Improving Hydric Soil Identification in Areas Containing Problematic Red Parent Materials: a Nationwide Collaborative Mapping Approach

Abstract

Hydric soil identification utilizes diagnostic morphologic features, including iron transformations, resulting from anaerobic conditions. However, soils derived from some red parent materials (RPM) fail to develop characteristic hydric soils morphologies, confounding hydric soil and wetland delineation. Laboratory and field methods addressing resistant RPM soils exist, but application remains limited by uncertainty regarding problematic RPM distribution. In response, a collaborative effort (>50 participants) documented problematic RPM distribution across the contiguous United States. Specifically, >1100 samples from >450 locations underwent laboratory analysis using the Color Change Propensity Index to identify problematic RPM soils. Geospatial analysis linked verified problematic soils with associated geologic units and soil series, generating maps of RPM distribution. Potential problematic RPM was identified in the Northeast and Mid-Atlantic, Great Lakes, South-central, and Desert Southwest-Western Mountains (problematic RPM regions herein), encompassing diverse groups of soils and parent materials. Despite the observed variability in soil characteristics, results suggest that problematic RPM was consistently derived from sedimentary, hematite-rich red bed formations developed where deposition of terrestrial sediments occurred in near-shore, marginal-marine environments. Understanding problematic RPM soils distribution promotes the appropriate application of existing hydric soil field indicators, including F21 – Red Parent Material, thus improving approaches to hydric soil identification and wetland management.

from Energy Ecology Environment Ambio via Terpsi Hori on Inoreader https://ift.tt/2rvbGPk