Optimizing sesame oil quality and profitability: Site‐specific nitrogen management with varieties for Central Ethiopian agroecology

Abstract

Sesame oil quality and nitrogen use efficiency are constrained by genotype, nitrogen availability, environment, and variety by N by site interactions. This study tested the hypotheses that higher N rates improve oil quality, that Tate outperforms Adi and Abasena, and that near‐neutral soils enhance oil stability. A factorial experiment (three varieties × five N rates) was conducted in randomized complete blocks with three replications at two contrasting sites (Sankura and Mito) in Central Ethiopia during 2024. Data on grain yield, oil content, physicochemical properties (acidity, peroxide, iodine, and saponification values), nitrogen use efficiency indices, residual cake nutrients, and economic returns were analyzed. Results showed that the cultivar Tate fertilized with 69 kg N ha ^{− 1} had the highest grain yield (945 kg ha ^{− 1} ) and oil content (52.3%). Higher N rates reduced peroxide value (from 4.45 to 3.76 meq O ₂ kg ^{− 1} ) and increased iodine (107.5 → 112.9 g I ₂ 100 g ^{− 1} ) and saponification values (187.1 → 189.7 mg KOH g ^{− 1} ). Mito exhibited superior oxidative stability. Agronomic efficiency at 23 kg N ha ^{− 1} (41.24 kg grain kg ^{− 1} N), declining at higher rates. Cake crude protein increased from 29.8% to 38.4% with N application. Partial budget analysis identified Tate fertilized with 46–69 kg N ha ^{− 1} as the most profitable. We conclude that site‐specific N management (46–69 kg ha ^{− 1} ) using variety Tate optimizes sesame oil quality, agronomic use efficiency (AUE), and profitability in Central Ethiopia. We recommend validating these findings across additional seasons and locations.