## 3 Discussion
### H\({}_{2}\) Supply Displays the Positive Effects on Microbial-Mediated Soil C, N, and P Cycles  
Since the changed structure of the rhizosphere microbial community can potentially lead to alterations in its function [35], C, N, and P cycling in the rhizosphere microbiome was subsequently analyzed. As anticipated, the metagenomic analysis revealed that the microbial C, N and P cycles differed significantly between H\({}_{2}\) supply condition and the corresponding controls, especially in the unfertil treatment. Previous studies showed that the capacity for C fixation, primarily through Calvin cycle (_rbCL_), was increased by H\({}_{2}\) in wetland and upland soils [30]. Consistently, H\({}_{2}\)-based irrigation increased the relative abundance of genes involved in C fixation (e.g., Calvin cycle and reductive citrate cycle genes), while contrasting responses were observed in genes related to organic C degradation (e.g., cellulose- and hemicellulose-degradation genes), all of which were more pronounced upon the non-fertilization condition (Figure 3 and Supplementary Table S5). Previous studies showed that H\({}_{2}\) stimulation of \(\beta\)/\(\gamma\)-Proteobacteria was accompanied by the increased net CO\({}_{2}\) fixation [4]. Therefore, we speculated that an increase in the potential microbial C fixation and a reduction in microbe-mediated soil C loss might be achieved by H\({}_{2}\)-based irrigation. For N cycling, controversial results of related works exist. For example, based on H\({}_{2}\) infusion, one is that it did not impact the abundances of N cycle genes in the lawnt kept free of vegetation [24], and another finding showed that the increased _napA_ and _nirS_ relative abundance and decreases in _norB_ abundance in high (2% and 5%) H\({}_{2}\)-treated soils were present in the paddy wetland/meadow upland [30]. The data from the present study demonstrate that, under unfertilized conditions, the level of DNRA (i.e., _napAB_ and _nrfAH_) were remarkably increased by H\({}_{2}\) supply (Figure 4A and Supplementary Table S5), reflecting the possibility that the increased potential of soil NH\({}_{4}\)+-N derived from NO\({}_{3}\)\({}^{-}\)-N after H\({}_{2}\)-based irrigation, ultimately leading to strawberry growth and yield promotion due to the preference of strawberry for NH\({}_{4}\)+-N [36]. Since DNRA competes with denitrification for NO\({}_{3}\)\({}^{-}\), genes (notably _nirK_ and _norB_) for denitrification, the main N-loss process in the agricultural soil [37] were also less abundant by H\({}_{2}\). By contrast, a previous result showed the increased N\({}_{2}\)O emissions and _nirK_ abundance in soil adjacent to legume nodules and in HOB isolate-inoculated corn soil [38]. These discrepancies in nitrification and denitrification might be due to the microorganism responses to H\({}_{2}\) supply in different plant species, and also in the various H\({}_{2}\) supply conditions and concentrations used in each case. Phosphate-solubilizing bacteria dominating in the agricultural soils can release recalcitrant phosphate, thus improving crop nutrient acquisition and crop productivity [39]. In the present study, certain phosphate-solubilizing microorganisms, such as _Burkholderia_, _Pseudomonas_, and _Sphingomonas_, were enriched by H\({}_{2}\) supply (Figure 2D and Supplementary Table S3). The activated microbial P metabolism was also observed, which was evaluated by the increased abundance of genes responsible for P transportation (_ugpABCE_), inorganic P solubilization (_ppx-gppA_), and organic P mineralization (_phoD_ and _appA_; Figure 4B and Supplementary Table S5). These results clearly implicated the improved microbial efficiency of utilizing and internalizing soil P, thus converting the unavailable P into available forms for the crop absorption [40]. Compared to conditions without fertilization, in the presence of fertilizers, the impact of H\({}_{2}\)-based irrigation on soil microbial communities was relatively weaker, which might be attributed to the addition of Bacillus.