The Boontling series consists of very deep, somewhat poorly drained soils that formed in alluvium derived from mixed rock sources. These soils are on river terrace platforms and associated scarps. Slopes range from 2 to 30 percent. The mean annual precipitation is about 45 inches, and the mean annual air temperature is about 56 degrees F.

These soils are classified as fine-loamy, mixed, thermic Ultic Argixerolls.

Typical pedon of Boontling loam, 2 to 9 percent slopes, 2,000 feet south and 1,400 feet east of the northwest corner of sec. 35, T. 14 N., R. 14 W., MDBM, Boonville Southwest quadrangle:

Ap—0 to 6 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; common very fine and fine tubular and interstitial pores; moderately acid (pH 5.8); clear wavy boundary.

A—6 to 12 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; moderate fine, medium, and coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; common very fine and fine tubular and interstitial pores; moderately acid (pH 5.8); gradual wavy boundary.

Bt1—12 to 23 inches; pale brown (10YR 6/3) loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; common very fine and fine tubular and interstitial pores; common moderately thick and thick clay films on faces of peds and lining pores; 5 percent hard subrounded gravel; slightly acid (pH 6.4); clear wavy boundary.

Bt2—23 to 30 inches; very pale brown (10YR 7/3) loam, brown (10YR 5/3) moist; common fine and medium distinct brownish yellow (10YR 6/6) mottles, dark yellowish brown (10YR 4/6) moist; moderate fine and medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few very fine roots; common very fine and fine tubular and interstitial pores; common moderately thick and thick clay films on faces of peds and lining pores; 10 percent soft subrounded gravel (2 to 15 millimeters); neutral (pH 6.8); clear wavy boundary.

Bt3—30 to 40 inches; light yellowish brown (2.5Y 6/4) clay loam, olive brown (2.5Y 4/4) moist; common fine distinct light gray (2.5Y 7/2) and many medium prominent brownish yellow (10YR 6/6) mottles, grayish brown (2.5Y 5/2) and dark yellowish brown (10YR 4/6) moist; strong fine, medium, and coarse subangular blocky structure; very hard, firm, sticky and plastic; few very fine roots; few very fine and fine tubular and interstitial pores; many moderately thick and thick clay films on faces of peds and lining pores; 10 percent soft subrounded gravel; neutral (pH 7.0); clear wavy boundary.

Bt4—40 to 60 inches; light yellowish brown (10YR 6/4) gravelly clay loam, olive brown (2.5Y 4/4) moist; common fine distinct light gray (2.5Y 7/2) and many fine and medium faint brownish yellow (10YR 6/6) mottles, grayish brown (2.5Y 5/2) and dark yellowish brown (10YR 4/6) moist; strong medium and coarse subangular blocky structure; very hard, very firm, sticky and plastic; few very fine roots; few very fine and fine tubular and interstitial pores; continuous moderately thick and thick clay films on faces of peds and lining pores; 15 percent soft to hard subrounded gravel and 5 percent hard subrounded cobbles; neutral (pH 7.2).

The depth to bedrock is more than 60 inches. The mollic epipedon is 10 to 20 inches thick and has 1 to 4 percent organic matter. The mean annual soil temperature ranges from 59 to 62 degrees F. The soil between the depths of 6 and 19 inches is moist in all parts from November 1 to June 15 and is dry in all parts from August 1 to October 1 in most years. The soil is saturated with water for brief or long periods following episodes of heavy rain from December through May. The saturated zone starts between the depths of 30 and 40 inches and extends to a depth of more than 60 inches. The soil is not saturated above a depth of 60 inches from summer through early fall.

The A horizon has color of 10YR 4/2, 5/2, or 5/3. Moist color is 10YR 2/2, 3/2, or 3/3. The content of clay ranges from 18 to 25 percent. Base saturation ranges from 50 to 75 percent. Reaction is moderately acid or slightly acid.

The Bt horizon has color of 2.5Y 6/4 or 10YR 5/4, 6/3, 6/4, 7/2, or 7/3. Moist color is 2.5Y 4/4, 5/4, or 6/4 or 10YR 3/3, 4/2, 4/3, 5/2, 5/3, 5/4, 6/2, 6/3, or
6/4. Mottles have dry color of 2.5Y 6/2 or 7/2 or 10YR 6/4, 6/6, or 6/8 and moist color of 2.5Y 5/2 or 10YR 4/6, 5/4, 5/6, or 5/8. The texture of this horizon is loam, silt loam, silty clay loam, clay loam, clay, gravelly sandy clay loam, or gravelly clay loam. The content of clay ranges from 22 to 27 percent in the upper part and from 22 to 45 percent in the lower part. The content of gravel ranges from 0 to 35 percent. The content of cobbles ranges from 0 to 10 percent. Gravelly textures, if they occur, are typically below a depth of 40 inches. Base saturation ranges from 75 to 90 percent. Reaction ranges from moderately acid to neutral.