Enhancement of oil physicochemical properties and residual cake feed quality in camelina cultivars, through seeding and blended NPSB fertilizer rates in Hadiya zone central Ethiopia

This study examined the effects of seeding rates and NPSB (Nitrogen-Phosphorus-Sulfur-Boron) fertilization on the physicochemical properties of Camelina sativa oil and the nutritional quality of its residual cake in Ethiopia's Hadiya zone. A split-split plot design was employed to test two cultivars (Zeytee-1 and Syria), three seeding rates (5, 7.5, and 10 kg ha −1 ), and four NPSB levels (0, 50, 100, and 150 kg ha −1 ). From each treatment, 200 g of seed was sampled for oil extraction and analysis standard. Oil traits measured included acidity, density, peroxide value, volatile matter, refractive index, iodine value, and saponification value. Residual cake was analyzed for crude fat, protein, acid detergent fiber (ADF), neutral detergent fiber (NDF), and ash content. Results indicated that higher NPSB rates (150 kg ha −1 ) significantly reduced peroxide values, enhancing oil stability. Cultivar-fertilizer interactions influenced oil content and quality traits, with Zeytee-1 recording the highest oil content (39.8 %) at 100 kg NPSB ha −1 . Residual cake composition improved with increased NPSB and seeding rates, particularly protein and fiber levels. Syria at 10 kg ha −1 with 150 kg NPSB ha −1 produced the highest cake yield and protein content. Partial budget analysis identified this treatment as most profitable. Overall, integrated nutrient and seeding management enhanced oil quality, co-product value, and economic returns for smallholder farmers. • NPSB fertilizer rates improved Camelina oil stability by reducing peroxide values. • Zeytee-1 reached 39.8 % oil content with 100 kg NPSB ha −1 . • Syria cultivar gave highest cake yield and protein at 150 kg NPSB ha −1 . • Seeding and NPSB rates boosted crude protein and fiber in residual cake. • Economic analysis confirmed Syria × 150 kg NPSB as most profitable.