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

Abstract

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

In this study, we conducted a barrel experiment in which soil was mixed with NaCl and Na₂CO₃ to achieve a salinity level of 8 g·kg⁻¹, and then placed in barrels with a diameter of 50 cm and a height of 60 cm, then the barrels were buried in cotton fields. And soil conditioner GS was applied to improve the salt-stressed and alkali-stressed soil. This study investigated the effect of soil conditioner GS on soil microbial life history strategies under simulated saline and alkaline stress during cotton flowering in saline soils. The study explore the effects of soil amendment GS on soil microbial life history strategies under simulated saline and alkali stresses during cotton flowering stage for saline soil.

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.