Journal of Taiwan Agricultural Research

Author:Shin-Ruei Lee*、Ping-Wei Sun、Hung-Yu Dai*

Abstract:

Efficient irrigation management is essential for optimizing water use and maintaining crop productivity, particularly in regions such as Taiwan where rainfall distribution is uneven in both time and space. This study aimed to quantify crop evapotranspiration (ETc) and develop local crop coefficient (Kc) parameters for sweet corn using the eddy covariance system, and to validate irrigation scheduling based on these parameters using the Food and Agriculture Organization of the United Nations (FAO) CROPWAT 8.0 model. The total seasonal ETc values were 141.6 mm, 246.4 mm, and 199.9 mm for the autumn 2022, spring 2023, and autumn 2023 cropping seasons, respectively. Kc values also varied by growth stage, averaging 0.59 and 0.84 for the initial and mid-growth stages. A field validation trial was conducted to compare conventional irrigation with CROPWAT-derived irrigation scheduling. In the spring, yields did not differ significantly between treatments, whereas in the autumn, yields under conventional irrigation were significantly higher than those under the CROPWAT-based treatment. These results suggest that CROPWAT with established Kc values may not be suitable for estimating irrigation amounts during autumn cropping owing to greater variability in Kc values. However, it remains a promising tool for irrigation scheduling in spring cropping when local parameters are applied, suggesting that the fundamental water-requirement information established during the spring season might serve as a useful reference for irrigation decision-making.

Key words:Eddy covariance system, CROPWAT 8.0, Irrigation scheduling, Evapotranspiration

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