Effect of Vermi-compost and Nitrogen Fertilizer on Onion (Allium cepa L.) Yield and Soil Properties under Irrigation in Bena-Tsemay, Southern Ethiopia

@ 2025 | PUBLISHED BY GJR PUBLICATION, INDIA 29 Global Journal of Research in Agriculture & Life Sciences ISSN: 2583-4576 (Online) Volume 05 | Issue 06 | Nov.-Dec. | 2025 Journal homepage: https://gjrpublication.com/gjrals/ Research Article Effect of Vermi-compost and Nitrogen Fertilizer on Onion (Allium cepa L.) Yield and Soil Properties under Irrigation in Bena-Tsemay, Southern Ethiopia *Genanaw Tesema ¹, Shimlies Gizachew ² ¹ South Ethiopia Agricultural Research Institute, Jinka Agricultural Research Center, departments of natural resource directorate P.O. Box 96, Jinka, Ethiopia. ² Hawassa University, College of Agriculture, School of Plant and Horticultural Sciences, Hawassa, Ethiopia. *Corresponding author: Genanaw Tesema South Ethiopia Agricultural Research Institute, Jinka Agricultural Research Center, departments of natural resource directorate P.O. Box 96, Jinka, Ethiopia. ORCID ID: https://orcid.org/0009-0003-2994-2296 Introduction Onion (Allium cepa L.) is among the most important vegetable crops in Ethiopia, valued for its wide consumption and economic contribution, particularly under irrigated production systems (Muluneh, 2016; Gebretsadik & Dechassa, 2016). Despite its significance, the national average yield of onion (9.14 t ha⁻¹) remains far below the global average range of 22–56.4 t ha⁻¹. This low productivity is largely attributed to soil fertility decline and the inappropriate use of fertilizers (CSA, 2017/2018; Fekadu & Dandena, 2006). Nitrogen is a critical nutrient for onion growth and bulb development; however, the blanket fertilizer recommendations currently applied across regions fail to account for site-specific soil fertility variations and crop nutrient demands (Aklilu, 1997; Singh et al., 2013). Integrated Soil Fertility Management (ISFM), which emphasizes the combined use of organic and inorganic nutrient sources, has been recognized as a sustainable strategy to improve soil fertility and enhance crop productivity. Vermicompost, an organic fertilizer produced through the decomposition of organic matter by earthworms, is rich in essential nutrients and beneficial microorganisms that improve soil structure, nutrient availability, and microbial activity (Azarmi et al., 2008; Alemu, 2014). When integrated with mineral fertilizers, vermicompost can enhance nutrient use efficiency and promote sustainable crop production. In Bena-Tsemay District, farmers commonly face challenges related to high fertilizer prices, limited availability, and declining soil fertility, which collectively constrain onion productivity. However, limited research has been conducted on the integrated application of vermicompost and nitrogen fertilizers for onion production under the district’s irrigated farming conditions. Therefore, this study was undertaken to evaluate the effects of vermicompost and nitrogen fertilizer, Abstract Onion (Allium cepa L.) productivity in Ethiopia is limited by continuous cultivation and low soil fertility. Vermicompost (VC) has been proposed to improve soil health, but optimal rates remain unclear. This study in BenaTsemay district, South Omo Zone (May–October 2021), evaluated the effects of VC (0, 2, 4, 6 t ha⁻¹) combined with nitrogen (N) fertilizer (0, 69, 138, 207 kg ha⁻¹) on onion yield and soil properties under irrigation. A randomized complete block design with three replications and sixteen treatments was used. Post-harvest soil analysis showed that VC, N, and their interaction significantly (p<0.01) influenced soil organic matter, N content, and cation exchange capacity, while VC alone improved bulk density and