Tóth, T. and L. Kuti 1999. Geological factors affecting the salinization of the 
Nyírolapos Sample Area (Hortobágy, Hungary). Agrokémia és Talajtan. 48:445-457.

The objective of the paper was to describe the relationship between geological 
factors, such as salt concentration and composition of groundwater, particle 
size of underground layers, elevation and groundwater and soil salt 
concentration. 29 boreholes were made to 10 m depth and nonparametric statistics 
were used for testing relationships between geological factors and soil salt 
concentration. The research area is representative of the spatially variable 
solonetzic grasslands of the Great Hungarian Plain. Inside a small area the 
maximal difference in elevation is 1.76 m, which is accompanied by a similar 
difference in groundwater level. The electric conductivity of groundwater showed 
values between 0.8 and 20 mS/cm in the geological boreholes. The 3 year average 
electrical conductivity of 1:2.5 suspensions from 0-40 cm depths varies between 
0,4 and 3,6 mS/cm. There were eight vegetation types distinguished in the area, 
their distribution reflects the differences in elevation, salinity, and the 
closely related zonation of water regime. The depth of groundwater level and the
composition of groundwater shows relationship to the elevation, their effect is
modified by the geological stratification, and these result in the variable
vegetation cover. The depth distribution of calcite is related to the soil salt
concentration. When the soil salt concentration was predicted by the regression
tree technique, the best predicting variables selected by the algorithm were the
elevation and the particle size of the underground layers. The value of
correlation coefficient was 0.8. According to the observations and analyses, the
soils of the area were formed under the effect of oscillating groundwater level
and the elevation is the dominant factor of the spatial variability of salt 
accumulation.