GROWTH, YIELD, QUALITY , AND ECONOMIC EVALUATION OF NITROGEN AND VERMICOMPOST INTEGRATION IN THREE TOMATO (Lycopersicon esculentum Mill. ) VARIETIES

Abstract

Tomato is a major vegetable crop of high nutritional and economic value, yet its productivity in Ethiopia remains low mainly because growers apply nitrogen and VC inefficiently under declining soil fertility. Integration of vermicompost and mineral nitrogen enhanced soil health (higher organic matter and microbial activity), increased agronomic N use efficiency, improved fruit quality attributes and produced greater marketable yield and economic return. This study evaluated the effects of combined mineral nitrogen (N) and vermicompost (VC) fertilization on the growth, yield, fruit quality, and economic performance of three tomato varieties (GALILEA 39, NUN TOP, and ALBATROS) at Shallo Farm during the 2016 E.C. cropping season. Treatments consisted of three nitrogen rates (0, 175, and 350 kg N ha⁻¹) and three vermicompost levels (0, 5, and 7 t ha⁻¹) arranged in a randomized complete block design with three replications. Data were collected on phenology, growth, yield, and fruit quality parameters, while economic feasibility was assessed using partial budget analysis. The collected data were analyzed using ANOVA under the GLM procedure in SAS 9.4, and assumptions were verified by checking normality and variance homogeneity through diagnostic plots; percentage variables were normalized using the arcsine square-root transformation. Results revealed that variety, nitrogen, and vermicompost rates, as well as their interactions, significantly influenced most growth, yield, and quality traits. GALILEA 39 recorded the highest fruit set (78.26%) and total yield (14.02 t ha⁻¹) under 350 kg N ha⁻¹ + 5 t VC ha⁻¹. Nitrogen enhanced vegetative growth and fruit size, while vermicompost improved soil fertility, flower retention, and fruit development. Physical fruit quality improved with N and VC increased fruit length and fruit shape index, vermicompost increased fruit width, and the N × VC interaction produced the thickest pericarps, indicating greater firmness and better postharvest life . Chemical quality responded positively to integrated fertilization: moderate to high N rates and both VC levels raised TSS and SAR, whereas TA increased relative to the unfertilized control but plateaued beyond 175 kg N ha⁻¹, producing a net improvement in taste and processing quality. Partial budget analysis showed that the combination of 175 kg N ha⁻¹ and 7 t ha⁻¹ vermicompost generated the highest net field benefit (476,937.36 Birr) and marginal rate of return (2521.48%) for GALILEA 39, while NUN TOP achieved the greatest profitability (MRR = 5621.85%) under the same combination. For ALBATROS, 350 kg N ha⁻¹ with 5 t VC ha⁻¹ was most economical (MRR = 5210.50%). Therefore, under the agro-ecological conditions of Bishan Guracha, applying 175 kg N ha⁻¹ with 7 t ha⁻¹ vermicompost is recommended for GALILEA 39 and NUN TOP, while 350 kg N ha⁻¹ with 5 t ha⁻¹ vermicompost is optimal for ALBATROS. . Future studies should refine nitrogen–vermicompost ratios across soil types and assess long-term effects on soil health, productivity, and sustainability.