Saline Soil Environment Research Articles

Study on Evaluation and Prediction Model of Long-term Mechanical Properties of Fine-grained Saline Soil Subgrade

In this thorough examination, we dive deep into the long-lasting mechanical characteristics of fine-grained saline soil subgrades, aspiring to establish a precise and reliable collection of predictive models. Our objective is to provide a solid scientific footing for the design and ongoing upkeep of road networks within saline soil environments. Analyzing prolonged monitoring data across diverse highway subgrades within a prototypical saline soil locale, we unveil the intricate temporal fluctuations and environmental sensitivities of the soil’s mechanical properties under continuous load. Precisely, the subgrade’s compressive modulus dwindled by 15%, while shear strength declined by 8% over a five-year period. These trends intensify during rainy and scorching seasons, with drops surpassing 20% and 12% respectively. Leveraging this intricate data, we deploy nonlinear regression analysis and sophisticated machine learning algorithms to construct a predictive model tailored for the long-term mechanical properties of fine-grained saline soil roadbeds. This model integrates a multitude of factors, including load duration, temperature, humidity, and more, delivering accurate forecasts of key subgrade indicators like compressive modulus, shear strength, and beyond. In the verification stage, compared with the measured data, the error rate of the model prediction results is controlled within 5%, showing high prediction accuracy and stability. In addition, we also carried on the sensitivity analysis to the model, found that the load size and the duration of the impact on the mechanical properties of the roadbed is the most significant. Therefore, in the design of road engineering in saline soil areas, the influence of these factors should be fully considered, and reasonable engineering measures should be taken to ensure the safety and durability of roads. This study not only provides effective data support for the long-term mechanical performance evaluation of fine-grained saline soil roadbed, but also provides an important theoretical reference for engineering practice in related fields.

Genome-wide identification and expression analysis of the PP2C gene family in Apocynum venetum and Apocynum hendersonii

BackgroundProtein phosphatase class 2 C (PP2C) is the largest protein phosphatase family in plants. Members of the PP2C gene family are involved in a variety of physiological pathways in plants, including the abscisic acid signalling pathway, the regulation of plant growth and development, etc., and are capable of responding to a wide range of biotic and abiotic stresses, and play an important role in plant growth, development, and response to stress. Apocynum is a perennial persistent herb, divided into Apocynum venetum and Apocynum hendersonii. It mainly grows in saline soil, deserts and other harsh environments, and is widely used in saline soil improvement, ecological restoration, textiles and medicine. A. hendersonii was found to be more tolerant to adverse conditions. The main purpose of this study was to investigate the PP2C gene family and its expression pattern under salt stress and to identify important candidate genes related to salt tolerance.ResultsIn this study, 68 AvPP2C genes and 68 AhPP2C genes were identified from the genomes of A. venetum and A. hendersonii, respectively. They were classified into 13 subgroups based on their phylogenetic relationships and were further analyzed for their subcellular locations, gene structures, conserved structural domains, and cis-acting elements. The results of qRT-PCR analyses of seven AvPP2C genes and seven AhPP2C genes proved that they differed significantly in gene expression under salt stress. It has been observed that the PP2C genes in A. venetum and A. hendersonii exhibit different expression patterns. Specifically, AvPP2C2, 6, 24, 27, 41 and AhPP2C2, 6, 24, 27, 42 have shown significant differences in expression under salt stress. This indicates that these genes may play a crucial role in the salt tolerance mechanism of A. venetum and A. hendersonii.ConclusionsIn this study, we conducted a genome-wide analysis of the AvPP2C and AhPP2C gene families in Apocynum, which provided a reference for further understanding the functional characteristics of these genes.

Salt-tolerant plant growth-promoting bacteria as a versatiletool for combating salt stress in crop plants.

