Co-analysis of rhizosphere metabolomics and bacterial community structures to unfold soil ecosystem health in Camellia oleifera land under long-term cultivation

Long-term cultivation of woody species would change soil microbial community and metabolites composition, and then affect soil ecological function. Camellia oleifera is an important economically cultivar grown in subtropical regions of China but its effect on soil quality and health remains unclear. Soil bacterial communities and metabolome composition are investigated in this study via high-throughput sequencing and soil metabolomics to determine soil quality under different growth stages (sapling, maturity, and degeneration periods) of C. oleifera. Main results revealed that soil metabolite composition reaches equilibrium faster than microorganisms. Higher carbohydrate content (such as trehalose, mannopyranose, and sucrose) during degeneration stages of C. oleifera induces the decrease of Chloroflexi and Actinobacteria abundances and results in lower disease resistance potential than that of sapling and mature stages. Long-term cultivation of C. oleifera soil showed significantly higher abundance of carbon, nitrogen, and phosphorus metabolism, and presented significantly higher soil organic matter, available nitrogen, and available phosphorus contents. Results demonstrated that long-term C. oleifera cultivation can significantly improve soil fertility but potentially cause the decline of soil ecological health. •Soil metabolite composition reached equilibrium more quickly than microorganisms did•Soil carbohydrate content may play an important role in regulating soil ecological function•Long-term C. oleifera cultivation could significantly improve soil fertility but suppress soil ecological health