Climate change induced drought inhibits plant growth in agricultural systems – A lysimeter study

Climate models predict an increase in the average temperature, an increase in heat and drought periods in summer and heavier rainfall events for Austria (APCC, 2014; IPCC, 2021). Eventually, advancing droughts can lead to substantial yield losses, which will be more pronounced on soils with low water storage capacity (Eitzinger et al., 2013). Especially in dry regions like the Marchfeld (east of Vienna), Austria’s most productive region for grain and vegetables, this may have severe consequences for food security.

In our study, we investigated the combined effects of different soil types and altered precipitation on the soil-plant-nexus in a lysimeter facility from 2017-2019. This facility consists of 18 gravitation lysimeters representing the three main soil types of the Marchfeld, namely calcaric Phaeozem (Ps), calcic Chernozem (Ch) and gleyic Phaeozem (Pg). Half of the lysimeters were irrigated according to current precipitation patterns and half according to the precipitation pattern predicted for the period 2071-2100 in the Marchfeld region, simulating drought periods and heavy rain events. Spring wheat, spring barley and winter wheat were cultivated in all lysimeters in 2017, 2018 and 2019, respectively. Mustard was cultivated as a cover crop after spring wheat and incorporated as mulch. The following spring barley had substantially higher yields than spring wheat. This might be due to the improved water infiltration and organic matter input provided by the cover crop (Kirchman, 2011) and/or the larger crop damage by animals in 2017. 

Drought events resulted in an average decline of grain yield by 66% (p<0.05) in spring wheat, 40% (p=0.13) in spring barley and 39% (p<0.05) in winter wheat. In all soil types, the yield of winter wheat was higher than of the other crops, which could indicate its ability to make better use of water resources than the spring crops. This underlines the importance of optimizing sowing dates as an adaptation strategy to climate change. The increase of the δ¹³C value, an indicator for the stomata conductance, in the “predicted” scenario confirmed that drought stress was limiting plant growth.  δ¹³C values were also higher in the Phaeozem than in the Chernozem, with the first having a lower soil water holding capacity.

In contrast to biomass, nitrogen content of grain did not change between current and predicted precipitation patterns, indicating no impairment of grain quality. Furthermore, the nitrogen use efficiency tended to be higher in the current scenario than in the predicted scenario and was highest for winter wheat. Overall, plant biomass, plant nitrogen content and plant δ¹⁵N values were differently affected by soil type, however as there were no significant interaction effects with precipitation, plants responded identically to the precipitation pattern on all soil types, i.e. significant decline in crop production under drought stress.

Our results exemplify the pressing need to develop and implement adaptation strategies in agriculture, taking into consideration local pedoclimatic characteristics. Introducing more resilient crop species, diversifying the crop rotation and increasing the system’s water use efficiency are promising measures that should be investigated further.