The impact of drip irrigation on structural stability of soil aggregates was studied in soils of an apple (Malus domestica Borkh.) orchard, developed on marl. The field study was carried out in a slopping (20%) terrain in north-eastern Slovenia at three slope positions (upslope, midslope and downslope), involved comparison of irrigated versus non-irrigated situations after 6 years of drip irrigation practice. Structural stability was studied in three soil layers (0–5, 5–15 and 15–30 cm) at the end of irrigation season (in September). In the same samples, soil organic matter content, total carbonates and soil moisture contents were determined. Especially in the surface layer (0-5 cm), drip irrigation significantly reduced structural stability and soil organic matter content. In fine textured calcareous soils, total soil carbonates were found to be the prevalent contributors to the improvement of structural stability, compared to soil organic matter. Structural stability was strongly positive correlated with total carbonates and negatively correlated with soil organic matter. Thus, a negative effect of irrigation on organic matter had less destructive consequences on structural stability as expected. After all, for the sustainability of irrigation practice, soil organic matter content should be regulated.
European silver fir-beech forests are characteristic for the Dinaric mountains and represent one of the most important forest ecosystem in the region. Very little is known about the long-term effects of forest management and intensity of logging on soil organic matter quality and carbon stocks in the forest soil. As quality of forest soils is associated with the range of stand disturbance due to the intensity of logging, its properties are often used as a criterion in valorisation of sustainability of forest management systems. Therefore, from the aspect of different intensity of logging we studied changes in soil propertis as well as changes in C and N stocks in the forest soils. Preliminary results from Slovenian sites show that the intensity of logging causes a decrease in the total soil organic carbon and nitrogen contents, wider C/N ratio and increases of pH values, with the largest level of alternations in the organic part of the soils.