Origin and Properties of Smectite in Loess‐derived Soils of Western Ohio

Expanding phyllosilicates have been identified in soils of western Ohio for >40 yr, yet little is known about the origin or properties of these clays. The objective of this study was to ascertain the origin of the smectite component of the expanding phyllosilicates from a representative Udalf‐Aqualf‐Aquoll toposequence derived from Peoria loess in western Ohio. The content, distribution, and layer charge of the smectite were evaluated using chemical and x‐ray techniques. Results from these analyses show the smectite present in these soils is a medium‐charge dioctahedral species. Alkylammonium chloride exchange indicated the layer charge of the smectite is between 0.36 and 0.38 mole charge per half unit cell. The smectite generally comprised 50% or more of the total clay content in the B and C horizons of each pedon. The presence of high contents of smectite in the C horizons of all three pedons demonstrates a detrital origin and suggests that Peoria loess was an important source of expanding phyllosilicates in soils of western Ohio.