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Practical irrigation scheduling at the sub-field scale: Comparing OpenET and capacitance soil moisture sensors against a TSEB reference in dry edible beans
Journal article   Open access   Peer reviewed

Practical irrigation scheduling at the sub-field scale: Comparing OpenET and capacitance soil moisture sensors against a TSEB reference in dry edible beans

Shuhua Xie, Angie Gradiz, Xin Qiao, Joseph Oboamah, Wei-zhen Liang, Jun Wang and PoNien Su
Agricultural water management, Vol.335, 110734
10/01/2026
DOI: 10.1016/j.agwat.2026.110734
url
https://doi.org/10.1016/j.agwat.2026.110734View
Published (Version of record) Open Access

Abstract

Accurate estimation of daily crop evapotranspiration (ET) at the sub-field level is critical for precision irrigation scheduling and management, yet few studies have examined how satellite-based ET products represent soil-driven spatial variability within a single field. We compared three ET estimation approaches across three management zones delineated by apparent electrical conductivity in a commercial dry edible bean field in western Nebraska, U.S.A., during a 47-day period (July 28–September 12, 2023) spanning reproductive development through physiological maturity. The approaches were Two-Source Energy Balance (TSEB) driven by ground-installed infrared radiometer thermometers (IRT), used as the comparison reference; an operational soil water balance (SWB) based on commercial capacitance sensors with factory-default calibration; and satellite-based ET from OpenET. The three zones showed contrasting sensor-derived root-zone water status, while vegetation indices and yield differed significantly (p < 0.05), confirming distinct growing environments under a common producer-selected irrigation prescription. The ET from OpenET ensemble showed moderate daily agreement with TSEB (R² = 0.33–0.52, RMSE = 1.0–1.2 mm/day), whereas SWB showed poor agreement (R² = 0.01–0.05, RMSE = 3.1–7.0 mm/day), produced physically implausible residuals, and was sensitive to the sensor upper threshold in two zones. Among six individual OpenET models, eeMETRIC achieved the highest correlations (R² = 0.38–0.60), while SIMS and SSEBop combined relatively high correlations (R2 = 0.35–0.58) with the largest monotonic descriptive gradients across zone-associated extraction areas. The findings highlight limitations of the factory-default capacitance-sensor workflow and the potential of select OpenET models for sub-field applications, while emphasizing the need for validation over larger contiguous management zones. OpenET's accessibility makes it a promising complement to ground-based monitoring where management zones span multiple pixels that are predominantly contained within zone boundaries. These findings are limited to the monitored reproductive-to-maturity period and do not establish full-season ET or season-long irrigation-scheduling performance. •Daily ET from OpenET, capacitance sensors, and TSEB compared in dry edible beans.•OpenET ensemble agreed moderately with TSEB (R² = 0.33–0.52, RMSE 1.0–1.2 mm/day).•Factory-default sensor water balance gave implausible, threshold-sensitive daily ET.•eeMETRIC, SIMS, and SSEBop tracked zone-to-zone ET patterns most closely.•OpenET can complement ground sensors where zones span multiple 30 m pixels.
 Capacitance soil moisture sensor Dry edible beans Management zones OpenET TSEB

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