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AbstractEvaluating and comparing two different irrigation scheduling methods like soil moisture (SM) and evapotranspiration (ET)-based irrigation scheduling methods were assessed scientifically to maximize tomato yield, especially in areas where restricted irrigation facilities are available. The experimental design was arranged in a Randomized Complete Block Design (RCBD) with 100%, 75%, and 50% water requirements with three replications. The water was applied to furrows using Randomized Block Design (RBC) flume with an inflow rate of 1.62 l/s. The total amount of water applied in SM- and ET-based methods were 229.1 mm and 280 mm, respectively. The collected data were analyzed using ANOVA (statistical software) at 5% significance level. Values on agronomic characteristics, yield attributes, and yield were determined for those two methods. T1–T6 are the total treatments used in this research. Out of which, T1, T2, and T3 are taken as SM-based represented for 100%, 75%, and 50% of requirements and T4, T5, and T6 as ET-based represented for the same percentage of requirements. The results did not illustrate a huge difference in yield potential. The highest net benefit on yield was obtained at T2 (SM-based), whereas the lowest in T6 (ET-based). It was also observed that SM-based method saved around 18.2% of irrigation water compared to ET-based approach. Therefore, to cultivate high water demanding crops such as tomato in water scarce areas, SM-based irrigation scheduling method is comparatively better than ET-based as far as yield is concerned.

AbstractLack of irrigated water poses a threat in arid and semi-arid areas. Hybrid irrigation system has become an obligatory to save water and increase productivity. Deficit irrigation scheduling is a recent innovative approach of water-saving method. An experiment was conducted to estimate the irrigation interval and find an amicable solution by optimum deficit irrigation level at Arba Minch of southern Ethiopia using conventional furrow irrigation system. The treatments comprised 75%, 50% and 25% of irrigation requirement and four growth stages (initial, development, bulb formation, and late), which were considered in random complete block design with three replications. Refilling was commenced when 25% of Readily Available Water (RAW) depletion at the full irrigation was observed. The irrigation intervals at growth stages were 4, 6, 4, and 3 days, respectively, with an overall irrigation interval of 3 days. The net and gross irrigation of the crop were 311.80 mm and 445.42 mm, respectively. The highest crop phenology and yield were obtained by applying Irrigation Requirement (IR) of a maximum 100% and minimum at 25%. The maximum yield of 25.88 ton/ha was obtained from full irrigation which hardly affects the yield of 25.70 ton/ha obtained from 75%IR at late growth stages. Therefore, application of 100%IR at 3 days interval was assessed as economically productive. However, 50%IR at 3 days interval can be an option when there is a constraint of water supply. The findings will be useful for irrigation water management to maximize crop yields with limited water and unlimited land resources.