Soil salinization poses a great threat to global agricultural ecosystems, and finding ways to improve the soils affected by salt and maintain soil health and sustainable productivity has become a major challenge. Various physical, chemical and biological approaches are being evaluated to address this escalating environmental issue. Among them, fully utilizing salt-tolerant plant growth-promoting bacteria (PGPB) has been labeled as a potential strategy to alleviate salt stress, since they can not only adapt well to saline soil environments but also enhance soil fertility and plant development under saline conditions. In the last few years, an increasing number of salt-tolerant PGPB have been excavated from specific ecological niches, and various mechanisms mediated by such bacterial strains, including but not limited to siderophore production, nitrogen fixation, enhanced nutrient availability, and phytohormone modulation, have been intensively studied to develop microbial inoculants in agriculture. This review outlines the positive impacts and growth-promoting mechanisms of a variety of salt-tolerant PGPB and opens up new avenues to commercialize cultivable microbes and reduce the detrimental impacts of salt stress on plant growth. Furthermore, considering the practical limitations of salt-tolerant PGPB in the implementation and potential integration of advanced biological techniques in salt-tolerant PGPB to enhance their effectiveness in promoting sustainable agriculture under salt stress are also accentuated.

Experimental Study on Mechanical Properties of CFRP-Confined Concrete Columns under Continuous Semi-Submergence of Sulfate

To investigate the mechanical properties of carbon-fiber-reinforced-polymer (CFRP)-restrained concrete in a saline soil environment, the degradation of the mechanical properties of CFRP-restrained concrete columns under the effect of continuous sulfate semisoak erosion is investigated based on sulfate continuous semisoak erosion, and unrestrained concrete columns with the same specifications are used in comparison tests. The results show that the strength, stiffness, and ductility of both plain concrete columns and CFRP-confined concrete columns first increase and then decrease after the continuous semi-submersion erosion by sulfate; compared with plain concrete columns, the decline rates of strength and stiffness of CFRP-confined concrete columns are significantly lower, and the CFRP demonstrates a certain protective effect on the core concrete. Through a regression analysis of experimental data, strength and ultimate strain models of CFRP-confined concrete columns under the continuous semi-submergence of sulfate are proposed based on the existing ultimate strength and ultimate strain models of CFRP-confined ordinary concrete columns, and a stress–strain model of CFRP-confined concrete columns under the continuous semi-submergence of sulfate is established. Based on a comparison with experimental data, the model prediction curves indicate good agreement with the experimental curves and can therefore provide a theoretical basis and practical reference for CFRP-reinforced semi-submerged concrete in saline soil areas.

A Review of Waterborne Polymer–Cementitious Composite Repair Materials for Application in Saline Soil Environments: Properties and Progress

The properties of a large number of concrete infrastructures in China are deteriorating year by year, raising the need for repairing and strengthening these infrastructures. By introducing waterborne polymers into a cement concrete system, brittle cracks and easy bonding performance defects of concrete can be compensated for to form a long-life, semi rigid, waterborne polymer-modified cementitious repair material with a promising development prospect. This paper investigates the modification effect of polymer emulsions on ordinary cement mortar. Our research mainly focused on the physical and mechanical properties, durability, microstructure and application status of waterborne polymer-modified cementitious composites. Literature studies show that with the increase in waterborne polymer content (0 wt%~20 wt%), the performance of cement mortar significantly improves, which in turn expands its application range. Compared with ordinary cement mortar, the introduction of waterborne polymers blocks some of the pores in the cement to a certain extent, thus improving its permeability, freeze–thaw resistance and durability. Finally, this paper describes the application of waterborne polymer–cementitious composites in western saline soil environments, as well as discusses the prospects of their development.

Investigating the serve life of common earthed materials based on evaluations of the soil corrosion in offshore areas of East China

The serve life of common earthed materials in power systems is essentially affected by the soil environment, especially the potential corrosion problem of sodium chloride contaminated soil in offshore areas. This study measured the corrosion rates of three common earthed metal materials, Q235 carbon steel, pure Al, and H62 brass, in typical chloride saline soil using accelerated and field corrosion tests. The acceleration ratio and kinetic correlation coefficient under different acceleration conditions were calculated, and the laboratory and field corrosion time correlation models of common earthed metal materials were obtained. The results show a good correlation between soil accelerated and field corrosion tests. Under the same temperature and salinity, the correlation degree of Q235 carbon steel is larger when the water content is 30%. In comparison, the correlation degree of pure Al and H62 brass is larger when the water content is 20%. The laboratory and field corrosion time correlation models of Q235 carbon steel, pure Al, and H62 brass in chloride type saline soil environment are T1=18.32T0, T1=95.56T0, T1=15.78T0, which can effectively evaluate the serve life of common earthed metal materials in typical chloride type saline soil in the offshore area of East China.

