Humic acid that improves plant growth and yield indices such as fresh and dry weights, plant height. Field experiment was conducted at the Al-Mussaib Technical Institute/Iraq during the 2022-2023 season to study the effect of adding NPK complex fertilizer to the soil and spraying with organic fertilizer (Humic acid) on the growth and yield of black mustard plants, according to a randomized complete block design (RCBD) with three replications. In this study, the effect of foliar application of Humic acid and/or fertilizers of NPK on the growth characteristics of black mustard (Brassica nigar) in field conditions were compared. According to the results, the foliar application of Humic acid The results were analyzed according to analysis of variance, and the means were compared using the least significant difference (LSD) test under the probability level of 0.05.A two-factor experiment (3×3) was carried out. The first factor was the addition of a balanced NPK complex fertilizer (20:20:20). At levels of (0, 30, or 60) kg/dunum in two batches, the first two weeks after germination, and the second when flowering begins. The fertilizer was placed about 10 cm under the plant in the furrows and covered with dirt, then watered after fertilization. The second factor was spraying with three concentrations of organic fertilizer (Humic acid) (0, 2, or 4) ml.l-1. It was observed from the results that adding NPK complex fertilizer and organic fertilizer (Humic acid) has a significant effect on the characteristics of vegetative growth, as is evident from the fact that the levels of NPK complex fertilizer and spraying with organic fertilizer (Humic acid) have a significant effect on the productive characteristics of the plant. It is conclude from this experiment that the most effective treatment that can be used to feed the black mustard plant under the conditions of this experiment, and which achieved the best results in improving the vegetative and productive characteristics of the plant, is the 60 kg overlap treatment. 1 dunam-1 NPK with spraying three times with 2 ml.l-1 of organic fertilizer (Humic acid), which improved the characteristics of vegetative growth and gave the highest rate of mustard number. Plant-1 and number of seeds. Mustard-1 and seed weight. Plant-1 and the amount of seed yield per dunum. application of 45 ppm humic acid with 60/kg – per dunum (per 2500 square meters) would be the best option to maintain better growth, yield and quality in black mustard.
