The agricultural productivity of farmland in Northeast China’s Liaohe Plain is restricted by the salinity and sodicity of the soils, which have additionally low organic matter content. In order to improve saline–sodic soils, organic amendments are frequently applied. Our objective was to clarify how different organic amendments affect the diversity and composition of soil microbes, as well as how these factors are related to crop yield. In 2020–2021, we conducted an experiment with different organic amendments. The treatments included the application of crop residue incorporation (SR), lignite humic acid (LHA; 6 ton/ha), or cow manure (FM; 30 ton/ha), and a control (CK). The results show that, compared with CK, the content of SOM in soil treated with organic amendments increased by 5.3–7.4 g/kg; the available potassium (AK) of the LHA treatment was significantly higher than that of the FM and SR treatments by 32.17 and 42.79 mg/kg, respectively; and the available phosphorus (AP) of the LHA treatment was significantly higher than that of the SR treatment by 7.19 mg/kg. The pH and EC_1:5 values of the LHA treatment were significantly lower than those of CK by 1.36 units and 0.2 mS/cm, respectively. The application of organic amendments and changes in environmental conditions also significantly affected community structure and increased soil microbial richness and diversity. SR treatment increased the abundance of Acidobacteria. Further FAPROTAX (Functional Annotation of Prokaryotic Taxa) analysis showed that organic amendments can increase the abundance of microbes involved in the carbon and nitrogen cycle processes, such as aerobic_ammonia_oxidation, aerobic_chemoheterotrophy, nitrification, etc., which increases the kernel number per row and increases crop yield. LHA can increase the microbial abundance of the nitrogen cycle and reduce soil carbon mineralization, while also increasing soil nutrients and crop yield. This study provides a comprehensive understanding of the application of organic amendments in saline–sodic cultivated land.

Introduction: In the soda-saline grasslands of the Songnen Plain, Jilin Province, China, the prohibition of grazing has led to significant changes in plant communities and soil properties. However, the intricate interplay between soil physical and chemical attributes, the soil microbial community, and their combined influence on soil humus composition remains poorly understood.Methods: Our study aimed to evaluate the impact of natural vegetation restoration on soil properties, microbial community diversity, and composition in the soda-saline soil region of the Songnen Plain. We conducted assessments of soil physical and chemical properties, analyzed community diversity, and composition at a soil depth range of 0–20 cm. The study covered soils with dominant soda-saline vegetation species, including Suaeda glauca Bunge, Puccinellia chinampoensis Ohwi, Chloris virgata Swarta, Phragmites australis (Clay.), Leymus chinensis (Trin.), and Tzvelev. We compared these vegetated soils to bare land devoid of any plants.Results: We found that soil organic content (SOC) in vegetation restoration areas was higher than in bare land, with SOC content varying between 3.64 and 11.15 g/kg in different vegetated areas. Notably, soil pH emerged as a pivotal factor, explaining 11.4% and 12.2% of the variance in soil bacteria and fungi, respectively. There were correlations between SOC content and the relative abundance of specific microbial groups, with Acidobacteria and Mortierella showing a positive correlation, while Actinobacteria, Gemmatimonadetes, and Ascomycota exhibited significant negative correlations with SOC.Discussion: The disparities in SOC composition and content among the soda-saline vegetation types were primarily attributed to variations in pH. Consequently, reducing soil pH is identified as a critical step in the process of vegetation restoration in soda-saline land. Prohibiting grazing has the potential to increase soda-saline SOC content and enhance microbial diversity, with Leymus chinensis and Phragmites australis showing particularly promising results in terms of higher SOC carbon content and microbial diversity.

Background: Saline-sodic soils are widely distributed in arid and semi-arid regions around the world. High levels of salt and sodium inhibit the growth and development of crops. However, there has been limited reports on both osmotic potential in soil solutions (OP_ss) and characteristics of Na⁺and K⁺absorption in rice in saline-sodic soils under various amendments application.Methods: A field experiment was conducted between 2009 and 2017 to analyze the influence of amendments addition to saline-sodic soils on rice growth and yield. Rice was grown in the soil with no amendment (CK), with desulfurization gypsum (DG), with sandy soil (SS), with farmyard manure (FM) and with the mixture of above amendments (M). The osmotic potential in soil solution, selective absorption of K⁺over Na⁺(SA), selective transport of K⁺over Na⁺(ST), the distribution of K⁺and Na⁺and yield components in rice plants were investigated.Results: The results indicated that amendments application have positive effects on rice yield. The M treatment was the best among the tested amendments with the highest rice grain yield. M treatment increased the OP_ssvalues significantly to relieve the inhibition of the water uptake by plants. Additionally, the M treatment significantly enhanced K⁺concentration and impeded Na⁺accumulation in shoots. SA values were reduced while ST values were increased for all amendments. In conclusion, a mixture of desulfurization gypsum, sandy soil and farmyard manure was the best treatment for the improvement of rice growth and yield in the Songnen Plain, northeast China.

Four typical halophytic communities found in saline-sodic soil, including Phragmites australis, Suaeda glauca, Leymus chinensis, and Puccinellia parl, were investigated in this study. A comparison was made among the electrical conductivity (EC) value, pH value, soil organic carbon (SOC), and soil enzyme activity across various soil depths. The findings of this study indicate that the EC and pH levels of the soil at the 0–40 cm depth vary among the four communities, with Suaeda glauca having the highest values, followed by Puccinellia parl, Phragmites australis, and Leymus chinensis. The highest value of SOC among the four communities was observed in the Leymus chinensis community (0.85–0.94 g/kg), followed by the Phragmites australis community (0.50–0.77 g/kg), and the lowest levels were observed in the Puccinellia parl community (0.37–0.78 g/kg). As the soil depth increases, there is a decline in the amount of SOC. With an increase in soil depth, the content of SOC in the soil decreased, and the content of total nitrogen (TN) and the activity of six enzymes in the soil of each community increased. Furthermore, at the soil layer of 0–20 cm, the TN content in the soils was negatively correlated with pH and EC (p < 0.01), and so was the total phosphorus (TP). Additionally, the TP content is considerably positively connected with alkaline phosphatase (ALP) activity, whereas the TN content is significantly positively correlated with Soil Urease (S-UE) activity. Within the soil depth of 20–40 cm, the levels of TN, TP, and SOC exhibit a negative association with pH and EC. However, this link is weaker compared to that observed in the surface soil. A strong inverse correlation (p < 0.05) exists between the TP concentration and the ALP activity. The objective of this study was to investigate the use of halophytes in various saline-sodic soils for diverse avenues of restoration, and to establish a database on the role and efficacy of plant roots in enhancing saline-sodic soil.