Soil Genesis of Four Alfisols Established in Oak Hickory Forests along Drainages into the Mississippi River in Southeastern Missouri, USA

Abstract

Alfisols in USA taxonomy are “deciduous forest” soils having an argillic horizon with a base saturation in the control section greater than 35%. Alfisols are geographically extensive and support productive agriculture and deciduous forest ecosystems. Understanding Alfisol genesis, including the presence and intensity of the dominant soil processes, facilitates best management practices that provide stewardship for these soil resources and improves forest and agriculture productivity. Four Alfisols, presently having mature forest settings and located in the central United States along the Mississippi River, were selected for soil and landscape description, classification, and delineation of the dominant soil forming processes. Excavated soils were described and routinely sampled for subsequent physical, chemical, and mineralogical analysis. An aqua regia digestion protocol provided elemental analysis for identifying and inferring the intensity of soil forming processes. The dominant soil forming factors include 1) organic matter accumulation, 2) clay eluviation-illuviation, 3) acidification, 4) base cation accumulation in the A horizons by the forest vegetation, 5) Fe-oxyhydroxide formation, and 6) clay mineral synthesis. Two soils were developed entirely in Peoria loess and two soils were developed in Peoria Loess overlying Ordovician limestone residuum. Ecological site descriptions provide land managers information for evaluating land suitability and the capability to implement different management activities without ecosystem disturbance. Best management practices for the described landforms and based on their Ecological Site Descriptions are presented.