LOCATION POTWISHA CA

Established Series
JBB/CES/JTW
09/2021

POTWISHA SERIES

The Potwisha series consists of shallow, well drained soils formed in colluvium over residuum derived from marble. Potwisha soils are on hillslopes and canyon walls. Slopes range from 30 to 100 percent. Mean annual precipitation is about 720 mm and the mean annual air temperature is about 16 degrees C.

TAXONOMIC CLASS: Loamy, mixed, superactive, thermic Lithic Ultic Haploxerolls

TYPICAL PEDON: Potwisha gravelly sandy loam on an east-facing (90 degree), 47 percent slope under a canopy of interior live oak, yucca, and chamise at an elevation of 660 meters. (Colors are for dry soils unless otherwise noted. When described on February 21, 2013 the soil was moist throughout.)

Oi--0 to 2 cm; slightly decomposed plant material; clear wavy boundary. (0 to 4 cm thick)

A--2 to 10 cm; brown (10YR 4/3) gravelly sandy loam, dark brown (10YR 3/3) moist; 8 percent clay; weak medium subangular blocky parting to weak medium granular structure; soft, very friable, nonsticky, nonplastic; many very fine roots throughout; many very fine irregular pores; 20 percent subangular indurated marble gravel, 3 percent subangular indurated marble cobbles; very slight effervescence; neutral (pH 7.2); clear smooth boundary. (7 to 26 cm thick)

Bk--10 to 42 cm; brown (10YR 5/3) gravelly sandy loam, dark brown (10YR 3/3) moist; 12 percent clay; moderate medium subangular blocky parting to moderate fine subangular blocky structure; slightly hard, very friable, nonsticky, nonplastic; many very fine and common fine roots throughout; many very fine irregular and common very fine dendritic tubular pores; 25 percent carbonate coats on bottom of rock fragments; 15 percent subangular indurated marble gravel, 10 percent subangular indurated marble cobbles, 1 percent subangular indurated marble stones; slight effervescence; neutral (pH 7.0); abrupt smooth boundary. (10 to 35 cm thick)

R--42 to 52 cm; indurated marble bedrock.

TYPE LOCATION: Tulare County, California, approximately 250 m southwest of Potwisha Campground in Sequoia National Park; USGS 7.5 minute topographic quadrangle: Giant Forest, California; WGS84 36.515883 latitude and -118.803100 longitude; UTM zone 11 4042682 meters N 338548 meters E NAD83.

RANGE IN CHARACTERISTICS:
Soil temperature: The mean annual soil temperature at 50 cm is 15 to 17 degrees C and the difference between mean summer and mean winter soil temperature is greater than 6 degrees C. The soils have a thermic temperature regime.

Soil moisture: The soils have a xeric soil moisture regime. The soil moisture control section is dry from about May to October (about 150 days).

Diagnostic Feature(s):
Mollic epipedon thickness: 18 to 50 cm
Depth to lithic contact: 20 to 50 cm

Reaction: neutral to moderately alkaline

Base saturation: greater than 50 percent in the epipedon (by ammonium acetate), and 50 to 75 percent in one or more horizons between the mineral soil surface and the lithic contact (by sum of cations)

Particle size control section weighted average:
Rock fragments: 15 to 35 percent, with 15 to 35 percent gravel, 0 to 10 percent cobbles, and 0 to 5 percent stones
Clay content: 7 to 12 percent

A horizon
Hue: 7.5YR, 10YR
Value: 4 or 5 dry, 3 moist
Chroma: 2 to 4 dry, 2 or 3 moist
Texture: sandy loam, fine sandy loam
Clay content: 6 to 13 percent
Rock fragments: 5 to 50 percent
5 to 25 percent gravel
0 to 10 percent cobbles
0 to 10 percent stones

Bk horizon
Hue: 7.5YR, 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 3 dry, 2 or 3 moist
Texture: sandy loam, fine sandy loam
Clay content: 7 to 15 percent
Rock fragments: 15 to 60 percent
15 to 30 percent gravel
0 to 30 percent cobbles
0 to 40 percent stones

COMPETING SERIES: There are no other series in this family at this time.

GEOGRAPHIC SETTING: The Potwisha soils are on linear to convex backslopes on hills, mountain slopes and canyon walls. Slopes are 30 to 100 percent. These soils formed in colluvium over residuum derived from marble. Elevations are 540 to 1840 meters. The climate is Mediterranean with warm, dry summers and cool, moist winters. The mean annual precipitation is 695 to 1015 mm and the mean annual air temperature is 13 to 17 degrees C. The frost free season is 200 to 270 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Andregg, Ashmountain, and Millvilla soils. Andregg soils are on similar landform positions and have a granitic paralithic contact between 50 and 100 cm. Ashmountain soils are on backslopes of high hills and mountain slopes and do not have bedrock within the series control section. Millvilla soils are on similar landform positions and are 50 to 100 cm to a metasedimentary lithic contact.

DRAINAGE AND PERMEABILITY: Well drained; high saturated hydraulic conductivity throughout the soil profile. Saturated hydraulic conductivity of the bedrock is very low to moderately high.

USE AND VEGETATION: This soil is used for recreation, wildlife habitat, and watershed. Vegetation is chamise, yucca, interior live oak, yerba santa, and mountain mahogany.

DISTRIBUTION AND EXTENT: Sierra Nevada Foothills of California; MLRA 18. These soils are not extensive.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Davis, California

SERIES PROPOSED: Tulare County, California, Sequoia and Kings National Parks. Source of name from a campground in Sequoia National Park.

REMARKS:
Particle Size Control Section for this pedon: 27 to 42 cm
Diagnostic horizons and features recognized in this pedon are:
Mollic Epipedon 0 to 42 cm
Lithic Contact 42 cm

ADDITIONAL DATA:
NASIS User Pedon ID: 2013CA7927003

Soil classified using the 12th Edition of the Keys to Soil Taxonomy.

National Cooperative Soil Survey
U.S.A.