Enhancing bread wheat yield and growth in new sand soils via potassium humate supplementation and copper foliar spray

Abstract Wheat is the main cereal crop and staple food worldwide. A field study was carried out at Ismailia Agricultural Research Station in Egypt using sprinkler irrigation during the two successive seasons of 2024/2025 and 2025/2026 to examine the impact of potassium humate supplementation and/or copper foliar spraying on enhancing morpho-physiological parameters, nutritional content, yield and yield components in newly sand soils. A split-plot design with three replicates was carried out, with foliar sprays of Cu in subplots and potassium humate in main plots. The Giza 171 wheat cultivar was treated with potassium humate (0 and 30%), and wheat plants were sprayed with varying concentrations of copper (0, 10, and 20 mg/L). The acquired data confirmed that the exogenous potassium humate application at 30% seems to enhance all growth metrics, membrane stability and photosynthetic pigments as well as improving leaf turgidity by raising relative water content, lowering saturation deficit, which in turn increased yield and yield components during both seasons. Moreover, a gradual rise in copper up to a high level of 20 mg/L enhanced morpho-physiological parameters, consequently inducing wheat grain yield. Furthermore, all levels of copper, especially 20 mg/L, improved yield characteristics, grain output, and the grain nutritional content (the percentage of NPK and total protein in wheat grains). Thus, this study showed that foliar copper application specifically, at 20 mg/L proved to be an effective strategy for increasing grain yield. When potassium humate and foliar copper application were combined, the greatest increase in grain yield was observed with 30% potassium humate and Cu20 mg/L, recording 889.67 and 900.34 g/m 2 for the first and second seasons, respectively. We came to the conclusion that potassium humate supplementation at 30%, and copper foliar spray up to 20 mg/L are certain to boost wheat production cultivated on newly sand soils.