Soils of the European Union - European Soil Portal - Europa

4.6 CalcisolsGeographical distributionCalcisols cover less than 10,000 km 2 , only 0.22% of the land surface of the European Union. Calcisols occur in twocountries, being dominant on the islands of Malta and covering about 1.7% of total land area of Spain. The Reference SoilGroup of Calcisol appears 34 times as dominant and 38 cases as associated (with rather high share of 30-50%) within theirpolygons.Two soil units are represented in the European Union from the Calcisol Reference Soil Group, dominated (>95%) byAridic Calcisol. (Table 4.6, Figure 4.6)Table 4.6 Area of the second level units of CalcisolsUnits in the Reference Soil Groupin the EUCodes ofsoil unitsArea in the EUkm 2Aridic Calcisol CLad 8972Haplic Calcisol CLha 317Among the two soil units of the Calcisol Reference Soil Group Aridic Calcisols can be found in Spain, while the Maltesesoils are fall into the Haplic category.3.41%CLadCLha96.59%Global referenceFigure 4.6 Share of the second level soil units in the area of CalcisolsCalcisols are soil with significant accumulation of secondary calcium carbonates, generally developed in dry areas. Soilsbelonging to this Reference Soil Group are common on calcareous parent material in regions with distinct dry seasons, aswell as in dry areas where carbonate-rich groundwater comes near the surface. The total Calcisol area amounts to some 10million km 2 , nearly all of it in the arid and semi-arid (sub)tropics of both hemispheres.Many Calcisols are old soils if counted in years but their development was slowed down by recurrent periods of drought inwhich such important soil forming processes as chemical weathering, accumulation of organic matter and translocation ofclay came to a virtual standstill. However, most Calcisols have substantial movement and accumulation of calciumcarbonatewithin the soil profile. The precipitation may occur as pseudomycelium (root channels filled with fine calcite),nodules or even in continuous layers of soft or hard lime (calcrete).Most Calcisols have a thin (=