phosphorus availability. The highest bulb yield (24.833 t ha⁻¹) was achieved with 4 t ha⁻¹ VC + 138 kg N ha⁻¹, a 37.5% increase over the control. Economic analysis indicated this treatment provided the highest net benefit (338,684.9 ETB ha⁻¹) with an acceptable marginal rate of return (20,520). Integrating 4 t ha⁻¹ VC with 138 kg N ha⁻¹ is recommended for sustainable onion production in the study area and similar agro-ecologies. Keywords: Onion, Vermi-compost, Nitrogen fertilizer, Soil properties, Cost-benefit analysis. Global J Res Agri Life Sci. 2025; 5(6), 29-38 @ 2025 | PUBLISHED BY GJR PUBLICATION, INDIA 30 applied alone and in combination, on onion (Allium cepa L.) yield, yield components, and selected soil physico-chemical properties under irrigation in Bena-Tsemay District. Additionally, the study assessed the economic feasibility of integrated nutrient management practices to identify sustainable fertilizer options for onion production in the area. Materials and Methods Description of the Study Area The field experiment was conducted during the 2021/2022 cropping season at Woito experimental site of Jinka Agricultural Research Center, located in Bena-Tsemay Woreda, South Omo Zone, Southern Ethiopia. The site lies at 5°18′–5°31′ N and 36°52′–37°05′ E, with an altitude of 660 m a.s.l., about 82 km from Jinka. The area is characterized as hot arid to semi-arid, with erratic rainfall (200–578 mm annually), mean temperatures of 26–40°C, and an annual reference evapotranspiration of 2364 mm (BOFED, 2015). The farming system is predominantly mixed crop–livestock, with maize, sesame, cotton, banana, and vegetables as major crops. Figure 1: Map of the Study Area Experimental Design and Treatments The experiment consisted of 16 treatment combinations arranged in a randomized complete block design (RCBD) with three replications. Treatments included four nitrogen (N) levels (0, 69, 138, and 207 kg N ha⁻¹, applied as urea) and four vermicompost (VC) levels (0, 2, 4, and 6 t ha⁻¹). The plot size was 2.4 × 3 m (7.2 m²), with the central three rows (1.2 × 3 m) used for data collection. The recommended national rates (69 kg N ha⁻¹ and 6 t VC ha⁻¹) were included (EIAR, 2012). Treatment combinations are presented in Table 1. Global J Res Agri Life Sci. 2025; 5(6), 29-38 @ 2025 | PUBLISHED BY GJR PUBLICATION, INDIA 31 Table 1. Treatment combinations used in the experiment Code Treatment Description T1 Control (no fertilizer) T2 2 t VC ha⁻¹ T3 4 t VC ha⁻¹ T4 6 t VC ha⁻¹ T5 69 kg N ha⁻¹ T6 138 kg N ha⁻¹ T7 207 kg N ha⁻¹ T8 2 t VC + 69 kg N ha⁻¹ T9 2 t VC + 138 kg N ha⁻¹ T10 2 t VC + 207 kg N ha⁻¹ T11 4 t VC + 69 kg N ha⁻¹ T12 4 t VC + 138 kg N ha⁻¹ T13 4 t VC + 207 kg N ha⁻¹ T14 6 t VC + 69 kg N ha⁻¹ T15 6 t VC + 138 kg N ha⁻¹ T16 6 t VC + 207 kg N ha⁻¹ Soil Sampling and Analysis Composite soil samples (0–20 cm depth) were collected before planting and post-harvest for selected physico-chemical properties. Analyses included pH (potentiometric method), organic carbon (Walkley & Black, 1934), total N (Kjeldahl method), available P (Olsen et al., 1954), exchangeable K (ammonium acetate method), cation exchange capacity (CEC), and particle size distribution (hydrometer method) following standard laboratory procedures (Jackson, 1973; Tekalign, 1991). Data Collection Growth and yield parameters were recorded from the net plot area. Agronomic traits included plant height and leaf number, while yield components included bulb diameter, bulb length, average bulb weight, and marketable/unmarketable yields. Total bulb yield (t ha⁻¹) was computed from harvested bulbs and expressed on a hectare basis. Economic Analysis Partial budget analysis was performed according to CIMMYT (1988). Adjusted yields (90% of mean yield) were