The role of rare rainstorms in the formation of calcic soil horizons on alluvial surfaces in extreme deserts

Rivka Amit*, Yehouda Enzel, Tamir Grodek, Onn Crouvi, Naomi Porat, Avner Ayalon

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

Soils in similar geomorphic settings in hyperarid deserts (<50mm yr-1) should have similar characteristics because a negative moisture balance controls their development. However, Reg soils in the hyperarid southern Negev and Namib deserts are distinctly different. Soils developed on stable alluvial surfaces with only direct input of rainfall and dust depend heavily on rainfall characteristics. Annual rainfall amount can be similar (15-30mm), but storm duration can drastically alter Reg soil properties in deserts. The cooler fall/winter and dry hot summers of the southern Negev Desert with a predominance brief (≤1day) rainstorms result in gypsic-saline soils without any calcic soil horizon. Although the Namib Desert receives only 50-60% of the southern Negev annual rainfall, its rainstorm duration is commonly 2-4days. This improves leaching of the top soil under even lower annual rainfall amount and results in weeks-long grass cover. The long-term cumulative effect of these rare rain-grass relationships produces a calcic-gypsic-saline soil. The development of these different kinds of desert soils highlights the importance of daily to seasonal rainfall characteristics in influencing soil-moisture regime in deserts, and has important implications for the use of key desert soil properties as proxies in paleoclimatology.

Original languageAmerican English
Pages (from-to)177-187
Number of pages11
JournalQuaternary Research
Volume74
Issue number2
DOIs
StatePublished - Sep 2010

Bibliographical note

Funding Information:
The research in the Negev was supported by the United States-Israel Binational Science Foundation grant 2006-221 and the U.S. Army Research Office grant ( DAAD19-03-1-0159 ). Our research in Namibia was supported in addition by the U.S.–Israel Cooperative Development Research Program, Bureau for Economic Growth, Agriculture, and Trade, U.S. Agency for International Development (Grant No. C24-26 ). We also were generously assisted by the Gobabeb Research and Training Center and the Desert Research Foundation of Namibia in receiving permits and collecting the soil samples. We thank Dr Mary Seely and Dr Joh Henschel who were particularly helpful. The rainfall data they provided were essential in the understanding the pedologic processes. We particularly thank the editor Alan Gillespie for handling the manuscript and Les McFadden and Bruce Harrison for formal review comments that significantly improved the manuscript. PSD analyses were conducted by A. Lokshin and R. Krasilshikov. Z. Dolgin prepared the OSL samples. Special thanks for Michael Davis for sample preparation and measurements. We are grateful to Bat-Sheva Cohen and Hanna Netzer Cohen for map drawing.

Keywords

  • Calcic soils
  • Carbonate nodules
  • Gypsic-salic soils
  • Namib Desert
  • Negev Desert
  • Oxygen and carbon isotopes
  • Rainfall characteristics

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