Soil microbial communities play a crucial role in maintaining diverse ecosystem functions within the saline-alkali soil ecosystems. Therefore, in this study, we collected various saline-alkaline soils from across the Inner Mongolia Hetao irrigation area. The soil chemical properties were analyzed, and the microbial diversity of bacteria and fungi was measured using 16 S rRNA and ITS rRNA amplicon sequencing. The dynamic relationship between the soil microbial community and soil factors was analyzed using the ABT (Aggregate Enhanced tree) model, the co-occurrence network, and the structural equation model. The results indicated that electrical conductivity (EC) was the biggest driving force of various saline-alkaline soils, affecting the community structure of bacteria (22.80%) and fungi (21.30%). The soil samples were categorized into three treatment levels based on their EC values: the low-salinity group (L, EC: 0–1 ms/cm, n = 10), the medium-salinity group (M, EC: 1–2 ms/cm, n = 8), and the high-salinity group (H, EC > 2 ms/cm, n = 6). The results demonstrated a negative correlation between microbial abundance and salinity-alkalinity, while revealing an enhanced interrelationship among species. The alterations in bacterial (12.36%) and fungal (22.92%) communities in various saline-alkali soils were primarily driven by saline-alkali ions, which served as the principal direct factors. The negative correlation between EC and SOM exhibited the highest magnitude, whereas the positive correlation between soil organic carbon and EC demonstrated the greatest strength. Therefore, it was further substantiated that EC played a pivotal role in shaping the distinct microbial communities in saline-alkali soils.

Corn straw is an important renewable resource, which could improve the quality of saline–alkali cultivated land. However, the slow decomposition of crop residues in cold, arid, and saline–alkali soils can lead to serious resource waste and ecological crises. The use of beneficial microorganisms with degradation functions could solve these problems. In this study, three types of saline–alkali soil with low, medium, and high salinity levels were used in the straw-returning experiment. The experiment was conducted with four treatments: GF2 (Klebsiella sp.), GF7 (Pseudomonas sp.), GF2+GF7, and CK (control without bacteria). Microbial characteristics, straw degradation efficiency, element release rate, and soil factors were compared, and random forest linear regression and partial least squares path modeling analysis methods were utilized. The results indicated that the degradation of bacterial metabolites, the efficiency of corn stover degradation, the efficiency of component degradation, and the release rates of elements (C, N, P, and K) initially increased and then decreased with the increase in salinity. At the maximum value of moderately saline–alkali soil, the effect of GF2+GF7 treatment was significantly better than that of other treatments (p < 0.05). Given the interactive effects of saline–alkali soil and microbial factors, the application of exogenous degrading bacteria could significantly increase soil enzyme activity and soil available nutrients, as well as regulate the salt–alkali ion balance in soil. The cation exchange capacity (9.13%, p < 0.01) was the primary driving force for the degradation rate of straw in saline–alkali soil with different degrees of salinization under the influence of exogenous degrading bacteria. Straw decomposition directly affected the soil chemical properties and indirectly affected soil enzyme activity. The results of this study would provide new strategies and insights into the utilization of microbial resources to promote straw degradation.

The increasing salinization of cultivated soil worldwide has led to a significant reduction in maize production. Using saline–alkaline-tolerant growth-promoting bacteria (PGPR) in the rhizosphere can significantly improve the saline tolerance of maize and ensure the stability of maize yields, which has become a global research hotspot. This study screened salt-tolerant microorganisms Klebsiella sp. (GF2) and Pseudomonas sp. (GF7) from saline soil to clarify the mechanism in improving the saline tolerance of maize. In this study, different application treatments (GF2, GF7, and GF2 + GF7) and no application (CK) were set up to explore the potential ecological relationships between the saline tolerance of maize seedlings, soil characteristics, and microorganisms. The results showed that co-occurrence network and Zi-Pi analysis identified Klebsiella and Pseudomonas as core microbial communities in the rhizosphere soil of maize seedlings grown in saline soil. The deterministic process of microbial assembly mainly controlled the bacterial community, whereas bacteria and fungi were governed by random processes. The application of saline–alkaline-resistant PGPR under saline stress significantly promoted maize seedling growth, increased the activity of soil growth-promoting enzymes, and enhanced total nitrogen, soil organic carbon, and microbial carbon and nitrogen contents. Additionally, it reduced soil salt and alkali ion concentrations [electrical conductivity (EC) and exchangeable Na⁺]. Among them, GF2 + GF7 treatment had the best effect, indicating that saline–alkaline-tolerant PGPR could directly or indirectly improve the saline tolerance of maize seedlings by improving the rhizosphere soil ecological environment. EC was the determining factor to promote maize seedling growth under saline–alkaline stress (5.56%; p < 0.01). The results provided an important theoretical reference that deciphers the role of soil factors and microecology in enhancing the saline tolerance of maize.

Solid bacterial agents are required to accelerate stover degradation in low-temperature areas. However, the laboratory-to-practice translation of bioprocessing techniques is hindered by high cost, poor practicality, and short shelf life. Using corn stover powder, starch, and bran as additives, we screened Pseudomonas putida and Acinetobacter lwoffii, which effectively degrades corn stover at low temperatures, to develop a sustainable and low-cost bacterial agent formula that ensures bacterial viability in low-temperature soil and storage. The optimal formulation included precipitates and additives at a 1:4 ratio, including corn stover powder, starch, and bran at a 4:3:9 ratio. The viable bacterial count with this formulation reached 7.5 × 10¹⁰ colony-forming units/g, with high lignocellulase activities. The degradation effect of the optimal formulation on stover and its components, in both lab soil culture simulation and the field environment, was significantly higher than that without bacterial agent application. This formulation had an outstanding effect on lignin. The optimal storage conditions included vacuum packing under 10% water content at 4 °C; the survival rate of viable bacteria reached 85.33% after 180 d. Given the global value of stover-return agriculture, our results offer a valuable strategy for application in low-temperature soils where stover degradation rates are otherwise low.