The study aimed to improve onion yield by testing different combinations of chemical fertilizers and compost. Red Azarshahr onion variety outperformed Qoli Qissa. Using a mix of chemical fertilizers and compost increased vegetative growth, bulb size, and overall yield compared to using compost alone. Combining ¾ of the recommended chemical fertilizer with 4 tons of compost, or using half the recommended fertilizer with 8 tons of compost, did not decrease bulb weight or yield. These combinations are recommended for the region to boost onion production.