EFFECT OF COMBINED APPLICATION OF VERMICOMPOST AND INORGANIC NPS FERTILIZERS ON YIELD RELATED TRAITS, YIELD AND SHELF LIFE OF SHALLOT [Allium cepa var. Ascalonicum Backer]AT HARAMAYA, EASTERN

The productivity of shallot is low due to low soil fertility as one of many constraints. Thus this research was conducted to assess the effects of combined application of vermicompost (VC) and inorganic NPS fertilizer on bulb yield, yieldrelated traits, shelf life of shallot, soil physical and chemical properties for sustainable nutrient management without harming the environment. The field experiment consisted of four rates of NPS (0, 50, 100 and 150 kg NPS ha-1) and five VC rates (0, 2.5, 5, 7.5 and 10 t VC ha-1) laid out in a randomized complete block design with three replications and carried out in 2018/2019. Results of analysis of variances revealed that the rates of NPS and VC and their interaction significantly influenced allbulb yields and yield related traits of shallot except all factors on neck thickness of bulb(cm), interaction of NPS and VCon days to maturityand bulb length(cm) as well as NPS fertilizer on bulb lengthhad nonsignificanteffect. The two fertilizers and their interaction had significant effect on all selected physical and chemical properties of soil after harvesting of shallotexcept pH of the soil. The NPS and VC and the interaction of the two factors also significantly influenced bulb weight loss starting 30 to 90 days storage, rotten bulb and sprouting bulb of shallot except bulb weightloss at 15 days of storage and NPS x VC interaction on sprouting of bulb at 60, 75 and 90 days storage after harvest. Analysis of variances revealed that the highest plant height (72.1cm), leaf length (64.65cm), leaf number per plant (16.59), marketable bulb yield (70.49) and total bulb yield (72.92 t ha-1) were observed from the interaction of 100 kg NPS ha-1 with 5 t VC ha-1 . The widest bulb diameter (8.067cm) and highest mean bulb weight (135.2g) were registered from the interaction of 100 kg NPS ha-1 and 10 t VC ha-1 and highest bulb dry matter (13.430%) were produced from combined application of 100kg NPS ha-1 with 7.5 t VC ha-1. The interaction uses of 100-150 kg NPS ha-1with 5-10 t VC ha-1 increased significantly than control treatment for organic carbon, total nitrogen, available K, available P, Cation exchange capacity, and water holding capacity of the soil. The highest physiological weight loss (31.89%) was observed at the combined application of 150 kg NPS fertilizer ha-1 and 10 ton VC ha-1 during 90th day storage period. While lowest weight loss was recorded from the combined application of 100 kg NPS ha-1 and 5 t VC ha-1 .The highest percentage bulb sprouting was recorded for plants fertilized with 150 kg NPS ha1 and 100 kg NPS ha-1 at 60th day after storage. The highest percent of rotten bulbs were observed under combined application of 150 kg NPS ha-1 and 10 t VC ha-160thday from storage period. In contrast the interaction of 100 kg NPS ha-1 with 5 t VC ha-1 resulted in lowest bulb rotting next to unfertilized plots at 60th day storage period. The highest marginal rate of return (MRR%) of 25632% was estimated for plots that received 100 kg ha-1 NPS fertilizer, but the highest adjusted marketable bulb yield of 63.441 t ha-1 with the highest net benefit and benefit to cost ratio of 1,469,548 Birr ha-1 and 4.79, Birr ha-1 respectively, were estimated for plots that supplied 100 kg ha-1NPS fertilizer in combination of 5 t ha-1vermicompost. The MRR (%) of 2186.48% was estimated for this treatment, thus the tentative recommendation was made in favor of the application of 100 kg ha-1NPS fertilizer in combination of 5 t ha-1vermicompost for shallot production at Haramaya.