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San Joaquin County, California 119
<br /> absorption fields, the very slow permeability can be alluvium derived from granitic rock sources. Typically,
<br /> overcome by increasing the size of the absorption field, the surface layer and the upper part of the subsoil are
<br /> aja kfilling the trench with sandy material, and installing brown loam about 16 inches thick. The next 10 inches
<br /> 'fon
<br /> h,"9 absorption lines. Ripping the hardpan. improves of the subsoil is a claypan of brown clay. The lower part
<br /> :
<br /> R�meability and thus also improves the suitability for to a depth of 60 inches is a brown and light brown,
<br /> septic tank absorption fields. Excavation for buildings is indurated hardpan. In some areas the surface layer is
<br /> ;invited by the hardpan. Properly designing foundations silt loam.
<br /> an,,footings and diverting runoff away from buildings Permeability is very slow in the San Joaquin soil.
<br /> help to prevent the structural damage caused by Available water capacity is low. The shrink-swell
<br /> shrinking and swelling. Properly designing buildings and potential is high. The effective rooting depth is limited
<br /> scan offset the limited ability of the soils to support by the hardpan at a depth of 20 to 40 inches. Roots are
<br /> oad. restricted to cracks and the faces of ed in
<br /> a.L.., p s the
<br /> his unit is suited to irrigated row, field, and vineyard claypan; which is at a depth of 10 to 20 inches. Water
<br /> erops. The main limitations are depth to the very slowly is briefly perched above the claypan and hardpan after
<br /> rmeable claypan, and hardpan and the,low available periods of heavy rainfall. Runoff is slow, and the hazard
<br /> water capacity in some areas. Because of the restricted of water erosion is slight. The rate of water intake in
<br /> permeability, water applications should be regulated so irrigated areas is 1.0 inch per hour.
<br /> tlat;the water does not stand on the surface and, Urban land consists of areas covered by roads,
<br /> 4amage the crops. The hardpan limits the suitability for driveways, sidewalks, parking lots, buildings, and other
<br /> deep=rooted crops. Where feasible,.deep ripping of this structures. The soil material under the impervious
<br /> restrictive layer can help to overcome this limitation. A surface is similar to that of San Joaquin loam.
<br /> tillage pan forms easily if these soils are tilled when Most areas are used for urban development. A few
<br />'i wet'Chiseling or subsoiling breaks up the pan. Because areas are used for irrigated crops. This, unit may
<br /> :of.:droughtiness, applications of irrigation water should provide wetland functions and values. These should be
<br /> te'fght and frequent. Furrow, .border, and sprinkler considered in plans for enhancement of wildlife habitat
<br /> irng_ation systems are suitable. Returning crop residue or land use conversion.
<br /> to;tle soils or regularly adding other organic material Where the San Joaquin sail is used for urban
<br /> improves fertility, minimizes crusting, and increases the development, the main limitations are depth to the very
<br /> rafero,f water intake. slowly permeable claypan and hardpan, the high shrink-
<br /> is map unit is in capability unit IVs-3 (MLRA-17), swell potential, and low strength in the claypan. On
<br /> rrgated and nonirrigated. It is in vegetative soil group sites for septic tank absorption fields, the very slow
<br /> D permeability can be overcome by increasing the size of
<br /> the absorption field, backfilling the french with sandy
<br /> 242-San Joaquin-Urban land complex, 0 to 2 material, and installing long absorption lines. Ripping
<br /> pe, cent slopes. This nearly level map unit is on low the hardpan improves permeability and thus also
<br /> terEraces. Elevation is 20 to 110 feet. The average improves the suitability of the soil for septic tank
<br /> annual.precipitation is about 16 inches, the average absorption fields. Excavation for buildings is limited by
<br /> annual air temperature is about 61 degrees F, and the the hardpan. Properly designing foundations and
<br /> avefage frost-free period is about 275 days. footings and diverting runoff away from buildings help to
<br /> 7lis unit is 50 percent San Joaquin loam and 35 prevent the structural damage caused by shrinking and
<br />' percent Urban land. The components of this unit occur swelling. Properly designing buildings and roads can
<br /> as-areas so intricately intermingled that it was not offset the limited ability of the soil to support a load.
<br /> P a deal to map them separately at the scale used. The San Joaquin soil is suited to irrigated row, field,
<br /> Included in this unit are small areas of Kingdon and and vineyard crops. The main limitations are depth to
<br /> laI op, soils on the slightly higher parts of the the very slowly permeable claypan and hardpan and the
<br /> ndsca e. Also included, in landscape positions similar low available water capacity. Because of the restricted
<br /> to=tle;'San Joaquin soil, are small areas of moderately permeability, water applications should be regulated so
<br /> coarse.:textured soils that have a hardpan at a depth of that the water does not stand on the surface and
<br /> inches and moderately coarse textured soils damage the crops. The hardpan limits the suitability for
<br /> tat`'have been ripped and have remnants of claypan deep-rooted crops. Where feasible, deep ripping of this
<br /> a .ihardpan material. Included areas make up about 15 restrictive layer can help to overcome this limitation. A
<br /> parCerlt.of the total acreage, tillage pan forms easily if the soil is tilled when wet.
<br /> San Joaquin soil is moderately deep to a Chiseling or subsoiling breaks up the pan. Because the
<br /> ha„rdban and is moderately well drained. It formed in soil is droughty, applications of irrigation water should
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