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Simulating Irrigation Requirements for Vegetable Crops in a Humid Region Considering a Changing Climate  Open Access

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  Journal of Natural Resources and Agricultural Ecosystems. 3(1): 1-16. (doi: 10.13031/jnrae.16048) @2025
Authors:   Meaghan Kilmartin, Chandra A. Madramootoo
Keywords:   Climate change, Crop modeling, Humid regions, Irrigation water requirement.

Highlights

  • Water deficiency of 50% did not reduce yields.
  • Potato needs a minimum of 247 mm of water by the 2080s.
  • Irrigation requirements of squash are 124 mm for 2080s.

Abstract. This study assessed the supplemental irrigation needs in a humid vegetable producing region of Quebec using the AquaCrop model. Three irrigation treatments were investigated, comprising a maximum allowable depletion (MAD) of 20%, 35%, and 50% of plant-available water (AW) for potato and squash cultivated on sandy soils. The AquaCrop models were calibrated to field measurements of soil moisture in 2022. Potato and squash models simulated soil moisture with a strong agreement to field sensor measurements, with a Willmott index of agreement of 0.91 and 0.84, respectively. Statistical analysis revealed that both the historical weather and the irrigation treatment (20%, 35%, or 50% depletion of AW) had a significant effect on net irrigation requirement. The MAD of 50% AW demonstrated significant water-saving potential, particularly in dry years where crop-water demand was significantly higher. Under the 50% MAD, the mean net irrigation requirement for potato and squash in historical dry years were 265 mm and 151 mm, respectively. The models were then used to predict the impact of climate change on irrigation requirements for the periods 2050 and 2080. The irrigation requirement for potato is predicted to significantly increase by the 2080s compared to the historical period (1997–2021), under the CMIP-6 SSP5-8.5 high emissions scenario. Projected irrigation requirements for squash remained stable. Irrigation treatment significantly impacted the net irrigation requirement, with an MAD set at 50% AW significantly reducing irrigation requirements across all climate periods.

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