Soils with gypsic horizons in southern Sicily, Italy

Information on the geographic distribution and abundance of gypsiferous soils, is required for better management of these soils in the semiarid Mediterranean basin. The alms of this study were to: (i) evaluate the occurrence of the gypsic horizon as influenced by soil-landscape relationships and (ii) classify them for better use and management. Seventeen sites (four soil pedons and thirteen soil augerings), spaced about 12 m apart were surveyed along a slope transect in a Mediterranean semiarid environment in Sicily, Italy. The gypsum content was determined by the thermogravimetric method. Results suggest that these soils, although they did not develop on gypsiferous Substrata, are enriched with secondary gypsum received from a nearby overhanging gypsiferous geological formation. Spatial analysis of gypsum content showed that its presence in the soils exhibit an anisotropic behaviour, strongly depending on local soil morphology and relief. The pedons studied were classified as Gypsic Haploxerepts and Calcic Gypsisols according to the Soil Taxonomy and World Reference Base systems.