Soil salinization poses a global threat to terrestrial ecosystems. Soil microorganisms, crucial for maintaining ecosystem services, are sensitive to changes in soil structure and properties, particularly salinity. In this study, contrasting dynamics within the rhizosphere and bulk soil were focused on exploring the effects of heightened salinity on soil microbial communities, evaluating the influences shaping their composition in saline environments. This study observed a general decrease in bacterial alpha diversity with increasing salinity, along with shifts in community structure in terms of taxa relative abundance. The size and stability of bacterial co-occurrence networks declined under salt stress, indicating functional and resilience losses. An increased proportion of heterogeneous selection in bacterial community assembly suggested salinity’s critical role in shaping bacterial communities. Stochasticity dominated fungal community assembly, suggesting their relatively lower sensitivity to soil salinity. However, bipartite network analysis revealed that fungi played a more significant role than bacteria in intensified microbial interactions in the rhizosphere under salinity stress compared to the bulk soil. Therefore, microbial cross-domain interactions might play a key role in bacterial resilience under salt stress in the rhizosphere.

The decline in agricultural productivity because of soil salinization has become a global problem in recent years. Biofertilizers show great potential for soil improvement as a sustainable strategy; however, their effectiveness in improving saline soils and enhancing plant growth under saline stress is poorly understood. We assessed the effectiveness of biofertilizers in improving saline soils and enhancing crop growth under saline stress and investigated the related potential mechanisms. Changes in soil physicochemical properties, plant physiological parameters, and soil microbial communities were analyzed using pot experiments. The results showed that biofertilizer application reduced total soluble salts in the soil by 30.8% and increased Brassica rapa L. biomass by 8.4 times. Biofertilizer application increased soil organic matter, total nitrogen, and available phosphorus by 56.1%, 57.0%, and 290%, respectively. Simultaneously, superoxide dismutase, catalase, chlorophyll a, chlorophyll b, total soluble sugar, and proline levels also increased by 89.5%, 140%, 110%, 190%, and 130%, respectively. Biofertilizers increased the abundance of Bacillus and Planococcus and decreased the abundance of Mortierella and Aspergillus, which could potentially be the underlying reason for the promotion of plant growth. Overall, the results of this study demonstrate the efficacy of biofertilizers in improving saline soils and that the application of biofertilizer could greatly promote agricultural production.

Constructed wetlands (CWs) are widely used for wastewater treatment but can also serve as significant sources of nitrous oxide (N₂O), a potent greenhouse gas. Balancing efficient nitrogen removal with N₂O mitigation remains a critical challenge for sustainable wastewater management. This review systematically elucidates the key microbial mechanisms underlying N₂O emissions in CWs and summarizes corresponding mitigation strategies. Mechanistically, N₂O production is primarily driven by hydroxylamine oxidation and nitrifier denitrification mediated by ammonia-oxidizing microorganisms, as well as incomplete heterotrophic denitrification resulting from electron-donor limitation. These pathways are tightly regulated by spatiotemporal redox gradients, carbon-to-nitrogen ratios, and influent strength conditions. To address these emissions, this review synthesizes mitigation strategies from an engineering perspective. Optimization of operational parameters, such as intermittent aeration and water-level regulation, together with the application of novel functional substrates, such as biochar and iron-carbon micro-electrolysis, can effectively facilitate electron transfer and improve micro-redox conditions. Furthermore, optimized plant species selection and community design, along with emerging low-carbon biological nitrogen removal processes, such as autotrophic denitrification and partial denitrification coupled with anammox, offer promising approaches for substantial emission reduction. Overall, this review provides practical guidance for designing efficient, low-carbon CWs toward carbon neutrality.

Saline-alkali soils are characterized by high salt content and low organic matter, which hinders plant growth and limits their carbon sequestration capacity. Using of biofertilizer has been recognized as a promising strategy for saline-alkali soil improvement. This study evaluated the potential of biofertilizer to improve the saline-alkali soil properties and enhance carbon sequestration through field experiments, while also exploring the underlying mechanisms. The soil supplemented with 30 and 60 t·ha-1 of biofertilizer resulted into an increase in per-hectare carbon sequestration by 102 t CO2e and 144 t CO2e, respectively, in comparison to soil without biofertilizer (control). The improvement in soil properties showed an increase in Suaeda salsa biomass, enhancements in soil enzymes activities and elevation in total organic content, as evident by correlation analysis and Mantel tests. Furthermore, the metabolism of organic matter promotes an increase in total inorganic carbon. The results indicates that the use of biofertilizer is an effective strategy for improving saline-alkali soil and enhancing carbon sequestration.