Abstract
In this study, differences in soil structure in different ecosystems (forest, meadow, urban, and agro-ecosystem) and soil types (Haplic Chernozem, Haplic Luvisol, Haplic Stagnosol) with a dependence on the influence of quantity and quality of soil organic matter and the particle size distribution on fraction composition of soil aggregates were compared. Soils had different productive capacity and particle size distribution. The most favourable soil structure was in the agro-ecosystem, then in forest, meadow, and urban ecosystem. The worst soil structure was in Haplic Stagnosol. An important indicator in assessing of ecosystem influence, water-resistant macro-aggregates of the 0.5-1 mm size fraction seems to be. This fraction was the only one which was statistically significantly influenced by the ecosystem, and also the only one which was not statistically significantly influenced by the soil type. This fraction also was not influenced either with the quantity and quality of soil organic matter, or with the particle size distribution. The quantity of soil organic matter is reflected in relation to the fractional composition of dry-sieved aggregates and its quality in relation to waterresistant aggregates. Large fractions of water-resistant macro-aggregates were in positive correlation with C : N ratio, the amount of extracted humus substances, or stability and quality of humic acids; while smaller fractions were in negative correlation just with these parameters. Clay and silt fractions had a positive influence on waterresistant macro-aggregates formation, while sand fraction had negative and vice versa.