Improving onion productivity through optimum and economical use of soil macronutrients in Central Rift Valley of Ethiopia

Abstract

Various constraints are reported for the low productivity of onion in Ethiopia and among which inappropriate and uneconomical uses of soil macronutrient are the most important ones. This study is, therefore, undertaken to improve the productivity of onion through optimum and economical use of soil macronutrient (N and blended NPS) in the Central Rift Valley of Ethiopia under supplemental irrigation. The experiment was arranged in a factorial combination of four N (0, 46, 92 and 138 kg ha-1) and four NPS (0, 121, 242 and 363 kg ha-1) fertilizer levels in randomized complete block design with three replications. Data on phenology, growth, and yield and quality components of onions were recorded. The main effects of N and NPS fertilizer levels had significantly influenced days to 70% maturity, plant height, leaf length, bulb diameter, bulb length, average bulb weight, bulb dry weight, total biomass yield and total soluble solids. The interaction effect also significantly affected leaf number, total bulb yield and marketable bulb yield of onion. The highest total and marketable bulb yields of 47.69 and 47.42 t ha-1, respectively, were obtained from 92 kg ha-1 N combined with 242 kg ha-1 of NPS fertilizer. Therefore, it can be concluded that 92 kg ha-1 of N and 242 kg ha-1 of NPS blended fertilizer with having 46 nitrogen, 92 phosphorus and 16.94 sulfur is economically feasible to improve the productivity of onion in the study area and similar environment. As the experiment was done for one variety, season and location, it has to be repeated with other varieties over seasons and locations to make a conclusive recommendation.