Influence of Xinjiang Saline Soil on Corrosion of X80 Pipeline Steel

A large-scale gas transmission pipeline project will pass through typical saline soil areas in Xinjiang, China, to find out the influence of the saline soil on the long-distance pipeline in this area, this paper investigates the corrosive behavior of X80 pipeline steel embedded in saline soil with multiple corrosion intensities. Firstly, NaCl, Na2SO4, NaHCO3, and deionized water were used to simulate the saline soil with different corrosion intensities, and then the corrosion test of X80 steel was carried out. A scanning electron microscope was used to observe the X80 steel before and after corrosion. Finally, the weight loss method was used to calculate the corrosion rate, and the corrosive behavior of X80 pipeline steel in Xinjiang saline soil environment was analyzed. The results show that: (1) X80 steel is susceptible to pitting corrosion in the saline soil environment; (2) the rate and level of corrosion were mainly related to the content of Cl− and SO4 2−. The greater the content, the stronger the pipeline is corroded; (3) the rate and level of corrosion were positively correlated with the corrosion intensities of saline soils.

Response of Soil Fungal Community to Biochar Application Under Different Irrigation Water Salinity

Saline water irrigation can alleviate the shortage of freshwater resources in the northwest arid zone, but long-term saline water irrigation can damage the soil fungal community structure. To alleviate the harm caused by salinity, biochar is used as a soil amendment to improve the soil fungal community structure. To investigate the intrinsic link between biochar application and the structural diversity of fungal communities in saline soils, two irrigation water salinity levels were set:0.35 dS·m-1 (fresh water) and 8.04 dS·m-1 (saline water). At each irrigation water salinity, two levels of biochar application were set:0 t·hm-2 (no application) and 3.7 t·hm-2 (application). High-throughput sequencing results showed that compared to that under fresh water irrigation, saline water irrigation increased fungal community species diversity and decreased fungal community species richness; biochar application under saline water irrigation reduced soil fungal community species diversity and species richness. The dominant fungal phyla in the soils of each treatment were Ascomycota, Mortierellomycota, Basidiomycota, Chytridiomycota, Glomeromycota, Rozellomycota, and Cysticercales, and the dominant genera were Gibberella, Chaetomium, Sarocladium, Stachybotrys, and Fusarium. Compared to that under freshwater irrigation, saline water irrigation significantly increased the relative abundance of Basidiomycota and Chytridiomycota and significantly decreased the relative abundance of Ascomycota and Rozellomycota. The application of biochar under saline irrigation significantly increased the relative abundance of Ascomycota and Sarocladium but significantly decreased the relative abundance of Basidiomycota, Chaetomium, and Fusarium. LEfSe analysis showed that under the condition of no biochar application, saline irrigation reduced the number of potential biomarkers of fungal communities, whereas the application of biochar under the condition of saline irrigation increased the number of potential biomarkers of fungal communities. These results indicated that the application of biochar can improve the saline soil environment and fungal community structure and provide a theoretical basis for reasonable brackish water irrigation and soil fertilization in arid areas.

Machine learning based prediction model for the pile bearing capacity of saline soils in cold regions

The difficulty in determining the bearing capacity of pile foundations in saline soil environments in cold regions can pose a challenge when developing a bearing capacity prediction model. To address this, the study uses data from the construction of the De Xiang Expressway project in Qinghai Province, China, and considers pile length, pile diameter, corrosion depth, and spalling thickness as influential parameters. We combine Python with ABAQUS to build a finite element model of a single pile in a salt marsh environment with random parameters and develop a database for machine learning. We use the kernel ridge regression (KRR) and multilayer perceptron (MLP) algorithms to establish load-bearing capacity prediction models for vertical and horizontal loads, respectively. The SHAP (SHapley Additive exPlanations) method is employed to perform explanatory analysis on the prediction models, providing insight into influential parameter effects on prediction accuracy. The results demonstrate that the database established through the random parameter finite element method is suitable for machine learning. While the KRR model exhibits good performance in predicting vertical load-bearing capacity, the MLP model performs well in predicting horizontal load-bearing capacity. Moreover, the SHAP method effectively explains the importance of influential parameters on the prediction results and enhances the reliability of the prediction models. The vertical bearing capacity of a saline soil pile foundation is more affected by the depth of salt erosion than the thickness of spalling, while the horizontal bearing capacity is more affected by the thickness of spalling than the depth of salt erosion.

