Transformational changes after 1989 were primarily caused by major social changes, including those in the economy and agriculture. Slovakia is also affect by globalization processes. The aim of this article is to characterize the changes in agricultural land use and their spatial distribution in relation to the political transformation of society after 1989, using the Dunajská Streda, Levice, Prievidza and Stará Ľubovňa districts as examples. These districts contain all individual agricultural production types in Slovakia. Changes in agricultural land use were analyzed on the basis of the total areas of land use categories for these districts between 1980 and 2010 and for municipal cadastral areas in selected districts between 2000 and 2010. Two basic indicators of changes in land use were selected for this purpose. The first was the percentage increase or decrease in individual land use categories and the second was the dominant processes in land use based on analysis of the main landscape processes. The cumulative surfaces of selected crops and their products were analyzed using a simple continuous diagram depicting the course of harvesting areas between 1980 and 2010. Crop yields were analyzed by linear regression. The tendency for disappearance of agricultural land use was confirmed in the less agriculturally active areas of Slovakia. This decrease in agricultural land use was at the expense of an increase in urban areas and in the processes of greening, forestation and water body construction.

Soil organic matter (Som) takes part in many environmental functions and, depending on the conditions, it can be a source or a sink of the greenhouse gases. Presently, the changes in soil organic carbon (SoC) stock can arise because of the climatic changes or changes in the land use and land management. A promising method in the estimation of SoC changes is modelling, one of the most used models for the prediction of changes in soil organic carbon stock on agricultural land being the rothC model. Because of its simplicity and availability of the input data, rothC was used for testing the efficiency to predict the development of SoC stock during 35-year period on agricultural land of Slovakia. The received data show an increase of SoC stock during the first (20 years) phase and no significant changes in the course of the second part of modelling. The increase of SoC stock in the first phase can be explained by a high carbon input of plant residues and manure and a lower temperature in comparison with the second modelling part.

Tobiašová E., Barančíková G., Gömöryová E., Makovníková J., Skalský R., Halas J., Koco Š., Tarasovičová Z., Takáč J., Špaňo M. Soil organic matter (SOM) plays an important role in the soil aggregation and vice versa, its incorporation into the soil aggregates is one of the mechanisms of soil organic carbon stabilization. In this study the influence of labile carbon fractions on the fractions of dry-sieved (DSA) and wet-sieved (WSA) macro-aggregates and the relationship between the content of total organic carbon (TOC) and its labile fractions in the soil and in the fractions of macro-aggregates were determined. The experiment included six soil types (Eutric Fluvisol, Mollic Fluvisol, Haplic Chernozem, Haplic Luvisol, Eutric Cambisol, Rendzic Leptosol) in four ecosystems (forest, meadow, urban, and agro-ecosystem). In the case of DSA, the contents of labile fractions of carbon, in particular cold water extractable organic carbon (CWEOC) and hot water extractable organic carbon (HWEOC), had a higher impact on the proportions of larger fractions of macro-aggregates (3-7 mm), while in the case of WSA, the impact of labile fractions of carbon, mainly labile carbon (C L ) oxidizable with KMnO 4 , was higher on the proportions of smaller fractions of aggregates (0.25-1 mm). The WSA size fraction of 0.5-1 mm seems an important indicator of changes in the ecosystems and its amounts were in a negative correlation with C L (r = -0.317; P < 0.05) and HWEOC (r = -0.356; P < 0.05). In the WSA and DSA size fractions 0.5-1 mm, the highest variability in the contents of TOC and C L was recorded in the forest ecosystem > meadow ecosystem > urban ecosystem > agro-ecosystem. The higher were the inputs of organic substances into the soil, the greater was the variability in their incorporation into the soil aggregates. The influence of the content of TOC and its labile forms on their contents in the DSA and WSA was different, and the contents of TOC and C L in the aggregates were more significantly affected by the C L content than by water soluble carbon. In the case of WSA fractions, their carbon content was more affected in the 1-2 mm than in 0.5-1 mm fraction.

AbstractSoil organic carbon (SOC) in agricultural land forms part of the global terrestrial carbon cycle and it affects atmospheric carbon dioxide balance. SOC is sensitive to local agricultural management practices that sum up into regional SOC storage dynamics. Understanding regional carbon emission and sequestration trends is, therefore, important in formulating and implementing climate change adaptation and mitigation policies. In this study, the estimation of SOC stock and regional storage dynamics in the Ondavská Vrchovina region (North-Eastern Slovakia) cropland and grassland topsoil between 1970 and 2013 was performed with the RothC model and gridded spatial data on weather, initial SOC stock and historical land cover and land use changes. Initial SOC stock in the 0.3-m topsoil layer was estimated at 38.4 t ha−1 in 1970. The 2013 simulated value was 49.2 t ha−1, and the 1993–2013 simulated SOC stock values were within the measured data range. The total SOC storage in the study area, cropland and grassland areas, was 4.21 Mt in 1970 and 5.16 Mt in 2013, and this 0.95 Mt net SOC gain was attributed to inter-conversions of cropland and grassland areas between 1970 and 2013, which caused different organic carbon inputs to the soil during the simulation period with a strong effect on SOC stock temporal dynamics.