used to calculate gross benefit (GB), total variable cost (TVC), net benefit (NB), and marginal rate of return (MRR). Statistical Analysis Data were subjected to analysis of variance (ANOVA) using SAS software, and treatment means were separated using the least significant difference (LSD) test at 5% probability level. Results and Discussion Baseline Soil Properties and Vermi-Compost Composition Pre-planting soil analysis indicated that the experimental site contained 54% sand, 28% silt, and 18% clay, classifying the soil as sandy loam (Tekalign, 1991), which is suitable for onion production. The high sand content suggests good drainage, favorable for root development and crop growth (Szilas et al., 2002). Global J Res Agri Life Sci. 2025; 5(6), 29-38 @ 2025 | PUBLISHED BY GJR PUBLICATION, INDIA 32 Table 2: Selected physicochemical properties of the experimental soil before planting The soil at the experimental site was slightly alkaline, with a pH value of 7.46, which falls within the suitable range for onion production (6.2–6.8) (Nikus and Mulugeta, 2010). The electrical conductivity (EC) of 0.34 dS m⁻¹ indicated nonsaline conditions (Hazelton and Murphy, 2007). The soil contained 2.43% organic carbon and 4.19% organic matter, suggesting moderate organic matter content (Walkley and Black, 1934; EthioSIS, 2017). Total nitrogen was low (0.10%), whereas available phosphorus was within the medium range (16.08 ppm) (Tekalign, 1991; Olsen et al., 1954). The cation exchange capacity (CEC) was 24.3 cmol(+) kg⁻¹, which is considered moderate and adequate for onion cultivation (EthioSIS, 2017). Overall, these results indicate that the soil, though generally suitable for onion production, requires supplementary organic and inorganic nutrient inputs to achieve optimal yield performance. Table 3: Chemical Properties of vermi-compost Chemical Properties Values Method used Soil reaction (pH (1:2.5 H2O)) 7.08 Glass electrode pH meter (Jackson, 1973) Organic Carbon (%) 10.76 Walkley and Black method (1934) Total Nitrogen (%) 1.62 Kjeldahl method (Jackson, 1973) Available Phosphorous (ppm) 46.08 Olsen method (Olsen et al. 1954) C:N ratio 6.64 Organic carbon divided by TN Where, N = nitrogen, P = phosphorus, C: N = carbon nitrogen, ppm = parts per million. Effects of Different Rates of Vermi-Compost and Nitrogen Fertilizer on Onion Growth The application of different rates of vermi-compost and nitrogen (N) fertilizer had a significant effect on the growth parameters of onion, including plant height, leaf number, and leaf length in the Bena-Tsemay district. The results, summarized in Table 6, show the main effects of these treatments on growth parameters. Table 4: Main effects of different rates of vermi-compost and nitrogen fertilizer application on onion growth parameters Treatment combinations Plant height (cm) Leaf number per plant Leaf length (cm) Vermi-compost (t ha1) 0 44.9c 14.3b 39c 2 47.1b 15.1ab 43.2b 4 49.3a 15.6a 46.5a 6 49.8a 16.0a 46.4a LSD (0.05) 1.8640 0.9327 2.4379 CV (%) 4.75 7.44 6.78 Nitrogen rate (kg ha-1) 0 44.1c 14.0c 41.9b Soil Properties Values Rating Sand (%) 54 Silt (%) 28 Clay (%) 18 Textural Class Sandy loam Bulk Density (g/cm-3) 1.42 Moderately compacted Soil reaction (pH (1:2.5 H2O)) 7.46 Slightly alkaline Organic Carbon (%) 2.43 Medium CEC (cmol (+ ) kg soil–1)) 24.3 Medium Electrical Conductivity (ds cm−1) 0.34 Low Total Nitrogen (%) 0.1 Low Available Phosphorous (ppm) 16.08 Medium Global J Res Agri Life Sci. 2025; 5(6), 29-38 @ 2025 | PUBLISHED BY GJR PUBLICATION, INDIA 33 69 47.1b 15.1b 43.1ab 138 49.8a 15.5ab 44.8a 207 50.1a 16.3a 45.3a LSD (0.05) 1.8640 0.9327 2.43 CV (%) 4.75 7.44 6.78 Means values with different letters in the column are significantly different (p < 0.05). The