Determination of Optimal Irrigation Scheduling for Onion Under Furrow Irrigation Method in Eastern Hararghe Zone, Ethiopia

Efficient irrigation water management is critical for optimizing crop productivity and ensuring the sustainable use of limited water resources, particularly in semi-arid regions. This study was conducted during the 2022/23 and 2023/24 cropping seasons at Kombolcha District, East Hararghe Zone, Oromia regional state, Ethiopia. The purpose of the activity was to create optimal irrigation regimes (when and how much to irrigate) for onions and evaluate the effect of different irrigation timings on the water productivity and yield of the onion crop. The results showed that irrigation water, maximum irrigation frequency, and short irrigation intervals were achieved by scheduling irrigation at 60% of the ASMDL treatment. The next maximum irrigation frequency was obtained by scheduling irrigation at 80% of ASMDL treatment. Minimum irrigation frequency and minimum water consumed by scheduling irrigation at 140% ASMDL treatment. The results show that the maximum onion yield was obtained by scheduling irrigation at 60% of ASMDL treatment, followed by 80% ASMDL treatment. Statistically, there is no significant difference between 60% ASMDL and 80% ASMDL treatments in terms of onion yield. Maximum water productivity was obtained by scheduling irrigation at 80% ASMD treatment followed by 60% ASMDL treatment. Statistically, there is no significant difference between 60%, 100%, and 120% ASMDL treatments in terms of onion water productivity. The minimum water productivity was reached by scheduling irrigation at 140% ASMDL treatment. So, scheduling irrigation at 80% ASMDL is recommended for onion with 5-day, 6-day, 7-day, and 10-day irrigation intervals at initial, development, mid, and maturity stages of onion, respectively.