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16
<br />SOIL SURVEY
<br />films on vertical and horizontal faces of peds ; non-
<br />calcareous; clear, smooth boundary.
<br />B22tb-16 to 29 inches, dark-gray (10YR 4/1) clay loam, black
<br />(10YR 2/1) when moist ; strong, medium and fine,
<br />prismatic structure that breaks to strong, fine, angular
<br />blocky ; slightly hard when dry, firm when moist ;
<br />thick, continuous clay films on vertical and horizontal
<br />faces of peds ; noncalcareous ; clear, smooth boundary.
<br />B3b-29 to 37 inches, light brownish-gray (10YR 6/2) clay
<br />loam, dark grayish brown (IOYR 4/2) when moist;
<br />moderate, medium, prismatic structure that breaks to
<br />moderate, medium, subangular blocky ; slightly hard
<br />when dry, friable when moist; noncalcareous; thin,
<br />patchy clay films ; many krotovinas filled with material
<br />from above, very dark grayish brown (10YR 3/2)
<br />when moist ; clear, smooth boundary.
<br />Cca-37 to 60 inches, pale-brown (IOYR 6/3) loam, dark brown
<br />(10YR 4/3) when moist; weals, medium and thick,
<br />prismatic structure that breaks to weak, medium and
<br />coarse, subangular blocky ; soft when dry, very friable
<br />when moist ; very strongly calcareous ; a layer of
<br />very fine sandy loam, dark brown (10YR 4/3) when
<br />moist, is at a depth of 46 to 60 inches ; many kroto-
<br />vinas ; gradual boundary.
<br />In thickness, the A horizon ranges from 5 to 10 inches and
<br />the B21t horizon ranges from 6 to 15 inches. Depth to the top
<br />of the buried soil ranges from 12 to 1S inches. In some areas
<br />gravelly material underlies these soils at a depth of only 40
<br />inches.
<br />Iiuma soils have less clay in their subsoil than Rago or
<br />Richfield soils. Iiuma soils are deeper to the limy substratum
<br />than are Richfield soils and have weaker structure throughout.
<br />Platner Series
<br />The Platner series consists of deep, Nvell-drained, loamy
<br />soils that are nearly level to moderately sloping. These
<br />soils are extensive in the hardlands in the southwestern
<br />part of the county. A few areas are also along the banks of
<br />small intermittent drainageways. These soils formed in a
<br />thin silty deposit of windblown material that has been
<br />mixed to some extent with the underlying sand and gravel.
<br />In a typical profile the plow layer is grayish-brown loam
<br />about 5 inches thick. Fine gravel makes up about 5 percent
<br />of this layer. Clean sand grains are evident in the lower
<br />inch of this layer.
<br />The subsoil is about 12 inches thick. The upper part,
<br />about 7 inches thick, is dark grayish-brown clay that is
<br />very hard when dry and firm when moist. The lower part
<br />is dark grayish-brown clay loam that is very hard when
<br />dry and friable when moist.
<br />The underlying material is very pale brown, very
<br />strongly calcareous loam that is more sandy and limy as
<br />depth increases.
<br />These soils have high natural fertility and available
<br />water holding capacity. They are well suited to dryland
<br />cultivation under normal management, but soil blowing
<br />and water erosion are hazards in cultivated areas. Plow-
<br />pans form easily in these soils if they are tilled when wet.
<br />Almost all the acreage is dryfarmed, mainly to winter
<br />wheat, barley, oats, and sorghums. In a few undisturbed,
<br />generally small areas, the native vegetation is mainly
<br />grama grasses.
<br />Typical profile of Platner loam, 0 to 3 percent slopes, in
<br />a field of winter wheat (1,890 feet east and 200 feet north
<br />of the southwest corner of section 16, T. 7 N., R. 46 W.)
<br />Ap-0 to 5 inches, grayish-brown (10YR 5/2) loam, very dark
<br />grayish brown (10YR 3/2) when moist; moderate,
<br />fine, granular structure ; slightly hard when dry,
<br />friable when moist ; bleached sand grains and specks
<br />of light brownish gray (10YR 6/2) are evident in a
<br />layer 1 or 2 inches thick ; 5 percent fine gravel ; pH
<br />6.4; noncalcareous ; abrupt, smooth boundary.
