Argillic Horizon Expression and Classification in the Soils of Two Michigan Hydrosequences

Abstract

AbstractTwo hydrosequences in central Michigan were investigated to evaluate the degree of Bt horizon expression as influenced by the depth and duration of soil saturation. Each hydrosequence was sampled in duplicate and consisted of well or moderately well, somewhat poorly, and poorly drained soils. Total clay ratios, I/E indices (fine clay/total clay of the illuvial zone divided the fine clay/total clay of the eluvial zone), and argillan development were greatest in the well‐drained soils and decreased with decreasing depth to and increasing duration of soil saturation. One of the poorly drained soils lacked Bt horizons while one had Bt horizon expression similar to that of the somewhat poorly drained soils. The water table regimes of all poorly drained soils were similar. The poorly drained soils with Bt horizons contained relatively large amounts of smectite, particularly in the clay films, while those lacking Bt horizons contained virtually no smectite. The Bt horizons developed to a greater degree where moisture fronts penetrated the solum the greater period of the year. Where penetration was retarded by soil saturation, mineralogy contributed to the degree of Bt horizon development.