Effect of nitrogen and phosphorus fertilizer rates on growth and yield of hybrid onion (Allium cepa L.) in semi-arid Northern Ethiopia

Abstract

Onion (Allium cepa L.) is an important crop with high nutritional and medicinal value and provides income for smallholder and large-scale farmers. Utilizing blanket fertilizer recommendations for open-pollinated onion varieties often results in suboptimal productivity. Therefore, it is crucial to optimize fertilizer requirements for high-yielding onion hybrids to enhance onion production. This study assessed the effects of nitrogen and phosphorus fertilizers on the growth and yield of onion hybrid Neptune in Woleh during the dry- winter season of 2024. The analysis of variance indicated that nitrogen and phosphorus fertilizers significantly affected (P ≤ 0.05) onion growth and yield. The treatment combinations of 138 kg N ha− 1 and 34.5 kg P2O5 ha− 1 recorded the highest marketable bulb yield of 32.77 t ha− 1 and the highest net benefit with acceptable marginal rate of return (MRR) (4546.64%). Accordingly, application of 138 kg N ha− 1 and 34.5 kg P2O5 ha− 1 is recommended for the production of onion hybrid Neptune in Woleh. Since, the experiment was conducted in one location and for one season, further studies across different areas and multiple growing seasons are recommended to establish reliable and broadly applicable nitrogen and phosphorus fertilizer recommendations for onion.