Yolo series (Mapunits:  181, 182)

The Yolo series consists of well drained soils on alluvial fans. Slope is 0 to 5 percent. Elevation ranges from near sea level to 500 feet. These soils formed from recent alluvium. The vegetation consists mostly of vineyards and small areas of pasture and prune orchards. The mean annual precipitation is 25 to 40 inches, and the mean annual temperature is 59° to 62° F. Summers are hot and dry, and winters cool and moist. The frost-free season is 220 to 260 days.

In a representative profile the surface layer is dark grayish brown, neutral loam and silt loam 24 inches thick. The underlying material is dark grayish brown and brown, neutral silt loam to a depth of 60 inches or more.

Permeability is moderate. The effective rooting depth is 60 inches or more. Available water capacity is 10 to 12 inches.

Yolo soils are used for vineyards, orchards, and pasture.

Representative profile of Yolo loam, 0 to 2 percent slopes, 50 feet east of Napa River and 100 feet south of Oakville Cross Road, NW¼SE¼ sec. 22, R. 5 W., T. 7 N.:

Ap-0 to 6 inches, dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; massive; hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many fine and medium tubular and interstitial pores; neutral (pH 6.7); diffuse smooth boundary.

A12-6 to 24 inches, dark grayish brown (10YR 4/2) silt loam, very dark grayish brown (10YR 3/2) moist; massive; extremely hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many fine and medium tubular and interstitial pores; neutral (pH 6.7); diffuse smooth boundary.

C1-24 to 45 inches, dark grayish brown (10YR 4/2) silt loam, dark brown (10YR 3/3) moist; massive; bard, friable, slightly sticky and slightly plastic; few coarse and common fine and medium roots; many fine and medium tubular and interstitial pores; neutral (pH 6.7); diffuse smooth boundary.

C2-45 to 60 inches, brown (10YR 4/3) silt loam, dark brown (10YR 3/3) moist; massive; hard, friable, slightly sticky and slightly plastic; few coarse and common fine and medium roots; many fine and medium tubular and interstitial pores; neutral (pH 6.7).

The A horizon is brown, grayish brown, or dark grayish brown (7.5YR 5/2 and 10YR 4/2, 5/2). Reaction is slightly acid or neutral.

The C horizon is brown, dark grayish brown, or grayish brown (10YR 5/3, 4/3, 5/2, and 4/2) silt loam or silty clay loam. Reaction is slightly acid to mildly alkaline.
 
181-Yolo loam, 0 to 2 percent slopes. This nearly level soil is on alluvial fans. It has the profile described as representative for the series.

Included with this soil in mapping were small areas of Bale, Cole, Cortina, and Pleasanton soils.

Runoff is slow. The hazard of erosion is slight.

This Yolo soil is used for vineyards, orchards, and irrigated pasture. Capability unit I (14).
 
182-Yolo loam, 2 to 5 percent slopes. This gently sloping soil is on alluvial fans.

Included with this soil in mapping were small areas of Bale, Cole, Cortina, and Pleasanton soils.

Runoff is slow. The hazard of erosion is slight.

This soil is used for vineyards, orchards, and irrigated pasture. Capability unit IIe-1 (14).