Corrosion Deterioration of Reinforced Concrete in a Saline Soil Environment

Corrosion Deterioration of Reinforced Concrete in a Saline Soil Environment

Study on ecological stoichiometry homeostasis characteristics of different halophytes in the Yellow River Delta

AbstractEcological stoichiometric homeostasis represents the physiological and biochemical adaptations of organisms to variations in environmental conditions and plays a pivotal role in maintaining ecosystem stability. However, existing literature predominantly concentrates on the changes in plant homeostasis under different external environments. There is a paucity of comparative analyses focusing on the stoichiometric homeostasis attributes among different types of halophytes, particularly using these halophytes as a primary investigative lens. In this study, by analyzing the differences in organ and soil ecological stoichiometry as well as salt accumulation characteristics of three halophytes (Phragmites communis, Suaeda salsa, and Tamarix chinensis) in the Yellow River Delta, we revealed the salt ion enrichment capacity and stoichiometric homeostasis characteristics of the three halophytes and clarified the adaptive capacity of the three halophytes in saline soil environments. Our results indicated that S. salsa accumulated more Na+ and Mg2+, while P. communis maintained a low salt content in its surrounding soil. The soil C:N ratios of P. communis and S. salsa negatively correlated with most ions, while T. chinensis displayed a positive correlation with ions. S. salsa demonstrated the highest ion enrichment but the least homeostasis, whereas T. chinensis showed superior homeostasis. We hypothesize that T. chinensis might have experienced a faster growth rate during the study period, and P. communis' topsoil appears to be more conducive for plant growth. The different salt tolerance strategies of these plants influenced homeostasis, with S. salsa demonstrating greater adaptability to soil modifications and higher potential in saline land management. These insights enhance our understanding of the physiological and ecological adaptations of halophytes and their contribution to improving the quality of saline soils in the Yellow River Delta.

Failure Mechanism and Control Measures of Cu-CuSO4 Electrode in Saline Soil Environment

Saline soil environment is widely distributed in western China, especially in Qaidam Basin. High salinity soil in Qaidam Basin has higher corrosion risk to metal pipelines. The Cu-CuSO4 electrode is used as the long-term reference electrode in the cathodic protection system of oil and gas pipeline. In saline soil environment, the Cu-CuSO4 reference electrode generally has a problem of excessive drift, which seriously affects the normal operation of cathodic protection system. The failure mechanism of the Cu-CuSO4 reference electrode in saline soil environment was demonstrated: soil ion pollution and drain drying caused potential drift. In view of the main factors affecting Cu-CuSO4 reference electrode drift in saline soil environment, measures such as adding packing material and setting up maintenance device were developed, and the field application effect was good. It provides a technical idea for prolonging the life of cathodic protection system in saline soil environment.

Fragility analysis of an ultra high voltage transmission tower in saline soil subjected to wind loads

The wind resistance of transmission towers is not only affected by wind load, but also by service environment. This study uses the world’s second Ultra High Voltage Direct Current transmission project – Xinjiang ±800 kV Tianzhong Line UHV DC transmission project – to develop a fragility analysis method for transmission towers in saline soil under wind loads to investigate the change of wind loads fragility of transmission towers in long-term service in the saline soil environment. It develops a tower-line-foundation (3 T-2L-F) system model considering soil-structure interaction. In addition, this research addresses the durability damage of the transmission tower using field investigation data and material degradation models and analyzes the influence of various durability damage components on the natural vibration mode of the basic of 3 T-2L-F model. Finally, it builds the structure-wind samples utilizing a Latin hypercube sampling method and explores the time histories analysis, the pushover analyses, and the time-varying fragility analyses considering the uncertainty of materials and wind loads. The findings indicate that the 3 T-2L-F model accurately simulates the actual situation of the transmission tower. The fragility of a transmission tower subjected to wind loads is proportional to the degree of material damage and the strength of wind loads.

Stress corrosion cracking behavior of X80 pipeline steel under alternating current, Desulfovibrio desulfurican and cathodic protection potential

The stress corrosion cracking (SCC) behavior of X80 pipeline steel under Desulfovibrio desulfurican (D. desulfurican), alternating current (AC) and cathodic protection (CP) was studied by the constant load tests and slow strain rate tensile (SSRT) test. The results showed that both AC interference and relatively negative CP potential aggravated pitting corrosion and enhanced the SCC susceptibility under the constant load. In the saline soil environment containing D. desulfurican, the AC greatly contributed to the cracking tendency of X80 pipeline steel and resulted in the safe CP range that was too narrow for practical engineering application, thus requiring appropriate discharge methods.

