Keywords: Onion growth, Bulb yield, Nutrient uptake, Nutrient use efficiency, Economic analysis
Field experiment was conducted in Northern Ethiopia during 2016–2017 to evaluate the agronomic and economic performance and nutrient use efficiency of onion under N, K and S nutrient combination levels. Three levels of N (0, 69, 92 kg ha−1), three levels of K (0, 45, 67 kg ha−1), and two levels of S (0 and 15 kg ha−1) were laid out in a randomized complete block design with three replications. Combination of N, K and S nutrient levels appreciably resulted significant variation on growth and bulb yield components, nutrient use efficiency and nutrient uptake, and on the economic performance of the treatments. Statistically higher plant height and leaf area was recorded when onion was cultivated under N92S15K67. Whereas, maximum number of leaf was observed from N92S15K45. Regardless of the K level, lower growth performance of onion was recorded from treatments allotted to zero N and S levels. The combination of 92 kg/ha N and 15 kg/ha S improved productivity of onion, regardless K fertilization. Likewise, higher bulb diameter, fresh bulb weight and dry weight were observed from N92S15K67 treated plots. The different nutrient combinations have influenced not only growth and yield of onion but also the nutrient use efficiency. N, K and S nutrient combinations significantly improved agronomic efficiency, partial factor productivity and apparent nutrient recovery. The economic analysis of the present study depicted that experimental plots which received N69S15K0 nutrient combinations have recorded higher marginal rate of returns.