Aims Improving the functionality of saline-alkali lands and mitigating the emissions of microbial greenhouse gas (GHG) are crucial for enhancing soil C storage in terrestrial ecosystems. Peat addition and phytoremediation are considered effective strategies for saline-alkali land remediation, but the underlying interactive effects on carbon dioxide (CO₂) and nitrous oxide (N₂O) emissions remain unclear.
Methods We assessed the effects of peat amendments at two levels (6 g/kg, 18 g/kg) in combination with two halophytic plants (Suaeda salsa as a pioneer species that may improves soil structure and reduces salinity, Suaeda glauca as an indicator species tolerant of salt stress and associated with nutrient accumulation). We then measured changes in soil and microbial properties, and thus CO₂ and N₂O emissions.
Results Peat amendments and halophytes significantly influenced soil properties, fungal community composition and bacterial diversity. Peat addition with low-concentration significantly inhibited CO₂ emissions in S. salsa, with bacterial alpha diversity and ammonium N content positively correlated with this inhibition, while fungal community composition had a negative effect. In contrast, peat addition had no significant effect on CO₂ emissions in S. glauca. Peat additions at both low and high-concentration significantly increased N₂O emissions in S. salsa, with positive correlation to soil total C/N, dissolved organic C/ total dissolved N, and nitrate N. In contrast, peat addition had no significant effect on N₂O emissions in S. glauca.
Conclusions Peat additions-mediated GHG emissions depend on halophytes-specific responses. Compared with the S. glauca, peat addition to the pioneer plant S. salsa significantly reduced CO₂ emissions, yet increased N₂O emissions, providing a framework for optimizing peat–halophyte combinations to mitigate GHG emissions.
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