combined application of vermi-compost and N fertilizer significantly influenced the plant height and leaf length of onions (Table 7). However, the leaf number per plant was not significantly affected by the interaction between these two factors. Table 5: Plant height and leaf length as influenced by the interaction of vermi-compost and nitrogen fertilizer rates Treatment combinations Plant height (cm) Leaf length (cm) 0 (no fertilizer) 38.38i 33.33f 2 VC 42.43h 41.67cde 4 VC 45.95fgh 45.48abc 6 VC 49.71abcdef 47.28ab 69 N 44.61gh 37.44ef 138 N 46.57efg 40.48de 207 N 50.19abcde 44.67abcd 2 VC + 69 N 46.72defg 42.62bcde 2 VC + 138 N 50.81abc 44.00bcd 2 VC + 207 N 48.66bcdefg 44.53bcd 4 VC + 69 N 47.14cdefg 46.66ab 4 VC + 138 N 53.48a 49.43a 4 VC + 207 N 50.47abcd 44.62abcd 6 VC + 69 N 49.81abcde 45.57abc 6 VC + 138 N 48.47bcdefg 45.47abc 6 VC + 207 N 51.05ab 47.28ab LSD (0.05) 3.5493 4.6421 CV (%) 4.75 7.44 Means values with different letters in the column are significantly different (p < 0.05). Table 6: Plant height and leaf length as influenced by the interaction of vermi-compost and nitrogen fertilizer rates Treatment combinations Plant height (cm) Leaf length (cm) 0 (no fertilizer) 38.38i 33.33f 2 VC 42.43h 41.67cde 4 VC 45.95fgh 45.48abc 6 VC 49.71abcdef 47.28ab 69 N 44.61gh 37.44ef 138 N 46.57efg 40.48de 207 N 50.19abcde 44.67abcd 2 VC + 69 N 46.72defg 42.62bcde 2 VC + 138 N 50.81abc 44.00bcd 2 VC + 207 N 48.66bcdefg 44.53bcd 4 VC + 69 N 47.14cdefg 46.66ab 4 VC + 138 N 53.48a 49.43a 4 VC + 207 N 50.47abcd 44.62abcd 6 VC + 69 N 49.81abcde 45.57abc 6 VC + 138 N 48.47bcdefg 45.47abc 6 VC + 207 N 51.05ab 47.28ab LSD (0.05) 3.5493 4.6421 CV (%) 4.75 7.44 Means values with different letters in the column are significantly different (p < 0.05). Global J Res Agri Life Sci. 2025; 5(6), 29-38 @ 2025 | PUBLISHED BY GJR PUBLICATION, INDIA 34 Plant height was significantly influenced by the main effects of vermicompost (VC), nitrogen (N), and their interaction (Tables 5 and 6). The tallest plants (53.48 cm) were recorded from the combined application of 138 kg N ha⁻¹ and 4 t VC ha⁻¹, whereas the shortest plants (38.38 cm) were observed in the control treatment. No significant differences were detected between 2 and 4 t VC ha⁻¹ when combined with either 138 or 207 kg N ha⁻¹. The increase in plant height with higher fertilizer rates could be attributed to improved photosynthetic activity, enhanced cell division and elongation, and better nutrient availability resulting from the synergistic effects of organic and inorganic inputs (Surindra, 2009; Kokobe et al., 2013; Negasi et al., 2017; Yohannes et al., 2017). Leaf number per plant was significantly affected by the main effects of nitrogen (N) and vermicompost (VC), but their interaction was not significant. Increasing N application rates enhanced leaf number by 86.6%, likely due to improved chlorophyll synthesis and photosynthetic efficiency. Similarly, VC application increased leaf number by 88.6%, which may be attributed to the supply of essential micronutrients and plant growth-promoting substances that stimulated greater vegetative growth and overall plant vigor (Gupta, 2005; Melaku, 2010; Abdisa, 2008). These positive growth responses established a strong foundation for enhanced yield components such as bulb diameter, average bulb weight, and total yield of onion under the irrigated conditions of Bena-Tsemay District. Table 7: Main effects of different rates of vermi-compost and Nitrogen fertilizer rates on yield parameters of onion. Treatment combinations Bulb diameter (cm) Average bulb weight (g) Marketable bulb yield (t ha⁻¹) Unmarketable bulb yield (t ha⁻¹) Total bulb yield (t ha⁻¹) Nitrogen rate (Kg ha⁻¹) 0 4.90c 397.92b 11.52c 2.84 14.27c 69 5.29b 