DFG Research Unit: Land-Atmosphere Feedback Initiative (LAFI): Using real-time isotopic in-situ measurements to partition evapotranspiration into soil evaporation and plant transpiration at two distinct cropland sites

Agricultural crops play a crucial role in the global water cycle. Yet, climate change may alter crop physiology, agricultural ecosystems, and interactions within the land-atmosphere (L-A) system. Understanding crop transpiration (T) and soil evaporation (E) rates, along with their temporal dynamics and connection to the L-A system, is essential for predicting future hydro-climatic conditions and assessing agricultural land-use practices, particularly under the increasing frequency of extreme weather events.
Here, we introduce the DFG Research Unit “LAFI” (Land-Atmosphere Feedback Initiative) subproject 3, which focuses on partitioning evapotranspiration into E and T using real-time water isotope in-situ measurements.
We will study water fluxes and their isotopic composition across the L-A system to investigate water-related processes in high temporal and spatial resolution via canopy and leaf chambers for evapotranspiration (ET) and T, as well as membrane probes for soil water vapor isotope measurements. This innovative isotope measurement platform will enable the determination of root water uptake (RWU) contributions and depths for key crop species (wheat and maize) at the Land-Atmosphere Feedback Observatory (University of Hohenheim, Germany). Additionally, it will facilitate the evaluation of water transit times and the partitioning of ET.
Analyses will be species-specific and will examine the impact of varying environmental conditions on RWU, water transit times, ET, and ET partitioning. The results will provide insights into the vulnerability of crop species to climate-induced changes in precipitation patterns and soil moisture availability.