Accepted 6th April, 2017
Field trials were conducted during 2012 and 2013 cropping seasons to determine the interaction of nitrogen and potassium containing fertilizers on the yield and mineral compositions of onion. The treatments were three nitrogen (N) levels (45, 60 and 75 in kgha-1) and four potassium (K) levels (60, 90, 120 and 150 in kgha-1) from urea and muriate of potash (MOP) respectively. The treatments were laid out in a randomized complete block design replicated three times. Data collected were yield attributes and nutritional values of onion. Data were analyzed using analysis of variance and treatment means compared with least significant difference at 5% probability level. Interaction of N and K fertilizers significantly (p<0.05) increased the yield parameters with the optimum values obtained at 60 kg Nha-1 x 120 kg K2Oha-1 in 2012 and 2013, respectively. The highest mean marketable yield of 2.6 tons ha-1 was obtained with combined application of 60 kg Nha-1 by 120 kg K2Oha-1 in both years. The best mineral compositions (N, P, K, Ca and Mg,) were obtained from plant treated with combined application of 60 kg N ha-1 and 120 kg K2O ha-1.
In conclusion, combinations of 60 kg Nha-1 and 120 kg K2Oha-1 produced the optimum marketable yield and mineral compositions of onion in the study area.
Keywords: Nitrogen, potassium fertilizer, onion, yield and smineral compositions