Fragipan Soils of Illinois: I. General Characterization and Field Relationships of Hosmer Silt Loam

Bisequal soils with fragipans are common in southern Illinois. The purpose of this introductory paper is to set the general framework for understanding the nature and occurrence of these soils through the description of the morphology, chemical and physical properties, and field relationships of Hosmer silt loam, a soil with moderate fragipan expression. The bisequal nature and expression of the fragipan increase with decreasing loess thickness and with latitude from north to south. Maximal expression is in the low, moderately well‐drained, topographic positions. It is suggested that these soils in Illinois are part of an interstate sequence extending southward into Mississippi, within the loess‐derived soils of the Mississippi River Valley.