The contribution of karstic rocks to soil quality, Ioannina plain (Epirus, Hellas)

• Quality of soil in the plain NW of Ioannina, in relation to the occurrence of karst limestone rocks
• Influence of karstification on the spatial distribution of CaCO3, water soluble and exchangeable Ca2 +, CEC and pH
• Influence of CaCO3 and water-soluble Ca2 + on soil quality
• Influence of CEC, exchangeable Ca2 + and Mg2 +, and pH on soil quality

Soil is a significant link to the food chain as trace elements and compounds are provided, directly or indirectly, to plants, animals and people. In certain areas, soil quality depends mainly on karstic rocks, such as limestone and dolomite, on which a certain type of ecosystem (karst ecosystem), is developed.Ioannina plateau in NW Hellas constitutes a large karstic basin. According to the analytical results of 112 soil samples from the plain to the north-west of the city of Ioannina, a 100 km2 area, which is part of the same karstic system (polje) there is a sufficient amount of samples with over 4% of CaCO3 in about 23.20% of the sampled area. The highest values of CaCO3, water extractable and exchangeable Ca2 + and Mg2 + cations, bicarbonate (HCO3−), Cation Exchange Capacity (CEC), and pH are observed specifically in a NW–SE trending zone near to the foothills of the limestone of Mitsikeli mountain. This is mainly due to the higher supply of material, derived from the dissolution of carbonate rocks, transportation and deposition of CaCO3 of soil originating from the Mitsikeli mountain. The foothills of Mitsikeli mountain are enriched in the detritus derived from the weathering of limestone, and subsequent fluvial erosion and deposition of the calcium carbonate detritus downstream. The transport capacity of the many streams, that drain the slopes of Mitsikeli mountain, is increased, because the inclination is up to 30° and, therefore, with concurrent increase in the supply of such sediments in the eastern part of the Ioannina polje. Thus, the quality of soil in this NW–SE trending zone is definitely improved, mainly because of the supply of calcium carbonate from the aforementioned karst structure, resulting in the development of good quality soil for agricultural use and, consequently, in the development of karst ecosystem.