https://doi.org/10.37229/fsa.fjh.2026.05.18

This study was conducted during the spring season of 2025 in the vegetable field of the Department of Horticulture and Landscape Engineering / College of Agriculture and Forestry / University of Mosul. Planting was conducted on 1/27/2025, with the aim of studying the effect of vermicompost and biochar on the soil before planting and the interaction between them on the growth and yield of green onion (Allium cepa L.) crops. The experiment was carried out according to a randomized complete block design (R.C.B.D.) with a factorial experiment with two factors: vermicompost at four levels (0, 5, 7.5, 10 tons ha^-1) and biochar at three levels (0, 5, 7.5 tons ha^-1). They were statistically analyzed according to the design used and the means were compared according to Duncan’s multinomial test at the probability level of 0.05. The results showed that adding vermi compost led to an improvement in growth characteristics and yield, as the level (10 tons ha^-1) achieved the highest significant values in most of the vegetative growth characteristics (chlorophyll, plant height, and leaf area), as well as quantitative yield indicators such as the average weight of a single bulb without leaves, the percentage of dry matter in the bulbs, the percentage of double bulbs, and the average weight of a single bulb. The biological bulb, the quotient of the experimental unit area, the biological quotient of the total unit area, and the percentage of bulb (50.201 mg.g^-1, 69.265 cm, 405.160 cm², 38.833 g, 25.009%, 13.33%, 193.267 g, 3.862 kg, 58.515 tons ha^-1, 34.861%, respectively, superior to the rest of the addition levels and the comparison treatment. The results also showed a significant effect of adding biochar on all the studied traits, as the addition treatment at the level of (7.5 tons ha^-1) significantly exceeded the total chlorophyll content in the leaves, plant height, leaf area of the plant, average weight of one bulb without leaves, average biological bulb weight, biological yield per unit of experimental area, biological yield per unit of total area, percentage of dry matter in Bulbs, the percentage of double bulbs, and the percentage of bulbs compared to the treatment of no addition and addition to the level (5 tons ha^-1), (44.507 mg.g-1,65.471 cm2, 344.180 cm2, 38.369 gm, 165.667 gm, 3.313 kg, 50.204 tons ha^-1, 21.842%, 8.75%, and 30.914%, respectively. As for the binary interaction coefficients, they showed significant superiority when treating the interaction of adding (10 tons ha-1) of vermicompost with (7.5 tons ha^-1) of biochar in most of the studied traits, especially in plant height, leaf area, the average weight of a single bulb without leaves, the percentage of double bulbs, the biological weight of the bulb, and the biological yield per unit experimental area. The biological yield per unit area is the total area, as well as the percentage of follicles. (71.213 cm, 435.310 cm², 43.343 g, 18.33%, 212.533g, 4.251 kg, 64.409 tons ha^-1, 38.488%) compared to all other interference treatments and the comparison treatment that recorded the lowest values.