LOCATION WILLOWS CA
Established Series
Rev. WFA/MAM/WBS/MAV/JJJ/SBS/AEC
03/2018
WILLOWS SERIES
The Willows series consists of very deep, poorly to very poorly drained sodic soils formed in alluvium from mixed rock sources. Willows soils are in flood basins. Slope ranges from 0 to 2 percent. The mean annual precipitation is about 16 inches and the mean annual temperature is about 60 degrees F.
TAXONOMIC CLASS: Fine, smectitic, thermic Sodic Endoaquerts
TYPICAL PEDON: Willows clay - on an east facing slope of less than l percent in a rice field at 22 feet elevation. (Colors are for dry soil unless otherwise noted.)
Apg--0 to 4 inches (0 to 10 cm); gray (5Y 5/1) clay, very dark gray (5Y 3/1) moist; many fine prominent strong brown (7.5YR 5/6) mottles, yellowish brown (10YR 5/6) moist; granular structure; extremely hard, very firm, sticky and very plastic; common very fine roots; many very fine pores; neutral (pH 6.6); abrupt smooth boundary. (2 to 10 inches thick)
Bssg--4 to 13 inches (10 to 33 cm); gray (5Y 5/1) clay, very dark gray (5Y 3/1) moist; many fine prominent strong brown (7.5YR 5/6) mottles, yellowish brown (10YR 5/6) moist; strong very coarse prismatic structure; extremely hard, very firm, sticky and very plastic; many fine roots; few very fine pores; many prominent intersecting slickensides; neutral (pH 6.7); clear smooth boundary. (3 to 10 inches thick)
Bknssg--13 to 28 inches (33 to 71 cm); olive gray (5Y 4/2) clay, very dark gray (5Y 3/1) moist; strong very coarse prismatic structure; very hard, very firm, sticky and very plastic; common fine roots; many very fine pores; many prominent intersecting slickensides; slightly effervescent with segregated lime in soft masses; moderately alkaline (pH 8.4); diffuse boundary. (10 to 20 inches thick)
Bnssg1--28 to 38 inches (71 to 97 cm); olive gray (5Y 4/2) clay, very dark gray (5Y 3/1) moist; strong coarse prismatic structure; very hard, very firm, sticky and very plastic; few fine roots; many very fine and few fine pores; many prominent intersecting slickensides; slightly effervescent with disseminated lime; strongly alkaline (pH 8.7); clear smooth boundary. (8 to 20 inches thick)
Bnssg2--38 to 48 inches (97 to 122 cm); olive gray (5Y 5/2) clay, olive gray (5Y 4/2) moist; moderate coarse prismatic structure; very hard, very firm, sticky and very plastic; few fine roots; many very fine pores; many prominent intersecting slickensides; strongly effervescent with disseminated lime; strongly alkaline (pH 8.5); diffuse wavy boundary. (4 to 13 inches thick)
Bnssg3--48 to 61 inches (122 to 155 cm); olive gray (5Y 5/2) silty clay, olive gray (5Y 4/2) moist; moderate coarse prismatic structure; hard, very firm, sticky and very plastic; many very fine pores; many prominent intersecting slickensides; slightly effervescent with disseminated lime; strongly alkaline (pH 8.8); diffuse wavy boundary. (10 to 15 inches thick)
Bnssg4--61 to 72 inches (155 to 183 cm); olive gray (5Y 5/2) silty clay, olive gray (5Y 4/2) moist; weak medium prismatic structure; hard, very firm, sticky and very plastic; many very fine pores; many prominent intersecting slickensides; slightly effervescent with disseminated lime; strongly alkaline (pH 8.6).
TYPE LOCATION: Yolo County, California; about 3.25 miles east of Woodland; 1320 feet east and north of the SW corner of section 31, T.1O N, R.3 E, MDB&M. Grays Bend Quadrangle. 38 degrees 39 minutes 57 seconds North, 121 degrees 41 minutes 14 seconds West, NAD83
RANGE IN CHARACTERISTICS: The mean annual soil temperature is about 60 degrees to 62 degrees F. The soils have cracks more than 1mm. wide to a depth of 20 inches or more and the cracks remain open through summer and autumn (unless irrigated) and are closed during winter and spring. Some or all of the lower part of the A horizon has slickensides that intersect and the upper part of some Bk horizons have slickensides. Exchangeable sodium content is greater than 15 percent within 40 inches of the surface.
