Hyperarid Soils and the Soil Taxonomy

In the past decade, pedological research in hyperarid environments worldwide has revealed landscapes and soil features that are regionally prevalent and distinctive, but not well captured in the current soil taxonomy. Hyperarid soils bear genetic features that can differ considerably from those in more humid desert environments. In particular, they often contain horizons cemented with halite (NaCl) or heavily enriched with nitratine (NaNO 3 ). Unlike soils commonly found in more humid regions, they may also lack most vascular plants, pedogenic carbonates, and biotic mixing processes. Based on the global occurrence of indurated salic horizons and nitric horizons in hyperarid soils, we propose that the soil taxonomy be amended to include a petrosalic diagnostic subsurface horizon, a nitric diagnostic subsurface horizon, and Petrosalids great group within the Aridisols order. Additionally, we suggest the definition and establishment of a Hyperaridic Soil Moisture Regime (SMR). In this paper, we use soils from the Atacama Desert to illustrate how pedogenesis in extreme hyperarid environments differs from that in more humid environments, and we review the current literature regarding soils in other hyperarid locations with indurated soluble salt horizons. The changes proposed here would create a more encompassing classification system for the Earth's desert regions, improving our ability to clearly communicate relevant genetic, ecological, and economic information to both land‐managers and researchers.