Soils of the European Union - European Soil Portal - Europa

4.21 SolonetzesGeographical distributionAreas of Solonetz soils are similar to those of Solonchaks in the European Union, covering nearly 10,000 km 2 (0.24%).However, the geographic extent is somewhat different: Solonetzes are soils of the Charpatian Basin, Romania and Bulgaria.Three units of the Reference Soil Group have coverage with the same order of magnitude (Table 4.21, Figure 4.21).Table 4.21 Area of the second level units of Solonetz soilsUnits in the Reference Soil Groupin the EUCodes ofsoil unitsArea in the EUkm 2Gleyic Solonetz SNgl 2749Haplic Solonetz SNha 2419Mollic Solonetz SNmo 4689Gleyic Solonetzes are characteristic for Romania and are the dominant soils in 13 polygons. (In a further 21 polygons theyare associated and form inclusions in another 12.) Haplic Solonetzes can be found in both on the Great Hungarian Plain(Nagyalföld) and in Bulgaria. They are dominant in 13 mapping units of the latter. Mollic Solonetz is the main type of saltaffected soil in Hungary and it can be found close to the Lake Neusiedl in Austria.47.57%27.89%SNglSNhaSNmo24.54%Figure 4.21 Share of the second level soil units in the area of Solonetz soilsGlobal referenceSolonetz are normally associated with flat lands in a climate with hot, dry summers or with former coastal deposits thatcontain a high proportion of salt. Global coverage of Solonetz soils accounts to approximately 1.35 million km 2 .Solonetz soils are strongly alkaline with subsurface horizon of clay minerals, well developed columnar structure and highproportion of adsorbed sodium and/or magnesium ions. The presence of free soda in soil is associated with alkalinereaction (field-pH > 8.5). Under such conditions, organic matter has a tendency to dissolve and move through the soil bodywith moving soil moisture. The remaining mineral soil material is bleached and in the extreme case a clear eluvial horizonmay form directly over the dense natric subsurface horizon. Black spots of accumulated organic matter can be seen in manySolonetz, at some depth in the natric horizon. The dense natric (clay) illuviation horizon poses an obstacle to waterpercolating downward by the dispersion of soil materials.Land use options of Solonetz soils depend largely on the depth and properties of the surface soil. However, mostSolonetzes are Solonetz are problem soils when used for arable agriculture.Internationally, Solonetz are referred to as alkali soil and sodic soil, Sols sodiques à horizon B et Solonetz solodisés(France), Natrustalfs, Natrustolls, Natrixeralfs, Natrargids or Nadurargids (Soil Taxonomy).52