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<br /> San Joaquin County, California 107
<br /> indicate a somewhat poorly drained soil; however, adding other organic material improves fertility,
<br /> drainage has been improved by levees and reclamation minimizes crusting, and increases the rate of water
<br /> projects. Typically, the surface layer and the upper part intake.
<br /> of the subsoil are gray, mottled clay loam about 16 The Rioblancho soil is in capability units Illw-8
<br /> inches thick. The next 12 inches of the subsoil is (MLRA-17), irrigated, and IVw-8 (MLRA-17),
<br /> variegated light gray and very pale brown, mottled clay nonirrigated. It is in vegetative soil group G. The Urban
<br /> loam. The next 11 inches is variegated very pale brown land is not assigned a capability classification or a
<br /> and light yellowish brown, mottled sandy loam. The vegetative soil group.
<br /> mower part to a depth of 80 inches is a variegated light
<br /> gray and light yellowish brown, strongly cemented 228—Rocklin sandy loam, 2 to 5 percent slopes.
<br /> hardpan. The soil is calcareous below a depth of 7 This moderately well drained, undulating soil is on
<br /> inches. In some areas the surface layer is loam. dissected terraces. It is moderately deep to a hardpan.
<br /> Permeability is moderately slow in the Rioblancho It formed in old alluvium derived from granitic rock
<br /> soil. Available water capacity is moderate. The effective sources. The native vegetation is mainly annual
<br /> rooting depth is limited by the hardpan at a depth of 20 grasses, forbs, and scattered California white oak.
<br /> to 40 inches. The water table has been lowered to a Slopes occur as a complex of plane and convex side
<br /> depth of more than 6 feet through drainage systems slopes and concave drainageways. Elevation is 80 to
<br /> that require continual maintenance, but water may be 300 feet. The average annual precipitation is about 16
<br /> perched above the hardpan after periods of heavy inches, the average annual air temperature is about 61
<br /> rainfall or irrigation. Runoff is slow, and the hazard of degrees F, and the average frost-free period is about
<br /> water erosion is slight. The rate of water intake in 275 days.
<br /> urrigated areas is 0.5 inch per hour. The soil is subject Typically, the surface layer and the upper part of the
<br /> to rare flooding, which occurs during years of subsoil are pale brown and light brown sandy loam
<br /> abnormally high precipitation. about 25 inches thick. The next 11 inches of the subsoil
<br /> Urban land consists of areas covered by roads, is light brown sandy clay loam. The lower part is a light
<br /> driveways, sidewalks, parking lots, buildings, and other brown, indurated hardpan about 4 inches thick. The
<br /> structures. The soil material under the impervious underlying material to a depth of 60 inches is reddish
<br /> surface is similar to that of Rioblancho clay loam. yellow, dense, weakly cemented sandy loam. In some
<br /> Most areas are used for urban development. A few areas the surface layer is loam.
<br /> areas are used for irrigated crops. This unit may Included in this unit are small areas of Cometa,
<br /> orovide wetland functions and values. These should be Montpellier, and Redding soils on the slightly higher
<br /> considered in plans for enhancement of wildlife habitat terraces, San Joaquin soils on the slightly lower
<br /> or land use conversion. terraces, and moderately coarse textured soils that
<br /> Where the Rioblancho soil is used for urban have a hardpan at a depth of less than 20 inches and
<br /> development, the main limitations are depth to the are in landscape positions similar to those of the
<br /> hardpan, the moderately slow permeability, and low Rocklin soil. Also included are small areas of Rocklin
<br /> strength. The rare flooding is a hazard. Ripping the soils that have slopes of 0 to 2 percent or 5 to 15
<br /> hardpan improves permeability and thus also improves percent. The areas where slopes are 0 to 2 percent are
<br /> the suitability of the soil for septic tank absorption fields. on toe slopes, and the areas where slopes are 5 to 15
<br /> The moderately slow permeability can be overcome by percent are on narrow embankments. Included areas
<br /> increasing the size of the absorption field. Properly make up about 15 percent of the total acreage.
<br /> designing buildings and roads can offset the limited Permeability is moderate in the Rocklin soil. Available
<br /> ability of the soil to support a load. Houses, roads, and water capacity is low. The effective rooting depth is
<br /> streets should be constructed above expected flood limited by the hardpan at a depth of 20 to 40 inches.
<br /> levels. Water is briefly perched above the hardpan after
<br /> The Rioblancho soil is suited to irrigated row and periods of heavy rainfall or irrigation. Runoff is slow or
<br /> field crops. The main limitation is depth to the hardpan, medium, and the hazard of water erosion is slight or
<br /> Which limits the suitability for deep-rooted plants. Where moderate. The rate of water intake in irrigated areas is
<br /> feasible, deep ripping of this restrictive layer can help to 1.5 inches per hour.
<br /> 3vercome this limitation. Careful applications of Most areas of this unit are used for livestock grazing
<br /> "lation water are needed to prevent the buildup of a or dryland grain crops. A few areas are used for
<br /> nigh water table. A drainage system may be needed. irrigated vineyards, irrigated pasture, or homesite
<br /> Burrow, border, and sprinkler irrigation systems are development.
<br /> suitable. Returning crop residue to the soil or regularly Where this unit is used for livestock grazing, general
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