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<br /> :,an Joaquin County, California 45
<br /> precipitation is about 12 inches, the average annual air building foundations are constructed. Houses, roads,
<br /> temperature is about 60 degrees F, and the average and streets should be constructed above expected flood
<br /> �,Ost-free period is about 270 days. levels.
<br /> Typically, the surface layer is brown fine sandy loam This map unit is in capability units Ilw-3 (MLRA-17),
<br /> about 20 inches thick. The upper 28 inches of the irrigated, and IVw-3 (MLRA-17), nonirrigated. It is in
<br /> ,,nderlying material is grayish brown and light brownish vegetative soil group A.
<br /> gray, mottled fine sandy loam. The lower part to a depth
<br /> of 60 inches is dark gray, mottled clay. In some areas 134—Cometa sandy loam, 2 to 5 percent slopes.
<br /> ,�,e surface layer is loam. This moderately well drained, undulating soil is on low,
<br /> Included in this unit are small areas of Dello, dissected terraces. It is moderately deep to dense,
<br /> rangeville, and Merritt soils in landscape positions weakly cemented sediments. It formed in old alluvium
<br /> similar to those of the Columbia soil. Also included are derived from granitic rock sources. The vegetation in
<br /> s,all areas of Columbia soils that have coarse textured areas that have not been cultivated is mainly annual
<br /> wyers below the clayey substratum. Included areas grasses and forbs. Elevation is 100 to 300 feet. The
<br /> -lake up about 15 percent of the total acreage. average annual precipitation is about 16 inches, the
<br /> (Permeability is moderately rapid in the upper part of average annual air temperature is about 60 degrees F,
<br /> .ie Columbia soil and slow in the clayey substratum. and the average frost-free period is about 260 days.
<br /> Available water capacity is moderate. The effective Typically, the surface layer is brown sandy loam
<br /> ,t)oting depth of the crops commonly grown in the about 22 inches thick. The upper part of the subsoil is a
<br /> ,,u,unty is limited by an apparent water table that has claypan of brown sandy clay about 14 inches thick. The
<br /> ,,,een lowered to a depth of 3 to 5 feet through drainage lower part to a depth of 60 inches is brown, dense,
<br /> systems that require continual maintenance. The weakly cemented sandy loam and sandy clay loam. In
<br /> effective rooting depth also is limited by the clayey some areas the surface layer is coarse sandy loam.
<br /> substratum at a depth of 40 to 60 inches. Runoff is Included in this unit are small areas of Montpellier
<br /> ,iow, and the hazard of water erosion is slight. The rate soils in landscape positions similar to those of the
<br /> At water intake in irrigated areas is 1.5 inches per hour. Cometa soil and Redding soils on the slightly higher
<br /> -'he hazard of soil blowing is slight. The soil is subject parts of the landscape. Also included are small areas of
<br /> E.a rare flooding, which occurs during years of Rocklin and San Joaquin soils in the slightly lower
<br /> aonormally high precipitation. landscape positions and Cometa soils that have slopes
<br /> Most areas are used for irrigated crops. A few areas of 0 to 2 percent. Included areas make up about 15
<br /> are used for homesite development. This unit may percent of the total acreage.
<br /> .,rovide wetland functions and values. These should be Permeability is very slow in the Cometa soil.
<br /> oinsidered in plans for enhancement of wildlife habitat Available water capacity is moderate. The shrink-swell
<br /> ,r land use conversion. potential is high. The effective rooting depth is limited
<br /> This unit is suited to irrigated row and field crops. by the dense, weakly cemented sediments at a depth of
<br /> -he main limitations are the high water table and the 24 to 40 inches. Roots are restricted to cracks and the
<br /> iIayey substratum. Areas adjacent to levees are subject faces of peds in the claypan, which is at a depth of 17
<br /> c lateral seepage in wet years when the water level is to 25 inches. Depth to the water table is more than 6
<br /> "irgh. Careful applications of irrigation water are needed feet, but water may be briefly perched above the
<br /> o prevent the buildup of a high water table. Tile claypan or underlying sediments after periods of heavy
<br /> 1rainage can lower the water table if a suitable outlet is rainfall or irrigation. Runoff is slow, and the hazard of
<br /> available. Furrow, border, and sprinkler irrigation water erosion is slight. The rate of water intake in
<br /> systems are suitable. Maintaining crop residue on or irrigated areas is 1.5 inches per hour.
<br /> 'iear the surface helps to prevent excessive runoff, Most areas are used for livestock grazing or for
<br /> educes the hazard of soil blowing, and helps to dryland grain crops. A few areas are used for irrigated
<br /> maintain the rate of water intake and the organic matter orchards or vineyards or for homesite development.
<br /> ontent. This unit may provide wetland functions and values.
<br /> If this unit is used for homesite development, the These should be considered in plans for enhancement
<br /> rain limitations are the clayey spbstratum and the high of wildlife habitat or land use conversion.
<br /> ,,ater table. The rare flooding is a hazard. Septic tank Where this unit is used for livestock grazing, general
<br /> absorption fields do not function properly during rainy management considerations include saturated soil
<br /> periods because of wetness and slow permeability in conditions in concave areas following rainy periods. The
<br /> le substratum. A drainage system is needed if roads or characteristic plant community is mainly soft chess,
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