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Si Joaquin County, California
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<br /> ally ,ium derived from granitic rock sources. Mottles in irrigated, and IVw-2 (MLRA-16), nonirrigated. It is in
<br /> th )rofile indicate a poorly drained soil; however, vegetative soil group H.
<br /> dr—cage has been improved by levees and reclamation
<br /> projects. Elevation is 15 feet below sea level to 5 feet 180—Jacktone clay, 0 to 2 percent slopes. This
<br /> at re. The average annual precipitation is about 14 somewhat poorly drained, nearly level soil is in basins.
<br /> in, es, the average annual air temperature is about 60 It is moderately deep to a hardpan. It formed in alluvium
<br /> degrees F, and the average frost-free period is about derived from mixed rock sources. Mottles in the profile
<br /> 27 days. indicate a somewhat poorly drained soil; however,
<br /> ypically, the surface layer is light brownish gray silty drainage has been improved by levees and reclamation
<br /> clay loam about 15 inches thick. Below this is a buried projects. A few areas are dissected by intermittent
<br /> SU'lace layer of grayish brown, mottled silty clay loam sloughs that have been filled as a result of land
<br /> at it 19 inches thick. The underlying material to a leveling. Elevation is 5 to 100 feet. The average annual
<br /> dep,h of 60 inches is stratified, grayish brown, mottled precipitation is about 14 inches, the average annual air
<br /> siltv clay loam. In some areas the surface layer is silt temperature is about 60 degrees F, and the average
<br /> to i or mucky loam. frost-free period is about 270 days.
<br /> cluded in this unit are small areas of Dello, Kingile, Typically, the surface layer is very dark gray and
<br /> Ryde, and Valdez soils in landscape positions similar to dark gray clay about 22 inches thick. The upper 12
<br /> th, e of the Itano soil. Included areas make up about inches of the subsoil is dark gray clay and light gray
<br /> 1E ercent of the total acreage. clay loam. The next 3 inches is a light gray, strongly
<br /> Permeability is moderately slow in the Itano soil. cemented to indurated hardpan. The next 9 inches is
<br /> A\•-'lable water capacity is very high. The effective yellowish brown loam. The lower part to a depth of 60
<br /> ,o ng depth of the crops commonly grown in the inches is a yellowish brown, weakly cemented hardpan.
<br /> ,ounty is limited by an apparent water table that is In some areas the surface layer is silty clay or silty clay
<br /> 'eaulated at a depth of 3.0 to 4.5 feet by pumping. loam.
<br /> Rt Dff is very slow, and the hazard of water erosion is Included in this unit are small areas of Archerdale
<br /> sli, t. The rate of water intake in irrigated areas is 0.3 soils and small areas of Jacktone soils that have
<br /> inch per hour. The soil is subject to rare flooding, which moderately coarse textured overwash. Both of these
<br /> oc irs during years of abnormally high precipitation. included soils are on the slightly higher parts of the
<br /> ost areas are used for irrigated crops. This unit landscape. Also included, in landscape positions similar
<br /> may provide wetland functions and values. These to those of the dominant Jacktone soil, are small areas
<br /> sh- ild be considered in plans for enhancement of of Hollenbeck and Stockton soils and fine textured soils
<br /> ife habitat or land use conversion. that are highly calcareous or saline-sodic. Included
<br /> nis unit is suited to irrigated row and field crops. areas make up about 15 percent of the total acreage.
<br /> The main limitations are subsidence and the high water Permeability is slow in the Jacktone soil. Available
<br /> to Because this soil is subject to differential water capacity is moderate. The shrink-swell potential is
<br /> sG_.;idence, frequent leveling of the fields is needed to high. The effective rooting depth is limited by the
<br /> improve the efficiency of irrigation. Areas adjacent to hardpan at a depth of 20 to 40 inches. Depth to the
<br /> le, as are subject to lateral seepage in wet years when water table is more than 5 feet, but water may be briefly
<br /> th, vater level is high. Careful applications of irrigation perched above the hardpan after periods of heavy
<br /> ^dater are needed to prevent the buildup of a high water rainfall or irrigation. Runoff is slow, and the hazard of
<br /> Large ditches and small spud ditches provide water erosion is slight. The rate of water intake in
<br /> "rigation and improve drainage. Subirrigation, irrigated areas is 0.1 inch per hour. The soil is subject
<br /> furrow, border. and sprinkler systems are suitable. to rare flooding, which occurs during years of
<br /> Where a subirrigation system is used, the water table is abnormally high precipitation.
<br /> ra �d to a depth of 1 foot at planting time and then is Most areas are used for irrigated crops, orchards, or
<br /> sl(-..ly lowered during the growing season until it is at a vineyards. A few areas are used as irrigated pasture or
<br /> depth of about 5 feet at harvest time. Maintaining crop for urban development. This unit may provide wetland
<br /> re lue on or near the surface helps to prevent functions and values. These should be considered in
<br /> ssive runoff and increases the rate of water intake plans for enhancement of wildlife habitat or land use
<br /> ��d the organic matter content. Levees should be conversion.
<br /> :ked periodically, and a proper maintenance This unit is suited to irrigated row, field, orchard, and
<br /> %r ram should be developed. vineyard crops. The main limitations are the slow
<br /> nis map unit is in capability units Illw-2 (MLRA-16), permeability and depth to the hardpan. Because of the
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