LOCATION MERRILL CAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, thermic Aquic Calcixerolls
TYPICAL PEDON: Merrill silt loam - cultivated field (Colors are for dry soil unless otherwise noted.)
Ap1--0 to 6 inches; gray (5Y 5/1) silt loam, dark olive gray (5Y 3/2) moist; weak coarse subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; many very fine roots; many very fine interstitial pores; strongly effervescent; moderately alkaline (pH 8.0); clear smooth boundary. (4 to 6 inches thick)
Ap2--6 to 11 inches; gray (10YR 5/1) silt loam, very dark gray (10YR 3/1) moist; weak coarse subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common very fine roots; common very fine tubular pores; strongly effervescent; moderately alkaline (pH 8.0); clear smooth boundary. (2 to 5 inches thick)
A13--11 to 20 inches; gray (10YR 5/1) silt loam, very dark gray (10YR 3/1) moist; weak coarse angular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common very fine roots; common very fine tubular pores; strongly effervescent; moderately alkaline (pH 8.0); gradual wavy boundary. (7 to 9 inches thick)
A14--20 to 25 inches; gray (10YR 6/1) loam, dark gray (10YR 4/1) moist; weak coarse angular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common very fine roots; common very fine tubular pores; strongly effervescent; moderately alkaline (pH 8.0); gradual wavy boundary. (4 to 7 inches thick)
C1ca--25 to 31 inches; light gray (2.5Y 7/2) loam, grayish brown (2.5Y 5/2) moist; massive; slightly hard, friable, sticky, slightly plastic; few roots; few very fine tubular pores; 25 percent of the mass is large, irregularly shaped extremely hard lime concretions; violently effervescent; moderately alkaline (pH 8.0); gradual wavy boundary. (4 to 6 inches thick)
C2ca--31 to 43 inches; light gray (2.5Y 7/2) loam, grayish brown (2.5Y 5/2) moist; massive; slightly hard, friable, sticky, plastic; few very fine tubular pores; 50 percent of the mass is large, irregularly shaped extremely hard lime concretions; strongly effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (8 to 12 inches thick)
C3--43 to 50 inches; light brownish gray (2.5Y 6/2) loam, grayish brown (2.5Y 5/2) moist; massive; slightly hard, friable, slightly sticky, slightly plastic; few very fine tubular pores; strongly effervescent; moderately alkaline (pH 8.0); gradual wavy boundary. (6 to 10 inches thick)
C4--50 to 60 inches; light brownish gray (2.5Y 6/2) loam, grayish brown (2.5Y 5/2) moist; massive; slightly hard, friable, slightly sticky, slightly plastic; few very fine tubular pores; slightly effervescent; moderately alkaline (pH 8.0).
TYPE LOCATION: San Bernardino County, California; about 300 feet northwest of Eucalyptus and Central Avenue; SW1/4SE1/4SW1/4 of sec. 14, T.2S., R.8W.
RANGE IN CHARACTERISTICS: Depth to the horizon of maximum lime accumulation ranges from 20 to 40 inches. The mean annual soil temperature ranges from 59 degrees to 63 degrees F. The soil becomes moist in some part between depths of 4 and 12 inches about November 15 and remains moist until about May 20. Unless irrigated, it is dry the rest of the year under present drained conditions. The soil is moderately or strongly alkaline throughout. Dominant textures are silt loam or loam with about 20 to 30 percent clay in most horizons. The 10-to 40-inch control section has 6 to 20 percent sand coarser than very fine sand and averages 7 to 15 percent. It contains less than 1 percent rock fragments. The upper A horizons that have properties of a mollic epipedon are gray, dark gray, dark grayish brown or grayish brown in hue of 10YR, 2.5Y or 5Y, and are 13 to 20 inches thick. They have crumb to subangular blocky structure. The C horizon is gray, light gray or light brownish gray in hue of 10YR or 2.5Y. It has hard to extremely hard lime segregations.
COMPETING SERIES: These are the Bayshore, Castro, Domino, Patway, Sunnyvale, and Sunrise series. Bayshore soils have a seasonal water table above a depth of 25 inches and have fine-loamy control sections. Castro and Sunnyvale soils have more than 35 percent clay in the control section. Domino soils have an ochric epipedon. Patway soils have a mean annual soil temperature of less than 59 degrees F. and have coarse-loamy control sections. Sunrise soils have an ochric epipedon and an aridic moisture regime.
SETTING: Merrill soils are on nearly level flood plains at elevations of 500 to 2,400 feet. They formed in silty material from granitic sources. The climate is semiarid mesothermal with an average annual precipitation of 10 to 20 inches. The average annual temperature is 62 degrees to 65 degrees F.; average January temperature is 44 degrees to 52 degrees F., and average July temperature is 71 degrees to 80 degrees F. The freeze-free season is 230 to 280 days.
PRINCIPAL ASSOCIATED SOILS: These are the Chino, Grangeville, and Hilmar soils. Chino soils lack a calcic horizon and hard lime concretions. Grangeville soils are coarse-loamy and lack hard lime concretions. Hilmar soils are sandy over loamy and lack a calcic horizon.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; moderately slow to slow permeability. Improvement in drainage by pumping for irrigation has lowered the water table. Prior to drainage, these soils were saturated to within 25 or 35 inches of the surface in most years from January until July.
USE AND VEGETATION: These soils are used for irrigated pasture, forage crops, some truck crops, and grain. Natural vegetation is annual and perennial grasses and forbs.
DISTRIBUTION AND EXTENT: Merrill soils are inextensive and are in the intermediate valleys of southern California.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: San Bernardino County (Santa Ana River Watershed), California, 1940.
REMARKS: The Merrill soils would have been classed as Calcium Carbonate Solonchak soils.
OSED scanned by SSQA. Last revised by state on 9/72.