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<br />County, California
<br />[ting depth is limited by the bedrock at a depth of 10
<br />'20 inches. Runoff is slow or medium, and the hazard
<br />f water erosion is slight or moderate.
<br />The Lithic Xerorthents are very shallow and are
<br />oderatoly wall drained and wall drainod. Tlmy tanned
<br />n material weathered from hard, rhyolitic, tuffaceous
<br />ndstone. Typically, 1 to 3 percent of the surface is
<br />vered with cobbles. The surface layer is light
<br />brownish gray gravelly loam about 3 inches thick.
<br />hite, rhyolitic, tuffaceous sandstone bedrock is at a
<br />depth of 3 inches. In some areas the surface layer is
<br />gravelly sandy loam or loam.
<br />Permeability is moderate in the Lithic Xerorthents.
<br />Available water capacity is very low. The effective
<br />rooting depth is limited by the bedrock at a depth of 1 to
<br />4 inches. Runoff is rapid, and the hazard of water
<br />erosion is moderate.
<br />Most areas of this unit are used for livestock grazing.
<br />General management considerations include the very
<br />low available water capacity, the limited depth, and the
<br />hazard of erosion. The characteristic plant community
<br />on the Amador soil is soft chess, ripgut brome, (oxtail
<br />fescue, and filaree. The Lithic Xerorthents support only
<br />a sparse stand of plants that are suitable for grazing.
<br />These plants are soft chess, toad rush, and hairgrass.
<br />The very low available water capacity limits the
<br />production oI dusnablo Imago plants. Fancwal Is ddhcull
<br />because of the limited depth to bedrock. Grazing should
<br />be controlled so that desirable vegetation, such as soft
<br />chess, is maintained and enough vegetation is left
<br />standing to protect the soils from erosion. Loss of the
<br />surface layer results in a severe decrease in
<br />productivity and in the potential of the unit to produce
<br />plants suitable for grazing.
<br />This map unit is in capability subclass We
<br />(MLRA-18), nonirrigated. It is in vegetative soil group G.
<br />106—Archerdale very fine sandy loam, 0 to 2
<br />percent slopes, overwashed. This very deep, well
<br />drained, nearly level soil is on alluvial fans. It formed in
<br />alluvium derived from mixed rock sources. A few areas
<br />are dissected by intermittent sloughs that have been
<br />filled as a result of land leveling. Elevation is 60 to 90
<br />feet. The average annual precipitation is about 14
<br />inches, the average annual air temperature is about 60
<br />degrees F, and the average frost -free period is about
<br />270 days.
<br />Typically, the surface layer is brown very fine sandy
<br />learn ghoul III jlwhw. (hick huh,w Ihlu in a hunud
<br />surface layer of dark grayish brown clay loam about 20
<br />inches thick. The subsoil to a depth of 60 inches is
<br />brown clay. In some areas the surface layer is fine
<br />sandy loam, silt loam, or clay loam.
<br />Included in this unit are small areas of Columbia soils
<br />%00
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<br />in the slightly lower landscape positions. Also included
<br />are small areas of Cogna, Finrod, and Hallenbeck soils
<br />in landscape positions similar to those of the Archerdale
<br />soil. Included areas make lip about 15 percent of the
<br />total .rrauagu.
<br />Permeability is slow in the Archerdale soil. Available
<br />water capacity is high. The shrink -swell potential also is
<br />high. The effective rooting depth is 60 inches or more.
<br />Runoff is slow, and the hazard of water erosion is
<br />slight. The rate of water intake in irrigated areas is 1.0
<br />inch per hour. The hazard of soil blowing is moderate.
<br />The soil is subject to rare flooding, which occurs during
<br />years of abnormally high precipitation.
<br />Most areas are used for irrigated crops or orchards.
<br />A few areas are used for homesite development. This
<br />unit may provide wetland functions and values. These
<br />should be considered in plans for enhancement of
<br />wildlife habitat or land use conversion.
<br />This unit is suited to irrigated row, field, and orchard
<br />crops. The main limitation is the slow permeability
<br />below the overwash layer. General management
<br />considerations include the hazard of soil blowing.
<br />Because of the restricted permeability, water
<br />applications should be regulated so that the water does
<br />not stand on the surface and damage the crops.
<br />Furrow, border, and sprinkler irrigation systems are
<br />arnlul,lu. When Ihu wind vulorlly is high in sprint(, Ihu
<br />hazard of soil blowing can be reduced by properly
<br />managing all crop residue and by minimizing tillage.
<br />If this unit is used for homesite development, the
<br />main limitations are the high shrink -swell potential, low
<br />strength, and the slow permeability below the overwash.
<br />The rare flooding is a hazard. Properly designing
<br />foundations and footings and diverting runoff away from
<br />buildings help to prevent the structural damage caused
<br />by shrinking and swelling. Properly designing buildings
<br />and roads can offset the limited ability of the soil to
<br />support a load. On sites for septic tank absorption
<br />fields, the slow permeability can be overcome by
<br />increasing the size of the absorption field. Houses,
<br />roads, and streets should be constructed above
<br />expected flood levels.
<br />This map unit is in capability units IIs -3 (MLRA-17),
<br />irrigated, and IVs -3 (MLRA-17), nonirrigated. It is in
<br />vegetative soil group A.
<br />107—Archerdale clay loam, 0 to 2 percent slopes.
<br />This very deep, well drained, nearly level soil is on low
<br />Lar luuacw. II Innnud in alluvium durivud from mixod
<br />rock sources. A iuw aruas are dissected by intermittent
<br />sloughs that have been filled as a result of land
<br />leveling. Elevation is 40 to 130 feet. The average
<br />annual precipitation is about 14 inches, the average
<br />annual air temperature is about 60 degrees F, and the
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