LOCATION CORNING CAEstablished Series
TAXONOMIC CLASS: Fine, mixed, active, thermic Typic Palexeralfs
TYPICAL PEDON: Corning gravelly loam - on a 2 percent slope under annual grasses and forbs at an elevation of 270 feet. When described April 5, 1945, the soil was moist throughout. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 8 inches; yellowish red (5YR 5/6) gravelly loam, yellowish red (5YR 4/6) moist; weak fine granular structure; hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine pores; strongly acid (pH 5.5); gradual smooth boundary. (4 to 9 inches thick)
A1--8 to 15 inches; yellowish red (5YR 5/6) gravelly loam, dark red (2.5YR 4/6) moist; weak fine and medium angular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine pores; moderately acid (pH 5.8); abrupt smooth boundary. (5 to 10 inches thick)
A2--15 to 21 inches; yellowish red (5YR 5/6) gravelly loam, dark red (2.5YR 4/6) moist; weak fine and medium angular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine pores; strongly acid (pH 5.4); abrupt wavy boundary. (5 to 8 inches thick)
Bt1--21 to 29 inches; red (2.5YR 5/6) gravelly clay, dark red (2.5YR 4/6) moist; strong coarse angular blocky structure that separates readily to very fine subangular blocky on drying; extremely hard, extremely firm, sticky and very plastic; few very fine roots; common very fine tubular pores; continuous moderately thick clay films on faces of peds and lining pores but most are as bridges; strongly acid (pH 5.2); clear wavy boundary. (5 to 15 inches thick)
Bt2--29 to 36 inches; yellowish red (5YR 5/6) gravelly clay loam, dark red (2.5YR 4/6) moist; weak coarse angular blocky structure; very hard, very firm, sticky and plastic; few very fine roots; common very fine pores; continuous moderately thick clay films lining pores and on a few faces of peds, strongly acid (pH 5.2); clear wavy boundary. (4 to 10 inches thick)
C--36 to 60 inches; yellowish red (5YR 5/6) gravelly stratified sandy clay loam, red (2.5YR 4/6) moist; massive; hard, firm, slightly sticky and plastic; few very fine roots; common very fine pores; continuous thin clay films lining pores, moderately thick along cleavage planes; strongly acid (pH 5.2); diffuse smooth boundary.
TYPE LOCATION: Tehama County, California; about 3 miles south of Corning and 0.6 mile north of the SW corner of section 22, T.23 N., R.3W., just east of old US Highway 99W.
RANGE IN CHARACTERISTICS: Solum thickness is 23 to 60 inches. Soil temperature is greater than 47 degrees F throughout the year. Mean annual soil temperature is 60 to 67 degrees F at 20 inches. Solum thickness differs over short distances because of hummocky microrelief.
The soil between depths of 7 and 20 inches is usually moist in some part from about late October until late May and is continuously dry the rest of the time. Weighted average clay content of the upper 20 inches of the argillic horizon is 35 to 55 percent.
The A horizon is 7.5YR 4/4, 4/6, 5/4, 5/6, 6/4, 6/6; 5YR 3/4, 4/4, 4/6, 5/3, 5/4, 5/6, 6/3, 6/4, 6/6; 2.5YR 4/6, 5/4, 5/6, 6/4, 6/6, 10YR 5/6, 5/4, and 5/3. Moist color is 10YR 4/4, 3/4, and 3/3 and 7.5YR 4/4, 3/3, 3/4; 5YR 3/4, 3/6, 4/4, 4/6; 2.5YR 3/4, 3/6, 4/4. In the concave intermound, the upper 2 to 9 inches of the A horizon has dry color of 10YR 5/3, 5/4, 5/6, 6/3, 6/4; 7.5YR 5/4, 4/4 and moist color is 10YR 3/3, 4/3, 3/4, 4/4; 7.5YR 3/4, 4/4. Texture is clay loam, sandy clay loam, loam, sandy loam or fine sandy loam or their gravelly or cobbly equivalents. Content of coarse fragments is 0 to 35 percent. In some pedons organic matter content is greater than 1 percent in the upper 1 to 3 inches but in all pedons it decreases to less than 1 percent below this depth. Reaction is strongly acid to neutral. Base saturation by sum of cations is 35 to 75 percent.
