LOCATION PORTER IDEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Cumulic Haploxerolls
TYPICAL PEDON: Porter sandy loam -- on a nearly level flood plain step, in irrigated hayland at 2,940 feet elevation. When described on October 19, 1993, the soil was moist throughout. (Colors are for air-dry soil unless otherwise stated.)
Ap1--0 to 4 inches; dark grayish brown (10YR 4/2) sandy loam, very dark brown (10YR 2/2) moist; moderate medium platy structure parting to weak fine subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; common very fine, fine and medium, few coarse roots; common very fine and fine, few medium irregular pores; 10 percent fine gravel; slightly acid (pH 6.5); clear smooth boundary.
Ap2--4 to 11 inches; dark grayish brown (10YR 4/2) sandy loam, very dark brown (10YR 2/2) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine, fine and medium roots; common very fine, fine and medium, few coarse irregular and tubular pores; 10 percent fine gravel; slightly acid (pH 6.4); clear smooth boundary.
A--11 to 22 inches; dark grayish brown (10YR 4/2) sandy loam, very dark brown (10YR 2/2) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine, fine and medium roots; common very fine and fine, few medium and coarse irregular and tubular pores; 10 percent fine gravel; slightly acid (pH 6.4); clear smooth boundary. (combined A horizon - 10 to 24 inches thick)
Bw--22 to 34 inches; grayish brown (10YR 5/2) sandy loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine and fine, few medium tubular pores; 10 percent fine gravel; neutral (pH 6.6); clear smooth boundary. (7 to 18 inches thick)
BC--34 to 48 inches; brown (10YR 5/3) coarse sandy loam, dark brown (10YR 3/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; few very fine and fine roots; common very fine and fine tubular pores; 10 percent fine gravel; neutral (pH 6.8); clear irregular boundary. (0 to 15 inches thick)
C--48 to 72 inches; pale brown (10YR 6/3) gravelly loamy coarse sand, brown (10YR 4/3) moist; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine and fine roots; few very fine and fine irregular and tubular pores; common fine distinct brown (7.5YR 4/4) moist Fe masses in lower part; 15 percent fine gravel; neutral (pH 7.0).
TYPE LOCATION: Boise County, Idaho; about 3 miles northeast of Horseshoe Bend; 1,200 feet north and 2,600 feet west of the southeast corner of section 12, T.7 N., R.2 E.; USGS Horseshoe Bend Quadrangle; Latitude - 43 degrees, 57 minutes, 15 seconds N. and Longitude - 116 degrees, 09 minutes, 58 seconds W.; NAD 83.
RANGE IN CHARACTERISTICS:
Mollic epipedon thickness - 24 to 48 inches
Depth to redoximorphic features - 40 to 72 inches
Reaction - slightly acid or neutral
Particle-size control section - 5 to 25 percent rock fragments; 10 to 18 percent clay
Moisture control section - moist less than 90 consecutive days when the soil temperature is greater than 47 degrees F.
Average annual soil temperature - 51 to 53 degrees F.
Ap or A horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 1 or 2 dry or moist
Rock fragments - 0 to 15 percent (mostly fine gravel)
Bw horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Texture - L or SL
Clay content - 10 to 18 percent
Rock fragments - 5 to 25 percent (mostly fine gravel)
C horizon
Hue - 2.5Y or 10YR
Value - 5 or 6 dry, 3 or 4 moist
Chroma - 3 or 4 dry or moist
Texture - COSL or LCOS
Clay content - 4 to 12 percent
Rock fragments - 10 to 35 percent gravel, 0 to 5 percent cobbles and 10 to 35 percent total
COMPETING SERIES: These are the Coxlake, Deerspring, Endersby, Evans, Flofeather, Lapwai, Leavenworth, Narcisse, Okanogan, Patit Creek, Pleasant View, Plinco, Poween, Redola, Threecreeks, and Tombeall series. Coxlake soils have redoximorphic features at a depth of less than 30 inches. Deerspring soils do not have Bw horizons and have a xeric soil moisture regime. Endersby soils slightly or moderately alkaline in the lower part and have a xeric soil moisture regime. Evans soils do not have rock fragments in the control section and have a xeric soil moisture regime. Flofeather soils are somewhat excessively drained and do not have redoximorphic features. Lapwai soils are well drained and have calcareous horizons with secondary carbonates at a depth of 30 to 40 inches. Leavenworth soils do not have Bw horizons and have a xeric soil moisture regime. Narcisse soils have redoximorphic features above 40 inches, do not have Bw horizons, and have a xeric soil moisture regime. Okanogan soils are well drained, do not have Bw horizons, and have a xeric bordering on aridic soil moisture regime. Patit Creek soils have horizons with more than 35 percent rock fragments and have a xeric soil moisture regime. Pleasent View soils have calcareous horizons and have a xeric soil moisture regime. Plinco soils do not have Bw horizons and combined thickness of the A horizons is greater than 40 inches. Poween soils are moderately or strongly alkaline throughout and have a xeric soil moisture regime. Redola soils are calcareous throughout and are slightly or moderately alkaline. Threecreeks soils have a 20 to 24 inch thick mollic epipedon, a lithologic discontinuity at a depth of 35 to 45 inches and have a xeric soil moisture regime. Tombeall soils have redoximorphic features at a depth of 12 to 30 inches and have average annual soil temperatures of 54 to 56 degrees F.
GEOGRAPHIC SETTING: Porter soils are nearly level or gently sloping on flood plains at elevations of 2,600 to 3,350 feet. Slopes range from 1 to 4 percent. These soils formed in alluvium from igneous rocks and lacustrine deposits. Average annual precipitation ranges from 13 to 16 inches. Average annual temperature ranges from 49 to 51 degrees F. Frost-free period is 130 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Jasseek, Piercepark and Shawmount soils. These soils have argillic horizons. Jasseek soils are on relict lake terraces. Piercepark and Shawmount soils are on fan remnants.
DRAINAGE AND PERMEABILITY: Moderately well drained with a high water table at 40 to 60 inches below the soil surface at some time during April and May; very slow or slow runoff; moderately rapid permeability. Porter soils are subject to rare flooding for brief periods in December through May.
USE AND VEGETATION: Porter soils are used mainly for irrigated hayland/pasture. Some areas are used for rangeland or homesites. Native vegetation is basin big sagebrush and basin wildrye.
DISTRIBUTION AND EXTENT: West-central Idaho. MLRA 10 and 11. Porter soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Boise County Area, Idaho, Parts of Ada and Boise Counties, 2005.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Mollic epipedon - zone 0 to 48 inches (Ap1, Ap2, A3, Bw and BC horizons)
Particle-size control section - zone 10 to 40 inches
Soil moisture regime - aridic bordering on xeric
These soils are drier than other Xerolls in the region under similar precipitation due to early runoff and extended period of high evapotranspiration.