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ARS Home » Pacific West Area » Riverside, California » Agricultural Water Efficiency and Salinity Research Unit » Research » Publications at this Location » Publication #416178
Research Project: Water Management for Crop Production in Arid and Semi-Arid Regions and the Safe Use of Alternative Water Resources

Location: Agricultural Water Efficiency and Salinity Research Unit

Title: Climate change impacts on almond and pistachio crops in the Mediterranean region of the United States

Author
item KANDHWAY, ANSHIKA - University Of California
item SCARPARE, FABIO - Washington State University
item LIU, MINGLIANG - Washington State University
item NELSON, ROGER - Washington State University
item ADAM, NELSON - Washington State University
item Anderson, Raymond - Ray
item CONKLIN, MARTHA - University Of California
item SAFEEQ, MOHAMMAD - University Of California

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2024
Publication Date: 12/6/2024
Citation: Kandhway, A., Scarpare, F., Liu, M., Nelson, R., Adam, N.C., Anderson, R.G., Conklin, M.H., Safeeq, M. 2024. Climate change impacts on almond and pistachio crops in the Mediterranean region of the United States. Agricultural Water Management. 307, 109219. https://doi.org/10.1016/j.agwat.2024.109219.
DOI: https://doi.org/10.1016/j.agwat.2024.109219

Interpretive Summary: Almonds and pistachios are major tree crops in the San Joaquin Valley of California. These crops have high irrigation needs that cannot be easily reduced in drought years where irrigation water supplies become constrained. There is concern that crop water needs in the San Joaquin Valley will increase under future climate change while irrigation supplies will become less reliable and more variable. Understanding how almond and pistachio water demands will change under future climate change will be critical for sustainable agricultural management, particularly as groundwater pumping restrictions from the Sustainable Groundwater Management Act come into force. In this study, we modeled the impact of different climate change aspects, including warming only and carbon dioxide increases, on almond and pistachio water use. We found modest changes (<10%) for almond and pistachio water use under common climate change scenarios, with carbon dioxide fertilization effects offsetting increased meteorological demand due to higher temperatures. We also found a longer (two-four week) non-dormant period for both crops, which suggests a longer irrigation season and more labor in the spring and fall for irrigation management. These results are of import for farmers and irrigation managers who need to understand how almond and pistachio water demands may change in the future.

Technical Abstract: Almonds and pistachios tree crops are socio-economically significant crops grown in California's San Joaquin Valley (SJV). Continuing commercial production with efficient irrigation planning under changing climate requires an extensive understanding of their biophysical interactions such as altered phenology, biomass accumulation, transpiration, and other processes. This study aims to investigate the impact of climate change (warming-only) and elevated atmospheric CO2 (eCO2) levels on phenology and water use (ETc) responses by almonds and pistachios using VIC-CropSyst, a coupled process-based crop-hydrology model. The model was calibrated and validated using observations on crop evapotranspiration. The simulated crop responses to warming-only and eCO2 revealed compounding effects on chill accumulation, phenology, biomass accumulation, and eventually on crop water use. The active growth period from bud break to dormancy was prolonged by 10-25 days for both crops under simulated RCP4.5 and RCP8.5 scenarios compared to the baseline. The annual ETc under warming-only scenarios showed a slight increase for almonds (by 1% under RCP4.5 and 3% under RCP8.5) and a higher increase for pistachios (by 8% under both RCP4.5 and RCP8.5) by the mid-21st century. These increases in ETc translate to 260 (almonds) and 180 (pistachios) million m3/year of additional water for irrigation in the absence of eCO2 effects. The eCO2 is expected to moderately reduce irrigation demand by 35 million m3/year for almonds and increase by 140 million m3/year for pistachios over the baseline. The outcomes can guide decision-makers to anticipate potential threats and concoct adaptive strategies by managing irrigation and choosing suitable cultivars or alternate crops.