Bonet et al. (2026) A user-friendly decision support tool for irrigation scheduling in smallholder olive orchards

Identification

• Journal: Agricultural Water Management
• Year: 2026
• Authors: L. Bonet, Felix Thomas, M.A. Martínez-Gimeno, M. Tasa, E. Badal, J.G. Pérez-Pérez, Ulrike Werban
• DOI: 10.1016/j.agwat.2026.110131

Research Groups

• Irrigation Advisory Service, Valencian Institute for Agricultural Research (STR-IVIA), Moncada, Valencia, Spain.
• Helmholtz Centre for Environmental Research GmbH – UFZ, Leipzig, Germany.
• Centre for the Development of the Sustainable Agriculture, Valencian Institute for Agricultural Research (CDAS-IVIA), Moncada, Valencia, Spain.

Short Summary

This study developed and validated a user-friendly decision support tool (DST) based on the Soil-Atmosphere Adjusted Model (SAAM) to optimize irrigation in smallholder olive orchards. The tool successfully reduced irrigation water use by 11% while maintaining crop yields and physiological health through automated sensor-based feedback.

Objective

• To develop a simplified, sensor-based water-balance model (SAAM) and a modular digital infrastructure to provide automated weekly irrigation recommendations for small-scale Mediterranean olive growers.

Study Configuration

• Spatial Scale: A commercial olive orchard (cv. ‘Serrana’) located in Viver, Castellón, Spain (39º55’46” N, 0º36’47” W), characterized by loam soil and a semi-arid Mediterranean climate.
• Temporal Scale: Two consecutive growing seasons (2022 for calibration and 2023 for validation).

Methodology and Data

• Models used: Soil-Atmosphere Adjusted Model (SAAM), which adjusts irrigation based on environmental factors ($k{ET0}$) and soil water status ($k{\theta}$); FAO-56 Penman-Monteith for reference evapotranspiration ($ET_0$).
• Data sources:
  • Sensors: TEROS 10 capacitive soil moisture sensors and ZL6 data loggers.
  • Meteorological: Historical 20-year $ET_0$ data from the Spanish SiAR network and real-time data from an on-site Davis Vantage Pro2 weather station.
  • Software: Python-based data processing, Docker containers for platform independence, and the System for automated Quality Control (SaQC).

Main Results

• Physiological Thresholds: Identified optimal Relative Water Status (RWS) boundaries for olive trees: a lower limit ($RWS{LL}$) of 0.63 and an upper limit ($RWS{UL}$) of 0.73.
• Water Efficiency: The SAAM-based DST reduced total seasonal irrigation by 11% (99.4 mm) compared to a technician-guided control strategy (111.3 mm).
• Crop Performance: No significant differences were found in olive yield (23.0 vs. 22.2 kg $tree^{-1}$) or oil yield (2.41 vs. 2.33 kg $tree^{-1}$) between the SAAM and control treatments.
• Physiological Status: Maintained midday stem water potential ($\Psi{stem}$) and stomatal conductance ($gs$) within non-limiting ranges (seasonal average $\Psi_{stem}$ of -1.29 MPa).
• Productivity: Improved irrigation water productivity for olives (5.52 kg $m^{-3}$ for SAAM vs. 4.76 kg $m^{-3}$ for control).

Contributions

• Smallholder Accessibility: Developed a parsimonious model that requires only two data streams (soil moisture and $ET0$), eliminating the need for complex crop coefficients ($Kc$) or expert-level calibration.
• Automated Infrastructure: Created a robust, scalable data pipeline that integrates real-time sensor acquisition, automated quality control, and cloud-based processing for mobile delivery.
• Empirical Validation: Provided field-calibrated RWS thresholds specifically linked to olive tree physiological stress markers ($\Psi{stem}$ and $gs$) in Mediterranean environments.

Funding

• European PRIMA project “HANDYWATER”.
• Spanish Ministry of Science and Innovation (MCIN/AEI/10.13039/5011000110033) and European Union NextGenerationEU/PRTR (Project PCI2021–121940).
• German Federal Ministry for Education and Research (BMBF) (Grant 01DH21013A).
• Generalitat Valenciana pre-doctoral contract (ACIF-2021/413).

Citation

@article{Bonet2026userfriendly,
  author = {Bonet, L. and Thomas, Felix and Martínez-Gimeno, M.A. and Tasa, M. and Badal, E. and Pérez-Pérez, J.G. and Werban, Ulrike},
  title = {A user-friendly decision support tool for irrigation scheduling in smallholder olive orchards},
  journal = {Agricultural Water Management},
  year = {2026},
  doi = {10.1016/j.agwat.2026.110131},
  url = {https://doi.org/10.1016/j.agwat.2026.110131}
}

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