Effect of hoop restraint on the degradation behavior of cement paste exposed to sodium sulfate solution

Concrete filled steel tube (CFST) is an effective method to alleviate sulfate attack in saline soil environments. In this study, the effect of hoop restraint on the degradation behavior due to sulfate attack in ordinary Portland cement (OPC) paste and sulfate-resistance Portland cement (SRPC) pastes is studied. The cracking behavior and mass variation are determined to investigate deterioration process of the pastes. EPMA-WDS, nanoindentation and SEM-EDS are performed to analyse the deterioration mechanism of the cement paste under hoop restraint condition. As the results shown: The deterioration behaviors of cement pastes is strongly affected by hoop restraint. Specifically, the hoop restraint inhibited crack formation of the specimens and formation of sulfate products. The average effective sulfate diffusion coefficient is reduced by 30.26% and 5.81% for OPC and SRPC paste during 365 days of exposure, respectively, compared with the reference group. Moreover, the mechanism of deterioration of cement paste under hoop restraint condition is proposed based on change in chemical component of C–S–H phase. The hoop restraint from steel tube can effectively inhibit the sulfate attack on cement composite with important engineering significance.

Evaluation of some Barley Genotypes under Saline Soil Conditions

This study examined ten barley genotypes under both normal and saline soil environments at Sakha Agricultural Research Station, during two growing seasons 2019/2020 and 2020/2021. A randomized complete block design with four replications was used for each experiment. Some traits were recorded i.e. days to maturity, plant height (cm), spike length (cm), number of spikes m-2, number of grains spike-1, grain yield (t ha-1), biological yield (t ha-1), chlorophyll, K, Na content and K/ Na ratio. Analysis of variance for years, locations, genotypes and interaction were significant and highly significant for all studied traits. Results revealed that, the evaluated genotypes revealed a wide variation in salinity sensitivity. Line-1 and Line-6 gave the most desirable values of yield and related traits as well as physiological parameters under studied environments in both seasons, so we can recommend those genotypes under salinity conditions.

Soil Fungal Community Structure and Its Effect on CO2 Emissions in the Yellow River Delta

Soil salinization is one of the most compelling environmental problems on a global scale. Fungi play a crucial role in promoting plant growth, enhancing salt tolerance, and inducing disease resistance. Moreover, microorganisms decompose organic matter to release carbon dioxide, and soil fungi also use plant carbon as a nutrient and participate in the soil carbon cycle. Therefore, we used high-throughput sequencing technology to explore the characteristics of the structures of soil fungal communities under different salinity gradients and whether the fungal communities influence CO2 emissions in the Yellow River Delta; we then combined this with molecular ecological networks to reveal the mechanisms by which fungi adapt to salt stress. In the Yellow River Delta, a total of 192 fungal genera belonging to eight phyla were identified, with Ascomycota dominating the fungal community. Soil salinity was the dominant factor affecting the number of OTUs, Chao1 index, and ACE index of the fungal communities, with correlation coefficients of -0.66, 0.61, and -0.60, respectively (p < 0.05). Moreover, the fungal richness indices (Chao1 and ACE) and OTUs increased with the increase in soil salinity. Chaetomium, Fusarium, Mortierella, Alternaria, and Malassezia were the dominant fungal groups, leading to the differences in the structures of fungal communities under different salinity gradients. Electrical conductivity, temperature, available phosphorus, available nitrogen, total nitrogen, and clay had a significant impact on the fungal community structure (p < 0.05). Electrical conductivity had the greatest influence and was the dominant factor that led to the difference in the distribution patterns of fungal communities under different salinity gradients (p < 0.05). The node quantity, edge quantity, and modularity coefficients of the networks increased with the salinity gradient. The Ascomycota occupied an important position in the saline soil environment and played a key role in maintaining the stability of the fungal community. Soil salinity decreases soil fungal diversity (estimate: -0.58, p < 0.05), and soil environmental factors also affect CO2 emissions by influencing fungal communities. These results highlight soil salinity as a key environmental factor influencing fungal communities. Furthermore, the significant role of fungi in influencing CO2 cycling in the Yellow River Delta, especially in the environmental context of salinization, should be further investigated in the future.

