LOCATION JAHJO CA

Established Series
Rev. DWB/CAF/JJJ
12/2022

JAHJO SERIES

The Jahjo series consists of shallow, well drained soils formed in tephra. Jahjo soils are on lava ridges and in pockets between lava flows. Slopes range from 2 to 15 percent. The mean annual precipitation is about 20 inches and the mean annual temperature is about 46 degrees F.

TAXONOMIC CLASS: Loamy, mixed, superactive, mesic Lithic Dystroxerepts

TYPICAL PEDON: Jahjo extremely cobbly fine sandy loam on a southwest facing 2 percent slope under a cover of prostrate ceanothus, antelope bitterbrush, mountain big sagebrush and ponderosa pine at an elevation of 4260 feet. (Colors are for dry soil unless, otherwise stated. When described May 3, 1984, the soil was moist to 12 inches.)

A1--0 to 2 inches; brown (10YR 5/3) extremely cobbly fine sandy loam, very dark grayish brown (10YR 3/2) moist; weak very fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; few very fine roots; few very fine interstitial pores; 70 percent cobbles; NaF pH 10.5; moderately acid (pH 6.0); abrupt smooth boundary. (2 to 4 inches thick)

A2--2 to 6 inches; brown (10YR 5/3) fine sandy loam, dark brown (7.5YR 3/2) moist; weak very fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine roots; few very fine interstitial pores; 10 percent gravel; NaF pH 11.0; slightly acid (pH 6.5); abrupt smooth boundary. (2 to 6 inches thick)

Bw--6 to 12 inches; yellowish brown (10YR 5/4) loam, dark brown (10YR 3/3) moist; moderate fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; few very fine roots; few very fine interstitial pores; 10 percent gravel; NaF pH 11.5; slightly acid (pH 6.5); abrupt smooth boundary. (6 to 8 inches thick)

2R--12 inches; hard basalt.

TYPE LOCATION: Modoc County, California about 9 miles southwest of Tionesta; 600 feet east and 800 feet south of the northwest corner of sec. 6, T. 42 N., R. 6 E., Timber Mtn. SE (Kephart) quadrangle (7.5 minute series).

RANGE IN CHARACTERISTICS: Depth to a lithic contact is 10 to 14 inches. The mean annual soil temperature is 47 to 50 degrees F. The soil temperature exceeds 41 degrees F from mid March to late December (285 days) and exceeds 47 degrees F from early May to early December. The soil moisture control section is dry in all parts from early June to late September and is moist in all parts from early November to early May. The particle-size control section averages 10 to 18 percent clay and 10 to 15 percent rock fragments, mostly gravel. Rock fragments, mostly cobbles on the surface, range from 35 to 75 percent.

The A horizon color is 10YR 5/2, 5/3, or 5/4. Moist color is 10YR 2/1, 3/1, 3/2, 3/3, or 7.5YR 3/2. Clay content ranges from 10 to 12 percent. Rock fragments, mostly cobbles or gravel, range from 10 to 80 percent. Organic matter ranges from 2 to 5 percent. Base saturation by ammonium acetate ranges from 25 to 36 percent. NaF pH ranges from 10.5 to 11.5. Reaction ranges from slightly acid to moderately acid.

The Bw horizon color is 10YR 5/2, 5/3, 5/4 or 7.5YR 4/4. Moist color is 10YR 3/2, 3/3 or 7.5YR 3/2. Clay content ranges from 12 to 18 percent. Rock fragments, mostly gravel, range from 10 to 15 percent. Organic matter ranges from 1 to 3 percent. Base saturation by ammonium acetate ranges from 35 to 50 percent. NaF pH ranges from 10.5 to 12.0.

Andic property data (see remarks for explanation):
Depth P-ret B.D. pH NaF Glass Alo Feo 15 barH20 0-2 72 ND 10.5 9 1.14 1.00 14.1 2-6 75 ND 11.0 8 1.48 0.97 16.3 6-12 71 ND 11.5 5 0.81 0.77 18.9

COMPETING SERIES: This is the Ledmount (CA) series. The Ledmount soils have mean annual soil temperatures that are 54 to 59 degrees F.

GEOGRAPHIC SETTING: Jahjo soils are on lava ridges and in pockets between lava flows. Slopes are 2 to 15 percent. These soils formed in tephra. Elevation is 4,100 to 4,400 feet. The climate is semiarid with warm dry summers and cold moist winters. Mean annual precipitation is 16 to 25 inches. Snowfall is 48 to 60 inches. The mean annual temperatures is 45 to 48 degrees F. The mean January temperature is about 32 degrees F. The mean July temperature is about 65 degrees F. Frost-free period is 80 to 100 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Longbell and Loveness soils. Longbell soils are on lava plateaus, are deep, are medial over sandy or sandy skeletal, and have umbric epipedon. Loveness soils are on lava plateaus, are deep, have argillic horizon, are medial over loamy and have a mollic epipedon.

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

USE AND VEGETATION: This soil is used for wildlife habitat.. The vegetation is prostrate ceanothus, antelope bitterbrush, mountain big sagebrush, ponderosa pine, bottlebrush squirreltail, curlleaf mountain mahogany.

DISTRIBUTION AND EXTENT: Northeastern California. The soils are not extensive. MLRA is 22B.

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

SERIES ESTABLISHED: Modoc County, Intermountain Soil Survey Area, California 1994. Source of name is coined.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Umbric epipedon - the zone from 0 to 12 inches (A1, A2, Bt)

Andic properties data definitions:

P-ret: phosphate retention of the less than 2mm fraction.

B.D.: bulk density of the less than 2mm fraction on an oven dry basis.

pH NaF: pH of soil mixed with saturated sodium floride solution.

Glass: percent volcanic glass.

Alo: acid-oxalate-extractable aluminum of the less than 2mm fraction.

Feo: acid-oxalate-extractable iron of the less than 2mm fraction.

15 bar H20: dried 1500 kPa water retention as a percent.

Data elements with a * are estimated.

NC: not calculated.

ND: not done.

ADDITIONAL DATA: This pedon was characterized by UC Davis in 1986, UCD Pedon #1646. Sample number 86-049-5-1 unpublished.

National Cooperative Soil Survey
U.S.A.