Geochemical characteristics of soils and representative tea gardens in the Yangxi-Tongle area, Sanjiang, Guangxi Zhuang Autonomous Region

This study aims to gain insights into soil pH, the degree of abundance of beneficial nutritional elements in soils, and the characteristics of element migration and accumulation within the rhizosphere soil-tea leaf system in the Yangxi-Tongle area of Sanjiang Dong Autonomous County, Guangxi Province. This study conducted a statistical analysis of 881 sets of geochemical data from topsoil in agricultural land and 14 sets of data from the tea leaf - rhizosphere soil system across 315 km² in the study area. The analytical results indicate that topsoil in the study area is acidic to strongly acidic, while the rhizosphere soil of tea trees is strongly acidic. The soils exhibit strong heterogeneity of Mn, Se, and Mo, with soil elements demonstrating distinct N-Corg-S and Cu-Mo-Se associations. The results also show that soils in the study possess fairly abundant to abundant total N, total K, organic matter, S, B, and Mo; fairly deficient to deficient total phosphorus, Ca, Mg, Fe, Mn, Cu, Zn, and F; and abundant Se. Tea leaves exhibit relatively strong capacity for bioaccumulation of Zn, Cu, Cd, B, Ni, and F in soils, but relatively weak capacity for bioaccumulation of As, Pb, Cr, and Ge. This study concludes that tea leaves in the study area contain moderate Se content; low contents of Cd, As, and Hg; and a Pb content within regulatory limits, suggesting generally safe tea quality. The results of this study further provide a geochemical basis for the healthy development of the local tea industry.