Hydropedology of a coarse-loamy catena in the lower Coastal Plain, NC

The identification of the depth of seasonal saturation in soils is critical for a multitude of land uses including the siting and design of septic systems and delineation of wetlands. Often 2 chroma redox depletions are used to make this determination; however, other redoximorphic features are also related to saturation. With increasing land use intensities and environmental concerns it is important to understand exactly how redoximorphic features (RMFs) relate to saturation. The objective of this research is to relate RMFs to saturation in a coarse-loamy catena in the lower coastal plain in North Carolina. A relatively undisturbed site in eastern NC was identified and three transects were instrumented with recording wells, redox probes and thermocouples. A rain gauge was also located at the site. In all the soils investigated, ≤ 2 chroma redox depletions related to an average cumulative annual saturation percentage (CSP) of 15%. However, the ≤ 2 chroma redox depletions indicated a larger CSP in the MWD soils (19%) as compared to the SWPD soils (11%). This suggests that ≤ 2 chroma redox depletions do not mean the same thing in all soils. Regulations that rely on this single feature may be identifying different degrees of saturation and thus may have a varying implication to wastewater treatment and water quality.