Soil phosphorus (P) availability is critical for vineyard productivity, and pqqC-harboring bacteria contribute to inorganic P (Pi) mobilization. However, knowledge of the coordinated responses of Pi partitioning and pqqC-harboring bacteria to prolonged grape cultivation remains limited. Here, soils from 20-year-old grape orchards (Y20) and adjacent uncultivated soils (CK) were compared to explore the relationships among Pi fractions, pqqC-harboring communities, and edaphic characteristics. Relative to CK, Y20 showed significantly lower pH and higher concentrations of labile and moderate labile Pi fractions. Although the pqqC gene abundance declined significantly in Y20, the Shannon diversity of pqqC-harboring communities increased, and community composition differed markedly between the two land-use types. Soil pH and labile Pi were the main factors shaping community composition. Network analysis revealed strong associations between pqqC-harboring taxa and soil P fractions, with Azospira serving as a key connector. Pearson correlation analysis further showed that labile and moderately labile Pi fractions were negatively correlated with soil pH and pqqC gene abundance, while NaHCO₃-Pi was positively correlated with the Shannon diversity. Overall, long-term grape cultivation redistributed soil Pi toward more bioavailable forms, closely associated with soil acidification and shifts in the abundance and diversity of pqqC-harboring communities.

Organic phosphorus (OP) transformation in perennial orchard soils is strongly regulated by planting duration. However, the pathways of soil OP turnover in the orchards with different planting years remain largely unknown. This study was conducted in Penglai District, Shandong Province, China, characterized by a warm-temperate continental monsoon climate and brown sandy loam soil. Soil samples were collected from the 0–20 cm layer of vineyards established for 0.5, 4, 16, and 22 years (Y0.5, Y4, Y16, and Y22, respectively). Soil P pools, OP forms determined by solution ³¹P nuclear magnetic resonance spectroscopy, acid and alkaline phosphomonoesterase (ACP and ALP), phosphodiesterase (PDE) activities, and the diversity and composition of phoC- and phoD-harboring bacterial communities were analyzed. Differences among vineyard ages were assessed using one-way ANOVA, while principal coordinate analysis, canonical correlation analysis, and structural equation modeling were employed to evaluate microbial community variation and the relationships among soil properties, functional bacterial communities, phosphatase activities, and OP forms. We observed that compared with that in Y0.5, total P content in Y4 was significantly lower, whereas available P (AP) content in Y16, and OP content in both Y16 and Y22, were significantly higher. The contents of orthophosphate, myo-inositol hexakisphosphate (myo-IHP), scyllo-IHP, choline phosphate and corrected monoester (cMonoester) in Y16 and Y22 were significantly higher than that in Y0.5. Soil ACP activity in Y16 was significantly higher than that in Y4, but ALP and PDE activities in Y16 were significantly lower than those in other planting years. The phoC- and phoD-harboring community composition in Y16 was significantly altered, with phoC- and phoD-harboring community α-diversity remarkably increased and decreased, respectively. The phoC- and phoD-harboring community composition was driven by soil pH, AP and cMonoester, with phoD-harboring community composition predicted by the soil C:P ratio. Soil OP transformation is mainly regulated by the activity of PDE and ACP, and the diversity and composition of phoC-harboring communities, in orchards with different planting years.

Long-term grape cultivation alters soil acid–base properties and nitrogen transformation processes, yet the mechanisms underlying the changes in soil physical and chemical properties as well as nitrogen components remain unclear. In this study, four grape vineyards with cultivation ages of 0.5 (newly established, Y0.5), 4 (Y4), 16 (Y16), and 22 years (Y22) in Penglai, Yantai, China, were selected as research subjects. Soil nitrogen pools, key nitrogen hydrolase activities, and chiA gene community assembly, as well as their internal regulatory relationships were investigated. The results revealed that cultivation age significantly reshaped soil nitrogen speciation: Y16 vineyards exhibited the highest concentrations of total nitrogen, mineral nitrogen, microbial biomass nitrogen, and labile hydrolyzable ammonium nitrogen (HAN), representing a critical inflection point of soil nitrogen supply capacity. With prolonged cultivation to 22 years, soil nitrogen pools shifted toward recalcitrant stable organic nitrogen (stable-SON), accompanied by significant accumulation of amino sugar nitrogen (ASN). Activities of N-acetyl-β-D-glucosaminidase (NAG), urease, amidase and leucine aminopeptidase were markedly suppressed in Y16 soils. Both Chao1 richness and Shannon diversity indices of chiA gene communities reached the minimum values at 16 years, and PCoA confirmed distinct community separation of Y16 from other age groups. Soil pH, ammonium nitrogen and nitrate nitrogen were the dominant environmental filters governing chiA community composition. Actinomycetota and Pseudomonadota dominated the chiA-harboring microbiota, with acid-tolerant Streptomyces significantly enriched in Y16, while keystone genera Nonomuraea and Pseudoxanthomonas mediated the conversion between labile and stable organic nitrogen pools. Redundancy analysis demonstrated that chiA community composition (25.5% explanation), chiA α-diversity (19.3% explanation), and NAG activity (14.6% explanation) were the primary drivers of soil organic nitrogen fraction variation. Results support a four-level cascading framework wherein stand-age-induced soil acidification and altered N inputs drive shifts in chiA-harboring microbial diversity and community structure, which in turn modulate nitrogen hydrolase activities and ultimately govern the reciprocal transformation between labile and stable organic nitrogen pools, resulting in stage-specific nitrogen supply capacity. This study clarifies the microbial gene–enzyme–nitrogen pool coupling mechanism in chronosequence vineyards and provides theoretical guidance for targeted nitrogen management of aged vineyards.

Organic phosphorus (OP) transformation in perennial vineyards is strongly influenced by long-term cultivation, fertilization, and associated changes in soil properties. However, the relationships among soil OP speciation, phosphatase activities, and phoC- and phoD-harboring bacterial communities remain poorly understood. In this study, soils from 20-year-old vineyards (Y20) and adjacent uncultivated reference sites (CK) in Penglai, China, were compared. Soil available P was significantly higher in Y20 than in CK, increasing from 15.83 to 40.50 mg kg⁻¹, whereas total P, OP, and microbial biomass P did not differ significantly between treatments. The contents of soil orthophosphate and corrected monoesters (cMonoesters) were in the range of 15.34–97.45 and 6.90–24.49 mg kg⁻¹, respectively, and were significantly higher in Y20 than in CK. Among the identified monoesters, the mean concentrations of myo-inositol hexakisphosphate (myo-IHP), scyllo-IHP, and choline phosphate in Y20 were 4.12, 0.69 and 0.69 mg kg⁻¹, respectively, significantly higher than those observed in CK. The Y20 soils also exhibited 17.94% higher acid phosphomonoesterase (ACP) activity and 28.05% lower alkaline phosphomonoesterase (ALP) activity than the CK soils. Furthermore, the α-diversity of phoC-harboring bacteria was lower in Y20, whereas the composition of phoD-harboring communities differed significantly between the two land-use types. Correlation analyses showed that soil OP forms correlated positively with ACP activity and phoD community composition, but negatively with ALP activity. Overall, the differences between Y20 and CK suggest that long-term vineyard cultivation was associated with increased P availability through redistribution among soil P forms and with the accumulation of relatively stable cMonoesters. These patterns were closely related to phosphomonoesterase activities and the composition of phoD-harboring bacterial communities. These findings highlight the potential interactions among P speciation, phosphatase activities, and functional microbial communities in vineyard soils and provide hypotheses for further investigation of P transformation processes.