 to 19 inches; light yellowish brown (10YR 6/4) ashy silt loam, dark yellowish brown (10YR 3/4) moist; weak very fine, fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine, common fine and medium, and few coarse and very coarse roots; few very fine irregular and tubular pores; neutral (pH 6.6); abrupt wavy boundary. (Combined thickness of Bw horizons is 10 to 18 inches)

2Bt--19 to 31 inches; light brown (7.5YR 6/3) fine sandy loam, dark brown (7.5YR 3/4) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and few fine, medium, coarse and very coarse roots; many very fine and few fine, medium and coarse tubular pores; common faint clay films on vertical faces of peds; common faint silt coats on surfaces along pores; 1 percent fine mica flakes; 5 percent gravel; neutral (pH 6.7); abrupt broken boundary. (12 to 38 inches thick)

2BCt--31 to 39 inches; light yellowish brown (10YR 6/4) loamy sand, dark yellowish brown (10YR 4/6) moist; weak fine and medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common very fine and few fine and medium roots; few very fine tubular and irregular pores; common faint clay films on surfaces along pores and on vertical faces of peds, common faint silt coats on surfaces along pores; 3 percent fine mica flakes; 10 percent gravel; slightly acid (pH 6.4); clear wavy boundary. (0 to 15 inches thick)

3C1--39 to 50 inches; 70 percent light yellowish brown (10YR 6/4) and 30 percent reddish yellow (7.5YR 6/8) gravelly loamy sand, 70 percent dark yellowish brown (10YR 4/6) and 30 percent strong brown (7.5YR 5/8) moist; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine and fine roots; common very fine tubular pores; 5 percent fine mica flakes; 15 percent gravel; slightly acid (pH 6.2); gradual wavy boundary.

3C2--50 to 64 inches; 50 percent yellow (10YR 7/6) and 50 percent reddish yellow (7.5YR 6/8) very gravelly sand, 50% dark yellowish brown (10YR 4/6) and 50 percent strong brown (7.5YR 5/8) moist; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine and fine roots; common very fine tubular pores; 4 percent fine mica flakes; 40 percent gravel; strongly acid (pH 5.5); clear wavy boundary.

3C3--64 to 73 inches; 60 percent yellow (10YR 7/6), 40 percent yellowish brown (10YR 5/8) gravelly loamy sand, 60 percent dark yellowish brown (10YR 4/6) and 40 percent yellowish brown (10YR 5/8) moist; massive; slightly hard, friable, nonsticky and nonplastic; few very fine roots; few very fine tubular and common very fine irregular pores; 5 percent fine mica flakes; 30 percent gravel; strongly acid (pH 5.2).

TYPE LOCATION: Latah County, Idaho; about 2 miles north and 9 miles east of Harvard, Idaho; about 450 feet south and 170 feet east of the northwest corner of Sec. 36, T42N, R2W; Latitude 46 degrees, 56 minutes, 57 seconds North and Longitude 116 degrees 32 minutes, 37 seconds West; UTM Zone 11 Northing 5199616 meters and Easting 0534730 meters; USGS Sand Mountain Quadrangle.

RANGE IN CHARACTERISTICS:

Solum thickness - 32 to greater than 60 inches
Soil moisture control section - usually moist year around and not dry for 45 consecutive days during June to October.
Udic moisture regime.
Average annual soil temperature - 39 to 45 degrees F.

Volcanic ash cap thickness - 14 to 21 inches
Volcanic glass content in the 0.02 to 2.0 mm fraction - 15 to 60 percent
Acid-oxalate extractable Al plus 1/2 Fe - 1.3 to 2.7 percent
Phosphate retention - 75 to 90 percent
15-bar water retention on air dried samples - 9 to 13 percent (weighted average is less than 12 percent)
Moist bulk density - 0.60 to 0.95 g/cc

A horizon
Hue - 7.5YR or 10YR dry or moist
Value - 2.5 or 3 moist
Chroma - 3 or 4 dry and 2 to 6 moist
Clay content - 5 to 10 percent
Rock fragments - 0 to 5 percent gravel
Reaction - 5.6 to 6.5

Bw horizons
Hue - 7.5YR or 10YR dry or moist
Value - 5 to 7 dry, 3 to 5 moist
Chroma - 4 to 6 dry or moist
Clay content - 5 to 10 percent
Rock fragment - 0 to 5 percent gravel
Reaction - 5.6 to 6.5

