Surface samples collected from each soil series were analyzed for organic matter, texture, salinity, and water holding capacity. In addition, selected soils were sampled for complete chemical and physical testing on each layer. Results of these analyses are expected in 1998, and will be made available in future publications.

Laboratory analysis results for organic matter in two anthropogenic (human altered, cut and fill) soils and two natural soils (Fig. 16) demonstrates that natural soils contain more organic matter than the much younger anthropogenic soils. Organic matter builds up slowly in soils over time.

Figure 16. Organic matter is lower in fill topsoil (1 and 2) compared to natural topsoil (3 and 4) because the fill soils are younger, have less vegetation and are often more compacted and eroded than natural soils.

Sandy soils accumulate less organic matter than loamy soils (Fig. 17). Organic matter and clay particles are electrically charged, while sand particles are not. Organic matter is electrically attracted to clay particles in the soil. Sandy soils have little clay and hold little organic matter. Also, sandy soils do not hold as much water as loamier or clayier soils, and so do not produce as much vegetation or contain as much organic matter.

Figure 17. Soils that have more clay and less sand have more organic matter because clay holds more water for plant growth and binds with organic matter, but sand does not. Soil (1) is Manchester loamy sand, (2) is Cheshire loam, (3) is Arnot loam.

Figure 18. As the water table gets nearer the surface the organic matter increases because wet soils have little oxygen for decomposition by microbes. Fredon Silt Loam is in Upland Wetlands, Rippowam Mucky Silt Loam is in Floodplains, Wallkill Mucky Silt Loam is in Freshwater Marshes, and Ipswich Mucky Peat is in Saltwater High Marsh.

The accumulation of organic matter is higher in wetter soils (Fig. 18). Organic matter builds up in soils (usually in wetlands) where large amounts of vegetation matter is added to the soil, and where the microbes are restricted by lack of oxygen or low temperature from decomposing all the vegetation that is added.

The types of soil microorganisms are affected by the amount of soluble salts in the soil. As the soil salinity content increases from floodplain to the marsh soils (Fig. 19), the number of microbes that break down organic matter most effectively are decreased, and the organic matter content increases.

Figure 19. As conditions change from (1) Ipswich in Low Marsh to (2) Ipswich in High Marsh to (3) Wallkill in Freshwater Marsh to (4) Rippowam in Freshwater Floodplain, the soil salinity in the topsoil decreases because of the amount of salts in the water source decreases.

Soils are an important water source for plants. The amount of water available for plants is expressed as available water capacity (AWC). The available water capacity is an estimate of how much water a soil can hold and release for use by plants, measured in inches of water per inch of soil. It is influenced by soil texture, content of rock fragments, depth to a root-restrictive layer, organic matter, and compaction. In general, the more pores, organic matter, and clay a soil has, the more water it can hold. Compacted soils have less pores that noncompacted soils. In Figure 20, the laboratory data demonstrates that Arnot soils have low AWC because they contain a high amount of rock fragments that do not have moisture, and they are shallow to bedrock, which is a barrier to most roots. Sandy Penwood soils hold less available water than loamy Cheshire soils because they have less total porosity, fewer small pores, and less organic matter.

Figure 20. The amount of available water increases from (1) shallow, gravelly loamy Arnot, to (2) deep, sandy Penwood, to (3) deep, loamy Cheshire. Gravel and shallow bedrosk limit the water in (1), and sandy textures limit water in (2).