Soils

Soils in the area are predominantly moderately well-drained silt loams derived from weathered limestone, schist, gneiss, and quartzite. Considerable portions of the soils within the park are categorized as Class I or Class II soils for agriculture. Class I soils have few limitations that restrict use, while Class II soils have moderate limitations which may impact the selection of plants.

According to the soil survey of Montgomery County (U.S. Department of Agriculture Soil Conservation Service [USDA-SCS] 1967), the primary soil south of the Schuylkill River is Duffield silt loam. This soil type extends from Valley Forge NHP to Willow Grove, PA. Erosion hazards range from moderate to severe in this series. The soil offers few limitations for residential development and supports general farming activities as well. If the soil were used intensively for septic tank release, the groundwater could be contaminated.

The dominant soils southwest of the Schuylkill River are Edgemont Channery loam and Edgemont very stony loam. Both are scattered throughout a band stretching from Valley Forge to west of Bryn Athyn, PA. Erosion hazards range from moderate to severe within these soils. Due to the high rock content and steep slopes, these soils have limited development possibilities. They are, however, able to support a number of general farming activities including field crops, fruit, and pasture (USDA-SCS 1967).

The dominant soils north of the Schuylkill River are varied and include Penn-Lansdale sandy loams: These soils have moderately rapid permeability and low to moderate moisture capacity. Erosion hazards in this series range from moderate to severe. The soil is capable of supporting general farming activities (planting), which in turn can protect the soil from erosion hazards.

Lawrenceville silt loam: Permeability is moderately slow through the subsoil, thus impeding water movement and root development. Erosion hazards are severe and development may be hindered due to erosion from poor permeability.

Birdsboro silt loam: Generally these soils are moderately permeable with a high level of moisture availability. These conditions provide it with few limitations for farming uses. Erosion hazards range from slight to severe, depending on the slope. Development has few limitations as well; however, in some small areas permeability is slow and a high water tables exists.

Readington silt loam: Permeability is moderately slow, and the level of moisture availability is moderate to high. Erosion hazards range from slight to severe, depending on the slope. The soil varies in acidity but is well suited for planting. Development is possible; however, it is limited by slow permeability and a seasonally high water table.

Bowmansville silt loam: This soil is poorly drained and typically found within floodplains. Floodplain regions have limited development possibilities but are valuable when retained as open space, bird sanctuaries, or wildlife habitats (USDA-SCS 1967).

Hydric Soils

Hydric soils typically support the growth and regeneration of wetland vegetation and are thus important in determining the potential location of jurisdictional wetlands1. By definition, “a hydric soil is a soil that is saturated, flooded, or ponded long enough during the growing season to develop anaerobic conditions in the upper part” (USDA 1991). The only soils designated by the USDA as hydric within Valley Forge NHP are Bowmansville silt loam and Readington silt loam.

The Bowmansville soils are located in small pockets north of the Schuylkill River, while the Readington soils are spread out across the north side of the park. Small pockets of Readington soils also exist along the southern shore of the Schuylkill River.

Prime Farmland Soils

Prime farmland is one of several designations made by the USDA to identify important farmland in the United States, which contribute to the nation’s short-and- long-range needs for food and fiber. In general, prime farmland has an adequate and dependable water supply from precipitation or irrigation, a favorable temperature and growing season, an acceptable level of acidity or alkalinity, an acceptable content of salt or sodium, few to no rocks, and permeable soils (designated as prime farmland soils by the USDA).

Prime farmland soils can be used for crops, pasture, or woodlands but are still considered prime farmland soils. Within Valley Forge NHP, prime farmland soils include Edgemont channery loam, Penn silt loam, Penn-Landsdale complex, Birdsboro silt loam, and Readington silt loam.

The Edgemont soils are located primarily west of Valley Creek. These soils are also scattered along the western shore of the Schuylkill River. The Penn silt loam and Penn-Landsdale complex are also located along the southern shore of the Schuylkill River, but also exist in numerous locations north of the river as well. The Birdsboro soils are also located north of the Schuylkill River. Finally, the Readington silt loams are located in numerous locations north of the Schuylkill River, with a few small pockets located along the river’s southern shore.