Water use efficiency in agricultural areas of Slovakia in the period 1961–2020 and according to climate change scenarios

An assessment of the trend in water use efficiency (WUE) in agricultural regions of Slovakia was carried out for the period 1961–2020 and climate change scenarios. For the assessment, simulations with agroecological model DAISY were applied. Simulations were carried out for representative soil profiles of selected regions. Crop rotations including grain maize, spring barley, winter wheat, sugar beet and potatoes were taken for modelling. According to the results the average WUE of crops decreased by approximately 1 kg/mm in the period 1991–2020 compared to the period 1961–1990. The largest decrease in WUE was found in the northeast of the Danube Lowland in the Nitra area, in the case of potatoes on the upper Žitný ostrov (Bratislava area). Simulations have confirmed that soil properties and nutrient reserves in the soil play an important role in WUE in addition to climatic conditions. With lower fertilization doses, WUE achieves lower values. Simulations according to emission scenarios for the Rišňovce and Milhostov sites showed an increase in WUE at higher CO2 concentrations (RCP 8.5) for spring barley at both sites and for winter wheat at the Rišňovce site. In the case of maize, there was a slight increase in both locations under the RCP 2.6 emission scenario, and in the RCP 4.5 and 8.5 scenarios, there was a decrease in the WUE of maize. Statistical analysis of the results according to the scenarios revealed a higher variability of WUE values for all crops compared to the period 1961–1990.