This module begins with a review of redox reactions and redoximorphic features. Reduction and concurrent oxidation (redox) are the dominant chemical processes taking place in wetland soils. There are abiological and biological driven redox reactions in wetland soils. The module will focus on the reactions driven by microbial breakdown of organic matter in soils under saturated conditions that lead to unique anaerobic conditions that meet the hydric soil definition of USDA. The redox reactions lead to mobilization of soluble Fe and Mn (depletion zones and surfaces) and subsequent reoxidation (concentration zones and surfaces), collectively called redoximorphic features. Redox feature types are identified through images. Description of the features will be briefly reviewed, in preparation for use as components of field indicators of hydric soils.
Target audience: Wetland field practitioners who need expertise in hydric soils and seek to understand how hydric soils are formed and how to recognize and interpret the information they provide when observed in the field.