415.14b 14.39b 2.83 17.32b 138 5.75a 477.67a 17.44a 2.47 19.92a 207 5.65a 454.16a 16.83a 3.17 19.74a LSD 0.3 24.53 1.12 NS 1.05 CV (%) 6.91 6.85 9.09 31.9 7.17 Vermicompost rate (t ha⁻¹) 0 4.88b 370.06c 11.63c 2.57 13.89c 2 5.18b 409.82b 13.56b 2.94 16.49b 4 5.80a 473.00a 17.01a 3.17 20.17a 6 5.73a 492.00a 17.97a 2.64 20.70a LSD (0.05) 0.3 24.535 1.12 NS 1.05 CV (%) 6.91 6.85 9.09 31.9 7.17 Means values with different letters in the column are significantly different (p<0.05). Whereas mm=millimeter, N=nitrogen, VC=vermincompost, t ha-1=ton per hectare, kg ha-1= kilo gram per hector, LSD= least significant difference, CV (%) =coefficient of variance in percent The combined applications of vermi-compost and Nitrogen fertilizer rates had significantly affected Bulb diameter, Average bulb weight, Marketable bulb yield and Total bulb yield of onion that was grown at Bena-Tsemay district except that of unmarketable yield. The overall results were depicted below in (Table 8). Global J Res Agri Life Sci. 2025; 5(6), 29-38 @ 2025 | PUBLISHED BY GJR PUBLICATION, INDIA 35 Table 8: Interaction effects of different rates of vermi-compost and Nitrogen fertilizer rates on yield parameters of onion. Treatment combinations BD (cm) ABW (g) MBY (t ha-1) UMBY(t ha-1) TBY (t ha-1) 0 (no fertilizer) 3.91f 309h 6.93i 2.7 9.3j 2 VC 4.58e 359.67g 10.77h 2.7 13.47i 4 VC 5.49bc 430de 13.13fg 3.1 16.23efgh 6 VC 5.66bc 493b 15.23ef 2.87 18.10def 69 N 4.76de 344.91gh 12.69fgh 1.59 14.35hi 138 N 5.37bcd 370.33fg 12.67gh 2.37 15.03ghi 207 N 5.50bc 456bcde 14.23efg 3.63 16.87efg 2 VC + 69 N 5.29cd 424de 13.23fg 2.87 16.10fgh 2 VC + 138 N 5.51bc 442.33cde 14.43efg 3.03 17.47def 2 VC + 207 N 5.37cd 413ef 15.80de 3.15 18.93cd 4 VC + 69 N 5.59bc 453bcde 14.1fg 4.17 18.27de 4 VC + 138 N 6.37a 544a 22.67a 2.17 24.83a 4 VC + 207 N 5.78abc 465bcd 18.13bc 3.23 21.37b 6 VC + 69 N 5.55bc 438.67cde 17.53cd 2.7 20.57bc 6 VC + 138 N 5.76abc 554a 20b 2.33 22.33b 6 VC + 207 N 5.98ab 482.33bc 19.13bc 2.67 21.80b LSD0.05 0.5836 46.718 2.1384 NS 1.9981 CV (%) 6.91 6.85 9.09 31.9 7.17 Means values with different letters in the column are significantly different (p<0.05). Whereas mm=mili meter, BD=bulb diameter, ABW=average bulb weight,MBY=marketable bulb yield,UMBY=unmarketable bulb yield, TBY=total bulb yield N=nitrogen, VC=vermi-compost, in t ha-1=ton per hectare, N in kg ha-1= kilo gram per hectare, LSD= least significant difference, CV (%) =coefficient of variance in percent. The combined application of vermicompost (VC) and nitrogen (N) significantly improved onion yield and yield components. The highest bulb diameter (6.37 cm) was recorded under 138 kg N ha⁻¹ + 4 t VC ha⁻¹, whereas the smallest (3.91 cm) was obtained from the control treatment. This increase in bulb size could be attributed to enhanced nutrient availability, improved photosynthetic efficiency, and auxin-mediated cell expansion and growth (Soni et al., 2016; Yohannes et al., 2017). Similarly, the highest average bulb weight (554 g) was obtained from the 138 kg N ha⁻¹ + 6 t VC ha⁻¹ treatment, reflecting improved nutrient uptake and efficient assimilate translocation to the bulbs (Gebremicael et al., 2017; Kokobe et al., 2013). Marketable bulb yield was also maximized (22.67 t ha⁻¹) at 138 kg N ha⁻¹ + 4 t VC ha⁻¹, while unmarketable yield was not significantly affected by the treatments, indicating that bulb quality losses may be influenced more by pests, diseases, or varietal characteristics than by fertilizer management. Total bulb yield followed a similar trend, with the highest value (24.83 t ha⁻¹) obtained under 138 kg N ha⁻¹ + 4 t VC ha⁻¹. This result demonstrates the synergistic effect of integrating organic and inorganic nutrient sources in enhancing onion productivity under