LOCATION MCNULL OREstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Ultic Argixerolls
TYPICAL PEDON: McNull loam, on a north facing concave slope of 33 percent under mixed conifers at 2,060 feet elevation. (When described the soil was moist throughout. Colors are for moist soil unless otherwise noted.)
0--1 inch to 0; partially decomposed leaves, needles, and twigs.
A1--0 to 2 inches; dark reddish brown (5YR 3/3) loam, brown (7.5YR 4/2) dry; weak very fine granular structure; soft, very friable, slightly sticky and slightly plastic; common very fine roots; many very fine and fine interstitial pores; 10 percent gravel; slightly acid; abrupt smooth boundary. (2 to 4 inches thick)
A2--2 to 6 inches; dark reddish brown (5YR 3/3) loam, brown (7.5YR 4/2) dry; moderate fine subangular blocky structure; slightly hard, very friable, sticky and slightly plastic; common very fine and fine roots; many very fine and fine interstitial pores; 10 percent gravel; slightly acid; clear wavy boundary. (3 to 7 inches thick)
Bt1--6 to 12 inches; dark reddish brown (5YR 3/3) clay loam, dark brown (7.5YR 4/2) dry; moderate fine and medium subangular blocky structure; hard, friable, sticky and plastic; common very fine, fine, and medium roots; common fine interstitial and few very fine tubular pores; few thin clay films on ped faces and in pores; 10 percent gravel; moderately acid; clear wavy boundary. (3 to 7 inches thick)
Bt2--12 to 25 inches; dark reddish brown (5YR 3/4) cobbly clay, dark brown (7.5YR 3/4) dry; moderate medium angular blocky structure; very hard, firm, very sticky and very plastic; common very fine, fine and medium roots; common very fine interstitial and common fine tubular pores; many moderately thick clay films on ped faces and in pores; 10 percent gravel and 10 percent cobbles; moderately acid; gradual irregular boundary. (10 to 18 inches thick)
Bt3--25 to 32 inches; dark reddish brown (5YR 3/4) cobbly clay, brown (7.5YR 4/4) dry; moderate medium angular blocky structure; very hard, firm, very sticky and very plastic; common very fine, fine and medium roots; common very fine interstitial and common fine tubular pores; many moderately thick clay films on ped faces and in pores; 10 percent gravel and 10 percent cobbles; moderately acid; abrupt irregular boundary. (0 to 8 inches thick)
Crt--32 inches; fractured soft volcanic bedrock with dark brown (5YR 4/4) clay in fractures.
TYPE LOCATION: Jackson County, Oregon; about 5 miles northeast of the city of Eagle Point; 1,400 feet south and 1,100 feet east of the northwest corner of sec. 8, T. 35 S., R. 1 E.
RANGE IN CHARACTERISTICS: The soils are usually moist but are dry between depths of 4 to 12 inches for 80 to 110 consecutive days in the four months that follow the summer solstice. The mean annual soil temperature is 47 to 54 degrees F. Depth to a paralithic contact is 20 to 40 inches. Solum thickness is typically 25 to 38 inches. The particle-size control section averages 10 to 35 percent rock fragments of which 5 to 20 percent are gravel and 5 to 15 percent are cobbles. The control section averages 35 to 50 percent clay.
The A horizon has hue of 10YR, 7.5YR, and 5YR, value of 2 or 3 moist, 3 through 5 dry, and chroma of 2 or 3 moist and dry. It has 0 to 35 percent rock fragments of which 0 to 30 percent are gravel and 0 to 5 percent cobbles.
The Bt horizon has hue of 10YR, 7.5YR, and 5YR, value of 3 through 5 moist and dry, and chroma of 3 through 6 moist and dry. It has 10 to 35 percent rock fragments of which 5 to 20 percent are gravel and 5 to 15 percent are cobbles. It is strongly or moderately acid.
COMPETING SERIES: This is the Applegate series. Applegate soils are on terraces and are over 60 inches deep to bedrock.
GEOGRAPHIC SETTING: The McNull series consists of moderately deep, well drained soils on mountainslopes. These soils formed in colluvium derived dominantly from tuffs and breccias. Elevation is 1,500 to 4,000 feet. The mean annual precipitation is about 20 to 40 inches. The mean annual temperature is 45 to 52 degrees F. The frost-free period is 100 to 160 days. Slopes range from 12 to 60 percent.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bybee, Medco, McMullin, and Tatouche soils. Bybee and Tatouche soils have frigid soil temperatures. McMullin soils are 12 to 20 inches deep and lack an argillic horizon. Medco soils lack an argillic horizon and are typically 10YR.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; slow permeability.
USE AND VEGETATION: These soils are used for timber production, grazing, wildlife habitat, and pasture. Native vegetation is ponderosa pine, Pacific madrone, Douglas fir, whiteleaf manzanita, California black oak, poison oak, and wild rose.
DISTRIBUTION AND EXTENT: Western Cascade Mountains in southwestern Oregon. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Jackson County Area, Oregon, 1988.