LOCATION SULA               MT

Established Series
Rev. BHW
04/1999

SULA SERIES

The Sula series includes moderately dark to dark medium textured friable noncalcareous grassland soils in intermountain valleys in the Northern Rocky Mountains. These soils occur in an area of relatively cool summer climate where the mean annual precipitation ranges from 15 to 17 inches and is well distributed throughout the year but is heaviest during summer. Their parent materials consist of light-colored, noncalcareous, silty loess-like material three or more feet thick. This, as a rule, is underlain abruptly by brown or reddish-brown firm or moderately compact gritty clay loam similar to the material giving rise to the Lick (Gray-Wooded) and Charlos* (Chestnut-like) soils. The Sula soils differ from Bozeman soils mainly in having no free carbonate of lime in their solums and from Thunder* soils mainly in having darker colored surface soils.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive Ustic Haplocryolls

TYPICAL PEDON: Sula - silt loam.

0 to 9 inches; dark grayish-brown (See Note 1) (10YR 3/2 moist) silt loam; soft granular or crumb structure; slightly acid. (7 to 12 inches thick)

9 to 12 inches; brown (7.5YR 5/4 moist) heavy silt loam; medium blocky structure; slightly acid. (3 to 6 inches thick)

12 to 22 inches; yellowish-brown (10YR 5/4 moist) heavy silt loam; moderately well developed irregular blocky structure; neutral or slightly acid. (8 to 14 inches thick)

22 to 40 inches; brownish-yellow (10YR 6/6 moist) silt loam or very fine sandy loam; massive or ill-defined irregular blocky structure; about neutral. (16 to 24 inches thick)

40 inches; brown (7.5YR 5/4 moist) gritty clay loam; massive; about neutral. (1 to 5 feet thick)

TYPE LOCATION: Western Montana.

RANGE IN CHARACTERISTICS: These soils are rather uniform throughout most of their distribution. Where the parent materials are thickest the soils may grade into a substratum of fine sandy loam. On some of the nearly flat areas the upper part of the subsoil is moderately heavy and tends toward Solonetz development. In places, these soils are in complex association with thinly developed Solonetz.

GEOGRAPHIC SETTING: Undulating and gently sloping bench remnants of old alluvia fans, terraces or valley-fill deposits.

DRAINAGE AND PERMEABILITY: The soils are well drained; surface run-off is medium; permeability moderate.

USE AND VEGETATION: Native bunch grasses and introduced species. Pasture, dry-land and irrigation farming.

DISTRIBUTION AND EXTENT: Western Montana.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana

SERIES PROPOSED: Tentatively in the Bitterroot Valley Area, Montana, 1947. The name is taken from Sula Basin, a small mountain valley of this name.

REMARKS: Where the soils are developed in silty material ranging from 15 to 30 inches thick underlain by materials of markedly different character, thin solum phases of Sula soils are recognized at present. Where underlying material is calcareous, mapping inclusions will include soils that are calcareous in the lower part of their subsoils.

Note 1: Provisional Soil survey color names based on Munsell Color Charts, adopted in Staff Conference, 1947.

* Tentative series proposed in Bitterroot Valley Area, Montana.

OSED scanned by SSQA. Last revised by state on 6/47.

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National Cooperative Soil Survey
U.S.A.