2Bt horizons
Hue - 7.5YR to 2.5Y dry, 7.5YR or 10YR moist
Value - 6 or 7 dry and 3 to 5 moist
Chroma - 3 to 6 dry or moist
Texture - loam or fine sandy loam
Clay content - 6 to 18 percent
Sand content - less than 15 percent very coarse and coarse sand and more than 40 percent very fine sand and fine sand
Rock fragments - 2 to 20 percent gravel
Mica content - 0 to 5 percent
Reaction - 5.1 to 6.5

2BC and 2BCt horizons
Hue - 10YR or 2.5Y dry, 7.5YR to 2.5Y moist
Value - 6 or 7 dry and 4 to 6 moist
Chroma - 4 or 6 dry or moist
Texture - fine sandy loam, loamy fine sand or loamy sand
Clay content - 4 to 17 percent
Sand content - less than 15 percent very coarse and coarse sand and more than 40 percent very fine sand and fine sand
Rock fragments - 8 to 25 percent gravel, 0 to 10 percent cobbles, 8 to 25 percent total rock fragment content
Mica content - 0 to 10 percent
Reaction - 5.1 to 6.5

2C horizons
Hue - 7.5YR to 2.5Y dry or moist
Value - 5 to 8 dry and 4 to 6 moist
Chroma - 3 to 8 dry, 4 to 8 moist
Texture - fine sandy loam, very fine sandy loam or loamy sand
Clay content - 3 to 15 percent
Sand content - less than 15 percent very coarse and coarse sand and more than 40 percent very fine sand and fine sand
Rock fragments - 10 to 35 percent gravel, 0 to 10 percent cobbles, 10 to 35 percent total rock fragment content
Pararock fragments - 0 to 15 percent paragravel
Mica content - 0 to 35 percent
Reaction - 5.1 to 6.0

COMPETING SERIES:

Dowper soils: have 19 to 31 percent clay in the 2Bt horizon.

Jacot soils: have more than 15 percent coarse and very coarse sand in material beneath the ash cap.

Mackatie soils: are deep to a paralithic contact.

Tamara soils: have 20 to 35 percent clay in the 2Bt horizon.

Tomodo soils: have fragic characteristics at 20 to 51 inches.

Turpentine soils: have a lithic contact within 70 inches (178 cm); have a surface layer with andic soil properties that is 21 to 25 inches (53 to 64 cm) thick

GEOGRAPHIC SETTING: The Secunda soils are on mountain sides. Slopes range from 10 to 75 percent. These soils formed in quartzite or phyllite with a thick mantle of volcanic ash at elevations of 2,710 to 5,048 feet (827 to 1539 meters). The average annual temperature ranges from 40 to 46 degrees F, with an average annual precipitation of 36 to 48 inches (914 to 1219 mm). The frost free season is 50 to 120 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are Disalto, Flewsie and Bouldercreek soils. Disalto soils have a horizon formed in loess and are on mountain sides and ridge summits. Flewsie soils lack evidence of clay movement and are on steep mountain sides. Bouldercreek soils have more than 35 percent rock fragments below an ash cap and are on steep mountain sides.

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 western red cedar, grand fir, western hemlock, western larch, western white pine, and Douglas-fir with an understory of queencup beadlily, longtube twinflower, one-sided wintergreen, princes pine, common snowberry and myrtle boxwood.

DISTRIBUTION AND EXTENT: North-central Idaho. The series is not extensive. MLRA 43A.

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 mineral soil surface to 7 inches (A horizon).

Cambic horizon The zone from 7 to 19 inches (Bw1 and Bw2 horizons).

Argillic horizon - The zone from 9 to 39 inches (2Bt and 2BCt horizons).

Andic soil properties - The zone from 3 to 19 inches (A, Bw1 and Bw2 horizons).

Particle-size control section - The zone from 3 to 43 inches (A, Bw1, Bw2, 2Bt, 2BCt and part of the 2C1 horizons).

ADDITIONAL DATA: Laboratory data exists for this pedon:
Laboratory pedon number 02N1050 and soil survey pedon ID number S02ID-057-008

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National Cooperative Soil Survey
U.S.A.