Vineyard Age Mediates Soil Organic Phosphorus Turnover via Phosphodiesterase, Acid Phosphomonoesterase and phoC Gene

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.