Seasonal Yield Response Factor for Red Bombay Onion (Allium cepa L.) Variety in Arba Minch, Ethiopia

Background: For better water resources management in the areas of water shortage for crop production, deficit irrigation is very important. The understanding of the yield response factor to water deficit is crucial for efficient irrigation water management. Deficit irrigation for studying yield response factors is always practiced in the way of stressing the demand of the crops. The present study was done for the determination of the seasonal yield response factor of red Bombay onion variety under Arba Minch agro climate condition. Furthermore, it also examined the effect of furrow irrigation systems on the seasonal yield response factor. Methods: The experiment was conducted from August to November 2019. The experiment had six treatments, which were the combination of two furrow irrigation systems and three irrigation levels. Data were collected for soil moisture before and after each irrigation and bulb yield. The seasonal yield response factors were determined through simple linear regressions using SPSS software. Result: When considering the furrow irrigation system as a factor, the seasonal yield response factor for alternate furrow irrigation system was 1.18 while for paired row furrow irrigation system was 1.07. This red Bombay variety of onion clearly shows more sensitive to water stress for alternative furrow irrigation systems than paired row furrow irrigation systems. Therefore, in the area of water shortage paired row furrow irrigation system is better than alternate furrow irrigation system. The seasonal yield response factor as a wall for red Bombay onion variety in Arba Minch agro-ecological condition was 1.12. Therefore, the red Bombay onion variety in Arba Minch agroclimate condition was sensitive to water stress.

Effect of furrow irrigation methods and deficit irrigation levels on yield and water productivity of onion (Allium cepa L.) at Amibara, Middle Awash Valley, Ethiopia.

Background: Deficit irrigation is one of the techniques used to enhance water productivity without significant yield loss in semiarid areas. Methods: A field experiment was conducted at Werer, Middle Awash Valley during the dry season of 2017/18, 2018/19 and, 2019/20 for three consecutive years to investigate the effects of deficit irrigation levels and furrow irrigation methods on onion yield and water productivity. Split plot design with three replications, in which the irrigation methods (Conventional, Fixed and Alternate Furrow) were assigned to the main plot and the three deficit levels (100% ETc, 75% ETc and 50% ETc), were in the sub-plot. Results: Results indicate that marketable onion bulb yield and water productivity were highly affected by the interaction effect of furrow irrigation methods and irrigation levels (p < 0.05). The highest bulb yield (17580.43 kg ha-) and water productivity (11.79 kg/m3) were obtained from conventional furrow irrigation method with100% ETc and alternate furrow irrigation with 50% ETc respectively. Considering water saved and maximum yield, Onion irrigated by AFI 100% ETC resulted in a 15% yield reduction with up to 50% irrigation water saving as compared to CFI 100% ETc. Conclusion: The present study suggests that, under water limiting conditions, adopting alternate furrow irrigation with 100% ETc can be an alternative to increase water productivity without significant yield reduction.

Maize Yield and Water Use Efficiency Under Different Irrigation Levels and Furrow Irrigation Methods in Semiarid, Tropical Region

Water scarcity is the major limiting factor of agricultural production and productivity in the central rift valley of Ethiopia. Best use of limited water is necessary through water conservation practices. Field experiments were conducted during the dry cropping seasons of 2016 and 2017 on clay loam soil at experimental farm of Melkassa Agricultural Research Centre to evaluate the impact of irrigated furrow methods and deficit irrigation applications on maize (Zea mays) yield and water use efficiency. The study involved three furrow irrigation methods (conventional, fixed, and alternate furrow irrigation) and three irrigation application levels (100%ETc, 75%ETc, and 50%ETc). Furrow irrigation system as main plot and irrigation levels as sub-plot were arranged in split plot design with three randomized complete blocks each year. Greatest yield was obtained under conventional furrow irrigation supplied with 100%ETc of water. Water use efficiency under the same treatment was lesser and shows no significant difference with fixed furrow irrigation and 50%ETc application. Greatest water use efficiency of maize was obtained from alternate furrow irrigation under 75%ETc application and showed no significant difference with 100%ETc application. However, grain yield reduction under 75%ETc applications was very much higher than 100%ETc application. Water saved as a result of 100ETc and 75%ETc applications were 50% and 62.5%, respectively. Therefore, scheduling irrigation time for maize in the central rift valley of Ethiopia and similar semiarid environments could be 100%ETc or 75%ETc application using alternate furrow irrigation. The 75%ETc application has an advantage over 100%ETc applications in saving more water and hence could be applied when water availability is severely limited.

