Evaluation of canopy temperature based crop water stress index for deficit irrigation management of sugar beet in semi-arid climate

Authors: King, Bradley - Brad; Tarkalson, David; Bjorneberg, David - Dave

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/30/2023
Publication Date: 2/20/2024
Citation: King, B.A., Tarkalson, D.D., Bjorneberg, D.L. 2024. Evaluation of canopy temperature based crop water stress index for deficit irrigation management of sugar beet in semi-arid climate. Applied Engineering in Agriculture. 40(1):95-110. https://doi.org/10.13031/aea.15822.
DOI: https://doi.org/10.13031/aea.15822

Interpretive Summary: Sugar beet is an economically important crop in the semi-arid Intermountain Western U.S. with seasonal water use ranging from 500 to 900 mm. Sugar beet is a deep-rooted crop in unrestricted soil profiles that can readily utilize stored soil water to reduce seasonal irrigation requirements. Deficit irrigation (DI) management of sugar beet using thermal-based crop water stress index (CWSI) has the potential to facilitate utilization of stored soil water to reduce seasonal irrigation requirements. The objective of the research was to implement and evaluate the effect of automated DI scheduling of sugar beet, using three daily average CWSI thresholds (0.2, 0.35 and 0.55) on seasonal irrigation requirement, crop evapotranspiration, seasonal soil water depletion, root yield, estimated recoverable sugar (ERS) yield and water use efficiency compared to full irrigation. There were significant differences in crop evapotranspiration, seasonal soil water depletion, root yield, estimated recoverable sugar (ERS) yield between irrigation treatments. However, there were no significant differences in root and ERS yield between full irrigation and 0.2 CWSI DI treatment while seasonal ET was significantly decreased, seasonal soil water extraction was significantly increased, and seasonal irrigation amounts were reduced 133 to 185 mm. The results indicate that irrigating when average daily CWSI sugar beet exceeds 0.2 is an effective means for mild deficit irrigation scheduling to reduce seasonal irrigation requirements with no significant effect on root and ERS yield.

Technical Abstract: Sugar beet is an economically important crop in the semi-arid Intermountain Western U.S with seasonal water use ranging from 500 to 900 mm. Sugar beet is a deep-rooted crop in unrestricted soil profiles that can readily utilize stored soil water to reduce seasonal irrigation requirements. Effective use of stored soil water below 0.6 m requires precise irrigation scheduling and knowledge of soil water availability below 0.6 m, which is usually unavailable due to the labor and expense of soil water monitoring at deeper depths and uncertainty in effective rooting depth and soil water holding capacity. Deficit irrigation (DI) management of sugar beet using thermal-based crop water stress index (CWSI) has the potential to overcome soil water monitoring limitations and facilitate utilization of stored soil water to reduce seasonal irrigation requirements. The objective of the research summarized in this paper was to implement and evaluate the effect of automated DI scheduling of sugar beet, using three daily average CWSI thresholds (0.2, 0.35 and 0.55) on seasonal irrigation requirement, crop evapotranspiration, seasonal soil water depletion, root yield, estimated recoverable sugar (ERS) yield and water use efficiency compared to full irrigation. There were no significant differences in root and ERS yield between full irrigation and 0.2 CWSI DI treatment while seasonal ET was significantly decreased, seasonal soil water extraction was significantly increased, and seasonal irrigation depths were reduced 133 to 185 mm. Root and ERS yield water production functions were curvilinear with a downward concave. Root and ERS yield water use efficiencies were constant or increased slightly for crop evapotranspiration reductions up 85% of full irrigation evapotranspiration. The results indicate that irrigating when average daily CWSI sugar beet exceeds 0.2 is an effective means for mild deficit irrigation scheduling to reduce seasonal irrigation requirements with no significant effect on root and ERS yield.