Pedons in which the depth to the 2Bt horizon is greater than 20 inches have a BA horizon. Color is similar to the A horizon color on the mound. Texture, reaction and base saturation are similar to the A horizon. Clay content is 1 to 4 percent higher and increases within a vertical distance of greater than 12 inches.
The Bt horizon is 7.5YR 5/6, 4/6; 5YR 3/3, 3/4, 4/4, 4/6, 5/4, 5/6, 5/8, 6/6; 2.5YR 3/4, 3/6, 4/6, or 5/6. Moist color is 7.5YR 4/6; 5YR 3/4, 4/4, 5/6, 4/6; 2.5YR 3/4, 3/6, 4/6. The lower part of the horizon has hue of 7.5YR in some pedons. Texture is clay loam or clay or their gravelly equivalents with 35 to 55 percent clay in the upper part and clay, sandy clay loam or clay loam or their gravelly equivalents in the lower part. Content of coarse fragments is 5 to 35 percent with 0 to 15 percent cobbles. Increase in clay content at the upper boundary is 15 to 40 percent within 1 inch. Reaction is very strongly acid to slightly acid in the upper part and strongly acid to neutral in the lower part. Base saturation is 75 to 95 percent.
The C horizons are generally stratified. Texture is loamy coarse sand to clay loam or their gravelly or very gravelly equivalents with 10 to 30 percent clay. Content of coarse fragments is 5 to 50 percent with 0 to 15 percent cobbles. Reaction is strongly acid to slightly alkaline. In some pedons this horizon has discontinuous weak cementation.
COMPETING SERIES: These are the Cometa, Hytop, Millsap, Orognen and Yokayo series. Cometa soils have greater than 75 percent base saturation in some or all parts of the A horizon. Millsap soils have a lithic contact at 20 to 40 inches. Orognen soils have a soil temperature below 47 degrees from January 1 to February 15 and a frost free season of 190 to 240 days. Yokayo soils have 10YR or 2.5Y hues in the Bt horizon. Hytop soils have a paralithic contact at 20 to 40 inches.
GEOGRAPHIC SETTING: Corning soils are on nearly level to gently rolling high terraces and terrace remnants with mound, intermound microrelief and rolling to hilly sideslopes of terraces. Elevations are 75 to 1,300 feet. Slopes are 0 to 30 percent. The soils formed in gravelly alluvium derived from mixed rock sources. Climate is subhumid with hot dry summers and cool moist winters. Mean annual precipitation is 14 to 30 inches. Mean annual temperature is about 58 to 62 degrees F, average January temperature is about 45 degrees F and average July temperature is 77 to 82 degrees F. The frost-free period is 185 to 290 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Altamont and Red Bluff soils and the similar Hillgate, Newville, Redding and San Ysidro soils. Altamont soils have slickensides and occur on hills underlain by shale. Red Bluff soils have kaolinitic mineralogy.
DRAINAGE AND PERMEABILITY: Well drained on the mound and in areas that lack hummocky microrelief; moderately well drained in the intermound; low to very high runoff on the mound, ponded to slow in the intermound; very slow and slow permeability.
USE AND VEGETATION: Used for annual livestock grazing, dryland grains and irrigated pasture. Vegetation consists of soft chess, wildoats, mouse barley and filaree. Toad rush and bee thistle also occur in the intermound.
DISTRIBUTION AND EXTENT: High terraces in the Sacramento and San Joaquin Valleys in California. The series is of large extent in MLRA- 17. It has been used in the past in MLRA 14 and 15.
MLRA OFFICE RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Tehama County (Red Bluff area), California, 1910.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the surface to a depth of 21 inches (Ap, A1, A2)
Argillic horizon - the zone from 21 to 36 inches (Bt1, Bt2)
ADDITIONAL DATA: This pedon sampled as S45CA-057-014 in SSIR NO. 24. Other pedons in Sacramento Co. sampled for complete characterization by Lincoln NE NSSL in 1979; pedon numbers are S79CA-067-002 and S79CA-067- 003 for the mound and intermound, respectively. Taxadjunct sampled in Glenn County: NSSl Pedon S45CA-021-012. Also Pedon S45CA-021-013 in Glenn County, CA and S45CA-103-014 in Tehama County.