Yield and Water Use Efficiency of Potato under Alternate Furrows and Deficit Irrigation

The benefits of water-saving techniques such as alternate furrow and deficit irrigations need to be explored to ensure food security for the ever-increasing population within the context of declining availability of irrigation water. In this regard, field experiments were conducted for 2 consecutive dry seasons in the semiarid region of southwestern Ethiopia and investigated the influence of alternate furrow irrigation method with different irrigation levels on the yield, yield components, water use efficiency, and profitability of potato production. The experiment comprised of 3 irrigation methods: (i) conventional furrow irrigation (CFI), (ii) alternate furrow irrigation (AFI), and (iii) fixed furrow irrigation (FFI) combined factorially with 3 irrigation regimes: (i) 100%, (ii) 75%, and (iii) 50% of the potato water requirement (ETC). The experiment was laid out in randomized complete block design replicated thrice. Results revealed that seasonal irrigation water applied in alternate furrows was nearly half (170 mm) of the amount supplied in every furrow (331 mm). Despite the half reduction in the total amount of water, tuber (35.68 t ha−1) and total biomass (44.37 t ha−1) yields of potato in AFI did not significantly differ from CFI (34.84 and 45.35 t ha−1, respectively). Thus, AFI improved WUE by 49% compared to CFI. Irrigating potato using 75% of ETC produced tuber yield of 35.01 t ha−1, which was equivalent with 100% of ETC (35.18 t ha−1). Irrigating alternate furrows using 25% less ETC provided the highest net return of US$74.72 for every unit investment on labor for irrigating potato. In conclusion, irrigating alternate furrows using up to 25% less ETC saved water, provided comparable yield, and enhanced WUE and economic benefit. Therefore, farmers and experts are recommended to make change to AFI with 25% deficit irrigation in the study area and other regions with limited water for potato production to improve economic, environmental, and social performance of their irrigated systems.

Effect of Deficit Irrigation on Yield and Water Use Efficiency of Maize at Selekleka District, Ethiopia

Irrigation water availability is diminishing in many areas of the Ethiopian regions, which require many irrigators to consider deficit-irrigation strategy. This study investigated the response of maize (Zea mays L.) to moisture deficit under conventional, alternate and fixed furrow irrigation systems combined with three irrigation amounts over a two years period. The field experiment was conducted at Selekleka Agricultural Research Farm of Shire-Maitsebri Agricultural Research Center. A randomized complete block design (RCBD) with three replications was used. Irrigation depth was monitored using a calibrated 2-inch throat Parshall flume. The effects of the treatments were evaluated in terms of grain yield, dry above-ground biomass, plant height, cob length and water use efficiency. The two years combined result indicated that net irrigation water applied in alternate furrow irrigation with full amount irrigation depth (100% ETc AFI) treatments was half (3773.5 m3/ha) than that of applied to the conventional furrow with full irrigation amount (CFI with 100% ETc) treatments (7546.9 m3/ha). Despite the very significant reduction in irrigation water used with alternate furrow irrigation (AFI), there was insignificant grain yield reduction in maize(8.31%) as compared to control treatment (CFI with100% ETc). In addition, we also obtained significantly (p<0.001) higher crop water use efficiency of 1.889 kg/m3 in alternate furrow irrigation (AFI), than that was obtained as 0.988 kg/m3 in conventional furrow irrigation (CFI). In view of the results, alternate furrow irrigation method (AFI) is taken as promising for conservation of water (3773.5 m3/ha), time (23:22'50" hours/ha), labor (217.36 USD/ha) and fuel (303.79 USD/ha) for users diverting water from the source to their fields using pump without significant trade-off in yield.