LOCATION AHART CA

Established Series
Rev. JWF/FOS/ET
01/2023

AHART SERIES

The Ahart series consists of moderately deep, well drained soils formed in material weathered from rhyolitic tuff. Ahart soils are on mountains and have slopes of 2 to 50 percent. The mean annual precipitation is 60 inches, and the mean annual temperature is 40 F.

TAXONOMIC CLASS: Medial, amorphic, frigid Humic Haploxerands

TYPICAL PEDON: Ahart gravelly sandy loam - on a southeast facing convex slope of 21 percent under white fir, Jeffrey pine, and red fir trees at 6,000 feet elevation. (Colors are for dry soil unless otherwise stated. When described on September 17, 1974, the soil was dry throughout).

01--2 to 0 inches; fresh and decomposed needles and leaves. (1 to 3 inches thick)

A1--0 to 8 inches; dark brown (10YR 3/3) gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine and medium granular structure; soft, very friable, nonsticky and nonplastic; few fine roots; many very fine interstitial pores; 16 percent pebbles; slightly acid (pH 6.5); clear irregular boundary. (3 to 9 inches thick)

A2--8 to 18 inches; brown (10YR 4/3) gravelly fine sandy loam, very dark grayish brown (10YR 3/2) moist; moderate medium and coarse subangular blocky structure; soft, very friable nonsticky and nonplastic; common very fine and fine, and many medium roots; many very fine and fine interstitial pores; 20 percent pebbles; moderately acid (pH 5.7); clear wavy boundary. (7 to 12 inches thick)

A3--18 to 31 inches; brown (10YR 5/3) gravelly fine sandy loam, dark brown (10YR 3/3) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine, fine, medium and coarse roots; many very fine and fine interstitial pores; 16 percent pebbles; strongly acid (pH 5.5); clear wavy boundary. (10 to 19 inches thick)

Cr--31 to 40 inches; weathered rhyolitic tuff, few roots in fractures (10 to 15cm apart).

TYPE LOCATION: Placer County, Tahoe National Forest, California, about one mile southeast of Ice Lakes and three-fourths of a mile into the Onion Creek Experimental Forest off the Baker Ranch-Soda Springs Road, near the center of the NE 1/4 sec. 2, T. 16 N., R. 14 E., MDB&M.

RANGE IN CHARACTERISTICS: Depth to a paralithic contact is 20 to 40 inches. Bulk density of the fine earth fraction is assumed to range from 1.0 to 0.85 gm/cc. The exchange complex is dominated by amorphous materials. The base saturation is between 25 and 50 percent throughout the profile. The thickness of the umbric epipedon ranges from 20 to 38 inches. Gravel content ranges from 15 to 35 percent throughout the soil. The mean annual soil temperature varies from 43 to 46 degrees F and summer temperature is greater than 47 degrees F. The soils are usually moist throughout but are dry in all parts between depths of 8 and 24 inches from late July until early October.

The A horizon has dry color of 10YR 3/3, 4/3 or 5/3 and moist color of 10YR 2/2, 3/2 or 3/3. It is sandy loam, fine sandy loam or loam and is gravelly. It has granular or subangular blocky structure and is strongly to slightly acid.

Some pedons have a C horizon with dry color of 10YR 4/3, 5/2, 5/3 or 5/4 and moist color of 10YR 3/2, 3/3. It is sandy loam, fine sandy loam or loam and is gravelly. It has subangular blocky structure or is massive and is strongly acid or slightly acid.

COMPETING SERIES: These are the Chemawa, Germany, Waca, Windy and Fiddletown soils in other families. Chemawa and Germany soils have a mesic temperature regime and are greater than 40 inches deep. Fiddletown, Waca and Windy soils have more than 35 percent rock fragments. Fiddletown soils are also mesic.

GEOGRAPHIC SETTING: The Ahart soils are on mountainous uplands. Slopes are 2 to 75 percent. They formed in material weathered from rhyolitic tuff of the Valley springs Formation. Elevations are 5,500 to 8,000 feet. The climate is typified by warm dry summers and cold moist winters. Mean annual precipitation is 50 to 70 inches, most of which occurs as snow. Mean January temperature is 27 degrees F; mean July temperature is 60 degrees F; and mean annual temperature varies from 38 to 42 degrees F. Frost-free season is 50 to 70 days.

GEOGRAPHICALLY ASSOCIATED SOILS: There are the Tallac soils and the competing Waca and Windy soils. The Tallac soils have more than 35 percent rock fragments in their control section.

DRAINAGE AND PERMEABILITY: Well drained, medium to rapid runoff; moderately rapid permeability.

USE AND VEGETATION: Used for watershed, timber production, and wildlife habitat. Vegetation is primarily semi-dense to dense stands of mixed conifers--mostly red fir, white fir, Jeffrey pine and western white pine.

DISTRIBUTION AND EXTENT: The mountain areas of central and northern California. The soil is not extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California

SERIES PROPOSED: Placer County (Tahoe National Forest), California, 1981.

REMARKS: The NaF test for amorphous materials showed light to deep pink. The test was run by the University of California at Davis. The Hach kit test for base saturation on a sample from near the paralithic contact showed 35 percent. This soil was originally proposed as a medial, frigid Umbric Vitrandept but is now being proposed as a medial, frigid Andic Xerumbrept. This soil is also Pachic however to parallel Haplumbrepts Andic will take precedence over Pachic.

Last revised by the state on 12/75.

Series reclassified 5/95. Competing series not updated at that time.

National Cooperative Soil Survey
U.S.A.