LOCATION LUPOYOMA CAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, thermic Cumulic Ultic Haploxerolls
TYPICAL PEDON: Lupoyoma silt loam--on a southwest facing linear slope of 1 percent under forbs and annual grasses at 1,350 feet. (Colors are for dry soil unless otherwise stated. When described on July 7, 1978, the soil was dry to 5 inches and moist below.)
Ap1--0 to 5 inches; brown (10YR 5/3) silt loam, very dark grayish brown (10YR 3/2) moist; moderate fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many very fine and common fine and medium roots; many very fine and fine interstitial and few very fine tubular pores; slightly acid (pH 6.1); clear smooth boundary. (2 to 9 inches thick)
Ap2--5 to 12 inches; brown (10YR 5/3) silt loam, very dark grayish brown (10YR 3/2) moist; weak coarse prismatic structure parting to coarse subangular blocky; hard, friable, slightly sticky and slightly plastic; many very fine and common fine and medium roots; common very fine and fine interstitial and many very fine and few fine tubular pores; slightly acid (pH 6.1); clear smooth boundary. (4 to 12 inches thick)
A1--12 to 20 inches; brown (10YR 5/3) silt loam, dark brown (10YR 3/3) moist; weak fine and medium prismatic structure parting to fine subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; many very fine, common fine and few medium roots; common very fine and fine interstitial and many very fine and few fine tubular pores; slightly acid (pH 6.2); clear smooth boundary. (0 to 15 inches thick)
A2--20 to 31 inches; brown (10YR 5/3) silt loam, dark brown (10YR 3/3) moist; weak fine and medium prismatic structure parting to weak fine subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; many very fine and few fine roots; common fine interstitial and many very fine and common fine tubular pores; slightly acid (pH 6.4); clear smooth boundary. (0 to 11 inches thick)
AC--31 to 42 inches; brown (10YR 5/3) silt loam, very dark grayish brown (10YR 3/2) moist; few very fine faint light brownish gray (2.5Y 6/2) mottles; dark grayish brown (2.5Y 4/2) moist; weak fine prismatic structure parting to weak fine subangular blocky; slightly hard, friable, sticky and slightly plastic; common very fine and few fine roots; few very fine interstitial and common very fine and few fine tubular pores; neutral (pH 6.6), clear smooth boundary. (7 to 11 inches thick)
C1--42 to 49 inches; mixed brown (10YR 5/3) and very dark grayish brown (10YR 3/2) silt loam, dark grayish brown (10YR 4/2) rubbed moist; few fine and medium distinct light brownish gray (2.5Y 6/2) mottles; dark grayish brown (2.5Y 4/2) moist; weak fine and medium prismatic structure parting to weak fine subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; few very fine and fine roots; few fine tubular pores; neutral (pH 6.8) clear smooth boundary. (5 to 20 inches thick)
C2--49 to 84 inches; mixed brown (10YR 5/3) and very dark grayish brown (10YR 3/2) silt loam, dark grayish brown (10YR 4/2) rubbed moist; few fine and medium distinct light brownish gray (2.5Y 6/2) mottles; dark grayish brown (2.5Y 4/2) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; common very fine interstitial and many very fine and fine tubular pores; slightly alkaline (pH 7.7).
TYPE LOCATION: Lake County, California; 150 feet west of Elk Mountain Road, at a point about 0.2 miles north of it's intersection with Highway 20; 1,100 feet south and 140 feet west of the northeast corner of sec. 12, T. 15 N., R. 10 W.; Upper Lake quadrangle.
RANGE IN CHARACTERISTICS: The soils are dry between depths of 6 and 18 inches from June 1 to October 15, unless irrigated, and usually are moist from January 1 to April 15. Depth to mottles ranges from 20 to 36 inches. Mean annual soil temperature varies from 59 degrees to 61 degrees F. The A horizon has 1 to 2 percent organic carbon that decreases irregularly with depth and is 20 to 30 inches thick. The base saturation in the upper 75 cm is less than 75 percent. The soil ranges from 18 to 35 percent clay with less than 15 percent fine sand or coarser materials between a depth of 10 to 40 inches. The soil has up to 1 percent charcoal particles 1 to 10 mm in diameter.
The A horizon is 10YR 5/3 or 5/2. Moist color is 10YR 3/3 or 3/2. It is silt loam, loam or very fine sandy loam. It is moderately acid through neutral.
The C horizon is 10YR 6/4, 6/3, 6/2, 5/3, 4/3, 4/2 or 2.5Y 6/2. Moist color is 7.5YR 4/6, 4/4; 10YR 4/2, 3/3, 3/2, 3/1, or 2.5Y 4/2. It is very fine sandy loam, loam, silt loam, or silty clay loam. Lenses of fine sandy loam or sandy loam also occur in this horizon below 40 inches. This horizon is massive or has weak subangular blocky or prismatic structure. It is slightly acid through slightly alkaline.
COMPETING SERIES: These are the Mocho, and Suey series in other families. Mocho soils have a fine-loamy particle-size class, and greater than 75 percent base saturation. Suey soils have a base saturation of greater than 75 percent in the upper 75 cm of the soil profile, and have a regular decrease in organic carbon with increasing depth.
GEOGRAPHIC SETTING: Lupoyoma soils are on floodplains that are mostly protected by dikes and levees. These soils are formed in alluvium weathered from mixed rock sources, dominantly sandstone and shale. Elevations are 800 to 1,450 feet. The climate is subhumid with warm dry summers and cool moist winters. Mean annual precipitation is 25 to 40 inches. The mean January temperature is 42 degrees F; the mean July temperature is 68 degrees F; and mean the mean annual temperature is 55 to 59 degrees F. Frost-free season is 150 to 205 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arroyo Seco, Eachus and Neice soils. Arroyo Seco soils are coarse-loamy and have a mollic epipedon less than 20 inches thick. Eachus soils have clayey control sections and Neice soils have clayey-skeletal control sections, and both are on mountains.
DRAINAGE AND PERMEABILITY: Moderately well drained; very slow runoff, moderately slow permeability. Unprotected areas are subject to rare flooding.
USE AND VEGETATION: Used mainly for pear, walnut, and wine grape production and for irrigated pasture. Native vegetation is scattered valley oak with an understory of soft chess and wild oats.
DISTRIBUTION AND EXTENT: Valleys of the Coast Range of Northern California. The soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Lake County, California 1983.
REMARKS: Lab sampled 9/79 for organic carbon and base saturation. Lab sample numbers from Lincoln Lab (7822598-2603).
Organic carbon in the mollic epipedon (0 to 31 inches) ranged from 1.08 to 2.10 percent. Below 31 inches the O.C. decreased irregularly with depth. Base saturation (by sum of cations) in the A1 and A2 horizons was 69 percent. The proposed classification of Cumulic Ultic Haploxeroll is a change from the former classification of Mollic Xerofluvent.
The activity class was added to the classification in February of 2003. Competing series were not checked at that time. - ET