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Area, Oregon
<br />Ning the existing plant cover during construction
<br />to control erosion. Buildings and roads should be
<br />red to offset the limited ability of the soil to support
<br />. The passibility of settlement. can be minimized by
<br />icting'the building site before construction is
<br />map unit is in capability subclass Vle.
<br />..r:.
<br />=~75--Malabon silty clay loam. This deep, well drained
<br />soil is on broad valley terraces. It formed in silty and
<br />clayey alluvium. Slope is 0 to 3 percent. Areas are
<br />':. elongated in shape and are 3 to 100 acres or more in
<br />size. The vegetation in areas not cultivated is mainly
<br />pouglas-fir, Oregon white oak, ponderosa pine, poison-
<br />oak and other shrubs, and grasses. Elevation is 300 to
<br />650 feet. The average annual precipitation is 40 to 60
<br />inches, the average, annual air temperature is 52 to 54
<br />degrees F, and the average frost-free period is 165 to
<br />210 days.
<br />Typically, the surface layer is very dark brown and
<br />dark brown silty clay loam about 12 inches thick. The
<br />subsoil is dark brown and brown silty clay loam and silty
<br />clay about 30 inches thick. The substratum is brown clay
<br />loam to a depth of 60 inches or more. Stratified sand
<br />and gravel are at a depth of 40 inches or more in some
<br />areas.
<br />Included in this unit are small areas of Chapman,
<br />Coburg, and Salem soils. Included areas make up about
<br />10 percent of the total acreage.
<br />Permeability of this Malabon soil is moderately slow.
<br />Available water capacity is about 9 to 12 inches.
<br />Effective rooting depth is 60 inches or more. Runoff is
<br />slow, and the hazard of water erosion is slight.
<br />This unit is used mainly for row crops, small grain, hay
<br />and pasture, orchards, and urban development. It is also
<br />used for recreation.
<br />This unit is well suited to all climatically adapted crops.
<br />k is potentially one of the most productive units in the
<br />survey area. The silty clay loam surface layer is subject
<br />to compaction if it is worked when moist. It is subject to
<br />puddling if it is left barren during the rainy season.
<br />In summer, irrigation is required for maximum
<br />production of most crops. Sprinkler irrigation is a suitable
<br />method of applying water. Use of this method pehmits
<br />the even, controlled application of water, reduces runoff,
<br />and minimizes the risk of erosion.
<br />Grain and grasses grown on this unit respond to
<br />nitrogen; legumes respond to phosphorus and lime; and
<br />vegetables and berries respond to nitrogen, phosphonus,
<br />and potassium. Returning all crop residue to the soil and
<br />using a cropping system that includes grasses, legumes,
<br />or grass-legume mixtures help to maintain fertility and
<br />tilth.
<br />If this unit is used for hay and pasture, proper stocking.
<br />rates, pasture rotation, and restricted grazing during wet
<br />Periods help to keep the pasture in good condition and
<br />to protect the soil from erosion and compaction.
<br />97
<br />This unit is suited to recreational development. It is
<br />limited mainly by the content of clay in the soil and the
<br />moderately slow permeability.
<br />The main limitations of this unit for homesite and
<br />urban development are the moderately slow permeability
<br />and moderate shrink-swell potential, which may limit the
<br />construction of basements and certain other types of
<br />structures. In summer, irrigation is required for lawn
<br />grasses, shrubs, vines, shade trees, and ornamental
<br />trees.
<br />Septic tank absorption fields are suitable for sewage
<br />disposal on this unit.
<br />This map unit is in capability class I.
<br />76-Malabon-Urban land complex. This map unit is
<br />on broad valley terraces. Slope is 0 to 3 percent. Areas
<br />are irregular in shape and are 3 to 100 acres or more in
<br />size. The native vegetation is mainly Douglas-fir, Oregon
<br />white oak, ponderosa pine, poison-oak and other shrubs,
<br />and grasses. Elevation is 300 to 650 feet. The average
<br />annual precipitation is 40 to 60 inches, the average
<br />annual air temperature is 52 to 54 degrees F, and the
<br />average frost-free period is 165 to 210 days.
<br />This unit is 40 percent relatively .undisturbed Malabon
<br />silty clay loam, 10 percent disturbed Malabon silty clay
<br />loam, and 45 percent Urban land. The components of
<br />this unit are so intricately intermingled that it was not
<br />practical to map them separately at the scale used.
<br />Included in this unit are small areas of Chapman,
<br />Coburg, and Salem soils. Included areas make up about
<br />5 percent of the total acreage.
<br />The relatively undisturbed Malabon soil is deep and
<br />well drained. It formed in silty and clayey alluvium.
<br />Typically, the surface layer is very dark brown and dark
<br />brown silty clay loam about 12 inches thick. The subsoil
<br />is dark brown and brown silty clay loam and silty clay
<br />about 30 inches thick. The substratum is brown clay:
<br />loam to a depth of 60 inches or more. Stratified sand
<br />and gravel are at a depth of 40 inches or more in places.
<br />Permeability of the relatively undisturbed Malabon soil
<br />is moderately slow. Available water capacity is about 9 to
<br />12 inches. Effective rooting depth is 60 inches or more.
<br />Runoff is slow, and the hazard of water erosion is slight.
<br />The disturbed Malabon soil has been covered by as
<br />much as 40 inches of fill material or has had as much as
<br />30 inches of the original profile removed by cutting or
<br />grading. The fill material is commonly from adjacent
<br />areas of Malabon, Coburg, Salem, and Chapman soils
<br />that have been cut or graded. The characteristics of the
<br />disturbed areas are highly variable.
<br />Urban land consists of areas where the soils are
<br />largely covered by concrete, asphalt, buildings, or other
<br />impervious surfaces that obscure or alter the soils so
<br />that identification is not feasible.
<br />This unit is used mainly for urban development. It is
<br />also used for yards, parks, and open areas around and
<br />between buildings.
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