Established Series


The Saco series consists of very deep, very poorly drained soils formed in silty alluvial deposits. They are nearly level soils on flood plains, subject to frequent flooding. Slope ranges from 0 to 2 percent. Permeability is moderate in the silty layers and rapid or very rapid in the underlying sandy materials. Mean annual temperature is about 50 degrees F. and mean annual precipitation is about 47 inches.

TAXONOMIC CLASS: Coarse-silty, mixed, active, nonacid, mesic Fluvaquentic Humaquepts

TYPICAL PEDON: Saco silt loam - grass field. (Colors are for moist soil unless otherwise noted.)

A--0 to 12 inches; very dark gray (10YR 3/1) silt loam; gray (10YR 5/1) dry; weak coarse granular structure; very friable; many fine roots; moderately acid; clear wavy boundary. (10 to 15 inches thick)

Cg1--12 to 32 inches; gray (10YR 5/1) silt loam; massive; friable; few fine roots; common medium faint light brownish gray (10YR 6/2) iron depletions and common medium prominent strong brown (7.5YR 5/8) masses of iron accumulation; moderately acid; clear wavy boundary.

Cg2--32 to 48 inches; gray (5Y 5/1) silt loam with thin strata of very dark gray (10YR 3/1) silt loam; massive; friable; moderately acid; clear wavy boundary. (Combined thickness of the silty C horizon layers is 30 to 50 inches)

2Cg3--48 to 60 inches; gray (10YR 6/1 and 5/1) stratified coarse sand and medium sand; single grain; loose; moderately acid.

TYPE LOCATION: Hartford County, Connecticut; town of South Windsor, 1200 feet west along Newbury Road from the intersection with Ter Street and 270 feet south of Newbury Road. USGS Manchester quadrangle; latitude 41 degrees 49 minutes 49 seconds N., Longitude 72 degrees 37 minutes 23 seconds W., NAD 27.

RANGE IN CHARACTERISTICS: Depth to the coarse-textured substratum layers is more than 40 inches. Gravel ranges from 0 to 5 percent to 40 inches and from 0 to 40 percent below. The soil is strongly acid to neutral to a depth of about 30 inches and moderately acid to neutral below.

Some pedons have O horizons up to 5 inches thick.

The A or Ap horizon has hue of 7.5YR through 2.5Y, value of 2 or 3 and chroma of 1 through 3. Texture is silt loam, mucky silt loam, very fine sandy loam or mucky very fine sandy loam. It has weak granular structure or the horizon is massive. Consistence is friable or very friable.

Individual layers of the C horizon are neutral or have hue of 10YR through 5Y, value of 3 through 6 and chroma of 0 through 2. Layers within a 30 inch depth commonly have value of 5 or 6 and chroma of 1 or 2 and have redoximorphic features. Included in some pedons are thin, Ab horizon strata. Texture of the C horizon to a depth of 40 inches or more is silt loam or very fine sandy loam. Below 40 inches texture ranges to include loamy fine sand through very gravelly coarse sand. Some pedons have subhorizons with texture of fine sandy loam. The upper silty layers are massive or have weak structure. Consistence is friable or very friable. The underlying sandy layers are single grain and loose. The thickness and number of horizons below the A horizon is variable and corresponds to the thickness and variability of the alluvial deposits.

COMPETING SERIES: There are no other series currently in the same family.

The Birdsall, Mansfield, Rippowam, Wayland and Whitman soils are similar soils in related families.

Birdsall, Mansfield and Whitman soils have a regular decrease in organic-carbon with depth. In addition, Mansfield and Whitman soils are coarse-loamy. Wayland soils have a dark A horizon less than 10 inches thick and are fine-silty. Rippowam soils are coarse-loamy and poorly drained.

GEOGRAPHIC SETTING: Saco soils are nearly level soils on flood plains, along rivers and streams. They are in depressed areas. Slope ranges from 0 to 2 percent. The soils formed in recent silty alluvium derived mostly from granite, gneiss, schist, shale and sandstone. Mean annual temperature is 45 to 54 degrees F., mean annual precipitation is 32 to 50 inches and the growing season is 120 to 195 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Agawam, Bash, Enfield, Hadley, Haven, Hinckley, Limerick, Merrimac, Ninigret, Occum, Pootatuck, Rippowam, Suncook, Tisbury, Windsor and Winooski soils on nearby landscapes. The well drained Hadley, moderately well drained Winooski and poorly drained Limerick soils are associated in a drainage sequence. Agawam, Enfield, Haven, Hinckley, Merrimac, Ninigret, Tisbury, and Windsor soils are better drained soils on nearby outwash terraces. Bash, Occum, Pootatuck and Suncook soils are coarser textured flood plain associates.

DRAINAGE AND PERMEABILITY: Very poorly drained. Surface runoff is slow or very slow. In places water is ponded on the surface from late fall through early spring. Permeability is moderate in the silty layers and rapid or very rapid in the underlying sandy materials. These soils flood in the spring and after periods of heavy rainfall.

USE AND VEGETATION: Most areas are in brushy woodland. Common trees are red maple, elm, willow, pin oak, and alder. Fir and spruce are common in the northern areas. A few areas are in low quality pasture.

DISTRIBUTION AND EXTENT: Floodplains in Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, Vermont and eastern New York; MLRAs 101, 142, 144A, and 145. The series is of moderate extent.


SERIES ESTABLISHED: Cumberland County, Maine, 1915.

REMARKS: This revision reflects change in soil taxonomy and general updating. Cation exchange activity class placement determined from a review of limited lab data and similar or associated soils. Saco soils were previously used in Maine but soil temperature studies have resulted in the mesic soil temperature regime not being used currently.

Diagnostic horizons and features recognized in this pedon are:

1. Umbric epipedon - the zone from 0 to 12 inches (A);
2. Fluvaquentic subgroup - an irregular decrease in organic-carbon content between a depth of 25 cm. and 125 cm. and slope less than 25 percent;
3. Particle size class - averages coarse-silty in the control section 10 to 40 inches.

National Cooperative Soil Survey