Effects of Humic Acid and Nitrogen Levels on Growth, Yield, and Nutrient Uptake of Flax (Linum usitatissimum L.) in Calcareous Soil

Flax is one of the earliest plants that humans have domesticated. Due to its high omega-3 and fatty acid content, its cultivation and consumption have increased as a healthy oil resource. It was tested in the fields of Qaladza city, Sulaimani governorate, Iraq, during the growing season of 2022–2023. Four different amounts of humic acid (0, 50, 100, and 150 kgHA ha-1) and four different amounts of nitrogen fertilizer (0, 100, 200, and 300 kg N ha-1) were used to see how they affected the flax variety Thorshansity 72, which is a cultivar from Poland. Results indicated that from a nutritional point of view, humic acid and nitrogen are two critical elements in plant growth. There were significant differences in the plant height, number of fruiting branches, and number of capsules per plant based on the humic acid and nitrogen fertilizer rates. Differences were also observed in the number of seeds per capsule and seed yield. There were also differences in the nutrients found in the soil, shoots, and roots, and the amount of oil in the seeds of a flax plant.