Chicken manure and spacing effects on onion yield and quality at Bonga, Ethiopia

Onion ( Allium cepa L.) is a vital bulb crop cultivated globally. Effective agronomic practices, including optimal use of organic fertilizers and appropriate plant spacing, significantly enhance crop yields. Therefore, this research was conducted to investigate the effect of chicken manure rates and intra-row spacing on the growth, yield, and yield quality components of onion ( Allium cepa L.) at Bonga University, South Western Ethiopia, in 2025. The experiment consisted of three intra-row spacing levels (8, 10, and 12 cm) and four chicken manure levels (0, 2.5, 5.0, and 7.5 t ha⁻¹) in factorial combinations arranged in a Randomized Complete Block Design (RCBD) with three replications. The results showed that growth parameters, bulb yield, and quality of onion were significantly influenced by chicken manure rate and intra-row spacing. The interaction effect of the two factors had a significant effect on days to maturity, plant height, leaf width, bulb diameter, bulb weight, neck thickness, marketable yield, total yield, fresh biomass, and harvest index. Under the conditions of this experiment, the highest marketable yield (15.90 t ha⁻¹) and total yield (17.40 t ha⁻¹) were recorded from the combination of 7.5 t ha⁻¹ chicken manure with 12 cm intra-row spacing. Therefore, in the study area, farmers are recommended to use 7.5 t ha⁻¹ chicken manure with 12 cm intra-row spacing for maximum yield, or 5 t ha⁻¹ with 10 cm spacing as an alternative.