Field test for identifying problematic red parent materials

Wetlands are valuable ecosystems protected under Section 404 of the Clean Water Act, and accurate delineation of wetlands is thus important for their continued preservation. The standard method for wetland delineation includes identifying hydric soils based on their distinctive hydromorphology, which often includes gley colors. However, in some cases soil colors can be misleading. One example is hydric soils derived from problematic red parent material (PRPM), which fail to exhibit the dominantly gray colors commonly observed in soils formed under hydric conditions. Recently, the widespread distribution of soils derived from PRPM was tied to red‐bed formations of Mesozoic or Paleozoic age, with deep red colors associated with large hematite crystals. The color change propensity index currently used to test (in the laboratory) for PRPM soils takes many hours and requires specialized expensive equipment, which may substantially delay assessment. The objective of this study was to develop a rapid field test that could be used to recognize soils formed from PRPM. The proposed field test and calculated One Hour Color Index can be used to determine if soils are derived from PRPM with 90% accuracy, using easily accessible chemicals and equipment (sodium dithionite, sodium chloride, distilled water, plastic test tubes) and a Munsell color book.