Proper irrigation scheduling can help to ensure judicial use of water resources, improve crop yield, reduce the cost of irrigation, and minimize the risks of water management–related problems such as waterlogging and salinization. This paper aims to identify the most suitable irrigation scheduling practices for the Fincha sugarcane plantation using the modeling and simulation model, CROPWAT, and statistical methods. All data required for modeling and simulation in the model were collected, and the model was run for 22 selected irrigation scheduling scenarios. The irrigation scheduling scenarios were formulated by combining different options of scheduling from four major irrigation scheduling methods: fixed or rigid schedule, partially flexible schedule, mixed schedule, and on‐demand schedule. The model was run for the 22 selected scheduling scenarios and three replications across seasons to estimate the performance of irrigation scheduling. Four indicators—the efficiency of irrigation schedule (EIS), the deficiency of irrigation schedule (DIS), the efficiency of rain (ER), and the percentage yield reduction (YR) simulated in the model—were used to assess the performance of irrigation scheduling. The correlation analysis was carried out to identify the nature of the relationship among the performance indicators. In addition, the analysis of variances (ANOVA) was carried out to check if the irrigation scheduling scenarios have a significant effect on irrigation scheduling performance. Furthermore, a multiple least significant difference (MLSD) test was carried out to compare the mean values of performance indicators. All the analyses were carried out using R statistical software. It is found that the EIS and the ES are highly correlated, while the DIS and YR are significantly correlated. The ANOVA shows that the irrigation scheduling scenarios have a significant effect on performance indicators. The MLSD shows on‐demand scheduling, and mixed irrigation scheduling showed the highest, equal, and consistent performance for all performance indicators. Considering manageability under the existing design, the mixed irrigation scheduling scenarios consisting of predetermined depth of applications varying with growth stage and irrigation interval based on soil moisture deficit can generally be considered optimal for both soils in the Fincha sugar estate. An average irrigation schedule efficiency of 90.9% in Luvisol and 100% in Vertisol, as well as an irrigation rain efficiency of 61.7% in Luvisol and 65% in Vertisol, can be attained with the mixed irrigation scheduling scenarios. In addition, the deficiency irrigation schedule and YR can be kept at 0.0% for both soils. Therefore, it is recommended that the sugar estate shall implement the identified mixed irrigation scheduling practices for optimal yield and water‐use efficiency. This approach can be used for the identification of optimal irrigation schedules at reasonable accuracy. Further study focusing on the validation of the results might be needed to address the inherent limitations of modeling and simulations in estimating performance indicators.
Solomon Mulugeta (Thu,) studied this question.