Responses of rhizosphere microbial communities and resource competition to soil amendment in saline and alkaline soils

Background and aims Soil amendments have been widely applied in the remediation of saline soil and the improvement of crops resistance to external stresses. However, the responses of soil microbial community composition, structure, function, and resource competition strategy to soil amendment in saline and alkaline soil remain unclear. Methods A barrel experiment was performed in a cotton field to explore the effects of soil amendment on soil microbial life history strategies under simulated saline and alkali stresses during cotton flowering stage. Results The results showed that saline and alkali stresses disrupted soil microbial succession and altered rhizosphere soil micro-environment. However, after the application of amendment in saline soil, the abundance of dominant bacteria (Subgroup_17) and fungi (Mortierella, Chaetomium), soil metabolic functions (biosynthesis of amino acids and fatty acid), soil K⁺ content and Si/N ratio significantly increased, while soil Na⁺ content and electrical conductivity (EC) significantly reduced. After the application of amendment in alkaline soil, the abundance of dominant soil bacteria (Aeromicronium, Rokubacteriales, RB41) and fungi (Mycosphaeralla, Aspergillus), phenylalanine metabolise and fatty acid biosynthesis pathways soil K⁺/Na⁺ ratio, organic carbon content, total nitrogen, and Si/N ratio significantly increased, while soil Na⁺ content, pH, and Si/C ratio significantly decreased. Conclusions Application of soil amendment could significantly increased soil nutrient content,the formation of different life cycle strategies of soil microorganisms, so as to alleviate the saline stress and alkali stress. This study provides reference for alleviating the saline and alkaline stresses to cotton by influencing key soil microorganisms using soil amendment.