Integrated Assessment of Yield and Quality Performance of Tea (Camellia sinensis L.) Cultivated on Pseudopodzolic Gleyic Yellow Soils under Humid Subtropical Conditions

Abstract

This study presents an integrated assessment of soil fertility, tea yield, product quality, and economic efficiency under humid subtropical conditions on pseudopodzolic gleyic yellow soils of the Lankaran–Astara region, Azerbaijan. Field experiments were conducted during 2022–2024 on non-degraded and moderately degraded soils to evaluate the combined effects of mineral fertilizers (N180P120K90), organic compost (30 t ha⁻¹), and micronutrients (Zn and Mn) applied at different rates. Changes in agrophysical and agrochemical soil properties, green tea leaf yield, biochemical quality indicators (tannins and extractive substances), and economic performance were analysed. The results showed that soil degradation significantly reduced humus content, nutrient availability, porosity, and water–air regime, leading to lower productivity and quality. The combined application of macro- and micronutrients with compost substantially improved soil properties and increased tea yield and quality compared to unfertilised and mineral-only treatments. The highest yield (up to 4633 kg ha⁻¹), improved biochemical quality, and maximum economic profitability were obtained with combined Zn and Mn application under a balanced fertilization background. The findings demonstrate that sustainable tea production on pseudopodzolic gleyic yellow soils requires an integrated fertilization strategy that accounts for soil degradation level, nutrient balance, and agrophysical constraints. These results provide a scientific basis for environmentally sound and economically efficient tea management practices in humid subtropical regions.