LOCATION ZENI CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, active, isomesic Ultic Haplustalfs
TYPICAL PEDON: Zeni loam - on a northeast facing convex slope of 25 percent under Douglas-fir, redwood, tanoak and huckleberry at 1,360 feet elevation. (Colors are for dry soil unless otherwise stated. When described April 18, 1978, the soil was moist throughout.)
Oi--1 inch to 0; partially decomposed litter of redwood, Douglas-fir and tanoak.
A--0 to 4 inches; pale brown (10YR 6/3) loam, dark brown (10YR 3/3) moist; moderate medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine, and few medium and coarse roots; many very fine tubular and interstitial pores; 2 percent (2 to 20 mm) soft, subangular pebbles; moderately acid (pH 5.7); clear wavy boundary. (4 to 9 inches thick)
BAt--4 to 16 inches; light brown (7.5YR 6/4) loam, brown (7.5YR 4/4) moist; moderate fine angular blocky structure; hard, firm, sticky and plastic; common fine and few medium and coarse roots; common very fine and fine tubular and interstitial pores; few thin clay films in pores and on peds; 1 percent (2 to 15 mm) nodules; moderately acid (pH 5.7); clear wavy boundary. (8 to 15 inches thick)
Bt--16 to 30 inches; yellow (10YR 7/6) loam, yellowish brown (10YR 5/6) moist; moderate fine and weak medium angular blocky structure; hard, firm, sticky and plastic; common coarse, and few fine and medium roots; many very fine tubular and interstitial pores; many thin (2.5YR 4/6) clay films and many thin (7.5YR 7/4) grainy coatings in pores and on peds; 10 percent (2 to 75 mm) soft, subangular pebbles; strongly acid (pH 5.4); abrupt irregular boundary. (8 to 20 inches thick)
Crt--30 to 45 inches; yellow (10YR 7/6) strongly weathered sandstone that crushes to sandy clay loam, yellowish brown (10YR 5/8) moist; fractures are 2 to 25 cm apart; few fine roots following fractures; continuous thick (2.5YR 4/6) clay films on fracture faces; strongly acid (pH 5.2); slakes in water.
TYPE LOCATION: Mendocino County, California; about 2 miles west from the town of Boonville on Mountain View Road; about 2,200 feet south and 1,350 feet east of the northwest corner of section 10, T.13 N., R.14 W., Boonville Quadrangle.
RANGE IN CHARACTERISTICS: Combined thickness of the A and Bt horizons and depth to a paralithic contact is 20 to 40 inches. The mean annual soil temperature ranges from 50 to 56 degrees F. The difference between mean summer and mean winter temperature ranges from 5 to 9 degrees F. The soil between depth of 6 and 17 inches is moist in all parts from November 1 to June 1 and is dry in some or all parts from July 1 to October 1 in most years. Base saturation (sum) ranges from 40 to 75 percent throughout the soil.
The A horizon is 10YR 4/3, 5/2, 5/3, 6/2, 6/3, 6/4; 7.5YR 7/4. Moist color is 10YR 2/2, 3/3, 3/4, 4/2, 4/3, 4/4; 7.5YR 5/6. Clay content ranges from 15 to 25 percent. Soft gravel content ranges from 0 to 10 percent. Where mollic colors occur the layer is too thin to meet the requirements for a mollic or umbric epipedon. Reaction is strongly through slightly acid.
The Bt horizon is 10YR 6/4, 6/6, 7/6; 7.5YR 6/4, 6/6, 7/4 or 7/6. Moist color is 10YR 4/6, 5/6; 7.5YR 3/4, 4/4, 4/6, 5/6, 6/4, 6/6, 6/8 or 7/6. It is loam, clay loam, sandy clay loam or gravelly clay loam. Clay content ranges from 20 to 35 percent. Soft gravel content ranges from 0 to 25 percent. Reaction is strongly or moderately acid.
The Cr horizon is soft highly weathered sandstone or mudstone that slakes in water. It becomes harder with increasing depth.
COMPETING SERIES: These are the Cabrillo (CA), Crispin (CA), Inverness (CA) and Ornbaun (CA) series. Crispin and Inverness soils have an umbric epipedon. Ornbaun soils are over 40 inches deep to a paralithic or lithic contact. Cabrillo soils are very deep.
GEOGRAPHIC SETTING: The Zeni soils occur on mountains. Slopes are 9 to 75 percent. Elevations are 200 to 2,500 feet. They formed in material weathered from sandstone or mudstone. The climate is humid with cool foggy summers and cool moist winters. A moderate coastal fog influence limits the diurnal and annual range of temperature. Mean annual precipitation ranges from 40 to 70 inches. Mean January temperature is about 50 degrees F; mean July temperature is about 60 degrees F; and the mean annual temperature is about 53 degrees F. The frost-free period is 220 to 320 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Ornbaun, and the Casabonne, Dehaven, Hotel, Irmulco, Kibesillah, Pardaloe, Tramway, Woodin, Wohly, and Yellowhound soils. Casabonne, Dehaven, Irmulco, Pardaloe and Yellowhound soils are more than 40 inches deep. Casabonne, Pardaloe, Woodin and Wohly soils have a xeric/mesic moisture-temperature regime. Dehaven, Hotel, Irmulco and Tramway soils have a udic moisture regime. Dehaven, Hotel, Irmulco, Kibesillah, Pardaloe, Woodin and Yellowhound soils have a loamy-skeletal control section.
DRAINAGE AND PERMEABILITY: Well drained; surface runoff under bare soil conditions is medium through very rapid; moderate permeability.
USE AND VEGETATION: This soil is used for timber production, wildlife habitat and watershed. Vegetation consists of Douglas-fir, redwood, tanoak, madrone and California huckleberry.
DISTRIBUTION AND EXTENT: Northern coastal California. The series is moderately extensive. MLRA 4.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Mendocino County, Eastern Part, California, 1985.
REMARKS: The activity class was added to the classification in March of 2003. Competing series were not checked at that time. - ET
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the layer from 0 to 4 inches (A horizon)
Argillic horizon - the zone from 16 to 30 inches Bt horizon
Paralithic contact - the boundary to weathered sandstone at 30 inches
Paralithic material has a similar AWC and bulk density to the overlying B horizons. Nodules are thought to be due to the effects of forest fires and are not present in all pedons.
ADDITIONAL DATA: Complete pedon data on modal site: NSSL S80-CA045-017, sample Nos. 80P2464-2468.