A field experiment ensued during the winter crop season 2018–2019 at the District Baqubah, Diyala Governorate, Iraq, to study the effects of three plant spacing (20, 40, and 60 cm) and foliar application of humic acid with four concentrations (0, 10, 20, and 40 L ha^-1) on seed yield-related traits and active ingredients of goat pea (Securigera securidaca L.). The recorded data underwent statistical analysis using a randomized complete block design (RCBD) with factorial arrangement. The results showed that the plant spacing of 60 cm was superior in the percentage of oil and the total content of glycosides in the seeds, amounting to 3.84% and 27.86 mg g^-1, respectively, and the plant distance of 40 cm was superior in the seeds’ total phenol content (1.23 mg g^-1). As for 20 cm, it was excellent in the oil yield (15.56 kg ha^-1). The spraying with humic acid at the rate of 20 L ha^-1 provided the highest percentage and harvest of oil and total phenol content, reaching 3.69%, 9.30 kg ha^-1, and 1.21 mg g^-1, respectively. The interaction between the plant distance (60 cm) and foliar application of humic acid (10 L ha^-1) showed a significant increase in the percentage of oil, amounting to 3.92%. The interaction between the plant distance (40 cm) and foliar application of humic acid (20 L ha^-1) provided a substantial increase in the total phenol content of seeds (1.25 mg g^-1).

Keywords: goat pea (Securigera securidaca L.), plants distances, humic acid, oil percentage, yield, phenols, glycosides

Key findings: Increased plants distance to 60 cm led to an increase in the percentage of oil content. Foliar application of humic acid (20 L ha^-1) gave a significant superiority in seed yield in the plant, oil content ratio and harvest, and total phenol content.