LOCATION MIDDLEBOX               OR

Established Series
Rev. RDK/TDT/TM
12/2022

MIDDLEBOX SERIES

The Middlebox series consists of moderately deep, well drained soils on hillslopes. They formed in residuum and colluvium from pumiceous and tuffaceous material. Middlebox soils are on slopes of 5 to 40 percent. The mean annual precipitation is about 12 inches and the mean annual temperature is about 43 degrees F.

TAXONOMIC CLASS: Ashy-skeletal, glassy, nonacid, frigid Vitrandic Torriorthents

TYPICAL PEDON: Middlebox gravelly sandy loam - rangeland. (Colors are for dry soil unless otherwise noted.)

A--0 to 4 inches; light brownish gray (10YR 6/2) gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine granular and weak medium platy structure; soft, very friable, nonsticky and nonplastic; common fine and very fine roots; many very fine irregular pores; 30 percent sand-size ash, 20 percent gravel-size pumice; neutral (pH 6.9); clear wavy boundary. (2 to 10 inches thick)

AC--4 to 10 inches; pale brown (10YR 6/3) very gravelly sandy clay loam, dark brown (10YR 3/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; common fine and very fine roots; many very fine irregular pores; 30 percent sand-size ash, 25 percent gravel, 10 percent cobbles; neutral (pH 7.1); clear wavy boundary. (6 to 30 inches thick)

C--10 to 35 inches; pale brown (10YR 6/3) very cobbly sandy clay loam, dark brown (10YR 3/3) moist; massive; soft, very friable, slightly sticky and slightly plastic; common coarse and medium roots; many very fine irregular pores; 30 percent sand-size ash, 20 percent gravel, 25 percent cobble; neutral (pH 7.1); abrupt irregular boundary. (0 to 30 inches thick)

Cr--35 to 40 inches; pumiceous tuff.

TYPE LOCATION: Harney County, Oregon; about 1800 feet north and 1300 feet east of the southwest corner of section 33, T. 38 S., R. 33 E. (Latitude 42 degrees, 13 minutes, 43 seconds N., Longitude 118 degrees, 51 minutes, 0 seconds W. NAD 1927)

RANGE IN CHARACTERISTICS: The soils are dry for one-half to three-fourths of the time when the soil temperature is over 41 degrees F. The mean annual soil temperature is 45 to 47 degrees F. The mean summer soil temperature is 60 to 62 degrees F. The thickness of the solum is 10 to 40 inches thick. Paralithic contact is at 20 to 40 inches. The particle-size control section averages 15 to 30 percent clay, and 35 to 50 percent rock fragments. Phosphate retention is 15 to 25 percent. Volcanic glass is 30 to 50 percent. The acid oxalate aluminum plus one-half the iron is 0.3 to 0.6 percent. It is neutral or slightly alkaline.

The A horizon has hue of 10YR or 7.5YR, value of 5 or 6 dry and 3 or 4 moist and chroma of 2 or 3 dry and moist. Organic matter is less than one percent.

The AC horizon has hue of 7.5YR or 10YR, value of 5 or 6 dry and 3 or 4 moist, and chroma of 2 or 3 dry and moist. It is sandy loam or sandy clay loam with 35 to 50 percent gravel and cobbles.

The C horizon has value of 5 or 6 dry and 3 or 4 moist, and chroma of 2 or 3 dry and moist. It is sandy loam or sandy clay loam with 35 to 50 percent gravel and cobbles.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: The Middlebox soils are on hillslopes. Slopes are 5 to 40 percent. Elevation ranges from 4,700 to 6,000 feet. The soils formed in residuum and colluvium from tuffaceous and pumiceous material. The soils are characterized by cold moist winters and hot dry summers. The mean annual precipitation is 8 to 13 inches. The mean annual temperature is 43 to 45 degrees F. The mean summer temperature is 60 to 62 degrees F. The frost-free period is 50 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Calderwood, Lonegrave, Lonely, Ninemile and Sagehen soils. Calderwood, Lonegrave, Lonely, and Sagehen soils have cambic horizons. Ninemile soils have a clayey argillic horizon.

DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderately rapid permeability.

USE AND VEGETATION: The soils are used for livestock grazing and wildlife habitat. Vegetation is commonly Wyoming big sagebrush, mountain big sagebrush, Thurber needlegrass, bluebunch wheatgrass, and Idaho fescue.

DISTRIBUTION AND EXTENT: Southeastern Oregon; MLRA 23. The series is of minor extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Harney County, Oregon, 1997.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon

Aridic/xeric soil moisture regime

Particle size control section: 10 to 35 inches; (C horizon) has over 30 percent glass and averages 45 percent rock fragments

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National Cooperative Soil Survey
U.S.A.