The Formation of Clay-Enriched Horizons by Lessivage

Salvatore Calabrese, Daniel D. Richter, Amilcare Michele M. Porporato

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Soils with argillic horizons comprise more than 25% of the Earth's surface. Although their origin is still debated, lessivage is often invoked to explain them, but the long timescales involved hinder its direct experimental verification. We present a parsimonious model of clay transport, formulated for long timescales over which lessivage is modeled stochastically, complemented by detailed field observations. This probabilistic description allows us to predict the clay profile, the depth of the Bt horizon from the surface, and the mean clay residence time. The results are tested with field measurements at different locations in the Calhoun Critical Zone Observatory. Dimensional analysis unveils two dimensionless parameters governing lessivage dynamics, leading to a classification based on erosion rates and lessivage characteristics. We identify static and eluviated regimes, in which erosion or eluviation prevails, and an illuviated regime, in which the balance between lessivage and erosion brings about the formation of a Bt horizon.

Original languageEnglish (US)
Pages (from-to)7588-7595
Number of pages8
JournalGeophysical Research Letters
Issue number15
StatePublished - Aug 16 2018

All Science Journal Classification (ASJC) codes

  • Geophysics
  • General Earth and Planetary Sciences


  • Bt horizon
  • clay profiles classification
  • clay translocation
  • formation of clay-enriched horizons
  • lessivage model


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