irrigated conditions in Bena-Tsemay District (Abrha et al., 2015; Yadav et al., 2015). Overall, integrating vermi-compost with nitrogen fertilizer effectively improves onion yield and quality by enhancing growth, nutrient uptake, and soil health, with 138 kg N ha⁻¹ + 4 t VC ha⁻¹ identified as the optimal combination for the Bena-Tsemay district. Partial Budget Analysis Partial budget analysis evaluated the economic feasibility of vermi-compost and nitrogen fertilizer treatments by comparing total variable costs and net benefits (CIMMYT, 1988). Variable costs included N fertilizer and labor for VC preparation, while fixed costs were excluded. Onion market price was 17 Birr kg⁻¹. Results showed that combined VC and N applications produced the highest net benefits, indicating that integrating organic and inorganic fertilizers is both agronomic ally and economically advantageous. Global J Res Agri Life Sci. 2025; 5(6), 29-38 @ 2025 | PUBLISHED BY GJR PUBLICATION, INDIA 36 Table 9: Partial Budget Analysis for Treatments Treatments 10%AMBY (kg ha-1) Revenue (ETB) TVC TCP (ETB/ha) GM(ETB/ha ) NB(ETB/ha) BCR (%) 0 8370 192,510 0 0 142,290 142,290 0.0 2 VC 12,120.3 278,766.9 5,000 5,000 201,045.1 196,045.1 39.21 4 VC 14,609.7 336,023.1 10,000 10,000 238,364.9 228,364.9 22.84 6 VC 16,290 374,670 15,000 15,000 261,930 246,930 16.46 69 N 12,912.3 296,982.9 5,315 5,315 214,194.1 208,879.1 39.30 138 N 13,529.7 311,183.1 10,630 10,630 219,374.9 208,744.9 19.64 207 N 15,180.3 349,146.9 15,945 15,945 242,120.1 226,175.1 14.18 2 VC + 69 N 14,490 333,270 10,315 10,315 236,015 225,700 21.88 2 VC + 138 N 15,720.3 361,566.9 15,630 15,630 251,615.1 235,985.1 15.10 2 VC + 207 N 17,033.4 391,768.2 20,945 20,945 268,622.8 247,677.8 11.83 4 VC + 69 N 16,440.3 378,126.9 15,315 15,315 264,170.1 248,855.1 16.25 4 VC + 138 N 22,349.7 514,043.1 20,630 20,630 359,314.9 338,684.9 16.42 4 VC + 207 N 19,230.3 442,296.9 25,945 25,945 300,970.1 275,025.1 10.60 6 VC + 69 N 18,510.3 425,736.9 20,315 20,315 294,360.1 274,045.1 13.49 6 VC + 138 N 20,099.7 462,293.1 25,630 25,630 316,064.9 290,434.9 11.33 6 VC + 207 N 19,620 451,260 30,945 30,945 302,595 271,650 8.78 Where, ETB=Ethiopian Birr, TVC=Total variable cost and MRR=marginal rate of return, D=Dominant Treatment, ND= non-dominated Treatment AMBY=Adjusted marketable bulb yield, VC=vermi-compost in t ha-1, N=nitrogen in kg ha-1. Partial budget analysis revealed that marketable bulb yield and profitability were significantly influenced by the combined application of vermicompost (VC) and nitrogen (N) fertilizer. The highest net return (338,685 ETB ha⁻¹) was achieved with 4 t VC ha⁻¹ + 138 kg N ha⁻¹, followed by 6 t VC + 138 kg N ha⁻¹ (290,435 ETB ha⁻¹), 4 t VC + 207 kg N ha⁻¹ (275,025 ETB ha⁻¹), and 6 t VC + 207 kg N ha⁻¹ (271,650 ETB ha⁻¹). The lowest net return (142,290 ETB ha⁻¹) was recorded in the unfertilized control. Marginal rate of return (MRR) analysis indicated that the integration of organic and inorganic fertilizers maximizes profitability relative to cost, providing guidance for cost-effective input decisions (CIMMYT, 1988). Dominance analysis further confirmed that treatments combining high net benefits with reasonable costs are the most economically viable, whereas treatments with lower returns relative to costs were dominated. Overall, the results demonstrate that integrating vermicompost with nitrogen fertilizer is both profitable and economically effective for onion production under irrigated conditions. Table 10: Net Benefits and Marginal Rate of Return for Onion Production Response to N and Vermi-Compost (2021/2022) Treatments 10% AMBY (kg ha-1) TVC (ETB ha-1) Net Benefit (ETB ha-1) Dominance Analysis MRR (%) 0 8370 0 142,290 - - 2 VC 12,120.3 5,000 196,045 ND 1075.1 