Land cover influences microclimate and non-rainfall water inputs in temperate agricultural environment

Authors: GROH, JANNIS - University Of Bonn; PUTZ, THOMAS - Forschungszentrum Juelich Gmbh; BEYSENS, DANIEL - Sorbonne Universities, Paris; CUXART, JOAN - Universitat De Les Illes Balears; AGAM, NURIT - Ben Gurion University Of Negev; KUPPER, WERNER - Forschungszentrum Juelich Gmbh; Colaizzi, Paul; VEREECKEN, HARRY - Forschungszentrum Juelich Gmbh; GERKE, HORST - Zalf-Institute Of Soil Landscape Research; AMELUNG, WULF - University Of Bonn

Submitted to: Journal of Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/2026
Publication Date: 2/4/2026
Citation: Groh, J., Putz, T., Beysens, D., Cuxart, J., Agam, N., Kupper, W., Colaizzi, P.D., Vereecken, H., Gerke, H.H., Amelung, W. 2026. Land cover influences microclimate and non-rainfall water inputs in temperate agricultural environment. Journal of Hydrology. 669:Part A. Article no. 135040. https://doi.org/10.1016/j.jhydrol.2026.135040.
DOI: https://doi.org/10.1016/j.jhydrol.2026.135040

Interpretive Summary: The water cycle on land is important for weather forecasting, crop production, domestic and industrial water supply, infrastructure, and economic growth, among many other factors. In many climates, non-rainfall water can be a significant but often overlooked component of the water cycle. Non-rainfall water can include dew, fog, frost, rime, and soil water vapor. Methods to accurately quantify non-rainfall water are presently lacking, as are methods to identify the different types of non-rainfall water. Scientists in Germany, France, Spain, Israel, and ARS in Bushland, Texas developed new methods to quantify and distinguish the various types of non-rainfall water. The methods included novel uses of sensors to identify fog and dew, and tests showed that accuracy was improved for quantifying non-rainfall water events. Tests also showed that dew and sometimes fog were the largest contributors to non-rainfall water. The type of land cover, such as farmed or grassland, influenced the amount of dew that formed. The new methods will improve the overall accuracy of quantifying the water cycle, which will enable more efficient use of water resources.

Technical Abstract: Non-rainfall water inputs (NRWI) from dew, fog, frost, rime and soil water vapour adsorption (WVA) are key components of the terrestrial water cycle, but their individual contribution to the water budget is unclear due to a lack of suitable methods for identification and quantification. Here, we present a refined method to quantify and partition NRWI using weighing lysimeters. The method's novelty lies in the variables used to determine when dew and frost (leaf-wetness), fog and rime (air visibility) occur. We applied this methodology to grassland and arable land lysimeters and compared it to the established method that relies on relative humidity and estimated dew-point temperature to quantify and partition NRWI. Our results showed large differences between the refined and established method. The established method predicted larger amounts of dew (55 %) and WVA (2522 %), but no fog. NRWI mostly came from dew. Dew rates per event were generally higher on arable land, but the total amount of dew was larger on grassland due to higher frequency of dew formation. Dew amount differences could be attributed to land cover type, which promoted dew formation in the grassland while the arable ecosystem largely lost water through evapotranspiration (e.g. stomatal conductance, canopy-structure). We conclude that land cover type is a key control for microclimate (surface temperature, relative humidity), which significantly affects dew formation, while effects on fog or WVA are weaker. These effects are better determined by lysimeter assessment with a visibility and leaf-wetness device than by other existing NRWI identification systems.