Study on Soil Acidification and Contents of Rare Earth Elements and Aluminum in Soil-Tea System of Typical Tea Gardens in Fujian

In order to explore the soil acidification and the changes of aluminum (Al) and rare earth elements (REEs) contents in the soil-tea system of tea gardens in Fujian Province, the typical tea areas of Anxi (38), Jian’ou (12) and Shouning (10) in Fujian were taken as the research objects. The samples of tea garden soil (tea planting soil), soil without tea planting near the tea garden (natural soil), as well as old leaves, mature leaves and tender leaves of tea were collected according to the years of tea planting, and the physical and chemical properties of soil and the contents of Al and REEs in the samples were analyzed. The results showed that: the content of available phosphorus and available potassium in the tea planting soil of typical tea plantation in Fujian was significantly higher than that in natural soil, but the pH decreased significantly. Among them, the proportion of tea planting soil samples with pH lower than 4.5 was as high as 87.50%. With the increase of tea planting years, the acidification of tea planting soil increased, and the content of exchangeable Al also increased significantly, while the content of exchangeable calcium and magnesium decreased significantly. The average content of total REEs in typical tea garden soils in Fujian was 247.632 mg·kg⁻¹, which was higher than the average level of soil in the world and China. Among them, the contents of cerium (Ce) and lanthanum (La) accounted for 62% of the total REEs content. The total REEs content in soil was significantly positively correlated with pH and significantly negatively correlated with soil alkaline hydrolyzable nitrogen contents. In tea leaves, the Al content increased significantly with the increase of leaf age. The Al content in old leaves was 15.3～28.5 times higher than that in tender leaves. The Al content in old leaves, mature leaves and tender leaves of Anxi tea garden was higher than that in Jian’ou and Shouning tea gardens. The absorption of total REEs by tea was mainly dominated by light REEs, which accounted for more than 70% of the total REE content. The total REEs content in old leaves was 10～15 times higher than that in young leaves. The total REEs content in Shouning and Anxi tea leaves was significantly higher than that in Jian’ou tea leaves, and the light REEs content in Shouning tea leaves was also significantly higher than that in Jian’ou tea leaves. This study revealed the relationship between soil acidification and Al accumulation in Fujian tea gardens, as well as the enrichment characteristics of Al and REEs in tea leaves, providing a scientific basis for the soil management and tea quality and safety in tea gardens.