Overview and trends of international research on soil acidification in tea plantations

Acidification of tea garden soils has emerged as a global concern, posing a significant challenge to the sustainable development of the tea industry. This study analyzed 118 relevant publications retrieved from the Web of Science (WoS) core collection database spanning 2000 to 2023 to comprehensively trace the evolution of research on this topic and grasp its core areas and frontier trends. The results indicates that there has been a notable surge in international research on soil acidification in tea gardens since 2018. China has the highest number of publications and the greatest influence, with all five top global research teams regarding publication output in this field originating from China. Research in this domain has primarily focused on the multifaceted impacts of soil acidification on tea garden ecosystems, encompassing alterations in soil physicochemical properties, disruptions to carbon, nitrogen, and phosphorus cycling, modifications to soil microbial ecosystems, and consequences for tea yield and quality. Additionally, studies have focused on soil aluminum toxicity, tea plant aluminum-tolerance mechanisms, and strategies for ameliorating soil acidification in tea gardens. Specifically, soil acidification undermines the stability of soil aggregates, diminishes the buffering capacity, and exacerbates soil compaction, thereby reducing the soil water-holding capacity and hindering root growth. This, in turn, leads to substantial leaching of base cations, decreasing base saturation and nutrient availability, fostering the mobilization and dissolution of aluminum, and increasing the risk of heavy metal (e.g., Cd, Pb, and Cr) accumulation in the tea leaves. Moreover, soil acidification accelerates the loss of soil carbon, nitrogen, and phosphorus, reduces soil microbial diversity, inhibits the growth of certain beneficial microorganisms (such as Pseudomonas adaceae and Bradyrhizobium), and impairs microbial activity, thereby adversely affecting the normal growth and development of tea plants as well as the yield and quality of tea leaves. Therefore, it is necessary to implement targeted measures to prevent and control soil acidification in tea gardens, depending on the degree of acidity. For example, applying organic fertilizers and biochar can effectively alleviate soil acidity and enhance fertility. Furthermore, the biogeochemical cycle of aluminum serves as a focal point of research in this field, whereas the persistent influence of soil acidification on nitrogen and phosphorus cycles in tea plantation systems remains a heated and cutting-edge topic. In summary, this study provides a comprehensive and insightful overview of the current state of international research on tea garden soil acidification along with its advancements. This study imparts invaluable perspectives tailored for researchers, policymakers, and practitioners alike by meticulously synthesizing pivotal findings and pinpointing emerging trends, thereby catalyzing the formulation of effective soil amelioration strategies and fostering the sustainable growth of the global tea industry.