Growth and yield of onion (Allium cepa L.) as affected by farmyard manure and nitrogen fertilizer application in Tahtay Koraro District, Northwestern Zone of Tigray, Ethiopia

A field experiment was carried out in Tahtay Koraro district of Northwestern zone of Tigray from October 2017 to April 2018, to assess the effect of organic and inorganic fertilizer on growth, yield and yield components of onion. The experiment consisted of four levels of FYM (Farmyard manure) as 0, 10, 20 and 30 t ha−1 and four levels of inorganic N as 0, 34.5, 69 and 103.5 kg ha−1 factorially arranged in RCB design with three replications. Analysis of variance revealed that the main effect of N, FYM as well as their interactions significantly (P < 0.05) influenced days to maturity, plant height, leaf number, leaf diameter, bulb diameter, neck diameter, average bulb weight, above ground dry biomass, marketable bulb yield and total bulb yield of onion. Similarly, main effects of N and FYM significantly (P < 0.05) affected leaf length, bulb length, unmarketable bulb yield and harvest index. The highest marketable bulb yield of 35.93 t ha−1 and 34.72 t ha−1 were obtained at combinations of 103.5 kg N ha−1 + 30 t FYM ha−1 and 103.5 kg N ha−1 + 20 t FYM ha−1 respectively. However, the lowest marketable bulb yield of 13.88 t ha−1 was obtained from the unfertilized plot. Moreover, the highest marginal rate of return was obtained at combined application of 103.5 kg N ha−1 and 10 t FYM ha−1 and thus can be recommended for onion production in the study area. © 2020, The Author(s).