The Apg and Bssg horizons have dry colors of 10YR 6/2, 6/1, 5/2 5/1, 4/1; N5/0, N4/0; 5Y 5/1, 4/1 or 4/2; 2.5Y 5/2, 4/2. Moist colors are 10YR 3/2, 3/1; N3/0; 5Y 3/1; 2.5Y 3/2, 3/1. Some part of or all of the Apg horizon has distinct or prominent mottles. The Apg horizon ranges from clay to silty clay. The uppermost part of the Apg horizon usually has granular or fine blocky structure; the remainder of the Apg horizon and Bssg usually have weak to strong coarse prismatic structure or weak to moderate coarse blocky structure. The Apg horizon is slightly acid to very strongly alkaline and except where the soil has been plowed and mixed is least acid at the surface and increases sharply as depth increases. The lower part has exchangeable sodium of more than 15 percent.
The Bknssg horizons have dry color of 10YR 6/4, 6/3, 5/4, 5/3; 2.5Y 6/2, 5/2; N6/0, N5/0; 5Y 6/4, 6/3, 6/2, 6/1, 5/2, 5/1 or 4/2; 2.5Y 6/4. Moist colors are 10YR 4/4, 4/3, 3/4, 3/3; 2.5Y 4/4, 4/2, 3/2; N4/0, N3/0; 5Y 4/2, 4/1, 3/2 or 3/1. Some part of the Bknssg horizons usually contains distinct or prominent mottles but they may be lacking where the soil has olive colors. The Bknssg horizons are clay or silty clay to a depth of 40 inches or more. Reaction is usually strongly alkaline and the pH ranges from a little less than 8.5 to a little more than 9.0. Exchangeable sodium is more than 15 percent. All parts are weakly to strongly calcareous and usually calcium carbonate concretions are in the upper part. Gypsum or salt crystals or both are common.
The Bnssg horizons have similar colors and textures as the Bknssg horizons and may be lacking in some pedons.
COMPETING SERIES: These are the
Clear Lake,
Hildreth,
Jacktone,
Maxwell and
Subaco soils. Clear Lake soils lack exchangeable sodium in the 10 to 40 inch zone. Hildreth soils are somewhat poorly drained and lack any exchangeable sodium in the profile. They are commonly found in intermittent drainageways. Jacktone soils have a duripan between 20 to 40 inches. Maxwell soils have a Calcium-Magnesium ratio of 2:1 or less. Subaco soils are underlain by siltstone at depths of 20 to 40 inches.
GEOGRAPHIC SETTING: Willows soils are in nearly level flood basins in intermountain valleys and large valleys at elevations of 20 feet to as much as 1,700 feet. The soils formed in fine-textured mixed alluvium. The climate is dry subhumid mesothermal with hot dry summers and cool moist winters. Mean annual precipitation ranges from 10 to 25 inches. Average January temperature is about 45 degrees F., average July temperature is about 78 degrees F., mean annual temperature is about 58 degrees to 62 degrees F; and the frost-free season is about 210 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: Willows soils are in the same general area as the competing
Clear Lake series and the
Capay,
Sacramento and
Riz series. Capay soils have a chroma of 2 or more throughout. Sacramento soils lack sodium in the 10 to 40 inch zone. Riz soils are on slightly higher benches above the Willows soils and have natric horizons.
DRAINAGE AND PERMEABILITY: Poorly drained; runoff is slow; permeability is very slow. Intermittent water tables are at depths of 24 to 60 inches. In some areas the water tables have been lowered by drainage and water control structures. Unless protected this soil receives runoff from other areas.
USE AND VEGETATION: The soil is used for growing rice, sugar beets and safflower. Original vegetation was saline-sodic tolerant plants.
DISTRIBUTION AND EXTENT: On the west side of the Sacramento and San Joaquin Valleys and intermountain valleys of the Coast Range, California. The soils are moderately extensive in MLRA-17, 14 and 19.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Colusa Area, California, 1907.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 13 inches (33 cm)
Slickensides - 4 to 72 inches (10 to 183 cm)
Secondary carbonates - 13 to 28 inches (33 to 71 cm)
SAR greater than 13 - 13 to 72 inches (33 to 183 cm)
Edits made after sdjr project, lab data from S1964CA113015 was incorporated - AEC
ADDITIONAL DATA: This soil was sampled in a trench in Colusa County, CA. NSSL Pedon Nos. 94P-057, 058, 059, 060, 061, S93CA-011-006 through 009. Location: 39 degrees North latitude, 12 minutes, 35 seconds, 122 degrees West longitude, 3 minutes, 53 seconds. Two pedons in Yolo County: NSSL Pedons S64CA-113-015 (this OSD profile), S64CA-113-014.
Series reclassified on May 1996. Competing series not reviewed at that time.
National Cooperative Soil Survey
U.S.A.