<br />B2t-5 to 12 inches, dark grayish-brown (10YR 4/2) clay, very
<br />dark grayish brown (10YR 3/2) when moist; strong,
<br />medium and fine, prismatic structure that breaks to
<br />strong, medium, angular blocky ; very hard when dry,
<br />firm when moist; moderate, continuous clay films on
<br />vertical and horizontal ped faces ; some bleached sand
<br />grains on tops of prisms ; pH 7.2; nonealcareous ;
<br />clear. smooth boundary.
<br />133-12 to 17 inches, dark grayish-brown (10YR 4/2) light clay
<br />loam, (lark grayish brown (10YR 4/2) when moist;
<br />weak to moderate, medium, prismatic structure that
<br />breaks to weak to medium subangular blocky ; very
<br />hard when dry, friable when moist; thin, patchy clay
<br />films on vertical and horizontal ped faces; streaks of
<br />very dark grayish brown (10YR 3/2) when moist, and
<br />brown (10YR 4/3) when moist, on some vertical
<br />ped faces ; pH 7.6; noncalcareous ; clear, smooth
<br />boundary.
<br />Clea-17 to 24 inches, very pale brown (10YR 8/3) loam, pale
<br />brown (10YR 6/3) when moist; weak, coarse, pris-
<br />matic structure that breaks to weak, coarse, sub-
<br />angular blocky ; bard when dry, friable when moist;
<br />strong accumulation of visible finely divided lime ;
<br />pH 9.0; very strongly calcareous ; clear, smooth
<br />boundary.
<br />IIC2ca-24 to 48 inches, light yellowish-brown (10YR 6/4) fine
<br />sandy clay loam, yellowish brown (IOYR 5/4) when
<br />moist; massive (structureless) ; hard when dry, very
<br />friable when moist; 40 to 50 percent fine gravel;
<br />moderate accumulation of lime in which visible lime
<br />occurs in finely divided forms, as coatings on the
<br />pebbles, and as common, medium-sized soft concre-
<br />tions ; lower 14 inches slightly more sandy and con-
<br />tains more lime than upper part of horizon; pH 9.0;
<br />very strongly calcareous ; clear, wavy boundary.
<br />IIC3--48 to 60 inches, pinkish-white (7.5YR 8/2) very fine
<br />sandy clay loam, pink (7.5YR 7/4) when moist;
<br />massive (structureless) ; very hard when dry, friable
<br />when moist; strong accumulation of lime in marllike
<br />material ; pH 9.0; very strongly calcareous.
<br />The A horizon has little range in color or texture. In most
<br />areas it shows bleaching or clean sand grains on the structure
<br />faces in the lower inch, but the sand grains are normally mixed
<br />with the plow layer in cultivated areas. The A horizon ranges
<br />from 4 to 7 inches in thickness. The B horizon ranges from 5
<br />to 12 inches in thickness and from dark grayish brown to
<br />dark brown in color. It is heavy clay loam or clay. Depth to
<br />lime ranges from 10 to 20 inches.
<br />Platner soils developed in a thinner deposit of loess than the
<br />Rago .soils, and they lack the dark, buried layer that occurs in
<br />the Rago soils. The subsoil of Platner soils is more clayey and
<br />more strongly developed than that of Ascalon soils.
<br />Platner loam, 0 to 3 percent slopes (PaB) mainly oc-
<br />cupies convex areas that are irregular in shape and are
<br />elongated in a southeast-northwest direction. This soil is
<br />also on side slopes along intermittent drainageways. Its
<br />profile is the one described as typical for the series.
<br />Included with this soil in mapping were small areas of
<br />nearly level Rago soils in slightly depressional areas. Also
<br />included were a few small spots of gravel or caliche out-
<br />crops, which are shown on the soil map by a symbol.
<br />Nearly all of this soil is cultivated. Soil blowing and wa-
<br />ter erosion are only slight in dryfarmed areas that are
<br />managed well, but plowpans form easily if this soil is
<br />tilled when wet. Suitable dryfarming practices are use of
<br />stubble mulch and crop residue. Where irrigated, this soil
<br />can be leveled so that water spreads uniformly and is not
<br />wasted. In irrigated areas, crop residue should be worked
<br />into the soil so as to maintain tilth and reduce erosion.
<br />Grass can be seeded and irrigated and then used for hay or
<br />pasture.
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