The aim of this study was to determine effect of nitrogen and sulphur applications on mineral content of of onion`s leaf. The study was carried out in Atatürk Central Horticultural Research Institute in the years of 2012 and 2013 in Yalova. The fertilizer were applied in combination of N, S and rates of the N– S combinations were 0-50-100 -200 kg N ha-1 and 0-25-50-100 kg S ha-1. The effects of fertilizer applications on nitrogen, phosphorus, potassium, calcium, magnesium and sulphur content of leafs were determined in the study. Nitrogen content of leaf was significantly affected by applied nitrogen. Nitrogen content of leaf was increased by higher doses of nitrogen fertilization. There was no effect from sulphur fertilization. Both year, the highest nitrogen content were determined by 20 kg N da-1 dose. The nitrogen content of first and second year was 2.61-3.00% and 2.78-3.21% respectively. The relation between nitrogen fertilization and leaf`s phosphorus content were significant in the first year; but second year not. Additionally, the effect of nitrogen and sulphur fertilization on potassium, calcium, magnesium and sulphur content were statistically unsignificant. They were determined between 0.16- 0.19%, 0.19-0.21% for P; 3.60-4.12%, 3.46-3.94% for K; 2.85-3.35%, 2.99-3.41% for Ca; 0.34–0.44%, 0.36–0.39% for Mg and 0.53–0.79%, 0.66–0.69% for S at 2012 and 2013 respectively.
