Yield Response of Onion (Allium cepa L.) to Integrated Application of Inorganic (NPS/Urea) and Organic Fertilizers at Fafan Research Center, Somali Region, Ethiopia

Abstract

Onion (Allium cepa L.) is an economically important vegetable in Ethiopia, especially in irrigated areas like the Somali Region. However, its productivity remains low due to declining soil fertility and poor nutrient management. This study was conducted during the 2023/2024 cropping season at the Golajo site of the Fafan Agricultural Research Center to evaluate the effects of integrated nutrient management on the growth and yield of onion. A field experiment was laid out in a randomized complete block design (RCBD) with three replications, testing factorial combinations of three NPS/urea fertilizer rates (0, 50/50, 100/100, and 150/150 kg/ha) and three farmyard manure (FYM) levels (0, 10, and 20 t/ha). The onion variety ‘Hadramout’ was used. Results showed that both NPS/urea and FYM significantly influenced phenological traits, growth parameters, and yield components. The highest plant height (64.78 cm), leaf number (15.58), leaf length (55.13 cm), and average bulb weight (135.3 g) were recorded with the highest combined fertilizer rates. The maximum total bulb yield (17.34 t/ha) and marketable yield (17.21 t/ha) were also obtained under this treatment. Conversely, control plots without fertilizer showed the lowest values across most parameters. The findings highlight the importance of integrated nutrient management in enhancing onion productivity and suggest that combining 150/150 kg/ha of NPS/urea with 10–20 t/ha of FYM is an effective strategy. To validate these findings, additional trials across multiple locations and seasons are recommended. The integrated use of organic and inorganic fertilizers offers a sustainable strategy for enhancing soil fertility, increasing crop yield, and improving farm profitability.