Soil microbes are the key to revealing the mechanisms driving variation in soil biogeochemical processes. In recent decades, forests in Southeast China have been widely transformed into tea plantations due to the drivers of economic benefits. However, the changes in the soil microbial community and their potential function during the transition from a typical forest ecosystem to tea plantations remain poorly understood. This study investigated the soil microbial community in tea plantation soils with different planting ages, i.e., 6, 12, 23 and 35 years, and in an adjacent woodland control. We discovered that tea planting significantly increased soil bacterial richness (ACE and Chao1) and decreased fungal richness, the diversity of bacteria (Simpson and Shannon) show a trend of initially decreasing and then increasing while there was no significant effect on fungal diversity. After tea planting, the relative abundances of Actinobacteria and Proteobacteria increased by 180.9%–386.6% and 62.3%–97.5%, respectively; the relative abundances of Acidobacteria decreased by 11.4%–66.8%. However, the fungal phyla were not significantly different among different aged tea plantations and woodlands. FAPROTAX and FUNGuild revealed that the transition of natural woodland to tea plantations significantly increased the relative abundances of aerobic_chemoheterotrophy (14.66%–22.69%), chemoheterotrophy (34.36%–37.04%), ureolysis (0.68%–1.35%) and pathogenic fungi (26.17%–37.02%). db-RDA proved that the bacterial community structure was more strongly related to soil pH and available nitrogen (AN), while the main determinants of the fungal community composition were soil pH and soil organic matter (SOM). These findings indicate that tea planting has a strong effect on the soil microbial community and potential function. The change in soil pH during tea planting was the most important factor affecting the soil microbial community, while soil bacteria were more sensitive to tea planting than fungi.

Biochar is an eco-friendly material that influences heavy metals adsorption. Three kinds of bean shell biochar, namely, peanut, pea, and soybean biochar, were prepared at pyrolysis temperatures of 400 °C, 500 °C, and 600 °C. The characteristics of these biochars and the physicochemical properties of the biochars were analyzed. The capacities of the different biochars to adsorb Pb and Cd from aqueous solution were determined. With increasing pyrolysis temperature, the relative content of carbon in the biochar increased and that of hydrogen decreased, the porosity decreased, and the specific surface area increased; accordingly, the adsorption capacity of the biochar for Pb and Cd increased. The Pb adsorption capacity of the peanut shell biochar prepared at 400 °C was lower than that of the other shell biochars when the initial Pb concentration was at a low concentration. Three adsorption isotherm models were used to fit the adsorption processes of Pb or Cd on the three different biochars. The Freundlich curves better fit the adsorption capacity of biochar for Cd, and the Freundlich and Langmuir curves better fit the adsorption capacity of biochar for Pb. This work provides a scientific basis for the rational selection of bean shell biochar used in metal-contaminated water.

The dynamic response of soil bacterial communities to fertilization throughout the entire crop growth cycle remains inadequately characterized. To address this, we conducted a long-term field experiment in Jiangle County, Fujian Province, China, and collected soil samples across four rice growth stages (tillering, elongation, filling and maturity) under five fertilization regimes: no fertilization (CK); chemical fertilizer (NPK); and NPK supplemented with extra nitrogen (NPKN), extra phosphorus (NPKP) and rice straw (NPKS). Bacterial communities were analyzed by high-throughput sequencing. Our results revealed that soil bacterial diversity decreased progressively throughout the growth stages, with fertilization exerting only a minor influence. Structural equation modeling (SEM) identified daily mean temperature (DMT) as the factor with the strongest direct and total effects on the diversity. In contrast, fertilization regimes were the primary determinant of the community structure. Mantel test and redundancy analysis (RDA) indicated that soil pH was the most important factor shaping the community structure. Soil bacterial network attributes also varied mainly with fertilization: fertilizer addition reduced the complexity but enhanced stability, with NPK and NPKS showing the greatest stability. Regarding rice yields, all fertilized treatments were comparable but considerably higher than CK. In conclusion, rice growth stages primarily influenced soil bacterial diversity, while fertilization regimes predominantly shaped the community structure and network attributes. Further, we recommend NPK and NPKS as optimal strategies for balancing crop production, agroecosystem sustainability and environmental health.

Camellia oleifera Abel, recognized as one of the world’s four major woody edible oil sources, is extensively cultivated in the acidic red soil regions in southern China. This study focused on C. oleifera seedlings to investigate the mechanisms through which phosphorus (P) mitigates aluminum (Al) toxicity. The seedlings were subjected to various P–Al solutions at different concentration ratios, and a metabolomic analysis of their leaves was then conducted. The analysis identified a total of 509 metabolites, predominantly flavonoids and tannins. Among these, 466 flavonoids showed significant increases across all comparison groups, whereas 35 differentially abundant metabolites were consistently detected. Kyoto Encyclopedia of Genes and Genomes functional annotation and enrichment analysis highlighted the isoflavone biosynthesis pathway as the most significantly enriched pathway among the differentially abundant metabolites. Key metabolites identified as significantly differentially abundant included glycitin, naringenin, and 3,9-dihydroxypterocarpan. This research elucidates the metabolic alterations in C. oleifera seedlings under P and Al stress, suggesting that changes in flavonoid metabolites and the activation of the isoflavone biosynthesis pathway may be crucial adaptive strategies for C. oleifera to withstand such stresses. The findings not only offer a theoretical foundation for enhancing plant stress resistance but also provide valuable insights into the cultivation and management practices of C. oleifera.