Geoderma (Aug 2024)
The accumulation of fungal not bacterial residue carbon is management-dependent under conventional and organic practices in apple-orchard soil
Abstract
Organic orchard management has been widely adopted to enhance soil fertility by improving the sequestration of soil organic carbon (SOC). Microbial residue carbon plays an essential role in SOC accumulation; nevertheless, how fungal and bacterial residue carbon (FRC and BRC) changes with different orchard management practices (organic vs. conventional) and the factors influencing their accumulation remain poorly understood. In this study, we quantified the FRC and BRC in the two management practices, compiled this data with the comparisons of plant, soil and microbial properties, and the dominant factor affecting their sequestration was ascertained with a 4-year orchard experiment on the Jiaodong Peninsula. Compared with conventional management, organic management significantly enhanced SOC and the accumulation of FRC and BRC, while it did not alter the contribution of FRC or BRC to SOC. Furthermore, we identified that the primary determinant affecting FRC varied with management type: Plant (AGR, BGG)-soil (SOC, density)-microbe (Nitrospirae) collectively governed FRC in organic soil, whereas soil (pH, density) and microbial (Ascomycota) properties regulated FRC in conventional soil. Nitrospirae abundance and soil pH played pivotal roles in FRC accumulation under organic and conventional management, respectively. Meanwhile, the primary factor influencing BRC was independent of management type: Soil and microbial properties consistently served as the principal determinants of BRC in both management systems, with soil pH and clay being the pivotal factors in organic and conventional managements, respectively. These findings illustrate the divergent regulatory mechanisms of FRC and BRC in organic and conventional management, thereby enhancing our comprehension of microbial-mediated SOC sequestration in organic orchard management.
