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<br /> L Soil Survey San Joaquin County, California
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<br /> minimizes crusting, and increases the rate of water. damage the crops. The hardpan limits the suitability for
<br /> intake. deep-rooted crops. Where feasible, deep ripping of this
<br /> This map unit is in capability units Ilw-2 (MLRA-17), restrictive layer can help to overcome this limitation.
<br /> irrigated, and IVw-2 (MLRA-17), nonirrigated. It is in The soil should be cultivated only within a narrow range
<br /> L vegetative soil group A. of moisture content. It is too sticky when wet and too
<br /> hard when dry. Furrow, border, and sprinkler irrigation
<br /> 173—Hollenbeck silty clay, 0 to 2 percent slopes. systems are suitable. Returning crop residue to the soil
<br /> ., This moderately well drained, nearly level soil is in or regularly adding other organic material improves
<br /> interfan basins. It is deep to a hardpan. It formed in fertility, minimizes crusting, and increases the rate of
<br /> alluvium derived from mixed rock sources. A few areas water intake.
<br /> ` are dissected by intermittent sloughs that have been This unit is suited to irrigated pasture. Irrigation water
<br /> filled as a result of land leveling. Elevation is 20 to 100 can be applied by sprinkler and border methods.
<br /> feet. The average annual precipitation is about 14 Leveling helps to ensure a uniform application of water.
<br /> inches, the average annual air temperature is about 60 Proper stocking rates, pasture rotation, and restricted
<br /> degrees F, and the average frost-free period is about grazing during wet periods help to keep the pasture in
<br /> 270 days. good condition and protect the soil from compaction.
<br /> Typically, the surface layer is grayish brown silty clay If this unit is used for homesite development, the
<br /> about 10 inches thick. The upper 27 inches of the main limitations are the high shrink-swell potential, the
<br /> subsoil is brown and yellowish brown clay. The next 5 slow permeability, and low strength. The rare flooding is
<br /> inches is grayish brown silty clay loam. The lower part a hazard. Properly designing foundations and footings
<br /> to a depth of 60 inches is a variegated light yellowish and diverting runoff away from buildings help to prevent
<br /> brown, weakly cemented to strongly cemented hardpan. the structural damage caused by shrinking and swelling.
<br /> In some areas the surface layer is clay or clay loam. On sites for septic tank absorption fields, the slow
<br /> Included in this unit are small areas of Archerdale, permeability can be overcome by increasing the size of
<br /> Cogna, and Vignolo soils on the slightly higher parts of the absorption field, backfilling the trench with sandy
<br /> the landscape, Stockton and Galt soils in landscape material, and installing long absorption lines. Properly
<br /> positions similar to those of the Hollenbeck soil, and designing buildings and roads can offset the limited
<br /> Guard soils in the slightly lower landscape positions. ability of the soil to support a load. Houses, roads, and
<br /> Also included are small areas of Hollenbeck soils that streets should be constructed above expected flood
<br /> are highly calcareous or saline-sodic throughout. levels.
<br /> .. Included areas make up about 15 percent of the total This map unit is in capability units IIs-5 (MLRA-17),
<br /> acreage. irrigated, and IVs-5 (MLRA-17), nonirrigated. It is in
<br /> Permeability is slow in the Hollenbeck soil. Available vegetative soil group C.
<br /> water capacity is moderate. The shrink-swell potential is
<br /> high. The effective rooting depth is limited by the 174—Hollenbeck clay, 1 to 3 percent slopes. This
<br /> hardpan at a depth of 40 to 60 inches. Depth to the moderately well drained, nearly level and gently sloping
<br /> water table is more than 6 feet, but water may be briefly soil is in interfan basins. It is deep to a hardpan. It
<br /> perched above the hardpan after periods of heavy formed in alluvium derived from mixed rock sources.
<br /> rainfall or irrigation. Runoff is slow, and the hazard of Slopes are plane and are incised by many shallow
<br /> water erosion is slight. The rate of water intake in meandering drainageways. The native vegetation is
<br /> ` irrigated areas is 0.1 inch per hour. The soil is subject annual grasses and (orbs. Elevation is 130 to 150 feet.
<br /> to rare flooding, which occurs during years of The average annual precipitation is about 17 inches,
<br /> abnormally high precipitation, the average annual air temperature is about 60 degrees
<br /> Most areas are used for irrigated crops or orchards. F. and the average frost-free period is about 270 days.
<br /> A few areas are used as irrigated pasture or for Typically, the surface layer is dark grayish brown and
<br /> homesite development. This unit may provide wetland brown clay about 32 inches thick. The upper 23 inches
<br /> functions and values. These should be considered in of the subsoil is dark grayish brown clay. The lower part
<br /> WW plans for enhancement of wildlife habitat or land use to a depth of 60 inches is a dark grayish brown,
<br /> conversion. strongly cemented hardpan. In some areas adjacent to
<br /> This unit is suited to irrigated row, field, and orchard drainageways, the surface layer is silty clay or fine
<br /> L crops. The main limitations are the slow permeability sandy loam.
<br /> and depth to the hardpan. Because of the restricted Included in this unit are small areas of Peters and
<br /> permeability, water applications should be regulated so Redding soils on the slightly higher parts of the
<br /> V that the water does not stand on the surface and landscape. Also included, in the lower positions, are
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