The study looked at how different types and amounts of fertilizer affect the growth and yield of onion plants. They tested NPK 15:15:15 inorganic fertilizer and poultry manure in two field experiments. The results showed that using 80 kg/ha of NPK 15:15:15 with 15t/ha of poultry manure produced the highest onion yield. This combination improved crop growth rate, chlorophyll content, harvest index, and individual bulb weight. In the 2011/2012 season, the yield was 29.55 t/ha, and in the 2012/2013 season, it was 28.17 t/ha. Additionally, using 120 kg/ha of NPK 15:15:15 with 15 t/ha of poultry manure resulted in the highest shoot yield of 7.06 t/ha in 2011/2012 and 6.89 t/ha in 2012/2013.