Integrated Monitoring Framework for Site-Specific Irrigation Management in California Almond Orchards

California almond production faces increasing pressure to improve irrigation efficiency under limited and variable water supplies. Variable-rate micro-irrigation offers a promising pathway to address spatial variability in orchard water demand; however, its effective implementation requires reliable, field-scale information on soil water availability, tree water status, irrigation inputs, and crop productivity response. This study developed and applied an integrated monitoring framework to support site-specific irrigation management in a commercial almond orchard over three growing seasons (2019–2021). Fourteen monitoring locations were established across contrasting soil and irrigation management zones. At each location, applied irrigation water was measured, soil water dynamics were monitored using neutron probes, and midday stem water potential was measured on three representative trees with a pressure chamber at weekly to biweekly intervals. Crop water use was evaluated using evapotranspiration estimates supported by in-field observations, including eddy covariance measurements, to provide context for irrigation scheduling decisions. Yield data were collected at all monitoring locations to quantify spatial and temporal variability in production and to evaluate crop responses to irrigation management informed by the integrated dataset.

Across the study period, average almond yield increased from approximately 1.93 t ha⁻¹ in 2019 to 2.58 t ha⁻¹ in 2021, while substantial spatial variability in both yield and water use persisted among monitoring locations. These findings reinforce the need for variable-rate irrigation approaches in heterogeneous orchard environments. The results demonstrate the value of combining soil, plant, irrigation, and atmospheric measurements within a coordinated monitoring framework capable of informing variable-rate micro-irrigation management. This work provides a foundation for the development of data-driven, site-specific irrigation strategies that move beyond uniform management and enhance water productivity in almond orchards under increasing water constraints.