69 N 12,912.3 5,315 208,879.1 ND 415.9 4 VC 14,609.7 10,000 228,364.9 ND D 2 VC + 69 N 14,490 10,315 225,700 D D 138 N 13,529.7 10,630 208,744.9 D D 6 VC 16,290 15,000 246,930 ND 44 4 VC + 69 N 16,440.3 15,315 248,855.1 ND 611 2 VC + 138 N 15,720.3 15,630 235,985.1 D D 207 N 15,180.3 15,945 226,175.1 D D 6 VC + 69 N 18,510.3 20,315 274,045.1 ND 1095 4 VC + 138 N 22,349.7 20,630 338,684.9 ND 20520 2 VC + 207 N 17,033.4 20,945 247,677.8 D D 6 VC + 138 N 20,099.7 25,630 290,434.9 D D 4 VC + 207 N 19,230.3 25,945 275,025.1 D D 6 VC + 207 N 19,620 30,945 271,650 D D Global J Res Agri Life Sci. 2025; 5(6), 29-38 @ 2025 | PUBLISHED BY GJR PUBLICATION, INDIA 37 Where, ETB=Ethiopian Birr, TVC=Total variable cost and MRR=marginal rate of return, D=Dominant Treatment, ND= non-dominated Treatment AMBY=Adjusted marketable bulb yield, VC=vermi-compost in t ha-1, N=nitrogen in kg ha-1. Net benefit analysis showed that non-dominated treatments 2 t ha⁻¹ VC, 69 kg ha⁻¹ N, 4 t ha⁻¹ VC, and combinations such as 4 t ha⁻¹ VC + 69 kg ha⁻¹ N, 6 t ha⁻¹ VC + 69 kg ha⁻¹ N, and 4 t ha⁻¹ VC + 138 kg ha⁻¹ N offered increasing net benefits and are recommended for onion production. Dominated treatments, including higher-input combinations, incurred greater costs without proportional returns. The highest marginal rate of return (MRR, 20520%) was achieved with 4 t ha⁻¹ VC + 138 kg ha⁻¹ N, while the lowest (44%) occurred with 6 t ha⁻¹ VC. For non-dominated treatments, each 1 ETB invested returned 4.15–205.2 ETB. Overall, 4 t ha⁻¹ VC + 138 kg ha⁻¹ N provided the maximum net benefit (338,684.9 ETB ha⁻¹) and MRR, exceeding the minimum acceptable MRR of 100%, making it the most profitable option for farmers. Summary and Conclusion The combined application of vermi-compost and nitrogen fertilizer significantly improved onion growth, yield, and soil properties in Bena-Tsemay district. Among treatments, 4 t ha⁻¹ vermi-compost with 138 kg ha⁻¹ N produced the highest marketable yield (22.67 t ha⁻¹) and net benefit (338,684.9 ETB ha⁻¹) with the greatest marginal rate of return. Vermicompost enhanced soil organic matter, total nitrogen, cation exchange capacity, and reduced bulk density, while N fertilizer boosted yield components. These results demonstrate that integrating organic and inorganic fertilizers is an effective strategy for sustainable onion production. Application of 4 t ha⁻¹ vermi-compost combined with 138 kg ha⁻¹ N is recommended for maximizing yield and profitability, though multi-season trials are advised to confirm consistency. Authors Contribution Genanaw Tesema; conceptualization, information search and writing the manuscript. The research proposal was prepared and the final manuscript was revised by Genanaw Tesema and Shimlies Gizachew. Acknowledgements The authors thank South Ethiopia Agricultural Research Institute (SEARI) for financially supporting the field experiment. And also, very grateful to Jinka Agricultural Research Center for the analysis of the soil parameters and for the facilitation of the vehicle and other accommodations to conduct the field experiment. Conflict of Interest The authors declare that there is no conflict of interest regarding the publication of this article. References 1. Abdisa, T. (2008). Effect of nitrogen and organic amendments on growth and yield of vegetables. Ethiopian Journal of Horticultural Science, 6(2), 12–20. 2. Abrha, B., Negasi, A., & Melaku, K. (2015). Effect of integrated nutrient management on onion yield and quality. Journal of Horticultural Research, 23(1), 45–52. 3. Aklilu, H. (1997). Fertilizer recommendations for major crops in Ethiopia. Addis Ababa: Ethiopian Agricultural Research Organization. 4. Alemu, D. (2014). 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