Corrosion resistance of magnesium phosphate cement under long-term immersion in different solutions

Magnesium phosphate cement (MPC) is widely utilised in engineering. However, it may be subject to corrosion in the Western Chinese saline soil environment. This study analysed the factors of magnesium phosphorus ratio, borax content, water binder ratio and fly ash content. Mix proportions of MPC were devised through orthogonal testing. The corrosion performance of MPC specimens in water, 5% Na2SO4 solution, 5% NaCl solution and saline soil solution were analysed in terms of mass loss and the strength anti-corrosion coefficient. The corrosion mechanisms of MPC in different solutions were analysed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Thermogravimetric and differential scanning calorimetry (TG-DSC) and Scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). There were no obvious changes in MPC appearance or morphology after soaking in different solutions for 180 days. The mass loss was < 5% and the strength loss was < 25%, indicating that MPC has good resistance to saline soil and other saline solutions. The strength anti-corrosion coefficients of MPC soaked in various solutions for 180 days were > 0.75, and the influences on strength can be ranked as follows: 5% Na2SO4 solution > saline soil solution > water > 5% NaCl solution. On the basis of TG-DSC, FTIR and XRD analyses, when MPC was soaked in different solutions for 180 d, the contents of the hydration product MgKPO4·6H2O (MKP) were ranked as water > 5% NaCl solution > saline soil solution > 5% Na2SO4 solution. SEM-EDS analysis shows that MKP was corroded to varying degrees after the MPC was soaked in different solutions, with the 5% Na2SO4 solution causing the greatest corrosion.

Hysteretic model of reinforced concrete bridge piers based on earthquake damage and corrosion from saline soil

A hysteretic model of reinforced concrete (RC) bridge piers in saline soil environment, incorporating corrosion-induced overall structural degradation, is obtained based on earthquake damage by applying damage parameter. A damage analysis of the observed 13 RC bridge piers tested under cyclic loading including cracks evolution, residual deformation, relative unloading degradation, cyclic unloading stiffness degradation and strength deterioration is presented. A quantification approach for seismic damage considers the sources of deterioration: i.e., number of loading cycles and controlled displacements and incorporates a deterioration parameter aiming to control the deterioration modes. The skeleton model consists of three segments and is determined by simplifying the experimental skeleton curve. Yield strength reduction and sectional loss of reinforcement are computed to characterize the corrosion-induced degradation. It is determined that the equivalent skeleton model could match the experimental results. The applicability as well as accuracy of proposed model in simulating the hysteretic behaviours are calibrated by comparing the model with the experimental curves. The model is capable to approximate the complete hysteretic response.

Synergistic combination of arbuscular mycorrhizal fungi and plant growth-promoting rhizobacteria modulates morpho-physiological characteristics and soil structure in Nitraria tangutorum bobr. Under saline soil conditions

Nitraria tangutorum Bobr., a typical xero-halophyte, can be used for vegetation restoration and reconstruction in arid and semiarid regions affected by salinity. However, global climate change and unreasonable human activity have exacerbated salinization in arid and semi-arid regions, which in turn has led to the growth inhibition of halophytes, including N. tangutorum. Arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) have the potential to improve the salt tolerance of plants and their adaptation to saline soil environments. In this study, the effects of single and combined inoculations of AMF (Glomus mosseae) and PGPR (Bacillus amyloliquefaciens FZB42) on N. tangutorum were evaluated in severe saline soil conditions. The results indicate that AMF and PGPR alone may not adapt well to the real soil environment, and cannot ensure the effect of either growth promotion or salt-tolerance induction on N. tangutorum seedlings. However, the combination of AMF and PGPR significantly promoted mycorrhizal colonization, increased biomass accumulation, improved morphological development, enhanced photosynthetic performance, stomatal adjustment ability, and the exchange of water and gas. Co-inoculation also significantly counteracted the adverse effect of salinity on the soil structure of N. tangutorum seedlings. It is concluded that the effectiveness of microbial inoculation on the salt tolerance of N. tangutorum seedlings depends on the functional compatibility between plants and microorganisms as well as the specific combinations of AMF and PGPR.