Topic 1, Module 1: The five factors of Soil Formation and Horizonation vs. Simple Processes

This module will cover both the five factors of formation and horizonation vs. simple processes. The module presentation will begin 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 session focuses on 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. These 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 is briefly reviewed, in preparation for use as components of field indicators of hydric soils.