Growth and Yield of Onion (<i>Allium cepa</i> L.) as Affected by Variable Rates of Poultry Manure and Mineral Nitrogen Fertilizer at Alage, Central Rift Valley Ethiopia

Abstract

Onion is one of the important vegetable crops produced in many home gardens and in some extent commercially in different parts of Ethiopia. Therefore, this experiment was conducted at Alage Central Rift Valley of Ethiopia with the objectives of assessing the growth, yield, and quality response of onion to the variable rates of poultry manure and mineral nitrogen fertilizer. The experiment comprising of three nitrogen levels (0, 46, and 92 kg ha<sup>-1</sup>) and four levels of poultry manure (0, 5, 10, and 15 t ha<sup>-1</sup>) were laid out in a randomized complete block design with three replications. The result indicated that leaf length, leaf number, days to maturity, bulb length, and bulb dry matter content were significantly influenced by main factors. Application of poultry manure at the rate of 15 t ha<sup>-1</sup> recorded the highest total bulb yield (63.33 t ha<sup>-1</sup>) and marketable bulb yield (62.52 t ha<sup>-1</sup>), but statistically, there was no significant difference between 15t ha<sup>-1</sup> and 10t ha<sup>-1</sup> poultry manure application. The results of the partial budget analysis showed that 15 t ha<sup>-1</sup> poultry manure application gave the highest marginal rate of returns. Since the highest bulb yield and maximum marginal rate of returns are obtained at 15 t ha<sup>-1</sup> poultry manure application, this rate can be recommended for onion production in the researched area, and areas having similar agro-ecologies. However, as the research is conducted for a single season and location, repeating the experiment over location and year will be required to give a conclusive recommendation.