Humic acid comprises the major part of humic substances and the most important component of soil organic matter (humus) that increases crop yield and quality. This research aimed to investigate the effects of amount and time of humic acid (HA) application on quantitative (plant height, seed yield, biologic yield and harvest index) and qualitative traits (seed protein yield, moisture, and nutrients) of faba bean. The plant was cultivated in a research field (Chalus, Iran) during 2014–15. There were HA treatments at four levels (control, 200, 300, and 400 mg L⁻¹) and three spraying times (before planting, mid-vegetative growth, and early reproductive growth). Results showed that plant height, harvest index, and seed moisture and nutrients were influenced by HA treatments. Seed and protein yields were uppermost in 200 and 300 mg L⁻¹ of HA treatments, respectively, at mid-vegetative growth stage. The highest levels of seed moisture and nutrients were obtained with 300 mg L⁻¹ of HA application at mid-vegetative growth stage in the second year. Increasing HA levels led to improvements in all the examined traits, except the harvest index. According to the results, HA foliar application of 300 mg L⁻¹ is recommended at mid-vegetative growth stage to achieve optimum seed yield.

腐植酸是腐殖质的主要成分，也是提高作物产量和品质的土壤有机质（腐殖质）中最重要的成分。本研究旨在研究腐植酸（HA）的施用量和时间对蚕豆数量性状（株高、种子产量、生物产量和收获指数）和质量性状（种子蛋白质产量、水分和营养成分）的影响。该植物于 2014-15 年在研究领域（伊朗查卢斯）种植。有四个水平的 HA 处理（对照、200、300 和 400 mg L ^-1) 和 3 次喷洒（种植前、营养生长中期和生殖生长早期）。结果表明，株高、收获指数、种子水分和养分受HA处理的影响。在营养生长中期，种子和蛋白质产量分别在 200 和 300 mg L ^-1 HA 处理中最高。在第二年的营养生长中期，施用300 mg L ^-1 HA可获得最高水平的种子水分和养分。提高 HA 水平导致所有检查性状的改善，收获指数除外。根据结果​​，建议在营养生长中期叶面喷施 300 mg L ^-1 HA以达到最佳种子产量。