Soil – landscape relationships in the Empordà basin (Catalonia, NE Iberian Peninsula)

Abstract

Soils developed in representative landforms, which were previously mapped at a detailed scale in the Empordà Basin, were selected to characterize their main pedogenetic processes and to improve the soil maps through a better understanding of the soil – landscape relationships. This basin is a relatively large region (1,300 km2) in Northeastern Catalonia, where Neogene and Quaternary sediments outcrop. They are alluvial and delta fan deposits that mainly reflect a continental environment. Besides varying degrees of soil rubefaction, we can identify calcium carbonate redistribution, clay illuviation and sodication as the main soil forming processes, together with abrupt textural changes, vertic and redoximorphic features. These processes and features are expressed under different morphologies in the area, depending not only on parent material, landform and age, but also on human action, which allows us to refine the conceptual soil-landscape model. Calcium carbonate redistribution is a key process reflecting both changing general environmental conditions and local chemical soil conditions. The actual soil characteristics and the soil forming processes allow us to propose that (i) aeolian dust inputs in these soils have been low to moderate throughout, and that (ii) the rainfall pattern in the last part of the Holocene was able to remove these dust inputs, but unable to leach carbonates from medium textured, moderately calcareous soils in the area when they are some kilometres from the sea and not directly affected by the dune system.