Integrated effects of furrow irrigation systems and irrigation regimes on water productivity of onion (Allium cepa L.) crop in a semi-arid area.

Dwindling water resources with inept field water management impends sustainable agricultural production in semi-arid areas of Ethiopia. Thus, the adaption and adoption of improved irrigation water running lines are indispensable and imperative to recuperate water productivity in areas where water resources are inadequate. The ground experiments were pointed to elucidate the weight of conventional, alternate, and fixed furrow irrigation systems under irrigation levels of 100 %, 70 %, and 40 % of crop evapotranspiration (ETc) on onion growth, yield, water productivity, and economic return in Alage, Central, Ethiopia. The field trials were conducted at nine treatments arranged in a randomized complete block design with three replications and water was managed at fixed intervals with variable depth approach. The result illustrated that furrow systems in conjunction with irrigation levels had a weighty pertain (P < 0.05) on onion growth, yield, water productivity, and economic return. The highest yield of 30.75 ton ha^-1 was achieved at conventional furrow irrigation with 100%ETc dictated to zero water saving subsequently, the crop and irrigation water productivity dropped with the values of 6.86 and 5.61 kg m^-3 respectively. The diminished yield of 6.39 ton ha^-1 obtained at fixed furrow irrigation with 40%ETc conquered the saved water output lastly, the crop and irrigation water productivities demoted with values of 6.87 and 5.70 kg m^-3 respectively. Nevertheless, 24.93ton ha^-1 of ideal yield was obtained under alternative furrow irrigation with 100%ETc and the 50 % hoarded water was higher than the yield decline. Consequently, the crop and irrigation water productivities rose with values of 10.96 and 9.09 kg m^-3 respectively. Eventually, the saved water opened for 0.03ha extra irrigable area that will onward to the highest total expected yield of 37.40 ton ha^-1 as compared with all other treatments. Under conventional furrow irrigation with 100%ETc, the obtained yield dominated the wastewater accordingly, the highest net return of 668484ETB ha^-1 and benefit-cost ratio of 3.63 was achieved. Besides, the unbearable yield penalty under fixed furrow with 40 % headed to negative net return and lowest befit cost ratio as related with other treatments. However, further economic results confirmed that the 50 % saved water under alternative furrow with 100 % can recompense for the net return reduction that will make this trial combination preferable as compared with other treatments. Other results also recommended that, under water-limiting and inefficient field water governing conditions, alternative furrow irrigation with 100%ETc can be the ideal blend to enhance water productivity in semi-arid regions of Ethiopia and elsewhere that share similar agroclimatic conditions.