Tendencies in acidification of soils of hungary [antikvár]

TENDENCIES IN ACIDIFICATION OF SOILS OF HUNGARY Pál Stefanovits - Barbara Simon - Erika Michéli Agricultural University of Gödöllő Acidity status of soil is important for two reasons, on one hand, acidity is one type of soil degradation and on the other hand, it is controlling (in most cases intensifier) soil pollution. The three following factors are mainly responsible for soil acidification: natural acidification, air pollution and fertilizers. Our objective was to examine the proportion of these three factors that are responsible for the current state and change in time of soil acidification. We took soil samples from forested areas next to those profiles that were examined 30-40 years ago. Parallel examination of samples taken from arable land, which were next to the forested area, enabled us to study the differences related to the two types of soil use. Material and Methods A detailed description was given in our previous publication (Stefanovits, 1971) about the description and data of soil profiles for characterizing soil acidity. The presented examinations were carried out on samples from the surface horizons from the locations listed in Table 1,2 and Figure 1. We examined pH(H20), hydrolytic (Yi) and exchangeable acidity (Y2) on the basis of methodology of soil analysis (Búzás, 1988). We determined the aluminum and iron content (Stefanovits, 1955) from the extract of exchangeable acidity of the last sample series in 1997. These data are listed in Table 3. and are illustrated in Figure 2. and 3. Discussion According to the data, between 1955 and 1985 the hydrolytic acidity of soil samples taken from forested area increased significantly. In the next 12 years, the increase with the same rate was only in case of Mátra and Zalaapáti, thus acidity has hardly changed, or even in extreme cases (Hollád and Dömös, Chromic Luvisols), it has decreased on the remaining areas. While the increase can be explained by continuous acid deposition, decrease is probably due to the change of vegetation. In case of Hollád and Dömös (Chromic Luvisols) the forest was spaced out by select cutting, thus the shrub stratum became dense and mainly blackthom, blackberry and hawthorn became dominant. As a consequence, the litter of Austrian vegetation oak vegetation changed to a less acidic litter. In case of Humic Cambisol in