Soil nutrient status in tea gardens on the Yunnan-Guizhou Plateau and their effects on tea quality

In order to reveal the relationship between soil environmental factors and tea quality in tea gardens on the Yunnan-Guizhou Plateau and to provide the theoretical basis for tea quality optimization more scientifically, 52 soil samples and corresponding tea samples were collected from three major tea-producing areas in Guizhou Province to determine the nutrient and trace element contents in the soil and tea quality parameters in June 2022. The results showed that the range of Fe, Cu, Zn, Mn, and Mo contents of tea plantation soils in Guizhou Province were 82.67-135.80, 0.53-1.68, 2.94-5.60, 16.26-97.80, and 0.03-0.07 mg/kg, respectively, which were rich in trace elements and able to provide a rich source of trace elements for the tea tree. Soil organic matter content and pH were 49.59~68.64 g/kg and 4.45~4.70, respectively, which could provide a good growing environment for tea trees. As a typical Mn-enriched plant, tea in Guizhou Province had the highest Mn enrichment coefficient, the lowest Mo and Fe enrichment coefficients, and Zn and Cu varied in different planting areas. Results based on the random forest model showed that Zn, TP and TN in tea garden soil had the greatest influence on free amino acid content in tea, TN, pH and TP had the greatest influence on polyphenol content, pH, TK and TN had the greatest influence on caffeine content, and TK, Mn and Fe had the greatest influence on water leachate content of tea. The study showed that soil nutrient contents had a greater influence on tea quality, while trace elements had a lesser effect on tea quality.