LOCATION MODA CAEstablished Series
TAXONOMIC CLASS: Fine, vermiculitic, thermic Abruptic Durixeralfs
TYPICAL PEDON: Moda loan, annual grass pasture. (Colors for dry conditions unless otherwise noted).
A11--0 to 1 inch; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; weak medium platy structure; slightly hard, friable, abundant very fine roots; common very fine pores; moderate organic matter content; slightly acid; abrupt, smooth boundary. (0 to 2 inches thick)
A12--1 to 7 inches; light brown (7.5YR 6/4) loam, brown (7.5YR 5/4) moist; massive breaking to fine subangular blocks; hard, friable, slightly sticky and slightly plastic; abundant very fine roots; very fine pores; low in organic matter; slightly acid; gradual, smooth boundary. (6 to 10 inches thick)
A3--7 to 14 inches; light brown (7.5YR 6/4) slightly heavier loam, dark brown (7.5YR 4/4) moist; massive but breaks to fine subangular blocks; hard, friable, slightly sticky and slightly plastic; abundant very fine roots; many very fine pores; slightly acid; abrupt, smooth boundary. (6 to 15 inches thick)
B2t--14 to 21 inches; brown (7.5YR 5/5) clay, strong brown (7.5YR 4/6) moist; weak coarse prismatic structure breaking to strong medium and coarse angular blocks; very hard, very firm, very sticky and plastic; plentiful very fine roots; many very fine interstitial and tubular pores; moderately thick, continuous clay films on all ped faces and in pores; much of colloid appears to be in bridges between mineral grains; slightly acid; abrupt, slightly wavy boundary. (2 to 8 inches thick)
C1m--21 to 30 inches; light yellowish brown (10YR 6/4) with coatings of brown indurated iron-silica hardpan, dark yellowish brown (10YR 4/4 coated with (7.5YR 4/4) moist; extremely hard dry or moist; roots spread out on top of horizon with little if any penetration; common very fine pores; moderately thick clay film in seams and pores; common dark metallic coatings in seams and fissures; somewhat less indurated in the lower portion; mildly alkaline; clear, wavy boundary. (2 to 18 inches thick)
C2--30 to 54 inches; light yellowish brown (10YR 6/4) clay loam, dark yellowish brown (10YR 4/4) moist; massive; very hard, firm to friable, sticky and plastic; no roots; few very fine pores; occasional clay film in pores; moderately alkaline, intermittently calcareous; very thick.
TYPE LOCATION: 5 1/2 miles ENE of Orland, 1/4 mile west of the intersection of Wyo Road and Fourth Avenue (SE cor. Section 9, T.22N, R.2W) in Glenn County,
California.
RANGE IN CHARACTERISTICS: Solum thickness is 14 to 35 inches to the bottom of the argillic horizon and mean annual soil temperature ranges from 63 to 66 degrees F. The soil is usually dry about the duripan during most summers.
The A horizon colors are in 10YR hues with values of 5, 6 and 7 and chromas of 3 and 4; and in 7.5YR hues with values of 5 and 6 and chromas of 4 and 6. Moist colors are dark brown or dark yellowish brown. Texture ranges from loam to gravelly loam; structure from weak to massive and reaction from slightly acid to medium acid. The Bt horizon colors are in 10YR hue with values of 4, 5 and 6 and chromas of 3 and 4; and in 7.5YR hue with values of 4, 5 and 6 and chromas of 4. Moist colors have higher chromas (1 or 2 units). Texture ranges from clay to gravelly clay; structure is moderate to strong prismatic, angular blocky or columnar; and reaction is slightly acid to moderately alkaline.
COMPETING SERIES: These include the Hillgate, Madera, Redding, San Joaquin and Yokohl soils. The Hillgate soils lack duripans, and the Madera soils have light yellowish brown A horizons and lack an abrupt AB boundary. The Redding soils are yellowish-red throughout the profile and are kaolinitic. The San Joaquin soils have colors in 5YR hue and have a gradual transition from A to Bt horizons. The Yokohl soils have colors in 5YR hues and have clay texture in the A horizons.
GEOGRAPHIC SETTING: The Moda soils occur on nearly level old terraces under annual grass and forb vegetation. The underlying alluvium was derived from a wide variety of rock formations. Elevations are 175 to 500 feet. The climate is Mediterranean with mean annual rainfall of 15 to 30 inches with hot dry summers and cool moist winters. Mean annual temperature is about 63 degrees F., average January temperature about 45 degrees F., and average July temperature about 83 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: The Moda soils occur in the same general areas as the Arbuckle, Corning, Hillgate, Perkins, Red Bluff and Redding soils.
DRAINAGE AND PERMEABILITY: Well drained, medium runoff, very slow permeability below the A horizon. The soil above the hardpan is saturated at times during the rainy season and while it is irrigated.
USE AND VEGETATION: Used for irrigated and dry pasture and for shallow rooted crops.
DISTRIBUTION AND EXTENT: West side of Sacramento Valley, California. The soils are inextensive
MLRA OFFICE RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Tehama County, California, August, 1962.
REMARKS: The Moda series was formerly classified in the Noncalcic Brown group. The current classification is based on an ochric epipedon, an argillic horizon with more than 35 percent clay, an abrupt AB boundary, and an indurated duripan.
OSED scanned by SSQA. Last revised by state on 2/66.