Deficit irrigation management of sugar beet using canopy temperature based crop water stress index

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

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 5/1/2023
Publication Date: 6/28/2023
Citation: King, B.A., Tarkalson, D.D., Bjorneberg, D.L. 2023. Deficit irrigation management of sugar beet using canopy temperature based crop water stress index. Meeting Abstract. 2300228:1-28. https://doi.org/10.13031/aim.202300228.
DOI: https://doi.org/10.13031/aim.202300228

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 800 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 requires precise irrigation scheduling considering available soil water 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 using automated CWSI based irrigation scheduling of sugar beet on seasonal irrigation requirement, crop evapotranspiration (ET), seasonal soil water depletion, root yield, sugar yield and water use efficiency compared to full irrigation. There were no significant differences in root and sugar yield between full irrigation and 0.2 CWSI DI treatments 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 sugar 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 irrigation scheduling to reduce seasonal irrigation requirements with no significant effect on root and estimated recoverable sugar 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 800 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 requires precise irrigation scheduling considering available soil water 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 (ET), seasonal soil water depletion, root yield, sugar yield and water use efficiency compared to full irrigation. There were no significant differences in root and sugar yield between full irrigation and 0.2 CWSI DI treatments 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 sugar water production functions were curvilinear concave downward. Root and sugar 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 irrigation scheduling to reduce seasonal irrigation requirements with no significant effect on root and estimated recoverable sugar yield.