Impact of Liming and Deficit Irrigation on Sunflower Yield and Uptake of Selected Nutrients in Acidic Soils (Trakya Region)

This study evaluated the combined effects of liming and deficit irrigation on sunflower yield, leaf nutrient concentrations (nitrogen, phosphorus, and zinc), and soil pH in acidic soils of the Thrace Region, Türkiye, where soil acidity and water scarcity are major constraints to crop production. A two-year field experiment was conducted using a factorial randomized block design with three liming rates (0, 6, and 12 t CaCO₃ ha⁻¹) and three irrigation regimes (rainfed, 50%, and full irrigation at critical growth stages). Liming significantly increased sunflower yield in both years (p < 0.05), with the highest yield obtained under the combined application of 6 t ha⁻¹ lime and full irrigation, reaching 4.40 and 3.76 t ha⁻¹ in the first and second years, respectively, corresponding to an increase of up to 55% compared to the control. Soil pH increased markedly following liming, while irrigation enhanced the downward movement of liming effects within the soil profile. Leaf nitrogen (N), phosphorus (P), and zinc (Zn) concentrations were not significantly affected by treatments; however, slight increasing trends were observed under liming and irrigation, suggesting a potential improvement in plant nutrient status rather than a direct increase in nutrient uptake. Overall, moderate liming combined with appropriate irrigation represents an effective strategy for improving sunflower productivity in acidic soils; however, the limited response in nutrient concentrations indicates that additional nutrient management practices may be required.