LOCATION WAPPO CA
Established Series
Rev. CAK/DWS/DJE
01/2023
WAPPO SERIES
The Wappo series consists of very deep, moderately well drained soils formed in alluvium from mixed rock sources. These soils are on alluvial terraces and have slopes of 2 to 15 percent. The mean annual precipitation is about 30 inches and the mean annual temperature is about 57 degrees F.
TAXONOMIC CLASS: Fine, smectitic, thermic Mollic Palexeralfs
TYPICAL PEDON: Wappo loam--on a northwest facing convex knoll of 5 percent in a walnut orchard at an elevation of 1,400 feet. (Colors are for dry soil unless otherwise stated. When described on 11/10/76 the soil was dry to 7 inches and moist below.)
Ap--0 to 4 inches; brown (7.5YR 5/4) loam, dark brown (7.5YR 3/4) moist; moderate fine and medium subangular blocky structure parting to moderate fine, medium, and coarse granular; hard, roots; many very fine interstitial and common very fine tubular pores; 2 percent pebbles 2 to 10mm in diameter; moderately acid (pH 5.7); abrupt wavy boundary. (2 to 6 inches thick)
BAt--4 to 10 inches; brown (7.5YR 5/4) loam, dark brown (7.5YR 3/4) moist; moderate medium and coarse subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine tubular pores; few thin clay films on peds, in pores and bridging mineral grains; 2 percent pebbles 2 to 10 mm in diameter; moderately acid (pH 6.0); abrupt wavy boundary. (6 to 12 mm thick)
Bt1--10 to 34 inches; strong brown (7.5YR 5/6) clay, brown (7.5YR 5/4) moist; strong medium, coarse and very coarse prismatic structure; very hard, firm, sticky and plastic; few very fine roots; many very fine tubular pores; few pressure faces, slightly acid (pH 6.5); clear wavy boundary. (12 to 24 inches thick)
Bt2--34 to 42 inches; reddish yellow (7.5YR 6/6) clay loam, brown (7.5YR 4/4) moist; common fine and medium distinct yellowish red (5YR 4/6) mottles; weak coarse and very coarse prismatic structure; very hard, firm, sticky and plastic; few very fine roots; few very fine tubular pores; common thin and few moderately thick clay films on peds and in pores; common pressure faces; 5 percent pebbles 2 to 20 mm in diameter; neutral (pH 6.7); clear wavy boundary. (8 to 15 inches thick)
2BC--42 to 51 inches; reddish yellow (7.5YR 6/6) sandy clay loam, brown (7.5YR 4/4) moist; common fine and medium distinct yellowish red (5YR 4/6) mottles; weak fine, medium and coarse angular blocky structure; hard, firm, sticky and plastic; few very fine tubular pores; common pressure faces; 10 percent pebbles 2 to 25 mm in diameter; neutral (pH 7.3); clear wavy boundary. (0 to 10 inches thick)
3C--51 to 63 inches; light yellowish brown (10YR 6/4) clay loam, brown (10YR 5/3) moist; common fine distinct yellowish red (5YR 4/6) mottles; massive; very hard, firm, sticky and plastic; few very fine tubular pores; moderately alkaline (pH 8.0)
TYPE LOCATION: Lake County, California; approximately 2,400 feet west of Big Valley Road on Voigt Road, then approximately 1,200 feet south into walnut orchard; approximately 1,300 feet south and 2,400 feet west of the northeast corner of Sec. 18, T. 13N, R. 9 W.
RANGE IN CHARACTERISTICS: Thickness of the solum is 40 to 60 inches and depth of the soil is greater than 60 inches. The mean annual soil temperature is 59 degrees to 62 degrees F. The soil between the depths of 6 to 20 inches is dry in all parts from June 15 to October 15, and is moist in all parts from January 1 to April 15. The particle-size control section averages 35 to 55 percent clay content. Base saturation (sum of cations) is 60 to 90 percent throughout, and is 75 percent or more in at least some part of the argillic horizon. Reaction is medium acid to neutral throughout the A horizon and B horizon and neutral to moderately alkaline in the C horizon.
The A horizon is 7.5YR 5/4, 6/4; 10YR 6/4, or 7/4. Moist color is 7.5YR 3/4, 4/4; 10YR 3/4, or 4/3. Moist value of 3 occurs throughout the upper 4 to 6 inches.
The Bt horizon is 7.5YR 5/4, 5/6, 6/4, 6/6; or 10YR 6/4. Moist colors are 7.5YR 4/4, 5/4, 5/6; or 10YR 6/3. It is clay loam or clay with 35 to 55 percent clay. It contains 0 to 15 percent gravel. Some pedons lack an BC horizon.
The C horizon is 7.5YR 6/4, 6/6; or 10YR 6/4. Moist colors are 7.5YR 5/4, 5/6; 10YR 6/3 or 5/3. It is clay loam or clay with 0 to 15 percent gravel.
COMPETING SERIES: These are the
Kimball,
Milpitas,
Newville,
Positas and
Tierra series Kimball soils have hues pf 2.5YR and 5YR in the Bt horizon. Milpitas, Postas and Tierra soils have an E horizon. Newville soils have a MAST of 62 degrees to 65 degrees F, have 15 to 35 percent gravel in the A and B horizons and more than 50 percent in the Bc horizon; and FFS is 250 to 280 days.
GEOGRAPHIC SETTING: Wappo soils are on alluvial terraces. Slopes are 2 to 15 percent. The soils formed in alluvium derived from mixed sources. Elevations are 1,400 to 1,650 feet. The climate is subhumid with warm, dry summers and cool, moist winters. The average annual precipitation is 25 to 35 inches. Mean January temperature is 43 degrees F; mean July temperature is 68 degrees F; mean annual temperature is 55 degrees to 59 degrees F. Frost-free season is 160 to 205 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Bally,
Manzanita,
Phipps, and
Redvine soils. Bally soils are clayey-skeletal and occur on uplifted sediments. Manzanita soils are fine-loamy. Phipps soils have a gradual clay increase and occur on uplifted sediments. Redvine soils have mixed mineralogy.
DRAINAGE AND PERMEABILITY: Moderately well drained; medium runoff; very slow permeability.
USE AND VEGETATION: This soils is used mainly for rangeland, vine-yards, hay and pasture, and homesite development. The native vegetation is annual grasses and forbs and scattered blue oaks.
DISTRIBUTION AND EXTENT: In the Clear Lake basin in Lake County, California. The series is not extensive.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Lake County, California 1983.
REMARKS:
OSED scanned by SSQA. Last revised by state on 3/84.
National Cooperative Soil Survey
U.S.A.