Quantifying irrigation uptake in olive trees: a proof-of-concept approach combining isotope tracing and Hydrus-1D

ABSTRACT

An isotope-enabled module of Hydrus-1D was applied to a potted olive tree to trace water parcels originating from 26 irrigation events in a glasshouse experiment. The soil hydraulic parameters were optimized via inverse modelling by minimizing the discrepancies between observed and simulated soil water content and soil water isotope (¹⁸O) values at three soil depths. The model’s performance was validated with observed sap flow z-scores and xylem water ¹⁸O. We quantified the source and transit time of irrigation water by analysing the mass breakthrough curves derived from a virtual tracer injection experiment. On average, 26% of irrigation water was removed by plant transpiration with a mean transit time of 94 hours. Our proof of concept work suggests that transit time may represent a functional indicator for the uptake of irrigation water in agricultural ecosystems.

KEYWORDS:

• transit time
• soil water content
• sap flow
• root water uptake
• virtual tracer injection experiment
• isotope labelling experiment

Editor A. Fiori; Associate Editor (not assigned)

Editor A. Fiori; Associate Editor (not assigned)

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/02626667.2023.2218552

Additional information

Funding

This study was supported by the MiUR-PRIN Project “WATer mixing in the critical ZONe: observations and predictions under environmental changes – WATZON” [grant 2017SL7ABC]. The work described in this paper and related research have been conducted with the support of the Italian inter-University PhD course in Sustainable Development and Climate Change.