New insights into the origin and evolution of glossic features in coarse‐textured soils in northern lower Michigan (USA)

Abstract

Although glossic horizons are widespread throughout the Great Lakes region (USA), any type of detailed empirical investigation of their genesis has not been conducted for decades. In this study, we investigated a well‐drained Haplic Glossudalf formed in calcareous till in northern Michigan and examined its glossic features across five stages of development, from nondegraded to completely degraded. Along this sequence, the glossic horizon is formed from a Bt horizon, then destroyed, evolving into an E horizon. Argillic horizon degradation is initiated from the top downward, along discrete percolation pathways. Here, temporary, highly localized, anoxic conditions favor the reduction and eluviation of Fe oxides associated with argillans. After Fe removal, clay, and to lesser extent fine silt, in the argillans become mobilized. This process results in bleached, E horizon interfingerings that penetrate the upper Bt horizon. Although eluviation of clay and fine silt is required for glossic horizon formation, their removal follows a distinct pathway from fine clay through coarse clay, and finally fine silt. This research documents the importance of redox processes at microsites in the upper Bt horizon as the destabilizing trigger for glossic horizon formation. Redox processes and microerosion may be more important than the traditionally accepted view of destabilization of clay floccules by loss of basic cations from the exchange complex. We also note that lessivage, as traditionally defined, in these soils is associated with not just clay translocation, but also fine silt.

Using Fixed-Potential Electrodes To Quantify Iron And Manganese Redox Cycling In Upland Soils

“…Our results add to the growing literature documenting anaerobic respiration in upland soils that are not saturated with the frequency that was once thought to be necessary for metal reduction (Hall et al 2016;Barcellos et al 2018b;Baish and Schaetzl 2021). Anaerobic respiration has long been regarded as potentially important in upland soils (e.g., Sexstone and Parkin 1985;Parkin 1987;Zausig et al 1993;Lee et al 1999;Verchot et al 2000), but our results are the first, to our knowledge, to measure in situ rates of anaerobic respiration with Fe and Mn as a terminal electron acceptor within uplands.…”

Loess formation and chronology at the Palaeolithic key site Rheindahlen, Lower Rhine Embayment, Germany

“…Especially the Rheindahlen Soil shows increased contents of clay and fine silt. Both grain size fractions can be affected by illuviation (Baish and Schaetzl, 2021). The next sedimentary unit starts with the Rheindahlen Humus Zone and shows increasing GSI values up to the lower boundary of the Erkelenz Bt.…”

“…Equivalent doses were calculated with an arithmetic mean. Fading tests (Auclair et al, 2003) were carried out for all samples for the IR 50 measurement protocol. IR 50 data were corrected for fading if g values exceeded 1 % per decade (Buylaert et al, 2012), following the approach of Kars et al (2008) which is based on the work of Huntley (2006).…”