T. Tóth, D. Kovács, L. Kuti, I. Fórizs, S. Kabos, A. Douaik. 2005. Factors affecting soil salinization in a
sodic grassland. Proceedings of a workshop organized in the frame of the bilateral scientific and technological
cooperation between Flanders and Hungary. ISBN: 90-5989-097-3, (Ghent, 8-9 December 2005).

Abstract

During seven years the spatial and temporal changes of a plot in the most characteristic sodic (solonetzic)
landscape of Hortobágy, Hungary were studied with repeated observations of soil ECa and groundwater depth and
composition. The soil EC showed large fluctuation in subsequent years. There were large changes  in the average
salinity, but EC also changed in a spatially variable manner. Groundwater depth was closely related to the
precipitation and could be predicted precisely based on 10-day sums of precipitation. Based on the ratio of bromide
to chloride ions in the three profiles studied, the Haplic Solonetz (HS) lying in the deepest area showed free
mixture of precipitation and groundwater. The Salic Solonetz (SS) lying in intermediate elevational position, and
Mollic Solonetz (MS) from the higher lying zone showed strong evaporation. The stable isotope composition helped to
interpret the importance of regional groundwater flow in the salinization of the soils. Largest evaporation and
infiltration of precipitation could be found at the HS profile, but at the SS and MS profiles evaporation was the
dominant process. Smallest infiltration of precipitation was inferred at the SS profile. Based on the data a
conceptual model of soil salinization has been compiled based on the contrastive water regime of warm, dry and
rainy periods. Most important factors in this model are elevation, plant cover of surface, surface soil temperature
and soil hydraulic conductivity, and the seasonally changing direction of groundwater movement.