Deep tillage alters the structure of bacterial subcommunity to improve crop yield in a rice-wheat annual rotation system

Abstract

Soil bacteria play vital roles in maintaining the functionality and stability of agroecosystems. However, how the bacterial subcommunity (abundant versus rare) responds to agricultural management and the subsequent impacts on crop productivity remain poorly understood. To address this question, a split-plot experiment [tillage practice (rotary tillage, RT; no-tillage, NT; deep tillage, DT) was conducted as the main plot and soil compartment (rhizosphere soil, RS; bulk soil, BS) as the subplot] was conducted to investigate the responses of bacterial subcommunity assembly processes, as well as their subsequent impacts on wheat and rice yield. Our results demonstrated that the removal of abundant taxa significantly improves the robustness of bacterial network structure (78.86 %∼103.08 %) compared to the removal of rare taxa, indicating that rare taxa are more important in maintaining the stability of bacterial community. Moreover, the rare taxa subcommunity showed higher diversity than the abundant taxa, and the assembly of rare taxa was primarily driven by stochastic process, while it was mainly determined by niche process for abundant taxa. Furthermore, DT greatly increased the relative abundance of Bacteroidota in the abundant and rare taxa of the bulk soil during the rice season. The wheat and rice grain yield was also increased by DT (6.98 %∼19.36 %) compared to RT. Structural equation modeling further demonstrated that soil nutrients directly enhanced enzymatic activity to increase rice yield, while also exerting indirect effects through mediation of the structure of both dominant and rare bacterial subcommunities, ultimately influencing wheat productivity. Collectively, these findings shed new lights on the structure and assembly of bacterial subcommunities in agroecosystems and underscore their potential influence on crop productivity.