Changing drought occurrence and severity affecting agriculture and forestry in Slovakia

Drought is a natural phenomenon that occurred in Central Europe in the past, but it is becoming a more serious problem due to the changes in its occurrence and intensity related to climate change. We analysed changes in air temperature and precipitation amounts in Slovakia from 1931 to 2020 as well as changes in drought occurrence and intensity using the Standardised Precipitation and Evapotranspiration Index (SPEI) since 1961. Further, cluster analysis was used to determine regions with similar drought occurrences. For each of the identified five clusters, drought characteristics were determined and compared between two reference periods 1961–1990 and 1991–2020.

While a decrease in the number of months with SPEI-1 below − 1 was identified in autumn, spring and summer months showed a drying tendency. Overall, we can say that we observed a shift in drought occurrence from autumn and winter months to spring and summer months. The clearest tendency in drought events was observed in the western part of Slovakia covering areas with agriculturally intensive land use. Besides prolonging drought events, there was also a higher accumulated deficit for each event. Considering SPEI-12, the severely to extremely dry conditions repeatedly occurred in clusters 1 and 5 since 2011, affecting agriculturally intensively used areas and causing yield losses. These regions also experience the most severe change in water balance concerning the relative SPEI-12. Generally, approximately two-thirds of Slovakia experience a decreasing value of rSPEI-12.

Observed drying tendency in spring months is a great problem for the agriculture, because of the seeding and germination of some spring crops such as maize, sunflower or soya. This is also the main cause, why the farmers seed winter crops rather than spring crops. This is a reason, why the cultivation area of spring barley has had a decreasing tendency in south-western part of Slovakia since 2018 (Križanová 2022). The reports published in the last years by the Regional Agricultural and Food Chamber Galanta (south-western part of Slovakia) show that the farmers try to use autumn soil moisture for securing better crop yields next year. Therefore, they prefer rather winter cultivars of crops than their spring cultivars. They even sow spring barley in autumn months. It is a way, how to ensure higher yields and better use of agroclimatic conditions while maintaining malting parameters (Križanová 2022; Križanová 2023).

The same situation is in the forestry. According to internal information provided by the Forests of the Slovak Republic, state enterprise, the foresters start to plan the seeding of tree seedlings rather for autumn months, because the success of spring planting is lower due to the drying of seedlings as the result of lower soil moisture in spring.