At the Experimental Farm of El-Gemmeiza, Agric Res. Station, (ARC), Gharbya Governorate (Middle Delta, Egypt), two field experiments were conducted in the winters of 2020/2021 and 2021/2022 to examine the effects of nitrogen fertilization at 50, 75 and 100% of the recommended rate (equal 60, 90 and 120 kg N/fed., respectively) and treated soil with some soil conditioner (humic acid at 10 kg/fad., biochar at 5m³/fed. and humic at 10 kg/fad. + biochar at 5 m³/fad.), beside untreated soil (control) on plant growth , mineral uptake , yield and bulb quality of garlic cv. Sids 40 using a flow irrigation system in clay soil. Fertilizing garlic plants with 100% equal 120 kg N/fed. and treating soil with a mixture of humic acid at 10 kg /fed. and biochar at 5 m3/fed. had a significant effect on plant growth (plant height, number of leaves per plant, both neck and bulb diameter, as well as the fresh and dry weight of the bulb and leaves and the total fresh and dry weight), nitrogen, phosphorus, and potassium percentages, and its uptake by the leaves of garlic plants at 135 days from sowing, and gave the highest values of yield and its components (exportable, marketable yield, total yield/fed., and average bulb weight), as well as bulb quality (N, P, and K, total soluble solids, dry matter content, and pungency). Moreover, the interaction between nitrogen at a rate of 75% RR and the mixture of humic acid and biochar gave the best results for increasing the efficiency of nitrogen use, and the relative increases in the total yield were about (4.97 and 5.38%) compared to the interaction between nitrogen at a rate of 100% RR only in both seasons, respectively and a decrease in mineral nitrogen by 25%.