LOCATION KRUM TXEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Udertic Haplustolls
TYPICAL PEDON: Krum silty clay--cultivated. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 6 inches; dark grayish brown (10YR 4/2) silty clay, very dark brown (7.5YR 2/2) moist; moderate fine subangular blocky and moderate medium granular structure; hard, firm, sticky, plastic; common roots; few fine pores; few strongly cemented calcium carbonate concretions up to 5 mm in diameter; few white flakes of calcium carbonate, some of which are fragments of snail shells; calcareous; moderately alkaline; clear smooth boundary. (0 to 8 inches thick)
A--6 to 26 inches; very dark grayish brown (10YR 3/2) silty clay, very dark brown (10YR 2/2) moist; moderate very fine subangular blocky and very fine angular blocky structure; hard, firm, sticky, plastic; few very fine weakly cemented calcium carbonate concretions; few very fine whitish soft masses of calcium carbonate in the lower part; common roots; many fine pores; calcareous; moderately alkaline; gradual wavy boundary. (12 to 36 inches thick)
Bw--26 to 44 inches; brown (7.5YR 5/4) silty clay, dark brown (7.5YR 4/4) moist; moderate medium angular blocky structure; peds have shiny pressure faces; hard, very firm, sticky, plastic; darker soil from horizon above extends to bottom of this layer along partially sealed cracks; few fine roots; common fine pores; less than 1 percent weakly to strongly cemented calcium carbonate concretions and fine powdery masses of calcium carbonate; calcareous; moderately alkaline; gradual wavy boundary. (18 to 50 inches thick)
Bk1--44 to 62 inches; reddish yellow (7.5YR 6/6) silty clay, strong brown (7.5YR 5/6) moist; weak coarse angular blocky structure; hard, firm, sticky, plastic; few fine roots; 5 percent calcium carbonate weakly to strongly cemented concretions and a few powdery masses; calcareous; moderately alkaline; diffuse wavy boundary. (14 to 32 inches thick)
Bk2--62 to 72 inches; reddish yellow (7.5YR 6/6) silty clay, strong brown (7.5YR 5/6) moist; weak coarse subangular blocky structure; hard, firm, sticky, plastic; 2 percent weakly and strongly cemented concretions and powdery masses; calcareous; moderately alkaline.
TYPE LOCATION: Williamson County, Texas; 13.5 miles south 45 degrees east from the courthouse in Georgetown, and about 2.3 miles south of Hutto; from the intersection of Farm Road 1660 and a paved road 0.3 mile east-southeast of Norman; 2.9 miles west-northwest along Farm Road 1660; 200 feet south of the farm road in cultivated field.
RANGE IN CHARACTERISTICS: Solum thickness is 40 to greater than 80 inches. The soils, when dry, have cracks 0.4 to 1.2 inches wide that extend from the surface to depths of about 24 to 48 inches. The 10- to 40-inch control section is silty clay or clay containing 40 to 60 percent clay, 0 to 10 percent limestone pebbles and about 15 to 30 percent calcium carbonate equivalent with visible forms of calcium carbonate varying form none to about 2 percent by volume.
The A horizons have hue of 7.5YR or 10YR, value of 3 to 5, and chroma of 1 to 3. Thickness of the horizons having moist value and chroma of less than 3.5 is 14 to 36 inches. Texture is clay, silty clay, clay loam, or silty clay loam, with the loamy textures occurring at depths of less than 12 inches or in an Ap horizon. Structure is compound moderate to strong very fine subangular to angular blocky and medium granular. It is moderately alkaline or mildly alkaline, and the upper 10 inches is noncalcareous in some pedons.
The Bw horizon has color with hue of 5YR to 10YR, value of 5 or 6, and chroma of 2 to 4. Structure is compound moderate medium to fine angular blocky and subangular blocky. Visible concretions and powdery masses bodies range from less than 1 percent to about 10 percent by volume.
The Bk horizons have color with hue of 5YR to 10YR, value of 6, and chroma of 3 to 6. Texture is silty clay loam, silty clay, or clay. Calcium carbonate segregations range from 2 to 20 percent by volume. Calcium carbonate equivalent ranges from 20 to 50 percent.
COMPETING SERIES: Behring is the only other soil in the same family. Similar soils include Bippus, Denton, Knippa, Lewisville, Matoy, Miller, Moreland, Pledger, Raymondville, Rioconcho, Rowena, and Volente series. Behring soils are noncalcareous to a depth of 40 inches. Bippus, Lewisville, and Volente soils, when dry, do not have cracks as wide as 0.4 inch. In addition, Lewisville soils have mollic epipedons less than 20 inches thick. Denton soils are less than 60 inches deep over limestone. Knippa and Rowena soils have calcic horizons at depth of less than 40 inches. Matoy soils have limestone bedrock at depths of 20 to 40 inches. Miller, Moreland, Pledger, and Rioconcho soils have an irregular decrease in organic matter as depth increases. Raymondville soils have average annual temperatures of more than 72 degrees F.
GEOGRAPHIC SETTING: Krum soils are on nearly level stream terraces and gently sloping filled valleys. The soil formed in thick beds of unconsolidated calcareous, clayey sediments, probably of Pleistocene age. The climate is moist subhumid to dry subhumid. Mean annual precipitation is about 26 to 36 inches and mean annual temperature is 63 to 70 degrees F. Frost free days range from 230 to 250 days and elevation ranges from 600 to 1,300 feet. Thornthwaite P-E indices ranges from 38 to 58.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Denton, Lewisville, and Volente series and Branyon, Crawford, Frio, and Tarrant series. Denton, Lewisville, and Volente soils occur on similar surfaces. Branyon, Crawford, and Tarrant soils occur at higher elevations. Branyon and Crawford soils have intersecting slickensides. Frio soils occur at lower elevations in flood plains and lack vertic properties. Tarrant soils have sola less than 20 inches thick over limestone and they contain more than 35 percent coarse fragments.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is slow to rapid. Permeability is moderately slow.
USE AND VEGETATION: About two-thirds is cropped to cotton, sorghums, and small grains. The remainder is used for rangeland. The vegetation is tall and mid-grasses, and a few clumps of live oak and other hardwood trees.
DISTRIBUTION AND EXTENT: Texas and possibly Oklahoma. Most areas are in the Texas Blackland Prairie, Grand Prairie and the Edward Plateau. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: McLennan County, Texas; 1943.
REMARKS: This series now includes some soils formerly included in the Lewisville series. Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 26 inches (Ap and A horizons)
Cambic horizon - 26 to 44 inches (Bw horizon)
Calcic horizon - 44 to 62 inches (Bk1 horizon)
Reference Data: Lincoln Lab Data Sample Nos. 72L438 and 72L439; SSIR-30-S57TX-18-90.