Salt-Affected Soils and Their Native Vegetation in Hungary

Abstract

Approximately 13% of Hungary is considered to be salt-affected and with this large extent it is unique in Europe. There are large areas of naturally saline and sodic soils, but also secondary salinization is known to occur. Due to the geological and hydrological conditions, the country demonstrates the most characteristic features of natural continental (not marine) salinization, sodification and alkalinization. Since the most important direct source of soil salinization is the shallow groundwater level below the lowland surface, there is a chance of irrigation-related salinization in two dominant situations: when the abundant use of river waters causes waterlogging and rise of saline groundwater (salinization from below); and when typically saline tubewell-waters are used for irrigation (salinization from above). The spatial assessment of salt-affected areas began with the systematic mapping of salt-affected areas. There are a series of ten maps describing different aspects (salt-affected soil types, vegetation types, salt-efflorescences) of the salinity-status nation-wide from 1897 onward, with the latest survey finished last year. Besides the national scale of 1:500,000, soil salinity is also mapped at the scale of 1:100,000 on the “AGROTOPO” map sheets and 1:25,000 in the “Kreybig”-practical soil information (spatial vector data for maps and database for profiles and borings) systems. In spite of the two systems being digitally available, the most detail information collected at the scale of 1:10,000 is available only for 2/3 of the country and is not digitised. Very early maps at field scale, later at regional scale showed numerical salinity/sodicity values. At present field scale numerical maps are analysed in order to optimise salinity mapping in space and time. Parallel to soil studies, the assessment of the vegetation of saline and sodic lands is a traditional topic of Hungarian botanists. The vegetation of these areas is used for millennia by grazing and provides medicine and raw material for several purposes.