Soil Processes and Salt Dynamics in Dune Soils

In Chapter 5 (this volume), we described the soil pattern and characteristics of the sand dune ecosystem of Nizzana. In the following, we will reconstruct the formation of the main soils, their weathering and brownification, their aggregation and crust formation, their humus accumulation and carbonate accumulation being some of the main soil processes. However, our special interest will be on the salt dynamics of the soils. The sand dune ecosystem of Nizzana is influenced by the atmospheric deposition of soluble salts and carbonates (see Chap. 19, this volume). While carbonates derive mainly from exposed limestones of the adjacent mountainous areas, dissolved ions from sea spray are transported by north-westerly winds from the Mediterranean and precipitated through rainfall (Eriksson 1958). Yaalon (1964) estimated annual deposition of up to 100 kg km−2 of marine-borne salts, with a decreasing gradient from the coast inlands. For the Nizzana ecosystem, Littmann and Gintz (2000) reported annual deposition rates of dissolved ions in the range of 800–1,000 kg km−2, calculated from deposition experiments in 1997 and 1998, while Yair et al. (1991) determined an annual salt deposition at Sede Boqer in the range of 800 kg km−2. During evaporation of the soil solution, different salt species are precipitated according to the concentration and composition of ions and the solubility product of the salts. In Nizzana, the limited rainfall of the arid climate is insufficient to leach soluble salts and carbonates from the soils, hence leading to their accumulation. Deposition of carbonates and soluble salts by dust and rainfall, as well as the redistribution of soluble elements by surface runoff and migration of soil solutions influence the spatial distribution of soil types and vegetation cover by affecting salinization and carbonatization.