Response of Onion to Application of UREA and NPS Fertilizer Rates Under Irrigation in Mareko District, Central Ethiopia

Background and Objective: In the Central Ethiopian Region, onions are one of the most significant vegetable crops that are grown with irrigation. Applying fertilizer is a crucial input to boost vegetable yields, especially onion yields. The study aimed to determine the ideal rate of NPS and UREA fertilizer under irrigation. Materials and Methods: It was conducted in Mareko, Guraghe Zone in 2017 and 2018. The treatments consisted of five UREA rates (0, 50, 100, 150 and 200 kg/ha) and five NPS fertilizer rates (0, 50, 100, 150 and 200 kg/ha). Factorial combination treatments were arranged in a randomized complete block design with three replications. Data on plant height, bulb diameter and total yield were recorded and analyzed using SAS 9.3 software. Results: The interaction effect of NPS*UREA*Yr revealed that non- significant on plant height, bulb diameter and total yield of onion combined over two years. Based on the mean performance 100 kg NPS and 100 Kg UREA fertilizer gave the highest plant height, bulb diameter and yield was obtained while; the lowest was in the control. According to partial budget analysis, the rate of 100 kg NPS and 100 kg /ha UREA fertilizer increases the profitability of onion crops for the farmers. Conclusion: The application of 100 kg/ha NPS increased the fruit yield by 3.4 and 7.63 tones over the control combined over theyear. Hence, the application of 100 kg/ha NPS and 100 kg/ha UREA is suitable for onion production under irrigation in the study area and similar agroecologies.