LOCATION SURNUF CAEstablished Series
TAXONOMIC CLASS: Fine, parasesquic, mesic Ultic Palexeralfs
TYPICAL PEDON: Surnuf loam - on a southwest facing convex slope of about 10 percent under Ponderosa pine, California black oak, poison oak and white leaf manzanita at 1870 feet elevation. (Colors are for dry soil unless otherwise stated. When described on August 26, l985, the soil was dry to 19 inches and slightly moist below.)
Oi--1 to 0 inches; partially decomposed needles, twigs and bark.
A--0 to 5 inches; reddish yellow (7.5YR 6/6) loam, strong brown (7.5YR 4/6) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine, fine and medium and few coarse roots; many very fine and common fine and medium tubular pores; 1 percent pebbles, l percent cobbles; moderately acid (pH 6.0), clear smooth boundary. (5 to 13 inches thick)
BAt--5 to 12 inches; reddish yellow (5YR 6/6) loam, yellowish red (5YR 4/6) moist; weak medium subangular blocky structure; slightly hard, very friable, sticky and plastic; common very fine, fine and medium and few coarse roots; many very fine and common fine and medium tubular pores; common cicadia burrows; few moderately thick clay films lining pores and common thin clay films bridging sand grains; 1 percent pebbles, l percent cobbles; moderately acid (pH 6.0); clear smooth boundary. (0 to 8 inches thick)
Bt1--12 to 19 inches; red (2.5YR 5/6) clay, red (2.5YR 4/6) moist; strong medium subangular blocky structure; hard, friable, sticky and plastic; common very fine and fine and few medium roots; common very fine tubular pores; common cicadia burrows; many moderately thick clay films on ped faces and few moderately thick clay films lining pores; 1 percent pebbles, l percent cobbles; moderately acid (pH 6.0); gradual smooth boundary. (6 to 9 inches thick)
Bt2--19 to 34 inches; red (2.5YR 4/8) clay loam, dark red (2.5YR 3/6) moist; strong medium subangular blocky structure; hard, friable, sticky and plastic; common very fine and fine and few medium roots; few very fine tubular pores; common cicadia burrows; many thick clay films on ped faces and few moderately thick clay films lining pores; 1 percent pebbles, l percent cobbles; 5 percent reddish yellow (7.5YR 7/8) soft rock fragments with many very fine and fine tubular pores and common thick clay films on rock surfaces; moderately acid (pH 5.8); gradual smooth boundary. (10 to 20 inches thick)
Bt3--34 to 54 inches; red (2.5YR 5/8) clay loam, red (2.5YR 4/8) moist; weak medium subangular blocky structure; hard, friable, sticky and plastic; few very fine, fine and medium roots; few very fine tubular pores; common cicadia burrows; many thick clay films on ped faces; 1 percent pebbles, l percent cobbles; 30 percent reddish yellow (7.5YR 7/8) soft rock fragments with many very fine and fine tubular pores and common thick clay films on rock surfaces; strongly acid (pH 5.5); gradual smooth boundary. (15 to 25 inches thick)
Bt4--54 to 66 inches; light red (2.5YR 6/8) clay loam, red (2.5YR 4/8) moist; weak medium subangular blocky structure; hard, friable, sticky and plastic; few very fine, fine and medium roots; few very fine tubular pores; common cicada burrows; few pressure faces; many thick clay films on ped faces; 1 percent pebbles, 1 percent cobbles; 50 percent reddish yellow (7.5YR 7/8) soft rock fragments with many very fine and fine tubular pores and common thick clay films on rock surfaces; strongly acid (pH 5.5); gradual smooth boundary. (10 to 15 inches thick)
BCt--66 to 77 inches; light red (2.5YR 6/8) clay loam, red (2.5YR 4/8) moist; massive; hard, friable, sticky and plastic; few very fine, fine and coarse roots; common very fine tubular pores; many thick clay films on ped faces; 1 percent pebbles, 1 percent cobbles; 50 percent reddish yellow (7.5YR 7/8) soft rock fragments with many very fine and fine tubular pores and common thick clay films on rock surfaces; strongly acid (pH 5.5).
TYPE LOCATION: Yuba County, California; about 1 mile north of Dobbins on Marysville Road, then about 1/4 mile north on Indiana Ranch Road, then west about 600 feet along dirt road, 700 feet east and 700 feet north of the southwest corner of section 29, T.18 N., R.7 E., MDBM, Challenge Quadrangle.
RANGE IN CHARACTERISTICS: Solum thickness is greater than 60 inches. The mean annual soil temperature ranges from 52 to 56 degrees F. The soil temperature is above 47 degrees F.
f.om March 1 to December 31. The 7 to 20 inch zone is dry in all parts from June 15 to October 31 and moist in all parts from November 15 to June 1. Base saturation ranges from 50 to 75 percent throughout.
The A horizon has dry color at 7.5YR 6/6; 5YR 6/4, 5/4 or 4/6 and moist color of 7.5YR 4/6; or 5YR 3/4. It is loam or cobbly loam with 18 to 27 percent clay. Coarse fragments range from 0 to 35 percent. Cobbles range from 0 to 20 percent. Gravel ranges from 0 to 15 percent. Reaction is medium to slightly acid.
The Bt horizon has dry color of 5YR 6/8, 6/6, 5/6, 4/6; 2.5YR 6/8, 5/8, 5/6, 4/6 or 3/6 and moist color of 5YR 5/6, 4/6, 3/6, 2.5YR 4/8, 4/6 or 3/6. It is clay loam, clay, cobbly clay loam or cobbly clay with 35 to 60 percent clay and the clay content does not decrease by as much as 20 percent of the maximum. Coarse fragments are typically in the upper Bt and range from 0 to 35 percent. Cobbles range from 0 to 20 percent. Gravel ranges from 0 to 15 percent. Reaction is medium to strongly acid.
COMPETING SERIES: This is the Forbes series. Forbes soils are neutral to moderately alkaline in the Bt horizon.
GEOGRAPHIC SETTING: The Surnuf soils are on hills and mountains and have slopes of 8 to 50 percent. The soils formed in materials weathered from intrusive basic igneous rocks, mainly gabbro diorite. Elevations are 1400 to 2800 feet. The climate is perhumid with warm, dry summers and cool, wet winters. The average annual precipitation is 35 to 50 inches. The average January temperature is 43 degrees F.; the average July temperature is 74 degrees F.; mean annual temperature is 55 to 59 degrees F. The frost-free season is 190 to 230 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Mildred and Sites soils. Mildred soils are in similar landscape positions and have a paralithic contact at 20 to 40 inches. Sites soils are in similar landscape positions and have base saturation less than 35 percent in the Bt horizon.
DRAINAGE AND PERMEABILITY: Well drained, low to high runoff; moderately slow permeability.
USE AND VEGETATION: Used mainly for timber production, homesite development, wildlife habitat and watersheds. Natural vegetation is ponderosa pine, California black oak and incense cedar with an understory of whiteleaf manzanita, Pacific poison oak, mountain misery and a few forbs and grasses.
DISTRIBUTION AND EXTENT: Northern part of the Sierra Nevada Range of California. The series is not extensive. MLRA is 22.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Yuba County, California, l992.
REMARKS: Surnuf soils were originally mapped as Dobbins series in the "Soils of the Yuba Area". University of California, Davis, and Yuba County. l969.
10/2006 changed runoff terminology.
ADDITIONAL DATA: Sampled as reference sample No. S85CA-115-9 by NSSL. Also sampled by University of California, Davis, in l967.