This study was conducted during the dry season of 2017/2018 at the Ilu Gelan district Western Shewa zone of Oromia Regional State to evaluate the impacts of furrow dimensions on yield and water productivity of onion. Climatic, plant and soil factors were used for the calculation of monthly crop water and irrigation requirements and results compared with actual performance of the irrigation system. The experiment was laid out in a randomized complete block design with three treatments replicated four times. The experimental treatments including farmer practice or T1 (farmer practice with top width of 23cm, bottom width of 13cm and depth of 11cm without determined flow rate), T2 (Furrow with top width of 45cm, bottom width of 20cm and depth of 12cm with determined flow rate) and T3 (Furrow with top width of 35cm, bottom width of 14cm and depth of 10cm with determined flow rate) having a plot size of 8mx5m with spacing of 0.5m x 1m between plots and replications respectively. The application efficiency in the treatment T2 was highest (75.87%) in comparison to other treatments. The lowest (56.17%) application efficiency was found in T1 i.e. farmer practice. Distribution efficiency was highest (89%) in treatment T2 and lowest (81%) in treatment T1. The best treatment in terms of water productivity and yield of onion was T2 which were (5.2kg/m3) and (1952kg/ha) respectively. The lowest result was obtained from T1 which were (3.11kg/m3) and (15088kg/ha) respectively. There were significance differences in plant height among all treatments at significance level of 5%. The highest (41.525cm) was recorded from T2 and the lowest (39.275cm) was obtained from T1. Further research covering all soil types is recommended to be more inclusive.
Keywords: Furrow irrigation; furrow dimension; grain yield; irrigation efficiency; onion; water productivity