The effects of different levels of biochar and humic acid on the growth parameters, photosynthetic pigments, and nutritional content of blue fescue were investigated. The experimental design of this study was a factorial experiment based on a completely randomized design with three replications. The results showed that the interaction between humic acid and biochar had a significant effect on shoot length, shoot dry biomass, root- to-shoot (R/S) biomass ratio, total chlorophyll, chlorophyll a, chlorophyll b, carotenoids, and leaf concentrations of N, P, K, Ca, Mn, Fe, Zn, and Cu. Root dry biomass was affected by humic acid and increased at 200 mg L⁻¹ and 400 mg L⁻¹ humic acid compared to the control. Increasing the application rates of biochar and humic acid resulted in an increase in leaf nutrient contents in blue fescue. The highest levels of chlorophyll a and chlorophyll b were recorded at 40 g kg⁻¹ biochar combined with 200 mg L⁻¹ humic acid and 40 g kg⁻¹ biochar combined with 400 mg L⁻¹ humic acid, respectively. The use of biochar and humic acid, especially at application rates of 40 g kg⁻¹ and 400 mg L⁻¹, respectively, significantly improved most of the traits evaluated in this experiment. When biochar and humic acid were applied together, their effects were more pronounced

Keywords