LOCATION POKONAHBE CA
Established Series
Rev. PWB-ET-MAV
06/2016
POKONAHBE SERIES
The Pokonahbe series consists of very deep, somewhat poorly drained soils formed in alluvium from mixed rock sources and lacustrine sediments. Pokonahbe soils are on stream terraces and lacustrine terraces and have slopes of 0 to 5 percent. The mean annual precipitation is about 130 mm and the mean annual temperature is about 15 degrees C.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Xeric Haplargids
TYPICAL PEDON: Pokonahbe loamy fine sand, on a nearly level slope of 1 percent under alkali sacaton, greasewood, and rabbitbrush at an elevation of 1,152 meters. (When described on January 24, 1985, the soil was dry to 8 cm and moist below. Colors are for dry soil unless otherwise stated.).
An1--0 to 8 cm; light brownish gray (2.5Y 6/2) loamy fine sand, dark grayish brown (2.5Y 4/2) moist; weak medium platy structure; soft, very friable, nonsticky and nonplastic; common very fine and few fine and medium roots; few very fine interstitial pores; strongly effervescent; 2 percent gravel 2 to 5 mm in diameter; very strongly alkaline (pH 9.2); clear smooth boundary.
An2--8 to 20 cm; light brownish gray (2.5Y 6/2) fine sandy loam, olive brown (2.5Y 4/4) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine, common fine and few medium roots; common very fine tubular and interstitial pores; strongly effervescent; 2 percent gravel 2 to 5 mm in diameter; strongly alkaline (pH 9.0); clear smooth boundary. (Combined thickness of the An horizons is 8 to 43 cm)
2BAtn--20 to 36 cm; light yellowish brown (2.5Y 6/4) loam, olive brown (2.5Y 4/4) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine, common fine and few medium roots; common very fine tubular and interstitial pores; few faint clay films bridging mineral grains and on faces of peds; slightly effervescent; very strongly alkaline (pH 9.2); clear smooth boundary. (0 to 25 cm thick)
2Btn--36 to 53 cm; light gray (5Y 7/2) clay loam, olive (5Y 4/3) moist; moderate medium angular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine and fine roots; common very fine and fine tubular pores; common faint clay films on peds and in pores; strongly alkaline (pH 8.6); abrupt wavy boundary. (18 to 48 cm thick)
3C1--53 to 102 cm; light gray (5Y 7/2) very fine sand, olive (5Y 4/3) moist; massive; soft, very friable, nonsticky and nonplastic; few very fine and fine roots; common very fine interstitial pores; moderately alkaline (pH 8.0); clear smooth boundary. (41 to 61 cm thick)
3C2--102 to 132 cm; light gray (5Y 7/2) fine sandy loam, olive (5Y 4/3) moist; massive; soft, very friable, nonsticky and nonplastic; few very fine roots; few very fine tubular pores; moderately alkaline (pH 8.2); clear smooth boundary. (10 to 25 cm thick)
3C3--132 to 168 cm; light gray (5Y 7/2) loamy fine sand, olive gray (5Y 4/2) moist; massive; soft, very friable, nonsticky and nonplastic; few very fine roots, few very fine tubular pores; common medium faint pale yellow (5Y 7/4), and medium distinct olive (5Y 5/6) masses of iron accumulations lining pores and surrounding roots; moderately alkaline (pH 8.4).
TYPE LOCATION: Inyo County, California; about 4.2 miles northeast of Independence, 200 feet east of powerline; 1,880 feet west and 2,070 feet south of the NE corner of sec. 32, T. 12 S., R. 35 E.; USGS Independence 7.5 minute topographic quadrangle; longitude 118 degrees, 10 minutes, 13 seconds; latitude 36 degrees, 51 minutes, 50 seconds; WGS84 Decimal Degrees 36.8638889 latitude, -118.1702778 longitude.
RANGE IN CHARACTERISTICS: Thickness of the solum is 38 to 89 cm. The mean annual soil temperature is 15 to 17.8 degrees C. The soil temperature is 15 to 17.8 degrees C. The soil temperature is 8.3 degrees C or below from December 1 to March 1 and is seldom below 5 degrees C. The soil between the depths of 20 and 48 cm is moist in all parts for about 30 days in parts of January and February and is dry in all parts for 245 days from April 15 to December 15; aridic moisture regime bordering on xeric.
The A horizon is 10YR 6/2, 6/3, 7/2; 2.5Y 5/2, or 6/2. Moist color is 10YR 4/2, 4/3; 2.5Y 4/2 or 4/4. Textures are loamy fine sand, fine sandy loam or loam with 4 to 15 percent clay content in the upper part and loamy sand, loamy fine sand, sandy loam and fine sandy loam with 8 to 18 percent clay content in the lower part. It has 0 to 10 percent gravel. It is strongly effervescent or violently effervescent. Reaction is strongly alkaline or very strongly alkaline.
