Rhizosphere microbiota are conducive to soil nutrient cycling for plant growth. Long-term and excessive application of chemical fertilizer is harmful to agriculture. Seaweed extract is a good organic substitute for rhizosphere ecosystem and plant growth. We supplemented 5‰ seaweed extract powder to chemical fertilizer, and then studied its effect on rhizosphere bacteria of japonica rice (Oryza sativa L. subsp. japonica). In a short-term experiment, we compared the changes in rhizosphere bacteria among four treatments, i.e., no fertilizer (T1), chemical fertilizer only (T2), chemical fertilizer with 5‰ seaweed extract (T3), and less chemical fertilizer with 5‰ seaweed extract (80% of that of T3) (T4). Results show that seaweed extract supplement could affect the bacterial community in tillering and heading stages; the α-diversity of rhizosphere bacteria in the heading stage was obviously improved. In addition, seaweed extract supplement improved significantly the content of nitrate nitrogen (N), available phosphorus (P), and available potassium (K) in rhizosphere soil in the tillering stage, and, finally, increased the rice yield and quality mildly. Therefore, the seaweed extract supplement is shown to be a potential strategy to enrich the diversity of rhizosphere bacteria, which enhanced soil nutrient level, increased rice yield and quality, and also saved the use of chemical fertilizer.

Climate-driven extremes in precipitation are fundamentally altering the hydrological regimes of wetland ecosystems. However, the mechanistic understanding of how soil microbial communities and their metabolic functions respond to precipitation change, and how these responses regulate soil organic carbon (SOC) dynamic, remains limited. Here, we leveraged a 7-year precipitation manipulation experiment (±40%) in a coastal wetland and applied genome-resolved metagenomics to systematically examine microbial community structure, ecological networks, and key biogeochemical functions (carbon fixation and degradation). We found that although microbial community structure showed no pronounced response to increased precipitation, decreased precipitation reorganized the community, as evidenced by higher β-diversity and more complex co-occurrence networks with strengthened positive interactions. Compared with dominant species, rare species played a more important role in maintaining the stability of microbial networks. Functional potential for carbon degradation and fixation remained relatively stable under decreased precipitation. In contrast, increased precipitation concurrently suppressed degradation of polysaccharides and aromatic compounds, and some carbon fixation pathways, such as Acetyl-CoA (rAcCoA) pathway. Collectively, decreased and increased precipitation induced asymmetric responses in microbial communities, with decreased precipitation primarily reshaping community composition but having little effect on functional potential, whereas increased precipitation predominantly altered functional profiles without substantially changing community structure. We further found microbial community reassembly decoupled SOC content. Together, this study highlights that prolonged precipitation extremes shape coastal wetland microbiomes through divergent ecological trajectories; however, these microbial shifts may not necessarily translate directly into changes in soil carbon storage.