The 2BAtn horizon and 2Btn horizons are 10YR 6/2, 6/3, 6/4; 2.5Y 5/2, 6/2, 6/4, 7/2; 5Y 7/2 and 7/3. Moist color is 10YR 4/2, 4/3, 4/4; 2.5Y 4/2, 4/4; or 5Y 4/3. Textures are sandy loam, fine sandy loam, loam, clay loam, or sandy clay loam with 15 to 35 percent clay content while the particle size control section averages 18 to 30 percent clay content. It has 0 to 10 percent gravel. It is slightly effervescent to violently effervescent in the upper part and noneffervescent to strongly effervescent in the lower part. Reaction is strongly alkaline or very strongly alkaline. The electrical conductivity is 2.0 to 8.0 decisiemens/meter. Sodium absorption ratio is 13 to 60. Some pedons do not have a 2BAtn horizon.
The C horizon is 10YR 6/4, 7/3; 2.5Y 6/2, 7/2; 5Y 5/3, 6/2 or 7/2. Moist color is 10YR 4/6, 5/4; 2.5Y 4/2; 5Y 4/2, 4/3, 5/2 or 5/3. It is stratified lacustrine and/or stream sediments with textures ranging from loamy coarse sand to silty clay loam but averages loamy fine sand to fine sandy loam with 5 to 18 percent clay content. It has 0 to 15 percent gravel. It is noneffervescent or slightly effervescent. Reaction is mildly alkaline to strongly alkaline.
COMPETING SERIES: These are the
Cuyama and
Delano series. These soils are well drained and have a mean annual soil temperature that is over 17.8 degrees C. The soils also are mildly or moderately alkaline with a sodium-adsorption-ratio of less than 10 and an electrical conductivity of less than 2 millimhos per centimeter. They also do not have a water table within 6 feet. Cuyama soils also formed in stratified gravelly and cobbly terrace deposits with 10 to 30 percent cobbles.
GEOGRAPHIC SETTING: Pokonahbe soils are on stream and lacustrine terraces. Slopes are 0 to 5 percent. They formed in alluvium derived from mixed rock sources and lacustrine sediments. Elevations are 1,122 to 1,280 meters. The climate is arid with hot dry summers and cool, slightly moist winters. Mean annual precipitation is 100 to 150 mm. Mean January temperature is 3.9 degrees C; mean July temperature is 26.7 degrees C; mean annual temperature is 13.9 to 16.1 degrees C. Frost-free season is 140 to 225 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Eclipse (T),
Manzanar (T),
Mazourka (T),
Shondow (T), and
Winnedumah (T) soils. These soils are on stream terraces or lacustrine terraces of similar age. Eclipse soils are well drained and sandy. Mazourka soils are well drained and have the prismatic or columnar structure required for a natric horizon. Manzanar and Shondow soils are poorly drained. These soils are in the transitional area between MLRA 29 and 30. Winnedumah soils have 1 to 3 percent organic matter in the A horizon.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; moderately slow and slow permeability. The water table is at a depth of 100 to 150 cm from March 1 to June 1.
USE AND VEGETATION: Pokonahbe soils are used for rangeland, irrigated pasture, water spreading, and wildlife habitat. Vegetation in nonirrigated areas is alkali sacaton, black greasewood, rabbitbrush, inland saltgrass and shadscale saltbush.
DISTRIBUTION AND EXTENT: Owens Valley of eastern California. The series is not extensive in MLRA 29.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES PROPOSED: Benton-Owens Valley Area, Inyo County, California, 1989. Name from Paiute word for chief.
REMARKS: The Pokonahbe series would classify as a Natrargid if prismatic or columnar structure was present in the argillic horizon. Field observations have shown blocky structure to be typical in the argillic horizon. Diagnostic horizons and features recognized in the profile are:
1. Ochric epipedon--0 to 20 cm (A1, A2). Colors are too light for a mollic epipedon.
1.1 Organic carbon assumed less than 0.6 percent. (Based on nearby tests using Walkley-Black digestion method.
2. Argillic horizon--20 to 53 cm (2 BAtn and 2Btn horizons). Clay increase from 10 percent in A2 horizon to 18 percent in 2BAtn horizon to 30 percent in 2Btn horizon is from field estimate. Clay films were observed bridging mineral grains, on peds and in pores.
2.1 Medium subangular and angular blocky structure observed. Prismatic structure not evident.
3. Thermic temperature regime -- Mean annual soil temperature is 15 to 17.8 degrees C; this and other climatic characteristics are from available local climatic data and our preliminary data.
4. Mineralogy -- assumed mixed, no indication otherwise.
5. Particle size class -- fine-loamy based on hydrometer and field estimate of 20 to 53 cm control section.
6. Moisture regime - Aridic bordering on Xeric. It is based on vegetation indicators, depth to water table, and our preliminary temperature/moisture data.
6.1 Xeric subgroup -- Soil moisture control section is dry less than three fourths time that soil temperature at 50 cm is above 5 degrees C. Our temperature/moisture transect data indicates this subgroup about 67 percent of the time.
6.2 The moisture control section is dry throughout from April 15 to December 15. It is moist throughout from January 1 to February 1.
7. The soil temperature exceeds 5 degrees C, from February 1 to January 1 (335 days). Within this time period, the moisture control section is dry from May 1 to December 1 (215 days).
7.1 The soil temperature exceeds 8.3 degrees C from March 1 to December 1 (275 days). Within this time period, the moisture control section is dry from April 15 to December 1 (230 days).
National Cooperative Soil Survey
U.S.A.